Recent Comments

Prev  2581  2582  2583  2584  2585  2586  2587  2588  2589  2590  2591  2592  2593  2594  2595  2596  Next

Comments 129401 to 129450:

129401. Mizimi at 06:37 AM on 11 November 2008
        Water vapor is the most powerful greenhouse gas
        You seem to be arguing that AWV has virtually no effect but as soon as CO2 induces increase in WV by warming the atmosphere a fraction of a degree there is a WV 'positive feedback' which is admitted...even when the amount is unquantified and probably quite small itself? And that somehow, despite adding AWV, the atmospheric total of WV remains more or less constant because of precipitation; yet we know it doesn't. It fluctuates all the time. "As the temperature of the atmosphere rises, more water is evaporated from ground storage (rivers, oceans, reservoirs, soil). Because the air is warmer, the relative humidity can be higher (in essence, the air is able to 'hold' more water when its warmer), leading to more water vapor in the atmosphere. As a greenhouse gas, the higher concentration of water vapor is then able to absorb more thermal IR energy radiated from the Earth, thus further warming the atmosphere. The warmer atmosphere can then hold more water vapor and so on and so on. This is referred to as a 'positive feedback loop'. #However, huge scientific uncertainty exists in defining the extent and importance of this feedback loop.# # As water vapor increases in the atmosphere, more of it will eventually also condense into clouds, which are more able to reflect incoming solar radiation (thus allowing less energy to reach the Earth's surface and heat it up).# The future monitoring of atmospheric processes involving water vapor will be critical to fully understand the feedbacks in the climate system leading to global climate change. #As yet, though the basics of the hydrological cycle are fairly well understood, we have very little comprehension of the complexity of the feedback loops.# Also, while we have good atmospheric measurements of other key greenhouse gases such as carbon dioxide and methane, #we have poor measurements of global water vapor, so it is not certain by how much atmospheric concentrations have risen in recent decades or centuries,# though satellite measurements, combined with balloon data and some in-situ ground measurements indicate generally positive trends in global water vapor. http://lwf.ncdc.noaa.gov/oa/climate/gases.html
129402. Quietman at 06:34 AM on 11 November 2008
        It's the sun
        chris That is correct. SO by removing the catalytic converter we would reduce CO2 output and lower the 12C/13C ratio.
129403. Patrick 027 at 06:22 AM on 11 November 2008
        Arctic sea ice melt - natural or man-made?
        Actually, if the diabatic residual meridional circulation exists, the coriolis effect acts on that to accelerate zonal winds, opposing the effect of southward eddy IPV flux. The coriolis effect acts on the Ferrel cell motion to oppose the effect of momentum flux convergence and to reduce the vertical wind shear, which will also bring the wind toward geostrophic balance with the reduced thermal gradient due to eddy heat fluxes. ----- Another way to look at the horizontal and vertical scale relationships: As illustrated above (independently of the IPV concept), following the motion of the air at one level, increasing cyclonic vorticity advection with height (or decreasing anticyclonic vorticity advection with height) creates an imbalance that drives either divergence above or convergence below or both; and *1. one (convergence below or divergence above) will drive the other by changing the pressure at all levels in an atmospheric column (assuming hydrostatic balance is at least approximately maintained). This produces by mass continuity (while remaining close to hydrostratic balance) upward vertical motion (in x,y,p coordinates; upward vertical motion is negative Dp/Dt). *2. The upward vertical motion causes adiabatic cooling as isentropes are displaced vertically (diabatic heating such as by latent heating will reduce that). *3. This change in temperature changes the vertical pressure gradient. *3 only happens if the air is stable and is proportional to that stability; with constant potential temperature with height, the temperature at any given pressure level remains the same. *4. The horizontal pressure gradient changes associated with the adiabatic cooling, modulated by stability, intensifies the relative low pressure above and reduces it below, thus reducing the convergence below and increasing it above, as the divergence pattern acts to vertically contain the voriticity pattern, against the tendency for vorticity (and associated curvature of the horizontal pressure field) changes to spread vertically by *1. HOWEVER, in order for *2, via *3, to cause *4, there has to be a curvature in the induced temperature anomaly field - the Laplacian of the temperature must be nonzero - in other words, If the vertical variation in vorticity advection were constant over some horizontal region, and the stability is also constant as is the absolute vorticity at a given vertical level, then the adiabatic cooling is constant and thus has no horizontal temperature gradient associated with it, and no horizontal pressure variation and no geostrophic vertical wind shear. Aside from variations in AV and stability, it is the horizontal variation in the vertical variation of vorticity advection that allows the adiabatic warming or cooling to limit the vertical extent of induced vorticity. Hence, larger vertical extents are supported by larger horizontal scales. The vertical variation in vorticity advection is 'differential vorticity advection'. When does differential vorticity advection (DVA) happen? 1. vertical wind shear across a vertically-constant vorticity gradient, including the planetary vorticity gradient. 2. constant wind across a vertically-varying vorticity gradient. 3. some combination of wind shear and variation of vorticity gradient with height. But notice that if 2 is the case, this only moves an entire atmospheric column. Thus, there is no level to be found at which, following the motion of the air, there would actually appear to be vorticity advection above or below. 2 by itself does not cause any divergence or vertical motion. However, the vertical variation in the relative vorticity gradient would, assuming near geostrophy, be related to temperature variations. Horizontal variations in temperature advection will drive divergence and vertical motions. Specifically, cyclonic RV increasing with height implies a cold temperature anomaly that decreases away horizontally (positive Laplacian of temperature) If the wind does not vary horizontally, the temperature pattern is advected in whole and this by itself does not cause any imbalance. If there is varyation in the wind over horizontal distances, then the temperature advection pattern can produce changes in the horizontal temperature gradient following the motion. Specifically it is the convergence of the change in temperature gradient FOLLOWING the motion that drives upward motion. It turns out that because of the relationship between geostrophic vertical wind shear ('the thermal wind') and the horizontal temperature gradient, the effect of differential relative geostrophic vorticity advection by geostrophic winds, FOLLOWING the geostrophic motion, is the same as the effect of the changing temperature gradient, FOLLOWING the geostrophic motion, so that - (?)the combined effect on vertical motion and convergence and divergence is twice the effect of either by itself (?) - I think; - this relates to something called the Q vector.
129404. John Cross at 02:32 AM on 11 November 2008
        A Great Science Fiction Writer Passes - Goodbye Dr. Crichton
        Quietman: I also liked the 13th Warrior - although it got a little over the top at the end. I did not like Prey at all. It is possible that since I am involved in a field close to fluid mechanics I am more critical of some of the fluid parts than others would be. Anyway, I did not find it his best work. I have not read State of Fear - but I have read enough excerpts to get an idea. I am sure that if one keeps in mind that it clearly is a work of fiction then it would appeal to some people. Regards, John
129405. chris at 23:34 PM on 10 November 2008
        It's the sun
        Chemical catalysis has zero effect on 13C. There is a fundamental difference between chemistry (catalysed or uncatalysed bond making and breaking) and nuclear physics (extremely high energy transformation of the structure of atomic nuclei). So fossil-fuels have highly depeleted 13C relative to the natural abundance of 13C, since plants have a significant "preference" for the uptake of 12C CO2 over 13C CO2 when they draw CO2 out of the atmosphere. As the plants are "fossilised" into coal, oil and natural gas, shales, peat and so on, they retain this highly depleted ratio of 13C/12C. 13C and 12C cannot interconvert by chemical processes. When the fossil fuel is returned to the atmosphere by burning the 13C-depleted CO2 is at long long last returned to the atmosphere, and the 13C/12C ratio of atmospheric CO2 drops. This doesn't happen to any significant extent with CO2 released by volcanoes, since (first) volcanoes and tectonic activity in general doesn't release much CO2 as we can observe by inspecting the atmospheric CO2 records at high resolution for 1000's of years, and at low resolution for millions of years. Sedimented carbonates, and even the shells of marine organisms give rise to very, very small differences in the 13C/12C ratio, and these relate more to the physicochemical "fractionation" as a function of temperature. Since 13C is essentially unaffected by any processes outwith particle accelerators, nuclear reactors and so on, in which nuclear transformations can take place, 13C is effectively inviolate in the Earth [***]. So as we burn fossil fuels a 12C carbon remains as a 12C isotope and likewise a 13C carbon atom. This occurs if the CO2 is produced by direct oxidation of carbon or hydrocarbon, or if a small amount of the hydrocarbon is left partially unoxidised or in the form of carbon monoxide, and is subsequently oxidised "to completion" within a catalytic converter. The answer to your specific question of post #207 is yes..you would measure the same 13C/12C raio in airborned hydrocarbon and carbon monoxide, whether or not these were vapourized directly into the air or fully oxidised to carbon dioxide within a catalytic converter. [***]The unstable carbon isotope 14C is produced in very small amounts in the upper atmosphere by the action of gamma rays, at much lower energies than required to produce the stable isotope 13C, and this provides the basis of using 14C decay as an "atomic clock" in radiocarbon dating. Note that the atmospheric 14C content can be used to distinguish fossil-fuel-derived carbon from deforestation-derived carbon, since the 1/2 life of 14C radioactive decay (a bit under 6000 years) is long relative to the life of trees (except for the most ancient of these like the bristlecone pines in the west of the USA!), but very short relative to the time that fossil fuels have lain undistrubed underground. This is somewhat complicated by the fact that just the short period of nuclear device testing in the 1940's through the 1960's has produced quite a significant spike in the atmospheric 14C content, and needs to be corrected for...
129406. Patrick 027 at 16:23 PM on 10 November 2008
        Arctic sea ice melt - natural or man-made?
