scholarly journals Ozone-Gravity Wave Interaction in the Upper Stratosphere/Lower Mesosphere

2022 ◽  
Author(s):  
Axel Gabriel
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
General Circulation ◽  
Low Frequency ◽  
Wave Interaction ◽  
General Circulation Models ◽  
Intrinsic Frequency ◽  
Night Time ◽  
Ozone Photochemistry ◽  
Middle Stratosphere

Abstract. The increase in amplitudes of upward propagating gravity waves (GWs) with height due to decreasing density is usually described by exponential growth; however, recent measurements detected a much stronger increase in gravity wave potential energy density (GWPED) during daylight than night-time (increase by a factor of about 4 to 8 between middle stratosphere and upper mesosphere), which is not well understood up to now. This paper suggests that ozone-gravity wave interaction in the upper stratosphere/lower mesosphere is largely responsible for this phenomenon. The coupling between ozone-photochemistry and temperature is particularly strong in the upper stratosphere where the time-mean ozone mixing ratio is decreasing with height; therefore, an initial uplift of an air parcel must lead to a local increase in ozone and in the heating rate compared to the environment, and, hence, to an amplification of the initial uplift. Standard solutions of upward propagating GWs with linear ozone-temperature coupling are formulated suggesting local amplitude amplifications during daylight of 5 to 15 % for low-frequency GWs (periods ≥4 hours), as a function of the intrinsic frequency which decreases if ozone-temperature coupling is included. Subsequently, for horizontal wavelengths larger than 500 km and vertical wavelengths smaller than 5 km, the cumulative amplification during the upward level-by-level propagation leads to much stronger amplitudes in the GW perturbations (factor of about 1.5 to 3) and in the GWPED (factor of about 3 to 9) at upper mesospheric altitudes. The results open a new viewpoint for improving general circulation models with resolved or parameterized GWs.

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

2017 ◽  
Author(s):  
Kathrin Baumgarten ◽  
Michael Gerding ◽  
Gerd Baumgarten ◽  
Franz-Josef Lübken
Keyword(s):  
Gravity Waves ◽  
General Circulation ◽  
Middle Atmosphere ◽  
Wave Interaction ◽  
Weather Conditions ◽  
General Circulation Models ◽  
Driving Mechanism ◽  
Lidar Measurement ◽  
Large Variability ◽  
Tidal Waves

Abstract. Gravity waves (GW) 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 infected by tidal waves as they modulate the mean background wind field and vice versa, which is not yet fully understood and not implemented in many circulation models. The daylight capable Rayleigh-Mie-Raman (RMR) lidar at Kühlungsborn (54° N, 12&deg 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 time scales of days. Using a 1-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 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 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 GW in general circulation models.

scholarly journals Propagation Paths and Source Distributions of Resolved Gravity Waves in ECMWF-IFS analysis fields around the Southern Polar Night Jet

2021 ◽  
Author(s):  
Cornelia Strube ◽  
Peter Preusse ◽  
Manfred Ern ◽  
Martin Riese
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
General Circulation ◽  
Lateral Displacement ◽  
General Circulation Models ◽  
Wave Drag ◽  
Wave Activity ◽  
Lateral Shift ◽  
Wave Ray ◽  
Propagation Paths

Abstract. In the southern winter polar stratosphere the distribution of gravity wave momentum flux in many state-of-the-art climate simulations is inconsistent with long-time satellite and superpressure balloon observations around 60° S. Recent studies hint that a lateral shift between prominent gravity wave sources in the tropospheric mid-latitudes and the location where gravity wave activity is present in the stratosphere causes at least parts of the discrepancy. This lateral shift cannot be represented by the column-based gravity wave drag parametrisations used in most general circulation models. However, recent high-resolution analysis and re-analysis products of the ECMWF-IFS show good agreement to observations and allow for a detailed investigation of resolved gravity waves, their sources and propagation paths. In this paper, we identify resolved gravity waves in the ECMWF-IFS analyses for a case of high gravity wave activity in the lower stratosphere using small-volume sinusoidal fits to characterise these gravity waves. The 3D wave vector together with perturbation amplitudes, wave frequency and a fully described background atmosphere are then used to initialise the GROGRAT gravity wave ray-tracer and follow the gravity waves backwards from the stratosphere. Finally, we check for indication of source processes on the path of each ray and thus quantitatively attribute gravity waves to sources that are represented within the model. We find that stratospheric gravity waves are indeed subject to far (> 1000 km) lateral displacement from their sources, taking place already at low altitudes (

scholarly journals First tomographic observations of gravity waves by the infrared limb imager GLORIA

