南亚高压次季节尺度异常影响西太平洋副热带高压东西进退的机制研究

The western Pacific subtropical high (WPSH) during summertime has multi-scale spatial-temporal variations. Its variation of westward-eastward extension on 10-30-day sub-seasonal time-scale has attracted many literature, because of the close linkage with regional persistent heavy rainfall/persistent heat wave event, and being a precursor for 10-30 extending forecasting in China. The sub-seasonal variation of the South Asian high (SAH) is considered as one of the causes of the WPSH's westward-eastward extension on 10-30-day sub-seasonal time-scale. This project tends to investigate the joint effects and mechanisms of low frequency Rossby wave train propagation along the north side of the SAH, and positive feedback of diabatic heating over East Asia, to the WPSH's westward-eastward extension on 10-30-day sub-seasonal time-scale, during the sub-seasonal variation of the SAH. This project also analyses the connection between tropical and extropical through northern duct over the eastern part of the SAH. Based on the above connection, the dynamic process and mechanism of the SAH's influence on the convection activity over tropical western Pacific and then the variation of WPSH's location will be studied. The whole project attempts to reveal the mechanism of how the sub-seasonal variation of the SAH causing the WPSH's westward-eastward extension on 10-30-day sub-seasonal time-scale. It helps us to understanding the typical image of "going in opposite directions" of the WPSH and SAH.

夏季西太平洋副热带高压存在多时空尺度变异，其中副高10-30天次季节尺度的异常西伸东退，因与我国区域持续性强降水/持续性高温事件直接联系，并可为10-30天延伸期预报提供先兆信号而备受关注。南亚高压次季节尺度异常是引起10-30天副高位置异常东西变动的重要原因之一，本项目拟通过诊断分析和数值模拟方法，研究在南亚高压次季节变动中，南亚高压北侧的低频Rossby波列传播和东亚上空异常非绝热加热对环流的正反馈作用共同造成副高10-30天异常东西进退的过程和机理；分析南亚高压次季节变动中，南亚高压东部北风通道区对热带外与热带信号的连接作用；探讨南亚高压通过这种连接来影响热带西太平洋对流活动强弱振荡以及副高位置异常的动力学过程和机理。通过以上研究，揭示南亚高压次季节尺度异常影响西太副高10-30天尺度东西异常进退的内在机制，从动力学机理上深入理解两大环流系统“相向而行，相背而去”的经典配置图像。

夏季南亚高压和西太平洋副热带高压会出现两大环流系统“相向而行，相背而去”的经典配置图像，与我国天气气候异常事件紧密联系。本项目围绕这个问题展开研究。本项目分析了南亚高压与西太平洋副热带高压季节演变分析；进行了早夏期间南亚高压异常东伸与副高东西位置变动的动力学分析；揭示了南亚高压次季节尺度强度异常的大气内部动力学机制；南亚高压和副高次季节异常对持续性强降水和高温事件的影响；南亚高压次季节尺度东西振荡对我国长江流域降水及水汽输送的影响；长江中下游地区持续性强降水的年际和年代际变化及其相伴随的南亚高压与西太副高次季节配置对比。给出北太平洋洋中槽地区Rossby波破碎与副高位置异常的联系。以上研究有助于深入理解东亚大气环流和降水的次季节尺度异常特征和形成机理，并为10-30天延伸期预报提供先兆信号。发表了11篇相关论文，其中国际高水平期刊论文8篇。培养学生7人。