Observations of mesospheric wind velocities, 1. Gravity wave horizontal scales and phase velocities determined from spaced wind observations

摘要

Horizontal scales and phase velocities of upper middle atmosphere (60-110 km) gravity waves determined from preliminary analysis of spaced wind observations obtained with a dual bistatic radar (Gravnet), based on and operated together with the Saskatoon MF radar are presented. In the observed period range of 10-100 min, horizontal scales increase from values of ∼44 km at 10 min to -211 km at 100 min, while observed phase speeds decrease from values of ∼72 m/s at 10 min to ∼34 m/s at 100 min. Typical rms perturbation velocities are -5 m/s. Calculation of intrinsic wave parameters indicates that in the intrinsic period range of 10-100 min, horizontal scales increase from values of ∼68 km at 10 min to ∼119 km at 100 min, with intrinsic phase speeds of ∼93 m/s at 10 min and ∼20 m/s at 100 min. The corresponding values of vertical wavelength are 30 km and 6 km, respectively.