摘要:西太平洋副热带高压（简称副高）活动规律及其变异的动力学机理问题一直是我国气象学家的重要课题。本文针对现有研究和预测中常用的高度场指数不能全面、准确刻画全球变暖背景下的副高演变特征的缺陷，利用全球大气环流三型分解模型中的流函数能够等价描述副高三维空间几何图像的优势，以500 hPa水平型环流流函数的零等值线为客观标准，给出了副高面积、强度、脊线及西伸脊点指数的新定义，并以2018年夏季副高的短期结构演变特征及其与我国东部地区降水之间的关系研究为例，验证了本文新定义副高指数的客观性与合理性。本文利用全球大气环流三型分解模型中的水平型环流流函数新定义的副高指数，不仅从形态上准确刻画了副高的大尺度涡旋环流特征，而且全球大气环流三型分解的动力学、热力学方程组为进一步利用新指数开展副高异常演变的机理研究提供新的理论工具。
关键词:全球大气环流的三型分解/
水平型环流/
流函数/
副高指数
Abstract:Formation and variation dynamics of western Pacific subtropical high (WPSH) have always been an important subject of interest for Chinese meteorologists. However, geopotential height field indexes commonly used in current studies and operational services cannot accurately describe the evolution characteristics of the subtropical high with a global warming background. It is known that the stream function of horizontal circulation defined by the three-pattern decomposition of global atmospheric circulation can equivalently describe the three-dimensional spatial geometric images of the subtropical high. Based on this information, this study proposes the use of the zero contour of the 500 hPa stream function of horizontal circulation as the objective standard to redefine the area, intensity, ridge line, and westward ridge point indexes of the subtropical high. The objectivity and rationality of the newly defined indexes of subtropical high are verified by taking short-term structural evolution characteristics of the subtropical high during summer in 2018 and its relationship with precipitation in eastern China. Results reveal accurate depiction of the large-scale eddy circulation characteristics of the subtropical high with the use of the newly defined indexes of based on the stream function of the horizontal circulation. Additionally, the dynamic and thermodynamic equations concerning the stream function of three-pattern decomposition of global atmospheric circulation provide a new theoretical tool for studying the mechanism of the evolution of the subtropical high anomaly by using the newly defined indexes.
Key words:Three-pattern decomposition of global atmospheric circulation/
Horizontal circulation/
Stream function/
Subtropical high index
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