Meteor wind radar observations of gravity wave momentum fluxes and their forcing toward the Mesospheric Semiannual Oscillation

Antonita, T. Maria; Ramkumar, Geetha; Kumar, Karanam Kishore; Deepa, V.

doi:10.1029/2007jd009089

Cited by 60 publications

(61 citation statements)

References 66 publications

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“…At the quasi-equatorial location the semi-annual variation in the fluctuating wind is less pronounced than at the other locations, although the variation in the meridional component of the diurnal tide is not much different. These seasonal variations seen at Cariri are consistent with those found by Antonita et al (2008) for another equatorial site (Trivandrum,8.5 • N). For all the locations the zonal winds, both tidal and fluctuating, are smaller than the meridional, and show less regular seasonal effects.…”

Section: Resultssupporting

confidence: 79%

“…If, as has been suggested both by modeling studies (Mayr et al, 2001;Ortland and Alexander, 2006) and observations (Reid and Vincent 1987;Antonita et al, 2008), that the deposition of momentum by gravity waves contributes to the mean flow, then we should expect to see a correlation between the fluctuating wind velocity and the (mainly tidal) background wind. We investigate this in Fig.…”

Section: Resultsmentioning

confidence: 99%

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Seasonal variations in gravity wave activity at three locations in Brazil

et al. 2009

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Abstract. Using the variance in meteor radar winds as a measure of gravity wave activity, we investigate the temporal variations in gravity waves at three locations in Brazil: São João do Cariri (2005) which makes it possible to separate the zonal and meridional components of the fluctuating wind velocity. We find that the seasonal variation of the fluctuating wind is similar to that of the amplitude of the diurnal tide, showing a predominantly semi-annual variation, stronger at Cachoeira Paulista and Santa Maria than at the quasi-equatorial station, Cariri. Both with respect to the seasonal trend and shorter term variations, strong coupling between gravity wave activity and tides is indicated by a remarkably close correlation between the fluctuating velocity and the vertical shear in the tidal winds. It is not clear as to whether this is caused by gravity wave forcing of the tides or whether it results from in situ generation of gravity waves by tidal wind shear.

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Section: Resultssupporting

confidence: 79%

Section: Resultsmentioning

confidence: 99%

Seasonal variations in gravity wave activity at three locations in Brazil

et al. 2009

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“…Placke et al (2011b) in their analysis of GW activity over Andenes (69.3 • N, 16 • E) and Juliusruh (54.6 • N, 13.4 • E) report SAO with maxima around the solstice. As stated earlier, annual and semiannual oscillations in GW activity are anticipated and have been documented in earlier work (e.g., Antonita et al,2008;Clemesha et al, 2009;Mitchell and Beldon, 2009;Beldon and Mitchell, 2009;Senft and Gardner, 1991;Placke et al, 2011b;De Wit et al, 2014b; and references therein); however, this appears to be the first report of a 4-month oscillation in GW momentum fluxes.…”

Section: Discussionmentioning

confidence: 87%

“…10). Antonita et al (2008), also using Hocking's analysis, found a SAO for the GW momentum fluxes with maxima at the equinoxes, over Trivandrum (8.5 • N, 76.9 • E). In the present study, no statically significant SAO in momen- tum fluxes has been observed.…”

Section: Discussionmentioning

confidence: 99%

“…In recent years the results of a number of studies have been published using the Hocking technique, e.g., Antonita et al (2008), Fritts et al (2010Fritts et al ( , 2012a, Placke et al (2011a, b), Andrioli et al (2013a, b) and de Wit et al (2014a, b). Andrioli et al (2013a) described a method for using the technique in composite days with the purpose of maximizing the number of available meteor echoes and thus allowing the investigation of momentum fluxes using simple meteor radars with improved accuracy and with no contamination by tides and planetary waves.…”

Section: Introductionmentioning

confidence: 99%

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Multi-year observations of gravity wave momentum fluxes at low and middle latitudes inferred by all-sky meteor radar

et al. 2015

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• W) were used to estimate the GW momentum fluxes and variances in the MLT region. Our analysis can provide monthly mean altitude profiles of vertical fluxes of horizontal momentum for short-period (less than 2-3 h) GWs. The averages for each month throughout the entire data series have shown different behavior for the momentum fluxes depending on latitude and component. The meridional component has almost the same behavior at the three sites, being positive (northward), for most part of the year. On the other hand, the zonal component shows different behavior at each location: it is positive for almost half the year at Cariri and SM but predominantly negative over CP. Annual variation in the GW momentum fluxes is present at all sites in the zonal component and also in SM at 89 km in the meridional component. The seasonal analysis has also shown a 4-month oscillation at 92.5 km over SM in the zonal component and over CP at the same altitudes but for the meridional component.

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Gravity wave momentum fluxes from MF and meteor radar measurements in the polar MLT region

et al. 2015

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Annual cycles of horizontal winds and gravity wave (GW) momentum fluxes in the mesosphere/lower thermosphere (MLT) are presented for the medium frequency Doppler radar at Saura (SMF radar, located at 69°N, 16°E) for the first time. Four year mean wind and momentum flux fields for 2008 through 2011 clearly show the coupling and interactions between GWs and the mean flow especially in the summer months. GW breaking at mesopause heights results in momentum flux divergence and affects the wind field by forcing a reversal of the wind profile in summer. Height‐time cross sections for the individual years (2008 to 2011) illustrate the year‐to‐year variation of horizontal winds and the vertical fluxes of zonal and meridional momentum. They show similar annual patterns from year to year which are more consistent in the summer months than during winter and have maximum absolute values in 2009. Furthermore, the precise SMF radar measurements give an excellent possibility to evaluate momentum flux estimates from the colocated meteor radar at Andenes. Both radars have different capabilities, and different techniques are applied to derive momentum fluxes. They show comparable results for the 4 year mean annual cycles of horizontal winds and momentum fluxes especially in summer. This holds for both structure and magnitudes in the overlapping heights, where the SMF radar data provide a wider vertical coverage. The best agreement is found for the zonal components of both radars, whereas there are some larger discrepancies in the meridional components, especially in the vertical flux of meridional momentum.

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Meteor wind radar observations of gravity wave momentum fluxes and their forcing toward the Mesospheric Semiannual Oscillation

Cited by 60 publications

References 66 publications

Seasonal variations in gravity wave activity at three locations in Brazil

Seasonal variations in gravity wave activity at three locations in Brazil

Multi-year observations of gravity wave momentum fluxes at low and middle latitudes inferred by all-sky meteor radar

Gravity wave momentum fluxes from MF and meteor radar measurements in the polar MLT region

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