Retrieval Analysis of Atmospheric Water Vapor for K-Band Ground-Based Hyperspectral Microwave Radiometer

Abstract

In this letter, we study the performance of a K-band ground-based hyperspectral microwave radiometer for the observation of atmospheric water vapor. First, a prototype of a K-band ground-based hyperspectral microwave radiometer for atmospheric sounding is proposed. This microwave radiometer is able to split the 18–26-GHz signal into 80 hyperspectral channels with identical bandwidth. Simulation studies, including the retrieval performance of water vapor and the vertical resolution of observation compared with the five-humidity-channel radiometer TP/WVP-3000 under the same conditions, are presented to assess the capability of the prototype. Simulation results show that the vertical resolution of this prototype is better than that of TP/WVP-3000 at a higher altitude, and the RMS water vapor error improves by about 10% at an altitude of 0–6 km. Moreover, by simulation, we analyze the impact of the radiometer channel number on the Shannon information gain and the RMS water vapor error of the hyperspectral microwave radiometer. At an altitude of 1.5–6 km, more information can be obtained by increasing the number of microwave spectrum channels. For water vapor profiling, the improvement of the retrieval RMS error from 10 to 800 channels at a higher altitude exceeds about 5%–10%.