西藏地区土壤湿度时空变化特征

Temporal and Spatial Distribution of Soil Moisture in Tibet

为了揭示西藏地区土壤湿度季节和区域性变化特征及其与气候要素的相互影响,基于1980—2009年西藏地区土壤湿度资料以及西藏38个站点的气温、降水资料,笔者分析了西藏地区土壤湿度的时空分布特征及其与气温、降水的相关关系。结果表明:近30年来西藏地区年及季节土壤湿度呈现自西北向东南逐渐递增的分布规律,最小值位于阿里地区,最大值在墨脱以南地区,其中秋季土壤湿度最大,其次是夏季,春季最小。年、季土壤湿度均表现为1980s—1990s减少,随后增加的趋势。年、季土壤湿度在20世纪90年代末有显著增加突变点。春季土壤湿度与西藏大部分地区的春、夏降水呈正相关,夏季土壤湿度与西藏沿江一线、东部地区的同期降水呈正相关。

The paper aims to investigate the seasonal variation and regional characteristics of soil moisture in Tibet, and their relationship with meteorological factors. The temporal and spatial distribution characteristicsand their relationship with air temperature and precipitation were analyzed on the basis of soil moisture dataand mean air temperature and precipitation data of 38 meteorological stations in Tibet during 1980- 2009.Results showed that： the annual and seasonal soil moisture increased from the northwest part to the southeastpart of Tibet, and the minimum and maximum values were located in Ngari and the southern Motuo of NyingchiRegion, respectively. The maximum value of soil moisture appeared in autumn, followed by that in summer, theminimum value appeared in spring. The annual and seasonal soil moisture decreased from 1980 s to 1990 s,then increased. Both the annual and seasonal soil moisture had an increasing mutation point in late 1990 s. Thesoil moisture in spring had a positive correlation with precipitation in most parts of Tibet in spring and summer,and the soil moisture in summer had a positive correlation with the precipitation along the Yarlung Zangbo River and the eastern Tibet.