Influence of parameterized small‐scale gravity waves on the migrating diurnal tide in Earth's thermosphere

Yiğit, Erdal; Medvedev, Alexander S.

doi:10.1002/2017ja024089

Cited by 60 publications

(69 citation statements)

References 93 publications

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“…Due to the excitation process, tides have periods of 1 solar day (24 h) and its harmonics, like 12 or 8 h. The tidal propagation can be either Sun-synchronous or not, and accordingly tides are called migrating or non-migrating tides (Forbes, 1995). They modulate the background wind field together with planetary waves and therefore have an impact on the propagation conditions for gravity waves (e.g., Eckermann and Marks, 1996;Senf and Achatz, 2011;Yigit and Medvedev, 2017). Upwardpropagating GW transport energy and momentum and deposit them during their breaking and filtering to the mean background flow (Holton and Alexander, 2000;Fritts and Alexander, 2003).…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, additional data are required for validation and more observational data are nec-essary for improving these parametrizations (Geller et al, 2013). There are approaches of gravity wave parametrization schemes, which improve the structure and magnitude of tides, but a validation with observational data is still rare (Yigit et al, 2008;Yigit and Medvedev, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Temporal variability of tidal and gravity waves during a record long 10-day continuous lidar sounding

et al. 2018

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Abstract. Gravity waves (GWs) as well as solar tides are a key driving mechanism for the circulation in the Earth's atmosphere. The propagation of gravity waves is strongly affected by tidal waves as they modulate the mean background wind field and vice versa, which is not yet fully understood and not adequately implemented in many circulation models. The daylight-capable Rayleigh-Mie-Raman (RMR) lidar at Kühlungsborn (54 • N, 12 • E) typically provides temperature data to investigate both wave phenomena during one full day or several consecutive days in the middle atmosphere between 30 and 75 km altitude. Outstanding weather conditions in May 2016 allowed for an unprecedented 10-day continuous lidar measurement, which shows a large variability of gravity waves and tides on timescales of days. Using a one-dimensional spectral filtering technique, gravity and tidal waves are separated according to their specific periods or vertical wavelengths, and their temporal evolution is studied. During the measurement period a strong 24 h wave occurs only between 40 and 60 km and vanishes after a few days. The disappearance is related to an enhancement of gravity waves with periods of 4-8 h. Wind data provided by ECMWF are used to analyze the meteorological situation at our site. The local wind structure changes during the observation period, which leads to different propagation conditions for gravity waves in the last days of the measurement period and therefore a strong GW activity. The analysis indicates a further change in wave-wave interaction resulting in a minimum of the 24 h tide. The observed variability of tides and gravity waves on timescales of a few days clearly demonstrates the importance of continuous measurements with high temporal and spatial resolution to detect interaction phenomena, which can help to improve parametrization schemes of GWs in general circulation models.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Temporal variability of tidal and gravity waves during a record long 10-day continuous lidar sounding

et al. 2018

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“…Depending on their characteristics, these GWs may play important roles in both neutral thermosphere and plasma processes. For example, horizontal acceleration caused by GW momentum flux divergence from GW dissipation can result in substantial local forcing in the thermosphere, which significantly changes the neutral wind there (e.g., Vadas & Liu, ; Vadas & Nicolls, ; Vadas et al, ; Yigit & Medvedev, ). In addition, GWs capable of propagating to the bottom side of the F region (∼150–300 km) may provide the seeds for the generation of equatorial spread F plasma bubbles (e.g., Huang & Kelley, ; Huang et al, ; Hysell et al, ; Sekar & Kelley, ; Sekar et al, ; Taylor et al, ).…”

