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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 20, issue 5
Ann. Geophys., 20, 661–677, 2002
https://doi.org/10.5194/angeo-20-661-2002
© Author(s) 2002. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 20, 661–677, 2002
https://doi.org/10.5194/angeo-20-661-2002
© Author(s) 2002. This work is distributed under
the Creative Commons Attribution 3.0 License.

  31 May 2002

31 May 2002

Seasonal variations of the semi-diurnal and diurnal tides in the MLT: multi-year MF radar observations from 2–70° N, modelled tides (GSWM, CMAM)

A. H. Manson1, C. Meek1, M. Hagan2, J. Koshyk3, S. Franke4, D. Fritts5, C. Hall6, W. Hocking7, K. Igarashi8, J. MacDougall7, D. Riggin5, and R. Vincent9 A. H. Manson et al.
  • 1Institute of Space and Atmospheric Studies, University of Saskatchewan, Canada
  • 2NCAR, Boulder NCAR, Boulder, USA
  • 3Department of Physics, University of Toronto, Canada
  • 4Space Science and Remote Sensing Laboratory, University of Illinois, USA
  • 5Colorado Research Associates (a Division of Northwest Research Associates), Boulder, USA
  • 6Auroral Observatory, University of Tromsø, Norway
  • 7Department of Physics and Astronomy, University of Western Ontario, Canada
  • 8Communications Research Laboratory, Tokyo, Japan
  • 9Department of Physics and Mathematical Physics, University of Adelaide, Australia
  • Correspondence to: A. H. Manson
  • (manson@dansas.usask.ca)

Abstract. In an earlier paper (Manson et al., 1999a) tidal data (1990–1997) from six Medium Frequency Radars (MFR) were compared with the Global Scale Wave Model (GSWM, original 1995 version). The radars are located between the equator and high northern latitudes: Christmas Island (2° N), Hawaii (22° N), Urbana (40° N), London (43° N), Saskatoon (52° N) and Tromsø (70° N). Common harmonic analysis was applied, to ensure consistency of amplitudes and phases in the 75–95 km height range. For the diurnal tide, seasonal agreements between observations and model were excellent while for the semi-diurnal tide the seasonal transitions between clear solstitial states were less well captured by the model.

Here the data set is increased by the addition of two locations in the Pacific-North American sector: Yamagawa 31° N, and Wakkanai 45° N. The GSWM model has undergone two additional developments (1998, 2000) to include an improved gravity wave (GW) stress parameterization, background winds from UARS systems and monthly tidal forcing for better characterization of seasonal change. The other model, the Canadian Middle Atmosphere Model (CMAM) which is a General Circulation Model, provides internally generated forcing (due to ozone and water vapour) for the tides.

The two GSWM versions show distinct differences, with the 2000 version being either closer to, or further away from, the observations than the original 1995 version. CMAM provides results dependent upon the GW parameterization scheme inserted, but one of the schemes provides very useful tides, especially for the semi-diurnal component.

Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides)

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