Estimating the water vapor transport pathways and associated sources of water vapor for the extreme rainfall event over east of China in July 2007 using the Lagrangian method
Estimating the water vapor transport pathways and associated sources of water vapor for the extreme rainfall event over east of China in July 2007 using the Lagrangian method
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作者：
Shi Xiaohui
2007年7月，中国中东部地区发生了一系列极端降水事件，造成了毁灭性的洪涝灾害和基础设施的破坏，许多人被卷走。基于NCEP/NCAR分析资料提供的气象场和天气研究预报模式输出分别驱动的粒子扩散输送模式FLEXPART，回溯了大量粒子(气团)的运动轨迹。它在极端降雨区上空形成密集的三维网格阵列进行初始化，并根据过程中的降水确定水汽的输送路径。同时，还研究了中国东部降水的可能蒸发源及其数量贡献。10天的回溯分析结果表明，这次事件最初与副热带大陆和热带海洋的水汽输送有关。在输送过程中，在青藏高原强地形增强和副热带高压屏障的共同作用下，每个气团都可能经历多个蒸发-降水周期，蒸发源虽然分布在大部分地区，但对降水的贡献主要集中在副热带大陆，特别是印度半岛、缅甸和中国西南部的四川、云南等省(约40%)，这表明上游地区的土壤湿度异常为极端降水提供了良好的指示。
In July 2007,a series of extreme precipitation events occurred over the middle and eastern parts of China,which caused the devastating flooding and considerable infrastructure damage and swept off many people.Based on the particle dispersion transport model FLEXPART,which is driven by the meteorological fields provided by the NCEP/NCAR analysis data and the outputs of the Weather Research and Forecasting(WRF) Model respectively,a very large number of particles(air parcels) trajectories were tracked backward.It initialized in a dense three-dimensional grid array located over the extreme rainfall region and was followed by determining the transport pathways of the moisture according to the precipitation during the event.As well the possible evaporative sources of the precipitation falling over the eastern part of China and their quantitative contributions were investigated.The ten days back-tracking analysis results show that this event was initially related with the transport of subtropical continental and tropical ocean moisture.During the process of transport,every air parcel might experience several periods of evaporation-precipitation in which it was significantly influenced by the combined action of the strong orographic enhancement of the Tibetan Plateau and the barrier of subtropical high pressure.Although the evaporation source was distributed over large parts of the areas,the major contribution to the precipitation is over the subtropical continent,including especially the Indian Peninsula,Myanmar and Sichuan and Yunnan Provinces over the southwestern part of China(approximately 40%).This indicates that the abnormal soil moisture over the upstream areas provides with a good indication for the extreme precipitation.