EFFECT OF CLOUD AND SURFACE ALBEDO ON DIRECT SULFATE RADIATIVE FORCING OVER EAST ASIA

Areg ional climate model is used to investigate the effect of clouds and surf ace albedo on direct sulfate radiative forcing over East Asia.The annual directradiative forcing (DRF) from cloud regions is estimated.In the final,the effects of sulfate upon the surface and atmospheric solar radiation budget are also discussed respectively.The simulated results indicated that the effect of cloud upon the DRF of sulfate is generally to weaken the forcing,this weakening depends on cloud cover and cloud optical depth.The annual cloudy-sky DRF is approximately -0.097 W/m2 for our simulated domain,and the cont ribution to the total DRF from cloud-sky regions is approx imately 10.4%.It means that the DRF from cloud-sky regions can not be negligible in spite of cloud strongly weakening the DRF of sulfate aerosol.High surface reflect ance tends to enhance the DRF of sulfate,while low surface reflectance tends to weaken the DRF of sulfate.The effect of sulfate on atmospheric radiation balance is very small.However,sulfate aerosol leads to a reduction in the surf ace solar irradiance and the reduction is very similar in magnitude and spatial distribution to the solar radiative forcing at the top of the model.