Satellite measurements of radiative forcing by greenhouse gases
W.F.J. Evans, North West Research Associates, Bellevue, WA
The radiative forcing of global warming can be measured by nadir viewing instruments on satellites. Spectral nadir measurements from several satellites can be processed to infer the radiative forcing (radiative trapping at the tropopause) from greenhouse gases. Ground based measurements of the surface radiative forcing from several major greenhouse gases have been conducted by spectral measurements of the greenhouse radiation from the sky with FTS instruments at 44N over a 10 year period. Examples of the two types of measurements for radiative forcing are shown; the surface measurement is an emission measurement and the nadir measurement is an absorption measurement. Comparisons of the two types of measurements at similar locations and seasons are presented. In general, the measurements are complementary and may be used for ground truthing of the satellite nadir flux measurements. The magnitudes agree within 25% and are opposite in sign. The role of water vapor as an interferent with greenhouse gas radiative forcing is clearly demonstrated.
Session 3, Detection and attribution of regional climate change
Tuesday, 16 January 2007, 8:30 AM-12:00 PM, 214B
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