基于迹线方法的黄河源区降水来源分析

Moisture Source Analysis of the Yellow River Headwater Region Using the Lagrangian Trajectory Method

黄河源区是青藏高原生态屏障的重要组成部分,也是黄河的主要水源地,具有重要的生态环境与社会经济意义.本文基于拉格朗日迹线观点,利用自主研发的高效并行大气迹线求解软件pyTraject获得黄河源区1980~2018年全部6h累计降水量大于1mm的降水来源迹线,采用水汽源归因法对这些降水进行溯源分析,并采用已有的类似软件hysplit进行对比验证.结果表明,黄河源区降水中有43%左右的水汽由青藏高原贡献;青藏高原、南亚和四川盆地的水汽贡献对黄河源区的降水变化起主导作用;青藏高原东南部、四川盆地、柴达木盆地等地对黄河源区降水的水汽贡献呈显著增长趋势.基于拉格朗日观点的降水来源解析可为更好地理解区域的水物质循环,尤其是空中的水物质输送过程,以及其历史演变过程提供参考依据.

The Yellow River headwater region(YRHR),an important part of the Qinghai-Tibetan Plateau that supplies 38% water resource of the whole Yellow River, has very important ecological, environmental, social and economic values.In this paper, we proposed an efficient parallel software pyTraject, to calculate atmospheric moisture transport trajectories from reanalysis atmospheric data, and to attribute moisture sources of precipitation.We applied the pyTraject to back trace precipitation events with intensity higher than 1 mm/6 h over the YRHR from 1980 to 2018,using wind, precipitation and specific humidity data from the ERA-interim reanalysis dataset.We also compared our results with the popular hysplit software, and obtained generally consistent results, which show that: the Qinghai-Tibetan Plateau supplies about 43% moisture to the YRHR precipitation, and dominates precipitation variation along with the South Asia and the Sichuan Basin;the moisture supply from the southeast of the Qinghai-Tibetan Plateau, the Sichuan Basin, and the Qaidam Basin shows an increasing trend.From this case study, it can be inferred that moisture source analysis using Lagrangian methods can help us to learn the atmospheric-hydrological cycle of water resources, as well as its variation, of a study basin.