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Ann. Geophys., 20, 1447-1467, 2002
www.ann-geophys.net/20/1447/2002/
© European Geosciences Union 2002
Temperature tides determined with meteor radar
W. K. Hocking1 and A. Hocking2
1Dept. of Physics and Astronomy, University of Western Ontario, London, Ont., N6A 3K7, Canada
2Mardoc Inc., London, Ont., N6G 4N4, Canada
Correspondence to: A. Hocking (mardoc-inc@rogers.com)
Abstract. A new analysis method for
producing tidal temperature parameters using meteor radar measurements is
presented, and is demonstrated with data from one polar and two mid-latitude
sites. The technique further develops the temperature algorithm originally
introduced by Hocking (1999). That earlier method was used to produce
temperature measurements over time scales of days and months, but required an
empirical model for the mean temperature gradient in the mesopause region.
However, when tides are present, this temperature gradient is modulated by the
presence of the tides, complicating extraction of diurnal variations.
Nevertheless, if the vertical wavelengths of the tides are known from wind
measurements, the effects of the gradient variations can be compensated for,
permitting determination of temperature tidal amplitudes and phases by meteor
techniques. The basic theory is described, and results from meteor radars at
Resolute Bay (Canada), London (Canada) and Albuquerque (New Mexico, USA) are
shown. Our results are compared with other lidar data, computer models,
fundamental tidal theory and rocket data. Phase measurements at two
mid-latitude sites (Albuquerque, New Mexico, and London, Canada) show times of
maximum for the diurnal temperature tide to change modestly throughout most of
the year, varying generally between 0 h and 6 h, with an excursion to 12 h in
June at London. The semidiurnal tide shows a larger annual variation in time of
maximum, being at 2–4 h in the winter months but increasing to 9 h during the
late summer and early fall. We also find that, at least at mid-latitudes, the
phase of the temperature tide matches closely the phase of the meridional tide,
and theoretical justification for this statement is given. We also demonstrate
that this is true using the Global Scale Wave Model (Hagan et al., 1999).
Median values for the temperature amplitudes for each site are in the range 5
to 6 Kelvin. Results from a more northern site (Resolute Bay) show less
consistency between the wind tides and the temperature tides, supporting
suggestions that the temperature tides may be zonally symmetric at these high
latitudes (e.g. Walterscheid and Sivjee, 2001).
Key words. Meteorology and
atmospheric dynamics (middle atmosphere dynamics; waves and tides) – Radio
science (signal processing)
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