2017 ◽  
Vol 17 (24) ◽  
pp. 14937-14953 ◽  
Author(s):  
Isabell Krisch ◽  
Peter Preusse ◽  
Jörn Ungermann ◽  
Andreas Dörnbrack ◽  
Stephen D. Eckermann ◽  
...  
Keyword(s):  
Ray Tracing ◽  
Gravity Wave ◽  
Gravity Waves ◽  
General Circulation ◽  
Wave Packets ◽  
Source Region ◽  
General Circulation Models ◽  
Climate Projections ◽  
Flight Pattern ◽  
The Waves

Abstract. Atmospheric gravity waves are a major cause of uncertainty in atmosphere general circulation models. This uncertainty affects regional climate projections and seasonal weather predictions. Improving the representation of gravity waves in general circulation models is therefore of primary interest. In this regard, measurements providing an accurate 3-D characterization of gravity waves are needed. Using the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA), the first airborne implementation of a novel infrared limb imaging technique, a gravity wave event over Iceland was observed. An air volume disturbed by this gravity wave was investigated from different angles by encircling the volume with a closed flight pattern. Using a tomographic retrieval approach, the measurements of this air mass at different angles allowed for a 3-D reconstruction of the temperature and trace gas structure. The temperature measurements were used to derive gravity wave amplitudes, 3-D wave vectors, and direction-resolved momentum fluxes. These parameters facilitated the backtracing of the waves to their sources on the southern coast of Iceland. Two wave packets are distinguished, one stemming from the main mountain ridge in the south of Iceland and the other from the smaller mountains in the north. The total area-integrated fluxes of these two wave packets are determined. Forward ray tracing reveals that the waves propagate laterally more than 2000 km away from their source region. A comparison of a 3-D ray-tracing version to solely column-based propagation showed that lateral propagation can help the waves to avoid critical layers and propagate to higher altitudes. Thus, the implementation of oblique gravity wave propagation into general circulation models may improve their predictive skills.

scholarly journals Constraints on Wave Drag Parameterization Schemes for Simulating the Quasi-Biennial Oscillation. Part II: Combined Effects of Gravity Waves and Equatorial Planetary Waves

2005 ◽  
Vol 62 (12) ◽  
pp. 4196-4205 ◽  
Author(s):  
Lucy J. Campbell ◽  
Theodore G. Shepherd
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
General Circulation ◽  
Planetary Wave ◽  
General Circulation Models ◽  
Wave Drag ◽  
Planetary Waves ◽  
Small Contribution ◽  
Quasi Biennial Oscillation ◽  
Biennial Oscillation

Abstract This study examines the effect of combining equatorial planetary wave drag and gravity wave drag in a one-dimensional zonal mean model of the quasi-biennial oscillation (QBO). Several different combinations of planetary wave and gravity wave drag schemes are considered in the investigations, with the aim being to assess which aspects of the different schemes affect the nature of the modeled QBO. Results show that it is possible to generate a realistic-looking QBO with various combinations of drag from the two types of waves, but there are some constraints on the wave input spectra and amplitudes. For example, if the phase speeds of the gravity waves in the input spectrum are large relative to those of the equatorial planetary waves, critical level absorption of the equatorial planetary waves may occur. The resulting mean-wind oscillation, in that case, is driven almost exclusively by the gravity wave drag, with only a small contribution from the planetary waves at low levels. With an appropriate choice of wave input parameters, it is possible to obtain a QBO with a realistic period and to which both types of waves contribute. This is the regime in which the terrestrial QBO appears to reside. There may also be constraints on the initial strength of the wind shear, and these are similar to the constraints that apply when gravity wave drag is used without any planetary wave drag. In recent years, it has been observed that, in order to simulate the QBO accurately, general circulation models require parameterized gravity wave drag, in addition to the drag from resolved planetary-scale waves, and that even if the planetary wave amplitudes are incorrect, the gravity wave drag can be adjusted to compensate. This study provides a basis for knowing that such a compensation is possible.

scholarly journals Gravity wave variances and propagation derived from AIRS radiances

2011 ◽  
Vol 11 (4) ◽  
pp. 11691-11738 ◽  
Author(s):  
J. Gong ◽  
D. L. Wu ◽  
S. D. Eckermann
Keyword(s):  
Gravity Wave ◽  
General Circulation ◽  
Deep Convection ◽  
Low Frequency ◽  
General Circulation Models ◽  
Satellite Orbits ◽  
Atmospheric Infrared Sounder ◽  
Quasi Biennial Oscillation ◽  
Mountain Ranges ◽  
Cross Track

