Observations of High Frequency GWs observed in mesospheric airglow, and the implication to the GW imposed zonal stress and the residual circulation Gary R. Swenson1, Fabio Vargas1, Alan Liu2, Xian Lu3, Zhenhua Li3, Chester Gardner1 Electrical and Computer Engineering, University of Illinois, Urbana, IL, United States. Physical Sciences, Embry Riddle Aeronautical University, Daytona Beach, FL, United States. Atmospheric Sciences, University of Illinois, Urbana, IL, United States.

OH emission altitudes] Introduction The background atmosphere and meridional circulation OH and mesospheric airglows, and altitude weighting functions, I’/I Directional statistics, and methods [Globally, the meridional component is toward the summer pole, at OH emission altitudes] Momentum flux, methods of determination from airglow Freely propagating versus damped Momentum flux, statistical summary from a Brazilian study Summary

The Lower and Middle Atmosphere 10 20 30 40 50 60 70 80 90 km 270 1013 55 11 3 0.7 0.2 0.05 0.009 0.003 Pres (mbar) Equator Pole (WINTER) (SUMMER) Created by A. J. Gerrard, 10/99, based heavily on M. R. Schoeberl’s depiction Zonal Winds Zonal Temps Gravity Waves (boxes are areas of induced drag) Planetary Waves Circulation

Atmosphere with Motion Upper atmosphere with cold summer and warm winter polar mesosphere Atmosphere with Motion

Residual Meridional Circulation Northern Winter H.-L. Liu. (2007)

λx= 28 km Cg= 40 m/s Ci= 40 m/s λz= 28 km σ~±10 km Quasi monochromatic gravity waves-ever present λx= 28 km Cg= 40 m/s Ci= 40 m/s 75- 85- 95- 105- O(1S) O2 Height (km) λz= 28 km OH σ~±10 km 10 20 30 40 Horizontal Distance (km)

Dispersion Relationship Wave domain plot, intrinsc phase speed vs horizontal wavelength, versus vertical wavelength

Airglow Layers Vargas et al. (2007)

GW Statistics Propagation Direction Maui, HI Tang et al. (2005) Cachoeira Paulista, BR Vargas (2007), Phd Theses

List of References

Meridional Propagation Direction Northern Summer

Meridional Propagation Direction Northern Summer

Meridional Propagation Direction Northern Winter

Meridional Propagation Direction Northern Winter

Dissipation of GWs (Lidar) Freely Propagating Saturated Damped Fritts (1984)

Dissipation of AGWs (Airglow) OH O2 O(1S) Spatial Series Cross-Spectra Amplitude wave amplitude decreasing with altitude Vargas et al. (2011), in preparation

Modeled MF Divergence Dissipating AGWs Vargas et al, (2007)

Measured Flux Divergence Dissipating AGWs (I’/I ≥ 1%) Southern Hemisphere Vargas (2007), Phd Theses

Summary A globally distributed set of ground based observations has been analyzed for the winter and summer directions of wave propagation. There is experimental evidence that wave forcing is globally significant and opposite to the summer-winter residual meridional flow, predominantly propagating toward the summer pole. AGW stress acting against the meridional flow imposes a deceleration which biases the magnitude of the meridional circulation (underestimates).