国家重点基础研究发展计划 973 41175056国家重点基础研究发展计划（973）项目2015CB452804，国家自然科学基金项目41175056
1.Key Laboratory of Cloud-Precipitation Physics and Severe Storms, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029;2.Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing 210044;3.University of Chinese Academy of Sciences, Beijing 100049;4.Zhejiang Meteorological Observatory, Hangzhou 310017;5.Ningbo Haishu Meteorological Bureau, Ningbo, Zhejiang 315012;6.Ningbo Meteorological Service, Ningbo, Zhejiang 315012
To investigate possible impact of sea surface temperature (SST) change on surface rainfall process of tropical cyclone（TC） Soudelor over the ocean, sensitivity experiments are conducted using the Weather Research Forecasting (WRF) model and a 3D WRF-based precipitation equation based on the previous study of Wang et al. (2018). SST in the control experiment (CTL experiment, SST changes with time) is much different to SST in the sensitivity experiment (SNC experiment, SST remains constant). The results show that the difference in the simulated TC track over the ocean is small in the two experiments, but the simulated TC intensity in the SNC experiment is stronger than that in the CTL experiment. For the TC circulation, differences in the vertical velocity between the two experiments are basically positive in the troposphere (the SNC experiment yields stronger updrafts than the CTL). As the difference in SST increases, the vertical motion difference also becomes larger. Precipitation rate (PS )in the SNC experiment is larger than that in the CTL experiment, but the difference in PS between the two experiments increases non-linearly with the SST difference, which reflects the complexity of PS variation. QWVA (the three-dimensional moisture flux convergence or divergence rate) in the SNC experiment is basically larger than that in the CTL experiment (especially in the later period of the TC life cycle). This is because SST difference can affect vertical motion and cause QWVA difference, which in turn affects PS. During the study period of the two experiments, the atmosphere inside the TC continuously becomes drier (positive QWVL), and evaporation from the sea surface (positive QWVE) is significant.. There is little difference in QWVL between the two experiments. However, QWVE in the SNC experiment is generally stronger than that in the CTL experiment (especially in the middle and later stages of the TC life cycle). Temporal variations of the change rate of hydrometeor-related processes in the two experiments are complicated, but the magnitude of the maximum difference is comparable to that of QWVE. SST affects the growth of cloud hydrometeors content and deep convection, and thus differences in the variation of hydrometeors content gradually increased with SST difference between the two experiments. Among liquid-phase hydrometeors, large difference is found in raindrops, while differences in ice-phase hydrometeors, particularly large ice particles (snow and graupel), are even greater. In the SNC experiment, more graupel particles and raindrops are concentrated below the melting layer, which, concomitant with stronger updrafts, contribute to the occurrence and enhancement of Pracw(accretion of cloud water by rain) and Pgmlt（melting of graupels） and eventually enhance precipitation. Comparative analysis of regionally and temporally averaged macroscopic and microphysical processes related to the TC rainfall between the CTL and SNC experiments shows that the rainfall processes in the two experiments are qualitatively similar but quantitatively different. Compared with the CTL experiment, PS in the SNC experiment increased by 8.8%, which is mainly resulted from the difference in macroscopic and microscopic physical processes of precipitation between the two experiments. The different in QWVE isthe most obvious with different SST.