        Potential point of confusion: When I described the effect of vertical variations in vorticity advection, I mentioned that an 'injection' of cyclonic vorticity concentrated at some level would lead to divergence at that level (and then leading to convergence at other levels, etc.). Convergence would occur if vorticity is removed from some level (causing divergence at other levels, etc.). Thus, a vorticity maximum that is being transported relative to air at other levels (rather than along with the whole column, in which case everything stays balanceds and there is no convergence or divergence except for changes in planetary vorticity or topography, etc.), while inducing features above and below that would follow it, should also be slowed down relative to the basic state wind that carries it along, by the process of inducing those motions above and below. But how can that happen with an IPV anomaly, since IPV is conserved following the motion in adiabatic processes? Is it necessary to include the Rossby-wave propagation to resolve this? ---- PS from Cushman-Roisin, p.87: The group velocity of barotropic Rossby waves (just due to the beta effect, gradient of AV is to the north): For longer wavelengths, the group velocity is to the west; for shorter wavelengths, to the east; the divide between the two occurs at the maximum frequency for a given meridional wavenumber; at which point the group velocity is due north or south; for waves with phase propagation to the the northwest or southwest, the meridional component of the group velocity is to the south or north, respectively (in the opposite direction of phase propagation). My earlier 'work' (comment 296) on Rossby wave frequency suggested that the frequency can be arbitrarily large; but this is not actually true; there is an upper limit. I'm not 100% sure but it seems as if the Cushman-Roisin derivation, pp.83-87, includes the effects of divergence; this may be what places an upper limit on frequency, then. The limit of westward phase speed at arbitrarily large wavelengths is equal to the product of beta and the square of the external Rossy radius of deformation; the highest frequency allowed is the product of beta and the external Rossby radius of deformation divided by 4*pi. (In these derivations it was assumed there was no RV contribution to the vorticity gradient.) Interestingly, the lowest frequency allowed for inertio-gravity waves is f/(2pi), the frequency of inertial oscillation (when RV = 0); and that limit is achieved at infinite wavelength (Cushman-Roisin, p.83). According to Cushman-Roisin, it was assumed in the derivation of Rossby wave formulas that the expression for frequency would be less than the minimum frequency of inertio-gravity waves. The highest frequency Rossby waves actually are not quite the longest wavelengths in this formulation; they occur with meridional wavenumber = 0, so that the phase lines are oriented north-south, the wave phase propagation is due west, the zonal wavenumber is 1/(external Rossby radius of deformation), so the wavelength is equal to 2pi*(external Rossby radius of deformation). ---- EP flux and eddy IPV flux: Specifically (Holton pp.323,327): The EP flux is a vector in a vertical meridional plane (at least in this application), where the northward component is proportional to -u'v' (the southward eddy zonal momentum flux) and the upward component is proportional to v'T' (the northward eddy temperature flux). Thus v'T' decreasing with height and u'v' increasing northward (implying eddy zonal momentum flux DIVERGENCE which would tend to slow the average westerly winds) would tend to lead to EP flux CONVERGENCE (I say 'tend to' because those quantities have to be multiplied by some coefficients to actually get the EP flux, and some of those can vary). The EP flux convergence corresponds and is proportional to a southward eddy flux of IPV (Holton p.327) which makes sense since increasing RV to the south and decreasing RV to the north implies an average slowing of westerly winds and a divergence of zonal momentum flux, and decreasing v'T' with height implies an average decrease in static stability to the north and the opposite to the south. The actual tendency of the eddy fluxs and EP flux in mid-to-high latitudes (Holton p. 324, pp.319-325) is: 1. generally for poleward temperature flux v'T' between the subtropics and polar latitudes, which increases with height from the surface to some low level in the troposphere, but after that a general decrease with height within the troposphere, a minimum near the tropopause (at least in winter, or more clear in winter** in Fig 10.3), and increasing again somewhat into the stratosphere in winter (**Fig 10.3 - I'm assuming some similarity between southern winter and northern winter, and for the two summers, but of course there will be differences too). 2. generally poleward zonal momentum flux over the subtropics and some equatorward zonal momentum flux over subpolar latitudes, so that there is a zonal momentum convergence between subtropics and subpolar latitudes, and this is generally a maximum near the tropopause (where there is a maximum in jet stream velocity). Thus in the midlatitudes there tends to be eddy momentum flux u'v' convergence increasing with height within the troposphere (and decreasing above that at least to some point), and poleward eddy heat flux that generally decreases upward within the troposphere except near the surface (the lower near surface values are probably due to frictional slowing of the winds, I think). The contributions to EP flux divergence: the momentum fluxes would lead to EP flux divergence especially near the tropopause; generally the effect of thermal fluxes dominates, however, so in most of the troposphere the EP flux is convergent, except for some significant divergence next to the surface (also due to thermal fluxes). It approaches zero divergence around the tropopause level. The effect of that is to slow the average zonal momemtum, except just above the surface where it could accelerate the average zonal momentum. The coriolis effect would act on this perturbation to acceleration the motion poleward in the mid troposphere and equatorward just near the surface. The overturning that this describes is a diabatic circulation (rising air is being heated by latent heating and/or radiation, sinking air is being cooled by radiation) and is in a way an extension of the Hadley cell. But wait! Where did the midlatitude Ferrel cell go? Actually, the EP flux 'includes' the adiabatic portion of the Ferrel cell, which dominates over the 'residual meridional circulation' (p.323) in the Eulerian zonal mean. The adiabatic portion is rising poleward and sinking over the subtropics. In the full Eulerian mean, the vertical distribution of zonal momentum convergence perturbs the average motion, the eddy heat and the coriolis effect acts on that to produce meridional circulation in the same direction as the ferrel cell, and the poleward eddy heat flux causes a similar overturning. (Having trouble with that? So did I!)
129407. Quietman at 15:59 PM on 10 November 2008
        It's the sun
        Or put another way, would you measure the same C13/C12 ratio in airborne HC and CO?
129408. Quietman at 15:57 PM on 10 November 2008
        It's the sun
        ps A byproduct is SO2.
129409. Quietman at 15:54 PM on 10 November 2008
        It's the sun
        chris We use a series of catalysts inside every catalytic converter to transform HC, CO and NOx into H2O and CO2, starting in CA in 1974 and nationwide after 1975 depending on engine size. Almost all passenger vehicles were equipped with cats by 1978. Then there are the industrial stacks. The converters for stacks are also aimed at producing CO2 and H20. This is mandated by the EPA. So what effect does the cat have on C13?
129410. Quietman at 15:32 PM on 10 November 2008
        Volcanoes emit more CO2 than humans
        Mystery Wave Strikes Maine Harbor By Robert Roy Britt, LiveScience Managing Editor, 04 November 2008: "A series of large, unexpected tsunami-like waves as high as 12 feet struck Maine's Boothbay Harbor on Oct. 28, and there's still no explanation for what caused them."
129411. Patrick 027 at 12:20 PM on 10 November 2008
        Arctic sea ice melt - natural or man-made?
        According to Bluestein (p.193), the horizontal scale L of an IPV anomaly and the vertical scale H of the RV anomaly it induces, are related by the formula for the Rossby radius of deformation: L is proportional to NH/f (PS I'd suspect that a more general relationship would replace f, the planetary vorticity, with the basic state AV ?). or H is proportional to L*f/N N is the buoyancy frequency (basic state) and I believe it is proportional to the square root of stability (where stability = 1/S). I explained why static stability limits vertical penetration of induced RV (Bluestein p.193 - specifically H is proportional to the square root of S). How would the length scale work? Well, conceptually, for a given static stability, the horizontal temperature gradient increases with increasing slopes of isentropic surfaces. The thermal gradient must balance the vertical shear that limits the vertical extent of the RV. A given slope over longer horizontal distance implies a greater vertical displacement of an isentropic surface relative to basic state conditions. --- An IPV anomaly distorts the isentropes from their basic states; the greatest distortion being closest (in vertical and horizontal) to the IPV anomaly center. For a cyclonic IPV anomaly, isentropes are 'pulled' upward towards it from below and downward from above. Notice that if this anomaly is moving, say, eastward relative to the air above and below, adiabatic motion above and below, in response to the passing IPV anomaly, follows the isentropes; as the IPV anomaly approaches, what happens is (mostly?) as described in the second long paragraph of comment 313, which started "Now what happens when there is vorticity advection that varies with height?". There is convergence at levels above and below, vertical motion toward the level of the anomaly; the reverse happens as the IPV anomaly passes and moves away. What about if the IPV anomaly is moving differently with respect to the air above and below? If there is westerly (eastward) shear throughout, the air above approaches the IPV anomaly from the west. Thus what happens above the IPV anomaly is reversed east-to-west from what was described above. In that case, vertical motion is downward both above and below the IPV anomaly level to the west and upward both above and below to the east of the anomaly. Looking only in a planar cross section, it would appear that the air only approaches the level of the anomaly and then moves back; however, the air also moves around the anomaly cyclonically; if there is a basic state temperature gradient - warmer to the south - then the isentropes slope upward to the north, so for example, the air below the IPV anomaly to it's east, approaches the IPV anomaly and rises, and moves north; The northward motion may not slope up as much as the isentropes because it pushes the isentropes with it (horizontally-concentrated warm air advection - creating eddy potential energy from basic state potential energy), but it may slope in the same sense to some degree, allowing some air to rise above the IPV anomaly level while to it's east (after having moved into colder surroundings, so that it is rising in a thermally-direct fashion (out of a dent in the isentropic surface created by the horizontal motion): eddy potential energy converts to eddy kinetic energy); it then (with some geostrophic adjustment) accelerates to the east with the upper level air. And so on for the sinking motion west of the IPV anomaly. Throw in tilting anomalies with height, etc...: A growing baroclinic wave (extratropical cyclones). Now if there is a basic state IPV gradient, then the IPV anomaly may propagate against the wind, ... etc... Especially if the wavelength of the anomaly is large... (It would be interesting to consider how variations in N, H, wind shear, IPV gradients, AV, and wavelengths combine to determine whether a baroclinic wave can grow and how fast). Actually, much of the isentropic IPV gradient (besides that 'at the surface' ?) is concentrated near the tropopause and stratosphere; for isentropic surfaces that cross the tropopause, the stratospheric portion can be judged as the region with larger IPV. My impression is that some of baroclinic instability can be understood in terms of undulations in the tropopause corresponding to tropopause level IPV anomalies, and surface temperature variations corresponding to IPV anomalies 'at the surface'. But there is some basic-state IPV gradient (increasing toward the poles generally) within the troposphere).
129412. chris at 11:43 AM on 10 November 2008
        Evaporating the water vapor argument
        Yes there is a limit to incoming electromagnetic radiation. I expect that there is an upper temperature limit. Perhaps Venus might give us a clue as to the upper temperature limit that is possible due to the "amount of energy that can be "retained" by GG effects". And yes, we might very well not find that to our liking. Of course GG's are "adding" something. They are adding thermal energy to the Earth's atmosphere, surface and oceans.
