[1] We present periodic variations of the migrating diurnal tide from Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics (TIMED) temperature and wind data from 2002 to 2007 and meteor radar data at Maui (20.75°N, 156.43°W). There are strong quasi-biennial oscillation (QBO) signatures in the amplitude of the diurnal tidal temperature in the tropical region and in the wind near ±20°. The magnitude of the QBO in the diurnal tidal amplitude reaches about 3 K in temperature and about 7 m/s (Northern Hemisphere) and 9 m/s (Southern Hemisphere) in meridional wind. The period of the diurnal tide QBO is around 24-25 months in the mesosphere but is quite variable with altitude in the stratosphere. Throughout the mesosphere, the amplitude of the diurnal tide reaches maximum during March/April of years when the QBO in lower stratospheric wind is in the eastward phase. Because the tide shows amplification only during a limited time of the year, there are not enough data yet to determine whether the tidal variation is truly biennial (24-month period) or is quasi-biennial. The semiannual (SAO) and annual oscillations (AO) in the diurnal tide support previous findings: tidal amplitude is largest around equinoxes (SAO signal) and is larger during the vernal equinox (AO signal). TIMED Sounding of the Atmosphere using Broadband Emission Radiometry (TIMED/SABER) temperature and atmospheric pressure data are used to calculate the balance wind and the tides in horizontal wind. The comparison between the calculations and the wind observed by TIMED Doppler Interferometer (TIDI) and meteor radar indicates qualitative agreement, but there are some differences as well.

In this work, 11 years (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012) of Thermosphere, Ionosphere, Mesosphere Energetics, and Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) global temperature data are used to study the nonlinear interaction between stationary planetary waves (SPWs) and tides in the stratosphere and mesosphere. The holistic behavior of the nonlinear interactions between all SPWs and tides is analyzed from the point of view of energetics. The results indicate that the intensities of nonmigrating diurnal, semidiurnal, terdiurnal, and 6 h tides are strongest during winter and almost vanish during summer, synchronous with SPW activity. Temporal correlations between the SPWs and nonmigrating tides for these four tidal components are strong in the region poleward of 20°and below about 80 km. In the tropics, where the SPWs are very weak in all seasons, the correlations are small. Bispectral analysis between triads of waves and tides shows which particular interactions are likely to be responsible for the generation of the nonmigrating tides that are largest in the midlatitude stratosphere. Based on the more limited SABER observations at high latitudes, the correlations there are similar to those in midlatitudes during spring, summer, and autumn; there are no high-latitude observations by SABER in winter. These results show that nonlinear interactions between SPWs and tides in the stratosphere and the lower mesosphere may be an important source of the nonmigrating tides that then propagate into the upper mesosphere and lower thermosphere.

[1] Airglow from the hydroxyl Meinel bands, originating from about 87 km, gives a signature of the atmosphere that can be observed remotely. Analysis of long term global observations of the 2.0 mm OH Meinel brightness observed by the TIMED/SABER satellite instrument presents some striking patterns that appear in the Meinel airglow. The analysis shows that migrating and nonmigrating tides have large effects on the nighttime OH airglow emission in the upper mesosphere. The OH airglow emission rate is positively correlated with temperature below 94 km and negatively correlated above. Variations with longitudinal wavenumbers 1 and 4 are shown to result from the impacts of the stationary (D0), westward wavenumber 2 (DW2), and eastward wavenumber 3 (DE3) nonmigrating diurnal tides. Citation:

