A study of regional and long-term variation of radiation budget using general circulation model

The analysis of solar radiation at the surface has great importance for the investigation of climate change, because scattering and absorption of solar radiation by gases and aerosol particles can result in a net decrease in global irradiance that reaches the ground. It's said that we attribute climate change in the 20 century to the activity of humans. Now we can understand relation between human activity and climate change by investigating the long-term radiation budget trend. Goal of this study is to investigate anthropogenic effect on climate change by estimating change of radiation budget. In this study, we used aerosol transport model, called SPRINTARS [Takemura et al., 2000, 2002, 2005]. This model is coupled with CCSR/NIES/FRCGC Atmospheric General Circulation model and treats carbonaceous, sulfate, mineral dust and sea salt aerosols from various emission sources. Aerosol particles can influence the radiation budget not only directly by scattering and absorbing radiation, but also indirectly by changing the property of cloud that is the important role in climate change. The indirect effect can be divided into two categories and our model treats the first and second indirect effect. Furthermore we compared the model simulation results with the surface observed data. We have a good correlation between observed data and model simulation in seasonal and annual trends. Observed data and model simulation result show that anthropogenic aerosol increase caused solar radiation decrease in the industrial regions such as China where economic development is happening. Then we analyzed details of the dynamical hydrological cycle in this region and found that surface temperature change caused by aerosol reducing sunshine affected clouds and precipitation. While we calculate contributions of each factor from our model simulations because there are some factors influencing solar radiation.