scholarly journals The Partial Reflection of Tsunami-Generated Gravity Waves

2014 ◽  
Vol 71 (9) ◽  
pp. 3416-3426 ◽  
Author(s):  
Dave Broutman ◽  
Stephen D. Eckermann ◽  
Douglas P. Drob
Keyword(s):  
Wave Propagation ◽  
Gravity Wave ◽  
Gravity Waves ◽  
Vertical Profile ◽  
Turning Points ◽  
Lower Thermosphere ◽  
Ocean Surface ◽  
Wave Transmission ◽  
Sumatra Earthquake ◽  
Partial Reflection

Abstract A vertical eigenfunction equation is solved to examine the partial reflection and partial transmission of tsunami-generated gravity waves propagating through a height-dependent background atmosphere from the ocean surface into the lower thermosphere. There are multiple turning points for each vertical eigenfunction (at least eight in one example), yet the wave transmission into the thermosphere is significant. Examples are given for gravity wave propagation through an idealized wind jet centered near the mesopause and through a realistic vertical profile of wind and temperature relevant to the tsunami generated by the Sumatra earthquake on 26 December 2004.

scholarly journals Gravity wave propagation through a large semidiurnal tide and instabilities in the mesosphere and lower thermosphere during the winter 2003 MaCWAVE rocket campaign

2006 ◽  
Vol 24 (4) ◽  
pp. 1199-1208 ◽  
Author(s):  
B. P. Williams ◽  
D. C. Fritts ◽  
C. Y. She ◽  
R. A. Goldberg
Keyword(s):  
Wave Propagation ◽  
Gravity Wave ◽  
Gravity Waves ◽  
Lower Thermosphere ◽  
Semidiurnal Tide ◽  
Frequency Spectra ◽  
Mesosphere And Lower Thermosphere ◽  
Using Data ◽  
Wind Profiles ◽  
Full Temperature

Abstract. The winter MaCWAVE (Mountain and convective waves ascending vertically) rocket campaign took place in January 2003 at Esrange, Sweden and the ALOMAR observatory in Andenes, Norway. The campaign combined balloon, lidar, radar, and rocket measurements to produce full temperature and wind profiles from the ground to 105 km. This paper will investigate gravity wave propagation in the mesosphere and lower thermosphere using data from the Weber sodium lidar on 28–29 January 2003. A very large semidiurnal tide was present in the zonal wind above 80 km that grew to a 90 m/s amplitude at 100 km. The superposition of smaller-scale gravity waves and the tide caused small regions of possible convective or shear instabilities to form along the downward progressing phase fronts of the tide. The gravity waves had periods ranging from the Nyquist period of 30 min up to 4 h, vertical wavelengths ranging from 7 km to more than 20 km, and the frequency spectra had the expected –5/3 slope. The dominant gravity waves had long vertical wavelengths and experienced rapid downward phase progression. The gravity wave variance grew exponentially with height up from 86 to 94 km, consistent with the measured scale height, suggesting that the waves were not dissipated strongly by the tidal gradients and resulting unstable regions in this altitude range.

scholarly journals Nonlinear Simulations of GravityWave Tunneling and Breaking over Auckland Island

2021 ◽  
Author(s):  
Tyler Mixa ◽  
Andreas Dörnbrack ◽  
Markus Rapp
Keyword(s):  
Wave Propagation ◽  
Gravity Wave ◽  
Gravity Waves ◽  
Lower Thermosphere ◽  
Polar Night ◽  
Auckland Island ◽  
Mesospheric Temperature ◽  
Nonlinear Simulations ◽  
Mesosphere And Lower Thermosphere

AbstractHorizontally dispersing gravity waves with horizontal wavelengths of 30 – 40 km were observed at mesospheric altitudes over Auckland Island by the airborne advanced mesospheric temperature mapper during a DEEPWAVE research flight on 14 July 2014. A 3D nonlinear compressible model is used to determine which propagation conditions enabled gravity wave penetration into the mesosphere and how the resulting instability characteristics led to widespread momentum deposition. Results indicate that linear tunneling through the polar night jet enabled quick gravity wave propagation from the surface up to the mesopause, while subsequent instability processes reveal large rolls that formed in the negative shear above the jet maximum and led to significant momentum deposition as they descended. This study suggests that gravity wave tunneling is a viable source for this case and other deep propagation events reaching the mesosphere and lower thermosphere.

