The sensitivity analysis of microwave radiometer's brightness temperature and geophysical parameters

In 2000, Frank Wentz and Thomas Meissner described a model function for the microwave radiometer's brightness temperature of the ocean and intervening atmosphere. The oceanic and atmospheric parameters are the sea surface temperature, the near-surface wind speed, the columnar water vapor and the columnar cloud liquid water. We analyzed the sensitivity between the geophysical parameters and the microwave radiometer's brightness temperature with the model function. First, we find that the sensitive bands of the sea surface temperature are 6.93 GHz v-pol and 10.65 GHz v-pol; the sensitive bands of the near-surface wind speed are 6.93 GHz h-pol, 10.65 GHz h-pol, 18.7 GHz h-pol, 23.8 GHz h-pol and 36.5 GHz h-pol; the sensitive bands of the columnar water vapor are 18.7 GHz v-pol, 18.7 GHz h-pol, 23.8 GHz v-pol, 23.8 GHz h-pol, 36.5 GHz v-pol and 36.5 GHz h-pol; the sensitive bands of the columnar cloud liquid water are 36.5 GHz v-pol and 36.5 GHz h-pol. Second, we find that the brightness temperature is sensitive to incidence angle variations. One-degree error in specifying incidence angle produces a 2.5 K error in brightness temperature. The 2.5 K errors in brightness temperature produce 5 K errors in sea surface temperature and 4.5 m/s error in near-surface wind speed. Third, we find that brightness temperature is not sensitive to the sea surface salinity in the 6 to 37 GHz band.