毛乌素沙地周边地区相对湿度与NDVI变化研究

Changes of relative humidity and NDVI in Mu Us peripheral area

利用1981—2015年GIMMS NDVI长时间序列数据集,对毛乌素沙地周边地区相对湿度和植被指数变化进行研究。基于GIS与遥感基础,从时间性、空间性、稳定性三角度进行分析。结果表明:(1)1981—2015年,毛乌素沙地周边地区平均相对湿度整体表现为波动变化中存在下降趋势,但2006—2015年相对湿度呈上升趋势;其空间上呈现由东南向西北逐步减少;沙地边缘相对湿度变率小于宁夏平原、黄河流经地段及东南部山地段。(2)近35年,毛乌素周边地区NDVI呈现增加趋势,2006—2015年NDVI值快速上升;其空间上呈现东部、东南部高,西北部低。(3)NDVI与降水量呈显著正相关,与相对湿度呈正效应。气候较稳定期(1981—1996年),NDVI与降水量、相对湿度变化趋势一致;气候快速升温期(1996—2015年),退耕还林致NDVI值呈增加状态的同时也减弱了降水量与相对湿度的下降程度。毛乌素沙地周边地区植被的增加在一定程度上缓解了快速增温对相对湿度的负效应。

Using the 1981-015 GIMMS NDVI long-time series data set, the changes of relative humidity and vegetation index around Mu Us sandy area were studied. Based on GIS and remote sensing, analysis was done from the perspective of time, space and stability. ①From 1981 to 2016, the relative humidity of Mu Us peripheral the area showed a decreasing trend, but the relative humidity has increased from 2006 to 2015. The space distribution change trend is from southeast to northwest and gradually reduced. The relative humidity at the edge of the sand is less variable than the Ningxia Plain, with the Yellow River flowing through the lot and the southeastern part of the mountain. ②In the past 35 years, NDVI has increased in Mu Us peripheral area, and between 2006 and 2015, NDVI rose rapidly. Spatial rendering mode is the east and southeast high, north- west low. （3） NDVI was positively currelated with precipitation, and had weak positive conrelation the relativehumidity. In the lelatively stable climate （1981- 1996） , NDVI showed the same tlend with plecipitation and relative humidity. In the period of rapid climate warming （ 1996-015 ） , the NDVI value of letuming land for fainting to foreswy is increasing, and it also weakened the decline of precipitation and relative humidity. To a certain extent, the increase of vegetation in the area around Mu Us desert alleviates the negative effect of rapid wamreing on relative humidity.