The brightness temperatures and their Jacobians with respect to atmospheric temperature and humidity at the microwave to millimeter wave spectral bands from 23 GHz to 424 GHz are simulated with the ECMWF IFS-137 profiles as inputs to the Advanced Radiative transfer Modeling System (ARMS). The information content of temperature and humidity is then calculated individually through the Shannon entropy which is contributed by a-priori background information and observations. For a typical set of measurement uncertainties, a high information content for atmospheric temperature is mainly obtained from V band near 50–70 GHz, whereas that for water vapor comes from G band near 183 GHz and Y1 band near 380 GHz. The channels within the G band have a large temperature information content mainly for lower and middle layers of troposphere and the Y1 band has a relatively large humidity information content for the entire troposphere. A large measurement uncertainty can significantly reduce the information content of each band. Thus, to make a best use of the data from each band, it is important to reduce the instrument calibration noise and increase the accuracy in forward radiative transfer simulation.

HIRAS II onboard in Fengyun-3E (FY-3E) early-morning-orbit meteorological satellite is the second generation hyperspectral infrared (IR) sounder of Chinese Meteorological Administration. HIRAS II has three consecutive spectral bands named long-wave (LW), medium-wave (MW) and short-wave (SW) band with 1671 more channels than its predecessor HIRAS I. Channel selection is implemented to get the optimal subset for application in numerical weather prediction (NWP) and to explore the contribution of each spectral band. The iterative channel selection method using information content (IC) is applied in temperature and water vapor channel selection based on temperature and humidity sampled profiles respectively. In total, 150 channels were chosen, consisting of 35 LW temperature channels, 65 MW temperature channels, and 50 MW water vapor channels. The temperature channel selection shows the selected channels in LW band present most information in upper troposphere, while the selected channels in MW band present most information in the mid and lower troposphere. It’s found that the humidity of atmosphere profile has large impact on the water vapor channel selection. As the increase of profile humidity, the maximum contribution layer of channel IC shift upward and the degrees of freedom for signal (DFS) profile become sharper and narrower, which results in the variation of channel selection.