scholarly journals The South Georgia Wave Experiment (SG-WEX): radiosonde observations of gravity waves in the lower stratosphere. Part I: Energy density, momentum flux and wave propagation direction

2017 ◽  
Vol 143 (709) ◽  
pp. 3279-3290 ◽  
Author(s):  
Tracy Moffat-Griffin ◽  
Corwin J. Wright ◽  
Andrew C. Moss ◽  
John C. King ◽  
Steve R. Colwell ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Energy Density ◽  
Gravity Waves ◽  
Momentum Flux ◽  
Lower Stratosphere ◽  
Propagation Direction ◽  
The South ◽  
Wave Propagation Direction ◽  
South Georgia ◽  
Wave Experiment

scholarly journals The South Georgia Wave Experiment: A Means for Improved Analysis of Gravity Waves and Low-Level Wind Impacts Generated from Mountainous Islands

2018 ◽  
Vol 99 (5) ◽  
pp. 1027-1040 ◽  
Author(s):  
D. R. Jackson ◽  
A. Gadian ◽  
N. P. Hindley ◽  
L. Hoffmann ◽  
J. Hughes ◽  
...  
Keyword(s):  
High Resolution ◽  
Gravity Waves ◽  
Numerical Models ◽  
Small Island ◽  
Small Scale ◽  
The South ◽  
South Georgia ◽  
Low Level ◽  
Wave Experiment ◽  
Realistic Representation

AbstractGravity waves (GWs) play an important role in many atmospheric processes. However, the observation-based understanding of GWs is limited, and representing them in numerical models is difficult. Recent studies show that small islands can be intense sources of GWs, with climatologically significant effects on the atmospheric circulation. South Georgia, in the South Atlantic, is a notable source of such “small island” waves. GWs are usually too small scale to be resolved by current models, so their effects are represented approximately using resolved model fields (parameterization). However, the small-island waves are not well represented by such parameterizations, and the explicit representation of GWs in very-high-resolution models is still in its infancy. Steep islands such as South Georgia are also known to generate low-level wakes, affecting the flow hundreds of kilometers downwind. These wakes are also poorly represented in models.We present results from the South Georgia Wave Experiment (SG-WEX) for 5 July 2015. Analysis of GWs from satellite observations is augmented by radiosonde observations made from South Georgia. Simulations were also made using high-resolution configurations of the Met Office Unified Model (UM). Comparison with observations indicates that the UM performs well for this case, with realistic representation of GW patterns and low-level wakes. Examination of a longer simulation period suggests that the wakes generally are well represented by the model. The realism of these simulations suggests they can be used to develop parameterizations for use at coarser model resolutions.

Study of the gravity wave propagation direction observed by airglow imaging in the South American sector

2005 ◽  
Author(s):  
Amauri F. Medeiros ◽  
Hisao Takahashi ◽  
Ricardo A. Buriti ◽  
Kiosthenes. M. Pinheiro and Delano Gobbi
Keyword(s):  
Wave Propagation ◽  
Gravity Wave ◽  
Propagation Direction ◽  
South American ◽  
The South ◽  
Wave Propagation Direction

Study of the gravity wave propagation direction observed by airglow imaging in the South American sector

2005 ◽  
Author(s):  
Amauri F. Medeiros ◽  
Hisao Takahashi ◽  
Ricardo A. Buriti ◽  
Kiosthenes. M. Pinheiro ◽  
Delano Gobbi
Keyword(s):  
Wave Propagation ◽  
Gravity Wave ◽  
Propagation Direction ◽  
South American ◽  
The South ◽  
Wave Propagation Direction

scholarly journals Tidal Modulation of Surface Gravity Waves in the Gulf of Maine

2018 ◽  
Vol 48 (10) ◽  
pp. 2305-2323 ◽  
Author(s):  
Pengcheng Wang ◽  
Jinyu Sheng
Keyword(s):  
Wave Propagation ◽  
Gravity Waves ◽  
Gulf Of Maine ◽  
Circulation Model ◽  
Tidal Currents ◽  
Propagation Direction ◽  
Surface Gravity ◽  
Wave Propagation Direction ◽  
Surface Gravity Waves ◽  
Energy Convergence

