Journal of Geophysical Research Atmospheres
American Geophysical Union
A novel investigation of terdiurnal (8-hour) oscillations in the mesosphere and lower-thermosphere temperature and wind field over Maui, Hawaii (20.8°N, 156.2°W) has been performed. Coincident observations using a mesospheric temperature mapper and a meteor wind radar were obtained since May 2002 as part of the Maui Mesosphere and Lower Thermosphere (Maui MALT) program to investigate the seasonal structure and dynamics of the low-latitude middle atmosphere. This study focuses on a 10-day period in July 2002 when a persistent ∼8-hour oscillation was identified in dual measurements of the OH (6,2) and O2 (0,1) nocturnal rotational temperatures sampled at nominal altitudes of 87 and 94 km, respectively. During the summer months, the semidiurnal and diurnal tidal temperature components are expected to be minimal, and these data are most suitable for investigating the terdiurnal wave component, which is usually much weaker. Our results show that the primary 8-hour oscillation observed during this 10-day period exhibited a mean amplitude ∼5.5 K and a well-defined phase shift (∼1-hour) between the OH and O2 temperatures (with the O2 oscillation always leading). The downward phase progression and inferred mean vertical wavelength of ∼63 km are most consistent with that expected for the terdiurnal tide. Coincident meteor radar measurements also show an intermittent 8-hour periodicity in the wind data. In particular, a detailed comparison of the winds and temperatures over a 4-day interval within this period suggests a significant correlation indicating a near in-phase temperature relation with the meridional wind component and a near-antiphase relation with the zonal wind component. Comparison of the OH and O2 8-hour temperature amplitudes also shows strong evidence for highly variable wave dissipation, with amplitude growth factors ranging from 0.6 to 1.9 throughout this period.
Taori, A., M.J. Taylor and S. Franke, Terdiurnal wave signatures in the upper mesospheric temperature and their association with the wind fields at low-latitudes (20°N), J. Geophys. Res. Atmos., 110, D09S06, doi:10.1029/2004JD004564, 2005.