Complementary vertical sensitivity unlocks full-column thermodynamics from combined ground and space microwave observations

Ground-based microwave radiometers (MWR) and satellite microwave sounders offer complementary vertical sensitivities to the atmosphere, enabling synergistic thermodynamic profiling. Capitalizing on China's robust national MWR network and advanced spaceborne microwave instruments, this study develops a retrieval framework that integrates ground-based MWR with Fengyun-3E (FY-3E) satellite observations. Information-content analysis reveals that the synergistic approach increases the degrees of freedom to 4.17 for temperature and 3.27 for specific humidity. These represent gains of approximately 109% and 81% over the MWR, and 26% and 29% over FY-3E, respectively. The synergy method also delivers a finer vertical resolution (∼2 km near the surface to ∼5 km at 300 hPa) and lower retrieval uncertainty than either isolated system. Independent validation against radiosondes confirms the superior performance of the synergistic retrievals, yielding the lowest root-mean-square errors for temperature (2.77 K), specific humidity (0.95 g kg−1), and relative humidity (14.08%). Importantly, these improvements directly enhance the accuracy of forecast indices. The synergistic configuration achieves optimal statistical performance for 9 out of 14 indices, including critical measures such as Convective Available Potential Energy (CAPE). These results quantitatively validate the unique value of merging ground and space-based microwave observations, for providing a more accurate and vertically consistent representation of the atmospheric thermodynamic state. This framework established offers a valuable pathway for enhancing future integrated observing systems, including the forthcoming Chinese geostationary microwave sounder mission.