Study On The Thermal Effect Of Precipitation In The Qinghai-Tibet Plateau

The Tibetan Plateau?TP?is the highest plateau in the world,the weather and climate characteristics of it are unique,and it has important implications for the Asia and even globe climate change.Based on the site data of the TP and the reanalysis datasetes from the 1980 to 2016,the changes of the precipitation and the heat source of the atmosphere are studied by using multiple analysis method,such as synthetic analysis,correlation analysis,EOF analysis?Empirical Orthogonal Function?and SVD analysis?Singular Value Decomposition?,etc.And the relationship between precipitation and heat source is also discussed in it.The result of the analysis shows that in the past few years,the annual average precipitation of the southeast of the plateau is more than those in the northwest.The increasing of precipitation in annual change is not significant.In the seasonal changes,summer has the most precipitation while winter has the least,and every year there was a single peak change in the precipitation,July was the peak,and December was the minimum.Over the years,the average<Q₁>value of the plateau is mainly distributed in the northwest of the plateau in the form of atmospheric heat source,and the Qaidam Basin,the Yarlun-tzanpo River Valley and the Nujiang Basin are the main heat sink center.The heating effect and the cooling effect of the Tibetan Plateau has obvious seasonal conversion,the heating effect mainly appears in April to September,and the cooling effect is mainly in January to March,October to December.Sensible heat and condensation latent heat mainly take the heating effect to the atmosphere while the cooling effect of the atmosphere is mainly caused by the net radiation of the atmospheric column.The condensation latent heat of the heat source period?April to September?contributes most to the atmospheric heat source during the same period and the whole year.But for the effect of heat source,the sensible heat is still very important,this mainly reflected in the interannual change.There is a obvious turn in the change trend of<Q₁>value of the plateau in the whole year and during the heat sink period in 2003.The sensible heat's annual and seasonal changes of the year also had obvious trend change around 2013.During this period,I have prepared the calculated plateau sensible heat with the reanalysis data ERA-Interim,NCEP1 and NCEP2;the overall characteristics have good consistency,the site data is still strongly embodied in the characteristic of the region.The strong precipitation years and weak precipitation years are selected from the37 years,with the negative correlation form of precipitation anomalies in the regional distribution.Through the synthesis analysis,I found that the abnormal distribution characteristics of the<Q₁>value is similar to that of precipitation,in the year that has the most precipitation,the<Q₁>value shows the characteristic of abnormal more in the south and southeast of the plateau;in the year that has the least precipitation,the<Q₁>value shows the characteristic of abnormal less in the south and southeast of the plateau.In the month-to-month changes,the<Q₁>value is basically consistent with the abnormal change of precipitation;the difference of the<Q₁>value and precipitation between the strong year and weak year is large in April to October,particular in July,which indicates that the change of precipitation has a great influence on the atmospheric heat source.Precipitation not only promotes the atmospheric heat source,but also inhibits it,which mainly reflect in its influence on the sensible heat.The relationship between the effect of the sensible heat to abnormal precipitation and the precipitation is negative,in the year that has the most precipitation,the sensible heat in most parts of the central and eastern of the plateau shows the characteristic of abnormal less,while in the year that has the least precipitation,the sensible heat anomaly shows the form of positive in south and negative in north,and there is much more sensible heat in the south.This may be related to the influence of precipitation in pluvial period on the surface temperature,which can affect the temperature difference of the earth,and thus the cause negative correlation relationship to the sensible heat.But the sensible heat in pluvial period is mainly influenced by the wind speed,and the sensible heat in rainless period is affected by the temperature difference of the earth.Therefore,in pluvial period,precipitation influence the sensible heat on the surface mainly through affecting the temperature difference of the earth,but it is not the main factor that affecting the sensible heat.There is a significant negative correlation between sensible heat and monthly precipitation,and it is found through SVD analysis that the sensible heat of April is indicative to the forecast of precipitation in May and July.There is a good correlation between in the sensible heat of the plateau in spring and the precipitation in summer,and there is a prominent correspondence in local area.