基于LMDZ模型的西南地区水汽来源及水汽再循环率的分析

Analysis of Water Vapor Source and Contribution of Recycled Moisture to Precipitation in Southwest China Based on LMDZ Model

研究基于LMDZ模型对我国西南地区9个站点的同位素数据进行空间插值,利用同位素混合模型对不同来源水汽对降水的贡献率进行时空分析。结果表明,我国西南地区外来水汽对降水的贡献率除部分站点外,均在90%以上;其次为植物蒸腾水汽,占比为0.3%~21.3%,地表蒸发水汽对降水贡献率最小,介于0.1%~8.1%之间,同时外来水汽对降水贡献率夏季大于冬季,而地表蒸发水汽和植物蒸腾水汽对降水的贡献率冬季略大于夏季。水汽再循环率呈现空间差异,四川盆地及周围山地地表蒸发水汽与植物蒸腾水汽略高于青藏高原及云贵高原一带。结合美国国家大气研究中心所提供的气象资料,采用MeteoInfo软件对我国西南地区各站点进行近10年(1998~2007)的后向轨迹追踪,并对其进行聚类分析得出四川省两站点和重庆站点在夏季近源局地蒸发水汽占比高达50%,贵阳夏季有28.95%的水汽为近源局地蒸发形成,其余站点夏季水汽来源大部分来自于阿拉伯海、孟加拉湾和印度洋水汽,还有一部分来自于西风带的水汽和东南季风带来的西太平洋的水汽,然而冬季水汽均来自于西风带水汽。

The isotopic data of 9 stations in southwest China was interpolated with the LMDZ model,and the contribution of different sources of water vapor to precipitation was estimated using the isotope mixing model.The results showed that the contribution of advection moisture to precipitation in southwest China,with exception at some sites,was more than 90%,then followed by plant transpiration water vapor and surface evaporation water vapor,which accounted for 0.3%-21.3%and 0.1%-8.1%of total precipitation,respectively.At the same time,the contribution of advection moisture to precipitation in summer was greater than that in winter,while the contribution of surface evaporation water vapor and plant transpiration water vapor to precipitation was slightly greater in winter than summer.The water vapor recirculation rate presented a spatial difference.The surface evaporated water vapor and plant water vapor in the Sichuan Basin and surrounding mountains were slightly higher than that in the Qinghai-Tibet Plateau and the Yunnan-Guizhou Plateau.MeteoInfo software combined with the meteorological data provided by the National Center for Atmospheric Research was run to track the backward trajectories of stations in southwest China for nearly ten years(1998-2007)and the cluster analysis was performed.It indicated that,in summer,higher contributions of near-source local evaporation was observed at some stations,e.g.,two stations in Sichuan Province and Chongqing with contribution over 50%and station in Guiyang with contribution of 28.95%.The rest station’s summer water vapor mostly comes from the Arabian Sea,Bay of Bengal and Indian Ocean.There was also a part of the water vapor coming from the westerly zone and the western Pacific brought by the southeast monsoon.However,the source of water vapor in winter dominantly came from the westerly zone.