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陈桂万, 龙雨青, 陈雄, 等. 2023. 海洋性大陆地区季节内对流活动对中国东南地区冬季降水的影响[J]. 气候与环境研究, 28(2): 143−159. doi: 10.3878/j.issn.1006-9585.2021.21156
引用本文: 陈桂万, 龙雨青, 陈雄, 等. 2023. 海洋性大陆地区季节内对流活动对中国东南地区冬季降水的影响[J]. 气候与环境研究, 28(2): 143−159. doi: 10.3878/j.issn.1006-9585.2021.21156
CHEN Guiwan, LONG Yuqing, CHEN Xiong, et al. 2023. Impacts of Intraseasonal Convection Activity over Maritime Continent on the Boreal Winter Precipitation over Southeastern China [J]. Climatic and Environmental Research (in Chinese), 28 (2): 143−159. doi: 10.3878/j.issn.1006-9585.2021.21156
Citation: CHEN Guiwan, LONG Yuqing, CHEN Xiong, et al. 2023. Impacts of Intraseasonal Convection Activity over Maritime Continent on the Boreal Winter Precipitation over Southeastern China [J]. Climatic and Environmental Research (in Chinese), 28 (2): 143−159. doi: 10.3878/j.issn.1006-9585.2021.21156

海洋性大陆地区季节内对流活动对中国东南地区冬季降水的影响

Impacts of Intraseasonal Convection Activity over Maritime Continent on the Boreal Winter Precipitation over Southeastern China

  • 摘要: 分析了海洋性大陆地区季节内对流活动对北半球冬季中国东南地区降水的影响。根据这些对流活动是否具有东传特征,进一步将它们分为连续东传的MJO(Madden-Julian Oscillation)对流事件和准静止的非MJO对流事件。结果表明,这两类季节内对流活动对中国降水的影响存在明显差异。MJO对流对中国降水影响的空间范围较大,并且降水在MJO东传过程中呈现连续南传特征;非MJO对流的影响范围较小,并且其影响的关键区域随时间由北向南跳变。当对流在海洋性大陆地区处于活跃(抑制)位相时,MJO对流会导致中国东南地区降水呈现南正北负(南负北正)的偶极型分布,而非MJO对流仅仅会导致广东和福建一带降水偏少(偏多)。当对流在海洋性大陆地区由抑制(活跃)位相向活跃(抑制)位相转换时,MJO对流会引起中国东南大部分地区降水偏多(偏少),非MJO对流则引起江西北部、福建西北和浙江西部一带降水偏少(偏多)。水汽通量诊断结果表明,两类对流事件影响中国降水都主要受到季节内尺度风场异常的调控。具体来说,季节内尺度上低层经向风的差异,进而导致其经向梯度对水汽的输送存在明显差异,最终导致两类不同的季节内对流对中国东南地区降水的影响存在差异。

     

    Abstract: This study assessed the effects of intraseasonal convection over the Maritime Continent on the boreal winter precipitation over Southeast China. The intraseasonal convection events were further classified into MJO (Madden-Julian Oscillation) events with continuous eastward propagation and non-MJO events with stationary oscillation. The outcomes suggest that the effects of the MJO and non-MJO events on the precipitation over Southeast China are quite distinct. The precipitation anomalies linked to MJO over Southeast China have a wider spatial range and demonstrate continuous southward propagation as the MJO propagates eastward, while the range of precipitation anomalies linked to the non-MJO is narrower, and the precipitation center shifts southward over time. When the convection is active (inactive) over the Maritime Continent, the MJO-induced precipitation anomalies over Southeast China reveal a northward positive-negative (negative-positive) dipolar distribution, while the non-MJO-induced precipitation anomalies demonstrate a negative (positive) pattern over Guangdong and Fujian. When the convection is transformed from the suppressed (active) to the active (suppressed) phase over the Maritime Continent, the MJO-induced precipitation anomalies are positive (negative) over Southeast China, while the non-MJO-induced precipitation anomalies indicate a negative (positive) pattern over northern Jiangxi, northwestern Fujian, and western Zhejiang. The moisture flux diagnosis indicates that both the MJO and non-MJO convection-induced precipitation anomalies over Southeast China are controlled by intraseasonal low-level circulations. Exclusively, the low-level meridional winds influenced by MJO and non-MJO convection are distinct over the sub-tropical region; this results in different gradients of the meridional winds on the moisture, which further leads to various moisture transport processes that identify the precipitation anomalies over Southeast China controlled by two types of intraseasonal convection events.

     

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