129413. chris at 11:35 AM on 10 November 2008
        Water vapor is the most powerful greenhouse gas
        nope, you're still not getting it. First of all I did say that the tiny excess amount of water vapour with its short residence time might have an effect, but this will be a small steady state one, since the excess water vapour rather quickly precipitates from the lower atmosphere. In post #14 we calculated that the steady state effect might be equivalent to something under 1 ppm of additional atmospheric CO2. Remember that atmospheric CO2 doesn't fall out of the atmosphere. As we pump CO2 into the atmosphere it accumulates day by day, month by month, year by year. That can't happen with water vapor. So any tiny additional amount of water vapour we pump into the atmosphere that supplements that vastly larger amount from natural evaporative/precipitation results in a tiny steady state increase in whatever amount of warming results from the natural evaporation. Of course we do know that as the troposphere warms throughout its entire height, so the saturation point of water vapour increases (warmer air holds more water vapour). And so there is a net accumulation of water vapour in response to CO2-induced atmospheric warming that does lead to a cumulative increase in atmospheric water vapour. We know this occurs, first because it's simple physics and secondly we can measure it in the real world. In short: ONE: the CO2 we pump into the atmosphere stays there (except for the amount that partitions into the oceans and is absorbed by the terrestrial environment). Therefore atmospheric CO2 concentrations rise cumulatively (and very very quickly now). TWO: the water vapour that we pump into the atmosphere is a tiny supplement to the natural evaporative/precipitation cycle, and since this comes straight out of the lower atmosphere within a week or two it can (a) have only a very small effect and (b) caanot be cumulative. THREE: AS the entire troposphere warms under the influence of cumulatively enhanced CO2 concentrations, so the atmospheric water vapour concentration rises. This element (the water vapour feedback to enhanced greenhouse warming) is cumulative, and does provide a very significant supplement (a feedback or amplification) to the primary CO2-induced warming.
129414. chris at 11:18 AM on 10 November 2008
        It's Urban Heat Island effect
        How silly Mizimi. We're not taking a picture of you in Times Square. We're taking a picture at night of the cities and built up areas of the Earth. If we "left the camera running and took 365 photos on ONE frame", the lights of New York and the great connurbation of the Eastern US seaboard are NOT going to disappear are they? ..and nor will the lights of the great cities and connurbations spreading Westwards from the East coast....nor the cities of Western coastal USA...nor the great built up areas down the East coast of South America (Rio; Buenos Aires...)...nor the great cities and connurbations of Western Europe...nor the equivalent cities and connurbations of Japan and the East and S. east coast of China...nor the cities and connurbations scattered around the inhabited coastal regions of Australia...and so on... ...and lights are not magically going to appear in Arctic and Alaska, the vast Northern territories of Canada and Serbia, the empty regions of Australia, North and Central Africa and so on... The Urban Heat Effect is by definition an URBAN heat effect. Urban areas are identifiable by night time satellite photos since they are lit up. The greatest density of light relates to the greatest density of urban infrastructure. The rather obvious conclusion from John Cook's juxtaposition of global surface temperature anomaly and nightime satellite image is that most of the vast areas of the world that have undergone rather large warming in the years to 2005 are those that are very far away indeed from urban centres. In fact one doesn't really need John Cook's night time satellite photo to make that conclusion. One only needs to inspect the global surface temperature anomaly image with a reasonably informed understanding of human population geography to see that the urban heat effects can't have made significant contribution to global surface warming... ...but the satellite photo is an excellent aide to those that might not be too clued up on the geographical distribution of industrialised human populations. ...and it's a beautiful photo, so kudos to John Cook for a very informative juxtaposition...
129415. chris at 06:59 AM on 10 November 2008
        It's the sun
        re #202 You need to explain your request. All 13C is "natural" (unless it's produced in a particle accelerator). What do you mean by the "current source of 13C" and the "natural source of 13C"? And what "catalysts" are you referring to? 13C is a carbon isotope and isn't affected by catalysts.
129416. Mizimi at 06:40 AM on 10 November 2008
        Water vapor is the most powerful greenhouse gas
        1. The WV does indeed mostly stay in the lower atmosphere, but since that is the nearest to the radiating body ( the earth)it has a proportionately greater effect (exponential? the first molecule radiates in all directions and some of that is captured by the next and et seq) and whilst the amount may be small in relation to the total, the same can be said for CO2. And you don't appear to accept that when that WV is in the atmosphere ( for however long) it IS achieving some level of greenhouse effect. 2. The WV column thro' the atmosphere is a gradient, most at the bottom of the column. This re-inforces my view that its greatest effect is at lower levels. The current amount of WV being 'added' by man is larger than the CO2 and logically has a greater warming effect. 3. With regard to the absorbtion of IR I will go re-check. But by your figures there is 5x more WV than CO2 and together they account for a 33C rise in temp. This makes WV twice as powerful as CO2. 4. I have preliminary data on world water usage which shows a rising trend from 700 to 2000 cubic kilometres from 1950 t0 2005 - - this is evaporated water from all sources. Interestingly there is a marked increase from 1980 -1990 of around 30% ( 1850 to 2360 ck)just around the time the GMT started to rise sharply. I don't see this as co-incidence.
129417. Patrick 027 at 06:33 AM on 10 November 2008
        Arctic sea ice melt - natural or man-made?
        Wrapping up some details: To be precise, IPV is equal to the negative of the isentropic AV divided by dp/d(theta) * 1/g, where g is the acceleration due to gravity, theta = potential temperature. (Bluestein p.190) Let S = dp/d(theta), so S is inversely proportional to static stability. IPV = - AV * g/S. S/g is actually the mass per unit theta per unit area, and so this formulation of IPV is equal to AV per unit mass per unit area within an isentropically-defined layer. To make comparable to barotropic PV, we could let barotropic PV = AV * g/(surface pressure); this is AV per unit mass per unit area of the whole fluid layer; or for a nearly incompressible fluid like water, barotropic PV = AV/(H*density), where H is the depth of fluid.
129418. Quietman at 02:48 AM on 10 November 2008
        A Great Science Fiction Writer Passes - Goodbye Dr. Crichton
        The 13th Warrior (Eaters of the Dead) was my favorite movie but I had some trouble getting into the book. Jurrasic Park my favorite book by him (the movie was good but not as). Then there was Prey and State of Fear, both excellent but somewhat alarmist.
129419. Patrick 027 at 14:51 PM on 9 November 2008
        Arctic sea ice melt - natural or man-made?
        I did several internet searches a week or two ago on the subject of annular modes, waves, and troposphere-stratosphere interaction. Here's what I remember at the moment: The stratosphere can have an effect on the troposphere (besides thermal/radiative). Conditions in the stratosphere affect how or if various waves in the troposphere can propagate. But conditions in the troposphere affect those waves - their production, etc. Annular modes may/might occur due to tropospheric mechanisms even without stratospheric feedbacks. But the stratosphere can play a role. A component of climate change 'projects onto' the annular modes - An aspect of the climate change with global warming is similar to a change in the AO or NAM index (NAM = Northern Annular Mode, I think; and I think it's the same as the Arctic Oscillation, AO). Cliamte change may affec the relationship of NAO to NAM. Ozone depletion affects SAM? From my own simple logic, I would guess the direct thermal response of the stratosphere to solar forcing would be (besides a generally warmer stratosphere and above) a warmer summer and low-latitude upper stratosphere relative to the winter polar stratosphere; whereas increasing CO2, etc, should (aside from generalized cooling) tend to cool those parts that are warmer relative to other parts - thus, the lower stratosphere of midlatitude winter would cool relative to the low-latitude and high-latitude parts of the same. The cold winter polar stratosphere would be relatively warmer in comparison. HOWEVER, from IPCC graphs (Ch 9 in AR4 WGI, as I recall), the modelled distribution of the temperature response (aside from the marked difference in the overall trend) is more similar between solar and GHG forcing. Must be the dynamic feedbacks...but how do they work? If the stratosphere can affect the troposphere, then perhaps the mesosphere can affect the stratosphere, and so on (well, of course they do, it's just a question of in what way and the significance of it). Changes in solar forcing have a large effect on the thermosphere in particular. On the other hand, I've gotten the impression that observations so far indicate a multidecadal (?) thermospheric cooling, along with the stratosphere and mesosphere, suggesting GHG forcing has been dominating the trend even up there. So the solar UV and shorter wavelengths and other energies may have a 'special' role to play by way of troposphere-stratosphere-etc. interaction, but I don't see a reason to suspect it explains a sizable chunk of what would otherwise be attributed to GHGs, etc..., at least and especially the later part of the 20th century - but then again, there is a lot I haven't read and don't know. (and what about winds and currents in the ionosphere?) So if you find something... (but remember how much work supports the conclusion that GHG forcing has been dominant).
129420. Patrick 027 at 14:27 PM on 9 November 2008
        Arctic sea ice melt - natural or man-made?
