Spatial And Temporal Variation Of Drought And Causes Of Climate Driving In Three Northeast Provinces

With the aggravation of global warming,the problem of water shortage is becoming more and more prominent.Drought has an aggravating trend all over the world,and often accompanied by heat waves.The interaction between drought and heat waves aggravates the severity of disasters.The direct economic losses caused by drought in China are up to tens of billions of yuan every year,while the three northeastern provinces are the largest granaries and important forestry bases in China,and the impact of drought on them is more serious.Therefore,it is of great practical significance to carry out drought research in the three northeastern provinces.Therefore,this paper chooses three northeastern provinces as the research area to explore the spatial and temporal variation of drought situation and its causes.Firstly,the monthly scale meteorological station data of the study area are used,and the trend analysis of precipitation,temperature and standardized precipitation evapotranspiration index(SPEI)is carried out by the non-parametric test analysis method of TFPW-MK.On this basis,the spatial and temporal decomposition of SPEI is carried out by using the distinct empirical orthogonal function(DEOF),and its temporal and spatial characteristics are analyzed.Secondly,the frequency of drought,heat waves and compound drought and heat waves is studied by using daily temperature and monthly Palmer drought severity index(sc_PDSI).The remote correlation between climate driving factors and sc_PDSI is analyzed by using wavelet analysis.The main contents and achievements of this paper include:(1)Using precipitation and temperature data of 83 stations in three northeastern provinces on monthly scale,the trend of precipitation and temperature in the study area is analyzed,the trend distribution map of the whole study area is drawn,and the variation law of different regions is analyzed and summarized.The average precipitation and temperature anomaly curves of the three northeastern provinces in the whole study period and crop growing season are made.(2)Calculating SPEI using precipitation and temperature data of 83 stations,and showing the calculation results of SPEI in the study area as a whole.On the premise of ensuring the reliability of the calculation results,this paper stud the changing trend of SPEI(i.e.the changing trend of drought),and get the changing law of drought index.Then this paper uses DEOF to decompose SPEI into two drought sub-regions.The characteristics and time characteristics were analyzed and compared with the historical drought events to verify the reliability of the arid sub-region.(3)In order to avoid errors caused by spatial difference,the daily-scale grid temperature data and monthly grid sc_PDSI are used to define high-temperature heat waves and compound droughts and heat waves.The frequency of drought,heat waves and compound droughts and heat waves are analyzed.The periodicity of sc_PDSI and climate driving factors is obtained,and the teleconnection between them is explored.Based on the above research,this paper analyses the drought situation in the three northeastern provinces.Starting from meteorological factors,the drought in the study area is characterized by SPEI in time and space.The frequency of drought,heat waves and compound droughts and heat waves are analyzed and summarized by grid-scale temperature and sc_PDIS data.Finally,the wavelet analysis is used to analyze the drought.The remote correlation between sc_PDSI and climatic driving factors is given,and the causes of drought are explored,which provides an important reference for water resources management in the three northeastern provinces.