[1] Gravity waves (GWs) play critical roles in the global circulation and the temperature and constituent structures in the middle atmosphere. They also play significant roles in the dynamics and transport and mixing processes in the upper troposphere and lower stratosphere and can affect tropospheric weather. Despite significant advances in our understanding of GWS and their effects in different regions of the atmosphere in the past few decades, observational constraints on GW parameters including momentum flux and propagation direction are still sorely lacking. Global Positioning System (GPS) radio occultation (RO) technique provides global, all-weather, high vertical resolution temperature profiles in the stratosphere and troposphere. The unprecedentedly large number of combined temperature soundings from the Constellation Observing System for Meteorology, Ionosphere, and Climate and Challenging Minisatellite Payload GPS RO missions allows us to obtain GW perturbations by removing the gravest zonal modes using the wavelet method for each day. We extended the GW analysis method of Alexander et al. (2008) to three dimensions to estimate the complete set of GW parameters (including momentum flux and horizontal propagation direction) from the GW temperature perturbations thus derived. To demonstrate the effectiveness of the analysis, we showed global estimates of GW temperature amplitudes, vertical and horizontal wavelengths, intrinsic frequency, and vertical flux of horizontal momentum in the altitude range of 17.5-22.5 km during December 2006 to February 2007. Consistent with many previous studies, GW temperature amplitudes are a maximum in the tropics and are generally larger over land, likely reflecting convection and topography as main GW sources. GW vertical wavelengths are a minimum at equator, likely due to wave refraction, whereas GW horizontal wavelengths are generally longer in the tropics. Most of the waves captured in the analysis of the GPS data are low-intrinsic frequency inertia-GWs, and the estimated intrinsic frequencies scaled by the Coriolis parameter also show a strong maximum at equator. Enhanced wave fluxes are linked to convection, topography, and storm tracks, among others. As preliminary tests of the analysis in deriving horizontal propagation directions, we compared the GPS estimates with the corresponding estimates from the U.S. high vertical resolution radiosonde data using the conventional Stokes parameters method and we also conducted a separate analysis of the GPS data over the southern Andes in South America. We also showed the first global estimates of GW propagation directions from the GPS data. Finally, the sensitivity of the analysis to the temporal and spatial dimensions of the longitude × latitude × time cells and the uncertainties of the analysis and possible ways to reduce these uncertainties are discussed.Citation: Wang, L., and M. J. Alexander (2010), Global estimates of gravity wave parameters from GPS radio occultation temperature data,

The MaCWAVE/MIDAS rocket campaign occurred at the Andøya Rocket Range (69°N,16°E) on July 1–2 and 4–5, 2002. This paper investigates gravity waves in the mesosphere using falling spheres dropped from rockets and the Weber sodium lidar at the ALOMAR observatory. The vertical displacement of a sodium sporadic layer on July 5 showed great variability at periods from minutes to hours with an observed frequency spectral slope of −1.89. The 2 salvos had similar wave amplitudes at the mesopause, whereas Salvo 2 had stronger amplitudes in the lower atmosphere. The dominant wave period varied strongly with height, possibly due to wave breaking on the strong mean gradients or oblique propagation of wave packets. One long‐period wave appeared to propagate vertically from 75–95 km with a reduction of its vertical wavelength consistent with the mean wind gradient, but it is unclear whether it was a single wave or a superposition of waves.

Abstract. Falling sphere and balloon wind and temperature data from the MaCWAVE winter campaign, which was conducted in northern Scandinavia during January 2003, are analyzed to investigate gravity wave characteristics in the stratosphere and mesosphere. There were two stratospheric warming events occurring during the campaign, one having a maximum temperature perturbation at ∼45 km during 17-19 January, and the other having a maximum perturbation at ∼30 km during 24-27 January. The former was a major event, whereas the latter was a minor one. Both warmings were accompanied by upper mesospheric coolings, and during the second warming, the upper mesospheric cooling propagated downward. Falling sphere data from the two salvos on 24-25 January and 28 January were analyzed for gravity wave characteristics. Gravity wave perturbations maximized at ∼45-50 km, with a secondary maximum at ∼60 km during Salvo 1; for Salvo 2, wave activity was most pronounced at ∼60 km and above.Gravity wave horizontal propagation directions are estimated using the conventional hodographic analysis combined with the S-transform (a Gaussian wavelet analysis method). The results are compared with those from a Stokes analysis. They agree in general, though the former appears to provide better estimates for some cases, likely due to the capability of the S-transform to obtain robust estimates of wave amplitudes and phase differences between different fields.For Salvo 1 at ∼60 km and above, gravity waves propagated towards the southeast, whereas for Salvo 2 at similar altitudes, waves propagated predominantly towards the northwest or west. These waves were found not to be toCorrespondence to: L. Wang (lwang@cora.nwra.com) pographic waves. Gravity wave motions at ∼45-50 km in Salvo 1 were more complicated, but they generally had large amplitudes, short vertical scales, and their hodographs revealed a northwest-southeast orientation. In addition, the ratios between wave amplitudes and intrinsic phase speeds generally displayed a marked peak at ∼45-50 km and decreased sharply at ∼50 km, where the background winds were very weak. These results suggest that these wave motions were most likely topographic waves approaching their critical levels. Waves were more nearly isotropic in the lower stratosphere.

[1] We analyzed Mars Odyssey (ODY) and Mars Global Surveyor (MGS) accelerometer density retrievals in narrow local-time (LT) bands during their respective aerobraking phases to study the large-scale longitudinal density variations in the Martian upper atmosphere. The ODY data and three seasons of MGS data (fall, winter, and spring) all displayed large zonal variations in density (especially wave-2 and 3) with little vertical phase variation, consistent with previous studies using MGS aerobraking data. The large-scale density structures were most likely nonmigrating tides sampled at specific LTs. The wave-2 modes observed in the ODY and MGS data were approximately out of phase, and their respective LT samplings were approximately 12 hours apart. This reinforces the conclusion from previous studies that this mode is most likely an eastward-propagating diurnal Kelvin wave of zonal wave-1, which is produced by the interaction of the diurnal thermal forcing and the wave-2 component of the Martian topography. We also note a close association of enhanced gravity wave variances with the strong longitudinal variations in the large-scale densities, suggesting the possibility of tidal filtering of the gravity wave (GW) field.

[1] Combining data taken during the MaCWAVE summer rocket campaign at the Andøya Rocket Range (69.3°N, 16.0°E) with a lidar, radiosondes, falling spheres, and VHF radars at Andøya and at the Esrange, the gravity wave content of the troposphere and stratosphere during the campaign nights was analyzed. The lidar yielded vertical wavelengths and periods of gravity waves in the stratosphere. A Stokes parameter analysis was performed for the radiosonde and falling sphere data to estimate propagation directions of the gravity waves. The wave content in the troposphere was inferred by applying wavelet and cross-spectral methods to the radar data. We found propagation conditions and spectra of the waves to vary with height following the change in the background wind. The waves were excited both at the ground and in the tropopause/lower stratosphere region.