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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

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

  • 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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