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| Total / opaque cloud vs Temperature
No slope on the opaque cloud but a definite dip when teperatures are between 16 and 22C
The following plots limit RH to 20 to 40%. Day refers to time that cloud can be measured Night to when cloud is not measured.
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| D/U LWIR vs Temperature (night values - 0-100% cloud)
Both upward and downward LWIR linear proportional to temperature
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| D/U LWIR vs Temperature (day values cloud 0-100%)
Very similar to night - slopes are a bit different.
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| D/U LWIR vs Temperature (day values but limiting cloud to 20 to 40%) (note change in humidity limits |
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| D/U LWIR vs Humidity Temp 22-24C cloud 40-50%
By constraining the temperature to a 2C band The temperature effects on IR are minimised whilst still returning a reasonable number of results. Note that the ULWIR falls with increasing cloud but the DLWIR rises by 100w/sq m
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| D/U LWIR vs Opaque Cloud cover temp 22-24C RH 35-40%
Temperature RH are constrained to minimise these effects. The DLWIR increases by approx 80 w/sqm
I think these last two plots conclusively prove relative humidity and cloud cover have a positive effect on the downward long wave ir (ir increases if cloud and/or RH increase)
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Re: Now how do you do this for CO2?
ReplyDeleteCan you do multiple MODTRAN runs for various levels of CO2 in your atmosphere, with your zenith angle set to either 0 or 180 degrees (I think the convention is zenith angle), using 8-12 microns (or whatever) for your band?
The varied CO2 levels correspond to the opaque cloud cover, the two zenith angles give downward and upward respectively (if I have correctly remembered the convention).
I am no expert on MODTRAN, but this seems like it would be a tractable modeling approach.
Unfortunately the data available from nrel does not give the dlwir ulwir for specific wavelengths - an overall w/sqm figure is all that is available.
ReplyDeleteAvailable data is shown here
http://www.nrel.gov/midc/srrl_bms/
There are UV bands but not LW IR
The idea with these plots was to remove "models" so hated by some. So it was just the measured values of interest.