Abstract:The return sounding observation is a new high-altitude observation technique developed by China. In addition to the observation of vertical profile in the ascending stage, at the same time, the atmospheric sounding in the period of floating and falling is added to this technique and the space-time densification of the sounding profile is realized automatically. In this paper, with the ERA5 reanalysis data as the “true value”, the return sounding simulation system is used to construct the return sounding simulation observation. Besides, Observing System Simulation Experiments (OSSEs) are conducted based on CMA-MESO regional model and 3D-Var assimilation system. The results of numerical experiments show that compared with the traditional single-rise sounding observation, the simulated sounding observation of the descending section of the return sounding can effectively improve the precipitation forecasting skills of CMA-MESO in the circumstances with national network, and the ETs scores for different precipitation grades can be improved by about 2%-5%. At the same time, the forecast of factor field (temperature, humidity and wind field) is improved, with improvement rate about 2%-5%. In addition, the analysis results of typical weather cases suggest that the increase of return sounding observations can improve the initial model deviation, thus more accurate simulation of precipitation distribution. Generally, the research results of this paper would provide a theoretical support for the future scientific layout and application of the return sounding.