青藏高原夏季陆面蒸散发对水汽输送的响应研究

Long-distance water vapor transport paths and moisture flux is a key factor expected to have widespread impacts on hydrologic cycle of The Tibetan Plateau, further, have a profound feedback on Asian monsoon and global climate change. There is a great demand for a clear-sighted view of the response characteristic of local evapotranspiration (ET) with water vapor transport variation. One of the most feasible approaches is to reveal the associated teleconnection pattern of water vapor transport characteristics with local ET. Therefore, the simulation of the Flexible particle dispersion model is implemented to retrieve the location of source region, column-integrated water vapor, water transport path, flux and divergence for teleconnection analysis with summer ET. An novel algorithm by spaceborne microwave radiometer was used to retrieve dynamic land cover fraction in pixel-wise scale for estimating the ET using SEBS by the joint observation of VIRR and MWRI sensors board on Fengyun-3B/3C satellite. And the Mann-Kendall trend test and cumulative average were conducted for detecting the variation tendency and abnormal of ET at different time scale for sub regions in Tibetan pleteau. A synthetic correlation analysis for the response of sub region ET and its abnormal with the water vapor transport characteristics of source region was made by composite correlation vector which can provide an overall view of the trajectories of water vapor transport. This project, via combined dispersion model, multi-source remote sensing ET retrieval and statistical analysis, has ability to get wider comprehension about the effect of water vapor transport on Tibetan pleteau ET. Within the research framework, we are eager to gain new insights into ET spatial and temporal distribution characteristics and teleconnection with water vapor transport, which is essential for understanding the complex interaction within water cycle over Tibetan Plateau.

青藏高原水汽输送路径及水汽分布格局的变化，将深刻影响高原水循环的相互作用，进而引起亚洲季风、东亚大气环流及全球气候变化等一系列的气候响应过程。区域陆表水循环关键性变量对水汽输送将会产生怎样的响应，目前还没有明确的认识。因此，本项目利用再分析气象资料驱动三维拉格朗日粒子后向轨迹模式，并计算不同时间尺度下整层水汽平均输送量。通过模拟和统计分析，得出近十年间青藏高原夏季，前向15天水汽源地和平均水汽输送通量的空间分布状况和变化趋势。再利用多源遥感陆面蒸散发模型，基于风云系列气象卫星可见光和微波辐射计观测数据，反演高原陆表遥感像元尺度的蒸发量，并依据站点通量观测进行有效性验证；最后通过对像元尺度的蒸散发量与水汽通量相关矢分析，进一步阐明高原蒸散发对水汽输送的响应状态。本项目将有助于揭示青藏高原大气水汽输送格局与陆表水循环关键变量的相互作用机理，加深气候变化对青藏高原地—气耦合系统影响的认识。

研究黄河源区干湿演变条件下的水汽输送特征具有重要意义。本文基于“黄河源区玛曲-若尔盖土壤温湿监测网络”自2008年观测以来至2017年的观测资料，通过分析多层土壤湿度异常百分比指数SMAPI，捕捉十年来该地区的干湿演变过程，并利用NCEP FNL(National Centers for Environmental Prediction Final，NECP FNL)再 分析数据资料驱动拉格朗日后向轨迹模式，模拟不同过程的水汽输送粒子（气块）的后向轨迹，从而诊断来到该区域的水汽输送路径以及可能的水汽源区。结果表明，水汽路径可以分为3条：（1）来自印度洋、阿拉伯海的水汽，通过印度半岛、孟加拉湾，从青藏高原西南侧进入；（2）来自太平洋、南海等地的水汽从华东/华南地区登陆中国大陆，途径长江流域，从青藏高原东侧或者南侧进入，也有从青藏高原西侧进入黄的轨迹；（3）来自大西洋、非洲大陆北部和欧洲大陆的水汽，穿过中纬度亚欧大陆，从青藏高原西部或者北部进入。在干旱时期以第三类轨迹为主，湿润时期以第一、二类为主。湿润时期的水汽源地主要分布在 青藏高原上的昆仑山脉附近、喜马拉雅山南麓、孟加拉湾、印度半岛以及四川盆地，云贵高原-南海附近，长江中下游、华东等地，在帕米尔高原和伊朗高原也存在强度较弱的水汽源地；而干旱 时期帕米尔高原、伊朗高原水汽源地的贡献有所加强，青藏高原上的水汽源地偏北，集中在天山山脉-祁连山一带，喜马拉雅山南麓东段的水汽源地减弱，孟加拉湾的水汽源地强度加强，云贵高原-南海附近、长江中下游、华东等地的水汽源地消失。