摘要
利用美国国家大气研究中心(NCAR)的CCSM2全球气候系统模式以及重建的古地理资料研究了晚白垩世(80Ma)东亚的古气候特征。模拟结果表明:80Ma时期东亚地区大范围盛行的风向和气压系统随季节有显著变化,由此可以推断东亚地区当时是存在季风环流的。与现代气候比较,白垩纪时期大陆上空的大气环流系统经向特征更明显,这种特征可能与当时欧亚大陆东西向跨度较小有关。此外,在当时偏暖的背景下,东亚冬季风和夏季风呈现出一致的变化特征,即冬季风和夏季风都比现代强。年平均降水的分布型和现代的情况比较相似,降水最大值出现在10°S～10°N的赤道辐合带中,与西太平洋相邻的大陆东岸降水也较多,其中心超过1200mm,而在中纬度的内陆地区降水则稀少。虽然与现代情况相似,80Ma在30°N附近的西太平洋上也为多雨带,然而在东亚陆地上没有多雨带,这说明了青藏高原隆升在现代东亚夏季梅雨形成中的重要性。此外,模拟的80Ma时期东亚地区气候要比现代温暖,相同纬度的表面气温要高2℃以上,模拟的温度与地质证据估计的温度比较接近。
In this paper,the East Asian climate during the Late Cretaceous（80 Ma）is examined by using the Community Climate System Model Version 2（CCSM2）from the National Center for Atmospheric Research（NCAR）and the reconstructed palaeogeographic data.The simulation results show that the large-scale prevailing wind directions and pressure systems over East Asia showed a remarkable seasonal variation during 80 Ma,so that it can be inferred that there existed a monsoon circulation over East Asia at that time.Compared to the present climate,the atmospheric circulation systems over the Eurasian continent in the Late Cretaceous showed a stronger meridional feature,which possibly corresponded to a smaller zonal span of the continent.Moreover,under a warmer background in the Late Cretaceous,the winter and summer monsoons over East Asia showed a synchronous variation,with a stronger winter monsoon as well as a stronger summer monsoon.The pattern of annual mean precipitation is similar to that of the present climate,with the maximum precipitation appearing in the intertropical convergence zone（ITCZ）between 10°S and 10°N.There was also more precipitation over the eastern coasts of the continent adjacent to the western Pacific,with the central value exceeding 1200 mm,and there was less precipitation in the mid latitudes of the inland areas.Although a more precipitation belt also appeared near 30°N over the western Pacific,which is similar to the present climate,there was no precipitation belt over the land of East Asia.This feature implies that the uplift of the Tibetan Plateau plays an important role in the formation of the present bai-u rain（plum rains）.Moreover,the simulated climate over East Asia during 80 Ma was warmer relative to the present one and surface air temperature is 2 ℃ higher at the same latitudes compared to the present climate;the simulated temperature is close to the estimation from the geological evidence.
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2009年第6期226-239,共14页
Earth Science Frontiers
基金
国家基础研究发展计划"973"项目(2006CB701400)
关键词
晚白垩世
温室气候
古气候模拟
Late Cretaceous greenhouse climate paleoclimate modeling
