http://www.eia.doe.gov/cneaf/alternate/page/environment/chap2.html
Scientists used to believe that Venus fell victim to the greenhouse effect because 96 percent of its atmosphere is carbon dioxide, with nitrogen accounting for almost all the remainder [26]. It is now generally agreed within the planetary atmospheres community that carbon dioxide alone would lead to an average temperature of less than 25oC. The primary reason that Venus is warmer than this is the presence of sulfuric acid cloud cover over the entire planet, extending from about 50 kilometers to 70 kilometers from the surface.
Venus blackbody temperature is 231.7K [ http://nssdc.gsfc.nasa.gov/planetary/factsheet/venusfact.html ]
By the Boltzman black body relation:
Blackbody flux (E231) without atmosphere & clouds effects = 5.67*10-8(231.7oK)4 = 163.41 w/m2
Venus: Surface pressure = 92 bars, @231.7K, CO2 concentration = 0.962;
Earth Surface pressure = 1 bar, @231.7K, @ CO2 concentration = 380ppmv, Tropopause IR flux = 139.79 w/m2
according to 1976 standard atmosphere MODTRAN Radiation Calc (with 0 GHGs other than CO2)
@ CO2 concentration = 380ppmv & 231K temperature condition, = 139.79 w/m2
@ CO2 concentration = 000ppmv & 231K temperature condition, = 152.23 w/m2Yielding a total absorption of (152.23-139.79) = 12.44 w/m2 flux absorbed by 380 ppmv CO2 @ 231.7K temp.
The total concentration of CO2 on Venus with respect to 380ppmv level found on Earth is
92*0.962/(1*0.000380) = 230,373.68 times earth CO2.
Therefore Venus total CO2 IR flux absorption @ Venus 231K blackbody condition with 92 bar 0.962 CO2 is
(5.35*ln(230,376.68) + 12.44) = 78.5 w/m2.
The resulting Venus temperature due to CO2 absorption alone @ Venus blackbody conditions becomes:
[(163.41 + 78.5)/(5.67*10-8)]0.25 = 255.57K
Thus the maximum change in temperature on Venus for its current level of CO2 & pressure is
(255.57-231.7) = 23.87K (i.e. 23.9oC)
Which I would say demonstrates the EIA statement:
http://www.eia.doe.gov/cneaf/alternate/page/environment/chap2.html
Scientists used to believe that Venus fell victim to the greenhouse effect because 96 percent of its atmosphere is carbon dioxide, with nitrogen accounting for almost all the remainder [26]. It is now generally agreed within the planetary atmospheres community that carbon dioxide alone would lead to an average temperature of less than 25oC. The primary reason that Venus is warmer than this is the presence of sulfuric acid cloud cover over the entire planet, extending from about 50 kilometers to 70 kilometers from the surface.
Very well.
First its great you able to reverse engineer their math.
And I'm nowhere near ready for a full response. I'm a bit awed at the work you put into this and I don't want a hasty response.
But couple of questions, if you don't mind.
1. I didn't see any glaring errors in your Venus absorbtion caluculation of ~80w/m^2.. Have you seen the Pioneer Venus probe data that showed about 200 w/m^2 was getting through the cloud shroud with about 20 w/m^2 getting to the surface? That would seem to imply we are missing 100 w/m^2 somewhere.
2. Have you seen either the ~80w/m^2 absorption number or the 25 degree contribution to warming from CO2 anywhere reputable other than that 1994 paper or its 2002 electronic version?