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CN 11-1768/O4

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2016年梅雨持续性强降水期间大气环流稳定分量研究
作者:
作者单位:

1.天津市津南区气象局;2.国家气候中心;3.天津市气候中心

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基金项目:

国家重点基础研究发展计划,国家自然科学基金


Study on the stable components of atmospheric circulation during the continuous heavy rainfall of Meiyu in 2016
Author:
Affiliation:

1.National Climate Center,Beijing;2.Tianjin Climate Center,Tianjin

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    摘要:

    梅雨降水具有显著的阶段变化特征,研究持续强降水期间的关键环流稳定分量,对于分析和预测梅雨降水具有重要意义。利用NCEP-DOE1979~2016年逐日再分析资料,对2016年梅雨持续强降水期间位势高度场、风场和相对湿度场进行分析,提取环流系统的关键稳定分量,并对其空间结构、演变特征及更长时间尺度的背景形势进行分析,为梅雨区阶段性强降水的延伸期预报提供依据和参考。研究发现:(1)在位势高度场稳定分量中存在的“三极子”分布形势,是维持2016年梅雨持续强降水的关键系统。“三极子”分别对应着乌拉尔山阻塞高压、鄂霍茨克海阻塞高压以及偏东偏强的南亚高压和偏西偏强的副热带高压。这种配置结构有利于冷暖空气在梅雨区交汇形成持续性强降水。(2)在中高纬度两个正“极子”之间,是相对深厚的负距平区,有利于建立强冷空气的向南输送通道,同时相对湿度场稳定分量表明北支气流的水汽输送和汇聚作用对梅雨区持续降水起到非常重要的作用。(3)中低纬度的正距平区域呈纬向带状分布,且主要存在于对流层中高层,但在梅雨区东西两侧各有一个正距平下沉支,它们共同加强了梅雨区南侧暖湿气流的汇聚输送作用。(4)通过对稳定分量的演变分析发现,“三极子”系统的建立和演化与梅雨区降水强弱的阶段变化密切相关。(5)更长时间尺度(60天)环流稳定分量为持续强降水时段的“三极子”关键稳定分量提供了重要的环流背景。

    Abstract:

    Meiyu precipitation has significant stage changes. It is important to study the key circulation stable components that lead to continuous heavy rainfall for the analysis and prediction of Meiyu precipitation. Using NCEP/DOE Reanalysis II data from 1979 to 2016, the potential height field, wind field and relative humidity field during the Meiyu period in 2016 were analyzed, the key stable components of the circulation system were extracted, the spatial structure, evolution characteristics and the background situation of longer time scale were analyzed, which provided the basis for the extended period forecast of the periodic heavy rainfall in Meiyu area Reference resources. The results suggest that: (1) The distribution of "three poles" in the stable components of the geopotential height field is the key system to maintain the continuous heavy rainfall in Meiyu area in 2016. The "three poles" correspond to the Ural Mountains blocking high, the Okhotsk Sea blocking high, the Southeast Asia high and the West subtropical high. This configuration structure is conducive to the convergence of warm and cold air in Meiyu area to form persistent heavy rainfall. (2) In the middle and high latitudes, there is a relatively deep negative anomaly between the two deep positive anomaly areas. On the one hand, it is conducive to the South transportation of cold air. On the other hand, the stable component of relative humidity field indicates that the water vapor transportation and convergence of the northern branch of the air flow play an important role in the continuous precipitation of Meiyu area. (3) The positive anomaly area in the middle and low latitudes is zonal in the east-west direction, and mainly exists in the middle and high troposphere, but there is a positive area on the East-West side of the Meiyu area, which continues down to the lower level, and they together strengthen the convergence and transportation of warm and humid air flow in the south of the Meiyu area. (4) Through the analysis of the evolution of the stable component, it is shown that the establishment and evolution of the "three pole" system lead to the precipitation in Meiyu area showing different stage characteristics.(5) The longer time scale (60 days) circulation stable components provides an important circulation background for the key stable components of the "three pole" in the period of continuous heavy rainfall.

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  • 收稿日期:2019-05-29
  • 最后修改日期:2020-06-05
  • 录用日期:2020-06-22
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