干旱区生态环境知识资源中心

In this paper, we present five-year (2000-2004) climatological statistics of Northern Hemisphere spectral white-sky albedo for the 16 International Geosphere-Biosphere Program (IGBP) ecosystem classes when accompanied by the presence of snow on the ground. These statistics are obtained using validated, high quality Moderate Resolution Imaging Spectroradiometer (MODIS) land surface albedo (MOD43B3) data flagged as snow in the associated Quality Assurance (QA) fields. Near Real-Time Ice and Snow Extent (NISE) data are used as an additional discriminator of snow extent. Statistics are provided for the first seven MODIS bands, ranging from 0.47 to 2.1 mu m, and for three broadbands, 0.3-0.7, 0.3-5.0 and 0.7-5.0 mu m.

The statistics demonstrate that each ecosystem classification has a discernible spectral albedo signature when accompanied by snow on the ground. This indicates that winter canopy and the underlying surface radiative properties are impacted by the presence of snow overlying these surfaces. For example, the 0.47 mu m albedo of winter snow-free evergreen needleleaf forests increases from 0.03 to 0.36 in the presence of snow, compared to an increase of 0.04 to 0.76 for croplands. In general, the albedo of snow-covered ecosystems with some winter canopy has lower albedos than ecosystems with little to no winter canopy; for example the 0.47 mu m albedo of snow-covered mixed forests is 0.39 compared to 0.87 for barren/deserts and 0.95 for permanent snow.

These statistics can be used within land surface models in a stand-alone mode, to prescribe albedo values in atmospheric General Circulation Models (GCMs), or be incorporated into research and operational projects. They are intended to provide researchers with representative spectral albedo values of IGBP ecosystems in the presence of snow that are derived from validated satellite data. (c) 2007 Elsevier Inc. All rights reserved.