Numerical Simulation for Typhoon and Wave of Qiongzhou Strait

2016 ◽  
Author(s):  
Yanan Xu
Keyword(s):  
Southern China ◽  
Numerical Models ◽  
Wave Model ◽  
Numerical Approach ◽  
Wind Speeds ◽  
Qiongzhou Strait ◽  
Wave Heights ◽  
Significant Wave Heights ◽  
The Waves ◽  
Simulated Wind

Southern China has been subject to some of the deadliest typhoons in history with records going back over a thousand years. Before the large waves associated with a typhoon reach the mainland of China there is a delay between the typhoon reaching landfall and the time of the extreme waves arriving. This paper focuses on an approach to simulate this lag in the waves reaching landfall in the Qiongzhou Strait in southern China. A numerical approach has been adopted to simulate the typhoon and wave processes using a parametric typhoon model and the SWAN wave model. Two typhoon events are simulated (typhoon Kai-Tak in 2012 and typhoon Jebi in 2013) and used to tune the parameters for the numerical models. The simulated wind speeds and significant wave heights of the typhoon are compared with measured data. For the simulation of typhoon Kai-Tak, the correlation coefficient gives an 87% agreement between the simulated and measured values of wave height with a standard deviation of 0.29 m. For typhoon Jebi the fit is less good (66%). However, the simulation results have provided insight into improving the parametric typhoon model.

scholarly journals Impact of the Reduced Drag Coefficient on Ocean Wave Modeling under Hurricane Conditions

2008 ◽  
Vol 136 (3) ◽  
pp. 1217-1223 ◽  
Author(s):  
Il-Ju Moon ◽  
Isaac Ginis ◽  
Tetsu Hara
Keyword(s):  
Drag Coefficient ◽  
Hurricane Katrina ◽  
Wind Wave ◽  
Wave Model ◽  
High Wind ◽  
Model Surface ◽  
Wind Speeds ◽  
Tank Experiment ◽  
Wave Heights ◽  
Significant Wave Heights

Abstract Effects of new drag coefficient (Cd) parameterizations on WAVEWATCH III (WW3) model surface wave simulations are investigated. The new parameterizations are based on a coupled wind–wave model (CWW) and a wave tank experiment, and yields reduced Cd at high wind speeds. Numerical experiments for uniform winds and Hurricane Katrina (2005) indicate that the original Cd parameterization used in WW3 overestimates drag at high wind speeds compared to recent observational, theoretical, and numerical modeling results. Comparisons with buoy measurements during Hurricane Katrina demonstrate that WW3 simulations with the new Cd parameterizations yield more accurate significant wave heights compared to simulations with the original Cd parameterization, provided that accurate high-resolution wind forcing fields are used.

scholarly journals Analysis of extreme wave events on the southern coast of Brazil

2014 ◽  
Vol 14 (12) ◽  
pp. 3195-3205 ◽  
Author(s):  
P. V. Guimarães ◽  
L. Farina ◽  
E. E. Toldo Jr.
Keyword(s):  
Urban Areas ◽  
Rio Grande ◽  
Wave Model ◽  
Rio Grande Do Sul ◽  
Extreme Wave ◽  
Point Of Interest ◽  
Wave Heights ◽  
Significant Wave Heights ◽  
Buoy Data ◽  
The Waves

Abstract. Using the wave model SWAN (simulating waves nearshore), high waves on the southwestern Atlantic generated by extra-tropical cyclones are simulated from 2000 to 2010, and their impact on the Rio Grande do Sul (RS) coast is studied. The modeled waves are compared with buoy data and good agreement is found. The six extreme events in the period that presented significant wave heights above 5 m, on a particular point of interest, are investigated in detail. It is found that the cyclogenetic pattern between the latitudes 31.5 and 34° S is the most favorable for developing high waves. Hovmöller diagrams for deep water show that the region between the south of Rio Grande do Sul up to a latitude of 31.5° S is the most energetic during a cyclone's passage, although the event of May 2008 indicates that the location of this region can vary, depending on the cyclone's displacement. On the other hand, the Hovmöller diagrams for shallow water show that the different shoreface morphologies were responsible for focusing or dissipating the waves' energy; the regions found are in agreement with the observations of erosion and progradation regions. It can be concluded that some of the urban areas of the beaches of Hermenegildo, Cidreira, Pinhal, Tramandaí, Imbé and Torres have been more exposed during the extreme wave events on the Rio Grande do Sul coast, and are more vulnerable to this natural hazard.

