摘要:利用WRF模式对2015年热带气旋（TC）"苏迪罗"发展演变过程开展高分辨率数值模拟，模式较好地再现了"苏迪罗"路径、强度、高低空环流、云系演变和降水分布等。应用三维地面降水诊断方程对"苏迪罗"海上活动时段的降水物理过程模拟诊断指出，QWVA（三维水汽通量辐合辐散率）对TC环流区域内降水相关的水汽相关过程变率（QWV）变化起主导作用，但环流区域内QWVL（垂直积分负的水汽局地变化率）和QWVE（海面蒸发率）亦有重要贡献（尤其是后者），尽管QWVE贡献明显小于QWVA，但由环流区域外辐合来的水汽也可能主要源于区域外不同海域的海面蒸发，海面蒸发的总体贡献应更大。海上活动时段云相关过程变率（QCM）特征及变化与QWV相比更为复杂，环流区域内的QCLL（负的液相水凝物局地变率）基本维持正值（液相水凝物持续减少），其消耗主要用于向冰相水凝物转化和地面降水，以及向区域外的三维通量辐散，6日04时之前，环流区域内QCIL（负的冰相水凝物局地变率）的变化主要归因于微物理转化及地面降水，而6日04时之后，来自环流区域外的通量辐合也有一定作用；降水强度逐渐增强时期，水凝物含量的短暂增长（负值QCLL和QCIL）主要归因于明显增强和垂直扩展的上升运动，伴随上升运动增强，水凝物含量明显增加，霰融化（Pgmlt）和雨滴碰并云滴（Pracw）是造成雨滴含量增加的主要微物理过程。"苏迪罗"环流内区域和时间平均的降水效率高达96%，其中QWVA是主要贡献项，而QWVE和QWVL亦有重要贡献，这与TC所处海洋下垫面有关，海上活动时段，充足的降水源和较小的降水汇共同造成此时段的高降水效率，雨滴生成主要微物理来源中，Pgmlt约占Pracw的72%，体现出海上活动时段TC环流内旺盛的深对流活动特征。
关键词:降水物理过程/
热带气旋/
海上活动时段/
三维地面降水诊断方程
Abstract:The development and evolution of tropical cyclone (TC) "Soudelor" (2015) was simulated using the Weather Research and Forecasting model (WRF). The simulation well reproduced the path, intensity, circulation, cloud system evolution and rainfall of "Soudelor". The three-dimensional surface rainfall equation was applied to quantitatively diagnose and analyze the precipitation process of "Soudelor" when it moved over the ocean. The results show that QWVA (the three-dimensional moisture flux convergence or divergence rate) played a major role in the variation of the rate of change for moisture-related processes (QWV), which was related to precipitation inside the TC circulation. But QWVL (vertically integrated negative local change rate of water vapor) and QWVE (surface evaporation rate) also made important contributions (especially the latter). Although the contribution of QWVE was significantly less than that of QWVA, water vapor that converged outside the circulation might be mainly come from the evaporation of sea water in different areas outside. Thereby, the overall contribution of sea surface evaporation should be great. The characteristics and variations of QCM (the rate of change for cloud-related processes) were more complicated than that of QWV, and QCLL (vertically integrated negative local change rates of liquid-phase hydrometeors) inside the circulation maintained positive (liquid-phase hydrometeors continuously decreased) throughout the incipient stage. Liquid-phase hydrometeors were largely consumed by converting into ice-phase hydrometeors and feeding the surface rainfall as well as by three-dimensional flux divergence. QCIL (vertically integrated negative local change rates of ice-phase hydrometeors) mainly stemmed from microphysical processes and surface precipitation before 0400 UTC 6. The flux convergence from the outside circulation also had certain effects after 0400 UTC 6. With increased surface rain rate, the transient growth of cloud hydrometeors (negative QCLL and QCIL) were mainly attributed to the ascending motion that enhanced markedly and expanded vertically. Cloud hydrometeors increased obviously with the sharply enhanced upward motion. Melting of graupels (Pgmlt) and accretion of cloud water by rain (Pracw) were two main sources of raindrops. Regionally and temporally averaged precipitation efficiency inside the TC circulation was as high as 96%. QWVA was the main contribution term, while QWVL and QWVE also made important contributions, which was related to the underlying ocean surface where the TC was located. When the TC moved over the sea, both the abundant source and the small sink for surface rainfall led to the high precipitation efficiency. As the main source of raindrops, Pgmlt accounted for 72% of Pracw, which reflected the characteristic of active deep convection inside the TC circulation during this period.
Key words:Rainfall process/
Tropical cyclone/
Activity period over the sea/
Three-dimensional WRF-based precipitation equation
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