Ground-Based Radiometric Sensing of Thermodynamic Variables in the Polar Regions

Here kf (h) accounts for the absorption coefficient of oxygen and water vapor. The water vapor absorption coefficient dominates the situation at or near the peak of the spectrum. This is also true for 183 GHz, a strong water vapor resonance line. If we look at the plot (Figure 5.1) of attenuation (dB), as reported by Smith (1982), for typical atmosphere, we see that at f = 22.235 GHz, kwater is larger than koxygen by a factor of 20 (ρ0 = 7.5 gm−3). In a dry climate, for (ρ0 = 1.0 gm−3), the ratio comes down to 3 only, and hence the total absorption coefficient is not as strongly dominated by water vapor.