For those who love (or hate) GISTEMP‘s surface temperature product, we have this from Climate-Skeptic.com, by Warren Meyer. His interesting analysis is timely and appropriate. Surface station coverage in the areas of greatest contention right now are rather poor. – Anthony
Warren writes:
Apropos of my last post, Bob Tisdale is beginning a series analyzing the differences between the warmest surface-based temperature set (GISTEMP) and a leading satellite measurement series (UAH). As I mentioned, these two sets have been diverging for years. I estimated the divergence at around 0.1C per decade (this is a big number, as it is about equal to the measured warming rate in the second half of the 20th century and about half the IPCC predicted warming for the next century). Tisdale does the math a little more precisely, and gets the divergence at only 0.035C per decade. This is lower than I would have expected and seems to be driven a lot by the GISS’s under-estimation of the 1998 spike vs. UAH. I got the higher number with a different approach, by putting the two anamolies on the same basis using 1979-1985 averages and then comparing recent values.
Here are the differences in trendline by area of the world (he covers the whole world by grouping ocean areas with nearby continents). GISS trend minus UAH trend, degrees C per decade:Arctic: 0.134
North America: -0.026
South America: -0.013
Europe: 0.05
Africa: 0.104
Asia: 0.077
Australia: -0.02
Antarctica: 0.139
So, the three highest differences, each about an order of magnitude higher than differences in other areas, are in 1. Antarctica; 2. Arctic; and 3. Africa. What do these three have in common?
Well, what the have most in common is the fact that these are also the three areas of the world with the poorest surface temperature coverage. Here is the GISS coverage showing color only in areas where they have a thermometer record within a 250km box:
The worst coverage is obviously in the Arctic, Antarctica and then Africa. Coincidence?
Those who want to argue that the surface temperature record should be used in preference to that of satellites need to explain why the three areas in which the two diverge the most are the three areas with the worst surface temperature data coverage. This seems to argue that flaws in the surface temperature record drive the differences between surface and satellite, and not the other way around.
Apologies to Tisdale if this is where he was going in his next post in the series.
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Annabelle (03:29:00) That single observation is worth a 1000 climate model studies.
tallbloke (16:51:46) :
“Over the last 12 years GISS has a similar size trend to HAdcru UAH and RSS.”
What a complete different picture emerges if you extend your data to cover a period of 13.5 yrs (rather than starting at the anomalous El Nino year, as you did):
http://tinyurl.com/lvqjzj
GISS station data (http://data.giss.nasa.gov/gistemp/graphs/Fig.A.txt) are in good agreement with MSU.
But, after the extrapolation made by Hansen (http://data.giss.nasa.gov/gistemp/graphs/Fig.A4.txt) , we have a extra warming that is causing the divergence with MSU: (in 2008, by example, from +0.54ºC to +0.75ºC)
The problem isn´t the poor station coverage. The problem is in the extrapolation of the data to the zones without coverage.
In the ocean, GISS uses satellite data, being in agreement with MSU, of course.
Phil. (21:41:22) :
I have a question for you. What is the physical mechanism that causes CO2 to warm the planet?
“”” ohioholic (12:08:42) :
Phil. (21:41:22) :
I have a question for you. What is the physical mechanism that causes CO2 to warm the planet? “””
It’s really very simple.
CO2 is a rare trace gas in the atmosphere; about one in 2597 air molecules is CO2, so on average it is about 13.75 molecular layers in 3-d space between one CO2 molecule and another one; so they aren’t even aware of the other’s presence.
The earth’s surface which is mostly water, is many hundreds of times denser than the atmosphere, and the solid ground portion is on average 5-6 times denser than the water; and both of those materials emit something like 390 W/m^2 at the global mean temperature of about +15 deg C (288 K).
At that temperature, the emitted radiation has a specral peak emittance at around 10.1 microns wavelength. CO2 has a resonance vibrational absorption band at around 14.8-15 microns or so. At the surface density and temperature it is about 13.5 to 16.5 microns radiation that can be absorbed by the CO2 moelcule. The excited CO2 molecule collides with ordinary atmospheric gases of N2 and O2, nad rarely Ar, and the energy from the aborbed IR photons is redistributed and warms the atmospheric gases. The warm atmosphere in turn then radiates its own IR spectrum, which is generally at a longer wavelength, since the air temperature is cooler than the surface (Wien Displacement Law). The re-radiated energy goes in every direction, so only about half goes downwards towards the ground; the rest goes upwards towards escape to space. Because of the temperature and pressure gradients in the atmosphere, it is easier for the upward radiation to escape, than it is for the downward radiation to reach the ground. Multiple re-absorptions and re-emissions take place, with the downward path being more obstructed by more CO2 than the upward path which has less CO2.
So the portion of the downward IR re-emission that reaches the ground or ocean gets re-absorbed in the surface which replaces some of the lost energy, so the ground doesn’t cool as fast, which is akin to saying it stays warmer. In the case of the water surface, that surface IR absorption can cause prompt evaporation of water vapor into the atmosphere; which removes ahuge amount of additional thermal energy from the surface; around 545 calories per gram of water evaporated.
But CO2 is not like other gases; it is magic; and the sort of atmospheric warming that only CO2 can do, has the unique property of being able to wake up all the water vapor that is present in the atmosphere; about 25 water molecules for every CO2 molecule is typical. By themselves, water molecules which are also a green house gas, simply remain asleep and don’t do anything, until that magic moment when they are awakened by the CO2 molecule, and they immediately also start to absorb infra red radiation from the surface to add to the warming that the CO2 caused.
Now water vapor can absorb much more infrared energy than CO2 can; but only after being woken up by the CO2 molecule. That process is called “feedback”. So it is actually the water vapor that is the green house gas that causes global warming climate change; but only after it gets the go ahead from the wake up call from the CO2 molecule.
Not even Steven Hawking himslef has been able to explain why water vapor cannot warm the atmosphere by itself without the CO2 wake-up. Totally weird, that initial atmospheric warming by the ever present water molecules at around 25 times the abundance of CO2, is unable by itslef to warm the surface and do the whole job that it is able to do after being woken up.
That’s about the size of it; you could probably get yourself a Nobel Prize in Physics, if you can explain how CO2 wakes up water vapor and gets it to absorb Infrared, and warm up the atmosphere, and surface. Good luck
George
That’s about the size of it; you could probably get yourself a Nobel Prize in Physics, if you can explain how CO2 wakes up water vapor and gets it to absorb Infrared, and warm up the atmosphere, and surface. Good luck
Too late George, Clausius & Clapeyron did it over 150 years ago!