Small-Scale Features in the Middle Atmosphere Wind Field at Saskatoon, Canada(52°N, 107°W): An Analysis of MF Radar Data with Rocket Comparisons

Abstract

The wind field of the middle atmosphere (60-100 kin) is sampled by the Saskatoon Medium Frequency radar: temporal resolution is normally 5 rain, and vertical is 1.5/3 kin. Profiles are analyzed for gravity waves (GW), and periods r from 10 rain-10 h are measured, with 3,z > 2 km and amplitudes > 5 m s-. The profiles are quite similar to those from rocket soundings. Wind vector shears are also consistent with "wind corners" evident in recent rocket data. Vertical shears of the horizontal wind and GW amplitudes (10 < r < 60 rain)are calculated and shown as annual height-time cross sections; values near 60 km are compared with rocket data from nearby Primrose Lake. Regions favoring dynamic and convective instability and GW saturation are located. The scattered radar power is shown as a seasonal cross section and compared to the shear and GW features. Finally, the dissipation rate of GW kinetic energy is calculated and compared with related MF radar and rocket wind estimations.