利用黄土高原及其周边区域91个气象站1961 -2010年间年、月气象数据和4个农业气象观测站19 a(1981-1999年)的土壤湿度和20 a(1992-2011年)的土壤相对湿度资料,分析了该地区代表站点农田土壤湿度和主要气象要素的年、月变化以及土壤湿度对气候变化的响应.研究主要利用了线性趋势和相关分析等方法.结果表明:(1)黄土高原近50a来的降水呈减少趋势,气温呈上升趋势.多年平均年降水量(气温)的地理分布特点是南多(高)北少(低),东多(高)西少(低),由东南向西北递减,受到海拔高度和地形的影响,半干旱区和半湿润区有整体南移的趋势.(2)不同年份气候、环境等条件变化使得西峰、长治、延安、绥德4个站点10～ 50 cm土壤湿度存在年际间差异.(3)土壤湿度与气温之间存在负反馈关系,与降水之间存在正反馈关系.温度和降水条件的变化是导致黄土高原土壤湿度变化的主要原因.(4)以西峰为例,分析了黄土高原地区水熟变化对土壤湿度的影响.就表层土壤而言,各季土壤湿度与本季和前一季度乃至前一年气温均为负相关关系,与降水量呈正相关.就较深层土壤而言,土壤湿度与降水和气温的相关关系因季节而异.从月尺度上看,土壤湿度与气温普遍存在负相关关系,而与降水之间总体响应不明显,但在某些月份两者存在显著相关性.%We analyzed the temporal evolution tendency characteristics of temperature, precipitation and soil moisture on the Loess Plateau of China and the response of soil moisture to climate change ( mainly about temperature and precipitation) by using annual and monthly meteorological data of 91 meteorological stations within and around the Loess Plateau from 1961-2010 and the soil moisture data from 4 agricultural meteorological stations from 1992-2011. The major methods were linear trend analysis and correlation analysis. The results indicated that: (1) The precipitation on the Loess Plateau in recent 50 years declined gradually, while the temperature increased gradually. The geographical distribution characteristics of mean annual precipitation (temperature) was that the southern part was higher than northern part, the eastern part was higher than the southern part. The temperature and precipitation descended from southeast to northwest gradually, which was determined by altitude and terrain. Semiarid and semi humid area had overall southward trend. (2) The change of different year's climate, environment conditions leaded to the change of top 50 cm soil moisture condition in Xifeng, Changzhi, Yanan, Suide among different years. (3) Soil moisture had a negative feedback to temperature but il had a positive feedback to precipitation. Temperature and precipitation changes were the main reasons of variation of soil moisture on the Loess Plateau. (4) In a case study of Xifeng, the climate change trend and its effect on soil moisture, as well as the evolution of soil moisture were analyzed. During the period between 1991 and 2010, in terms of topsoil moisture, it negatively correlated with temperature but precipitation positively correlated with it. While in terms of the deep soil, the correlation relationship between soil moisture and temperature, precipitation varied depending on the seasons. On the scale of month, soil moisture had a response to climate. There was a negative correlation relationship between temperature and soil moisture, some of them had reached significant level. Actually soil moisture had no obvious response to precipitation, but reached significant level in some months.
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