Analysis of internal gravity waves with GPS RO density profiles

Šácha, Petr; Foelsche, Ulrich; Pišoft, Petr

doi:10.5194/amt-7-4123-2014

Cited by 13 publications

(8 citation statements)

References 35 publications

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“…Finally, in connection with the jet location above the region of interest, we can expect a strong contribution to the IGW spectrum from spontaneous emission processes (Plougonven and Zhang, 2014). Evidence for this claim can be found, e.g., in Hirota and Niki (1985) and Sato (1994), who analysed middle and upper atmospheric radar data (located at Shigaraki, Japan, falling into our region of interest) and who found inertia IGWs propagating upward and downward from the jet stream. Orographic waves were also identified.…”

Section: Possible Wave Sourcesmentioning

confidence: 62%

Enhanced internal gravity wave activity and breaking over the northeastern Pacific–eastern Asian region

Šácha

Kuchař²,

Jacobi

et al. 2015

Atmos. Chem. Phys.

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Abstract. We have found a stratospheric area of anomalously low annual cycle amplitude and specific dynamics in the stratosphere over the northeastern Pacific–eastern Asia coastal region. Using GPS radio occultation density profiles from the Formosat Satellite Mission 3/Constellation Observing System for Meteorology, Ionosphere, and Climate (FORMOSAT-3/COSMIC), we have discovered an internal gravity wave (IGW) activity and breaking hotspot in this region. Conditions supporting orographic wave sourcing and propagation were found. Other possible sources of wave activity in this region are listed. The reasons why this particular IGW activity hotspot was not discovered before as well as why the specific dynamics of this region have not been pointed out are discussed together with the weaknesses of using the mean potential energy as a wave activity proxy. Possible consequences of the specific dynamics in this region on the middle atmospheric dynamics and transport are outlined.

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Section: Possible Wave Sourcesmentioning

confidence: 62%

Enhanced internal gravity wave activity and breaking over the northeastern Pacific–eastern Asian region

Šácha

Kuchař²,

Jacobi

et al. 2015

Atmos. Chem. Phys.

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“…Since the early approaches of Fetzer and Gille (1994), Wu and Waters (1996), and Eckermann and Preusse (1999), many studies have been initiated to collect gravity wave information from space using techniques like limb sounding (Preusse et al, 2002;M. J. Alexander et al, 2008;Wright and Gille, 2011;Ern et al, 2018), microwave sub-limb sounding (McLandress et al, 2000;Jiang et al, 2004b, a;Wu and Eckermann, 2008), infrared (IR) and microwave nadir sounding (Wu, 2004;Eckermann et al, 2006Eckermann et al, , 2007Hoffmann and Alexander, 2009;Gong et al, 2012;Hoffmann et al, 2016;Wright et al, 2017;Ern et al, 2017), and GPS-RO (Tsuda et al, 2000;Fröhlich et al, 2007;Schmidt et al, 2008;Wang and Alexander, 2010;Šácha et al, 2014, 2015Rapp et al, 2018a). All these measurements rely on scale separation to discern gravity wave signals from a background atmosphere.…”

Section: Introductionmentioning

confidence: 99%

Removing spurious inertial instability signals from gravity wave temperature perturbations using spectral filtering methods

