影响日本海夏季海洋热浪事件的主要大气环流型及其可能机理OA

In recent decades,the increasing frequency and intensity of marine heatwaves(MHWs)have posed a growing threat to marine ecosystems.The Japan/East Sea(JES),located in East Asia,has experienced frequent summer MHW events;however,the dominant atmospheric drivers and associated mechanisms remain incompletely understood.Using the NOAA Optimum Interpolation Sea Surface Temperature(OISST,version 2)dataset and ERA5 atmospheric reanalysis data for the period 1982-2023,this study identifies summer MHWs in the JES and investigates the primary atmospheric circulation patterns and physical mechanisms responsible for their development.The results indicate that summer MHWs in the JES are predominantly associated with a deep a-nomalous high-pressure system.This circulation pattern reduces total cloud cover,enhances downward shortwave radiation at the sea surface,and consequently leads to pronounced sea surface temperature warming.Treating all MHWs as a homogeneous category obscures the influence of atmospheric circulation;therefore,MHWs were fur-ther classified based on large-scale circulation characteristics.Using atmospheric teleconnection indices,the domi-nant circulation pattern influencing summer MHWs in the JES was identified.This pattern features a zonal"+-+"wave train over the Eurasian continent and a meridional"-+-"wave train over East Asia,with a positive geopo-tential height anomaly centered over the JES.Approximately 15 days prior to MHW onset,anomalously dry soil moisture conditions are observed in the Ural Mountains,while enhanced precipitation activity occurs over the o-cean east of the Philippines about six days before onset.These anomalies act as key precursors contributing to the development of the dominant circulation pattern.To verify this mechanism,idealized heat sources were imposed in a linear baroclinic model,with one heat source centered at the 1.0σ level over the Ural Mountains and another at the 0.45σ level over the ocean east of the Philippines.The model simulations successfully reproduce the formation of a positive potential height anomaly center over the JES,supporting the proposed physical mechanism.These findings provide important insights into the formation mechanisms of summer MHWs in the JES and offer valua-ble guidance for their monitoring and prediction.