周口秋季连阴雨天气气候特征

在借鉴国内外学者研究方法和经验的基础上,基于NCEP再分析资料和常规天气图等资料,对周口1961～2011年的降水资料进行统计对比分析,找出秋季连阴雨的规律,并对周口秋季连阴雨过程进行大气环流特征分析。结果表明,周口市秋季连阴雨平均1.6年一遇,7 d以上的连阴雨平均约0.7年一遇,≥10 d的长连阴雨平均5年一遇,7 d以上的连阴雨及≥10 d的长连阴雨均是9月份出现最多。秋季连阴雨20世纪70、80年代出现较多,平均为一年两遇;20世纪90年代和21世纪以来大于10 d的长连阴雨天气发生较多,占50%。秋季连阴雨过程雨量在30～50 mm的较多,其次是≥50 mm;过程雨量≥100 mm的主要出现在20世纪80年代和21世纪以来。秋季连阴雨是中高纬度西风带系统和中低纬度副热带系统共同作用形成的;中高纬度系统大致分双阻低压型、单阻低压型、平直环流型、两槽一脊偏北型4种类型。

Characteristics of Autumn Overcast and Rainy Weather in Zhoukou

Based on the research methods and experiences both at home and abroad,the precipitation data in Zhoukou during 1961-2011 was statistically analyzed with the NCEP reanalysis data and conventional weather map,the laws of autumn overcast and rainy weather were found out and the atmospheric circulation features of the autumn overcast and rainy weather were analyzed.As indicated by the results,the continuous rainy weather in autumn in Zhoukou City appeared with an average frequency of 1.6 years,the continuous rainy weather for over seven days had a frequency of 0.7 year,and the continuous rainy weather for over ten days showed a frequency of five years,both were the most in September.The autumn rainy weather appeared mostly in 1970s and 80s,two times a year;the continuous rainy weather for over 10 days appeared frequently since 1990s and 21st century,accounting for about 50%.The rainfall amount of autumn continuous rainy weather was generally about 30-50 mm,then followed by ≥50 mm,the rainfall amount ≥100 mm mainly appeared in 1980s and since 21st century.The autumn continuous rainy weather was co-influenced by middle-high latitude westerly wind system and middle-high subtropical system,and the middle-high latitude systems were mainly divided into four types,including double-resistance low-voltage type,single-resistance low-voltage type,straight circulation type and two troughs and one ridge north type.