et al. 2020

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Abstract. Gravity waves are important drivers of dynamic processes in particular in the middle atmosphere. To analyse atmospheric data for gravity wave signals, it is essential to separate gravity wave perturbations from atmospheric variability due to other dynamic processes. Common methods to separate small-scale gravity wave signals from a large-scale background are separation methods depending on filters in either the horizontal or vertical wavelength domain. However, gravity waves are not the only process that could lead to small-scale perturbations in the atmosphere. Recently, concerns have been raised that vertical wavelength filtering can lead to misinterpretation of other wave-like perturbations, such as inertial instability effects, as gravity wave perturbations. In this paper we assess the ability of different spectral background removal approaches to separate gravity waves and inertial instabilities using artificial inertial instability perturbations, global model data and satellite observations. We investigate a horizontal background removal (which applies a zonal wavenumber filter with additional smoothing of the spectral components in meridional and vertical direction), a sophisticated filter based on 2D time–longitude spectral analysis (see Ern et al., 2011) and a vertical wavelength Butterworth filter. Critical thresholds for the vertical wavelength and zonal wavenumber are analysed. Vertical filtering has to cut deep into the gravity wave spectrum in order to remove inertial instability remnants from the perturbations (down to 6 km cutoff wavelength). Horizontal filtering, however, removes inertial instability remnants in global model data at wavenumbers far lower than the typical gravity wave scales for the case we investigated. Specifically, a cutoff zonal wavenumber of 6 in the stratosphere is sufficient to eliminate inertial instability structures. Furthermore, we show that for infrared limb-sounding satellite profiles it is possible as well to effectively separate perturbations of inertial instabilities from those of gravity waves using a cutoff zonal wavenumber of 6. We generalize the findings of our case study by examining a 1-year time series of SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) data.

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“…Экспериментальное определение и анализ географических и сезонных распределений характеристик внутренних волн [Губенко и др., 2012, 2015, 2016b] являются необходимыми и важными этапами при построении адекватных моделей общей циркуляции атмосферы Земли. Разработанный нами оригинальный метод идентификации волновых событий и реконструкции характеристик ВГВ в атмосферах планет [Gubenko et al, 2008b[Gubenko et al, , 2011Губенко и др., 2012, 2016a получил широкое признание научного сообщества как в России, так и за рубежом и в настоящее время успешно применяется при исследовании волновых процессов в атмосфере Земли Xiao, Hu, 2010;Sacha et al, 2014;Zagar et al, 2017] и Венеры Peralta et al, 2015]. В частности, исследователи из Франции и Швеции в своей работе показали, что данные численного моделирования и анализ независимых радарных и зондовых измерений в атмосфере Земли демонстрируют высокую эффективность разработанного нами метода и хорошую надежность получаемых на его основе научных результатов.…”

Section: Introductionunclassified

Diagnostics of internal atmospheric wave saturation and determination of their characteristics in Earth’s stratosphere from radiosonde measurements

Губенко¹,

Kirillovich²

2018

Solnechno-Zemnaya Fizika

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Internal gravity waves (IGW) significantly affect the structure and circulation of Earth’s atmosphere by transporting wave energy and momentum upward from the lower atmosphere. Since IGW can propagate freely through a stably stratified atmosphere, similar effects may occur in the atmospheres of Mars and Venus. Observations of temperature and wind speed fluctuations induced by internal waves in Earth’s atmosphere have shown that wave amplitudes increase with height, but not quickly enough to correspond to the amplitude increase due to an exponential decrease in the density without energy dissipation. The linear theory of IGW explains the wave amplitude growth rate as follows: any wave amplitude exceeding the threshold value leads to instability and produces turbulence, which hinders further amplitude growth (internal wave saturation). The mechanisms that contribute most to the energy dissipation and saturation of IGW in the atmosphere are thought to be the dynamical (shear) and convective instabilities. The assumption of internal wave saturation plays a key role in radio occultation (RO) monitoring of IGW in planetary atmospheres. A radiosonde study of wave saturation processes in Earth’s atmosphere is therefore actual and important task. We report the results of determination of actual and threshold amplitudes, saturation degree, and other characteristics for the identified IGW in Earth’s atmosphere obtained from the analysis of SPARC (Stratospheric Processes And their Role in Climate) radiosonde measurements of wind speed and temperature [http://www.sparc.sunysb.edu/].

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Analysis of internal gravity waves with GPS RO density profiles

Cited by 13 publications

References 35 publications

Enhanced internal gravity wave activity and breaking over the northeastern Pacific–eastern Asian region

Enhanced internal gravity wave activity and breaking over the northeastern Pacific–eastern Asian region

Removing spurious inertial instability signals from gravity wave temperature perturbations using spectral filtering methods

Diagnostics of internal atmospheric wave saturation and determination of their characteristics in Earth’s stratosphere from radiosonde measurements

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