Mesoscale cyclone activity over Antarctica during 1991. 2. Near the Antarctic peninsula

A survey of mesoscale cyclogenesis near the Antarctic peninsula has been carried out for 1991 based on digital satellite imagery collected at Palmer Station. Slightly higher cyclonic activity was found over the Bellingshausen Sea sector (BSS) than in the Weddell Sea sector (WSS). Both sides were characterized by a pronounced formation maximum in summer and a minimum in winter. Comma clouds were the dominant vortex type, and their average diameter was around 370 km. Trajectories show that many vortices in the BSS move northeastward toward the Drake Passage, with some of the most well developed moving north-northeastward to the southern tip of South America, bringing severe weather conditions to that area; little systematic motion was noted over the WSS. The fraction of mesoscale cyclones with middle and/or high cloud on the west side of the Antarctic peninsula was much higher than on the east side. These numerous and deep mesoscale cyclones are a consequence of the frequent outbreaks of cold air associated with synoptic-scale cyclones that move cold air northward over the relatively warm Bellingshausen Sea, with convective instability resulting. This happens much less often in the WSS, where low-level baroclinic instability and vortex stretching are the dominant formation mechanisms and air-sea interaction is usually much less vigorous due to the stabilizing influence of the extended sea-ice cover.

[1]  D. Bromwich,et al.  MESOSCALE CYCLONE ACTIVITY NEAR TERRA NOVA BAY AND BYRD GLACIER, ANTARCTICA DURING 1991 , 1996 .

[2]  G. Heinemann.  Mesoscale Vortices in the Weddell Sea Region (Antarctica) , 1990 .

[3]  Duane E. Waliser,et al.  ARC - a source of multisensor satellite data for polar science , 1992 .

[4]  Mark J. Fitch,et al.  Antarctic mesocyclone regimes from satellite and conventional data , 1992 .

[5]  J. Turner,et al.  Summer-season mesoscale cyclones in the bellingshausen-weddell region of the antarctic and links with the synoptic-scale environment , 1994 .

[6]  Günther Heinemann,et al.  A wintertime polar low over the eastern Weddell Sea (Antarctica): A study with AVHRR, TOVS, SSM/I and conventional data , 1996 .

[7]  H. Loon,et al.  Climate of the Upper Air: Southern Hemisphere. Volume 2: Zonal Geostrophic Winds , 1971 .

[8]  D. Bromwich,et al.  Climatological Aspects of Mesoscale Cyclogenesis over the Ross Sea and Ross Ice Shelf Regions of Antarctica , 1994 .

[9]  T. Warner,et al.  On the Mechanism for the, Development of Polar Lows , 1983 .

[10]  K. Tsuboki,et al.  Mesoscale Cyclogenesis in Winter Monsoon Air Streams : Quasi-geostrophic Baroclinic Instability as a , 1992 .

[11]  D. Bromwich,et al.  The Inversion Wind Pattern over West Antarctica , 1986 .

[12]  J. Turner,et al.  Seasonal variability of mesocyclone activity in the Bellingshausen/Weddell region of Antarctica , 1996 .

[13]  Mark J. Fitch,et al.  Synoptic aspects of Antarctic mesocyclones , 1993 .

[14]  D. Bromwich.  Mesoscale Cyclogenesis over the Southwestern Ross Sea Linked to Strong Katabatic Winds , 1991 .

[15]  V. Oliver,et al.  The use of satellite pictures in weather analysis and forecasting , 1966 .

[16]  D. Bromwich,et al.  Mesoscale cyclone activity over Antarctica during 1991: 1. Marie Byrd Land , 1997 .

[17]  J. Turner,et al.  A comparison of Arctic and Antarctic mesoscale vortices , 1993 .

[18]  J. Turner,et al.  A mesoscale vortex over Halley Station, Antarctica , 1993 .