利用GLDAS资料分析黄土高原半干旱区土壤湿度对气候变化的响应

利用GLDAS资料分析了1948~2010年黄土高原半干旱区气温、降水和土壤湿度的变化趋势,并重点讨论了气温和降水对土壤湿度的影响和相对贡献。结果表明:近60 a来黄土高原半干旱区整体呈现暖干化趋势,增温速率明显高于全球平均增温速率;不同深度的土壤湿度的长期变化均呈减小趋势,且年际间变化明显。不同深度的土壤湿度和气温呈负相关关系,并随着土壤加深,两者的相关性加强;土壤湿度和降水则呈正相关关系,相关关系最大出现在表层土壤。通过分析气温和降水在不同季节对土壤湿度的相对贡献发现,春季和冬季气温对土壤湿度的相对贡献较降水显著,秋季恰好相反,夏季气温和降水对土壤湿度的相对贡献大小相当。对比不同深度层降水、气温对土壤湿度的相对贡献得出,降水对浅层土壤湿度有显著作用,而气温对深层土壤湿度的作用更明显。

Analysis of Response of Soil Moisture to Climate Change in Semi - arid Loess Plateau in China Based on GLDAS Data

The variations of air temperature, precipitation and soil moisture are analyzed over semi - arid region of Loess Plateau from 1948 to 2010 by using GLDAS data, and the relative contributions of air temperature and precipitation to soil moisture are highlighted. The results show that there was a warming and drying trend in the recent 60 years in the semi - arid region of Loess Plateau, and the warming rate was higher than the global average wanning trend. The long - term variations of soil moisture in different layers showed a decreasing trend with a clear interannual change. There was a negative correlation between soil moisture and air temperature in all lay- ers, and with the increase of soil depth the correlation enhanced. On the contrary, a positive correlation could be observed between precipitation and soil moisture and the largest correlation coefficient appeared at the surface layer. By analysing the relative contribu- tions of air temperature and precipitation to soil moisture in different layers and different seasons, it could be found that air temperature had a significant contribution to soil moisture in spring and winter, while precipitation had an obvious contribution to soil moisture in fall. In summer, precipitation and air temperature had an equivalent contribution to soil moisture. Additionally, in four seasons it showed that precipitation significantly affected soil moisture in shallow layers, while air temperature affected it in deep layers.