In order to study global warming to predict global atmospheric change, the troposheric/stratospheric ozone, aerosols, atmospheric chemical processes, and their interactions with climate should be considered. We will explain an example of our experiments using the Earth Simulator.
 
Atmospheric Chemistry-aerosol Coupled Climate Model
Ozone in the stratosphere (ozone layer), an important climate
factor, has a beneficial role to shield us from UV light. On the other hand, ozone in the troposphere, also chemically formed from pollutants like nitrogen oxides (NOx) and hydrocarbons, can severely damage the human health and plants, and is a significant greenhouse gas. In addition, tropospheric ozone chemistry controls the lifetimes and levels of other greenhouse gases like methane (CH4), and is highly related to chemical formation of sulfate aerosol which is also an important factor for climate change and acid precipitation. Therefore, tropospheric/stratospheric ozone chemistry and aerosols should be regarded as a part of the Earth environment system. Also, for accurate prediction of climate and atmospheric environment, it is necessary to develop a climate
model which includes atmospheric chemistry and aerosols.
In the framework of the Earth system modeling of the Kyousei project, we have been developing an atmospheric chemistryaerosol coupled climate model based on the chemistry climate model CHASER*1 and aerosol model SPRINTARS*2 (Fig.1). The model, simulating detailed chemical reactions, considers effects of ozone and aerosols on the radiation and cloud processes and hence includes interaction among chemistry, aerosols, and		  

climate. Using this chemistry-aerosol component in the Earth
system model, we are becoming able to develop climate change
prediction which includes interaction with atmospheric chemistry and aerosols as well as the carbon cycle.


Atmospheric Chemistry-climate Interaction:
Experiments with the Earth Simulator
We have started several off-line simulations with CHASER on
the Earth Simulator to investigate future/past climate change
impacts on tropospheric ozone chemistry (including CH4) and aerosols. Fig.2, as an example, shows the global mean CH4 concentrations projected for the 21st century. Our simulation shows significant reduction in CH4 due to increases in temperature and water vapor associated with climate change for both scenarios. Our simulation also reveals significant feedback from future climate change to distributions of ozone and sulfate
aerosol via chemical processes. We are also planning to assess
the substantial impacts of ozone and aerosols changes on climate with our chemistry-aerosol coupled climate model.
 

Frontier Newsletter/No.27
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