The Temporal And Spatial Distribution Characteristics Of Droughtin China Based On A Self-calibrating Palmer Drought Severity Index

Itis very significance to guide the agri cultural productionby defining the development trend of drought.Based on th e comparison and analysisall kinds of drought index,this paper choose a self-calibrating palm er drought severity index s pace applicabilityas drought index analysis.Based on the data of precipitation,tem perature and the available water holding capacity for 1951-2012 years in 659 m eteorological stations in china,use the model of self-calibrating palmer drought sev erity to ca lculate the P DSI values of each site,choose spatial interpolation in ArcGIS and Morlet wavelet m ethod to analysis the tem poral and spatial variation of precipitation,tem peratureand drought in China.In order to provide reference basis fordrought control droughtrelief and drought prediction in the country and each area.Get the main conclusions as follows:(1)Except northwest,the precipitation in China mainly shows a decreasing trend,and the temperature is on the rise as a whole.Th e national average precipitation decreased significantly from 1950 s to 1960 s,decline was slow in the mid in 1960 s to early twenty-first Century.The spatial variation of precipitation was significant,pr ecipitation in m ost areas of Northwest China has increas ed obviously in the last 60 years;The precip itation in Northeast China has obvious characteristics of age variation,Before 1980 s,the decrease was obvious.The precipitation in 80 s and 90 s was m uch higher,and the first ten years of twenty-first Century were significantly smaller;the precipitation in the eastern part of Northwest China and parts of North China is basically decreasing in the la st 60 years.In m ost parts of the north,the temperature rises considerably,while in m ost parts of the south the temperature changes are not very obvious.(2)From the time scale,the drought shows an increasing trend,and there are m any time scales of periodic oscillation.Drought intensity showed an in creasing trend in China,among which 1950 s was relatively humid.From 1960 s to 1990 s,dry and wet alternated,and from the middle of 1990 s showed obvious tendency of drying.And the range of drought has increased greatly.The variation trend of moderate drought and severe drought is consistent w ith light drought,but the range is small.The wavelet periodic oscillations of drought in the year and the four seasons are sig nificant at the tim e scales of 4,7,1 1,15 and 28 a.Sunspot activity existsthe 11 aperiodicity in the Haier(magnetic),indicating that the a nnual SC-PDSI index is strongly influenced by solar activity.About 4a period of oscillation is similar with atmospheric circulation 2-4 a cycle and El Nino 2-7 a cycle,show that besid es solar ac tivity,the SC-PDSI index is affected by the atmospheric circulation and El Nino events.(3)The difference of spatial distribution of drought in China is rem arkable.The frequency of drought is mainly between 33% and 50%,The drought frequency in the summer and autumn is slightly higher than that in spring and winter.The spatial distribution of drought intensity is basically consistent with drought frequency,indicating that the more frequent drought occurs,the drought are more intensity.In the past 60 years,most areas in Northwest and some parts of Tibet have a tendency to becom e wet.In Northeast China,central China and southern part of China have a trend of dry.(4)There is a positiv e correlation between precip itation and PDSI,and negativ e correlation between temperature and PDSI.On the tim e scale,before 1990 s,the correlation between PDSI and precipitation was better,and in 90 s an d later the correlation between temperature and temperature was better.This shows that the sudden increase of temperature in the early 1990 s is the main fact or leading to the drought increase.At the spatial scale,there is a good correspondence between precipitation and PDSI,It shows that precipitation has a great influence on the change of drought in most parts of the country.In the northeast,North China,as the temperature rises,the drought increases,indicating that the temperature in these areas has a significant impact on PDSI.