an analysis of the low-level wind field over the ross ice shelf, antarctica melissa a. richards...
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An Analysis of the Low-Level Wind Field Over the Ross Ice Shelf, Antarctica
Melissa A. Richards (Nigro)John J. Cassano
University of Colorado
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Agenda
• Components of the Low-Level Wind Field Over the Ross Ice Shelf
• Strong Wind Speeds Near the Dufek Coast & the Prince Olav Mountains
• Case Study – September 2009
• Conclusion & Future Work Sabrina AWSPhoto Courtesy of Shelley Knuth
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Components of the Low-Level Wind Field
Katabatic Winds
Figure from Parish and Bromwich (1987)Barrier Winds
Figure from Parish et al. (2006)
Synoptic Forcing
Average Wind Field
Role of local topography?
Dufek Coast & Prince Olav Mountains
Dufek Coast & Prince Olav Mountains
Previous studies– Seefeldt and Cassano [2008]
• Mountains protrude into low-level jet resulting in a tip jet
– Steinhoff et al. [2009] • Flow is primarily around the mountains not over resulting in a
“knob” flow
– Each study mentions the need for additional analysis of the dynamics in this region to determine the mechanisms responsible for the strong winds in this region
September 2009 Case Study
September 2009 Case Study
Synoptic Forcing – Over the RIS
BEFORE
AFTER
Barrier Winds
700 mb Winds SLP10 m Winds
Synoptic Forcing – Upper Level Ridge
BEFORE
AFTER
SLP 500 mb 300 mb
September 2009 Case Study
Conclusion & Future Steps
CONCLUSIONS:• The interaction of two or more forcing mechanisms can result in
areas of very strong winds• Forcing for barrier wind development not seen at the 10 meter
level, but evident at 700 mb where observations do not currently exist
• The forcing mechanisms throughout the jet are spatially different
FUTURE STEPS:• Understand the dynamics that cause the jet to accelerate in the
location of the Sabrina AWS• Determine how often these events occur and if the same forcing
mechanisms are present
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