Integrative Monsoon Frontal Rainfall Experiment (IMFRE-I): A Mid-Term Review

Abstract

The mei-yu season, typically occurring from mid-June to mid-July, on average, contributes to 32% of the annual precipitation over the Yangtze–Huai River Valley (YHRV) and represents one of the three heavy-rainfall periods in China. Here, we briefly review the large-scale background, synoptic pattern, moisture transport, and cloud and precipitation characteristics of the mei-yu frontal systems in the context of the ongoing Integrative Monsoon Frontal Rainfall Experiment (IMFRE) field campaign. Phase one of the campaign, IMFRE-I, was conducted from 10 June to 10 July 2018 in the middle reaches of the YHRV. Led by the Wuhan Institute of Heavy Rain (IHR) with primary support from the National Natural Science Foundation of China, IMFRE-I maximizes the use of our observational capacity enabled by a suite of ground-based and remote sensing instruments, most notably the IHR Mesoscale Heavy Rainfall Observing System (MHROS), including different wavelengths of radars, microwave radiometers, and disdrometers. The KA350 (Shanxi King-Air) aircraft participating in the campaign is equipped with Ka-band cloud radar and different probes. The comprehensive datasets from both the MHROS and aircraft instruments are combined with available satellite observations and model simulations to answer the three scientific questions of IMFRE-I. Some highlights from a previously published special issue are included in this review, and we also briefly introduce the IMFRE-II field campaign, conducted during June–July 2020, where the focus was on the spatiotemporal evolutions of the mei-yu frontal systems over the middle and lower reaches of the YHRV.

摘 要

梅雨季节一般发生在6月中旬至7月中旬,其间的降水量占长江流域年降水量的32%,是中国三大暴雨季节之一。在中国国家自然科学基金的主要支持下,中国气象局武汉暴雨研究所牵头,围绕三个科学问题,组织开展了长江中游梅雨锋降水联合科学试验(Integrative Monsoon Frontal Rainfall Experiment; IMFRE)。这三个科学问题包括:(1)如何更深入地了解梅雨锋上云和降水的微物理特性,层云和对流降水在不同阶段(发展、成熟、消散)中雨滴的形成和增长过程,水汽对MCS形成的影响?(2)驱动MCS和梅雨锋系统发展演变的动力和热力机制是什么,与云和降水的关系是怎样的?(3)如何定量评估WRF模式中云微物理方案的适用性,怎样获得适用于长江中游梅雨锋降水预报的云微物理参数化方案?本文首先简要回顾了梅雨锋系统的大尺度背景、天气形势、水汽输送、云和降水特征,其次介绍了于2018年6月10日至7月10日在长江中游开展的第一阶段试验情况(IMFRE-I)。参加试验的设备以中国气象局武汉暴雨研究所长江中游暴雨监测野外科学试验基地的地基观测设备为主,包括不同波长的双偏振雷达、微波辐射计和雨滴谱仪等。此外,来自于山西省人工防雹增雨办公室的空中国王KA350飞机也成功实现了八个架次的探测飞行。飞机装载了一整套云微物理探测仪器和Ka波段云雷达,获取了宝贵的探测数据。文中也简要介绍了试验期间获得的地基、空基和卫星综合观测数据集,以及已经取得的数据分析成果。本文也摘取了已在JGR特刊上发表文章中的一些亮点。最后,本文还简要介绍了在2020年6月至7月开展的第二阶段外场试验(IMFRE-II),即长江中下游梅雨锋暴雨联合科学试验。