植被功能型差异对地表反照率时空分布的影响分析

Influence of the Difference of Plant Functional Types on Surface Albedo Variation

地表反照率是表征地球表面捕获太阳辐射能力的特征参量,是影响气候系统的关键因素。植被通过物理（反照率）和生物过程（蒸散）影响陆地区域的能量收支过程,进而调控区域气候特征,其中陆表植被的变化及其可能的反照率影响规律受到了研究者的重视。以北京地区为例,利用MODIS地表反照率产品,结合地表覆盖类型产品中的植被功能型数据,计算并分析了2008~2013年北京地区典型植被功能型差异对地表反照率时空分布的影响。结果表明：北京地区典型植被功能型共6种,按其平均地表反照率从大到小依次为：谷物作物、城市用地、灌丛、落叶阔叶林、常绿针叶林及水体。因不同植被功能型的分布及变化对地表反照率的时空分布有直接影响,北京地区平均地表反照率总体呈东高西低、南高北低趋势,秋季最小,冬季次之,春、夏较大,且2008~2013年地表反照率呈现变化量约为-0.79×10-3/a的缓慢减小趋势。

Surface albedo is the key parameter to quantify solar radiation budget on land surface,which deeply feedback to local or regional climate system.Usually,vegetation has altered climate change by modifying energy budget in different physical（albedo）and biological processes（evaportransporation）.And physical process has become one of important factors in altering land surface process and climate change.Combined with plant functional type data with surface albedo datasets from MODIS land surface products,this study tried to examine the pattern of plant functional types and their influence on the surface albedo variation from 2008 to 2013in Beijing.The variation of Plant function type has influenced surface albedo change with their mean surface albedo from high to low in Beijing as follow：cropland,urban and built-up,shrub,deciduous broadleaf trees,evergreen needleleaf trees,water,which indicated that forest has lower albedo than crop and urban due to its high absorption for solar radiation.Surface albedo in Beijing has heterogeneous patter with high albedo in east and south,and with low albedo in west and north.Meanwhile,seasonal fluctuation of surface albedo was detected with slowly decreasing trend by-0.79×10-3 per year from 2008~2013in spring and summer.