我国北方地区植被类型变化气候效应的虚拟数值试验

利用区域气候模式 (RegCM 2 )对东北西部、华北北部和西北东部、华北西部两个生态环境脆弱地区植被类型分别由草地变为农田和森林后对区域气候的影响程度进行虚拟数值试验 ,结果表明 ,我国北方地区植被类型由草地变为耕地或森林将使得这些地区夏季降水减少 ,温度升高 ,5 0 0hPa位势高度升高 ,副热带高压控制地区的位势高度降低 ,从而使副高减弱 ,不利于我国北方的降水增加 .从虚拟数值试验的对比中可发现 ,华北北部、东北西部地区植被类型改变比西北东部、华北西部地区植被类型改变所引起的降水减少、温度升高和副高减弱效果显著 .此外 ,对于同一个地区的植被类型改变而言 ,由草地变为森林比由草地变为耕地所引起的降水减少、温度升高和 5 0 0hPa位势高度变化效应大 .因此 ,根据数值试验结果可知 ,退耕还草可能是我国北方干旱半干旱地区改善环境的有效方式 ,华北北部和东北西部为开展有序人类活动的最佳地区

Virtual Numerical Experiments on the Climatic Effects of Vegetation Type Changes over Northern China

Virtual numerical experiments on the climatic effects of vegetation type changes over Northern China have been conducted by using the second_generation regional climate model (RegCM2),where are regions with vulnerable ecological environment. The results show that vegetation type changes from grassland to cropland or deciduous forest result in precipitation reduction, temperature increase, and geopotential height enhancement at 500 hPa over the region of changed vegetation type in summer. The decrease of geopotential height at 500 hPa over the subtropical_high_controlled region leads to the weakening of subtropical high at 500 hPa, which is unfavorable for the increase of rainfall in the northern part of China. It is also found from the comparison of the numerical experiment results that the impact of vegetation type changes on the precipitation reduction and temperature increase is much more significant in Northern China than that in Western China, and in the same region, the effects of precipitation reduction and temperature increase are more obvious in the experiment of vegetation type changs from grassland to deciduous forest than that from grassland to cropland. Therefore, the best approach to improving the ecological environment in the arid and semiarid regions of Northern China is returning farmland to grassland, and the northern part of Northern China and the western part of Northeast China are the best regions for conducting orderly human activities.