Surface Sensible Heat Anomalies Over The Tibetan Plateau And Northwestern China And Their Synergistic Effects On The Northern Edge Of The Subtropical Summer Monsoon

The basic climatic characteristics of the northern edge of the subtropical summer monsoon are analyzed according to the standard of process rain,and the spatial and temporal distribution characteristics of the summer monsoon precipitation are analyzed.Using satellite data and station data,the daily sensible heat flux data from 1982-2015 in Northwest China and Qinghai-Tibet Plateau were obtained and compared.Using the conventional meteorological statistics method,the spatial distribution and temporal evolution characteristics of the surface sensible heat days in the plateau and northwest are studied,and the relationship between the thermal effects of the two regions is analyzed.Then,the influence of the sensible heat in the early spring of Northwest China on the precipitation in the mid-season of the monsoon is analyzed,the synergistic effects of plateau and northwest sensible heat on the northern edge of the subtropical summer monsoon are discussed.The main conclusions are:(1)The interannual variation of the position of the northern margin of the subtropical summer monsoon in East Asia has a tendency to move southward,and the time to reach the northern edge is advanced.The precipitation in the edge of the monsoon from July to August is mainly concentrated in the south of the northwestern part of the country.The precipitation decreases from the southeast to the northwest,and the interdecadal variation generally decreases,the most significant reductions are in southern Gansu and northern Ningxia,with linear reductions of more than 40%/10 a.(2)The plateau has a bimodal change during the year,and the whole year is positive.The spring is the hottest,followed by the summer,the sensible heat in the northwestern region is unimodal,with negative values in the first 6 and the 60 th,showing a weaker cold source.The warming of the plateau in the late winter and early spring is generally earlier than in the northwest.The time of sensible heat loss in the plateau is mainly concentrated in early September,and the time when the northwest region begins to weaken is mainly concentrated in late September.In the plateau and northwestern regions,the sensation of sensible heat in the spring is later(earlier),and the time of sensible heat loss in August and September is also later(earlier).This phenomenon is more obvious in the plateau.(3)When the spring plateau is stronger than the whole,the sensible heat in spring and summer in the central and western regions is obviously enhanced,and the summer is more significant.When the sensible heat in the spring plateau is weaker(stronger)in the east and stronger(weaker)in the west,the sensible heat is weaker(stronger)in the Tarim Basin and its northeastern regions,southwestern Gansu,and Ningxia Plain.When the sensible heat enhancement in the eastern part of the plateau is earlier(later),the southwestern part of the Qaidam Basin is later(earlier),and the sensible heat enhancement time in most parts of the northwest is earlier(later).(4)When the spring heat in the southern part of the plateau is abnormally weaker(stronger),the north is stronger(weaker),the sensible heat in the central and western regions is weaker(stronger),the time that the subtropical summer monsoon reaches the northern edge is abnormally earlier(later).The onset time and retreat time of the monsoon are greatly affected by the sensible heat of the plateau,the earlier the plateau sensible heat enhancement time in the current period,the later the monsoon onset.