        I think one necessary condition for both barotropic and baroclinic instability is that the waves/eddies have to be moving such that there is at least one level (in the horizontal or in the vertical, respectively) - a critical level - at which the basic state wind is moving with the instability phase speed. --- waves can grow, propagate, be emitted by a disturbance, reflect, refract, absorb, over-reflect (I think that's analogous to stimulated emission of radiation), and also, they can break. I think breaking occurs when material lines reconnect (which requires mixing) *?*. Notice that for adiabatic motion, contours of IPV on an isentropic surface are material lines on that surface. They are also isentropes on an IPV surface, and those are also material lines on an IPV surface. Reconnection of these contours can result in cut-off eddies (like a cut-off low); this can occur from diabatic processes which can produce and destroy IPV. Waves can also interact and produce waves in other parts of the spectrum or produce disturbance that radiate other waves, etc... ---- On wave-mean interaction: Earlier I discussed interaction between barotropic Rossby waves and variations in the basic state wind, such as westerly jets and relative minimums in the westerlies (or, alternatively, easterly jets). It wasn't clear to me what actually happens, but here's another way of looking at it: The anomaly wind field has u' and v'. If the anomaly consists of a wave train of symmetric cyclones and anticyclones, which are superimposed on some basic state, then the average u'v' is zero. But suppose the basic state is a westerly jet. The total state may then be a meandering westerly jet (with troughs and ridges). But, if the advection is stronger than differential Rossby wave propagation (?), the basic state will distort the anomalies; it tends to tilt the waves- the troughs and ridges tilt from SW to NE to the south of the jet and from the NW to the SE to the north. This tilt cause a nonzero average u'v', which is positive to the south and negative to the north, which means that eddy zonal momentum is being transported by eddy meridional momentum and the transport converges toward the jet, so that zonal momentum is being added to the jet. Whether this means the jet accelerates or the jet widens (or if the jet narrows?), I'm not clear. Notice that (if the jet is accelerating - I think it does, actually) this also increases cyclonic RV to the north and anticyclonic RV to the south of the jet; there is a relationship between eddy momentum convergence and eddy vorticity flux; there is also a relationship between EP flux convergence and eddy IPV flux (EP flux is a vector with vertical component determined by eddy temperature flux v'T' and meridional component determined by eddy momentum flux u'v'; increasing v'T' with height increases stability to the north; decreasing u'v' to the north is proportional to a northward flux of eddy cyclonic RV: v'RV'). There are mechanisms by which jets may sharpen themselves. (see links from http://www.atm.damtp.cam.ac.uk/people/mem/ ) Also, mixing of IPV or PV in general can/may lead to a 'PV staircase' because mixing between two contours of PV and mixing between two other contours of PV, in reducing the PV gradient in two regions, must then increase the gradient in between such regions. This has consequences for jets. A paper on this - "Multiple jets as PV staircases: the Phillips effect and the resilience of eddy-transport barriers" - is also linked from the above website. It is analogous (according to that paper) to mixing of potential density or temperature in a vertically stratified fluid - mixing can give rise to regions with even sharper density contrasts (I think it's called the Phillips effect). Perhaps not quite the same thing (because it's not multiple layers) but the mixing of the upper ocean, by cooling the surface and warming the bottom of the mixed layer, produces a thermocline - a sharper temperature gradient - at the base of the layer. The strong stratification in the thermocline makes it harder to mix additional water from below into the upper layer (it is also harder to vertically mix the air across an inversion, such as when the air near the surface cools at night - the vertical wind shear can cause mixing by way of a shear instability (Kelvin Helmholtz instability, I think) (which I think is analogous the barotropic instability in horizontal shear), but the stronger the stratification, the stronger the wind shear has to be before such mixing can commence (see also "Richardson number"); I only started reading that PV-staircase paper but I think it was a point of the PV-staircase concept that the sharpened PV gradients become an impediment to further horizontal mixing). In the lower atmosphere, mixing of the boundary layer (layer nearest the surface, unless one differentiates between that and a much thinner 'surface layer') can be driven both by kinetic energy input from wind shear-related instability, and by thermally-driven convection when heated from below (daytime over land, cold front passing over warm water); the thermally-driven convection also produces kinetic energy and the kinetic energy can be used to mix further upward into stable air above, which can produce a thicker boundary layer capped by a strongly stable layer such as an inversion, which resists further mixing. AND NOW FOR AN APPLICATION OF WAVE-MEAN INTERACTION: "Wave-maintained annular modes of climate variability" "HARTMANN Dennis L." "Abstract The leading modes of month-to-month variability in the Northern and Southern Hemispheres are examined by comparing a 100-yr run of the Geophysical Fluid Dynamics Laboratory GCM with the NCEP-NCAR reanalyses of observations. The model simulation is a control experiment in which the SSTs are fixed to the climatological annual cycle without any interannual variability. The leading modes contain a strong zonally symmetric or annular component that describes an expansion and contraction of the polar vortex as the midlatitude jet shifts equatorward and poleward. This fluctuation is strongest during the winter months. The structure and amplitude of the simulated modes are very similar to those derived from observations, indicating that these modes arise from the internal dynamics of the atmosphere. Dynamical diagnosis of both observations and model simulation indicates that variations in the zonally symmetric flow associated with the annular modes are forced by eddy fluxes in the free troposphere, while the Coriolis acceleration associated with the mean meridional circulation maintains the surface wind anomalies against friction High-frequency transients contribute most to the total eddy forcing in the Southern Hemisphere. In the Northern Hemisphere, stationary waves provide most of the eddy momentum fluxes, although highfrequency transients also make an important contribution. The behavior of the stationary waves can he partly explained with index of refraction arguments. When the tropospheric westerlies are displaced poleward, Rossby waves are refracted equatorward, inducing poleward momentum fluxes and reinforcing the high-latitude westerlies. Planetary Rossby wave refraction can also explain why the stratospheric polar vortex is stronger when the tropospheric westerlies are displaced poleward. When planetary wave activity is refracted equatorward, it is less likely to propagate into the stratosphere and disturb the polar vortex. " http://cat.inist.fr/?aModele=afficheN&cpsidt=962252 This is far from the only paper on the subject. I couldn't begin to get into all of it.
129421. Patrick 027 at 12:51 PM on 9 November 2008
        Arctic sea ice melt - natural or man-made?
        Another view - back to (x,y,p) coordinates: What happens when there is either horizontal variation in temperature advection, or in diabatic heating? Answered earlier (way way back in "Science and Society", I think): relative warming or cooling changes the vertical geostrophic wind shear, and the resulting ageostrophic wind leads to divergence and vertical circulation where the warmed region rises (and adiabatically cools), the cooled region sinks (and adiabatically warms). Now what happens when there is vorticity advection that varies with height? Suppose there is a gradient in AV in the horizontal, and the wind blows partly along the gradient. Suppose this varies with height, so that relative to the rest of the air in a column, there is some vertical level in which air with lower AV is being replaced with wind with higher AV. Setting aside variations in planetary vorticity for the moment, this would mean increasing RV at that level. If the old RV value was balanced with the mass distribution above and below, the new RV won't be - if it is more cyclonic, the resulting cyclonic ageostrophic wind is accelerated by the coriolis effect to the right, which means outward from the center (horizontally); there is divergence. This removes mass from the column, lowering the pressure at all levels. If the initial change in RV had been imposed equally at all levels, the divergence would, conserving angular momentum, reduce the RV while increasing the geostrophic RV until they match (and then there might be some osciallation about equilibrium if the perturbation were imposed relatively suddenly, radiating inertio-gravity waves ?). But when the initial RV change occurs at one level, the divergence at that level increases the geostrophic RV at all levels, and this causes convergence to occur at all the other levels. The mass-continuity requires then that there is vertical stretching both below the level of initial RV change (let's call that p1) and above it, while there is vertical compression occuring at p1. Thus the maximum upward motion is at the base of the layer at p1 and the maximum downward motion is just at the top of that layer. This has adiabatic temperature changes associated with it. If the air had neutral stability, the adiabatic temperature changes due to vertical motion wouldn't change the horizontal temperature gradients, but with some vertical static stability, the cooling and warming produce relative cold and warm areas just below and above p1, which are most intense closer to p1. This temperature field acts to change the pressure field away from p1, so that farther above and below, there is a greater change in pressure that is opposite to that due to the initial divergence at p1. Thus the effect of the divergence at p1 to induce convergence above and below p1 becomes concentrated closer to p1 in the vertical. This is how higher static stability reduces at least some aspects of the dynamic interaction across vertical distances. Anyway, the RV is reduced at p1 and increased below and above, with the greater changes closer to p1, until balance is approached between the wind and mass field. The result is a relative RV perturbation that is maximum at p1, decreasing below and above, with colder air just below p1 and warmer air just above p1, which suggests an enhanced stability at p1. Notice what this implies for the vertical IPV distribution. Such interaction occurs in growth of baroclinic waves by baroclinic instability. Note that the vertical extent of the wind field corresponds to a vertical extent of temperature advection by that wind, producing a temperature anomaly. --------- Bluestein has a simple explanation that suggests that an IPV wave train in an IPV gradient (a Rossby wave in IPV) which is confined either horizontally (to being along a basic state IPV contour) or vertically, will initiate Rossby waves like itself that propagate away from itself horizontally or vertically, from where it was confined; moreover, when these waves initially develope, they act to destroy the initial wave, so that the result is two groups of waves propagating away in either direction (with the group velocity). - see Bluestein, pp. 214-216. --- Baroclinic and barotropic instability (or at least one kind of it ?) can both be explained as counterpropaging Rossby waves in an IPV context. (see Bluestein pp.207-208, see also Martin). 1. Baroclinic instability: Imagine that higher in the air, IPV increases to the north, but below some level, the IPV increases to the south (in the basic state). In that case, Rossby waves phase speeds are in the opposite direction above and below; to the west above and to the east below. If the basic state temperature increases to the south, the basic state vertical wind shear is to the east (westerly) going up, which reduces the phase speed of each set of Rossby waves relative to the other. What else can happen is that the vertical penetration of the wind field associated with each set of Rossby waves allows the Rossby waves above to induce waves below and vice versa. Because of the reversal of basic state IPV gradient, the result can under some conditions lead to two sets of waves that amplify each other and in that also tend to keep each other from moving relative to each other. The basic state IPV gradient is generally to the north down to the surface (although I wonder if regional east-west components might reverse with height?); however, the temperature gradient implies that isentropic surfaces slope downward toward the equator, which means that for any two isentropic surfaces, there is a point to the south (in the Northern Hemisphere) beyond which there is no more air in between them; they are at the same pressure, and the static stability is positive and infinite. Convergence toward a surface high temperature region 'inflates' the space between a pair of isentropes, and at the point at which the air arrives, it has some vorticity; convergence will increase that vorticity while conserving angular momentum, with vertical stretching (the 'inflation' of the space between isentropes). In this sense (I think), a surface warm temperature anomaly, which is associated with either cyclonic RV decreasing with height or anticyclonic RV increasing with height, is 'induced' by a cyclonic IPV anomaly at the surface, and the basic state increasing temperature to the south (in the Northern Hemisphere) implies a basic state IPV gradient at the surface with increasing cyclonic IPV toward lower latitudes. Notice that, relative to the wind at some height, the wind around a warm region at the surface, with the basic state temperature gradient just mentioned, will tend to pull warm air from low latitudes east of itself while pulling cold air from high latitudes west of itself, and thus the temperature wave propagates to the east (at least as far as phase speed is concerned). One complexity: this is relative to the vorticity at some height above the surface (although perhaps even if the wind rotated anticyclonically above a warm surface anomaly, it wouldn't propagate as fast to the west as it would if the the thermal gradient were reversed?). What if there is a reversal in the horizontal IPV gradient in some horizontal direction? The result can be qualitatively similary; one could have sets of counterpropaging Rossby waves which are able to amplify each other: Barotropic instability. Notice a Rossby wave can't continue to propagate into a region without an IPV gradient (there may be some evanescent wave would could allow tunneling of a portion of the energy through such a region if finite in size). The group velocity might reflect? If there is a critical level where the wind is moving with the phase speed of a Rossby wave embedded somewhere else but whose wind field reaches the critical level, energy can be exchanged between the wave and the basic state at the critical level (you can imagine that there would be ongoing motion at the critical level that is not propagating relative to the air there. I'm not sure exactly how this works, though). Sharp changes in propagation at the tropopause (change in static stability, IPV and IPV gradient) and surface - reflection? refraction? etc. (I'm still learning.) And so on. (I'm just about done with this here.)
129422. Patrick 027 at 11:46 AM on 9 November 2008
        Arctic sea ice melt - natural or man-made?
