[1] In this work absolute values of gravity wave (GW) momentum flux are derived from global temperature measurements by the satellite instruments High Resolution Dynamics Limb Sounder (HIRDLS) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER). Momentum fluxes in the stratosphere are derived for both instruments and for SABER in the whole mesosphere. The large-scale atmospheric background state is removed by a two-dimensional Fourier decomposition in longitude and time, covering even planetary-scale waves with periods as short as 1-2 days. Therefore, it is possible to provide global distributions of GW momentum flux from observations for the first time in the mesosphere. Seasonal as well as longer-term variations of the global momentum flux distribution are discussed. GWs likely contribute significantly to the equatorward tilt of the polar night jet and to the poleward tilt of the summertime mesospheric jet. Our results suggest that GWs can undergo large latitudinal shifts while propagating upward. In particular, GWs generated by deep convection in the subtropical monsoon regions probably contribute significantly to the mesospheric summertime wind reversal at mid-and high latitudes. Variations in the GW longitudinal distribution caused by those convectively generated GWs are still observed in the mesosphere and could be important for the generation of the quasi two-day wave. Indications for quasi-biennial oscillation (QBO) induced variations of GW momentum flux are found in the subtropics. Also variations at time scales of about one 11-year solar cycle are observed and might indicate a negative correlation between solar flux and GW momentum flux.Citation: Ern, M., P. Preusse, J. C. Gille, C. L. Hepplewhite, M. G. Mlynczak, J. M. Russell III, and M. Riese (2011), Implications for atmospheric dynamics derived from global observations of gravity wave momentum flux in stratosphere and mesosphere,
[1] Coupling between the troposphere and lower thermosphere due to upward propagating tides is investigated using temperatures measured from the SABER instrument on the TIMED satellite. The data analyzed here are confined to 20-120 km altitude and ±40°l atitude during 20 July to 20 September 2002. Apart from the migrating (Sun-synchronous) tidal components, the predominant feature seen (from the satellite frame) during this period is a wave-4 structure in longitude with extrema of up to ±40-50 K at 110 km. Amplitudes and longitudes of maxima of this structure evolve as the satellite precesses in local time and as the wave(s) responsible for this structure vary with time. The primary wave responsible for the wave-4 pattern is the eastward propagating diurnal tide with zonal wave number s = 3 (DE3). Its average amplitude distribution over the interval is quasi-symmetric about the equator, similar to that of a Kelvin wave, with maximum of about 20 K at 5°S and 110 km. DE3 is primarily excited by latent heating due to deep tropical convection in the troposphere. It is demonstrated that existence of DE3 is intimately connected with the predominant wave-4 longitude distribution of topography and land-sea difference at low latitudes, and an analogy is drawn with the strong presence of DE1 in Mars atmosphere, the predominant wave-2 topography on Mars, and the wave-2 patterns that dominate density measurements from the Mars Global Surveyor (MGS) spacecraft near 130 km. Additional diurnal, semidiurnal, and terdiurnal nonmigrating tides are also revealed in the present study. These tidal components are most likely excited by nonlinear interactions between their migrating counterparts and the stationary planetary wave with s = 1 known to exist in the Southern Hemisphere during this period just prior to the austral midwinter stratospheric warming of 2002.
[1] Temperature observations from the SABER instrument on the TIMED spacecraft are used to investigate the structure and evolution of an eastward propagating zonal wavenumber 2 disturbance with a period near two days. This oscillation obtains a maximum amplitude of nearly 10 K in the southern hemisphere mid-latitudes during late January. The timing and location of this planetary wave is coincident with the regular quasi two-day wave intensification that occurs annually in late January. The period, wavenumber and spatial structure of the eastward propagating two-day wave are consistent with a wave that results from a nonlinear interaction between the quasi two-day wave and the migrating diurnal tide. The existence of an eastward propagating wave with a period near two days coincident with the westward propagating two day wave will have an impact on the interpretation of ground based observations. Analysis of the SABER temperature observations are utilized to determine the structure and evolution of both this eastward propagating two-day wave and the classic westward propagating zonal wavenumber 3 quasi two-day wave during January 2005. Citation: Palo, S. E., J. M. Forbes, X. Zhang, J. M. Russell III, and M. G. Mlynczak (2007), An eastward propagating two-day wave: Evidence for nonlinear planetary wave and tidal coupling in the mesosphere and lower thermosphere, Geophys. Res. Lett., 34, L07807,
We have searched the 6.8 μm water vapor radiance data obtained from the Sounding of the Atmosphere with Broadband Emission Radiometry (SABER) on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite for evidence of rocket plumes. Between 94–130 km, significant radiance enhancements are occasionally seen which correspond in time and space to emission from the exhaust plumes of the space shuttle and various unmanned liquid‐fueled rockets. Over a 10 month period in 2002 (Feb–Nov), SABER detected about 40% of the total liquid fueled launches, including four out of four space shuttle launches. The shuttle plumes are seen at and below 115 km, while the unmanned rocket plumes extend to higher altitudes. The meridional transport of the shuttle plumes near 110 km suggests a dependence upon the local time of the launch with plumes from mid‐day launches traveling to the N and plumes from late afternoon and evening launches traveling to the S.
