Saturday, October 15, 2011

I am Still Getting Flack over the Value of Down Welling Radiation!

It seems that some people believe that there is no Down Welling Longwave Radiation (DWLR)or it is twice what it should be.

Here's the pooh. Yes, there is DWLR. Always has been. Always will be, if we have an atmosphere.

In the drawing by Kiehl and Trenberth, both the total flux for a black body at 288K and its calculate energy flux 390Wm-2, and the conductive plus latent heat fluxes are shown. Everything appears to balance. There is a difference between the radiant energy from the surface, absorbed by the atmosphere when compared to the NASA drawing. Approximately 24Wm-2 is the difference.

This is or at least should be common knowledge. My question was why?

If you turn off the sun, the conductive and latent fluxes do not stop as if by magic. The total outgoing energy will be equal to conductive (thermals in K&T's case) plus convective (latent in this case with a sensible component) and radiant. The total of all there will be 390Wm-2 initially.

390-24(conductive)-79 (convective)= radiant from the surface or 287 radiant. Got that?

Only the 287 is subject to the "Greenhouse" effect at the surface. The "greenhouse" effect cannot be greater than the energy effected. Yes, the total can be derived from the full 390 from the surface. 390 surface minus 240 top of the atmosphere is 160 Wm-2. The common value of the "greenhouse" effect is 155Wm-2, so it is a little different because the drawings are not exact in every way.

The 155Wm-2 is at the top of the atmosphere. 287-155=132 is the value at the surface. Notice the difference? Those two numbers give the ratio 155/132=1.17, 1.17*155=182. So the simplest estimate of what energy flux would produce 155Wm-2 at the TOA is 182Wm-2. No energy flow gets a free ride, the is always an energy loss in transmission. We live on a sphere and there is entropy.

The tropopause is a neat part of the atmosphere where the temperature is colder than any other place on or above the surface of Earth other than space. This is where the latent heat flux releases its heat eventually. That is up to 79 Wm-2 released directly to the tropopause. The absolute maximum energy of the "Greenhouse" effect could be 182+79=261Wm-2. But we know energy must be conserved, it would never be perfectly transfered to the tropopause. What may it be then? 240Wm-2, the "greenhouse" effect cannot manufacture energy, only retain energy, and that at a loss, entropy remember?

The "Greenhouse" effect due to a surface temperature averaging 288K cannot be greater than 240Wm-2 for our planet. If you add, 170Wm-2 solar absorbed by the surface to 390Wm-2 to 560Wm-2. Why would I use 560Wm-2 to determine the "greenhouse" effect of a planet at 288K emitting 390Wm-2 on average? I would not.

The "Greenhouse" effect is the radiative portion of the atmospheric effect, which just happens to be ~220Wm-2 measured at the surface, 155-160Wm-2 at the top of the atmosphere and 132-155 measured at the tropopause. Sorry life on Earth is not linear. The 321Wm-2 are the combination of conductive and radiant energy. With no "Greenhouse effect there would still be conduction. That's just the way it is.

So how much conduction? How much latent? How much non Greenhouse gas radiant? That's what I am working on, not some vision of perpetual motion caused by a silly cartoon with an incorrect number.

It appears that the models that generated that incorrect number are also generating an incorrect value of the "Greenhouse" effect. How much? About 10% +/- 8% more. That is all. A meager 10% that may mean a lot in the overall scheme of things.

Update: So why not use the 390 and 24? Or 390 and 79? Short answer, that's not the atmospheric effect. Look at it this way, 390W,-2 at the surface and 240Wm-2 at the TOA, is the atmopsheric effect. That's the TOA not the troposphere. That number asumes that the no GHG Earth was 255K or 33C cooler than now. That is assuming a lot. What would it be? By my calculations, 390-216=174Wm-2 or 235C at the surface and 255K at the TOA. The Earth would be 20 cooler because of latent cooling if there were no radiant flux interaction with the atmophere at all. But the actual temperature was 255K at the surface +/- 3 degrees, the possible error assuming 30% albedo which includes clouds and white ice. Would a frozen Earth with no atmosphere have clouds and snow? I don't think so. Latent energy cools the surface and warms the troposphere, conductive energy warms the surface and the atmosphere, radiant heat both cools the surface, warms the lower atmosphere and cools the upper troposphere. The net effect at the surface is more than 155Wm-2, but it is not 321Wm-2. Any value of change in flux that gives you the exact 33C includes all heat flux not just radiant absorption. You have to assume that conduction and latent heats do not exist to get than answer. Do they?

The fun part for me is that the silly Kimoto equation that I used, just to see if it may be valid, seems to be. If it is, it indicates some neat stuff. That the Earth environmental data collected for the global warming issue, may be accurate enough to provide some insight into relativistic Heat flow. One of accidental things that happens we you spend billions on research, you learn something new, something unexpected. Could it all be a bunch of crap? You betcha! But so far it just keeps showing promise. Fun stuff!

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