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以1992~2012年长江流域196个土壤观测站的旬土壤相对湿度资料为基础,通过线性趋势和Kriging插值等方法分析0~50 cm土层土壤相对湿度年际、年内时空分异和季节变化特征,并从气候和NDVI要素探寻其变化原因。结果表明:(1)长江流域年均土壤相对湿度自1992年以来整体上呈波动增加趋势,年际变化倾向率为0.26%/a。江源地区土壤相对湿度增幅大于其他地区。(2)土壤相对湿度表现为东南和西南部较高,东北和西北部较低的空间分布特点。(3)四季土壤相对湿度增加的强烈程度由大到小依次是秋季、冬季、夏季、春季。(4)土壤相对湿度增加的主要原因是潜在蒸发减少和NDVI增加。
Based on the ten-day soil relative humidity data of 196 soil observatories in the Yangtze River valley from 1992 to 2012, the spatial-temporal variability and seasonal variation of soil relative humidity in 0 ~ 50 cm soil layer were analyzed by linear trend and Kriging interpolation , And from climate and NDVI elements to explore the reasons for its change. The results show that: (1) The annual average relative humidity of the Yangtze River Basin has been fluctuating generally since 1992, and the interannual change tendency is 0.26% / a. The relative increase of soil moisture in Jiangyuan area is greater than that in other areas. (2) The soil relative humidity showed the higher spatial distribution in the southeast and southwest, and the lower in the northeast and northwest. (3) The intensity of soil relative humidity increase in four seasons is autumn, winter, summer and spring. (4) The main reason for the increase of soil relative humidity is the decrease of potential evaporation and the increase of NDVI.