Low‐frequency oscillations of the gravity wave energy density in the lower atmosphere at low latitudes revealed by U.S. radiosonde data

Li, Hai Yan; Huang, Chun Ming; Zhang, Shaodong; Huang, Kai; Gong, Yun; Gan, Quan; Yue, Jia

doi:10.1002/2016jd025435

Cited by 11 publications

(10 citation statements)

References 60 publications

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“…Several studies investigated the relation between solar cycle and GW activity before, for example, Ern et al (2011), Li et al (2016 and Liu et al (2017): Ern et al (2011) indicated that there is an anti-correlation between the 10.7 cm solar flux and SABER GW amplitudes. Similarly, Liu et al (2017) found a negative response of SABER GW potential energy to solar activity at lower and middle latitudes.…”

Section: Gravity Wave Variations Potentially Related To the 11-year Solar Cyclementioning

confidence: 99%

Global analysis for periodic variations of gravity wave squared amplitudes and momentum fluxes in the middle atmosphere

Chen¹,

Strube²,

Ern³

et al. 2019

Preprint

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Abstract. Atmospheric gravity waves (GWs) are an important coupling mechanism in the middle atmosphere. For instance, they provide a large part of the driving of long-period atmospheric oscillations such as the quasi-biennial oscillation (QBO) and the semiannual oscillation (SAO) and are in turn modulated. They also induce the wind reversal in the mesosphere – lower thermosphere region (MLT) and the residual mean circulation at these altitudes. In this study, the variations of monthly zonal mean gravity wave square temperature amplitudes (GWSTA) and, for a first time, absolute gravity wave momentum flux (GWMF) on different time scales such as the annual, semiannual, terannual and quasi-biennial variations are investigated by spectrally analyzing SABER observations from 2002 to 2015. Latitude-altitude cross sections of spectral amplitudes and phases of GWSTA and absolute GWMF in stratosphere and mesosphere are presented and physically interpreted. It is shown that the time series of GWSTA/GWMF at a certain altitude and latitude results from the complex interplay of GW sources, propagation through and filtering in lower altitudes, oblique propagation superposing GWs from different source locations and, finally, the modulation of the GW spectrum by the winds at a considered altitude and latitude. The strongest component is the annual variation, dominated on the summer hemisphere by subtropical convective sources, and on the winter hemisphere by polar vortex dynamics. At heights of the wind reversal also a 180° phase shift occurs, which is at different altitudes for GWSTA and GWMF. In the intermediate latitudes a semi-annual variation (SAV) is found. Dedicated GW modeling is used to investigate the nature of this SAV, which is a different phenomenon from the tropical SAO also seen in the data. In the tropics a stratospheric and a mesospheric QBO are found, which are, as expected, in anti-phase. Indication for a QBO influence is also found at higher latitudes. In previous studies a terannual variation (TAV) was identified. In the current study we explain its origin. In particular the observed patterns for the shorter periods, SAV and TAV, can only be explained by poleward propagation of GWs from the lower stratosphere subtropics into the mid and high latitude mesosphere. In this way, critical wind filtering in the lowermost stratosphere is avoided and this oblique propagation hence is likely an important factor for MLT dynamics.

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Section: Gravity Wave Variations Potentially Related To the 11-year Solar Cyclementioning

confidence: 99%

Global analysis for periodic variations of gravity wave squared amplitudes and momentum fluxes in the middle atmosphere

Chen¹,

Strube²,

Ern³

et al. 2019

Preprint

View full text Add to dashboard Cite

show abstract

“…Gravity wave drag plays an important role in the whole middle atmosphere. It significantly contributes to the wind reversals at the top of the mesospheric wind jets (e.g., Lindzen, 1981;Holton, 1982Holton, , 1983. Further, gravity wave dissipation drives the meridional circulation in the mesosphere, which leads to the cold summer mesopause, the coldest region in Earth's atmosphere, as well as to the relatively warm winter stratopause.…”

Section: Introductionmentioning

confidence: 99%

“…Often, they assume a fixed source level and a homogeneous and isotropic launch distribution; i.e., they launch the same amount of momentum flux in different directions (for example, the four cardinal directions) at each model grid point. Some examples of such schemes are the schemes introduced by Lindzen (1981), Hines (1997), Alexander and Dunkerton (1999), Warner and McIntyre (2001), Scinocca (2003), or Yigit et al (2008. Different from this, orographic gravity wave parametrizations are dedicated to mountain waves that are excited by flow over topography, i.e., to a specific source process.…”

Section: Introductionmentioning

confidence: 99%

GRACILE: a comprehensive climatology of atmospheric gravity wave parameters based on satellite limb soundings

