| This paper starts from the two factors of ENSO and Sensible Heat(SH)in the Tibetan plateau(hereinafter referred to as plateau),based on the station observation data and the Interim reanalysis data,partial correlation,standardized multiple linear regression coefficient and synthetic analysis,besides,other statistical methods were used,according to the different abnormal phases of SH in the plateau and ENSO,they can be divided into 12 types(A total of three groups).The main physical processes and relative importance of SH and ENSO affecting the summer precipitation in south China(July and August)were studied,and their interactions were briefly analyzed.The main conclusions are as follows:(1)SH and ENSO had significant effects on the south China midsummer precipitation in spring respectively,that is,when the two were in their respective positive(negative)phases,the south China midsummer precipitation was generally less(more).Both plateau SH and ENSO have significant effects on high-level circulation,the major influence of plateau SH is 30 to 40 °N westerly wind anomaly,and ENSO have important effects on Walker circulation.However,from the perspective of low-level circulation,SH plateau makes south China appear closed anticyclonic anomalous circulation.Although ENSO anomaly corresponds to the strong western Pacific anticyclonic circulation,it is not closed over south China.Therefore,for low-level circulation,the relative contribution of plateau SH to summer precipitation in south China is more important.(2)Through on the plateau SH and ENSO respectively in their own separate role and positive(negative)phase comparison,the results indicatets that the El ni?o effect years alone,a sinking motion over the south China,and the whole layer over the equatorial regions as an upward movement,embodies the Hadley circulation,while the water vapor over the south China divergence,significantly extending subtropical high,cause less rainfall in south China.On the contrary,in the years when La ni?a acts alone,from the perspective of meridional circulation,the south China region shows a weak upward movement,leading to a negative precipitation anomaly in the(3)central and western regions of south China.It indicates that La ni?a annual anomaly has no independent effect on the midsummer precipitation in south China.Both the strong and weak plateau SH have an important effect on the summer precipitation in south China.There was an abnormal Hadley circulation over south China on the south side of the equator and the plateau.(4)The synergistic effect of SH in the plateau and ENSO reflects that when their symbols are consistent,they play a strengthening role in the midsummer precipitation in south China.When both ENSO and plateau SH are in the abnormal superposition of the normal phase,south China was a subsidence movement,and its ascending branches were located over the eastern part of the plateau and over the eastern Pacific Ocean respectively.However,the intensity of the anomalous upward movement over the plateau was significantly stronger than that over the eastern Pacific Ocean.When both ENSO and plateau SH are in the abnormal superposition of negative phase,the situation is opposite,and the precipitation in south China is obviously high.In the case of El ni?o with a strong negative phase disposition of SH in the plateau,it may show an offsetting effect.In contrast,when La ni?a and plateau SH are configured in a strong positive phase,only the negative effect of plateau SH in a strong positive phase is reflected,and the precipitation in south China in midsummer is negative anomaly in the whole region.(4)In winter,SST in Nino3 region has a certain influence on late plateau spring SH,but the influence is weak,indicating that the signals of ENSO in early winter are not directly stored in the spring plateau SH,and both of them play a modulation role in jointly influencing the summer precipitation in south China--ENSO and plateau spring SH play a leading role. |
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