地表植被改变对气候变化影响的模拟研究

由于人类活动的影响，在过去的几百年里全球植被发生了很大的变化。地表植被的变化通过地面的能量和水汽交换而改变气候，研究目的是通过数值模拟认识这一过程的有关气候效应。方法上使用AGCM+SSIB模式对由于植被变化而可能导致的气候变化进行了敏感性模拟试验，研究区域为欧亚大陆。模拟主要对1700年、1800年、1900年、1950年所代表的气候特征时期植被改变所造成的气候变化响应进行平衡态试验。欧亚大陆在这些时段内植被变化是非常明显的，有大片的土地覆盖从森林变为草地或者耕地，或者从自然草地变为耕地。结果表明地表植被的改变对于气候的作用是非常复杂的，但中纬度地区在统计上有着比较明显的作用。得出的主要结论是，从1700年到1950年由于植被的退化，东亚地区夏季变得更热而冬季变得更冷，欧洲冬夏都变冷了；中国南部的降水在夏季不断减少，亚洲夏季风被削弱。

Simulating the Effect of Changed Vegetation on the Climate Change in Eurasia

The global land cover has been changed in the last hundreds of years due to human activity.Land cover change(LCC) affects climate through the surface energy and moisture budgets.The purpose of this study is to understand the climatic effects of these physical processes by numerical simulation.We used an AGCM+SSiB model to simulate the sensitivity of climate changes due to the land cover change.The studying area is Eurasia.Equilibrium climatic state simulations were conducted in summer and winter by using estimated land cover for the years of 1700,1800,1900,1950 and 1990.Each simulation experiment run 11 years and the average of the results of the last 10 years represents mean climate state.The LCC between these periods was extensive over Eurasia,where large area altered from forest to either grass or crops,or from natural grassland to crops.Results show that the effect of LCC on climate change is very complex,and there are statistically significant impacts in the most middle latitudes.We can summarize some primer conclusions.With the degradation of vegetation from 1700 to 1950,in East Asia the climate was warmer in summer and colder in winter and in Europe it was both colder.The summer precipitation in South China decreased while the Asian summer monsoon was weakening.From 1950 to 1990,the effects are not significant because the LCC is not obvious compared to the time before 1950.