Medium Resolution Remote Sensing Data Based Spatial And Temporal Distribution Of Drought In China During The Past 30 Years

Basing on the research project,the present study used AVHRR and MODIS data,set the index system to describe the drought.According to the index system,we analyzed the Spatial Distribution and Temporal Variation of Drought in China and typical districts of drought.Firstly,correlational analyses were conducted between soil moisture and drought monitoring index to find the index system.We found that temperature vegetation dryness index(TVDI)is the most sensitive index to drought.Then,the study improved the TVDI by DEM correction and dry edge correction.Combining with the drought class index,the study formed the dry index system.Secondly,the study obtained the dataset of the long time series of drought.At last,analyzed the distribution characteristics of drought and get the evolutionary trend of drought by using the tendency rate analysis.The result of the study as followed:(1)The study used moisture data and remote sensing data to analyze the sensibility of TVDI and other drought monitoring index to drought.The results show that comparing to other drought monitoring index,Temperature vegetation dry index is the most sensitive index to drought,and can be the index system of drought.(2)The study improved the TVDI by DEM correction and dry edge correction.The result shows that after improving,the TVDI is more sensitive to soil moisture than before.(3)The study obtaining drought class-based thresholds by fitting function that came from improved index and soil moisture.According to the thresholds,the study obtained the space-time distribution and frequency of drought.The results indicate that Xibei area,southwest of Xizang are the high rate of drought occurrence places in China during the past 30 years.Yunnan-guizhou plateau is the drought center of south west of China.Drought centers are located in east of Hebei,south east of Hebei and middle part of Shandong in Huang HuaiHai Plain.(4)The study obtained the average frequency of the study area and then gained the trend fate of drought frequency.Results indicate that,drought occurrence increase during the past thirty years,but it is not sustained growth year by year.The frequency of severe drought increased significantly,while increase of light drought is slow than moderate drought and severe drought.Drought increase in Huanghuaihai Plain,But the tendency is different to increase of the whole China.The present study using AVHRR and MODIS vegetation and temperature data,according to the methodology of "Index system set-the analysis of Spatial distribution-drought Temporal Variation",analyzed the Spatial distribution characteristic and Temporal Variation of China drought.The results of the study can provide the reference of China drought research and provide data support for climate change and the relationship between climate change and food production.