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ИСТИНА ЦЭМИ РАН |
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Satellite based estimations of cloud shapes and mesocyclones produce realistic picture of mesocyclone activity however they suffer from time-consumtion that characterize manual tracking of mesocyclones from satellite images. To fill the gap in realistic picture of mesocyclone activity in Southern Hemispherewe present the new unique database of mesoscale vortexes (<1000 km in diameter) activity for one winter 2004 over the Southern Ocean. Mesocyclones were derived from AMRC satellite infrared mosaics that cover SH polar regions inside 40 s.h. with 3-hourly time resolution. We manually tracked all mesocyclones from their signature in cloud structures, keeping notes on their diameter, cloud shapes and synoptic situation at the moment of mesoscale cyclogenesis. Based on this data set we demonstrate statistics of mesocyclones lifecycle such as lifetime, diameter, migration speed and distance and spatial distribution of genesis/lysis points and We also focus on phenomena known as polar lows and show that 72% of all mesocyclones during winter of 2004 satisfy criteria and can be considered as polar lows. This database provides unique source of validation material for new tracking algorithms for designed especially for mesocyclones. We also provide an assessment of the representation of mesocyclones in global 3rd generation of reanalyses (NCEP CFSR, ERA INTERIM) and regional high resolution data (self-made WRF hindcast for investigated period). To determine favorable for mesoscale cyclogenesis circulation conditions we constructed composite maps of basic atmospheric fields from reanalysis.