THE ANTARCTICA POLAR VORTEX: STUDY OF WINTER...
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THE ANTARCTICA POLAR VORTEX: THE ANTARCTICA POLAR VORTEX: STUDY OF WINTER 2005 STUDY OF WINTER 2005 F. Lascaux F. Lascaux (1) (1) , , E. Masciadri E. Masciadri (1) (1) , , S. Hagelin S. Hagelin (1,2) (1,2) & J. Stoesz & J. Stoesz (1) (1) (1) (1) INAF/Osservatorio Astrofisico di Arcetri, Florence, Italy INAF/Osservatorio Astrofisico di Arcetri, Florence, Italy (2) (2) Uppsala Universitet, Department of Earth Sciences, Uppsala, Swe Uppsala Universitet, Department of Earth Sciences, Uppsala, Swe den den e e - - mail: mail: [email protected] [email protected] , [email protected] , [email protected] 1. Abstract 3. Mean position of the vortex from May 2005 to September 2005 Acknowledgements: This work has been funded by the Marie Curie Excellence Grant (FOROT) – MEXT-CT-2005-023878 During winter and springtime, the flow above Antarctica at high altitude (upper troposphere and stratosphere) is dominated by the presence of a vortex centered above the continent. It lasts typically from August to November. This vortex is characterized by a strong cyclonic jet centered above the polar high. In a recent study of four different sites in the Antarctic internal plateau (South Pole, Dome C, Dome A and Dome F), Hagelin et al. [1] made the hypothesis that the wind speed strength in the upper atmosphere should be related to the distance of the site to the center of the Antarctic polar vortex. This high altitude wind is very important from an astronomical point of view since it can influence strongly some optical turbulence parameters. What we are interested in here is to localize the position of the minimum wind in altitude. For that we studied the analyses from the ECMWF for winter 2005 at different levels. We deduced a preferred position of this minimum, tilted with altitude, in a zone between South Pole and Dome A, for winter 2005. This extensive study over one entire winter confirms the “position space” of the polar high deduce by Hagelin et al. [1]. 2. Month of August 2005, day by day Wind speed at H=15 km Wind speed at H=20 km MAY 2005 JUN 2005 JUL 2005 AUG 2005 SEP 2005 15 KM 20 KM 15 KM 20 KM Median of wind speed between MAY 2005 and SEPTEMBER 2005 Isocontours of monthly median wind speed (between 3 m/s and 40 m/s). CONCLUSION: Preferred position of the vortex in wnter 2005 between South Pole and Dome A, in agreement with former hypothesis made by Hagelin et al. [1]. References : [1] Hagelin et al., 2008, MNRAS, 387, 4, 1499. 01/08 02/08 03/08 04/08 05/08 06/08 07/08 08/08 11/08 12/08 13/08 14/08 15/08 16/08 17/08 18/08 21/08 22/08 23/08 24/08 25/08 26/08 27/08 28/08 19/08 01/08 09/08 20/08 29/08 30/08 31/08 01/08 02/08 03/08 04/08 05/08 06/08 07/08 08/08 11/08 12/08 13/08 14/08 15/08 16/08 17/08 18/08 21/08 22/08 23/08 24/08 25/08 26/08 27/08 28/08 19/08 01/08 09/08 20/08 29/08 30/08 31/08
Transcript of THE ANTARCTICA POLAR VORTEX: STUDY OF WINTER...
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THE ANTARCTICA POLAR VORTEX: THE ANTARCTICA POLAR VORTEX:
STUDY OF WINTER 2005STUDY OF WINTER 2005F. Lascaux F. Lascaux (1)(1),, E. Masciadri E. Masciadri (1)(1),, S. Hagelin S. Hagelin (1,2) (1,2) & J. Stoesz & J. Stoesz (1)(1)
(1) (1) INAF/Osservatorio Astrofisico di Arcetri, Florence, ItalyINAF/Osservatorio Astrofisico di Arcetri, Florence, Italy(2)(2) Uppsala Universitet, Department of Earth Sciences, Uppsala, SweUppsala Universitet, Department of Earth Sciences, Uppsala, Swe denden
ee--mail: mail: [email protected]@arcetri.astro.it , [email protected], [email protected]
1. Abstract
3. Mean position of the vortex from May 2005 to September 2005
Acknowledgements: This work has been funded by the Marie Curie Excell ence Grant (FOROT) – MEXT-CT-2005-023878
During winter and springtime, the flow above Antarctica at high altitude (upper troposphere and stratosphere) is dominated by the presence of a vortex centered above the continent. It lasts typically from August to November. This vortex is characterized by a strong cyclonic jet centered above the polar high.In a recent study of four different sites in the Antarctic internal plateau (South Pole, Dome C, Dome A and Dome F), Hagelin et al. [1] made the hypothesis that the wind speed strength in the upper atmosphere should be related to the distance of the site to the center of the Antarctic polar vortex. This high altitude wind is very important from an astronomical point of view since it can influence strongly some optical turbulence parameters. What we are interested in here is to localize the position of the minimum wind in altitude. For that we studied the analyses from the ECMWF for winter 2005 at different levels. We deduced a preferred position of this minimum, tilted with altitude, in a zone between South Pole and Dome A, for winter 2005. This extensive study over one entire winter confirms the “position space” of the polar high deduce by Hagelin et al. [1].
2. Month of August 2005, day by day
Wind speedat H=15 km
Wind speedat H=20 km
MAY 2005 JUN 2005 JUL 2005 AUG 2005 SEP 2005
15 KM
20 KM
15 KM 20 KM
Median of wind speed between MAY 2005 and SEPTEMBER 2005Isocontours of monthly median wind speed (between 3 m/s and 40 m/s).
CONCLUSION:Preferred position of the vortex in wnter 2005 between South Pole and Dome A, in agreement with former hypothesis made by Hagelin et al. [1].
References :[1] Hagelin et al., 2008, MNRAS, 387, 4, 1499.
01/08 02/08 03/08 04/08 05/08 06/08 07/08 08/08
11/08 12/08 13/08 14/08 15/08 16/08 17/08 18/08
21/08 22/08 23/08 24/08 25/08 26/08 27/08 28/08
19/08
01/08 09/08
20/08
29/08 30/08 31/08
01/08 02/08 03/08 04/08 05/08 06/08 07/08 08/08
11/08 12/08 13/08 14/08 15/08 16/08 17/08 18/08
21/08 22/08 23/08 24/08 25/08 26/08 27/08 28/08
19/08
01/08 09/08
20/08
29/08 30/08 31/08
