Comparison of observed and modelled radiation budget over the Tibetan Plateau using satellite data

Abstract

AbstractThe radiation budget over the Tibetan Plateau is investigated using radiation models together with the data from the International Satellite Cloud Climatology Project (ISCCP) and the Earth Radiation Budget Experiment (ERBE). A method of using the ISCCP spectral surface albedo in determining the radiation budget is proposed and tested against observations. Three cloud levels (low, middle, and high) with different phase states are considered in the radiative simulations. The effect of dust aerosols on the radiation budget is also taken into account in the study. The simulations are performed using climatology monthly mean radiosonde profiles observed at 35 stations on the Tibetan Plateau and compared with the ERBE observations.The results indicate that the radiation budget in clear sky conditions can be well modelled using the monthly mean radiosonde data. The monthly mean total scene radiation budget is also simulated satisfactorily using the radiation models in conjunction with the ISCCP data, although significant discrepancies can be found in certain regions owing to uncertainties in the calculations. The cloud properties over this high plateau are found to be different from elsewhere. The most significant differences in the cloud properties are their altitude, which is much higher, and water content, which is less than at lower altitudes. As a result, cloud over the Tibetan Plateau has positive forcing in the winter and less negative radiative forcing in the summer compared with low altitudes.