Abstract. As the first gravity wave (GW) climatology study using nadir-viewing infrared sounders, 50 Atmospheric Infrared Sounder (AIRS) radiance channels are selected to estimate GW variances at pressure levels between 2–100 hPa. The GW variance for each scan in the cross-track direction is derived from radiance perturbations in the scan, independently of adjacent scans along the orbit. Since the scanning swaths are perpendicular to the satellite orbits, which are inclined meridionally at most latitudes, the zonal component of GW propagation can be inferred by differencing the variances derived between the westmost and the eastmost viewing angles. Consistent with previous GW studies using various satellite instruments, monthly mean AIRS variance shows large enhancements over meridionally oriented mountain ranges as well as some islands at winter hemisphere high latitudes. Enhanced wave activities are also found above tropical deep convective regions. GWs prefer to propagate westward above mountain ranges, and eastward above deep convection. AIRS 90 field-of-views (FOVs), ranging from +48° to −48° off nadir, can detect large-amplitude GWs with a phase velocity propagating preferentially at steep angles (e.g., those from orographic and convective sources). The annual cycle dominates the GW variances and the preferred propagation directions for all latitudes. Quasi-biennial oscillation (QBO) signals are also found in the tropical lower stratosphere despite their small amplitudes. From 90 AIRS FOV radiance measurements, we are able to clearly identify measurement noises, high-frequency internal GWs, and low-frequency inertia GWs. Even though the vertical wavelengths of inertia GWs are shorter than the thickness of instrument weighting functions, simulations support the AIRS sensitivity to these waves. The novel discovery of AIRS capability of observing shallow inertia GWs will expand the potential of satellite GW remote sensing and provide further constraints on the GW drag parameterization schemes in the general circulation models (GCMs).

scholarly journals GRACILE: A comprehensive climatology of atmospheric gravity wave parameters based on satellite limb soundings

2018 ◽  
Author(s):  
Manfred Ern ◽  
Quang Thai Trinh ◽  
Peter Preusse ◽  
John C. Gille ◽  
Martin G. Mlynczak ◽  
...  
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
General Circulation ◽  
Climate Models ◽  
General Circulation Models ◽  
Atmospheric Gravity Wave ◽  
Data Set ◽  
Wave Source ◽  
Global Data ◽  
Satellite Instruments

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.

scholarly journals Lagrangian Gravity Wave spectra in the lower stratosphere of current (re)analyses

2020 ◽  
Author(s):  
Aurélien Podglajen ◽  
Albert Hertzog ◽  
Riwal Plougonven ◽  
Bernard Legras
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Lower Stratosphere ◽  
Weather Prediction ◽  
Low Frequency ◽  
Vertical Wind ◽  
Temperature Fields ◽  
Intrinsic Frequency ◽  
Telecommunication System ◽  
Global Telecommunication System

Abstract. Due to their increasing spatial resolution, numerical weather prediction (NWP) models and the associated analyses resolve a growing fraction of the gravity wave (GW) spectrum. However, it is unclear how well this resolved part of the spectrum actually compares to the actual atmospheric variability. In particular, the Lagrangian variability, relevant, e.g., to atmospheric dispersion and to microphysical modeling in the Upper Troposphere-Lower Stratosphere (UTLS), has not yet been documented in recent products. To address this shortcoming, this paper presents an assessment of the GW spectrum as a function of the intrinsic (air parcel following) frequency in recent (re)analyses (ERA-interim, ERA5, the ECMWF operational analysis, MERRA-2 and JRA-55). Long-duration, quasi-Lagrangian balloon observations in the equatorial and Antarctic lower stratosphere are used as a reference for the atmospheric spectrum and compared to synthetic balloon observations along trajectories calculated using the wind and temperature fields of the reanalyses. Overall, the reanalyses represent realistic features of the spectrum, notably the spectral gap between planetary and gravity waves and a peak in horizontal kinetic energy associated with inertial waves near f in the polar region. In the tropics, they represent the slope of the spectrum at low frequency. However, the variability is generally underestimated, even in the low-frequency portion of the spectrum. In particular, the near-inertial peak, although present in the reanalyses, has a much reduced magnitude compared to balloon observations. We compare the variability of temperature, momentum flux and vertical wind speed, which are related to low, mid and high frequency waves, respectively. The distributions (PDFs) have similar shapes, but show increasing disagreement with increasing intrinsic frequency. Since at those altitudes they are mainly caused by gravity waves, we also compare the geographic distribution of vertical wind fluctuations in the different products, which emphasizes the increase of both GW variance and intermittency with horizontal resolution. Finally, we quantify the fraction of resolved variability and its dependency on model resolution for the different variables. In all (re)analyses products, a significant part of the variability is still missing and should hence be parameterized, in particular at high intrinsic frequency. Among the two polar balloon datasets used, one was broadcast on the global telecommunication system for assimilation in analyses while the other is made of independent observations (unassimilated in the reanalyses). Comparing the Lagrangian spectra between the two campaigns shows that they are largely influenced by balloon data assimilation, which especially enhances the variance at low frequency.

