Abstract
Mesoscale cyclones (or mesocyclones) play an important role in the weather and climate of the Southern Hemisphere (SH) mid-to-high latitudes. However, the relatively small size and short lifetime of these systems, combined with the lack of available conventional data in this region, means that we have a poor understanding of their climatological characteristics. In this study, the University of Melbourne cyclone finding algorithm was applied to relatively high resolution scatterometer-derived surface pressure fields in order to produce a decade-long (1999-2008) climatology of mesocyclone activity over the Southern Ocean. The frequency of mesocyclone activity was found to be highest just to the north of the sea-ice zone, reaching a maximum over the Amundsen and Bellingshausen Seas (ABS) and off the coast of Wilkes Land, while the southern Indian Ocean was associated with systems of the largest depth, intensity and mean surface fluxes of momentum and mechanical energy. Maximum wind speed data indicated that SH polar lows may be more frequent than the current literature suggests, while strong positive trends identified in mesocyclone frequency over the ABS may represent a contributing factor to the rapid warming observed in that region over recent years. Partial correlation analyses indicated a link between mesocyclone frequency and the Southern Annular Mode.