Surface and Planetary Albedo over the Tibetan Plateau

Using the ISCCP satellite data the method of determining the surface albedo over the Tibetan Plateau is discussed. On the snow-free surface, the broadband surface albedo can be calculated using radiation model based on the visible albedo provided by ISCCP. It is assumed in the calculations that the ultraviolet albedo and the ratio of the near infrared to visible albedo are both constant. It is found by sensitivity study that the assumptions would not introduce significant error in the calculations. On the mixed snow and snow-free surface, the broadband surface albedo can be expressed directly by the ISCCP visible albedo. The test results have been compared with the surface observations and agree well with them except in the desert areas. The planetary albedo in clear day over Tibetan Plateau is also computed. It is found by comparison with the ERBE satellite observations that the aerosols in the desert area around the Plateau have a significant influence on radiation budget from May to September. In the rest months, however, the effect of aerosols can be neglected. The results of model calculations are generally in good agreement with the ERBE measurements.