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由丽蓉, 姜继兰, 陈笑晨, 等. 2022. 梅雨期长江中下游地区湿位涡的特征及其与青藏高原的联系[J]. 大气科学, 46(6): 1505−1522. doi: 10.3878/j.issn.1006-9895.2207.21266
引用本文: 由丽蓉, 姜继兰, 陈笑晨, 等. 2022. 梅雨期长江中下游地区湿位涡的特征及其与青藏高原的联系[J]. 大气科学, 46(6): 1505−1522. doi: 10.3878/j.issn.1006-9895.2207.21266
YOU Lirong, JIANG Jilan, CHEN Xiaochen, et al. 2022. Characteristics of Moist Potential Vorticity over the Middle and Lower Reaches of the Yangtze River during the Meiyu Season and Its Relationship with the Tibetan Plateau [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 46(6): 1505−1522. doi: 10.3878/j.issn.1006-9895.2207.21266
Citation: YOU Lirong, JIANG Jilan, CHEN Xiaochen, et al. 2022. Characteristics of Moist Potential Vorticity over the Middle and Lower Reaches of the Yangtze River during the Meiyu Season and Its Relationship with the Tibetan Plateau [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 46(6): 1505−1522. doi: 10.3878/j.issn.1006-9895.2207.21266

梅雨期长江中下游地区湿位涡的特征及其与青藏高原的联系

Characteristics of Moist Potential Vorticity over the Middle and Lower Reaches of the Yangtze River during the Meiyu Season and Its Relationship with the Tibetan Plateau

  • 摘要: 本文基于欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts, 简称ECMWF)提供的ERA-Interim再分析数据集和FGOALS-f3-L海气耦合模式,分析了1980~2017年梅雨期长江中下游地区对流层大气湿位涡(MPV)的分布特征及其与青藏高原的联系。研究发现,梅雨期湿等熵面在长江中下游地区呈自下而上向北倾斜的分布特征,湿位涡正压项(MPV1)和斜压项(MPV2)的大值带均沿倾斜的湿等熵面分布在梅雨区上空,且随雨带的北移而北移。对流层中层MPV1和MPV2大值带均分布在梅雨雨带的北侧,而对流层低层MPV2负值带与梅雨雨带近乎重合。这主要是由于入梅前后MPV2的分布结构满足倾斜涡度发展的必要条件,有利于暖湿空气沿湿等熵面上滑,从而导致暖湿空气的垂直涡度显著增强,造成梅雨降水。进一步分析发现MPV2负值带西起青藏高原向东经过江淮地区一直延伸到西北太平洋地区。数值试验结果表明青藏高原大地形条件对MPV2负值带的形成有重要影响,当去掉高原地形时,长江中下游地区的MPV2负值带显著减弱甚至消失。

     

    Abstract: The ERA-Interim reanalysis data provided by the European Center for Medium-Range Weather Forecasts and the FGOALS-f3-L coupled model were used to analyze the characteristics of the moist potential vorticity (MPV) over the middle and lower reaches of the Yangtze River during the Meiyu period from 1980 to 2017 and their connection to the Tibetan Plateau. The moist isentropic surfaces are found to tilt northward with increasing height over the Meiyu area. The belt of the barotropic term (MPV1) and baroclinic term (MPV2) of the MPV lie along the sloping moist isentropic surfaces, which move northward when the rain belt moves northward. MPV1 and MPV2 are located to the north of the Meiyu rain belt in the middle troposphere. However, in the lower troposphere, the negative value belt of MPV2 corresponds better to the Meiyu rain belt. This better correspondence is mainly due to the distribution of MPV2 satisfying the necessary condition of the development of slantwise vorticity, which is conducive to substantial development of the vertical vorticity of the upsliding warm and wet air, resulting in the development of precipitation. Further analysis reveals that the MPV2 belt over the Meiyu area starts from the Tibetan Plateau in the west and extends eastward to the Northwest Pacific. The FGOALS-f3-L output without Tibetan Plateau topography indicates that the Tibetan Plateau has an important influence on the distribution of MPV2 downstream. In the no Tibetan–Iranian Plateau simulations, the negative value belt of MPV2 is substantially weakened and even disappears along the Yangtze River.

     

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