The Momentum Budget in the Stratosphere, Mesosphere, and Lower Thermosphere. Part II: The In Situ Generation of Gravity Waves

2018 ◽  
Vol 75 (10) ◽  
pp. 3635-3651 ◽  
Author(s):  
Ryosuke Yasui ◽  
Kaoru Sato ◽  
Yasunobu Miyoshi
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Lower Thermosphere ◽  
Shear Instability ◽  
Wave Forcing ◽  
Momentum Budget ◽  
Mesosphere And Lower Thermosphere ◽  
In Situ Generation ◽  
Mlt Region

The contributions of gravity waves to the momentum budget in the mesosphere and lower thermosphere (MLT) is examined using simulation data from the Ground-to-Topside Model of Atmosphere and Ionosphere for Aeronomy (GAIA) whole-atmosphere model. Regardless of the relatively coarse model resolution, gravity waves appear in the MLT region. The resolved gravity waves largely contribute to the MLT momentum budget. A pair of positive and negative Eliassen–Palm flux divergences of the resolved gravity waves are observed in the summer MLT region, suggesting that the resolved gravity waves are likely in situ generated in the MLT region. In the summer MLT region, the mean zonal winds have a strong vertical shear that is likely formed by parameterized gravity wave forcing. The Richardson number sometimes becomes less than a quarter in the strong-shear region, suggesting that the resolved gravity waves are generated by shear instability. In addition, shear instability occurs in the low (middle) latitudes of the summer (winter) MLT region and is associated with diurnal (semidiurnal) migrating tides. Resolved gravity waves are also radiated from these regions. In Part I of this paper, it was shown that Rossby waves in the MLT region are also radiated by the barotropic and/or baroclinic instability formed by parameterized gravity wave forcing. These results strongly suggest that the forcing by gravity waves originating from the lower atmosphere causes the barotropic/baroclinic and shear instabilities in the mesosphere that, respectively, generate Rossby and gravity waves and suggest that the in situ generation and dissipation of these waves play important roles in the momentum budget of the MLT region.

Effects of Nonlinearity on Convectively Forced Internal Gravity Waves: Application to a Gravity Wave Drag Parameterization

2008 ◽  
Vol 65 (2) ◽  
pp. 557-575 ◽  
Author(s):  
Hye-Yeong Chun ◽  
Hyun-Joo Choi ◽  
In-Sun Song
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Momentum Flux ◽  
Lower Thermosphere ◽  
Internal Gravity Waves ◽  
Wave Drag ◽  
Scale Factor ◽  
Wide Range ◽  
Flux Spectrum ◽  
Diabatic Forcing

Abstract In the present study, the authors propose a way to include a nonlinear forcing effect on the momentum flux spectrum of convectively forced internal gravity waves using a nondimensional numerical model (NDM) in a two-dimensional framework. In NDM, the nonlinear forcing is represented by nonlinear advection terms multiplied by the nonlinearity factor (NF) of the thermally induced internal gravity waves for a given specified diabatic forcing. It was found that the magnitudes of the waves and resultant momentum flux above the specified forcing decrease with increasing NF due to cancellation between the two forcing mechanisms. Using the momentum flux spectrum obtained by the NDM simulations with various NFs, a scale factor for the momentum flux, normalized by the momentum flux induced by diabatic forcing alone, is formulated as a function of NF. Inclusion of the nonlinear forcing effect into current convective gravity wave drag (GWD) parameterizations, which consider diabatic forcing alone by multiplying the cloud-top momentum flux spectrum by the scale factor, is proposed. An updated convective GWD parameterization using the scale factor is implemented into the NCAR Whole Atmosphere Community Climate Model (WACCM). The 10-yr simulation results, compared with those by the original convective GWD parameterization considering diabatic forcing alone, showed that the magnitude of the zonal-mean cloud-top momentum flux is reduced for wide range of phase speed spectrum by about 10%, except in the middle latitude storm-track regions where the cloud-top momentum flux is amplified. The zonal drag forcing is determined largely by the wave propagation condition under the reduced magnitude of the cloud-top momentum flux, and its magnitude decreases in many regions, but there are several areas of increasing drag forcing, especially in the tropical upper mesosphere and lower thermosphere.

