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.