Longitudinal and latitudinal variations in dynamic characteristics of the MLT (70−95km): a study involving the CUJO network

Abstract

Abstract. The newly-installed MFR (medium frequencyradarAnnual climatologies involving both height and frequency versus time contour plots for periods from 8 h to 30 days, show that the changes with longitude are very significant and distinctive, often exceeding the local latitudinal variations. Comparisons with models and the recent UARS-HRDI global analysis of tides are discussed. The fits of the horizontal wave numbers of the longer period oscillations are provided in unique frequency versus time contour plots and shown to be consistent with the expected dominant modes. Annual climatologies of planetary waves (16 day, 2 day) and gravity waves reveal strong seasonal and longitudinal variations.

Comment on "Global structure, seasonal and interannual variability of the migrating semidiurnal tide seen in the SABER/TIMED temperatures (2002–2007)" by Pancheva et al. (2009)

“…These results are of course consistent with earlier CUJO papers (Manson et al, 2003(Manson et al, , 2004a where the data are presented in alternate complementary fashion. It is worthy of note, as remarked by one of the reviewers (a tidal specialist) of this Comment paper, that the direct phase-parameter measured is the vertical phase-gradient (degrees per km), and that conversion of this number into a vertical wavelength can be problematic when the height interval used is smaller than the calculated wavelength.…”

Arctic tidal characteristics at Eureka (80° N, 86° W) and Svalbard (78° N, 16° E) for 2006/07: seasonal and longitudinal variations, migrating and non-migrating tides

“…3) and of the spectra for Saskatoon and Collm, again show strong differences between midlatitude and polar tidal oscillations. At 51/52 • N the 12-h peaks are quite prominent, as expected, since there is usually a minor seasonal maximum in spring at these heights (Manson et al, , 2004c, but there is no coherent (monthly mean) 24-h peak. Both sites feature Q2DW peaks.…”

“…There are factors of nearly ten between the March amplitudes, with the zonal component providing the larger differences. The tidal variations with longitude near 40 • N for the CUJO network (Manson et al, 2004c were much smaller; and the hemispheric zonal patterns of amplitude and phase seen in HRDI satellite data from 96 km (Manson et al, 2004a), also for these lower latitudes, were significant but smaller. The hodographs of Figs.…”

“…The first two (AHM, CEM) authors noted from the very beginning of Canadian observations at Eureka (80 • N) that the tidal amplitudes were larger than expected, and that the relative magnitudes of the 24-h and 12-h tides differed from these at Saskatoon, Canada (52 • N). Existing expectations were based upon Saskatoon and Tromso (70 • N) observations (Manson et al, , 2004c. Unique polar information on diurnal non-migrating tides (NMT) has been provided, as well as complementary information to that existing for the Antarctic on the semidiurnal NMT.…”

Wave activity (planetary, tidal) throughout the middle atmosphere (20-100km) over the CUJO network: Satellite (TOMS) and Medium Frequency (MF) radar observations

“…The Saskatoon, London and Platteville MFRs (2.2 MHz) are of very similar design, and have been well described in the first CUJO papers (Manson et al, 2003a(Manson et al, , 2004a. The spaced antenna "full correlation analysis" method is used (Meek, 1980).…”