Blar i forfatter Artikler, rapporter og annet (TGO) "Meek, C.E."

Viser treff 1-5 av 5

    • The 16-day planetary waves: multi-MF radar observations from the arctic to equator and comparisons with the HRDI measurements and the GSWM modelling results 

      Hall, Chris; Luo, Y.; Manson, A.H.; Meek, C.E.; Meyer, C.K.; Burrage, M.D.; Fritts, D.C.; Hocking, W.K.; MacDougall, J.; Riggin, D.M.; Vincent, R.A. (Journal article; Peer reviewed; Tidsskriftartikkel, 2002)
      The mesospheric and lower thermospheric (MLT) winds (60–100 km) obtained by multiple MF radars, located from the arctic to equator at Tromsø (70° N, 19° E), Saskatoon (52° N, 107° W), London (43° N, 81° W), Hawaii (21° N, 157° W) and Christmas Island (2° N, 157° W), respectively, are used to study the planetary-scale 16-day waves. Based on the simultaneous observations (1993/1994), the variabilities ...

    • Isolated lower mesospheric echoes seen by medium frequency radar at 70º N, 19º E 

      Hall, Chris; Manson, A.H.; Meek, C.E.; Nozawa, S. (Journal article; Peer reviewed; Tidsskriftartikkel, 2006-11-23)
      We have noted sporadic instances of strong isolated reflections of medium frequency (MF) radar waves from the mesosphere from as low as 50 km altitude and have devised a set of criteria for isolating these apparently anomalous echoes from those normally occurring from progressive partial reflections in the D-region. The object of this study is to map the occurrences of such echoes facilitating ...

    • Periodicities in energy dissipation rates in the auroral mesosphere/lower thermosphere 

      Nozawa, S.; Hall, Chris; Meek, C.E.; Manson, A.H.; Luo, Yi (Journal article; Peer reviewed; Tidsskriftartikkel, 2003)
      It is possible for medium-frequency (MF) radar systems to estimate kinetic energy dissipation rates by measuring signal fading times. Here, we present approximately 5 years of such results from Tromsø (69° N, 19° E) and in particular, investigate the periodicities present at different altitudes in the regime 80 to 100 km. We detect the known annual variation in the mesosphere and the semiannual ...

    • Testing the hypothesis of the influence of neutral turbulence on the deduction of ambipolar diffusivities from meteor trail expansion 

      Hall, Chris; Aso, T.; Tsutsumi, M.; Nozawa, S.; Manson, A.H.; Meek, C.E. (Journal article; Peer reviewed; Tidsskriftartikkel, 2005-03-30)
      Fading times of radar echoes from underdense meteor trails in the upper mesosphere/lower thermosphere are commonly used to determine ambipolar diffusivities and hence ambient temperature. Diffusivities are generally expected to increase exponentially with height through the region from which the meteor trail echoes are obtained, viz., typically 70-110km altitude for a ~30-MHz radar. In practice, ...

    • Tidal signatures in mesospheric turbulence 

      Nozawa, S.; Hall, Chris; Manson, A.H.; Meek, C.E. (Journal article; Peer reviewed; Tidsskriftartikkel, 2006)
      We search for the presence of tidal signatures in high latitude mesospheric turbulence as parameterized by turbulent energy dissipation rate estimated using a medium frequency radar, quantifying our findings with the aid of correlation analyses. A diurnal periodicity is not particularly evident during the winter and spring months but is a striking feature of the summer mesopause. While semidiurnal ...