摘要:利用2001~2016年MODIS月平均液相云水路径（Cloud Liquid Water Path，LWP）、冰相云水路径（Cloud Ice Water Path，IWP）资料和ERA-Interim再分析等资料，分析了青藏高原空中云水的分布特征、变化趋势以及与大气环流变化和水汽输送变化的关系。结果显示，LWP和IWP的年平均分布形态与降水、可降水量对应较好，林芝地区聚集了丰富的LWP、IWP、降水量和可降水量。受印度洋季风影响，LWP和IWP存在明显的季节变化，夏季LWP和IWP最丰富，冬季最少。水汽传输和高原的动力、热力作用是影响夏季LWP和IWP分布的主要因素，夏季高原南部相对湿度大，水汽抬升强烈，促进了LWP和IWP的形成和积累。LWP和IWP随海拔高度的变化特征较为相似，3000~5500 m海拔高度区间内二者的总体变化特征与青藏高原降水的梯度变化特征一致，为随高度先较快升高后保持稳定的分布特征。青藏高原年平均和季节平均LWP和IWP在2001~2016年间均以减少趋势为主，这一变化趋势与云量和降水变化趋势一致，LWP和IWP的减少趋势与水汽输送通量散度的增加密切相关。
关键词:液相云水路径/
冰相云水路径/
气候特征/
青藏高原/
MODIS数据
Abstract:Analyses of cloud liquid water path (LWP) and cloud ice water path (IWP) over the Tibetan Plateau are performed with MODIS monthly data, ERA-Interim reanalysis data and other datasets during the period of 2001-2016. The distribution features, trends and relationships with circulation and water vapor transport are examined. Results show that the annual means of LWP and IWP are of the similar distribution shapes with precipitation and precipitable water. The Nyingchi region has accumulated abundant LWP, IWP, precipitation, and precipitable water. LWP and IWP have obvious seasonal variations because of Indian Ocean Monsoon and they are the most abundant in summer and scarce in winter. Water vapor transport, dynamical effect, and thermodynamic effect of the Tibetan Plateau are the main influencing factors for the distributions of LWP and IWP in summer. In southern Tibetan Plateau, the relative humidity is high and the vapor rises strongly, which promotes the formation and accumulation of LWP and IWP. LWP and IWP show a similar variation patterns with elevation. And their general variation pattern in the interval of 3000 to 5500 m is agreed with the variation pattern of precipitation gradient. They quickly increased with elevation and then gradually become stable. Decreasing trends of annual mean and seasonal mean of LWP and IWP are found in the period of 2001-2016 and the similar trend is also found for cloud amount over the Tibetan Plateau. The increasing trend of the divergence of water vapor flux is the closely related with the decreasing trends of LWP and IWP.
Key words:Cloud liquid water path/
Cloud ice water path/
Climatic characteristic/
Tibetan Plateau/
MODIS data
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