scholarly journals Gravity wave transmission diagram

2015 ◽  
Vol 33 (12) ◽  
pp. 1479-1484 ◽  
Author(s):  
Y. Tomikawa
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Phase Speed ◽  
Propagation Direction ◽  
Wave Transmission ◽  
Vertical Shear ◽  
Horizontal Wind ◽  
Wave Power ◽  
Power Spectral ◽  
Horizontal Wavelength

Abstract. A new method of obtaining power spectral distribution of gravity waves as a function of ground-based horizontal phase speed and propagation direction from airglow observations has recently been proposed. To explain gravity wave power spectrum anisotropy, a new gravity wave transmission diagram was developed in this study. Gravity wave transmissivity depends on the existence of critical and turning levels for waves that are determined by background horizontal wind distributions. Gravity wave transmission diagrams for different horizontal wavelengths in simple background horizontal winds with constant vertical shear indicate that the effects of the turning level reflection are significant and strongly dependent on the horizontal wavelength.

scholarly journals Gravity wave propagation and dissipation from the stratosphere to the lower thermosphere

2009 ◽  
Vol 114 (D11) ◽  
Author(s):  
Xian Lu ◽  
Alan Z. Liu ◽  
Gary R. Swenson ◽  
Tao Li ◽  
Thierry Leblanc ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Gravity Wave ◽  
Lower Thermosphere

scholarly journals Diurnal variation of short-period (20–120 min) gravity waves in the equatorial Mesosphere and Lower Thermosphere and its relation to deep tropical convection

2011 ◽  
Vol 29 (4) ◽  
pp. 623-629 ◽  
Author(s):  
N. Venkateswara Rao ◽  
Y. Shibagaki ◽  
T. Tsuda
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Theoretical Calculations ◽  
Lower Thermosphere ◽  
Tropical Convection ◽  
Peak Activity ◽  
Medium Frequency ◽  
Short Period ◽  
Mesosphere And Lower Thermosphere ◽  
Mf Radar

Abstract. We study short period gravity waves (20–120 min) in the equatorial Mesosphere and Lower Thermosphere (MLT) using a Medium Frequency (MF) radar at Pameungpeuk (7.4° S, 107.4° E), Indonesia. In particular, we study local time and seasonal variation of the gravity wave variance and its relation to tropical convection. The gravity wave variance at 88 km enhances between 20:00 LT and 07:00 LT, with a peak at 02:00–03:00 LT. The enhancement is mainly observed during February–April and September–October and shows inter-annual variability. Convective activity over the same location persists from 16:00–21:00 LT with a peak activity ~18:00 LT and enhances between November–April. Time delay between the peak of convection and that of gravity wave activity ranges 1–15 h, which is consistent with theoretical calculations and previous reports based on reverse ray tracing analysis.

scholarly journals Sensitivity of middle atmospheric temperature and circulation in the UIUC GCM to the treatment of subgrid-scale gravity-wave breaking

2006 ◽  
Vol 6 (5) ◽  
pp. 9085-9121 ◽  
Author(s):  
F. Yang ◽  
M. E. Schlesinger ◽  
E. V. Rozanov ◽  
N. Andronova ◽  
V. A. Zubov ◽  
...  
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
General Circulation ◽  
Lower Thermosphere ◽  
Atmospheric Temperature ◽  
Mean Flow ◽  
Quasi Biennial Oscillation ◽  
Warm Bias ◽  
Wave Forcing ◽  
Budget Analysis

Abstract. The sensitivity of the middle atmospheric temperature and circulation to the treatment of mean-flow forcing due to breaking gravity waves at the sub-grid scale was investigated using the University of Illinois at Urbana-Champaign 40-layer General Circulation Model (GCM). The gravity-wave forcing was represented either by Rayleigh friction or by a detailed parameterization scheme with different sets of parameters. The modeled middle atmospheric temperature and circulation exhibit large sensitivity to the parameterized sub-grid gravity-wave forcing. A large warm bias of up to 50°C was found in the model's summer upper mesosphere and lower thermosphere. This warm bias was caused by the inability of the GCM to simulate the reversal of the zonal winds from easterly to westerly crossing the mesopause in the summer hemisphere. Attempts were made to slow down the easterly winds near the mesopause and to reduce the warm bias. The GCM was able to realistically simulate the semi-annual oscillation in the upper stratosphere and lower mesosphere with observational constraints on certain parameter values, but failed to simulate the quasi-biennial oscillation in any of the experiments. Budget analysis indicates that in the middle atmosphere the forces that act to maintain a steady zonal-mean zonal wind are primarily those associated with the meridional transport circulation and breaking gravity waves. Contributions from the interaction of the model-resolved eddies with the mean flow are secondary.