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

2018 ◽  
Vol 10 (2) ◽  
pp. 857-892 ◽  
Author(s):  
Manfred Ern ◽  
Quang Thai Trinh ◽  
Peter Preusse ◽  
John C. Gille ◽  
Martin G. Mlynczak ◽  
...  
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
General Circulation ◽  
Climate Models ◽  
General Circulation Models ◽  
Atmospheric Gravity Wave ◽  
Data Set ◽  
Wave Source ◽  
Global Data ◽  
Satellite Instruments

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.

scholarly journals Gravity waves in the winter stratosphere over the Southern Ocean: high-resolution satellite observations and 3-D spectral analysis

2019 ◽  
Vol 19 (24) ◽  
pp. 15377-15414 ◽  
Author(s):  
Neil P. Hindley ◽  
Corwin J. Wright ◽  
Nathan D. Smith ◽  
Lars Hoffmann ◽  
Laura A. Holt ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Gravity Wave ◽  
Gravity Waves ◽  
General Circulation ◽  
Large Scale ◽  
General Circulation Models ◽  
Southern Andes ◽  
The North ◽  
Short Timescale ◽  
Momentum Fluxes

Abstract. Atmospheric gravity waves play a key role in the transfer of energy and momentum between layers of the Earth's atmosphere. However, nearly all general circulation models (GCMs) seriously under-represent the momentum fluxes of gravity waves at latitudes near 60∘ S, which can lead to significant biases. A prominent example of this is the “cold pole problem”, where modelled winter stratospheres are unrealistically cold. There is thus a need for large-scale measurements of gravity wave fluxes near 60∘ S, and indeed globally, to test and constrain GCMs. Such measurements are notoriously difficult, because they require 3-D observations of wave properties if the fluxes are to be estimated without using significant limiting assumptions. Here we use 3-D satellite measurements of stratospheric gravity waves from NASA's Atmospheric Infrared Sounder (AIRS) Aqua instrument. We present the first extended application of a 3-D Stockwell transform (3DST) method to determine localised gravity wave amplitudes, wavelengths and directions of propagation around the entire region of the Southern Ocean near 60∘ S during austral winter 2010. We first validate our method using a synthetic wavefield and two case studies of real gravity waves over the southern Andes and the island of South Georgia. A new technique to overcome wave amplitude attenuation problems in previous methods is also presented. We then characterise large-scale gravity wave occurrence frequencies, directional momentum fluxes and short-timescale intermittency over the entire Southern Ocean. Our results show that highest wave occurrence frequencies, amplitudes and momentum fluxes are observed in the stratosphere over the mountains of the southern Andes and Antarctic Peninsula. However, we find that around 60 %–80 % of total zonal-mean momentum flux is located over the open Southern Ocean during June–August, where a large “belt” of increased wave occurrence frequencies, amplitudes and fluxes is observed. Our results also suggest significant short-timescale variability of fluxes from both orographic and non-orographic sources in the region. A particularly striking result is a widespread convergence of gravity wave momentum fluxes towards latitudes around 60∘ S from the north and south. We propose that this convergence, which is observed at nearly all longitudes during winter, could account for a significant part of the under-represented flux in GCMs at these latitudes.

scholarly journals A two-dimensional Stockwell Transform for gravity wave analysis of AIRS measurements

2016 ◽  
Author(s):  
N. P. Hindley ◽  
N. D. Smith ◽  
C. J. Wright ◽  
N. J. Mitchell
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Momentum Flux ◽  
General Circulation ◽  
Middle Atmosphere ◽  
Critical Role ◽  
General Circulation Models ◽  
Two Dimensional ◽  
Wave Analysis ◽  
Stockwell Transform

Abstract. Gravity waves play a critical role in the dynamics of the middle atmosphere due to their ability to transport energy and momentum from their sources to great heights. The accurate parametrization of gravity wave momentum flux is of key importance to general circulation models. For the last decade, the nadir-viewing Atmospheric Infrared Sounder (AIRS) aboard NASA’s Aqua satellite has made global, two-dimensional (2-D) measurements of stratospheric radiances in which gravity waves can be detected. Current methods for gravity wave analysis of these data can introduce unwanted biases. Here, we present a new analysis method. Our method uses a 2-D Stockwell transform (2DST) to determine gravity wave horizontal wavelengths and directions in both directions simultaneously. We demonstrate that our method can accurately recover horizontal wavelengths and directions from a specified wave field. We show that the use of an elliptical spectral windowing function in the 2DST, in place of a Gaussian, can dramatically improve the recovery of wave amplitude. We measure momentum flux in two granules of AIRS measurements in two regions known to be intense hot spots of gravity wave activity: (i) the Drake Pas- sage/Antarctic Peninsula and (ii) the isolated mountainous island of South Georgia. We show that our 2DST method provides improved spatial localisation of key gravity wave properties over current methods. The added flexibility offered by alternative spectral windowing functions and scaling parameters presented here extend the usefulness of our 2DST method to other areas of geophysical data analysis.

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