Atmospheric transmittance of amsu channels: A fast computation model

In this study, the atmospheric transmittance of individual NOAA AMSU microwave channels was computed into a 40-layer atmospheric line-by-line FASCODE radiation model. Long-term sounding data from 1956 to 1991 collected over the Taiwan area was used to construct a 40-layer standard atmospheric model for the island. The simulated transmittance was also used to establish a regression-based fast-algorithm model to compute the atmospheric transmittance of Taiwan and its surrounding areas for various purposes. Despite the fact that the lower atmospheric layers of channels 14-18 indicated larger errors, the overall results revealed that the absolute value difference between the AMSU pass band-averaged transmittances computed through FASCODE and the test model was smaller than 0.01 and 0.001 in the oxygen and water vapor channels, respectively.