The impact of IPOD on boreal midsummer extratropical cyclones accompanied by torrential rains in Central and Eastern China

Abstract

In recent years, extratropical cyclones accompanied by torrential rains (ETCTRs) have caused an increasing number of disasters in Central and Eastern China. However, our understanding of climatic mechanisms remains inadequate for operational prediction. By analyzing the atmospheric circulation of ETCTRs occurring in Central and Eastern China during the boreal midsummer period (July–August) from 1981 to 2020, this study found that these boreal midsummer ETCTRs may be influenced by the Indo-Pacific Warm Pool and North Pacific Ocean Dipole (IPOD). Diagnostic analysis and Linear Baroclinic Model experiments indicated that negative IPOD-type sea surface temperature anomalies can trigger positive geopotential height anomalies in the mid-upper troposphere over the subtropical region and negative geopotential height anomalies from the Western North Pacific to Northeastern and Northern China. This circulation pattern and moisture transport conditions are conducive to the formation of ETCTRs during boreal midsummer in Central and Eastern China and vice versa for the positive IPOD case. This study provides useful evidence for short-range climate prediction of boreal midsummer ETCTRs in Central and Eastern China.

Keywords

• extratropical cyclone (ETC)
• torrential rains
• Central and Eastern China
• midsummer
• IPOD