Microwave hyperspectral instruments represent one of the main atmospheric sounders of China’s next-generation Fengyun meteorological satellites. In order to better apply microwave hyperspectral observations in the fields of atmospheric parameter retrieval and data assimilation, this paper analyzes the sensitivity of trace gases to five selected bandwidth channels using a radiative transfer model based on the simulated data of microwave hyperspectral radiances at 50–60 GHz. This method uses information entropy and a weighting function to select channels and analyze the impact of this on the retrieval accuracy of atmospheric profiles before and after channel selection. The experimental results show that channel selection can reduce the number of channels by approximately 74.05% while maintaining a large amount of information content, and this retrieval effect is significantly better than that of MWTS-III. After channel selection, the 10 MHz, 30 MHz, and 50 MHz bandwidths have the best retrieval results in the stratosphere, whole atmosphere, and troposphere, respectively. When considering the number of channels, computational scale, and retrieval results comprehensively, the channel selection method is effective.

Microwave hyperspectral sounders are key instruments for next-generation meteorological satellites, designed to replace broadband sounders such as ATMS, MWTS, and MWHS. A major challenge in their design is determining the optimal channel bandwidth configuration to maximize the use of absorption spectra and enhance vertical atmospheric profiling. This study evaluates two variable-bandwidth strategies: (1) a generalized variable-bandwidth approach, which applies multiple fixed bandwidth combinations across different frequency bands, and (2) a dynamic bandwidth strategy, which differentiates channel bandwidths within the same frequency band for absorption peak and wing regions. The retrieval performance of various bandwidth configurations is analyzed for lower- and upper-atmospheric temperature and humidity observations. Results indicate that for upper-atmosphere temperature retrievals, the 60 GHz and 118 GHz bands achieve higher accuracy with a 10 MHz bandwidth. For lower-atmosphere temperature retrievals, where most information originates from the O₂ absorption line’s wing region, a wider bandwidth reduces observation costs while maintaining comparable accuracy. Water vapor retrievals, which primarily rely on the 118 GHz wing region and 183 GHz absorption lines, show minimal sensitivity to bandwidth configurations. A novel channel configuration method is proposed, integrating both absorption peak and wing regions into a single optimized scheme. Experimental results demonstrate that the 10+10+100 MHz (Peak) + 50+100+100 MHz (Wing) configuration achieves the best retrieval accuracy across different atmospheric layers, significantly improving both temperature and humidity profiling compared to existing broadband sounders. The advantages of using variable channel bandwidth hyperspectral microwave radiometers for joint retrieval of temperature and humidity profiles have been demonstrated from both theoretical analysis and quantitative retrieval (Optimal estimation method, OEM), providing theoretical support and technical guidance for the development of the next generation of spaceborne hyperspectral microwave radiometers.

This research investigates the potential of microwave sounders for a future international Venusian lower atmosphere exploration mission. Venusian microwave atmospheric radiative transfer (RT) calculations from a spaceborne perspective are performed with appropriate settings of the specific observation geometry and input atmospheric scenarios. An atmospheric profile perturbation analysis was undertaken to determine channel selection and corresponding retrieval accuracy. Meanwhile, a suitable configuration of microwave sounder is proposed based on the gas absorption characteristics, sensitivity and retrieval error analysis. The channel frequency selected includes 21 (2) channels of SO ₂ (H ₂ SO ₄ ) absorption lines and its sidebands, as well as 37 channels between 6-42 GHz. Due to the strong coupling between temperature, SO ₂ and H ₂ SO ₄ in lower atmosphere, a joint physical retrieval method (Optimal estimation method, OEM) is proposed. Under ideal model conditions, the RMSE of retrieved temperature profiles improves by 1.3 K to stay within 2 K for 0-65 km, while the maximum RMSEs for SO ₂ and H ₂ SO ₄ volume mixing ratios show improvements of at least 15% and 10%, reaching 30% and 25%, respectively. These results validate the proposed microwave sounder’s effectiveness for temperature and SO ₂ (H ₂ SO ₄ ) profiling up to 65 km (30 to 75 km for SO ₂ , 35 to 55 km for H ₂ SO ₄ ). However, increasing model error reduces retrieval accuracy, emphasizing the importance of model development for accurate joint observations of these parameters.