[1] Comparisons of monthly mean nighttime temperature profiles observed by the sodium lidar at Colorado State University and TIMED/SABER overpasses are made. In the altitude range from 85 km to about 100 km, the two observations are in very good agreement. Though within each other's error bars, important differences occur below 85 km in the entire year and above 100 km in the summer season. Possible reasons for these difference are high photon noise below 85 km in lidar observations and less than accurate assumptions in the concentration of important chemical species like oxygen (and its quenching rate) in the SABER retrieval above 100 km. However, the two techniques both show the two-level mesopause thermal structure, with the times of change from one level to the other in excellent agreement. Comparison indicates that the highlevel (winter) mesopause altitudes are also in excellent agreement between the two observations, though some difference (2-3 km) may exist in the low-level (summer) mesopause altitudes between ground-based and satellite-borne data. In addition, the difference in local time dependency between lidar and SABER is investigated; this difference makes the comparison of mesopause altitudes difficult.
[1] In the zonal mean meridional winds of the upper mesosphere, oscillations with periods between 1 and 4 months have been inferred from UARS measurements and independently predicted with the Numerical Spectral Model (NSM). The wind oscillations tend to be confined to low latitudes and appear to be driven, at least in part, by wavemean-flow interactions. Winds across the equator should generate, due to dynamical heating and cooling, temperature oscillations with opposite phase in the two hemispheres. Investigating this phenomenon, we have analyzed SABER temperatures from TIMED in the altitude range between 55 and 95 km to delineate with an empirical model, the yearlong variability of the migrating tides and zonal mean components. The inferred seasonal variations of the diurnal tide, characterized by amplitude maxima near equinox, are in substantial agreement with UARS observations and results from the NSM. For the zonal mean, the dominant seasonal variations in the SABER temperatures, with annual (12 months) and semiannual (6 months) periodicities, agree well with those derived from UARS measurements. The intraseasonal variations with periods between 2 and 4 months have amplitudes close to 2 K, almost half as large as those for the dominant seasonal variations. Their amplitudes are in qualitative agreement with the corresponding values inferred from UARS during different years. The SABER and UARS temperature variations reveal pronounced hemispherical asymmetries, consistent with meridional wind oscillations across the equator. The phase of the semiannual temperature oscillations from the NSM agrees with the observations from UARS and SABER. However, the amplitudes are systematically smaller, which may indicate that planetary waves are more important than is allowed for in the model. For the shorter-period intraseasonal variations, which can be generated by gravity wave drag, the model results are generally in better agreement with the observations.
This paper discusses the solar cycle variation of the DE3 and DE2 nonmigrating tides in the nitric oxide (NO) 5.3 m and carbon dioxide (CO 2 ) 15 m infrared cooling between 100 and 150 km altitude and ±40 • latitude. Tidal diagnostics of SABER NO and CO 2 cooling rate data (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013) indicate DE3 (DE2) amplitudes during solar maximum are on the order of 1 (0.5) nW/m 3 in NO near 125 km, and on the order of 60 (30) nW/m 3 in CO 2 at 100 km, which translates into roughly 15-30% relative to the monthly zonal mean. The NO cooling shows a pronounced (factor of 10) solar cycle dependence (lower during solar minimum) while the CO 2 cooling does not vary much from solar min to solar max. Photochemical modeling reproduces the observed solar cycle variability and allows one to delineate the physical reasons for the observed solar flux dependence of the tides in the infrared cooling, particularly in terms of warmer/colder background temperature versus smaller/larger tidal temperatures during solar max/min, in addition to cooling rate variations due to vertical tidal advection and tidal density variations. Our results suggest that (i) tides caused by tropospheric weather impose a substantial-and in the NO 5.3 m case solar cycle dependent-modulation of the infrared cooling, mainly due to tidal temperature, and (ii) observed tides in the infrared cooling are a suitable proxy for tidal activity including its solar cycle dependence in a part of Earth's atmosphere where direct global temperature observations are lacking.
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