Characterisation of quasi-stationary planetary waves in the Northern MLT during summer

Stray, Nora H.; Espy, P. J.; Limpasuvan, Varavut; Hibbins, R. E.

doi:10.1016/j.jastp.2014.12.003

Cited by 8 publications

(8 citation statements)

References 24 publications

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“…Most of the gravity waves dissipate below the stratosphere during late summer or fall season due to strong wind shear at lower stratosphere [e.g., Tsuda et al , ; Yamashita et al , ; Hoffmann et al , ]. Planetary waves in the Northern Hemisphere are also weaker during summer and fall seasons and are mostly attributed to interhemispheric propagation [ Smith et al , ; Day and Mitchell , ; Sassi et al , ; Stray et al , ]. The influence of these local factors from stratosphere to lower mesosphere could be assessed from the MERRA‐based local winds.…”

Section: Discussionmentioning

confidence: 99%

Quasi‐biennial oscillation modulation of the middle‐ and high‐latitude mesospheric semidiurnal tides during August–September

Laskar¹,

Chau²,

Stober³

et al. 2016

JGR Space Physics

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The seasonal and interannual variabilities of mesospheric semidiurnal tides (SDT) are investigated using specular meteor radar‐based winds. The horizontal wind observations during 2003 to 2014 from a high‐latitude station, Andenes (69°N, 16°E), and during 2008 to 2014 from a midlatitude station, Juliusruh (54°N, 13°E), are used. It has been observed that the amplitudes of mesospheric SDTs are enhanced at both stations during August–September of all the years. These enhancements show a systematic behavior with that of the low‐latitude stratospheric quasi‐biennial oscillation (QBO), which is characterized based on winds from radiosonde data. The SDT amplitude values during enhancement are below/above mean level for those years in which the QBO wind at 50 hPa is westward/eastward (QBOw/QBOe). The average SDT amplitudes during the August–September enhancement duration are found to vary hand in hand with the low‐latitude QBO wind, suggesting QBO modulation of SDT. Stratospheric and lower mesospheric zonal wind perturbations from MERRA reanalysis data show weak local forcing in the Northern Hemisphere and indication of enhanced quasi‐stationary planetary waves (SPW) in the Southern Hemisphere. Based on these observations and some earlier results, we hypothesize that the QBOw/QBOe wind damp/enhance the southern hemispheric SPW of wave number 1 (SPW1). This modulated SPW1 then interacts with the northern midlatitude and high‐latitude SDTs to imprint the signature of QBO on them.

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Section: Discussionmentioning

confidence: 99%

Quasi‐biennial oscillation modulation of the middle‐ and high‐latitude mesospheric semidiurnal tides during August–September

Laskar¹,

Chau²,

Stober³

et al. 2016

JGR Space Physics

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“…The amplitude and phase of planetary‐scale tidal winds can be obtained by fitting daily winds as a function of longitude. By similar fitting techniques, observations from the same eight SuperDARN stations have been used to infer PW climatology and variability (Kleinknecht et al., 2014; Stray et al., 2015a, 2015b). Here, we utilize the derived SuperDARN data between 1995 and 2016, as in Hibbins et al.…”

Section: Methodsmentioning

confidence: 99%

Climatological Westward‐Propagating Semidiurnal Tides and Their Composite Response to Sudden Stratospheric Warmings in SuperDARN and SD‐WACCM‐X

et al. 2021

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Using the Super Dual Auroral Radar Network observations (clustered around 60°N) and NCAR CESM2.0 extended Whole Atmosphere Community Climate Model nudged with reanalyzes, we examine the climatology of semidiurnal tides in meridional wind associated with the migrating component (SW2) and non‐migrating components of wavenumbers 1 (SW1) and 3 (SW3). We then illustrate their composite response to major sudden stratospheric warmings (SSWs). Peaking in late summer and winter, the climatological SW2 amplitude exceeds SW1 and SW3 except around late Fall and Spring. The winter climatological peak is absent in the model perhaps due to the zonal wind bias at the observed altitudes. The observed SW2 amplitude declines after SSW onset before enhancing ∼10 days later, along with SW1 and SW3. Within the observed region, the simulated SW2 only amplifies after SSW onset, with minimal SW1 and SW3 responses. The model reveals a stronger SW2 response above the observed location, with diminished amplitude before and enhancement after SSW globally. This enhancement appears related to increased equatorial ozone heating and background wind symmetry. The strongest SW1 and SW3 growth occurs in the Southern Hemisphere before SSW. SW2 and quasi‐stationary planetary wave activities are temporally collocated during SSW suggesting that their interactions excite SW1 and SW3. After SSW, the model also reveals (1) semidiurnal‐tide‐like perturbations generated possibly by the interactions between SW2 and westward‐traveling disturbances and (2) the enhancement of migrating semidiurnal lunar tide in the Northern Hemisphere that exceeds non‐migrating tidal and semidiurnal‐tide‐like responses. The simulated eastward‐propagating semidiurnal tides are briefly examined.

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“…Kleinknecht et al () demonstrated that concurrent horizontal wind data associated with the meteor drift observed by SuperDARN radars could be used to derive the various PW components (zonal wavenumbers 1 and 2) in the MLT at these latitudes. Climatologies (Kleinknecht et al, ) and studies of PW variability during summer (Stray, Espy, et al, ), the autumn equinox (Stray et al, ), and during SSWs (Stray, Orsolini, et al, ) were presented using SuperDARN data recorded between 2000 and 2008.…”

Section: Introductionmentioning

confidence: 99%

SuperDARN Observations of Semidiurnal Tidal Variability in the MLT and the Response to Sudden Stratospheric Warming Events

et al. 2019

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Using meteor wind data from the Super Dual Auroral Radar Network (SuperDARN) in the Northern Hemisphere, we (1) demonstrate that the migrating (Sun‐synchronous) tides can be separated from the nonmigrating components in the mesosphere and lower thermosphere (MLT) region and (2) use this to determine the response of the different components of the semidiurnal tide (SDT) to sudden stratospheric warming (SSW) conditions. The radars span a limited range of latitudes around 60°N and are located over nearly 180° of longitude. The migrating tide is extracted from the nonmigrating components observed in the meridional wind recorded from meteor ablation drift velocities around 95‐km altitude, and a 20‐year climatology of the different components is presented. The well‐documented late summer and wintertime maxima in the semidiurnal winds are shown to be due primarily to the migrating SDT, whereas during late autumn and spring the nonmigrating components are at least as strong as the migrating SDT. The robust behavior of the SDT components during SSWs is then examined by compositing 13 SSW events associated with an elevated stratopause recorded between 1995 and 2013. The migrating SDT is seen to reduce in amplitude immediately after SSW onset and then return anomalously strongly around 10–17 days after the SSW onset. We conclude that changes in the underlying wind direction play a role in modulating the tidal amplitude during the evolution of SSWs and that the enhancement in the midlatitude migrating SDT (previously reported in modeling studies) is observed in the MLT at least up to 60°N.

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Characterisation of quasi-stationary planetary waves in the Northern MLT during summer

Cited by 8 publications

References 24 publications

Quasi‐biennial oscillation modulation of the middle‐ and high‐latitude mesospheric semidiurnal tides during August–September

Quasi‐biennial oscillation modulation of the middle‐ and high‐latitude mesospheric semidiurnal tides during August–September

Climatological Westward‐Propagating Semidiurnal Tides and Their Composite Response to Sudden Stratospheric Warmings in SuperDARN and SD‐WACCM‐X

SuperDARN Observations of Semidiurnal Tidal Variability in the MLT and the Response to Sudden Stratospheric Warming Events

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