内蒙古温带荒漠草原生长季地表反射率特征及数值模拟

Characteristics and numerical simulation of surface albedo in temperate desert steppe in Inner Mongolia

基于内蒙古苏尼特左旗温带荒漠草原生态系统野外观测站2008年生长季(5月1日—10月15日)的气象和生物要素观测资料,分析了地表反射率日、季动态,并构建了温带荒漠草原地表反射率模型.结果表明:研究区地表反射率日变化主要受太阳高度角影响,呈早晚高、中午低的U形曲线特征;生长季地表反射率在0.20～0.34,平均为0.25,以5月较高、6月下降、7—9月相对稳定、10月增大;研究区地表反射率的季节动态与冠层叶片的物候变化有关,同时受降水过程的影响;土壤含水量和叶面积指数是影响该区地表反射率的关键因子;反映土壤含水量和叶面积指数共同作用的地表反射率模型的模拟值与野外实测值具有较好的一致性.

Based on the meteorological and biological observation data from the temperate desert steppe ecosystem research station in Sunitezuoqi of Inner Mongolia during growth season （from May 1st to October 15th,2008）,the diurnal and seasonal characteristics of surface albedo in the steppe were analyzed,with related model constructed. In the steppe,the diurnal variation of surface albedo was mainly affected by solar altitude,being higher just after sunrise and before sunset and lower in midday. During growth season,the surface albedo was from 0.20 to 0.34,with an average of 0.25,and was higher in May,decreased in June,kept relatively stable from July to September,and increased in October. This seasonal variation was related to the phenology of canopy leaf,and affected by precipitation process. Soil water content （SWC） and leaf area index （LAI） were the key factors affecting the surface albedo. A model for the surface albedo responding to SWC and LAI was developed,which showed a good performance in consistent between simulated and observed surface albedo.