青藏高原腹地多年冻土区地表反照率的季节变化及主要影响因子

准确获取青藏高原地表反照率的季节变化特征对高原地表能水循环研究具有重要意义。本文利用青藏高原多年冻土区西大滩和唐古拉2007年的气象及辐射数据,运用相关分析方法研究了太阳高度角、积雪及活动层冻融过程对地表反照率变化的影响。结果显示:冷暖季降雪过程中地表反照率的变化差异较明显;地表无积雪覆盖期间,地表反照率与气温和表层土壤含水量呈反相关关系。利用多元回归分析法构建了以积雪日数和气温为影响因子的月均地表反照率计算回归方程,经检验与观测值对比平均相对误差为7.1%,可用于青藏高原北部地表反照率的估算。

Seasonal Changes and Major Influencing Factors of Surface Albedo in the Permafrost Regions of the Qinghai-Tibet Plateau Hinterland,China

The seasonal variation of surface albedo and its accurate acquisition are of great significance for the study of the land surface energy and water cycle in the Qinghai-Tibet Plateau.Based on the meteorology and radiation data in 2007 at automatic meteorological stations including Xidatan(XDT)and Tanggula(TGL)(operated by Crysphere Research Station on Qinghai-Tibet Plateau,CAS),the effects of solar altitude angles,snow cover and active layer freezing and thawing process on the changes of surface albedo were studied via correlation analysis in the permafrost regions of Qinghai-Tibet Plateau.The results showed obvious changes in surface albedo during snowfalls in cold and warm seasons and the soil moisture and air temperature were reversely correlated with the surface albedo in the process when there was no snow.Referring to snow cover days and air temperature,the monthly average surface albedo was calculated via multivariate regression analysis.The test results indicated that the average relative error between the calculated and the measured value was 7.1%,which could be used to estimate the surface albedo in the northern part of Qinghai-Tibet Plateau.