夏季怒江流域水汽输送多支特征及对降水影响

基于高空间分辨率0.25°的ERA-Interim再分析资料、TRMM 3B43 Version7数据、气象站点实测数据等多源数据,本文采用一种新的流域边界水汽通量概化和提取方法,揭示了夏季怒江流域水汽输送多支特征,并分析了其对降水时空分异的影响。研究表明,在高黎贡山南部、北部,伯舒拉岭北部及念青唐古拉山中部,有4支区域性水汽输送高值区,多年平均输送通量分别达102.6 kg/(m·s)、66.3 kg/(m·s)、39.7 kg/(m·s)和41.3 kg/(m·s)。多支水汽输送不仅深刻影响流域水汽输送格局,而且对降水时空分异也有不同程度影响。年际变化上,中下游横断山区水汽输送对降水的影响较小,上游青藏高原区影响较大,尤其以那曲—比如—索县一带影响最为显著。空间分布上,流域降水与水汽输送通量呈显著正相关,受多支水汽输送影响形成多个区域性多雨带。

Multiple branches of water vapor transport over the Nujiang River Basin in summer and its impact on precipitation

Water vapor transport is a key factor in the transformation of atmospheric water resources to terrestrial water resources. In order to reveal the characteristics of water vapor transport and its influence on precipitation over the Nujiang River basin, high spatial resolution (0.25°) ERA-Interim reanalysis data, TRMM 3B43 Version7 data, meteorological station measured data and SRTM Version4.1 DEM data were used, and a new method to generalize and extract water vapor transport data along the watershed boundary was adopted. Through analysis and research, the multiple branches water vapor transports over the Nujiang River Basin in summer were detected, and their effects on the spatiotemporal distribution of precipitation were analyzed. The research shows that there are four regional high-value areas of water vapor transport on the western boundary of the watershed, which are located in the southern and northern parts of Gaoligong Mountain, the northern part of Boshula Mountain, and the middle of Nyenchen Tanglha Mountains, with the annual average water vapor flux being 102.6 kg/(m·s), 66.3 kg/(m·s), 39.7 kg/(m·s), and 41.3 kg/(m·s), respectively. Multiple branches water vapor transport affects not only the water vapor transport in different areas of the basin, but also the spatiotemporal characteristics of precipitation. In terms of interannual variation, the influence of water vapor transport on precipitation is weaker in the middle and downstream area (Hengduan Mountains), while it is greater in the upstream area (Qinghai-Tibet Plateau), especially in the Nagqu-Biru-Suoxian area. In terms of spatial distribution, annual precipitation in the basin is significantly positively correlated with water vapor flux and negatively correlated with water vapor flux divergence. Because of multiple branches of water vapor transport, four regional rainy areas are formed by the west side of the basin.