Southern Ocean mesocyclones and polar lows from manually tracked satellite mosaics

A new reference dataset of mesocyclone activity over the Southern Ocean has been developed from the manual analysis of high resolution infrared satellite mosaics for winter 2004. Of the total 1735 mesocyclones which were identified and analyzed about three quarters were classified as being ‘polar lows’ (i.e. intense systems; see Rasmussen and Turner 2003). The dataset includes mesocyclone track, size, associated cloud vortex type and background synoptic conditions. Maxima in track density were observed over the Bellingshausen Sea and around East Antarctica and are highly correlated with cyclogenesis regions. A comparison against QuikSCAT and reanalyses wind characteristics shows that the reanalyses, while capturing mesocyclone events, tend to considerably underestimate their wind speed (by up to 10 ms-1). This mesocyclone dataset is available as a reference for further analysis of mesocyclones and for the evaluation and development of cyclone-tracking algorithms.