        Clarifications: ..."there is a process of geostrophic adjustment which radiates mechanical waves" - I think this generally involves radiating waves with frequencies greater than f/(2pi) - and would not involve Rossby waves (?), which are not fundamentally ageostrophic but rather 'quasi-geostrophic'. Of course Rossby waves may be produced but they do different things. "When the AV is anticylonic, there is inertial instability; this is an instability in horizontal motion." - with static stability, there is the buoyancy frequency N. When the square of N is negative (there's a mathematical formula with the square of N), N is imaginary; an imaginary frequency corresponds to instability, whereas neutral stability corresponds to N = 0. A real nonzero N occurs when the air is stable, meaning potential temperature increases with height; an adiabatic vertical displacement involves pulling or pushing up or down on an isentropic surface, creating a thermal anomaly whose buoyancy tends to push the isentropic surface bump or dent back. - with inertial stability, a horizontal displacment of air may put it in a location surrounded by air with different velocity. This is true when the velocity varies horizontally, so that there might be vorticity. Because the air parcel has a different velocity, while it is in the same pressure field as the air immediately next to it (for a small parcel), it has a different acceleration due to the coriolis effect, so it tends to move differently than it's surroundings. The effect is to push it back to where it was taken from, and so it can oscillate with a frequency; but when that frequency is imaginary, there is instability - the acceleration due to the coriolis effect acting on the different velocity actually pulls it farther away from it's initial position in that case. ---- Streamfunction: Streamlines, which are everywhere parallel to the non-divergent component of the wind, are actually contours of the streamfunction. Each component of the wind can have it's own streamfunction and they can be linearly added to give a total streamfunction for the total non-divergent wind (streamfunctions can't be defined for divergent winds). The streamfunction for the geostrophic wind is defined, in isobaric coordinates (x,y,p) as the geopotential (or the geopotential minus some average spatially-invariant geopotential) on an isobaric surface divided by f. Actually, though, because f varies with latitude, the geostrophic wind has a divergent component if there is any north-south velocity component, so the streamfunction as just defined is only approximate and I'm not sure if the streamlines would be everywhere parallel to the geostrophic wind in that case; one way around that is to pick some basic state f, f0, which is the value of f at some latitude where y is arbitrarily equal to zero, and use that to define the streamfunction; the actual f is then equal to f0 + y*beta (if beta is constant, which is also an approximation valid for some finite range of latitudes centered on y=0 - this approximation is referred to as a 'beta plane'). The effect of the variation in f is then incorporated into the equations as y*beta, etc. The streamfunction on an isentropic surface is the Montgomery streamfunction, which is equal to cp*T + geopotential (or that minus any constant) - where cp is the heat capacity per unit mass, and T is the temperature. Along an isentropic surface (both in space and time), T only varies as a function of p (pressure) (adiabatic temperature changes). Thus where an isentropic surface is parallel to an isobaric surface (the same condition where there is no vertical geostrophic wind shear), the Montgomery streamfunction is just proportional to the isobaric streamfunction. The cp*T term accounts for the variation of geostrophic wind with height in isobaric coordinates. At any given intersection of an isobaric surface and an isentropic surface (which is an isotherm on the isobaric surface or an isobar on the isentropic surface), the wind is the same; the difference in geostrophic velocity between two isobars on an isentropic surface is due to the sum of 1.the change in geostrophic velocity along an isobaric surface some horizontal distance, and 2.the change in geostrophic velocity that occurs going vertically from that isobaric surface back to the isentropic surface. The later is perpendicular to the slope of the isentropic surface in (x,y,p) coordinates...[**?? Notice that the geostrophic wind, if not for non-zero beta, would be non-divergent on an isentropic surface as well as on an isobaric surface (I think **).] The curvature of the streamfunction, or specifically, the Laplacian of the streamfunction, is proportional to the relative vorticity. The Laplacian is equal to the divergence of the gradient.
129423. Patrick 027 at 06:15 AM on 9 November 2008
        Arctic sea ice melt - natural or man-made?
        A few details: Rossby radius of deformation (written as if in a spreadsheet formula, sqrt(x) = the square root of x) external: sqrt(g*H) / f where g is the gravitational acceleration, H is the depth of a fluid layer, f is the planetary vorticity and also the coriolis parameter. internal 1.: sqrt(g'*H)/f where g' is g multiplied by the ratio of a density discontinuity to the density (the density of the lower layer). internal 2.: N*H/f N is the buoyancy frequency, H is the vertical extent of the fluid (or of a given phenomena within the fluid**?). The second internal radius of deformation is applicable to a continous stratification, typical of the atmosphere. The Rossby radius of deformation is the horizontal length scale for which the effects of rotation (coriolis effect) and stratification (stability) are similar. The radius of deformation could also be defined as N*H/(f+RV) = N*H/(AV). This has consequences for rotating disturbances such as a hurricane, where the rotation could be thought of as causing some additional coriolis effect with respect to features caught within the rotation. ---- For sloping isentropic surfaces: the geostrophic vertical wind shear projects onto isentropic surfaces as a component of the horizontal wind shear, and thus is part of the isentropic RV. It happens that this component of geostrophic isentropic RV is anticyclonic. If the isentropic surfaces are sloped steeply enough and the horizontal thermal gradient is great enough, it's possible that this anticyclonic contribution could dominate the isobaric RV and the planetary vorticity components of isentropic AV, such that isentropic AV is anticyclonic. In the absence of a horizontal pressure gradient and some nonzero RV, an ageostrophic wind will oscillate with the frequency of an intertial oscillation (= f/(2pi)). **But ageostrophic motions can change the mass and thus pressure distributions. So one can have inertio-gravity waves oscillating at some frequency (following that air) (which can be lower than the inertial oscialltion frequency) which propagate away from an initial disturbance. This relates to geostrophic adjustment - if there is an initial ageostrophic perturbation, there is a process of geostrophic adjustment which radiates mechanical waves. There will generally not be much of a remaining perturbation if the disturbance's horizontal extent was much less than the Rossby radius of deformation; on the other hand, some fraction of the intial perturbation's energy will remain in place as some feature in geostrophic balance for larger scale perturbations. Having a smaller effective radius of deformation in a tropical cyclone due to the cyclone's own rotation can enhance the trapping of pertubation energy. But back to inertial oscillations - what happens if there is some wind field so that a parcel perturbation's oscillating frequency is different. It turns out that the frequency of such an oscillation can be thought of as being in some way proportional to an inertial stability. I think that the frequency is AV/(2pi).** When the AV is anticylonic, there is inertial instability; this is an instability in horizontal motion. Inertial instability is analogous to vertical dry static instability - both are parcel instabilities whose essence can be understood by considering perturbing single air parcels (as opposed to hydrodynamic instabilities that require consideration of some larger-scale macroscopic organization) and both essentially don't occur, at least in larger scale conditions (and away from the surface for static instability) (or away from the lowest latitudes for inertial instability ??). What is more likely to occur or at least be approached, however, is a hybrid of the two instabilities, called symmetric instability. Symmetric instability occurs when the isentropic AV is anticyclonic (or when there is an unstable 'lapse rate' measured along surfaces of constant 'absolute momentum'), so that there is instability to slantwise motions; the stronger restoring force by far is typically that associated with static stability and N, so the overturning that can occur tends to be along isentropic surfaces. Or perhaps more likely, one may find conditional symmetric instability - analogous to conditional instability in the vertical - in which moist convection allows parcel trajectories to be sloped a bit more steeply than the isentropic surfaces. This kind of instability gives rise to some of the banding in precipitation associated with fronts. ---- Back to Rossby waves, the rest will be brief.
129424. Quietman at 04:48 AM on 9 November 2008
        It's the sun
        ps Re: "we don't evaluate the assertions of others using hero-worship or personal preferences" On the former it's not hero worship of Dr. Fairbridge but recognition of character and excellent work, and the latter is a resentment for the underhanded and demeaning treatment that Dr. Spencer receives for his skepticism.
129425. Quietman at 04:32 AM on 9 November 2008
        It's the sun
        You missed my point. So please explain how this natural source of C13 is different from the current source of C13 and how it is affected by catalysts.
129426. Patrick 027 at 17:14 PM on 8 November 2008
        Arctic sea ice melt - natural or man-made?
