Comparison of surface radiative forcing with tropopause radiative forcing by 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. Spectral nadir measurements from several satellites can be processed to measure the radiative forcing (radiative trapping) at the tropopause from greenhouse gases. 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 presnted. 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 vapour as an interferent with grennhouse gas a radiative forcing is clearly demonstrated.