| Aerosol climate effect has attracted more attention, and sulphate has become the important object of aerosol climate effect research due to its great emission and radiation forcing。The dissertation falls into 3 parts:1) Evaluation of CAM3 simulation capability。Comparing the simulation results without considering sulfur effect with satellite observations and finding the good agreement besides certain difference in value, e.g. lower cloud fraction, it can be induced that CAM3 can simulation the factors of hydrological cycle and reproduce the distribution of cloud fraction, precipitation and water vapor.2) Simulation of sulphate direct climate effect. The modeled sulphate load is 2.97mgSO4/m2 after removing other aerosols except sulphate, displacing with SO2 value from AeroCom emission in 2000 and making sure sulfur cycle reacting with other physical and dynamic processes. The effect of sulphate is seasonal and regionally, like grater in summer than spring, greater in north hemisphere than southern one. Then change happening between 15oN-60oN is notable. The change trend of cloud, precipitation and water vapor mostly appears a peak and a trough, and surface temperature decreases and the largest difference is in summer. Between 0~30 oN, precipitation water vapor decreases but in winter, precipitation decreases increases only in winter, and water vapor decreases in summer. The change is weaker between 40oN~60oN: surface temperature decreases in summer and increase in spring and winter, cloud fraction decreases in summer and decrease in winter, precipitation increases in summer and autumn and decreases in winter. The change trends of cloud fraction, precipitation and water vapor are similar, however, every variable distributes not evenly in space but difference in difference place.3) Simulation of sulphate first indirect climate effect. Hydrological cycle factors are investigated after sulphate first indirect effect is combined through displacing CCN parameter with new one considering sulphate effect on cloud droplet radius. CDNC is great different between over land and sea: CDNC varies between 140~180cm-3 over land in most regions of 1st and 4th layer of model, while less than 80cm-3 ove r sea. CDNC change rapider with high in lower layer than higher layer. Due to highest concentration in East China, its CDNC can equal 200cm-3. Effective radius distributes similarly with CDNC. Typical value in 1st layer is 6~8μm, and maximum value 8μm is in Africa and South America. The effective radius is larger in north Pacific coast, north equator and 60oS region of 4th layer, varying between 9~15μm. Shortwave cloud forcing increases in most regions varies between 0 ~ -25 W/m2 and increases more over sea than land. The value changes largest in region 55oN, the relative is largest in region 30 oS. Cloud fraction, precipitable water, precipitation, and water vapor changes larger in north hemisphere than south one. Cloud fraction change larger in 60oN region, and the relative change of high cloud and mid-level cloud is larger, so the uncertainties associated with vertical distribution of the sulphate can not be ignored. Precipitable water mostly decreases in north hemisphere, and it decreases most in summer. Precipitable water change larger mostly above 400hPa, and change rapider with high in lower layer than higher layer. Precipitation rapidly swings and appears more than one peak or trough. The extent of precipitation is largest around equator, and the change swings more rapidly here in spring and autumn. Specific humidity at 850 hPa pressure surface decreases in north hemisphere, meanwhile, the relative change increases with latitude. The value decreases most in region 60oN in summer. In other seasons, value decreases in north hemisphere, further more, it decreases notably over Qinghai-Tibet Plateau. Specific humidity at 850 hPa pressure surface also decrease in certain extent in Bie Plateau in winter.
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