MIS3晚期典型阶段气候模拟的初步研究

LATE MIS 3 CLIMATE SIMULATIONS

我国大量地质资料反映了全球海洋氧同位素 3阶段 (MIS 3)晚期具有间冰阶海侵、暖湿的气候环境特征。对这一阶段的气候成因论证 ,将为现代温室效应的气候增温提供重要的历史相似型。本文使用含有陆面过程的全球 9层大气环流谱模式 (AGCM +SSiB) ,采用地球轨道参数驱动的太阳辐射、北半球第四纪冰盖和东亚植被预置的下垫面对 35kaB .P .气候进行了敏感性模拟试验。研究结果表明 :(1 )MIS 3晚期中、低纬度大部分大陆全年温度增加 ,欧亚大陆腹地气温增高主要是冬季增温贡献 ,反映太阳辐射变化通过大气环流作用引起的更加显著的气候效应。南北海陆水汽交换的加强首先使低纬度季风区降水收益。 (2 )相当于LGM 50 %规模的第四纪冰盖不仅仅具有高纬度区降温效应 ,还强化了辐射纬向差异造成的南北温差 ,从而增强了水汽从低纬度区向高纬度区输送的能力 ,使青藏高原、南亚和非洲季风区的降水进一步增加。 (3) 35kaB .P .东亚植被对辐射的低纬度区增温具有增强效应 ,而对冰盖高纬度区降温具有减缓效应 ,结果扩大了欧亚内陆的降水增加范围 ,使中国高降水带向北推移。 (4)中国各大区域 35kaB .P .气候类型不尽相同。当中国东部与太平洋在同纬度带的热力差异减小时 ,东西向水汽输送减弱 ,造成东部沿海降水减少 ;但当欧?

Geological records from China have proved that the late Marine Isotope Stage 3 (MIS 3) of 35ka B.P. should be characterized by a warm-wet climate and a large transgression. In this paper the late MIS 3 climate was simulated with a global nine-level atmospheric circulation model (AGCM+SSiB) on the basis of considering such conditions as insolation,glaciation, and surface conditions. The modeling results have deepened ours understanding of the MIS 3 climate and its influence factors. First, the annual temperature increased in most mid-low latitude areas. Temperature increase within Eurasian continent was mainly due to winter temperature increase, a contribution made by insolation through atmospheric circulations. Precipitation increase in low latitude monsoon areas benefited mostly from increased exchange of land-ocean moisture from south to north. Second, Quaternary icesheets not only caused temperature decline in high latitude areas,but also enhanced the south-north temperature difference caused by differential insolation. This produced a high transportation capability of moisture from the low latitudes to the high, resulting in increase of monsoon precipitation in the Tibetan Plateau,South Asia and Africa. Third, East Asian vegetation accelerated insolation-induced temperature raising in the low latitudes,but delayed icesheet-induced temperature decline in the high latitudes,resulting in enlargement of Eurasia precipitation areas and northward moving of Chinese rain-belts. Finally, Chinese climate shows such a pattern: with decrease of thermodynamic difference at the same latitude of Eastern China and the Pacific, a weakened east-west moisture transportation thus caused made the precipitation in eastern coastal areas of China dropping down, while with increase of temperature difference between the Eurasia continent and low latitude oceanic areas, a increased south-north moisture exchange thus caused was in favor of increasing precipitation in Chinese inland areas. $$$$