Numerical Study on the Effects of Intraseasonal Oscillations for a Persistent Drought and Hot Event in South China Summer 2022

From 19 July 2022 to 31 August 2022, a rare persistent drought and heat event occurred in the middle of Yangtze River basin (MYRB). Normalized difference vegetation Index (NDVI) over 25% area decreased more than 0.05 compared with climatology, causing extremely agricultural disaster economic losses China. Previous studies have shown that occurrence compound events (CDHEs) MYRB was associated intra-seasonal oscillations (ISOs) from different latitudes. Nevertheless, what role ISOs at latitudes formation CDHE? To address this question, paper designed numerical simulation experiment partial lateral forcing investigate changes meteorological elements by removing signals on boundaries. We found wave series formed upper troposphere 200 hPa played significant CDHE northern part progress. It ISO component boundary caused mean temperature rise 2.4 °C aggravated 53.7% region. On other hand, anticyclone anomaly lower 800 had continuous impact southern eastern these two boundaries can increase average 1.93 intensify 49.7% area. In developing period CDHE, South Asian high Western North Pacific subtropical were coupled each jointly controlled MYRB, so positive geopotential height stayed above for long time, which conducive development local subsidence. The results will help better understand mechanism CDHEs assist meteorologists prevent forecast advance.