A Neutral Wave Observed in the Antarctic Polar Vortex

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Abstract

An intensive radiosonde observation with time intervals of 3 h was performed in June 2002 at Syowa Station (39.6°E, 69°S) in the Antarctic. A wavelike disturbance with a wave period of 12-15 h, having a nearly barotropic structure was observed above a height of 22km in the time period of 27-28 June 2002. A result of the hodograph analysis suggests that the short-period disturbance is not due to an inertiagravity wave. A similar short-period disturbance is observed in the European Centre for Medium-Range Weather Forecasts (ECMWF) operational analysis data. Results of detailed analysis using the ECMWF data show that the short-period disturbance has a horizontal wavelength of about 2000km, and propagates along a potential vorticity minimum region with a horizontal phase velocity of about 40m s^<-1>. This phase velocity is equal to the background horizontal wind velocity at the potential vorticity minimum. A necessary condition for the barotropic instability is locally satisfied at the potential vorticity minimum. However, it is rather appropriate that the short-period disturbance is interpreted as a neutral wave than as an unstable wave in the barotropically unstable background flow. This result implies any unknown mechanism of the suppression of barotropic instability in the locally unstable background flow associated with a disturbed polar vortex.

Journal

  • Journal of the Meteorological Society of Japan

    Journal of the Meteorological Society of Japan 84(1), 97-113, 2006-02-26

    Meteorogical Society of Japan

References:  25

Codes

  • NII Article ID (NAID)
    110004656446
  • NII NACSIS-CAT ID (NCID)
    AA00702524
  • Text Lang
    ENG
  • Article Type
    ART
  • ISSN
    00261165
  • NDL Article ID
    7832560
  • NDL Source Classification
    ZM43(科学技術--地球科学--気象)
  • NDL Call No.
    Z54-J645
  • Data Source
    CJP  NDL  NII-ELS  NDL-Digital 
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