The Characteristics Of Dry And Wet Variation In Indochina And Its Attribution Analysis

This paper uses the reanalysis data of temperature,wind speed,water vapor pressure,cloud cover and other meteorological elements provided by CRU TS 4.04,as well as the highresolution radiation satellite data provided by CERES,to analyze the characteristics of the dry and wet evolution trends of the Indo-China Peninsula in the past 60 years.And do further research on its causes.The main conclusions obtained are as follows(1)The SPEI of the Indo-China Peninsula has been slightly reduced in the past 60 years.The areas with significant drying are mainly concentrated in eastern Thailand,Yunnan and southern Myanmar.Precipitation is the leading factor leading to the drying of the entire IndoChina Peninsula in the past 60 years.On seasonal scale,the change in dryness and wetness in winter is subject to changes in reference evapotranspiration,and precipitation changes in other seasons are the dominant factor.(2)The reference evapotranspiration of the Indo-China Peninsula has shown an increasing trend in the past 60 years.Spatially,the reference evapotranspiration of some grid points in northern Vietnam and central Myanmar has decreased,while the resting grid points has increased.The change in water vapor pressure difference is the main reason for the increase in reference evapotranspiration in the Indo-China Peninsula.The effect of wind speed is second only to the change in water vapor pressure difference.(3)SPEI grew slightly in 1961-1973 and 1993-1999,and decreased slightly in 1974-1992 and 2000-2016.Except for the time period from 2000 to 2016,the dominant factor affecting SPEI changes is reference evapotranspiration,and the other three dominant factors affecting SPEI changes are precipitation.(4)The reference evapotranspiration in 1961-1973 and 1993-1999 showed a downward trend,and the reference evapotranspiration in 1974-1992 and 2000-2016 showed an increasing trend.The dominant factor for the two periods of 1961-1973 and 2000-2016 was the change in wind speed.The dominant factor for 1974 to 1992 was net radiation,and the dominant factor for 1993-1999 was the water vapor pressure difference.