Ern

Trinh

Preusse

et al. 2018

Earth Syst. Sci. Data

135

162

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Abstract. Gravity waves are one of the main drivers of atmospheric dynamics. The spatial resolution of most global atmospheric models, however, is too coarse to properly resolve the small scales of gravity waves, which range from tens to a few thousand kilometers horizontally, and from below 1 km to tens of kilometers vertically. Gravity wave source processes involve even smaller scales. Therefore, general circulation models (GCMs) and chemistry climate models (CCMs) usually parametrize the effect of gravity waves on the global circulation. These parametrizations are very simplified. For this reason, comparisons with global observations of gravity waves are needed for an improvement of parametrizations and an alleviation of model biases. We present a gravity wave climatology based on atmospheric infrared limb emissions observed by satellite (GRACILE). GRACILE is a global data set of gravity wave distributions observed in the stratosphere and the mesosphere by the infrared limb sounding satellite instruments High Resolution Dynamics Limb Sounder (HIRDLS) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER). Typical distributions (zonal averages and global maps) of gravity wave vertical wavelengths and along-track horizontal wavenumbers are provided, as well as gravity wave temperature variances, potential energies and absolute momentum fluxes. This global data set captures the typical seasonal variations of these parameters, as well as their spatial variations. The GRACILE data set is suitable for scientific studies, and it can serve for comparison with other instruments (ground-based, airborne, or other satellite instruments) and for comparison with gravity wave distributions, both resolved and parametrized, in GCMs and CCMs. The GRACILE data set is available as supplementary data at https://doi.org/10.1594/PANGAEA.879658.

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“…Some of the most relevant are discussed in the following paragraph. For instance, GW activity exhibits a prominent annual cycle over midlatitudes in the stratosphere (Li et al, 2010;John and Kumar, 2012), and a semiannual signal is found in the mesosphere, which is caused by the seasonal change in mesospheric winds (Yang et al, 2010). From the upper troposphere to the lower stratosphere in the tropics, GWs exhibit variations related to the QBO (Vincent and Alexander, 2000;John and Kumar, 2012;Ern et al, 2014), while a semiannual oscillation is found in the tropical stratosphere (Zhang et al, 2012), stratopause region (Ern et al, 2015) and the mesosphere (Antonita et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Global analysis for periodic variations in gravity wave squared amplitudes and momentum fluxes in the middle atmosphere

Chen

Strube²,

Ern³

et al. 2019

Ann. Geophys.

View full text Add to dashboard Cite

Abstract. Atmospheric gravity waves (GWs) are an important coupling mechanism in the middle atmosphere. For instance, they provide a large part of the driving of long-period atmospheric oscillations such as the Quasi-Biennial Oscillation (QBO) and the semiannual oscillation (SAO) and are in turn modulated. They also induce the wind reversal in the mesosphere–lower thermosphere region (MLT) and the residual mean circulation at these altitudes. In this study, the variations in monthly zonal mean gravity wave square temperature amplitudes (GWSTAs) and, for the first time, absolute gravity wave momentum flux (GWMF) on different timescales such as the annual, semiannual, terannual and quasi-biennial variations are investigated by spectrally analyzing SABER observations from 2002 to 2015. Latitude–altitude cross sections of spectral amplitudes and phases of GWSTA and absolute GWMF in the stratosphere and mesosphere are presented and physically interpreted. It is shown that the time series of GWSTA and GWMF at a certain altitude and latitude results from the complex interplay of GW sources, propagation through and filtering in lower altitudes, oblique propagation superposing GWs from different source locations, and, finally, the modulation of the GW spectrum by the winds at a considered altitude and latitude. The strongest component is the annual variation, dominated in the summer hemisphere by subtropical convective sources and in the winter hemisphere by polar vortex dynamics. At heights of the wind reversal, a 180∘ phase shift also occurs, which is at different altitudes for GWSTA and GWMF. In the intermediate latitudes a semiannual variation (SAV) is found. Dedicated GW modeling is used to investigate the nature of this SAV, which is a different phenomenon from the tropical SAO also seen in the data. In the tropics a stratospheric and a mesospheric QBO are found, which are, as expected, in antiphase. Indication for a QBO influence is also found at higher latitudes. In previous studies a terannual variation (TAV) was identified. In the current study we explain its origin. In particular the observed patterns for the shorter periods, SAV and TAV, can only be explained by poleward propagation of GWs from the lower-stratosphere subtropics into the midlatitude and high-latitude mesosphere. In this way, critical wind filtering in the lowermost stratosphere is avoided and this oblique propagation is hence likely an important factor for MLT dynamics.

show abstract

Low‐frequency oscillations of the gravity wave energy density in the lower atmosphere at low latitudes revealed by U.S. radiosonde data

Cited by 11 publications

References 60 publications

Global analysis for periodic variations of gravity wave squared amplitudes and momentum fluxes in the middle atmosphere

Global analysis for periodic variations of gravity wave squared amplitudes and momentum fluxes in the middle atmosphere

GRACILE: a comprehensive climatology of atmospheric gravity wave parameters based on satellite limb soundings

Global analysis for periodic variations in gravity wave squared amplitudes and momentum fluxes in the middle atmosphere

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