Vertical evolution of potential energy density and vertical wave number spectrum of Antarctic gravity waves from 35 to 105km at McMurdo (77.8°S, 166.7°E)

Abstract

We report the first characterization of potential energy densities and verticalwave number spectra of Antarctic gravity waves (GWs) from 35 to 105 km, derived from Fe lidar temperature measurements at McMurdo (77.8°S, 166.7°E) in 2011-2013 winters. For GWs with periods of 2-10 h, the potential energy density per unit volume (Epv) decreases by 2 orders of magnitude from 35 to 105 km, while that per unit mass (Epm) increases from several to hundreds of J/kg. Epm increases with a mean scale height of ~10.4km in the Rayleigh region (35-65 km) and of ~13.2 kmin the Fe region (81-105km), and of particular interest is the inferred severe dissipation in between (65-81km). Overall, the vertical evolutions of Epv and Epm indicate considerable wave energy loss from the stratosphere to the lower thermosphere. The vertical wave number spectra exhibit power law forms for vertical wavelengths λz 10 km in 35-60km. PSDs increase by 1 order of magnitude from the stratosphere to the lower thermosphere. Using higher temporal resolution data to include 0.5-2 h waves increase Epm by ~25-45% and increase PSDs of 2-5 km waves by a factor of 2 and of >10km waves by less than 50%.