2015年西北太平洋台风季提早展开:2015/16超级厄尔尼诺的影响
投稿时间: 2016-07-18  最后修改时间: 2016-07-18  点此下载全文
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作者单位E-mail
钱伊恬 南京信息工程大学 ddyitian@163.com 
徐邦琪 南京信息工程大学 pangchi@nuist.edu.cn 
基金项目:国家自然科学基金项目(面上项目,重点项目,重大项目);国家重点基础研究发展计划(973计划)
中文摘要:每年六月至十月为西北太平洋的台风季,长期气候(1979-2015)平均而言,台风季开始前的一月至五月平均只有2.8个热带风暴(tropical storms,TS)生成,其中1.4个可发展增强为台风(typhoons)。然而,2015年1-5月西北太平洋上异常出现了7个TS,其中有5个发展成台风,亦即2015年的台风季提前展开。本研究发现,2015年初异常活跃的台风活动与2015/2016年超级厄尔尼诺事件于西北太平洋上引发的海气状态异常有关。通过对大尺度环境场和台风潜在生成指数(GPI)的诊断分析发现,动力因子(低层涡度、垂直速度)和热力因子(与海表面温度、大气温度有关的潜在强度、中低层大气相对湿度)均对2015年1-5月台风的发生有正贡献,其中涡度项的贡献最大、相对湿度贡献次之,前者可能与赤道太平洋暖海温引发的罗斯贝波响应有关,而后者主要来自于异常的Walker环流上升距平平流暖池区季节平均的低层水汽。除了大尺度海气状态的影响外,3-10天天气尺度扰动和10-90天季节内振荡在2015年1-5月也异常活跃,有利热带低压/台风的生成与发展。
中文关键词:2015超级厄尔尼诺,台风活动,GPI,高、低频扰动
 
Early Onset of Typhoon Season over the Western North Pacific in 2015: The Influence of 2015/16 Super El Ni駉
Abstract:Typhoons season over the western North Pacific (WNP) is generally from June to October. Climatologically (1979-2015), there are only 2.8 tropical storms (TS) generated during January to May before the onset of typhoon season. Among them, about 1.4 TS systems may develop into a typhoon system. However, seven (five) TS (typhoon) systems occurred over the WNP January to May in 2015, suggesting that the typhoon season in 2015 tends to start earlier. Our study found that the unusual growth of TS activity in early 2015 is related to the anomalous air-sea conditions of 2015/16 super El Ni駉 event. The diagnostic results of large-scale environmental fields and typhoons’ genesis potential index (GPI) indicate that dynamic (low-level vorticity and vertical velocity) and thermodynamic (potential intense related to sea surface and air temperature and atmospheric relative humidity in lower to middle levels) factors both contribute positively to the increases in typhoon genesis during January to May in 2015. The low-level vorticity anomaly shows the largest contribution while the enhanced relative humidity is the secondary contributor. The former may be related to the Rossby wave response to the warm sea temperature in tropical Pacific; the latter is due to advection of low-level seasonal mean moisture in the warm pool by the anomalous ascending motion of Walker circulation. Apart from the influence of large-scale air-sea conditions, 3-10-day synoptic-scale disturbances and 10-90-day intraseasonal oscillation are also enhanced during January to May in 2015, favoring the genesis and development of tropical depression/typhoon systems.
keywords:2015 super El Ni駉, typhoon activity, GPI, high- and low-frequency disturbances
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