A new generation of microwave sounders, including the Advanced Microwave Sounder Unit (AMSU), on NOAA's polar-orbiting satellites has been providing global, continuous measurements of water vapor and many other atmospheric parameters for more than two decades. In the microwave region, water vapor, oxygen, nitrogen and ozone are active atmospheric gases. All of these gases are not considered in radiation transfer models for calculating radiation in satellite microwave radiometers including AMSU.
The aim of this article is to investigate the effect of ozone absorption lines on the brightness temperature of AMSU radiometer. For this purpose, first, using the Atmospheric Radiation Transfer Simulator (ARTS) model, the absorption spectrum of ozone was simulated in the range of AMSU frequencies, and then the location of these channels was placed on the absorption spectrum of ozone. Some AMSU channels are located near the peaks of ozone absorption lines, which can affect the brightness temperature of these channels. For quantitative analysis, the lighting temperature of all 20 AMSU channels, without including ozone and including with ozone was simulated and then the brightness temperature differences (∆TB) was calculated in both cases. The ∆TB values for all channels were negative, that is, the presence of ozone reduces the brightness temperature. The results also showed that ozone has the greatest effect on channels 5, 1, and 8 of AMSU-A and channels 18, 17, and 20 of AMSU-B, respectively. The highest value of ∆TB was obtained for channel 18, with an approximate value of 0.6 degrees Kelvin.