Dynamical response of low-latitude middle atmosphere to major sudden stratospheric warming events |
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| Authors: | S Sathishkumar S Sridharan Ch Jacobi |
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| Institution: | 1. Equatorial Geophysical Research Laboratory, Indian Institute of Geomagnetism, Krishnapuram, Tirunelveli 627011, India;2. National Atmospheric Research Laboratory, Gadanki 517 112, Pakala Mandal, Chittoor District, India;3. Institut für Meteorologie, Universität Leipzig, Stephanstr. 3, D-04103 Leipzig, Germany;1. Laboratoire de Chimie Moléculaire et Thio-organique (UMR CNRS 6507), ENSICAEN – Université de Caen, 6 Boulevard Maréchal Juin, 14050 Caen, France;2. CEA, LIST, Laboratoire Capteurs et Architectures Électroniques, CEA Saclay, 91191 Gif-sur-Yvette, France;3. Laboratoire d''Innovation Thérapeutique (UMR CNRS 7200), Faculté de Pharmacie, Université de Strasbourg, 74 route du Rhin, 67401 Illkirch, France;4. Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques (UMR CNRS 8601), Université René Descartes, 45 rue des Saints-Pères, 75270 Paris 06, France;5. Institute of Condensed Matter Physics, Faculty of Science, Masaryk University, Kotlá?ská 2, 61137 Brno, Czech Republic;1. Institut de Recherche en Génie Civil et Mécanique (GeM, UMR 6183 CNRS), École Centrale Nantes, 1 rue de la Noë, BP 92101, F-44321 Nantes, France;2. Institute of Mechanics, Materials and Civil Engineering (iMMC), Université catholique de Louvain, 4 ave. G. Lemaître, B-1348 Louvain-la-Neuve, Belgium;1. Space Science Division, Naval Research Laboratory, Washington, DC, USA;2. Remote Sensing Division, Naval Research Laboratory, Washington, DC, USA;3. Space Weather Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, USA;4. Leibniz-Institute for Atmospheric Physics, Rostock University, Kühlungsborn, Germany;5. Norwegian University of Science and Technology (NTNU), Trondheim, Norway;6. Marine Meteorology Division, Naval Research Laboratory, Monterey, CA, USA;7. Department of Physics & Astronomy, University of Western Ontario, London, Ontario, Canada;8. GATS Inc., Boulder, CO, USA;9. University of Leipzig, Leipzig, Germany;10. Centre for Space, Atmospheric and Oceanic Science, University of Bath, Bath, UK |
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| Abstract: | The zonally averaged UK Meteorological Office (UKMO) zonal mean temperature and zonal winds for the latitudes 8.75°N and 60°N are used to investigate the low-latitude dynamical response to the high latitude sudden stratospheric warming (SSW) events that occurred during winter of the years 1998–1999, 2003–2004 and 2005–2006. The UKMO zonal mean zonal winds at 60°N show a short-term reversal to westward winds in the entire upper stratosphere and lower mesosphere and the low-latitude winds (8.75°N) show enhanced eastward flow in the upper stratosphere and strong westward flow in the lower mesosphere during the major SSW events at high latitudes. The mesosphere and lower thermosphere (MLT) zonal winds acquired by medium frequency (MF) radar at Tirunelveli (8.7°N, 77.8°E) show a change of wind direction from eastward to westward several days before the onset of SSW events and these winds decelerate and weak positive (eastward) winds prevail during the SSW events. The time variation of zonal winds over Tirunelveli is nearly similar to the one reported from high latitudes, except that the latter shows intense eastward winds during the SSW events. Besides, the comparison of daily mean meridional winds over Tirunelveli with those over Collm (52°N, 15°E) show that large equatorial winds are observed over Tirunelveli during the 2005–2006 event and over Collm during the 1998–1999 events. The variable response of MLT dynamics to different SSW events may be explained by the variability of gravity waves. |
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