[1] In this paper, observations by thermosphere, ionosphere, mesosphere energetics and dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry from 2002 to 2012 and by Envisat/Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) from 2008 to 2009 are used to study the longitudinal structure of temperature in the lower thermosphere. In order to remove the longitudinal structure induced by tides, diurnally averaged SABER temperatures are used. For MIPAS data, we use averaged temperatures between day and night. The satellite observations show that there are strong longitudinal variations in temperature in the high-latitude lower thermosphere that persist over all seasons. The peak of the diurnally averaged temperature in the lower thermosphere always occurs around the auroral zone. A clear asymmetry between the two hemispheres in the longitudinal temperature structure is observed, being more pronounced in the Southern than in the Northern Hemisphere. In both hemispheres, the longitudinal variation is dominated by the first harmonic in longitude. The total radiative cooling observed by SABER has a structure in longitude that is similar to that of temperature. Modeling simulations using the Thermosphere-Ionosphere-Electrodynamics General Circulation Model reproduce similar features of the longitudinal variations of temperature in the lower thermosphere. Comparison of two model runs with and without auroral heating confirms that auroral heating causes the observed longitudinal variations. The multiyear averaged vertical structures of temperature observed by the two satellite instruments indicate that the impact of auroral heating on the thermodynamics of the neutral atmosphere can penetrate down to about 105 km.

In this paper, analysis of wind data detected by six ground‐based radar systems located in equatorial and midlatitude belts shows that a strong mesospheric 6.5‐day wave event occurred during April–May 2003. We compared the global distribution of the observed 6.5‐day wave event with the theoretical wave structure (Rossby normal mode (s, n) = (1, −2)). Additionally, we investigated several important wave characteristics to understand the mesospheric 6.5‐day wave event, i.e., wave period, vertical structure, relationship with background wind, propagating direction, and the zonal wave number. Our results are summarized into three points: (1) the latitudinal structure of the mesospheric 6.5‐day wave during April–May 2003 is basically in agreement with the theoretical Rossby mode (s, n) = (1, −2), although the wave amplitude of zonal wind peaked at the subequatorial latitude of Northern Hemisphere but not at the theoretical place, equatorial region; (2) the main wave periods and the altitude distribution of large amplitude of this wave event varied with latitude; (3) the downward propagating wave phases indicated that this wave event originated in the lower atmosphere and propagated upward to the upper region.

No abstract

No abstract

A Fabry-Perot interferometer, funded by the Meridian Project in China, was deployed at the Xinglong station (40. 2°N,117.4°E) of the National Astronomical Observatories in Hebei Province, China. The instrument has been operating since April 2010, measuring mesospheric and thermospheric winds. The first observational data of winds at three heights in the mesosphere and thermosphere were analyzed, demonstrating the capacity of this instrument to aid basic scientific research. The wavelengths of three airglow emissions were OH892.0, OI 557.7, and OI 630.0 nm, which corresponded to heights of 87, 98, and 250 km, respectively. Three 38-day data sets of horizontal winds, from April 5, 2010 to May 12, 2010, show clear day-to-day variations at the same height. The minimum and maximum meridional winds at heights of 87, 98, and 250 km were -16.5 to 8.7 m/s, -24.4 to 15.9 m/s, and -43.6 to 1.5 m/s. Measurements of zonal winds were -5.4 to 7.6 m/s, 2.3 to 23.0 m/s, and -22.6 to 49.3 m/s. The average data from the observations was consistent with the data from HWM93. The wind data at heights of 87 and 98 km suggest a semi-diurnal oscillation, clearly consistent with HWM93 results. Conversely there was a clear discrepancy between the observations and the model at 250 km. In general, this Fabry-Perot interferometer is a useful ground-based instrument for measuring mesospheric and thermospheric winds at middle latitudes. Fabry-Perot interferometer, mesopause, thermosphere, airglows, windsCitation: Yuan W, Xu J Y, Ma R P, et al. First observation of mesospheric and thermospheric winds by a Fabry-A Fabry-Perot Interferometer (FPI) uses a CCD detector to record interference patterns formed by the Fabry-Perot etalon filter. Interference patterns provide much information, such as Doppler shift and spectrum line broadening. FPIs have been used for many years worldwide to measure neutral winds and temperatures in the mesosphere and thermosphere as both ground-based and satellite-borne instruments [1-5]. Neutral winds can be derived from monitoring the night time airglow emissions of OH 892.0 nm at 87 km, OI 557.7 nm at 98 km, and OI 630.0 nm at 250 km. These observational neutral wind data are important for modeling