Extracting gravity wave parameters during the September 2002 Southern Hemisphere major sudden stratospheric warming using a SANAE imaging riometer

• Published in: Annales Geophysicae
• Main Authors: Mbatha, Nkanyiso, Sivakumar, Venkataraman, Bencherif, Hassan, Malinga, Sandile B.
• Other Authors: South African National Space Agency (SANSA), South African National Space Agency, University of KwaZulu-Natal Durban, Afrique du Sud (UKZN), Laboratoire de l'Atmosphère et des Cyclones (LACy), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Météo-France
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2013
• Subjects: [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]; Antarctic; SANAE; Antarc*; Antarctica
• Online Access: https://hal.univ-reunion.fr/hal-01387268; https://hal.univ-reunion.fr/hal-01387268/document; https://hal.univ-reunion.fr/hal-01387268/file/Mbatha%20et%20al,%20ANG%202013_hal%20%281%29.pdf; https://doi.org/10.5194/angeo-31-1709-2013

International audience Using absorption data measured by imaging ri-ometer for ionospheric studies (IRIS) located at the South Africa National Antarctic Expedition (SANAE), Antarctica (72 • S, 3 • W), we extracted the parameters of gravity waves (GW) of periods between 40 and 50 min during late win-ter/spring of the year 2002, a period of the unprecedented major sudden stratospheric warming (SSW) in the Southern Hemisphere middle atmosphere. During this period, an unprecedented substantial increase of temperature by about 25– 30 K throughout the stratosphere was observed. During the period of the occurrence of the major stratospheric warming , there was a reduction of both the GW horizontal phase speeds and the horizontal wavelengths at 90 km. The GW phase speeds and horizontal wavelengths were observed to reach minimum values of about 7 m s −1 and 19 km, respectively , while during the quiet period the average value of the phase speed and horizontal wavelength was approximately 23 m s −1 and 62 km, respectively. The observed event is discussed in terms of momentum flux and also a potential interaction of gravity waves, planetary waves and mean circulation.