scholarly journals Assessing the role of planetary and gravity waves on the vertical structure of ozone over central Europe

2018 ◽  
Author(s):  
Peter Križan
Keyword(s):  
Gravity Wave ◽  
Central Europe ◽  
Gravity Waves ◽  
Vertical Profile ◽  
Planetary Wave ◽  
Annual Variation ◽  
Ozone Profile ◽  
Vertical Ozone Profile ◽  
Vertical Ozone

Abstract. Planetary and gravity waves play an important role in the dynamics of the atmosphere. They are present in the atmospheric distribution of temperature, wind and ozone content. These waves are detectable also in the vertical profile of ozone and they cause its undulation. One of the structures occurring in the vertical ozone profile is laminae, which are narrow layers of enhanced or depleted ozone concentration in the vertical ozone profile. They are connected with the total amount of ozone in the atmosphere and with the activity of the planetary and the gravity waves. The aim of this paper is quantifying these processes in the central Europe. We compare the occurrence of laminae induced by planetary waves (PL) with the occurrence of these induced by gravity waves (GL). We show that the PL are 3–5 times more frequent than the gravity wave ones. There is a strong annual variation of PL, while GL exhibit only a very weak variation. With the increasing lamina size the share of GL decreases and the share of PL increases. The vertical profile of lamina occurrence is different for small planetary wave and gravity wave laminae. The trend of large lamina occurrence frequency is given by the trend in PL, not by GL.

scholarly journals Multi-instrument gravity-wave measurements over Tierra del Fuego and the Drake Passage – Part 1: Potential energies and vertical wavelengths from AIRS, COSMIC, HIRDLS, MLS-Aura, SAAMER, SABER and radiosondes

2015 ◽  
Vol 8 (7) ◽  
pp. 6797-6876 ◽  
Author(s):  
C. J. Wright ◽  
N. P. Hindley ◽  
A. C. Moss ◽  
N. J. Mitchell
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Wave Packets ◽  
Lower Thermosphere ◽  
Drake Passage ◽  
Tierra Del Fuego ◽  
Meteor Radar ◽  
Diverse Range ◽  
Terrestrial Atmosphere ◽  
Wide Range

Abstract. Gravity waves in the terrestrial atmosphere are a vital geophysical process, acting to transport energy and momentum on a wide range of scales and to couple the various atmospheric layers. Despite the importance of these waves, the many studies to date have often exhibited very dissimilar results, and it remains unclear whether these differences are primarily instrumental or methodological. Here, we address this problem by comparing observations made by a diverse range of the most widely-used gravity wave resolving instruments in a common geographic region around the southern Andes and Drake Passage, an area known to exhibit strong wave activity. Specifically, we use data from three limb-sounding radiometers (MLS-Aura, HIRDLS and SABER), the COSMIC GPS-RO constellation, a ground-based meteor radar, the AIRS infrared nadir sounder and radiosondes to examine the gravity wave potential energy (GWPE) and vertical wavelengths (λz) of individual gravity wave packets from the lower troposphere to the edge of the lower thermosphere. Our results show important similarities and differences. Limb sounder measurements show high intercorrelation, typically > 0.80 between any instrument pair. Meteor-radar observations agree in form with the limb sounders, despite vast technical differences. AIRS and radiosonde observations tend to be uncorrelated or anticorrelated with the other datasets, suggesting very different behaviour of the wave field in the different spectral regimes accessed by each instrument. Except in spring, we see little dissipation of GWPE throughout the stratosphere and lower mesosphere. Observed GWPE for individual wave packets exhibits a log-normal distribution, with short-timescale intermittency dominating over a well-repeated monthly-median seasonal cycle. GWPE and λz exhibit strong correlations with the stratospheric winds, but not with local surface winds. Our results provide guidance for interpretation and intercomparison of such datasets in their full context, and reinforce the vital point that no one dataset can represent the whole spectrum of gravity waves in the terrestrial atmosphere.

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