Diagnostic Analysis Of The Impact Of The May Antarctic Oscillation On Summer Temperature In The Western Qinghai-Tibet Platea

Based on CRU global monthly temperature data,NCEP global monthly sea surface temperature data(ERSSTv5)and ERA5 reanalysis data from 1979 to 2020,this research analyzes the spatiotemporal variation characteristics of summer temperature and extreme high temperature events over the Tibet Plateau,and reveals the influence and possible mechanism of Antarctic Oscillation on summer temperature and extreme high temperature over the plateau through various statistical methods.The main conclusions are as follows:(1)Under the background of global warming,the summer temperature and extreme high temperature on the Tibet Plateau have significant spatiotemporal characteristics.The high correlation area of temperature related to the Antarctic Oscillation is located in the west of the plateau,while the high correlation area of extreme high temperature frequency is located in the middle and east of the plateau.(2)The AAO in summer affects the sea surface temperature anomaly(SSTA)in the middle and high latitudes of the Southern Indian Ocean when the AAO is weak in May,and the signal is stored in the SSTA through the Indian Ocean tripole mode.The thermal inertia of the ocean plays an important role in the process of prolonging the influence of the AAO.The influence of the AAO signal in May can last until the next summer through the Indian Ocean tripole mode of the Indian Ocean SSTA,and induce the wind anomaly over the Indian Ocean in the zonal and vertical direction.The precipitation anomaly between the tropical western Indian Ocean and the eastern Indian Ocean–Maritime Continent leads to a tropical dipole rainfall mode.As a response,abnormal anticyclone circulation and downward movement appear over the western TP,which is conducive to the high temperature there.(3)The Indian Ocean sea surface temperature triode index has a high correlation with the extreme high temperature of the plateau in summer.From the tropical Indian Ocean region to the plateau,there are significant meridional cyclone and anticyclone circulation anomaly waves,which transport the heat flux from the tropical Indian Ocean to the plateau through the circulation,and trigger the intense extreme high temperature frequency anomaly in the central and eastern part of the plateau.The vertical movement corresponding to the extreme high temperature anomaly triggered by IOT is shown as the downdraft in the 90°E～100°E region of the plateau,and the anticyclone divergence anomaly.