关键词: 古湖沼学, 古气候模型, 古气候重建, 湖泊水位, 晚第四纪, 亚洲

Abstract: Lake-level changes respond to variations in regional water balance and are sensitive to climate changes. Thus it has been one of the most important indicators applied to reconstruct precipitation and water budget. Tracing long-term lake-level changes can provide references to scientific prediction of catchment floods and droughts, rational utilization of lake water resources, and protection of lake ecological environments in Asia. As there was no observed data from pre-industrial time, almost all long-term precipitation and water budget reconstructions rely on geomorphologic, sedimentologic, biogeologic and archaeological records and so on. In addition, the construction of systematic lake level databases has facilitated regional climate change research of Asia for the late Quaternary. This paper summarizes and analyzes lake-level changes in Asia over the past 30,000 years and is composed of 4 sections. Section 1 introduces the history of Asian lake level studies, construction of indicator system and lake status database, and deep-lake drilling in Asia. Section 2 analyzes time sequences of four subregions of Asia (Middle East, Central Asia, Tibetan Plateau, and East Asia) lake-level changes and infers climate conditions from the time sequences. Section 3 focuses on the spatial patterns and climate mechanisms of two key climate periods (mid-Holocene, LGM). General circulation models (GCM) and regional climate models (RegCM2) were used to reveal spatial distribution patterns of mean annual temperature, precipitation and water budget (P-E). (1) 6-ka BP (mid-Holocene): the increase in the Northern Hemisphere summer insolation led to a temperature increase in the mid-and high latitudes in Asia. Significantly enhanced Asian monsoon induced the increase of precipitation in Arabian, Indian, and Tibetan plateaus. The reduction in precipitation over southern China was linked with adjustments in the position and strength of the Pacific Subtropical High. Annual convergences over Mongolia, north-northeast China, Tibet, and India indicated more moisture and frequently wet conditions. Conversely, divergences over southern China contributed to dry conditions. (2) 21-ka BP: Annual temperatures were generally lower than today. Less precipitation over most areas of Asia and negative P-E anomalies in the Southeast Asian tropical area and East Asian lowlands were due to a weakened Asian summer monsoon and a persistent winter Mongolian High. A southward and eastward shift in the position of the Westerlies plus a decrease in evaporation in the cool conditions that prevailed across Asia led to increases in annual precipitation and P-E in west China. Section 4 provides a brief account of the importance of Asia lake-level research to the understanding of environmental changes in the future and the uncertainties about the past lake-level changes.

Key words: Asia, lake level, late quaternary, paleoclimate modeling, paleoclimate reconstruction, paleolimnology