Extratropical cyclones are defined as "explosive" when their deepening rate is maintained at 1 hPa h-1 during a 24-h period. Those systems are important over the South American continent due to their severe socio-economic impacts. This study presents a climatology of explosive cyclones over the cyclogenetic area of South America using NCEP-NCAR re-analysis data from 1957 to 2010. The deepening rate of an individual cyclone was classified with respect to their average latitude. Six-hourly storm attributes such as frequency, genesis, tracks, and deepening rates were analyzed. As a second step, their depth, central pressure, and radius were meaningfully compared with the climatological values obtained from non-explosive cyclones. Horizontal wind fields were compared through a co-moving coordinate system consisting of a 30° lat x 30° lon domain. It was found that the trajectory of most systems started over the ocean and that no explosive cyclones were found to occur at north of 27 °S. This study also highlights that, on average, explosive cyclones are 5.1 hPa deeper, have a radius 0.41°lat. larger, and a central pressure 15.5 hPa lower than non-explosive cyclones. In addition, the data suggested that explosive cyclones were associated with wind speeds that were on average 60 % stronger than non-explosive cyclones.
Explosive Cyclones; South America; Frequency; Tracks
