Mean winds and tidal and planetary wave motions over Hawaii during airborne lidar and observations of Hawaiian Airglow ALOHA‐93

Abstract

The mean and low‐frequency wave motions in the mesosphere and lower thermosphere from 70 to 98 km were observed with the MF radar on Kauai during the Airborne Lidar and Observations of Hawaiian Airglow ALOHA‐93 measurement campaign. Two‐day mean zonal winds exhibited a transition from a variable structure with altitude at the beginning of October having westward motions near 80 km and eastward motions at upper and lower levels to more uniform eastward winds with altitude at the end of October. Two‐day mean meridional motions were equally variable, with northward motions at all altitudes on October 1, northward motions above ∼80 km and southward motions below throughout much of the campaign, and largely northward motions at the end of October. Zonal and meridional winds exhibited significant oscillations at ∼5 to 30 day periods, indicative of planetary wave activity during this interval. Diurnal tidal amplitudes and phases were likewise variable, with maximum and minimum rms amplitudes of ∼ 35 and 10 ms−1, approximate phase quadrature with meridional leading zonal, amplitude and phase variability on time scales of ∼ 5 to 15 days, and an overall phase advance during October of ∼10 h. Other tidal components and the two‐day wave had rms amplitudes of ∼ 5 to 10 ms−1.