Do Global Energy budgets make sense. ???
04-09-2010, 07:31 AM
RE: Do Global Energy budgets make sense. ???
Elsewhere Dick Kahle has posted the below response which raises and explains
some other very basic known problems with the K/T Global Energy flow budgets.
He has very kindly allowed me to post it here as well, which I am very grateful to him for.
I think it only fair to state that Dick Kahle is a radiation / energy specialist,
not a heat flow specialist so some of what he describes is from
a very different point of view than mine and others expressed here so far.
Discussions here and elsewhere continue regarding 1) the "radiation is all positive" question, and,
2) the K/T budgets are energy / radiation budgets so heat flow descriptions and problems do not apply issue.
The reader will have to make their own mind up on these issues, but in the end there are
several areas of concern regarding the K/T budgets almost all would, and do, agree upon.
In my mind at least "the jury" is still out on both the above basic issues.
However in the below Dick Kahle does raise and clearly explain
some problems already covered and more problems not mentioned so far.
He also clearly describes other known limitations to the K/T budgets that have not been mentioned to date.
" The K/T budget is representative only for a general explanation.
It can't be used as a model or a proof of anything.
You can make some average calculations about changes in these averages but
there is not any way to know the changes will represent the real world.
As a static average it can not reflect the condition at any given location and
has even less ability to describe changes in what is a dynamic process.
When you say relatively, if you mean radiation netted on an energy basis,
then we are in agreement on that point.
The w/m2 in the K/T budget are per second. That is common practice.
It's an average for a year.
As such it has all the limits and dangers of being misused because it is an average.
The w/m2 is intended to represent the energy in the radiation, conduction, evapotranspiration, and convection.
As you say it is not frequency specific which is why it is only representative of
a static average based on certain assumptions about the radiation.
If the radiation from the sun changes and it changes more in the UV range than the visible range,
the K/T has zero ability to deal with this.
The temperatures associated with the radiation would have to include knowledge of the emissivity of the emitting object.
Thus, it can't really tell us the temperature of the surface or the clouds or the clear sky unless
we know the emissivity. If it assumes an emissivity of 1.0, that is another simplification that limits it value.
There are some other limits of K/T. It assumes that there is energy balance at the tropopause.
However, the stratosphere varies in composition of greenhouse gases including water vapor.
This is not even in the K/T budget as an average.
It assumes the stratosphere rebalances radiatively so we only have changes below the tropopause.
The assumption that the solar radiation reaching the top of the tropopause
is dependent only on the sun is not correct.
The K/T budget does not provide a way to reflect changes in atmospheric circulation, particularly horizontally.
It is not intended to do that, but it remains a limit.
The K/T budget does not include allowance for the mass of the atmosphere,
water vapor in the atmosphere, the shape of the atmosphere,
or account for the specific heat of water, or land, except as average assumptions.
For example, if the vertical temperature profile of the ocean changes due to winds, or ocean currents, or a combination thereof,
the convection, evaporation and radiation from the ocean surface will change
without being caused by changes in the other parameters in the K/T budget.
Obviously, once temperature of the ocean surface changes, then the rest of the parameters,
except the solar input, will change where that effect is observed.
Even in the GCM's, the understanding of ocean circulation seems to be significantly limited
because they can't produce such cycles as the ENSO, PDO, AO, etc, as they occur in nature.
The K/T budget does not allow for any external inputs except average total solar irradiance.
It does not provide a means to represent potential effects of
cosmic rays, the solar wind, the suns magenetic field, coronal mass ejections and
the gravitational impact of the moon, sun or other planets on the earth, particularly the oceans.
So duration of flow is per second averaged over a year.
Temperature would have to be calculated using emissivity values.
Those are not given, although the earth's surface will be very close to 1.0.
The clouds radiate more than the solar input because energy is stored in the atmosphere
due to the absorption of all of the greenhouse gases, water being the most important,
plus black carbon and convection (conduction) and evapotranspiration.
As the atmosphere warms it allows the surface to warm to an average temperature higher
than if there was not energy absorbed by the atmosphere.
Although clouds or other parts of the atmosphere may emit radiation at
an average higher than the incident solar radiation,
the surface is emitting radiation at a higher energy level than the clouds and atmosphere (on average).
So I can look at the K/T budget as a static representation of
an annual average of the energy budget from the earth's surface upward.
It's use beyond that is severely limited and it does not provide by any means
a full understanding or representation of all climate processes.
Dick Kahle "
The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.
H. L. Mencken.
The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
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RE: Do Global Energy budgets make sense. ??? - Derek - 04-09-2010 07:31 AM
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