Aura MLS observations of the westward-propagating &amp;lt;i&amp;gt;s&amp;lt;/i&amp;gt;=1, 16-day planetary wave in the stratosphere, mesosphere and lower thermosphere

Day, K. A.; Hibbins, R. E.; Mitchell, N. J.

doi:10.5194/acp-11-4149-2011

Cited by 56 publications

(80 citation statements)

References 40 publications

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“…There is also an oscillation of period ∼16 days and amplitudes of order ∼15 m s −1 and 10 K in December and January, similarly marked on the figure. These periods are consistent with those reported for the "5-day wave" and the "16-day wave", respectively (e.g., Espy and Witt, 1996;Espy et al, 1997;Luo et al, 2002b;Lieberman et al, 2003;Riggin et al, 2006;Day and Mitchell, 2010a,b;Day et al, 2011).…”

Section: -And 5-day Planetary Wavessupporting

confidence: 80%

“…SSWs are known to dampen planetarywave amplitudes about one month after the SSW has occurred. This has been reported in a number of studies, (e.g., Alexander and Shepherd, 2010;Day et al, 2011).…”

Section: Atmosmentioning

confidence: 79%

“…Williams and Avery, 1992;Forbes et al, 1995;Day and Mitchell, 2010b). The 5-day wave has been reported to have wind amplitudes of up to about ∼20 m s −1 and temperature amplitudes reaching ∼15 K in the MLT (e.g.…”

Section: K a Day Et Al: Mean Winds Temperatures And The 16-and 5-dmentioning

confidence: 99%

“…This method has been used by a number of other studies (e.g., Limpasuvan et al, 2005;Baumgaertner et al, 2008;Limpasuvan and Wu, 2009;McDonald et al, 2011;Day et al, 2011). The uncertainty in the wave amplitude estimated using this method is usually ± 0.6 K or smaller, e.g., Day et al (2011). In this analysis the temperature data were sorted into 10 • latitude bands and the leastsquares fitting of a westward-propagating zonal wavenumber 1 wave was applied to the monthly data within each latitude band.…”

Section: Atmosmentioning

confidence: 99%

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Mean winds, temperatures and the 16- and 5-day planetary waves in the mesosphere and lower thermosphere over Bear Lake Observatory (42° N, 111° W)

2012

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Abstract. Atmospheric temperatures and winds in the mesosphere and lower thermosphere have been measured simultaneously using the Aura satellite and a meteor radar at Bear Lake Observatory (42 • N, 111 • W), respectively. The data presented in this study is from the interval March 2008 to July 2011.The mean winds observed in the summer-time over Bear Lake Observatory show the meridional winds to be equatorward at meteor heights during April-August and to reach monthly-mean velocities of −12 m s −1 . The mean winds are closely related to temperatures in this region of the atmosphere and in the summer the coldest mesospheric temperatures occur about the same time as the strongest equatorward meridional winds. The zonal winds are eastward through most of the year and in the summer strong eastward zonal wind shears of up to ∼4.5 m s −1 km −1 are present. However, westward winds are observed at the upper heights in winter and sometimes during the equinoxes. Considerable inter-annual variability is observed in the mean winds and temperatures.Comparisons of the observed winds with URAP and HWM-07 reveal some large differences. Our radar zonal wind observations are generally more eastward than predicted by the URAP model zonal winds. Considering the radar meridional winds, in comparison to HWM-07 our observations reveal equatorward flow at all meteor heights in the summer whereas HWM-07 suggests that only weakly equatorward, or even poleward flows occur at the lower heights. However, the zonal winds observed by the radar and modelled by HWM-07 are generally similar in structure and strength.Signatures of the 16-and 5-day planetary waves are clearly evident in both the radar-wind data and Aura-temperature data. Short-lived wave events can reach large amplitudes of up to ∼15 m s −1 and 8 K and 20 m s −1 and 10 K for the 16-and 5-day waves, respectively. A clear seasonal and shortterm variability are observed in the 16-and 5-day planetary wave amplitudes. The 16-day wave reaches largest amplitude in winter and is also present in summer, but with smaller amplitudes. The 5-day wave reaches largest amplitude in winter and in late summer. An inter-annual variability in the amplitude of the planetary waves is evident in the four years of observations. Some 41 episodes of large-amplitude wave occurrence are identified. Temperature and wind amplitudes for these episodes, A T and A W , that passed the Student T-test were found to be related by, A T = 0.34 A W and A T = 0.62 A W for the 16-and 5-day wave, respectively.

