中东亚中全新世气候与植被反馈作用:PMIP2多模式结果分析

文章选取了参加国际古气候模拟比较计划(Paleoclimate Modeling Intercomparison Project,简称PMIP)的6个耦合气候模式的模拟结果,着重对中全新世中东亚干旱区以及东亚季风区的夏季气候变化(气温、降水)进行分析,探讨了植被反馈作用对这3个区域中全新世气候变化的影响。由于各个模式之间以及所用的植被模块的差异,它们模拟的气候变化(气温、降水)的幅度有所不同,本文利用PMIP 2中6个模式的模拟结果分析,结果发现,在中全新世轨道因素的影响下,3个区域的平均温度和降水都有所增加。而中全新世植被的变化在: 1)东亚季风区,各个模式模拟的结果也各不相同,其中FOAM,ECHAM5.3-MPIOM127-LPJ和MRI-CGCM2.3.4FA这3个模式的模拟结果显示温度较现代低,而ECBILTCLIOVECODE,UBRIS-HADCM3M2和MRI-CGCM2.3.4NFA模式的模拟结果显示植被的变化导致地表温度较现代高,但各个模式对东亚季风区的中全新世植被变化所引起的降水变化并不理想,并且差异较大; 2)中东亚干旱区,ECBILTCLIOVECODE,FOAM和UBRIS-HADCM3M2模式的模拟结果表现出中全新世植被的变化导致中东亚干旱区夏季平均温度较现代低,而其他3个模式的模拟结果则表现出较现代高的趋势,但除MRI-CGCM2.3.4NFA模式外,其余5个模式均在中国西北新疆地区表现出0.5℃左右的降温,而几乎所有的模式都在中东亚干旱区表现出降水增加; 3)中亚地区,在温度方面,除了MRI-CGCM2.3.4NFA随着植被的变化表现出了较大的增温幅度外,其余5个模式夏季温度随着植被变化不大;而在降水方面,除了FOAM模式外,其他5个模式结果都显示出区域平均降水的增加。由此可见,在中全新世东亚季风区、中东亚干旱区以及中亚地区,除了太阳辐射等因素,植被对气候变化也有重要影响。

THE IMPACT OF VEGETATION FEEDBACK ON MID-HOLOCENE CLIMATE IN CENTRAL AND EAST ASIA: RESULTS OF 6 COUPLED SIMULATIONS FROM THE PALEOCLIMATE MODELING INTERCOMPARISON PROJECT(PMIP)

The role of vegetation feedback on the climate in response to insolation forcing during the mid-Holocene was investigated by using results from six coupled ocean-atmosphere-vegetation general circulation models and coupled ocean-atmosphere general circulation models in the Paleoclimate Modeling Intercomparison Project Phase 2(PMIP 2). Temperature and precipitation changes compared to pre-industrial(1750A.D.)control runs in summer(June to September)at the Mid-Holocene in three areas were analyzed:(1)Central Asia whose climate is affected by South Asian monsoon and Westerly wind; (2)Arid Central Asian area is marched with Westerly wind and Asian monsoon; (3)East Asian monsoon area is mainly influenced by East Asian monsoon.For the different models and the vegetation models used by the different models,there are variations in the mean temperature and precipitation changes(6ka-0ka)across models.Feature common to all models include warmer temperature and more precipitation through analysis of the results of the mean summer temperature and precipitation changes.Since vegetation changes are different in different areas between different models,the vegetation feedback on the climate in response to insolation forcing is different across models and areas.In East Asian Monsoon area,the results show different variations between different models.FOAM,ECHAM5.3-MPIOM127-LPJ and MRI-CGCM2.3.4FA modeled temperature show lower temperature compared to pre-industrial control runs.Results from ECBILTCLIOVECODE,UBRIS-HADCM3M2 and MRI-CGCM2.3.4NFA show that the improved vegetation cover leads to a warmer mean summer surface temperature.But the precipitation changes caused by the vegetation cover changes are quite different and the results are not ideal.In the arid Central Asia,ECBILTCLIOVECODE,FOAM and UBRIS-HADCM3M2 modeled results show that the improved vegetation cover changes lead to a lower mean summer surface temperature.But the other models results show that the improved vegetation cover changes lead to a warmer mean summer surface temperature.All models show the mean summer surface temperature is about 0.5℃ lower than present in Xinjiang area of North West China except MRI-CGCM2.3.4NFA.There is cross-model change in the variance of the mean summer precipitation in the arid Central Asia.In Central Asia,when the vegetation covers coupled in the models are improved, all models show a little difference in mean summer surface temperatures except MRI-CGCM2.3.4NFA, and all models show more mean summer precipitation than present except FOAM. Thus it can be seen,except for insolation forcing,vegetation cover changes has an important effect on climate change in the research areas during the mid-Holocene.