        I do want to round out the Rossby wave and vorticity subject matter: barotropic PV, isentropic PV, and mass distributions, static stability - the three dimensional fluid. For a geostrophic wind Vg, the coriolis force (or acceleration) is equal and opposite to the pressure gradient force (or acceleration); the coriolis acceleration magnitude is equal to the planetary vorticity f times the wind speed, in the direction to the right of the wind in the northern hemisphere, left in the southern hemisphere (or, since f is negative in the southern hemisphere, it could be described as a negative acceleration to the right of the wind velocity). The geostrophic wind is parallel to isobars on a geopotential or geometric height surface, or to lines of constant geopotential on an isobaric surface (PS note that either way they are the intersections of two sets of surfaces), the speed is proportional to the gradient of geopotential on an isobaric surface (p)or pressure gradient on a geopotential surface (geopotential = z*g, g is gravitational acceleration), and is thus inversely proportional to the spacing of isobars (x,y,z coordinates, spacing on a z surface) or geopotential contours (x,y,p coordinates, spacing on a p surface). It is also inversely proportional to (the absolute magnitude of) planetary vorticity f, since with a smaller f, a greater wind speed is necessary for the coriolis force to balance the pressure gradient force. Geostrophic wind is undefined at the equator (although I think it is possible (?) to define a geostrophic thermal wind - the vertical wind shear due to a horizontal temperature gradient - the key is to take the second spatial derivative of the temperature ...). The geostrophic wind blows cyclonically around low pressure and anticyclonically around high pressure. In x,y,z coordinates, the momentum equations are such that the pressure gradient must be divided by density to get the pressure gradient acceleration. In contrast, in x,y,p coordinates (pressure is p), there is no explicit density-dependence, so that the proportion of geostrophic wind speed to gradient of geopotential is constant for all p values (and there is no solenoidal term). The vector difference between the wind and the geostrophic wind is the ageostrophic wind. The ageostrophic wind can be large compared to the total wind at low latitudes and in smaller-scale features (thunderstorms). Generally, though, the geostrophic wind is close to the total wind for larger-scale motions at middle and high latitudes at sufficient height above the surface - with relatively bigger ageostrophic winds in frontal zones and around intense cyclones (due at least in part to centrifugal acceleration). Because the geostrophic wind is balanced with the pressure gradient, wind that is geostrophic won't accelerate (except for friction/mixing). Following the air as it moves (or even if it happens to stand still for a moment) the pressure gradient can/will change, causing an imbalance - an ageostrophic component, which allows and causes acceleration. Thus even if small, the ageostrophic wind is important. Generally, the ageostrophic wind (on large scales) makes up a 'secondary circulation' (which can involve horizontal divergence and vertical motion) which adjusts both the motion and the mass distribution (horizontal convergence, and vertical motion in pressure coordinates (or any change in pressure following the motion for any coordinate system) causes adiabatic temperature changes, and together this affects the mass distribution), tending to keep the wind and the pressure variation close to geostrophic balance, or else a gradient wind balance, where the centrifugal acceleration and coriolis acceleration due to the wind together balance the the pressure gradient acceleration (the centrifugal acceleration depends on the speed and the curvature of trajectories; trajectories can curve in the opposite direction of streamlines but a trajectory which 'stays with' a relative maximum or minimum in pressure will tend to curve the same way as streamlines (refer to last paragrarph of comment 302). This all assumes hydrostatic balance (gravity balances the vertical pressure gradient force), which is a very good approximation for at least the larger-scale motions. I'm not even sure that the atmosphere would deviate significantly from hydrostatic balance in high-frequency gravity waves (unless they have large amplitudes ?). But such deviation does play a role in the stronger thunderstorms. Hydrostatic imbalances account for vertical acceleration (which are very small for larger-scale motions). When the ageostrophic wind can have any value, there isn't a clear correspondence between vorticity and the mass distribution. But there is a relationship between geostrophic vorticity and the mass distribution (at least with the hydrostatic approximation). That relationship (for the following consider just a geostrophic wind and the geostrophic RV that comes with it): barotropic PV: relative vorticity (RV for this discussion) is cyclonic about low pressure, anticyclonic about high pressure (for pressure at a given z or geopotential). When the surface is flat (constant geopotential), the relative vorticity is correlated with the surface pressure in so far as local minimums or maximums are concerned, so that barotropic PV (proportional to AV/surface pressure) has a postive correlation to AV and anomalies of such PV have such correlations to RV. The relationship may be less clear-cut at some distance from any pressure maximum or minimum - although if one decomposes the pressure field into a basic state and some anomalies, one might again find some more clear relationship with the component of RV associated with the anomalies (provided the curvature **(the laplacian, which as an operator is the dot product of the gradient operatore with itself, equal to the sum of second derivatives in x,y,z, although in this context, just x and y)**, of the anomaly pressure field is positive where the pressure field anomaly is negative. This has to be true on the largest scale for continuity, but smaller wiggles or regions of constant gradients can go against this). When the surface has topography - variations in z, then the surface pressure is not entirely correlated to horizontal pressure variations; however the constancy of topography (on the relevant time scales) allows this topographic effect on barotropic PV to be considered analogous to the effect of planetary vorticity; a high plateau is analogous to higher latitudes. (A constant basic state surface pressure variation even in flat terrain could also be considered analogous to planetary vorticity variation - for example, the pressure variation due to the equilibrium paraboloid shape of the surface of water in a spinning dish.) Baroclinic fluid: isentropic PV (IPV) - The correlation between IPV variation and AV or RV variation is even less clear in general (to me, anyway - which is partly why I've been a little slow to pick up 'IPV thinking'). Barotropic PV is invariant in the vertical. IPV is not (generally). IPV is proportional to AV * [- d(potential temperature)/dp] - the negative of the vertical gradient of potential temperature in x,y,p coordinates (in stable air, d(potential temperature)/dp is itself negative, so using the negative of this allows a positive AV in stable air to have a postive PV). What would make for a clear-cut relationship is for a relative maximum in AV to correspond to a relative maximum in stability. Well, consider a relative maximum in cyclonic RV over vertical distance (which will correspond to a cyclonic AV anomaly since planetary vorticity doesn't have 'anomalies'). This means that below, cyclonic RV increases with height, and above, it decreases. If RV is geostrophic or nearly so, then that has implications for pressure variations. The greatest curvature (laplacian, d2/dx2 + d2/dy2) of the pressure field (along a horizontal plane) (or the greatest curvature of the geopotential field on an isobaric surface) must occur at the level of greatest cyclonic RV, decreasing away going down and up. The hydrostatic balance requires that the curvature of the temperature field (along either a z or a p surface, depending on chosen coordinate system) be positive below and negative above - that the thermal gradient (which points to warmer air) is divergent below and convergent above; if this is centered on relative maxima and minima, there would be (in the horizontal) relatively colder air surrounded by relatively warmer air below the cyclonic RV maximum, and warmer air surrounded by relatively colder air above the RV maximum. This implies that, if horizontally centered on temperature maxima/minima, the RV maximum is centered in the horizontal and in the vertical on a maximum in static stability. There will thus be, except for the planetary vorticity gradient, a relative maximum of IPV centered both in the vertical and horizontal on the RV maximum (provided planetary vorticity is cyclonic - which is always true). And if this is not actually centered on temperature maxima/minima? Well, the curvature (on either a z or p surface) of the stability must still be a maximum at the vertical level of the RV maximum and the RV maximum must be centered in the horizontal on the curvature of the stability (the convergence of the gradient of stability in x,y). The IPV maximum could be skewed to the side of RV if there is some component of the stability distribution that has a non-divergent gradient - the IPV maximum would be in between the highest RV value and the higher stability values. Also, it should be kept in mind that a relative cyclonic RV maximum doesn't necessarly occur with actual cyclonic RV - for example, if there is a strong enough anticyclonic RV above and below, the relative maximum in cyclonic RV could be a relative minimum in anticyclonic RV. It could still be a relative maximum in cyclonic IPV, though. As with barotropic PV, the correlation of IPV variations to RV variations could be made more clear by subtracting a basic state and then considering remaining anomalies (which themselves might be broken into components). PS as with barotropic RV in two dimensions, there is invertability with IPV; given sufficient boundary conditions (and a specification of the wind being geostrophic or in gradient wind balance), the wind field (or the specified component of it) and thus also the pressure field, can be determined, and the later also determines (again, with sufficient boundary conditions) the (potential) temperature field. (PS in the atmosphere, varyations in composition have relatively minor effects - when the specific humidity is quite high, then to be more accurate, a 'virtual temperature' can be found - this is the temperature that dry air would have to have to have the same density. In the ocean, salinity is of great importance, and so rather than considering potential temperature, one may consider potential density - the density the water would have if brought adiabatically (and without mixing or phase changes, though 'adiabatically' generally includes these constraints) to some reference pressure (such as at the surface).) There is also the consideration that IPV is evaluated based on the RV evaluated from the winds on an isentropic surface. Isentropic surfaces can slope considerably more than pressure surfaces, so some of the isentropic RV in (x,y,theta) coordinates (the greek letter theta is used to denote potential temperature) can come from vertical wind shear in either (x,y,p) or (x,y,z) coordinates. Also, purely non-divergent horizontal winds which vary with height, with no vertical motion in (x,y,p or z) coordinates, can, if a component of the wind shear is parallel to the horizontal temperature gradient (notice such a component must be ageostrophic), result in horizontal divergence or convergence and the accompanying vertical stretching in (x,y,theta) coordinates - note that adiabatic motion automatically has zero vertical 'motion' in (x,y,theta) because theta is constant following the motion; the vertical stretching is the increased seperation of isentropic surfaces in the z or p dimension. This happens because, even while the horizontal temperature gradient and thus x,y spacing of isentropes is invariant in this scenario, the isentropic surfaces are being tilted - if warm air advection decreases with height or cold air advection increases with height, then the isentropic surfaces are being taken from the horizontal and tilted toward the vertical. In the process, the projection of such a surface onto a vertical plane perpendicular to the thermal gradient is not changing in area if each such surface extends from top to bottom of whatever domain is considered (and the horizontal spacing of isentropes does not change), and so the horizontal component of isentropic RV does not change (however, if there is horizontal variation in the wind, the same may not be true of the actual vertical wind shear - since in this scenario the horizontal thermal gradient remains constant, the geostrophic wind shear remains constant, thus horizontal advection of the wind can produce an additional ageostrophic wind), but the horizontal projection of each isentropic surface (spanning a given vertical distance) is decreasing toward zero, and so (the vertical component of) isentropic RV increases toward infinity which conserving (the vertical component of) IPV as the vertical spacing (p or z) of isentropes increases to infinity (the stability goes toward zero); the volume between any two isentropic surfaces within a given vertical distance (p or z) is conserved (PS this is all assuming adiabatic and inviscid processes)...*****(may continue on that topic later) (PS note that the isentropes are not sloped in (x,y,p) where there is a relative temperature maximum or minimum in the horizontal). So the relationship between PV and RV can be complicated, but in general, a PV anomaly can be associated (co-located) with an RV anomaly of the same sign or vice versa. An IPV anomaly at a given vertical level will be accompanied by an RV anomaly field that extends both higher and lower than the IPV anomaly (the extent is reduced when static stability overall is higher** and also when the horizontal scale of the IPV anomaly (it's wavelength, for example) is smaller), and again the wind field generally extends farther horizontally than the RV anomaly itself. Thus if an IPV anomaly is confined either horizontally or vertically, it can, via the Rossby-wave propagation mechanism, propagate or initiate disturbances that propagate not only horizontally but vertically.
129427. at 16:07 PM on 8 November 2008
        Climate's changed before
        Conspicously absent from consideration of what could have caused the warming for the 30 year period is ENSO and PDO. Here is a 58 year ENSO chart. http://www.cdc.noaa.gov/people/klaus.wolter/MEI/ts.gif Notice that prior to 1977 La Nina dominates the chart. After 1977 El Nino dominates the chart. The dominance of El Nino corresponds with the temperature rise of the last 30 years. Climate scientist Dr. Roy Spencer has calculated that up to 70% of the temperature rise that we have seen could be accounted for by ENSO and PDO patterns. There also seems to have been a flip in the PDO cycle in the last year or so that could well indicate another 20 years of flat or negative temperature trends. By the way, you may notice that the El Nino dominance in the chart was greatest from about 1977 to 1998. After that the distribution is a little more even. This corresponds well to the flatening of the temperature trend for the last decade. While that point is also challenged in this blog, I have proven it to be true in the relevant section.
        Response: ENSO has been considered as a possible driver of global warming. The El Nino Southern Oscillation does show close correlation to global temperatures over the short term. However, it is unable to explain the long term warming trend over the past few decades.
129428. Philippe Chantreau at 15:37 PM on 8 November 2008
        What does CO2 lagging temperature mean?