Wave climate change in the Gulf of Bothnia

2021 ◽  
Author(s):  
Jan-Victor Björkqvist ◽  
Jani Särkkä ◽  
Hedi Kanarik ◽  
Laura Tuomi
Keyword(s):  
Climate Change ◽  
Wave Model ◽  
Wave Climate ◽  
Atmospheric Forcing ◽  
Simulation Data ◽  
Significant Wave ◽  
Gulf Of Bothnia ◽  
Wave Heights ◽  
Significant Wave Heights ◽  
Projected Changes

<p>Wave climate change in the Gulf of Bothnia in 2030–2059 was investigated using regional wave climate projections. For the simulations we used wave model WAM. As the atmospheric forcing for the wave model we had three global climate scenarios (HADGEM2-ES, MPI-ESM, EC-EARTH) downscaled with RCA4-NEMO regional model. The ice concentration for the wave model was obtained from NEMO ocean model simulations using the same atmospheric forcing. We used both RCP4.5 and RCP8.5 greenhouse gas scenarios. The spatial resolution of the simulation data was 1.8 km, enabling detailed analyses of the wave properties near the coast. From the simulation data we calculated statistics and return levels of significant wave heights using extreme value analysis, and assessed the projected changes in the wave climate in the Gulf of Bothnia. The projected increase in the significant wave heights is mainly due to the decreasing ice cover, especially in the Bothnian Bay. Projected changes in the most prevalent wind direction impacts the spatial pattern of the wave heights in the Bothnian Sea.</p>

scholarly journals Analysis of extreme wave events in the southern coast of Brazil

2014 ◽  
Vol 2 (6) ◽  
pp. 4363-4391 ◽  
Author(s):  
P. V. Guimarães ◽  
L. Farina ◽  
E. Toldo
Keyword(s):  
Urban Areas ◽  
Rio Grande ◽  
Rio Grande Do Sul ◽  
Extreme Wave ◽  
Point Of Interest ◽  
Wave Heights ◽  
Significant Wave Heights ◽  
Buoy Data ◽  
The Waves ◽  
Good Agreement

Abstract. Using the model SWAN, high waves on the Southwestern Atlantic generated by extra-tropical cyclones are simulated from 2000 to 2010 and their impact on the Rio Grande do Sul coast is studied. The modeled waves are compared with buoy data and good agreement is found. The six extreme events in the period which presented significant wave heights above 5 m, on a particular point of interest, are investigated in detail. It is found that the cyclogenetic pattern between the latitudes 31.5 and 34° S, is the most favorable for developing high waves. Hovmöller diagrams for deep water show that the region between the south of Rio Grande do Sul up to latitude 31.5° S is the most energetic during a cyclone's passage, although the event of May 2008 indicate that the location of this region can vary, depending on the cyclone's displacement. On the oher hand, the Hovmöller diagrams for shallow water show that the different shoreface morphologies were responsable for focusing or dissipating the waves' energy; the regions found are in agreement with the observations of erosion and progradation regions. It can be concluded that some of the urban areas of the beaches of Hermenegildo, Cidreira, Pinhal, Tramandaí, Imbé and Torres have been more exposed during the extreme wave events at Rio Grande do Sul coast, and are more vulnerable to this natural hazard.

scholarly journals UPWIND TRAVEL OF REFLECTED WAVES

1968 ◽  
Vol 1 (11) ◽  
pp. 14
Author(s):  
E.P. Richey
Keyword(s):  
Wind Waves ◽  
Full Scale Test ◽  
Deep Lake ◽  
Reflected Waves ◽  
Wind Speeds ◽  
Wave Characteristics ◽  
Wave Heights ◽  
Scale Test ◽  
Floating Bridges ◽  
The Waves

Wind waves in a lake have been observed to reflect from a barrier and to travel upwind for considerable distances. A model has been devised which provides a means of predicting the decay of these waves as a function of wind speed and direction with respect to the barrier. Two floating bridges across a deep lake have formed a convenient, full-scale test basin for the formation and observation of the reflected waves under a range of wind speeds and directions. Wave characteristics have been measured to a limited extent by photographic means, a portable wave probe and visually to provide seme verification of the results computed from the model. The measured and the predicted wave heights and the zones influenced by the waves were found to be in general qualitative agreement.

Measured Metocean Characteristics of Gulf of Mexico Hurricanes

2015 ◽  
Author(s):  
George Z. Forristall ◽  
Jason McConochie
Keyword(s):  
Gulf Of Mexico ◽  
Wave Height ◽  
Storm Track ◽  
Significant Wave ◽  
Wind Speeds ◽  
Hurricane Wind ◽  
Wave Parameters ◽  
Wave Heights ◽  
Significant Wave Heights ◽  
Buoy Data

A wealth of Gulf of Mexico hurricane wind and wave data has been measured in recent years. We have constructed a database that combines HURDAT storm track information with NDBC buoy data for the years 1978–2010. HURDAT contains 141 storms for that period of which 67 had measured significant wave heights greater than 5 m. Industry measurements in Hurricanes Camille, Lili, Ivan, Katrina, Rita, Gustav and Ike have been added to the buoy data. We have used this data base to study the relationships between wind and wave parameters in hurricanes. Specifically, we have calculated regressions and equal probability contours for significant wave height and peak spectral periods, first and second moment periods, wave height and Jonswap gamma values, wind speeds and wave heights, and wave and wind directions. All of these calculations have been done for azimuthal quadrants of the storm and radial distances near and far from the storm center.

