Pacific and atlantic ‘bomb‐like’ deepenings in mature phase: A comparative study

• Published in: Quarterly Journal of the Royal Meteorological Society
• Main Authors: Lemaǐtre, Y., Protat, A., Bouniol, D.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1999
• Subjects: Greenland; Pacific; Slot The
• Online Access: http://dx.doi.org/10.1002/qj.49712556119; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fqj.49712556119; https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.49712556119

Abstract The mesoscale dynamics of a secondary cyclone sampled during the field phase of the Fronts and Atlantic Storm‐Track Experiment (FASTEX) are documented using airborne Doppler radar data. the high quality of the mesoscale airborne Doppler dataset collected within this secondary cyclone is highlighted. This study demonstrates, however, the need to combine in the near future airborne Doppler radar and dropsonde measurements, in order to access multiscale processes involved in the mature stage of this FASTEX cyclone both in clear‐air and in precipitating regions. the studied secondary cyclone developed on the trailing cold front of a parent low situated over Greenland, and underwent the most explosive deepening (roughly −54 mb in 24 hours) sampled in the multiscale sampling area during FASTEX. the main flows responsible for the mesoscale organization of the cyclone are: a warm airflow emerging from the base of the synoptic warm conveyor belt that generates the most active part of the cloud head; a dry intrusion approaching in the dry slot the cyclone centre; a cold conveyor belt that contributes to the upward mass transport towards the upper part of the polar‐front cloud band; and a cold northerly flow in the western part of the cloud head, which tends to wrap around the low centre and is likely to release convective instability through air‐sea interactions. This study also documents a slight shift in position between the high vertical‐vorticity core associated with the active part of the cloud head and the location of the pressure minimum. The detailed three‐dimensional structure of this Atlantic secondary cyclone is also compared with that gathered within another ‘bomb‐like’ deepening (defined as more than a 24 mb surface pressure drop in 24 hours) observed over the Pacific ocean during the Coastal Observation and Simulation with Topography (COAST) experiment. Some similarities are found. the main differences appear to be linked to the warm seclusion that is exclusive to the studied Pacific cyclone. More ...