盛夏贝湖和鄂海阻高与东北冷涡配置主要流型异常特征研究

The characters of the flow patterns of main blocking high in mid-summer, in 500hpa height field over mid and high latitudes in the East Asia, is that the sustained blocking high over Lake Baikal and Okhotsk, referred to as the mid-blocking and the east-blocking, not only affect the circulation anomalies in the mid-latitudes directly, but also have an important impact on subtropical circulation anomalies. Different configurations among mid-blocking, east-blocking and Northeast Cold Vortex (NECV) result in different flow-fields in East Asia region, which is an important flow-fields of both high-impact weather and frequent event of climatic anomalies in our country, such as the persistent heavy rain over the northeast of China and the Yangtze River in mid-summer of 1998. This project will do some research on not only the more-objective detection methods, but also the climate and its anomalies, that response to configurations among mid-blocking, east-blocking and Northeast Cold Vortex (NECV), focusing on studying the anomalous characters of flow patterns of three main blocking high, namely dual blocking, dipole and "Ω". Using kinetics, thermodynamics diagnostic tests and numerical methods, focusing on how the spread of low-frequency disturbance affects the atmospheric blocking flow pattern, to reveal the interaction between the intraseasonal low-frequency waves and monthly-scale low-frequency waves, the transient waves and the local average flow, and its impact on configurations. This project is intended to reveal the main characters of the flow patterns of East Asian blocking high in mid-summer, and strive to study any possible mechanism of all configurations, to provide a scientific basis for early-signal capture of the flow patterns of northeast Asian blocking high in mid-summer.

盛夏500hPa东亚中高纬度地区主要阻塞流型特征为，贝加尔湖和鄂霍次克海阻塞高压持续（简称中阻和东阻），不仅直接影响中高纬度环流异常，还对副热带环流异常产生重要影响，中阻、东阻与东北冷涡不同配置呈现东亚不同的流型域，也是我国东部高影响天气与气候异常事件频发的重要环流型。例如，1998年盛夏东北与长江流域的持续暴雨灾害。以往对阻塞与冷涡分别研究较多，对其配置研究较少。本项将研究：盛夏东亚中阻和东阻与东北冷涡活动频次、相互间配置的气候和异常态，及其检测较为客观的方法；着重研究双阻、偶极子和“Ω”等三种主要阻塞流型异常特征。采用动力学、热力学诊断与数值试验等方法，侧重研究大气低频扰动的传播对阻塞流型的影响，揭示季内与月尺度低频波、瞬变波与局地平均流的相互作用对其配置的影响；本项旨在揭示盛夏东亚阻塞流型主要特征，力争对其各种配置的可能机理有所探索，为东北亚盛夏阻塞流型变化的前期信号捕捉提供科学基础

贝湖和鄂海阻高持续与冷涡不同配置是我国东部高影响天气与气候异常事件频发的重要环流型。本项拟给出科学、合理的系统识别方法；给出东亚阻高与冷涡主要流型配置标准、配置频次、持续时间，不同配置气候态和异常态等；揭示东亚双阻、偶极子和“Ω”流型异常特征及其可能的某些机理。研究表明:依据阻塞定义，研制自动识别为主和人工识别为辅相结合的客观识别方法。东亚阻高有利于冷涡维持和加强，给出冷涡持续活动及广义指数。利用NCEP/NCAR-I(II)和EC三套资料对比分析，揭示盛夏亚洲，尤其是贝湖和鄂海阻高、阻高与冷涡配置气候与异常态（三种资料差异小）。给出不同配置标准，贝湖与鄂海双阻流型分支和汇合点一般在80°E 、160°E（南北振幅达35°），冷涡特多年，以冷涡和阻高同时发生为主要流型，阻高先发生冷涡后发生流型为辅；冷涡特少年，以阻高先发生冷涡后发生为主要流型，“Ω”型很罕见。21世纪以来，冷涡活动略有增加，贝湖和鄂海阻高明显减小，乌山阻高活动明显增强。开展乌山-鄂海双阻流型气候动力学研究，乌山上游的低层波能量为双阻活动提供能量，既有利于下游低涡形成和发展，又为鄂海阻塞维持提供能量，该双阻活动在1977年前后发生一次显著突变，突变后双阻活动明显减少，突变前后能量频散由以向中低纬传播为主转为向高纬传播为主。春季到夏季赤道东太平洋（NINO3 区）SSTA呈El Niño位相是夏季东阻活跃最重要强迫源，大西洋海温整体上处于冷（暖）位相分布时，对应鄂海上空500hPa高度场为广阔负（正）距平区。应用浅水和准地转位涡守恒方程模拟阻塞形成过程，考虑大地形与大气基本流各种频谱相互作用时，基本流的y-方向高频波可使过山气流在x-方向有更低频响应，有利于阻高生成，亦助于其东南部冷涡形成，并在其西南部形成另一冷涡，构成“Ω”型阻塞，而y-方向低频波引发x-方向高频波致使阻高破碎。研究成果在短期气候预测中得到较好应用，为盛夏东北亚阻塞流型变化的前期信号捕捉提供科学基础。发表一级核心论文8篇（3篇SCI）。