基于ESA CCI遥感数据的山西省土壤水时空变化特征及影响因子分析

Spatial-Temporal Variation Characteristics and Influencing Factors of Soil Moisture in Shanxi Province Based on ESA CCI Remote Sensing Data

土壤水分在调节陆地-大气水循环及能量收支平衡中起着重要作用,已有研究大多基于实验的方法探讨土壤水分的变化规律,然而对于大尺度区域和长时间土壤水序列的分析存在一定的局限性。卫星遥感监测能够提供大面积、全天时、全天候的数据,其中欧洲空间局(European Space Agency,ESA)气候变化项目(Climate Change Initiative,CCI)遥感土壤水分数据因具有“长时间序列、高精度”等特点,使其成为研究土壤水分变化规律的主要数据来源,可为大尺度农业旱情评估和预警提供一定的数据支撑。因此,以2000-2015年ESA CCI遥感土壤水分数据为基础,结合归一化植被指数(NDVI)和气候数据等,对山西省的土壤水分时空演变规律进行分析,并采用相关性分析法和主成分分析法探讨了土壤水分与NDVI、降水量、气温以及风速之间的相关关系,从而确定影响山西省土壤水分时空变化的主要因子。结果表明:山西省土壤水分整体呈“南部、北部低,中部高”的分布特征,且空间分布特征具有一定的稳定性。近16 a来,山西省土壤水分变化整体呈不显著上升趋势,其倾向率为0.0006 a^(-1)。采用相关性分析法得知土壤水分与NDVI、降水量、气温呈正相关关系,与风速呈负相关关系。结合主成分分析法最终确定影响山西省土壤水分变化的主要因子是NDVI和降水量,其次是气温以及风速。

Soil moisture(SM)plays an important role in regulating terrestrial-atmospheric water circulation and energy balance.Most of the existing studies have explored the dynamic patterns of SM based on experimental methods.However,the analysis of large-scale regions and long-term SM sequences was limited.Satellite remote sensing monitoring can provide large-area,all-day,all-weather data.The remote sensing soil moisture data from the Climate Change Initiative(CCI)of the European Space Agency(ESA)is a major source of data for studying soil moisture patterns due to its"long time series and high accuracy".It can provide some data support for large-scale agricultural drought assessment and early warning.Therefore,based on the ESA CCI remote sensing soil moisture data from 2000-2015,combined with normalised vegetation index(NDVI)and climate data,etc.,this paper analyzed the spatial and temporal evolution of soil moisture in Shanxi Province.The correlation analysis method and principal component analysis method were used to discuss the correlation between soil moisture and NDVI,precipitation,air temperature and wind speed,so as to determine the main factors affecting the temporal and spatial changes of soil moisture in Shanxi Province.The results showed that the overall distribution characteristics of soil moisture in Shanxi Province were"low in the south and north,high in the middle",and the spatial distribution characteristics had a certain stability.In recent 16 years,soil moisture change in Shanxi Province showed an insignificant upward trend,with a tendency rate of 0.0006 a^(-1).It was found through correlation analysis that soil moisture was positively correlated with NDVI,precipitation and air temperature,and negatively correlated with wind speed.Combined with principal component analysis,it was determined that the main factors affecting soil water change in Shanxi Province were NDVI and precipitation,followed by air temperature and wind speed.