本計畫主要針對侵台颱風與梅雨期之中尺度對流系統降水雲雨物理以及伴隨之大氣中尺度環境，特別是低層噴流與大氣邊界層之熱動力結構發展與演變，以及水氣之傳送等進行觀測實驗分析與模式模擬研究。研究之重點將著重於探討侵台颱風或梅雨鋒經過台灣前後，低層噴流、海陸風與山谷風等局部氣流以及大氣邊界層與地形之交互作用對中尺度對流系統之生成與發展。結合剖風儀雷達、雙偏極化雷達與雨滴譜儀觀測網觀測分析雨滴粒徑等降雨雲物理之變化以及劇烈地形降水之中尺度環境條件與物理過程之影響。針對豪大雨個案利用高解析之WRF模式進行邊界層參數化、微物理參數化與地形效應之敏感度模擬，並利用觀測實驗之觀測資料進行模式之驗證，亦結合觀測分析與模擬實驗對造成台灣劇烈降雨之相關之物理過程做詳細深入的探討。 我們將深入探討梅雨季可能造成台灣劇烈降雨的三種低層噴流[綜觀系統低層噴流(synoptic-system-related low-level jet/SLLJ)、地形急流 (barrier jet)、海洋邊界層噴流(marine boundary layer jet/MBLJ)]與地形的交互作用和與梅雨系統的關係，還有其對於梅雨鋒面系統伴隨的中尺度對流系統的發展、結構演變與降水機制的影響。也會從東沙島和台灣本島的探空和剖風儀觀測來比較TAHOPE/PRECIP2020實驗的颱風與梅雨時期的西南氣流/低層噴流的大氣邊界層之熱動力結構發展與演變，並比較兩者的水汽傳送到台灣的特性，還有深入分析颱風引進的西南氣流與劇烈的地形降雨的特徵。不同天氣系統與中尺度環流下雨滴粒徑分布與變化以及其他伴隨之降雨雲雨物理過程的特徵也將深入探討。 ;This project mainly focuses on the cloud and precipitation microphysics processes of the mesoscale convective systems (MCSs) associated with the invaded typhoons and Mei-Yu systems, and the mesoscale atmospheric environment (especially the evolution of low-level jet, thermal and dynamical atmospheric boundary layer structures and the moisture transport) using field campaign observations and numerical simulations. The research will emphasis on the low-level jets, land-sea breezes, mountain-valley breezes, local circulations, atmospheric boundary layer, and terrain effects on the initiation and development of MCSs during a typhoon or Mei-Yu front passes over Taiwan. The evolution of raindrop size distributions and precipitating cloud microphysics, as well as mesoscale conditions and dynamical/physical mechanisms associated with heavy orographic precipitation will be investigated. For heavy rainfall cases, sensitivity tests of the planetary boundary layer parameterization, microphysics parameterization and terrain effects will be constructed using high-resolution WRF model. In addition, field campaign observations will be used to verify model simulation results. The above related physical processes for the development of heavy rainfall over Taiwan will be discussed using a combination of observations and numerical simulations. We will investigate three kinds of low-level jets that could possible contribute to heavy rainfall over Taiwan (synoptic-system-related low-level jet/SLLJ, barrier jet, and marine boundary layer jet/MBLJ): (1) the interaction between these low-level jets and terrain, (2) the relationship between them and the Mei-Yu system, and (3) their impacts on the development and structure evolution of mesoscale convective systems associated with the Mei-Yu system and physical mechanisms of precipitation. In addition, we will compare the development and evolution of thermal and dynamical atmospheric boundary layer structures and the moisture transport characteristics within the southwesterly monsoon flow/low-level jets during TAHOPE/PRECIP2020 (Typhoon and Mei-Yu periods) from soundings and wind profiler observations on Dongsha and Taiwan Islands. We will also analyze the characteristics of the heavy orographic precipitation resulting from the southwesterly flow associated with Typhoon.
