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

2017 ◽  
Author(s):  
Isabell Krisch ◽  
Peter Preusse ◽  
Jörn Ungermann ◽  
Andreas Dörnbrack ◽  
Stephen D. Eckermann ◽  
...  
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Wave Packets ◽  
Regional Climate ◽  
Climate Projections ◽  
Atmospheric Models ◽  
The South ◽  
Flight Pattern ◽  
The North ◽  
The Waves

Abstract. Atmospheric gravity waves are a major cause of uncertainty in global atmospheric models. This uncertainty affects regional climate projections and seasonal weather predictions. Improving the representation of gravity waves in global atmospheric 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 measured. 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 under 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 south coast of Iceland. Two wave packets are distinguished, one stemming from the main mountain ridge in the South of Iceland, a second one from the smaller mountains in the North. The total, area-integrated fluxes of these two wave packets are determined. Following the waves forward with a ray-tracing model highlighted the importance of 3-D propagation, an effect generally neglected in global atmospheric models.

scholarly journals Mesospheric gravity waves observed near equatorial and low–middle latitude stations: wave characteristics and reverse ray tracing results

2006 ◽  
Vol 24 (12) ◽  
pp. 3229-3240 ◽  
Author(s):  
C. M. Wrasse ◽  
T. Nakamura ◽  
H. Takahashi ◽  
A. F. Medeiros ◽  
M. J. Taylor ◽  
...  
Keyword(s):  
Ray Tracing ◽  
Gravity Wave ◽  
Gravity Waves ◽  
Source Region ◽  
Phase Speed ◽  
Middle Latitude ◽  
Wave Source ◽  
Middle Latitudes ◽  
Summer Time ◽  
The Waves

Abstract. Gravity wave signatures were extracted from OH airglow observations using all-sky CCD imagers at four different stations: Cachoeira Paulista (CP) (22.7° S, 45° W) and São João do Cariri (7.4° S, 36.5° W), Brazil; Tanjungsari (TJS) (6.9° S, 107.9° E), Indonesia and Shigaraki (34.9° N, 136° E), Japan. The gravity wave parameters are used as an input in a reverse ray tracing model to study the gravity wave vertical propagation trajectory and to estimate the wave source region. Gravity waves observed near the equator showed a shorter period and a larger phase velocity than those waves observed at low-middle latitudes. The waves ray traced down into the troposphere showed the largest horizontal wavelength and phase speed. The ray tracing results also showed that at CP, Cariri and Shigaraki the majority of the ray paths stopped in the mesosphere due to the condition of m2<0, while at TJS most of the waves are traced back into the troposphere. In summer time, most of the back traced waves have their final position stopped in the mesosphere due to m2<0 or critical level interactions (|m|→∞), which suggests the presence of ducting waves and/or waves generated in-situ. In the troposphere, the possible gravity wave sources are related to meteorological front activities and cloud convections at CP, while at Cariri and TJS tropical cloud convections near the equator are the most probable gravity wave sources. The tropospheric jet stream and the orography are thought to be the major responsible sources for the waves observed at Shigaraki.

scholarly journals Superposition of gravity waves with different propagation characteristics observed by airborne and space-borne infrared sounders

2020 ◽  
Author(s):  
Isabell Krisch ◽  
Manfred Ern ◽  
Lars Hoffmann ◽  
Peter Preusse ◽  
Cornelia Strube ◽  
...  
Keyword(s):  
Ray Tracing ◽  
Gravity Wave ◽  
Gravity Waves ◽  
Decomposition Method ◽  
Wave Packets ◽  
Wave Structure ◽  
Multiple Wave ◽  
Wave Decomposition ◽  
D Wave ◽  
Middle Stratosphere