Metocean Design Criteria Considerations in South China Sea by Adopting Multivariate Extreme Value Theory

2017 ◽  
Author(s):  
Ping Li ◽  
Qi Zhu ◽  
Chunqi Zhou ◽  
Linbin Li ◽  
Hongtao Li
Keyword(s):  
Probability Distribution ◽  
South China Sea ◽  
Joint Probability ◽  
Extreme Value Distribution ◽  
Extreme Value ◽  
Design Criteria ◽  
Joint Probability Distribution ◽  
Wind Speeds ◽  
Wave Heights ◽  
Significant Wave Heights

The proper determination of metocean design criteria is critical for offshore structures. We study in this paper the univariate and multivariate compound extreme value theories and their applications to metocean data. Firstly, we adopt Compound Extreme Value Distribution (CEVD) method to derive the marginal distributions of wind speeds and significant wave heights respectively. Modelling uncertainties are considered with different distribution models. Secondly, the basic theory of Bivariate Compound Extreme Value Distribution (BCEVD), especially Poisson Bivariate Gumbel Logistic Distribution (PBGLD) is reviewed and utilized to analyze the joint probability distribution of significant wave heights and the concomitant wind speeds. Thirdly, Extreme Water Level (EWL) which is defined as the combination of wave crest, surge height and tidal elevation, is analyzed. We treat astronomical tide as a deterministic phenomenon and estimate the joint probability distribution of crest heights and storm surges. Case studies are given for picked position points in Northern South China Sea with 40 years hindcasted data. The results of this paper could give some knowledge for the determination and refinement of metocean design parameters.

scholarly journals Determination of Significant Wave Heights Using Damping Coefficients of Attenuated GNSS SNR Data from Static and Kinematic Observations

2019 ◽  
Vol 11 (4) ◽  
pp. 409 ◽  
Author(s):  
Ole Roggenbuck ◽  
Jörg Reinking ◽  
Tomke Lambertus
Keyword(s):  
Signal To Noise Ratio ◽  
Wave Model ◽  
Significant Wave ◽  
Sea Surface Roughness ◽  
Wave Heights ◽  
Gnss Reflectometry ◽  
Significant Wave Heights ◽  
Using Data ◽  
Ocean Remote Sensing

Currently, GNSS reflectometry based on the signal-to-noise ratio (SNR) has become an established tool in ocean remote sensing. Here, the distance between an antenna and the water surface is measured by analyzing the oscillation of the SNR observation. Due to the antenna gain pattern, this oscillation is more pronounced for satellite signals coming from low elevation angles. Additionally, the sea surface roughness is related to the attenuation of the SNR oscillation. Hence, the significant wave height (SWH) can be estimated by analyzing the SNR signal. In this work, a method is presented with which the SWH can be calculated from the attenuation’s damping coefficient of the SNR observations measured with surface-based receivers. The method’s usability is demonstrated using data from a static antenna operated in the German Bight and with data from a ship-based antenna. The estimated SWH values were validated against numerical wave model data. For both experiments, a high correlation was found.

scholarly journals Improving Altimeter Wind Speed Retrievals Using Ocean Wave Parameters

2020 ◽  
Author(s):  
Haoyu Jiang ◽  
Hao Zheng ◽  
Lin Mu
Keyword(s):  
Surface Wind ◽  
Sea Surface ◽  
Atmospheric Parameters ◽  
Sea Temperature ◽  
Wind Speeds ◽  
Sea Surface Wind ◽  
Wave Heights ◽  
Data Source ◽  
Significant Wave Heights ◽  
The Impact

Spaceborne altimeters are an important data source for obtaining global sea surface wind speeds (U10). Although many altimeter U10 algorithms have been proposed and they perform well, there is still room for improvement. In this study, the data from ten altimeters were collocated with buoys to investigate the error of the altimeter U10 retrievals. The U10 residuals were found to be significantly dependent on many oceanic and atmospheric parameters. Because these oceanic and atmospheric parameters are inter-correlated, an asymptotic strategy was used to isolate the impact of different parameters and establish a neural-network-based correction model of altimeter U10. The results indicated that significant wave heights and mean wave periods are effective in correcting U10 retrievals, probably due to the tilting modulation of long-waves on the sea surface. After the wave correction, the root-mean-square error of the retrieved U10 was reduced from 1.42 m/s to 1.24 m/s and the impacts of thermodynamic parameters, such as sea surface (air) temperate, became negligible. The U10 residuals after correction showed that the atmospheric instability can lead to errors on extrapolated buoy U10. The buoy measurements with large air-sea temperature differences need to be excluded in the Cal/Val of remotely sensed U10.

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