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Cassie Stearns Mark Fahnestock, Advisor Research and Discover UNH June 6 - August 10, 2005

The Way the Wind Blows: Emissive thermal imaging of katabatic winds and related features on the East Antarctic Plateau. Cassie Stearns Mark Fahnestock, Advisor Research and Discover UNH June 6 - August 10, 2005. What we Know.

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Cassie Stearns Mark Fahnestock, Advisor Research and Discover UNH June 6 - August 10, 2005

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  1. The Way the Wind Blows:Emissive thermal imaging of katabatic winds and related features on the East Antarctic Plateau Cassie Stearns Mark Fahnestock, Advisor Research and Discover UNH June 6 - August 10, 2005

  2. What we Know • Many surface features in the interior of Antarctica are formed by persistent winds that are strongest in winter. • There are limited observations of conditions on the plateau due to remoteness and lack of sunlight. What we Want to Know • How can thermal imagery improve our understanding of conditions on the East Antarctic Plateau?

  3. South Pole Vostok Ross Ice Shelf MODIS Aqua and Terra visible band composite surface map

  4. Temperature Inversion and Katabatic Winds are common conditions in dune fields http://www.blackhillsweather.com/inversions.html

  5. Wind Conditions at Mac and Zoe are stable MAC Mean Wind Direction* (azimuth): 217. 11 Mean Wind Speed: 8.72 m/s ZOE Mean Wind Direction* (azimuth): 217.38 Mean Wind Speed: 9.66 m/s

  6. Data Sources • MODIS on Aqua and Terra: band 32 (thermal band 12; 11.770-12.270 m), 1km, v4. 2004. • Mac and Zoe AWS, 2004 AQUA orbit map, http://amrc.ssec.wisc.edu/~amrc/AQUA.GIF Zoe AWS

  7. Four Sizes of View 1650km 200km 500km 2900km

  8. Mac and Zoe AWS data within 1/2 hour used for comparison

  9. Quick Statistics from days with TB, Mac and Zoe data • Mac Mean Surface Temperature: - 50.415 °C • Zoe Mean Surface Temperature: - 49.112 °C • Mac TB Mean Temperature: -50.957 °C (222.193 °K) • Zoe TB Mean Temperature: -50.888 °C (222.262 °K) • Mean TB-AWS Temperature Difference* (surface) Mac: -.542 °C Zoe: -1.776 °C *Greatest differences caused by clouds

  10. Under Some Conditions, Dunes are Visible in Thermal Images Observed: Speed: 2.75 to 9.89 m/s, Direction: 201.7 to 256.7 ° Best: Speed: 3.57 to 8.62 m/s Direction: 212 to 254 ° TB °K km

  11. Under Some Conditions, Katabatic Streaks are Visible in Thermal Images Observed: Speed: 4.45 to 17.53 m/s, Direction: 201.7 to 250.8 ° Best: Speed: 9.85 to 11.84 m/s, Direction: 209.1 to 232.7 ° TB °K km

  12. Day 114 09:20 Day 114 22:05 TB °K Day 135, 09:40 Day 134, 13:50

  13. x x x

  14. TB °K km

  15. TB °K [-- 200 km --]

  16. 48-hr Katabatic Wind Model Map, Parish & Bromwich, Feb. 1991 TB imaged Katabatic winds, day 114, 2004

  17. Conclusions • Katabatic winds and dunes can be imaged in emissive thermal bands. • High detail of katabatic winds is visible in thermal imagery, allowing detailed analysis of flow pattern. • The presence of certain features in thermal imagery can be used to infer weather conditions. • Actual images can be combined with AWS data to study cause-effect relationships with atmospheric conditions and surface features on the plateau, even in the absence of sunlight. Special Thanks to Mark Fahnestock, George Hurtt, and the rest of the R&D team!

  18. Mac and Zoe AWS data

  19. Wind Speed in Theory Vs. Practice • Zoe Mean Wind Speed: 9.66 m/s • Mac Mean Wind Speed: 8.72 m/s • Speed by Parish and Bromwich:

  20. TB °K km

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