北大西洋爆发性气旋的统计特征

Statistical characteristics of explosive cyclones over the Northern Atlantic

  • 摘要: 利用National Centers for Environmental Prediction(NCEP)提供的Final Analysis(FNL)再分析资料,对2000-2015年冷季(10月至次年4月)北大西洋上的爆发性气旋进行了分析,综合考虑气旋中心位置经向分布特征和海面10 m高风场对爆发性气旋的定义进行了修订。根据气旋中心海表面气压最大加深率的空间分布,发现北大西洋爆发性气旋主要发生在4个区域,即:北美大陆区、西北大西洋区、北大西洋中央区和东北大西洋区。整个北大西洋区爆发性气旋个数随海表面中心气压最大加深率增大而减少,自西向东气旋强度增强,气旋移动路径呈西南-东北向。按气旋强度等级可分为4类:超强(≥ 2.15 Bergeron(Ber))、强(1.75-2.14 Ber)、中(1.45-1.74 Ber)、弱(1.00-1.44 Ber)爆发性气旋。在北大西洋海盆区,自西南向东北爆发性气旋的个数逐渐减少,爆发时长变短。西北大西洋区气旋中心气压加深率最大,爆发时长最长。东北大西洋区加深率最小,爆发时长最短。东北大西洋区爆发性气旋主要发生在12月,北大西洋中央区主要发生在12月-次年3月,西北大西洋区主要发生在1-2月。与海上相比,北美大陆区爆发性气旋发生个数少,强度弱,爆发时长短。

     

    Abstract: Using the Final Analysis (FNL) data from the National Centers for Environmental Prediction (NCEP), we investigate statistical characteristics of explosive cyclones (EC) over the northern Atlantic during the cold season (October to April) from 2000 to 2015. The definition of EC is modified after considering the meridional distribution of EC and the 10 m height wind fields associated with EC. It is found that EC mainly occur in four regions, namely the North America Continent, the Northwest Atlantic, the North-Central Atlantic, and the Northeast Atlantic, respectively, according to the spatial distribution of their maximum deepening rates of central sea level pressure (SLP). Over the whole region, EC decrease with the increase in maximum deepening rate of central SLP, the intensity of EC strengthens from west to east, and tracks of EC are basically in a southwest-northeast direction. EC over the northern Atlantic may be classified into four intensity categories according to their maximum deepening rates, which are super (≥ 2.15 Bergeron (Ber)), strong (1.75-2.14 Ber), moderate (1.45-1.74 Ber) and weak (1.00-1.44 Ber), respectively. Analyses indicate that the number of EC decreases and their duration times of explosive-deepening shorten from southwest to northeast over the northern Atlantic basin. The maximum deepening rate of EC over the Northwest Atlantic region is the largest, and the duration time of explosive-deepening is the longest. Oppositely, the maximum deepening rate of EC over the Northeast Atlantic region is the smallest, and the duration time of explosive-deepening is the shortest. EC over the Northeast Atlantic region, the North-Central Atlantic region, and the Northwest Atlantic region mainly occur in December, from December to March, and from January to February, respectively. Compared with these characteristics over the ocean, EC over the North America Continent are the least in number, the weakest in intensity, and the shortest in duration time of explosive-deepening.

     

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