江淮梅雨季亚洲阻塞高压活动统计特征

Statistical characteristics of Asian blocking activity during the Yangtze-Huaihe Meiyu season

  • 摘要: 利用1960—2018年6—7月NCEP/NCAR逐日再分析资料和同期中国国家气象站日降水量资料,对江淮梅雨季亚洲地区阻塞高压活动地理分布、关键区阻塞高压事件活动频次、生命周期以及年际和年代际变化,及其与江淮梅雨异常的关系进行了系统分析。结果表明:(1)近59年江淮梅雨季(6—7月),亚洲阻塞高压事件共计363次,其中心主要分布在乌拉尔山区域(40°—80°E)、贝加尔湖区域(80°—120°E)和鄂霍次克海区域(120°—160°E)3个关键区。(2)3个关键区阻塞高压事件的次数和累计日数由高到低依次为:鄂霍次克海、乌拉尔山和贝加尔湖区域。双阻塞形势以乌拉尔山-鄂霍次克海双阻居多,约占亚洲地区双阻日数的60%。阻塞事件的平均生命周期7 d左右,最长维持时间为13 d。(3)3个关键区总的及分区的阻塞次数和日数都有明显的年际变化并呈增加的趋势,其中线性增加趋势最为明显的是鄂霍次克海区域,与近59年江淮梅雨季的累计雨量增加趋势一致。(4)江淮梅雨季降雨量多寡与阻塞高压活动密切相关,梅雨正(负)异常年鄂霍次克海区域、乌拉尔山-鄂霍次克海双阻日数和次数显著偏多(偏少),而乌拉尔山和贝加尔湖区域的阻塞高压事件与梅雨关系并不显著。(5)江淮梅雨季鄂霍次克海阻塞高压的日数多寡可能与前期海表温度异常信号ENSO有关。

     

    Abstract: The NCEP/NCAR daily analysis data for June and July of 1960—2018 and daily precipitation data collected at national weather stations in China for the same period are used to analyze geographical distribution of blocking activities in Asia, the characteristics of blocking events in key areas, and the relationship between blockings and abnormal Meiyu during the Yangtze-Huaihe Meiyu season. The results show that: (1)In the Yangtze-Huaihe Meiyu seasons (June—July) of the last 59 years, there are a total of 363 blocking events in Asia, and the centers are mainly distributed in three key areas, i.e., the Ural Mountains (40°—80°E), the Lake Baikal (80°—120°E) and the Okhotsk Sea (120°—160°E); (2) the frequency and number of days of blocking events in the three key areas from high to low are the Okhotsk Sea, the Ural Mountains and the Lake Baikal. The double-blocking situation is dominated by the Ural Mountains-Okhotsk Sea double-blocking pattern, which accounts for 60% of the double-blocking days in Asia. The average life cycle of the blocking event is about 7 d, and the longest holding time is 13 d; (3) there are obvious interdecadal changes and increase trends in the blocking frequency and number of days in the three key blocking areas, which are more obvious in the Okhotsk Sea. These changes are consistent with the increase trend of cumulative rainfall in the Yangtze-Huaihe Meiyu seasons of the past 59 years; (4) the amount of rainfall in the Yangtze-Huaihe Meiyu season is closely related to blocking activities. There are significantly more (less) blocking events in the Okhotsk Sea and Ural-Okhotsk in years of positive (negative) Meiyu rainfall anomalies, while the blocking events in the Ural and Baikal regions are not significantly related to Meiyu; (5) in the Yangtze-Huaihe Meiyu season, the number of blocking days in the Okhotsk may be related to the early sea surface temperature anomaly signal of ENSO.

     

/

返回文章
返回