Climatic characteristics and main weather patterns of extreme precipitation in the middle Yangtze River valley

Abstract

Based on the daily precipitation data and ERA5 reanalysis data of 40 years from 1981 to 2018 in the middle Yangtze River Valley (MYRV), the climatic characteristics of extreme precipitation are analyzed using statistical methods. The multivariate empirical orthogonal functions and spectral clustering methods are used to classify and synthesize the extreme precipitation weather. The results show that: (1) The spatial distribution of the extreme precipitation threshold is uneven due to the regional topography. The spatial distribution of the average precipitation and frequency of extreme precipitation days is characterized by the north-south antiphase distribution. (2) According to the main influencing systems, the 215 regional extreme precipitation days in the MYRV in the past 40 years can be classified into three types: southwest vortex type, typhoon type, and cold trough shear line type. (3) The southwest vortex type of extreme precipitation occurs in the deep warm and humid airflow in front of the southwest vortex trough, but the typhoon type has better thermal dynamic conditions, and the cold and warm airflow convergence of the cold trough shear line type is more obvious. The rainfall area of three types of extreme precipitation is the result of the synergistic effect of the system. HIGHLIGHTS The climatic characteristics of extreme precipitation in the middle Yangtze River Valley (MYRV) in 40 years (1981–2020) are analyzed by statistical methods.; The multivariate empirical orthogonal functions and spectral clustering methods are used to classify the regional extreme precipitation days in the MYRV.; The synergistic relationship of the influence system of regional extreme precipitation days is summarized.;

Keywords

• extreme precipitation
• multivariate empirical orthogonal functions
• spectral clustering
• southwest vortex