Section: Introductionmentioning

confidence: 99%

Seasonal Propagation Characteristics of MSTIDs Observed at High Latitudes Over Central Alaska Using the Poker Flat Incoherent Scatter Radar

et al. 2018

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Near‐continuous electron density measurements obtained over a ∼3 year period, 2010–2013, using the Poker Flat Incoherent Scatter Radar (PFISR) in central Alaska (69°N, 147°W) have been analyzed to quantify the properties of over 650 high‐latitude medium‐scale traveling ionospheric disturbances (MSTIDs). Our analysis focused on the altitude range 100–300 km encompassing the lower ionosphere/thermosphere and yielded first full seasonal day/night distributions of MSTIDs at high northern latitudes with mean values: horizontal wavelength 446 km, horizontal phase speed 187 m/s, and period 41 min. These year‐round measurements fill an important summertime gap in existing MSTID measurements revealing predominantly eastward wave propagation during the summer, while continued winter season observations agree well with previous reports of near southward propagating MSTIDs. Our 3 years of results suggest a cyclic change in the seasonal horizontal propagation directions that was found to be quantitatively consistent with critical level wind and dissipative filtering. Concurrent measurements of the vertical wavelength spectrum as a function of altitude also compared favorably in shape with that calculated using a theoretical dispersion relation (Vadas & Fritts, 2005, https://doi.org/10.1029/2004JD005574) for the thermosphere, but with a higher mean value. Evidence supporting the systematic broadening and shrinking in the azimuthal distributions of the MSTIDs during the course of the year was also found, as well as an unexpected correlation between the MSTID propagation directions and the AE index, both of which are under further investigation.

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“…In addition, GWs can also induce planetary waves and tides in the T/I (e.g., Laštovička, 2006;Hoffmann et al, 2012, and references therein). Recently, Yigit and Medvedev (2017) showed that GWs can influence the migrating diurnal tide in the T/I. Although many advances have been achieved by recent studies focusing on vertical coupling by GWs between the middle atmosphere and the T/I, the mechanism of this coupling is not fully understood and open issues remain (e.g., see the review of Medvedev, 2015, 2016;.…”

Section: Q T Trinh Et Al: Satellite Observations Of Vertical Couplmentioning

confidence: 99%

Satellite observations of middle atmosphere–thermosphere vertical coupling by gravity waves

et al. 2018

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Abstract. Atmospheric gravity waves (GWs) are essential for the dynamics of the middle atmosphere. Recent studies have shown that these waves are also important for the thermosphere/ionosphere (T/I) system. Via vertical coupling, GWs can significantly influence the mean state of the T/I system. However, the penetration of GWs into the T/I system is not fully understood in modeling as well as observations. In the current study, we analyze the correlation between GW momentum fluxes observed in the middle atmosphere (30-90 km) and GW-induced perturbations in the T/I. In the middle atmosphere, GW momentum fluxes are derived from temperature observations of the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) satellite instrument. In the T/I, GW-induced perturbations are derived from neutral density measured by instruments on the Gravity field and Ocean Circulation Explorer (GOCE) and CHAllenging Minisatellite Payload (CHAMP) satellites. We find generally positive correlations between horizontal distributions at low altitudes (i.e., below 90 km) and horizontal distributions of GW-induced density fluctuations in the T/I (at 200 km and above). Two coupling mechanisms are likely responsible for these positive correlations: (1) fast GWs generated in the troposphere and lower stratosphere can propagate directly to the T/I and (2) primary GWs with their origins in the lower atmosphere dissipate while propagating upwards and generate secondary GWs, which then penetrate up to the T/I and maintain the spatial patterns of GW distributions in the lower atmosphere. The mountain-wave related hotspot over the Andes and Antarctic Peninsula is found clearly in observations of all instruments used in our analysis. Latitude-longitude variations in the summer midlatitudes are also found in observations of all instruments. These variations and strong positive correlations in the summer midlatitudes suggest that GWs with origins related to convection also propagate up to the T/I. Different processes which likely influence the vertical coupling are GW dissipation, possible generation of secondary GWs, and horizontal propagation of GWs. Limitations of the observations as well as of our research approach are discussed.

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Influence of parameterized small‐scale gravity waves on the migrating diurnal tide in Earth's thermosphere

Cited by 60 publications

References 93 publications

Temporal variability of tidal and gravity waves during a record long 10-day continuous lidar sounding

Temporal variability of tidal and gravity waves during a record long 10-day continuous lidar sounding

Seasonal Propagation Characteristics of MSTIDs Observed at High Latitudes Over Central Alaska Using the Poker Flat Incoherent Scatter Radar

Satellite observations of middle atmosphere–thermosphere vertical coupling by gravity waves

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