摘要
地球轨道参数驱动的太阳辐射变化造成了中全新世北半球大陆夏季的普遍增温 ,但中低纬度的冬季温度低于现代。古气候模型和古植被模型在这个动力驱动基础上 ,对东亚季风区的模拟均反映了北半球中低纬度的冬季温度低于现代 ,由此主要受冬季温度控制的中纬度森林植被向南迁移。然而 ,根据花粉资料重建的中全新世植被表明 ,中国东部森林植被带向北迁移 ,其中常绿阔叶林北移 30 0 km,落叶阔叶林北移 50 0 - 60 0 km。根据古植被类比研究 ,中国东部冬季温度普遍增温 ,东北、华北、长江中下游地区的冬季温度比现代分别高出 3.5,2 .3,3.1 - 4.0°C。数据和模型之间的巨大差距表明了引起中全新世植被和温度变化的气候动力 ,并不完全受地球轨道驱动的太阳辐射变化控制 ,而早、中全新世大陆下垫面 ,包括海冰、冰流以及植被和土壤的变化 ,对气候系统和大气环流格局有着潜在的重要反馈作用。本文提出东亚地区自全新世初期至中全新世 ,由于北半球高纬海冰退缩、第四纪冰流消融已尽、欧亚大陆永久冻土面积缩小 ,导致欧亚大陆冷源作用削弱。冬季西伯利亚高压减弱 ,造成东亚冬季风变弱。而冬季风强度和范围减小 ,使中国东部冬季温度增高 ,是森林植被向北迁移的重要气候动力因素。
The orbit forcing theory suggests that the insolation at 6ka was lower than at the present in winter season in low and middle latitudes. This driving climate has been simulated by palaeo GCMs showing a lower than present winter temperature in East Asian. The palaeoclimate driven vegetation has been simulated by biome models showing the mid Holocene forest vegetation was shifted southwards in China. However, the palaeovegetation reconstructed by a great of pollen records displays the forest zones migration systematically northwards when compared with the present. These vegetation patterns are used to furthermore reconstructed the climate which reflect a warmer than present winter in China. As there existed huge different or contrasting results between geological observations and model simulations, we recognized that dynamic mechanisms can not be only limited in the orbit forcing. The land surface feedback in Asian monsoon regions could play a greater important role than direct insolation anomaly.
出处
《微体古生物学报》
CSCD
北大核心
2000年第2期147-154,共8页
Acta Micropalaeontologica Sinica
关键词
花粉
植被带
冬季风
中全新世
中国
迁移
pollen, biome, winter temperature, winter monsoon, land surface, mid Holocene, China
