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利用2010年DOY 209期的Terra/MODIS 16 d合成的植被指数(EVI)产品数据MOD13 A2和8 d天合成的地表温度(LST)产品数据MOD11 A2,构建LST-EVI特征空间,从而得到了条件温度植被干旱指数TVDI反映的藏北土壤湿度空间分布图。结合野外同步土壤表层水含量测试数据,二者表现出较好的相关程度,并通过0.05水平的显著性检验。对藏北地区土壤湿度的空间格局和分异规律分析,研究结果表明:①藏北全区TVDI值呈正态分布,东部地区偏湿,中部地区多数为正常湿度,而西部TVDI直方图分布形状与全区相似,但偏旱;②藏北地区不同气候区划内土壤湿度分异较大,那曲高山谷地亚寒带半湿润区土壤湿度最高,其空间变异也最强烈,青南高原亚寒带半干旱区土壤干旱最严重;③研究区内土壤湿度空间分布受海拔影响较为明显,在海拔4500 m以下的地区土壤湿度随海拔升高而降低,此后,土壤湿度随着海拔升高而升高。
The LST-EVI feature space was constructed using the Terra / MODIS 16-day composite vegetation index (EVI) product data MOD13 A2 and the 8-day combined surface temperature (LST) Spatial Distribution of Soil Moisture in Northern Tibet Reflected by Temperature Vegetation Drought Index TVDI. Combined with the field synchronous soil surface water content test data, the two showed a good correlation, and passed the 0.05 level of significance test. The spatial pattern and differentiation of soil moisture in northern Tibet showed that: (1) The TVDI values of the whole area of northern Tibet showed a normal distribution, while the eastern part of the region was wet with most of the normal humidity in the central part, while the TVDI histogram of the western part Which is similar to the whole region but arid; (2) The soil moisture in different climatic zones in northern Tibet is quite different. The soil moisture in the sub-humid zone is the highest in Naqu alpine valley, and its spatial variability is also the strongest. The subtropical semi-arid zone The most serious soil drought was the spatial distribution of soil moisture in the study area. The spatial distribution of soil moisture in the study area was more obvious under the influence of altitude. The soil moisture in the area below 4500 m elevation decreased with elevation, and then the soil moisture increased with the elevation.