A layered energy-separating algorithm of net radiation in the operational two-layer model

In many two-layer models, Beer's Law was adopted to separate net radiation of mixed pixel. However in many cases, the difference of albedo and surface temperature between vegetation and soil is often very large. Soil's temperature can be m ore than 10 degrees C than vegetation's. Therefore, the error is large for the separation of net radiation using Beer's Law. Net radiation is composed of short wave net radiation in visible and near-infrared band and long wave net radiation in thermal-infrared band. Therefore, in order to achieve it, besides the separation of radiometric temperature of mixed pixel, albedo of mixed pixel must be separated. Theoretical basis of the layered energy-separating algorithm of net radiation was analyzed. Instantaneous soil evaporation and transpiration and carbon dioxide assimilation flux of vegetation in North China were retrieved based on MODIS data and simultaneous measurements of Dongping Lake. The obtained results showed that the layered energy-separating algorithm of net radiation is reasonable and feasible. In addition, uncertainty of the algorithm was discussed.