高级搜索

2024年浙江梅雨期降水的典型与非典型时空特征分析

Analysis on typical and atypical spatiotemporal characteristics of Mei-yu precipitation over Zhejiang Province in 2024

  • 摘要: 利用浙江省66个国家气象观测站1973—2024年6—8月逐日降水量观测数据、NCEP/NCAR逐日再分析数据、CIPAS3.1西太副高西段脊线指数数据和ERSSTv5海温月数据,首先分析了2024年梅雨期降水的空间分布特点,然后研究其阶段性特征及其环流和前期海温背景,最后初步探讨了梅雨正常年份的多样性和复杂性。结果表明:(1) 2024年浙江梅雨在统计特征上总体接近常年,6月9日入梅、7月4日出梅,梅雨量和梅雨强度指数均处于正常水平。但降水时空分布呈非典型特征,整体表现为“西多东少”,降水强度及中雨以上降水日数偏多,同时部分非梅雨区出现显著异常降水,非梅雨量接近梅雨量的90%。(2) 2024年浙江梅雨过程具有明显阶段性特征。6月9—18日强降水主要出现在浙西南地区,6月19日以后转移至浙西北地区。6月19日前后为关键转折时期,东亚夏季风增强、西太平洋副热带高压发展并北跳以及南亚高压调整等多系统协同作用,导致浙江降水增强并出现降水中心北移。海温背景上,前冬春季厄尔尼诺及多海域海温异常通过增强水汽输送并抑制冷空气南下共同影响初夏环流,其相互制约可能使2024年浙江梅雨强度总体接近常年。(3)浙江9个梅雨正常年份中,并不一定表现为典型的“浙中北梅雨”降水格局,且不同年份降水空间分布差异较大,非梅雨区亦可能出现强降水,“梅雨量正常”并不等同于“降水空间分布正常”。

     

    Abstract: This study analyzed the daily precipitation observations from 66 national meteorological stations in Zhejiang Province for June–August during 1973–2024, daily NCEP/NCAR reanalysis data, the CIPAS3.1 western ridge index of the Western Pacific Subtropical High (WPSH), and ERSSTv5 monthly sea surface temperature (SST) data, this study first analyzes the spatial distribution characteristics of precipitation during the Meiyu period in 2024. It then examines the stage-wise evolution of precipitation and its associated circulation patterns and preceding SST background, and finally provides a preliminary discussion on the diversity and complexity of Meiyu conditions in years with near-normal rainfall totals. The results are as follows. (1) The overall statistical characteristics of the 2024 Zhejiang Meiyu were close to the climatological mean, with the onset on 9 June and withdrawal on 4 July. Both the total Meiyu rainfall and the Meiyu intensity index were within the normal range. However, the spatiotemporal distribution of precipitation exhibited atypical features, with an overall pattern of “more rainfall in the west and less in the east.” Precipitation intensity and the number of days with moderate rainfall or above were higher than normal, while some non-Meiyu regions experienced pronounced anomalous rainfall, with non-Meiyu rainfall reaching nearly 90% of the Meiyu rainfall. (2) The Meiyu process in 2024 showed clear stage characteristics. From 9 to 18 June, heavy precipitation mainly occurred in southwestern Zhejiang, while after 19 June it shifted to northwestern Zhejiang. Around 19 June represented a key transition period, during which the strengthening of the East Asian summer monsoon, the intensification and northward shift of the Western Pacific Subtropical High, and the adjustment of the South Asian High acted in concert, leading to enhanced precipitation and a northward shift of the rainfall center over Zhejiang. In terms of SST background, the El Niño event during the preceding winter–spring and SST anomalies in multiple ocean basins jointly influenced the early-summer circulation by enhancing moisture transport while suppressing the southward intrusion of cold air. The interaction between these factors likely contributed to the overall near-normal Meiyu intensity in Zhejiang in 2024. (3) Among the nine near-normal Meiyu years in Zhejiang, precipitation does not necessarily exhibit the typical “central–northern Zhejiang Meiyu” rainfall pattern. The spatial distribution of rainfall varies considerably among different years, and heavy rainfall may also occur in non-Meiyu regions. Therefore, “near-normal Meiyu rainfall” does not necessarily imply a “normal spatial distribution of precipitation.”

     

/

返回文章
返回