AbstractThis study examines the tidal modulation of surface gravity waves in the Gulf of Maine (GoM) by using in situ observations and numerical model results. Analysis of observational data demonstrates significant semidiurnal tidal modulations in the mean wave variables for swell-dominated waves in the region. The observed tidal modulation features significant spatial–temporal variabilities, with large magnitudes near the mouth of the GoM. Observations also demonstrate unusual timing of the maximum modulation of significant wave height Hs in the following tidal currents. The coupled wave–circulation model successfully reproduces the observed tidal modulation and the associated spatial–temporal variabilities. Model results demonstrate that the maximum Hs modulations are first generated during the maximum flood tide or ebb tide near the mouth of the GoM and then propagate onto the inner gulf. Around the mouth of the GoM, tidal currents have strong spatial gradients, resulting in great effects of current-induced convergence, refraction, and wavenumber shift. The tidal modulation in Hs generated by convergence (10%–14%) is less affected by the wave propagation direction than the modulation generated by the wavenumber shift (6%–10%) and refraction (4%–20%). The latter modulation varies significantly with changes in the wave propagation direction. In addition, current-enhanced dissipation becomes important during high winds, which reduces at least one-half of the Hs modulation during the study period. The observed unusual timing of the maximum Hs modulation in the following tidal currents can be mostly explained by the convergence and wavenumber shift associated with wave-energy convergence and energy transfer from currents to waves in spatially decelerating currents.

scholarly journals Lamb Wave Directional Sensing with Piezoelectric Fiber Rosette in Structure Health Monitoring

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Songlai Wang ◽  
Wanrong Wu ◽  
Yiping Shen ◽  
Hui Li ◽  
Binlong Tang
Keyword(s):  
Wave Propagation ◽  
Health Monitoring ◽  
Lamb Wave ◽  
Estimation Method ◽  
Propagation Direction ◽  
Response Amplitude ◽  
Piezoelectric Sensors ◽  
Wave Propagation Direction ◽  
Lamb Wave Propagation ◽  
Piezoelectric Fiber

Directional piezoelectric sensors can detect the Lamb wave propagation direction to locate damage in structural health monitoring (SHM). The directivity of the round piezoelectric fiber is exploited with a 0°/45°/90° rosette configuration to acquire flexural Lamb wave signals. The directional response of the piezoelectric fiber under narrowband tone-burst excitation is theoretically deduced. Experimental tests are conducted to demonstrate the directivity and the frequency response property of the piezoelectric fiber under different excitation central frequencies in comparison with the MFC, rectangular piezoelectric sheet, and circular piezoelectric disc. Continuous wavelet transform (CWT) is applied to extract the maximum response amplitude information of the acquired Lamb wave signal at a central frequency. Experimental test results indicate that the piezoelectric fiber is capable to be used as a Lamb wave directional sensor than other piezoelectric sensors. A numerical estimation method for the Lamb wave propagation direction is proposed by defining an error function between the theoretical and experimental normalized response amplitude. The proposed method is generally applicable for different rosette configurations. Experimental results validate the accuracy of the proposed estimation method. The research results are significant to design or select the piezoelectric sensor to measure Lamb wave signals.

Determination of Ocean Wave Propagation Direction Based on Azimuth Scanning Mode

2011 ◽  
Vol 8 (6) ◽  
pp. 1155-1159
Author(s):  
Liu Fan ◽  
Zhao Fengjun ◽  
Deng Yunkai ◽  
Yu Weidong ◽  
Chen Yongqiang ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Propagation Direction ◽  
Ocean Wave ◽  
Wave Propagation Direction

scholarly journals Asymmetric gravity–capillary solitary waves on deep water

2014 ◽  
Vol 759 ◽  
Author(s):  
Z. Wang ◽  
J.-M. Vanden-Broeck ◽  
P. A. Milewski
Keyword(s):  
Wave Propagation ◽  
Solitary Waves ◽  
Travelling Wave ◽  
Propagation Direction ◽  
Travelling Wave Solutions ◽  
Two Dimensional ◽  
Bifurcation Curve ◽  
Wave Propagation Direction ◽  
Wave Solutions ◽  
Deep Fluid

AbstractWe present new families of gravity–capillary solitary waves propagating on the surface of a two-dimensional deep fluid. These spatially localised travelling-wave solutions are non-symmetric in the wave propagation direction. Our computation reveals that these waves appear from a spontaneous symmetry-breaking bifurcation, and connect two branches of multi-packet symmetric solitary waves. The speed–energy bifurcation curve of asymmetric solitary waves features a zigzag behaviour with one or more turning points.

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