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Section: -And 5-day Planetary Wavessupporting

confidence: 80%

Section: Atmosmentioning

confidence: 79%

Section: K a Day Et Al: Mean Winds Temperatures And The 16-and 5-dmentioning

confidence: 99%

Section: Atmosmentioning

confidence: 99%

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Mean winds, temperatures and the 16- and 5-day planetary waves in the mesosphere and lower thermosphere over Bear Lake Observatory (42° N, 111° W)

2012

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“…The maximum in both data sets is up to 270 K 2 around 50 to 60 • N/S. The activity of planetary waves is weaker in the Southern Hemisphere winter, and in the Southern Hemisphere the polar vortex is more invariant than in the Northern Hemisphere (e.g., Day et al, 2011). This is represented by the background variances, which are larger in Northern Hemisphere winter than in Southern Hemisphere winter.…”

Section: Removal Of Background Signals To Extract Gravity Wave Informmentioning

confidence: 87%

Intercomparison of AIRS and HIRDLS stratospheric gravity wave observations

Meyer¹,

Ern²,

Hoffmann³

et al. 2018

Atmos. Meas. Tech.

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Abstract. We investigate stratospheric gravity wave observations by the Atmospheric InfraRed Sounder (AIRS) aboard NASA's Aqua satellite and the High Resolution Dynamics Limb Sounder (HIRDLS) aboard NASA's Aura satellite. AIRS operational temperature retrievals are typically not used for studies of gravity waves, because their vertical and horizontal resolution is rather limited. This study uses data of a high-resolution retrieval which provides stratospheric temperature profiles for each individual satellite footprint. Therefore the horizontal sampling of the high-resolution retrieval is 9 times better than that of the operational retrieval. HIRDLS provides 2-D spectral information of observed gravity waves in terms of along-track and vertical wavelengths. AIRS as a nadir sounder is more sensitive to short-horizontal-wavelength gravity waves, and HIRDLS as a limb sounder is more sensitive to short-vertical-wavelength gravity waves. Therefore HIRDLS is ideally suited to complement AIRS observations. A calculated momentum flux factor indicates that the waves seen by AIRS contribute significantly to momentum flux, even if the AIRS temperature variance may be small compared to HIRDLS. The stratospheric wave structures observed by AIRS and HIRDLS often agree very well. Case studies of a mountain wave event and a non-orographic wave event demonstrate that the observed phase structures of AIRS and HIRDLS are also similar. AIRS has a coarser vertical resolution, which results in an attenuation of the amplitude and coarser vertical wavelengths than for HIRDLS. However, AIRS has a much higher horizontal resolution, and the propagation direction of the waves can be clearly identified in geographical maps. The horizontal orientation of the phase fronts can be deduced from AIRS 3-D temperature fields. This is a restricting factor for gravity wave analyses of limb measurements. Additionally, temperature variances with respect to stratospheric gravity wave activity are compared on a statistical basis. The complete HIRDLS measurement period from January 2005 to March 2008 is covered. The seasonal and latitudinal distributions of gravity wave activity as observed by AIRS and HIRDLS agree well. A strong annual cycle at mid-and high latitudes is found in time series of gravity wave variances at 42 km, which has its maxima during wintertime and its minima during summertime. The variability is largest during austral wintertime at 60 • S. Variations in the zonal winds at 2.5 hPa are associated with large variability in gravity wave variances. Altogether, gravity wave variances of AIRS and HIRDLS are complementary to each other. Large parts of the gravity wave spectrum are covered by joint observations. This opens up fascinating vistas for future gravity wave research.

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Interannual variability of mesopause zonal winds over Ascension Island: Coupling to the stratospheric QBO

et al. 2013

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[1] Zonal-wind measurements obtained between October 2001 and July 2011 with the SKiYMET meteor radar located at Ascension Island (8 ı S, 14 ı W) have been used to study the interannual variability at meteor ablation altitudes (approximately 78-100 km) and its coupling to the stratospheric quasi-biennial oscillation (QBO). An upper mesospheric QBO (MQBO) with a period of 27.5 months has been detected throughout the observational period. The MQBO is found to be out-of-phase with the stratospheric QBO (SQBO) at 15-20 hPa and in-phase compared to 70 hPa, whereas no significant zero time-lag correlation exists between the long-term mesospheric zonal winds and the SQBO at 40-50 hPa. The MQBO magnitude is found to be 4.1˙0.7 m/s at 88 km. No significant change in MQBO magnitude is found throughout the altitude range under consideration. It was found that the MQBO signal is mainly carried around the March equinox, although the MQBO signal is present throughout most of the year, although less pronounced, at the lower altitudes as well. No observational evidence was found that the MQBO, between approximately 78-100 km, plays a role in the interhemispheric ducting of the quasi-16 day wave.

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Aura MLS observations of the westward-propagating <i>s</i>=1, 16-day planetary wave in the stratosphere, mesosphere and lower thermosphere

Cited by 56 publications

References 40 publications

Mean winds, temperatures and the 16- and 5-day planetary waves in the mesosphere and lower thermosphere over Bear Lake Observatory (42° N, 111° W)

Mean winds, temperatures and the 16- and 5-day planetary waves in the mesosphere and lower thermosphere over Bear Lake Observatory (42° N, 111° W)

Intercomparison of AIRS and HIRDLS stratospheric gravity wave observations

Interannual variability of mesopause zonal winds over Ascension Island: Coupling to the stratospheric QBO

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