湖泊水位资料与模型模拟恢复的6000年前全球湿润状况的对比研究

A COMPARISON OF GLOBAL MOISTURE CONDITIONS AT 6 000 YR. BP BETWEEN LAKE STATUS RECORDS AND PALAEOCLIMATE EXPERIMENTS

中文关键词:  6000年前  全球湿润状况  模型模拟  湖泊水位变化  比较研究

英文关键词:6 000 yr. BP  Global moisture conditions  Model experiments  Lake status records  Comparison

中文摘要:

      本项研究是PMIP(Palaeoclimate Modeling Intercomparison Project)国际合作项目中有关模型模拟与观测资料对比的一部分。模型试验对象是6000yr.BP的全球湿润状况。模拟试验以检测太阳辐射变化对全球大尺度气候系统的影响为主要目的。观测资料是利用地质证据恢复的古湖泊水位变化,实际上是某一地区的有效降水(降水减蒸发)的变化。通过两者的比较发现,所有模拟试验均能重现6000yr.BP在亚洲南部与非洲北部的湿润环境,从而证实了因太阳辐射变化导致的亚洲与非洲季风的增强。但模拟的季风增强无论是强度还是范围均小于地质记录。原因很可能是模拟试验中下垫面特征用“现代”的来处理。模拟试验对北半球夏季辐射增加造成的西风带北移及由此引起的中纬度地区的气候变化不够成功。绝大多数模拟对受洋流与海温影响较大的地区是失败的。主要原因可能是所有PMIP中的模拟试验都未考虑海洋的作用。

英文摘要:

      The presented research is a part of the PMIP project (Palaeoclimate Modelling Intercomparison Project) concerning the comparison between the observatory evidence and modelling experiments. The simulated objective is the global moisture condition at 6 000 yr. BP The purpose of the simulation is to verify the changes in insulation exerting the influences on the large-scale climatic systems. The observations we used are lake status records which were reconst ructed from the vario us geologic evidence. In fact, the lake level change reflects the variation of moisture conditions, particularly the effective precipitation (precipitation minus evaporation) within the lake basin. The results show that all the experiments can reproduce the wetter conditions in African and Asian monsoon areas, therefore, confirming the hypothesis of that the enhancement of Afro-Asian monsoon were induced by the seasonal change of solar radiation. But all experiments are fail to produce a broader and moreintense monsoon enhancement compared with the geologic records. The cause maybe associated with the "modern" treatment of surface coverage and thermal properties. Most experiments are incapable to model the shifts of westerlies in mid-latitudes induced by the change of insulation. Most experiments also fail to reproduce the moisture conditions from the areas where are profoundly influenced by the oceanic currents and sea surface temperature, which is likely to be related with the absence of oceanic function in the models.