Abstract. A complex gravity wave structure consisting of a superposition of multiple wave packets was observed above southern Scandinavia on 28 January 2016 with the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA). The tomographic measurement capability of GLORIA enabled a detailed 3-D reconstruction of the gravity wave field and the identification of multiple wave packets with different horizontal and vertical scales. The larger-scale gravity waves with horizontal wavelengths 5 around 400 km could be characterised using a 3-D wave-decomposition method. For the characterization of the smaller-scale wave components with horizontal wavelengths below 200 km, the 3-D wave-decomposition method needs to be further improved in the future. For the larger-scale gravity wave components, a combination of gravity-wave ray-tracing calculations and ERA5 reanalysis fields identified orography as well as a jet-exit region and a low pressure system as possible sources. All gravity waves propagate 10 upward into the middle stratosphere, but only the orographic waves stay directly above their source. The comparison with ERA5 also shows that ray-tracing provides reasonable results even for such complex cases with multiple overlapping wave packets. AIRS measurements in the middle stratosphere support these findings, even though their coarse vertical resolution barely resolves the observed wave structure in this case study. The high-resolution GLORIA observations are therefore an important source of information on gravity wave characteristics in the upper troposphere and lower stratosphere region.

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 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 Superposition of gravity waves with different propagation characteristics observed by airborne and space-borne infrared sounders

2020 ◽  
Vol 20 (19) ◽  
pp. 11469-11490
Author(s):  
Isabell Krisch ◽  
Manfred Ern ◽  
Lars Hoffmann ◽  
Peter Preusse ◽  
Cornelia Strube ◽  
...  
Keyword(s):  
Ray Tracing ◽  
Gravity Wave ◽  
Gravity Waves ◽  
Wave Packets ◽  
Pressure System ◽  
Multiple Wave ◽  
Measurement Capability ◽  
Wave Ray ◽  
Complex Cases ◽  
Middle Stratosphere

Abstract. Many gravity wave analyses, based on either observations or model simulations, assume the presence of only a single dominant wave. This paper shows that there are much more complex cases with gravity waves from multiple sources crossing each others' paths. A complex gravity wave structure consisting of a superposition of multiple wave packets was observed above southern Scandinavia on 28 January 2016 with the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA). The tomographic measurement capability of GLORIA enabled a detailed 3-D reconstruction of the gravity wave field and the identification of multiple wave packets with different horizontal and vertical scales. The larger-scale gravity waves with horizontal wavelengths of around 400 km could be characterised using a 3-D wave-decomposition method. The smaller-scale wave components with horizontal wavelengths below 200 km were discussed by visual inspection. For the larger-scale gravity wave components, a combination of gravity-wave ray-tracing calculations and ERA5 reanalysis fields identified orography as well as a jet-exit region and a low-pressure system as possible sources. All gravity waves are found to propagate upward into the middle stratosphere, but only the orographic waves stay directly above their source. The comparison with ERA5 also shows that ray tracing provides reasonable results even for such complex cases with multiple overlapping wave packets. Despite their coarser vertical resolution compared to GLORIA measurements, co-located AIRS measurements in the middle stratosphere are in good agreement with the ray tracing and ERA5 results, proving once more the validity of simple ray-tracing models. Thus, this paper demonstrates that the high-resolution GLORIA observations in combination with simple ray-tracing calculations can provide an important source of information for enhancing our understanding of gravity wave propagation.

scholarly journals Characteristics and sources of gravity waves observed in noctilucent cloud over Norway

2014 ◽  
Vol 14 (22) ◽  
pp. 12133-12142 ◽  
Author(s):  
T. D. Demissie ◽  
P. J. Espy ◽  
N. H. Kleinknecht ◽  
M. Hatlen ◽  
N. Kaifler ◽  
...  
Keyword(s):  
Ray Tracing ◽  
Gravity Waves ◽  
Source Region ◽  
Digital Camera ◽  
Coastal Region ◽  
Primary Source ◽  
Noctilucent Cloud ◽  
The North ◽  
The Waves

