黄土高原半干旱区陆面温度和能量的气候特征分析

Analysis of Climate Characteristics of Land Surface Temperature and Energy in the Semi-arid Region in the Loess Plateau

利用黄土高原半干旱区"定西陆面过程综合观测试验站"2004年11月至2005年10月的各种陆面物理量综合资料,比较系统地研究了黄土高原半干旱区土壤温度、降水量、地表反照率、地表辐射分量和能量平衡分量的年变化和日变化特征及其影响机制。结果显示,黄土高原陆面过程特征与其他地区有很大不同。土壤温度变化向下传播速度约为2.5~3.5 h/10cm;地表反照率随土壤湿度的增大而减小,两者的相关系数达到了0.5338;而地表反照率随降雪量增大而增大,与降雪量的相关系数为0.6645;长波辐射年最大值出现的时间比总辐射迟1个月左右,年平均日变化中地表和大气对太阳辐射加热大约需要1个小时的响应时间;潜热通量夏季是冬季的5倍多,感热通量有了两个比较明显的峰值,潜热通量、感热通量和土壤热通量的日峰值比净辐射滞后30 min^1 h。

By making use of integrated data of a variety of land surface physical parameters observed in Dingxi Synthetical Experimental Observatory of Land Surface Process in the Loess Plateau from November,2004 to October,2005,annual and daily variations characteristics of soil temperature,precipitation,land surface albedo,surface radiation components and energy balance components in the semi-arid region are systematically analyzed,as well as their influencing mechanism.Results show that the characteristics of land surface process over the Loess Plateau are different from in other regions.Downward transfer velocity of soil temperature is about 2.5~3.5 h/10cm.The land surface albedo decreases with soil moisture increasing,and their correlation coefficient is 0.5338;the land surface albedo increases with snowfall increasing,and the correlation coefficient is 0.6645.The maximum value of long-wave radiation appears later about 1 month than the total radiation.It takes one hour for solar radiation to heat the land surface and atmosphere.Latent heat flux in summer is five times more than in winter.There are two obvious peak values for sensible heat flux.The daily peak values of latent heat flux,sensible heat flux,and soil heat flux lag 30 minutes or long to one hour behind the net radiation.