        Actually,Mizimi, my readings suggest that low biodiversity is very likely to be associated with paucity of life, especially if the conditions undergo further change. Any state of low diversity is probably transient, manifesting a transition to a new equilibrium. It is not desirable for any life form to take over and overwhelm all other life forms. In fact, it does not seem that low diversity is something that commonly happens in the natural world. What should be especially concerning is decreasing biodiversity in a biome where there used to be a lot of diversity.
129429. saluki at 15:34 PM on 8 November 2008
        It hasn't warmed since 1998
        This one certainly is true now. There has been no warming for the past 11 years. Here is the chart for RSS, UAH, HadCrut3 and GISS. http://reallyrealclimate.blogspot.com/2008/10/updated-11-year-global-temp-anomoly.html Double click the chart to enlarge it. Also, when we correct for ENSO, the temperature trend remains virtually flat. Here is a chart comparing raw HadCrut3 with ENSO corrected HadCrut3. http://reallyrealclimate.blogspot.com/2008/07/gavin-schmidt-enso-adjustment-for.html As you can see, there is virtually no difference. The period in question had 7 ENSO event. 4 were El Ninos and 3 were La Ninas. Taken together they had almost no effect on the trend line.
129430. Patrick 027 at 14:43 PM on 8 November 2008
        Arctic sea ice melt - natural or man-made?
        "Arctic Sea Ice Is Suddenly Getting Thinner As Well As Receding" ... important example of the overall concept of thermal inertia / heat capacity and latent heat, or even more generally, any other aspect of climate inertia (sea water composition, vegetative feedbacks, etc.). "Less Ice In Arctic Ocean 6000-7000 Years Ago" The extent of the difference is news to me, but I think at least the Northern Hemisphere was warmer back then compared to more recent times (though maybe not anymore for the last decade or so? - we're getting into that territory). At least some of this longer-term change is caused by orbital (Milankovitch) forcing.
129431. Philippe Chantreau at 12:23 PM on 8 November 2008
        A Great Science Fiction Writer Passes - Goodbye Dr. Crichton
        I'll put "Rising Sun" on my list, John, thx for the tip.
129432. chris at 09:57 AM on 8 November 2008
        Water vapor is the most powerful greenhouse gas
        Not really Mizimi. Remember (see post #14/#20) that all we're doing is adding a small amount to the lower atmosphere which is a tiny proportion of that produced in the natural evaporation/precipitation cycle. We can blast and spray water into the atmosphere to our hearts content - it just comes out again. The warming effect of water vapour results from the column that exists through the entire atmosphere whose concentration responds dynamically to the atmospheric temperature and pressure. That's the greenhouse contribution: the amount of water vapour that is retained at equilibrium in relation to the atmospheric tempeature and pressure. By pumping a tiny excess amount of water vapour into the lower atmosphere, all we're doing is supplementing the already saturated amount that is there from the natural evaporation/precipitation cycle. I suppose that if one were able to measure this, there should be 0.05% more rainfall as a result! Water vapour isn't 10x more effective a GC than CO2. Despite the fact that the water vapour concentration of the atmosphere is 5 times that of CO2 (around 0.3% by mass for water vapour cf around 0.06% by mass for CO2), the contribution of CO2 to the greenhouse effect is at least 10% (and more like 25-30% with the water vapour feedback). Basically, over a period of a week or two a very tiny supplement of the natural evaporative water vapour cycle is added to the atmosphere from where it falls right out again. So if there is any additional contribution to the lower atmospheric water vapour this is a tiny steady state value that cannot increase.
129433. chris at 06:35 AM on 8 November 2008
        It's the sun
        No, that's not correct Quietman. Again you're using a paper to address an issue that is not, in fact, what the paper is about at all. The measure of 13C/12C ratios in CO2 in our environment is straightforward and shows a decrease as expected from the return of vast amounts of 13C-depeleted carbon into the atmosphere from long-sequestered fossil fuels originally derived from plant sources. That indicates very clearly that the massive enhancement of atmospheric CO2 (and that being forced into the oceans as a result) is from oxidation of fossil fuel (and a bit from deforestation) and doesn't significantly derive from tectonic activity. Which we know anyway, since we know how much CO2 we've produced during the industrial age, and can measure the increasing amounts in the ocean due to forced partitioning from the atmosphere. And of course we know from the high resolution 2000 year CO2 record and the lower resolution records spanning millions of years, that tectonic activity (volcanic or undersea sources)has made a trivial contribution to the net CO2 concentration. The paper that you cited [P.K. Swart (2008) Proc. Natl. Acad. Sci. USA 105, 13741-13745] is about something quite different. It addresses the mismatch between the apparently synchronous variations in 13C content of carbonate sediments deposited off the margins of low latitude shallow marine platforms and the pattern in the open oceans, and concludes that this difference can be resolved by noticing that the apparent synchrony relates to sea level changes and synchronous flooding of the platforms. So it's a paper that may have resolved an incompatibility between some marginal and deep ocean data sets. It doesn't have anything to do with the partitioning of carbon isotopes in fossil fuels and the readily measured variation in 13C/12C ratios that occur when 13C-depeleted carbon is returned to the biosphere by oxidation of fossil fuels. One should make an effort to find out what a paper is about before citing it in support of something on which it might have no bearing. Remember that science is all about the evidence, and the evidence should be appropriate to the issue at hand!
129434. chris at 05:52 AM on 8 November 2008
        A Great Science Fiction Writer Passes - Goodbye Dr. Crichton
        John, I wasn't really meaning the political situation as such (e.g. Reps/Dems!), but was referring more to the period in which widespread misrepresentation of the science by propagandising from many quarters had such a dismal (and anti-democratic) effect on public understanding of this issue. Sadly Michael Crichton got caught up in all of that. I think we're well over the worst of it and it's increasingly difficult for "skeptics" (!) to misrepresent the science with any conviction nowadays. But it seems appropriate to consider Michael Crichton's role as a misrepresenter of the science on global warming in the context of this web site, which has a theme of addressing "skeptical" misrepresentation. I wonder whether Michael Crichton would consider that he made a worthy contribution to the public's understanding of climate science and especially to the relationship between science and policy. It would be interesting to know why he chose the role he chose. In the end Crichton's role in this will probably be forgotten, and it's the films that he will be remembered for...a more worthy memorial.
129435. Mizimi at 05:38 AM on 8 November 2008
        Evaporating the water vapor argument
        Chris, you seem to have missed my point which is there is a limit to incoming heat and therefore a limit to the amount of energy that can be 'retained' by GG effects. So there is an upper temperature limit ( which we may not find to our liking) No? And yes, maybe I am playing with semantics but I don't see GG's 'adding' anything....only moderating the rate at which heat is lost.
129436. Quietman at 05:28 AM on 8 November 2008
        It's the sun
        chris I only recently posted a link to an article on how the whole 13C evidence needs a rethink. I think that I was addressing Mizimi in the Arctic Ocean thread when I posted it. Not sure now. We only thought we knew what we know on that one.
129437. chris at 05:05 AM on 8 November 2008
        Models are unreliable
        O.K. Dan, I think we're making some progress. It seems your "disagreement" with the science relates to a misunderstanding of the nature of "feedback" in relation to the earth's energy budget combined with a reliance on inappropriate analogies ("anti-missile missiles"; "cruise control devices"), a misunderstanding of insolation effects resulting from the cyclical elements of the earth's orbital properties that modulates the pattern of insolation on the 10's of 1000's of years timescale, and (judging by your previous posts and your dismal web page) a desire to impose a false view of this entire subject through a propagation of contrived misrepresentation. Is that "hostile"? Possibly...but I'd prefer "trenchant", since I think one should address contrived misrepresentation with a bit of vigour! Feedbacks. The evidence indicates that there is a NET positive feedback to enhanced atmospheric CO2 concentrations. You’ve said in another post somewhere that positive feedbacks occur with carbon dioxide and water. That’s exactly right. The warming effect of enhanced atmospheric CO2, for example, is amplified by a water vapour feedback, and certainly an albedo feedback. It seems that we agree about that. Overall the evidence indicates that the NET feedback results in a warming resulting from doubling of atmospheric CO2 of around 3 oC (+/- a bit). You seem to have a residual problem with this…I wonder whether it relates to your reliance on analogies and a textbook (Phelan, 1967) based on the analysis of control systems. Unfortunately feedbacks in relation to “control systems” are not really appropriate (see following): Dynamic systems/control systems. The climate is a dynamic system with elements involving forcings and feedbacks that "act" on many different timescales, as well as stochastic and non-stochastic elements that provide “noise” in various accessible parameters (such as the surface temperature anomaly). It differs from your notion of a “control system” in that the feedbacks are neither “designed” nor constrained to maintain an equilibrium, even if parameters (like the earth’s surface temperature anomaly) might well be in equilibrium for long periods as a result of a relatively steady state in relation to forcings (e.g. the sum of solar and greenhouse contributions). If there is a change in these forcings (a change in solar output or a change in greenhouse gas concentrations) the earth doesn’t respond so as to maintain an equilibrium surface temperature. The earth’s climate system evolves dynamically under the influence of the new forcings until a new (dynamic) equilibrium is reached. In the case of enhanced greenhouse forcing at constant insolation, the new equilibrium is around 3 oC of raised surface temperature per doubling of atmospheric [CO2]. There’s a NET positive feedback. Does the climate system have elements of your “control systems”. It does a bit. For example the vast oceans provides a heat reservoir that regulates surface temperature somewhat, both directly and through the evaporation/precipitation cycles. The vast ice sheets also provide a bit of a thermal “buffer” due to the large heat capacity associated with the ice/water phase transition. Over very long periods greenhouse-induced warming is countered by increased weathering that draws CO2 out of the atmosphere. But overall the earth isn’t really under the influence of “control systems” and certainly doesn’t respond in that manner. It responds to a change in forcings via dynamic transitions to new (dynamic) thermal equilibria. Milankovitch/feedbacks. I suspect you’re still confused by these. Variations in the earth’s orbital climatic precession, obliquity and eccentricity result in a rather complex, but well-defined variation in insolation that matches rather well the progression of temperature anomalies in the ice cores. I suggest that you look at some of the papers linked by John Cook here: http://www.skepticalscience.com/co2-lags-temperature.htm especially Petit et al, 1999 and Shackleton, 2000. If you have access to last week’s Nature magazine (6th November) read the paper on page 85 (Lisiecki et al (2008) “Atlantic overturning responses to Late Pleistocene climate forcings” Nature 456, 85-88.), or the accompanying commentary by Michael Crucifix “Climate’s astronomical sensors” on page 47. I know that you don’t like reading scientific papers and prefer weird websites and non-science magazines. However, one may as well obtain one’s information from the source that mature and well-informed policymakers source theirs! The significant NET positive feedback that amplifies CO2-induced warming relates to a relatively constant insolation. So in our present situation with a rather constant solar output and no significant Milankovitch contributions for many thousands of years to come, the enhanced greenhouse forcing is giving us (and will give us further) warming resulting from the earth’s climate sensitivity to enhanced [CO2] which the best evidence indicates is near 3 oC (+/- a bit) of warming for a doubled [CO2]. Obviously if the solar contribution diminishes either in relation to total solar output, or due to altered insolation patterns during Milankovitch cycles, the earth will still undergo cooling even ‘though there there is (a) a NET positive climate warming feedback to enhanced [CO2] under conditions of constant insolation, and (b) a residual highish concentration of atmospheric CO2 (since CO2 is drawn only very slowly out of the atmosphere).
