末次盛冰期以来中国北方干旱区演化及短尺度干旱事件

对中国北方干旱区329个古土壤和湖泊沉积物的14C年龄数据的时空分布及频数统计分析表明, 从末次盛冰期至冰消期, 我国整个干旱区受控于西风带；在全新世, 干旱区东部环境变化主要受控于东亚季风系统, 而其西部仍属西风控制区。全新世以来, 中国干旱区存在至少4次百年至千年级的干旱事件, 且干湿变化基本上与全球西风模式区的气候变化相反, 而与低纬非洲干旱区气候变化有很好的对应关系 。由于我国干旱区和非洲干旱区的干湿变化均受控于来自低纬热带海洋的夏季风的强弱, 因此　两区干旱事件的同时发生可能与低纬热带海洋的气候变化有关。同时, 本文利用14C年龄的时空分布和其它地质资料, 初步恢复了末次盛冰期和全新世最适宜期我国干旱区的沙漠分布状况。

EVOLUTION AND DROUGHT EVENTS IN ARID REGION OF NORTHERN CHINA SINCE THE LAST GLACIAL MAXIMUM

Based on 329 reliable radiocarbon dates of palaeosol and lake sediments from arid region in northern China, we demonstrate here that Chinese arid region environment changes were controlled by Westerly in glacial, but the east part of the Chinese arid region was controlled by Asian Monsoon at Holocene. The environment in arid region has been affected by at least four times of arid events during Holocene, which are in agreement with the evidences of pollen, lacustrine in all China and the Pacific eolian records. Environment changes in arid region of China reverse to the region controlled by Westerly. However, this variation is closely correlated with the Sahara. Because the environment in northern China and Sahara is affected by summer monsoon from tropic sea in low latitude, the existence of these arid intervals that happened at the same time may attribute to climate changes of tropic sea. Combining the temporal and spatial distribution of the 14C dates, and with some other geological dates, we reconstructed the distribution of desert at the last glacial maximum and the Holocene Optimum. The eastern boundary of desert withdrew from about 125°E to 117°E, and the southern boundary retreated 38°N nearby. The desert distribution at the last glacial maximum and the Holocene Optimum will provide better constrains for sensitivity test experiments with General Circulation Models to isolate the impact of dust and albedo on regional and global climate changes.