1. An Analysis of the Low-Level Wind Field Over the Ross Ice Shelf, Antarctica Melissa A. Richards (Nigro) John J. Cassano University of Colorado

2. 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 2 Sabrina AWS Photo Courtesy of Shelley Knuth

3. Components of the Low-Level Wind Field Katabatic Winds 3 Figure from Parish and Bromwich (1987) Barrier Winds Figure from Parish et al. (2006) Synoptic Forcing Average Wind Field Role of local topography?

4. Dufek Coast & Prince Olav Mountains

5. 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

6. September 2009 Case Study

8. Synoptic Forcing – Over the RIS BEFORE AFTER

9. Barrier Winds 700 mb WindsSLP10 m Winds

10. Synoptic Forcing – Upper Level Ridge BEFORE AFTER SLP500 mb300 mb

11. September 2009 Case Study

12. 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