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Research Progress南亚夏季风爆发提前加速青藏高原湖泊扩张
The advanced South Asian monsoon onset accelerates lake expansion over the Tibetan Plateau
[2019-09-10]
【中文介绍】
近十几年来青藏高原湖泊快速扩张,引起了广泛关注。有限证据表明,气候变暖和冰冻圈变化是近年来湖泊扩张的主要原因,但两者对湖泊扩张的贡献仍存在较大争议。近期有研究指出,青藏高原内陆湖泊湖水量的增加主要来源是净降水量的增加,而冰川融化则是湖泊扩张的次要原因。本文主要利用卫星反演的湖泊面积和各种观测资料以及再分析数据,分析了南亚夏季风爆发对青藏高原湖泊变化的可能影响。
定量的湖泊水量收支结果表明,净降水量的增加是目前青藏高原湖泊扩张的主要因素。而南亚夏季风爆发日期、青藏高原五月降水以及高原湖泊面积在年代际变化趋势上存在高度的一致性。当南亚夏季风爆发提前, 5月青藏高原南部水汽输送增强,上升运动增强,局地降水增多。5月降水增量约占青藏高原东部地区年降水量增量的50%,从而为青藏高原中东部大型湖泊的扩张提供了充足的水源。研究结果可为认识青藏高原湖泊扩张对气候变化的响应提供重要的科学支持。
【英文介绍】
Observational evidence is presented to show a significant increasing trend of lake area in the Tibetan Plateau (TP). The quantitative lake volume budget has suggested that the net increased precipitation could be the predominant contributor to the lake expansion. This study mainly investigates the source of the increased precipitation and examines the impact of advanced Southern Asian monsoon (SAM) onset on the lake variations. The great consistency of decadal shift varied from SAM onset, TP precipitation and lake area variations, indicates that the advanced SAM onset would play an important role in modulating lake variations. The enhanced water vapor transportation and strengthened ascending motion in May over the southern TP result in more precipitation. Consequently, the increment of precipitation in May accounts for approximately 50% of annual precipitation increase over the eastern Inner Tibetan Plateau (ITP), which provides adequate water supply increase for large lake expansion.
【关键图表】
图1. (a)青藏高原湖泊(面积大于10km2)变化趋势空间分布图,(b)青藏高原站点月平均降水趋势以及降水比例,(c)青藏高原五月平均降水变化趋势图,以及各个气象站五月平均(d)降水和(e)气温变化趋势空间分布图。
Fig.1. The changing characteristics of lake area and meteorological variables over the Tibetan Plateau (TP). (a) The spatial pattern of linear trends of 364 lakes with area surface covering more than 10 km2. The diagram in the top right corner depicts the temporal variation of total lake area averaged over 364 lakes. The shading plot depicts the elevation of the TP. (b) The histogram indicates the proportion of climatological monthly accumulated precipitation to the annual amount (red), and the linear trend of monthly accumulated precipitation (blue) during the period of 1976 to 2016. The five-pointed star indicates the linear trend is significant at the 99% confidence level. (c) Time series of the accumulated precipitation in May, and the blue curve indicates the result of a nine-point sliding average. The spatial distribution of (d) accumulated precipitation and (e) surface air temperature (SST) in May over the TP using in-situ daily meteorological observation, respectively.
【引用格式】
Liu, Y., H. Chen, G. Zhang, J. Sun, H. Wang, 2019: The advanced South Asian monsoon onset accelerates lake expansion over the Tibetan Plateau. Science Bulletin, doi: https://doi.org/10.1016/j.scib.2019.08.011.