Geodesy

Gravity wave

QUIET

Astrophysics

Seismology

Geology

Thermodynamics

Ionosphere

Physics

Stratosphere

Instability

Advection

Astronomy

Gravitational wave

Geophysics

Thermosphere

Atmospheric sciences

Mechanics

Journal of Geophysical Research Space Physics

We analyze quiet‐time data from the Gravity Field and Ocean Circulation Explorer satellite as it overpassed the Southern Andes at z ≃275 km on 5 July 2010 at 23 UT. We extract the 20 largest traveling atmospheric disturbances from the density perturbations and cross‐track winds using Fourier analysis. Using gravity wave (GW) dissipative theory that includes realistic molecular viscosity, we search parameter space to determine which hot spot traveling atmospheric disturbances are GWs. This results in the identification of 17 GWs having horizontal wavelengths λ H = 170–1,850 km, intrinsic periods τ I r = 11–54 min, intrinsic horizontal phase speeds c I H = 245–630 m/s, and density perturbations 0.03–7%. We unambiguously determine the propagation direction for 11 of these GWs and find that most had large meridional components to their propagation directions. Using reverse ray tracing, we find that 10 of these GWs must have been created in the mesosphere or thermosphere. We show that mountain waves (MWs) were observed in the stratosphere earlier that day and that these MWs saturated at z ∼ 70–75 km from convective instability. We suggest that these 10 Gravity Field and Ocean Circulation Explorer hot spot GWs are likely tertiary (or higher‐order) GWs created from the dissipation of secondary GWs excited by the local body forces created from MW breaking. We suggest that the other GW is likely a secondary or tertiary (or higher‐order) GW. This study strongly suggests that the hot spot GWs over the Southern Andes in the quiet‐time middle winter thermosphere cannot be successfully modeled by conventional global circulation models where GWs are parameterized and launched in the troposphere or stratosphere.

Characteristics of the Quiet‐Time Hot Spot Gravity Waves Observed by GOCE Over the Southern Andes on 5 July 2010