Shelley Knuth June 8, 2004 AWS Annual Meeting An Analysis of Surface Wind Speeds at Dome C, Antarctica C. Meyer and J.W.V. Storey School of Physics/Univ. of New South Wales Presented on their behalf by Shelley L. Knuth Antarctic Meteorological Research Center

Shelley Knuth June 8, 2004 AWS Annual Meeting An Analysis of Surface Wind Speeds at Dome C, Antarctica Outline Introduction/Purpose Dome C and Astronomy Results Conclusion

Shelley Knuth June 8, 2004 AWS Annual Meeting An Analysis of Surface Wind Speeds at Dome C, Antarctica Introduction/Purpose AWS/AMRC project assists many scientists in other fields Provided twenty years worth of data from Dome C

Shelley Knuth June 8, 2004 AWS Annual Meeting An Analysis of Surface Wind Speeds at Dome C, Antarctica Introduction (Cont.) Wind speeds important to deployment of telescopes –Telescopes have to survive – higher winds cause more stress on telescopes, especially the ELT’s –Wind loads must not deform mirrors by more than a few tens of nm. – moves less with lower wind speeds –High wind speeds create turbulent ground layer and reduce telescope resolution. –Low wind speeds increase time available to focus on a Guide Star which allows for fainter stars to be used

Shelley Knuth June 8, 2004 AWS Annual Meeting An Analysis of Surface Wind Speeds at Dome C, Antarctica Introduction (ctd.) –Longer exposure allows you to "see" farther out into space without having the view distorted by turbulence (sort of like the heat shimmer that comes off the pavement on a hot day). –High wind speeds result in higher dust or ice crystal levels, which reduce the operational abilities of the telescope –Ground layer only turbulence in the atmosphere so allows unprecedented image quality over a wide field

Shelley Knuth June 8, 2004 AWS Annual Meeting An Analysis of Surface Wind Speeds at Dome C, Antarctica Dome C and Astronomy Lat/Lon: (ca. 1980) 74.5S, E, 3280m and (ca. 1995) 75.12S, E, 3250m Exceptionally low wind speeds because high on plateau and are just starting their flow down the mountains Thin boundary layer Excellent place for an astronomical observatory

Shelley Knuth June 8, 2004 AWS Annual Meeting An Analysis of Surface Wind Speeds at Dome C, Antarctica Dr. Anna Moore of the Anglo-Australian Observatory

Shelley Knuth June 8, 2004 AWS Annual Meeting An Analysis of Surface Wind Speeds at Dome C, Antarctica

Shelley Knuth June 8, 2004 AWS Annual Meeting An Analysis of Surface Wind Speeds at Dome C, Antarctica Results Mean monthly wind speed at Dome C and Dome C II from the beginning of 1984 to the end of 2003.

Shelley Knuth June 8, 2004 AWS Annual Meeting An Analysis of Surface Wind Speeds at Dome C, Antarctica Figure 2. Wind rose, showing the probability that the wind will be of a particular speed and in a particular direction, for Dome C and Dome C II combined, for the same period as in Figure 1.

Shelley Knuth June 8, 2004 AWS Annual Meeting An Analysis of Surface Wind Speeds at Dome C, Antarctica Table 1. Mean wind speeds at Dome C and at other astronomical sites for which long-term data exist.

Shelley Knuth June 8, 2004 AWS Annual Meeting An Analysis of Surface Wind Speeds at Dome C, Antarctica Figure 4. Probability histogram for 1990 showing all data (top panel), winter months (middle panel), and astronomical darkness (lower panel). Also shown is the cumulative probability.

Shelley Knuth June 8, 2004 AWS Annual Meeting An Analysis of Surface Wind Speeds at Dome C, Antarctica Figure 7. Probability histogram for 2003 showing all data (top panel), winter months (middle panel), and astronomical darkness (lower panel). Also shown is the cumulative probability.

Shelley Knuth June 8, 2004 AWS Annual Meeting An Analysis of Surface Wind Speeds at Dome C, Antarctica Conclusions Dome C winds are very low Winds many times are even null Incredible advantage for telescope designers Good place for the new Extremely Large Telescope and proposed Antarctic Planet Interferometer

Shelley Knuth June 8, 2004 AWS Annual Meeting An Analysis of Surface Wind Speeds at Dome C, Antarctica Acknowledgments Linda Keller – AWS Data Peter Gillingham, Panayiotis Tzanavaris, and Jon Everett at UNSW Support from Australian Research Council

Shelley Knuth June 8, 2004 AWS Annual Meeting An Analysis of Surface Wind Speeds at Dome C, Antarctica Figure 3. Probability histogram for 1984 showing all data (top panel), winter months (middle panel), and astronomical darkness (lower panel). Also shown is the cumulative probability.

Shelley Knuth June 8, 2004 AWS Annual Meeting An Analysis of Surface Wind Speeds at Dome C, Antarctica Figure 5. Probability histogram for 1996 showing all data (top panel), winter months (middle panel), and astronomical darkness (lower panel). Also shown is the cumulative probability.

Shelley Knuth June 8, 2004 AWS Annual Meeting An Analysis of Surface Wind Speeds at Dome C, Antarctica Figure 6. Probability histogram for 2002 showing all data (top panel), winter months (middle panel), and astronomical darkness (lower panel). Also shown is the cumulative probability.