The Influence Of Sea Temperature Background On The High Temperature Heat Wave In Eastern My Country In 2013

For the high temperature events that occurred in the eastern part of China in the summer of 2013,This article uses 160-station monthly temperature observation data from 1951 to 2016,and 753-station daily maximum temperature data from 1960 to2013 in China,and according to the previous definition,by analyzing the anomalies of the number of high-temperature days,the number of heat waves,the intensity,and the average summer temperature distribution to discuss the extremes of 2013high-temperature events.Using NCEP/NCAR monthly reanalysis data and the monthly SST data of NCEP COBE_SST,through EOF and composite analysis,the space-time characteristics and atmospheric circulation anomaly characteristics of these high-temperature events were analyzed,and their relationship with the anomalous distribution of sea surface temperature over the same period was discussed.Finally,a sea surface temperature sensitivity test using the atmospheric circulation model ECHAM5 was conducted to discuss the influence of the SST background on this high temperature event,aiming to reveal the climate characteristics of such high temperature events and the influence of the SST background.The main results are as follows:(1)In the summer of 2013,the number of high-temperature days in most parts of eastern China exceeded 50 days,and the number of dangerous high-temperature days exceeded 9 days.High-risk high-temperatures occurred,and the number of days exceeded 4 days.The number of high-temperature days,dangerous high-temperature days,and High-risk high-temperature days are the highest since1960.According to the area where the temperature anomaly is distributed,the middle and lower reaches of the Yangtze River(east of 105°E,26°-34°N)is the main influence area of the 2013 high temperature event.(2)There were five high-temperature processes in the high-temperature region in2013: June 16-20,July 1-5,July 7-14,July 23-August 18,and August 27-29 th,and the strongest process is July 23-August 18.The frequency of high-frequency heat waves,duration,and heat wave intensity in the high-temperature area increased significantly after 2000 and peaked in 2013.(3)The number of high temperature days and heat waves have a good correlation with the average summer temperature.Combined with the EOF,the 26-34°N and105-123°E regions are the key areas for such high temperature events.In the year of high temperature in key areas,the South Asian High appears obvious eastward and northward,and the high-level westerly jets enhance eastward extension,which is conducive to the northward and westward extension and long-term maintenance of the West Pacific Subtropical High.The Northern Hemisphere is an AO positive phase distribution: The polar regions are controlled by negative anomalies.The mid-high latitudes are controlled by positive anomalies,and the polar vortex is weakened in summer.The zonal circulation prevails in mid-latitudes,the airflow is relatively flat,and the east asia deep trough are shallow,which is not conducive to high-latitude cold air southward,and West Pacific subtropical higher and more west than the average climate state.At the lower levels,eastern China is controlled by anomalous circulation anomalies,and the East Asian summer monsoon and the equatorial easterly wind are significantly enhanced.The anomalous distributions of SSTA that may affect this high temperature event are: cold anomalies in the central and eastern equatorial Pacific,warm anomalies in the western Pacific,and the North Atlantic tripole distribution.(4)After declining trend and interdecadal signals,the West Pacific subtropical high in 2013 was weaker and the position was more northerly and westerly.Global SST forcing simulation results consistent with observations.Tropical SST forces make the area and intensity of the subtropical high slightly larger.West Pacific subtropical high can still be northerly and westward under weak conditions,mainly affected by the tropical sea temperature: The tropical SST anomaly distribution leads to an increase in the Walker circulation over the Pacific Ocean and the Indian Ocean,enhanced upward motion over the Western Pacific,followed by an increase in local Hadley circulation,leading the subtropical high to the northwest.