129438. Mizimi at 04:58 AM on 8 November 2008
        It's Urban Heat Island effect
        The satellite photo shows cities at one point in time. The global anomoly picture is an average of a years data. If I stood in Times Square and you took a photo of me, I would clearly stand out. If you left the camera running and took 365 photos on ONE frame I would disappear...other things would get between me and the camera and obscure my image. This is what the GA picture does to UHI effects.
129439. John Cross at 04:34 AM on 8 November 2008
        A Great Science Fiction Writer Passes - Goodbye Dr. Crichton
        Chris: That was part of a nasty little period in US history, the worst of which has happily passed; I suspect (and hope) that you are correct. It will be interesting to see what the US does about climate change under Obama. I suspect that the current economic problems will lead to an automatic GHG reduction - but not in a way desirable. However I suspect that our good host would call that off topic and I would not want to see this thread devolve into a political thread. Philippe: Good authors all. I will also note that T.J. Bass is a medical doctor like Michael Crichton. One of the things that I found impressive about Crichton is that he was able to use technology in works that you wouldn't normally think of as science fiction. For example Disclosure (which I did not really like) and Rising Sun (which I did). Regards, John
129440. Philippe Chantreau at 03:44 AM on 8 November 2008
        A Great Science Fiction Writer Passes - Goodbye Dr. Crichton
        Fair enough. I'm not so much a fan of Crichton when it comes to Science Fiction writing. I think that Asimov, Heinlein, Ted Sturgeon, John Brunner, Van Vogt, Philipp K Dick, and others have works that are more interesting. Like Norman Spinrad short stories too. My all time SF favorite remains T.J. Bass' "Godwhale," which I warmly recommend to anyone who is into the genre. Crichton's Jurassic Park pieces were a lot of fun to watch on film.
129441. Mizimi at 03:30 AM on 8 November 2008
        Water vapor is the most powerful greenhouse gas
        But whilst that WV is in the atmosphere it is acting as a GG and thus delaying heat emission by the earth. The actual amount of 'natural' WV is increased by the addition of WV from man's activities and so the overall warming effect must be enhanced...after all is that not the argument for CO2? And WV is 10x more effective a GG than CO2. Unless one accepts there is a 'saturation' limit beyond which no further GG additions has an effect. Also if you add in the other sources of manmade WV (allowing 600B tonnes for agriculture)) we put more than 1000 billion tonnes a year into the atmosphere, which is 1 x 10^15 kg....0.2% My overall point here is that the amount of AWV has been increasing post 1950 ( the actual amounts I have yet to research) and the effect of that increase has to be included in any modelling.
129442. chris at 01:50 AM on 8 November 2008
        A Great Science Fiction Writer Passes - Goodbye Dr. Crichton
        Yes that's a pretty fair appraisal. Michael Crichton should be remembered for his excellent early science fiction and the outstanding films that flowed naturally from several of his best books. The ideas and solid writing completely lended themselves to top quality and thought-provoking films. The Andromeda Strain was an awesome film (I hadn't realised that it was a Michael Crichton based-piece). So kudos to Crichton. And not only would I echo your sentiment that he should be remembered for this body of work, I'm pretty sure that he will be. I also agree that we shouldn't forget the travesty of his "State of Fear", and more specifically the political mileage that was made of that dreary and scientifically-illiterate polemic, and the manner in which dismal vested interests elevated Crichton the novelist to the status of some sort of an "expert" on climate-related matters! In my opinion the manner in which Crichton's fantasy was puffed up to assume the guise of reality, ultimately did Crichton a disservice. That was part of a nasty little period in US history, the worst of which has happily passed; Michael Crichton's legacy will be the books and especially the films that resulted, and quite right too!
129443. chris at 20:03 PM on 7 November 2008
        It's the sun
        Re #195 Yes, we do know that an insignificant amount of this massive amount of CO2 that is being pumped into the atmosphere and absorbed by the oceans comes from volcanic/tectonic activity. We do know that the vast bulk of this is from burning fossil fuels (with a bit from forest burning). Remember that fossil fuels are highly depleted in 13C, since the plants from which the fossil fuels are derived select the 12C isotope for incorporation into their (initially) generic carbohydrate [(CHOH)6]. On the other hand oceanic subducted carbonates released by tectonic activity is indifferent to the isotopic composition of the carbon in the CO2 from which it is "fixed". So as fossil fuels are burned, they release their 13C-depleted carbon back into the atmosphere, and the 13C content of the CO2 in our environment drops. This is easy to measure in the real world (the 13C/12C ratio) using a mass spectrometer. The 13C content of CO2 in our environment is dropping just as expected from a fossil fuel source of CO2, as the atmospheric CO2 content rises dramatically in response to our massive rate of oxidation of long-sequestered fossil fuels There's lots of information on this of course! See, for example: Francey RJ, Allison CE, Etheridge DM, et al. (1999) A 1000-year high precision record of delta C-13 in atmospheric CO2 TELLUS B-Chem Phys. Meteor 51, 170-193 and D. M. Etheridge et al (1996) "Natural and anthropogenic changes in atmospheric CO2 over the last 1000 years from air in Antarctic ice and firn J. Geophys Res. 101, 4115 -4128 and so on...
129444. chris at 19:45 PM on 7 November 2008
        Water vapor is the most powerful greenhouse gas
        O.K., 25 billion tons of water vapour released in cooling towers and a bit more from other activities. Thta makes more sense. Let's use your 25 billion tons number and see whether this is significant in any way with respect to greenhouse gas warming. The answer is no...not really. This relates to the fact that water vapour in the atmosphere comes to a fairly fast equilibrium with respect to the atmospheric temperature and pressure (see my post #14). A good handle on this can be gleaned from a comparison of the water vapour released from cooling towers (and from fossil fuel burning overall) in relation to the overall amount of water vapour produced in the natural evironment by evaporation and precipitation. So we can use your numbers and compare the 25 billion tons of water vapour you indicate is released per year: 25 x 10^9 tons = 2.5 x 10^13 kilograms of water to the total amount of evaporation/rainfall worldwide per year: 5 x 10^17 kilograms of water. In other words the excess water vapour released into the atmosphere by the cooling tower/fossil fuel burning is around 0.005% of that released and precipitated yearly during the natural evaporative water cycle each year. in other worlds insignificant.
129445. Quietman at 15:43 PM on 7 November 2008
        Volcanoes emit more CO2 than humans
        2004 Indian Ocean Tsunami Biggest in 600 Years turns out to be more evidence of tectonic upset.
129446. Quietman at 15:39 PM on 7 November 2008
        Arctic sea ice melt - natural or man-made?
        Earth's Climate - Past and Future - William F. Ruddiman This sounds like what I am looking for. I don't want to study for exams, just do some light reading on subjects of interest. Thanks ps You might find this interesting: ScienceDaily (Nov. 3, 2008): Arctic Sea Ice Is Suddenly Getting Thinner As Well As Receding "The research - reported in Geophysical Research Letters - showed that last winter the average thickness of sea ice over the whole Arctic fell by 26cm (10 per cent) compared with the average thickness of the previous five winters, but sea ice in the western Arctic lost around 49cm of thickness. This region of the Arctic saw the North-West passage become ice free and open to shipping for the first time in 30 years during the summer of 2007." and also from ScienceDaily (Oct. 20, 2008) Less Ice In Arctic Ocean 6000-7000 Years Ago Both interesting.
129447. Patrick 027 at 15:37 PM on 7 November 2008
        Arctic sea ice melt - natural or man-made?
        There was a book called "Supercontinent" I saw a few months ago in the library; I think that had a little paleoclimate in it (PS I couldn't claim to have actually read through all or most of these books; some I've gone through for specific chapters/sections/topics...). "Cambridge Encyclopedia of Earth Sciences" (which, depending on library, may be checked out despite it's name) is another good one, though a bit 'old' (1980?), but covers a LOT (and it's BIG - I think somewhere around 1000 pages). If you're at the library, I'd suggest also Encyclopedia Britanica - I think they had articles such as "Climate and Weather", "Atmosphere", "Earth"; I forget which article it was in but a great section on the magnetosphere, too. If your library has McGraw-Hill Encyclopedia of Science and Technology, that's a good one too... well now I'm probably just giving you stuff you could easily have found by yourself. With many of the books I mentioned being textbooks, of course your best bet would be a college library. I should mention, I only remember or know of Rossby waves being discussed in the first four that I mentioned (Holton, Cushman-Roisin, Bluestein, Martin) and I think the first three of those have the most coverage of the subject.
129448. Quietman at 15:30 PM on 7 November 2008
        It's the sun
        Mizimi They might make it in blue, I know they make it in colorless, green and amber. I guess that the colorless translucent is the way to go then. PVC isn't strong enough, the snow and ice would break it before I could clear it off, in this area fibreglass is used for strength. I appreciate the suggestions, thanks. PS Just finished reading this one: Sunlight Has More Powerful Influence On Ocean Circulation And Climate Than North American Ice Sheets from ScienceDaily (Nov. 6, 2008).
129449. Mizimi at 09:32 AM on 7 November 2008
        Water vapor is the most powerful greenhouse gas
        PPS; the figures don't include WV from combustion ( all sources of), commercial airconditioning systems, fogging systems, domestic irrigation, or simple respiration ( human component expected to increase by 50% by 2050)
129450. Mizimi at 09:27 AM on 7 November 2008
        What does CO2 lagging temperature mean?
        Low biodiversity is not the same as a paucity of life. Some lifeforms will flourish under conditions which cause others to perish. As an aside....we have the ability to conduct experiments at CO2 and temp levels intimated by the paleoproxy records....I wonder if anybody is??

Prev  2581  2582  2583  2584  2585  2586  2587  2588  2589  2590  2591  2592  2593  2594  2595  2596  Next