Implications of lake level variations at 6 ka and 18 ka in mainland Asia

The inland lake level changes in arid or semi-arid mainland Asia at 6 ka and 18 ka have been reconstructed by means of survey of literature through compilations of sedimentological, biogeological and hydrological data. The results show that most lakes identical in low water stands at present. But the lakes from East and South Asia are characterised by a lower water levels at full glaciation while the lakes in Northwest Asia are registered higher stands. Conversely, comparative higher lake levels are registered in East and South Asia and lower lake levels appeared in Northwest Asia at 6 ka. Between above two regions, there occurred a climatic transitional zone centred in the area ranged from Central Asia north-eastward to west Mongolian Plateau and south-westward to the Middle East, where the lake behaviors are close to the lakes from Southeast Asia at 6 ka but change to be similar to the lakes from Northwest Asia at 18 ka. This lake level changes in temporal and spatial pattern indicated the global-scale alternation of atmospheric circulation associated with the shifts of westerlies and variation of summer monsoon intensity. The interpretation of changes in lake level and the reconstructions of atmospheric circulation are comparable with GCMs simulated moisture change induced by the change of internal and external forcing during last glacial maximum and mid-Holocene. (C) 1998 Elsevier Science B.V. All rights reserved.