基于MODIS数据的华北地区遥感干旱监测研究

选择4种遥感干旱监测模型，与土壤相对湿度（RSM）和自校准帕默尔干旱指数（sc-PDSI）进行相关性分析，并探讨了研究区生长季干旱的时空变化特征。结果表明：作物缺水指数（CWSI）和植被供水指数（VSWI）更适合监测华北地区的土壤水分，在草原区和农区CWSI干旱监测较好，在森林区和荒漠区VSWI干旱监测效果较好；研究区干旱化趋势有所减缓，且2007—2011年为干旱到湿润的转折区间；干旱空间分布呈北部大于南部、西部大于东部的变化趋势，阿拉善高原的干旱最严重，而大兴安岭山脉基本无干旱发生；干旱整体上向好的趋势发展，尤其是鄂尔多斯南部、山西省、燕山山脉和华北地区-东北地区交界处的农区，且易旱区重心有向西移动的趋势，该成果可以为区域农业干旱监测提供一定的参考。

Remote Sensing Drought Monitoring of North China Based on MODIS Data

In order to struggle with drought proactively and reduce the adverse effect of drought on agriculture, animal husbandry and forestry production in North China, it is necessary to take effective monitoring measures to reflect the drought accurately and timely in North China. However, the existing drought researches only apply a single drought index to areas with relatively homogeneous underlying surface, and rarely consider the applicability of remote sensing drought index under the influence of different underlying surfaces. Therefore, the North China with a more complicated underlying surface is selected as the study area. This study area is a typical climate vulnerable area in China, and it is also an area where the contradictions between population, resources and environment are more serious. In order to provide an effective scientific basis for the decision-making of drought control and drought resistance in the region, an appropriate drought index, on the basis of verification, is selected to analyze the temporal and spatial characteristics of drought in North China. Based on MODIS data, the crop water stress index (CWSI), vegetation water supply index (VSWI), conditional vegetation temperature index (VTCI) and temperature vegetation drought index (TVDI) of the crop growing season (April-October) from 2001 to 2018 were retrieved. Correlation analysis was conducted with relative moisture of soil at 10cm and self-calibrated Palmer Dryness Index (SC-PDSI). At the same time, the appropriate remote sensing drought index was selected to analyze the spatiotemporal variation characteristics of drought in North China through cumulative anomaly analysis, Sen trend analysis, Mann-Kendall test method and gravity center transfer theory. The results show as follows: 1) The four remote sensing drought indexes have better monitoring effects on the moisture of surface soil, but CWSI and VSWI are more suitable for monitoring soil water in North China, and CWSI is more sensitive to soil drought monitoring. In addition, the CWSI drought monitoring effect is better in the grassland and agricultural areas, while the VSWI drought monitoring effect is better in the forest and desert areas. 2) The drought trend in North China has slowed down. The more severe drought years are 2001-2007 and 2009, and 2007-2011 is the transition period from drought to humid. 3) The spatial distribution of drought in North China shows a trend that the north is larger than the south, and the west is larger than the east. The Alashan Plateau has the most serious drought, while the Greater Khingan Mountains almost has no drought. In addition, VSWI is more representative in describing the percentage of the area occupied by drought grade in the entire North China. The percentage of the area occupied by drought grade in descending order is: no drought>extreme drought>moderate drought>mild drought>severe drought. 4) The drought in North China showed a good development trend as a whole. Drought mitigation effect is better in most areas, especially the agricultural areas in southern Ordos, Shanxi Province, Yanshan Mountains and the junction of North China and Northeast China. In addition, the center in drought-prone areas tends to move westward on the whole. Selecting the two most suitable drought indices on the basis of verification to monitor drought in North China can better reveal its temporal and spatial changes. CWSI and VSWI can be used in regional drought research, which can make up for the defects of large scale heterogeneous underlying surface drought research, and can effectively reveal the spatiotemporal characteristics of drought on complex underlying surface. This is of great significance to the sustainable development of regional agriculture, animal husbandry and forestry. The research results of this paper, such as CWSI and VSWI can more accurately reflect the research results of surface soil moisture to a certain extent, could provide references for regional agricultural drought monitoring, and provide scientific basis for regional disaster prevention and mitigation decisions.