Abstract. Four years of noctilucent cloud (NLC) images from an automated digital camera in Trondheim and results from a ray-tracing model are used to extend the climatology of gravity waves to higher latitudes and to identify their sources during summertime. The climatology of the summertime gravity waves detected in NLC between 64 and 74° N is similar to that observed between 60 and 64° N by Pautet et al. (2011). The direction of propagation of gravity waves observed in the NLC north of 64° N is a continuation of the north and northeast propagation as observed in south of 64° N. However, a unique population of fast, short wavelength waves propagating towards the SW is observed in the NLC, which is consistent with transverse instabilities generated in situ by breaking gravity waves (Fritts and Alexander, 2003). The relative amplitude of the waves observed in the NLC Mie scatter have been combined with ray-tracing results to show that waves propagating from near the tropopause, rather than those resulting from secondary generation in the stratosphere or mesosphere, are more likely to be the sources of the prominent wave structures observed in the NLC. The coastal region of Norway along the latitude of 70° N is identified as the primary source region of the waves generated near the tropopause.

Inertia-Gravity Wave Generation Near Upper Jets in the Australian Region

2020 ◽  
Author(s):  
Michael Reeder ◽  
Adam Morgan
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Source Region ◽  
Nonlinear Flow ◽  
Australian Region ◽  
Flow Imbalance ◽  
Unique Shape ◽  
The Waves ◽  
Active Convection ◽  
Q Vector

&lt;p&gt;During rapid extratropical cyclogenesis in the Australian region, distinctive striated, triangular-shaped clouds commonly form on the poleward side of the jet exit near the axis of inflection between an upstream trough and downstream ridge. These clouds are called striated deltas and the striations are shown here to be caused by radiating inertia-gravity waves. An analysis of 28 striated delta clouds shows that the striated deltas have a mean length of 1034 km and width of 537 km, and a striation wavelength of 74 km. Large parcel accelerations, nonlinear flow imbalance and active convection within the striated delta are features of the composite upper-tropospheric environment. Patterns of Q-vector illustrates the unique shape of striated delta clouds to be coincident with a delta-shaped forcing of adiabatic ascent in the poleward jet exit. One of the extratropical cyclones analysed and its associated striated delta is simulated with WRF-ARW both with and without diabatic heating. Both simulations produce pronounced gravity wave packets along the surface cold front, along the downstream upper jet axis and a delta-shaped packet in the lower stratosphere above the jet exit. Ray tracing identifies the source region of the waves in the stratosphere to be the upper jet. Vertically-radiating gravity waves originating in the vicinity of the jet during rapid extratropical cyclogenesis, propagate both upwards and downwards, imprinting striations onto the cloud in the jet exit and setting the spacing between the convective bands.&lt;/p&gt;

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 Characteristics and sources of gravity waves observed in NLC over Norway

2013 ◽  
Vol 13 (11) ◽  
pp. 29303-29331
Author(s):  
T. D. Demissie ◽  
P. J. Espy ◽  
N. H. Kleinknecht ◽  
M. Hatlen ◽  
N. Kaifler ◽  
...  
Keyword(s):  
Ray Tracing ◽  
Gravity Waves ◽  
Source Region ◽  
Digital Camera ◽  
Coastal Region ◽  
Primary Source ◽  
Noctilucent Cloud ◽  
The North ◽  
The Waves

Abstract. Four years of noctilucent cloud (NLC) images from an automated digital camera in Trondheim and results from a ray tracing model are used to extend the climatology of gravity waves to higher latitudes and to identify their sources at high latitudes during summertime. The climatology of the summertime gravity-waves detected in NLC between 64° and 74° N is similar to that observed between 60° and 64° N by Pautet et al. (2011). The direction of propagation of gravity waves observed in the NLC north of 64° N is a continuation of the north and northeast propagation as observed in south of 64° N. However, a unique population of fast, short wavelength waves propagating towards the SW is observed in the NLC, which is consistent with transverse instabilities generated in-situ by breaking gravity waves (Fritts et al., 2003). The relative amplitude of the waves observed in the NLC Mie-scatter have been combined with ray-tracing results to show that waves propagating from near the tropopause, rather than those resulting from secondary generation in the stratosphere or mesosphere, are more likely to be the sources of the prominent wave structures observed in the NLC. The coastal region of Norway along the latitude of 70° N is identified as the primary source region of the waves generated near the tropopause.

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