I_l is the observed radiance at wavelength l , T_sfc is the surface temperature, T_lis the transmittance and B_l(T) is the Planck function containing information on the atmospheric temperature. The term

is referred to as the weighting function. The intensity measured by a satellite radiometer due to the emission from a layer in the atmosphere at location z, is determined from the layer black body emission B_l(T)weighted by the factor W(z). The weighting function is of fundamental importance to vertical sounding the atmosphere from satellite observations. The weighting distribution depends on the strength and distribution of the absorbing gas.

Use this applet to explore the relationship between line-strength and gas concentration on the weighting function.

Radiation multiple choice

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