Objective identification research on cold vortex and mid-summer rainy periods in Northeast China

• 作者: 封泰晨 房一禾 龚志强
• 来源期刊: 中国物理B（英文版）
• 关键词: Northeast China cold vortex rainy period mid-summer rain period objective identification method
• 年，卷（期）: 2015,（4）
• 页码范围: 049204-1-049204-10
• 页数: 1页
• 语种: 英文
• DOI: 10.1088/1674-1056/24/4/049204

摘要

Considering the differences between the Northeast China Cold Vortex (CV) and the Mid-Summer (MS) rainy period and their corresponding atmospheric circulations are comprehensively analyzed, and the objective identification methods of defining the annual beginning and ending dates of Northeast China CV and MS rainy periods are developed respectively. The annual beginning date of the CV (MS) rainy period is as follows. In a period from April to August, if daily regional mean precipitation ryi is larger than yearly regional mean precipitation R (or 2R) on a certain day, the station precipitation rs is larger than the station yearly mean precipitation hri (or 2hri) in at least 50%of stations in Northeast China, and this condition is satisfied in the following 2 (7) days, then this date is defined as the beginning date of the CV (MS) rainy period. While the definition of the ending date of the MS rainy period shows the opposite process to its beginning date. With this objective identification method, the multi-year average (1981–2010) beginning date of the CV rainy period is May 3, the beginning date of the MS rainy period is June 27, the ending day of the CV rainy period is defined as the day before the beginning date of the MS rainy period, and the ending date of the MS rainy period is August 29. Meanwhile, corresponding anomaly analysis at a 500-hPa geopotential height, 850-hPa wind, Omega and relative humidity fields all show that the definitions of the average beginning and ending dates of the CV and MS rainy periods have a certain circulation meaning. Furthermore, the daily evolution of the CV index, meridional and zonal wind index, etc. all show that these objectively defined beginning and ending dates of the CV and MS rainy periods have climate significance.