scholarly journals Impact of Extratropical Cyclone Intensity and Speed on the Extreme Wave Trends in the Atlantic Ocean

2021 ◽  
Author(s):  
Carolina Barnez Gramcianinov ◽  
Ricardo de Camargo ◽  
Ricardo Martins Campos ◽  
Carlos Guedes Soares ◽  
Pedro Leite da Silva Dias
Keyword(s):  
Hot Spot ◽  
Storm Track ◽  
Ocean Surface ◽  
Relative Vorticity ◽  
Extratropical Cyclone ◽  
Mature Stage ◽  
Western Boundary ◽  
Extreme Waves ◽  
Extreme Wave ◽  
Cyclone Intensity

Abstract This work analyzes the extratropical cyclone-related extreme waves in the ocean surface and their trends in the North and South Atlantic Oceans. Atmospheric and ocean wave products are obtained from ERA5, from 1979 to 2020 with 1-hourly outputs, covering 42 years with the present climate changes evaluated by the difference between the two 21-years time slices. The cyclones are tracked through the relative vorticity at 850 hPa and then associated with extreme wave events using an automated scheme that searches for an extreme wave region 1500 km from the centre of the cyclone, following criteria that exclude possible swell dominated events. The hot-spot regions of cyclone-related waves occurrence found by the method are in agreement with previous studies and are related to the cyclogenesis region and storm track orientation. Most cyclones associated with extreme wave events are generated in the western boundary of the domains. The east-poleward side of the ocean basins presents the highest density of occurrences related to the higher density of cyclone track and the dominance of more mature stage cyclones while in the west side prevail systems on developing stages, with notable propagating fronts and consequently, lower wind persistence. Changes in occurrence cannot be explained just by the storm track variation during the period due to the lack of statistical confidence. However, the wave occurrence responds to changes in the cyclone intensity, modulated by cyclone displacement speed. Regions with an increase of extreme waves are related to the effect of more intense cyclones or cyclones with slower propagation, being the last associated with a longer interaction of winds with the ocean surface.

Comparison Between ERA5 and CFS Datasets of Extratropical Cyclones Associated With Extreme Wave Events in the Atlantic Ocean

2020 ◽  
Author(s):  
C. B. Gramcianinov ◽  
R. M. Campos ◽  
C. Guedes Soares ◽  
R. de Camargo
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Storm Track ◽  
Wave Climate ◽  
Relative Vorticity ◽  
Extratropical Cyclones ◽  
Extreme Waves ◽  
Extreme Wave ◽  
Cyclone Intensity ◽  
Spatial Coverage

Abstract Atmospheric and ocean datasets using numerical modeling allied to data assimilation are valuable tools for planning and maintaining marine activities, particularly due to their spatial coverage and resolution. However, even modern analyses and reanalyses present critical errors where cyclonic winds are often underestimated in some locations, leading to issues in wind-wave climate hindcasts and forecasts. This work aims to evaluate two of the newest datasets available regarding their ability to reproduce extratropical cyclone tracks associated with extreme waves in the Atlantic Ocean. The analysis is focused on the storm track position and cyclone intensity, two important features that control the wave climate. The datasets used are the ECMWF’s ERA5 and NCEP’s CFSv2. The cyclones are identified and compared between 2011 and 2018 using the relative vorticity at 850hPa and the intensity is measured through the 10-meters wind speed. The results show that the differences in track density exist mainly in coastal areas and they can be related to the coarser resolution of CFSv2 compared to ERA5. CFSv2 presents a higher number of cyclones associated with extreme wave events in the South and North Atlantic, corresponding to 87.1% and 89.2% of the cyclones identified, while ERA5 presents 66.6% and 59.5% respectively. The maximum intensity distribution shows that CFSv2 tends to produce more intense cyclones than ERA5, even for identical storms in the datasets. The distances of matching cyclones in the two datasets are around 0.5°.

scholarly journals EXTREME WAVE PRESSURES AND LOADS ON A PILE-SUPPORTED WHARF DECK - INFLUENCES OF AIR GAP AND WAVE DIRECTION

2018 ◽  
pp. 5
Author(s):  
Andrew Cornett
Keyword(s):  
Offshore Structures ◽  
Model Tests ◽  
Scale Model ◽  
Extreme Waves ◽  
Wave Direction ◽  
Coastal Structures ◽  
Extreme Wave ◽  
Wave Impact ◽  
The Past ◽  
Water Depths

Many deck-on-pile structures are located in shallow water depths at elevations low enough to be inundated by large waves during intense storms or tsunami. Many researchers have studied wave-in-deck loads over the past decade using a variety of theoretical, experimental, and numerical methods. Wave-in-deck loads on various pile supported coastal structures such as jetties, piers, wharves and bridges have been studied by Tirindelli et al. (2003), Cuomo et al. (2007, 2009), Murali et al. (2009), and Meng et al. (2010). All these authors analyzed data from scale model tests to investigate the pressures and loads on beam and deck elements subject to wave impact under various conditions. Wavein- deck loads on fixed offshore structures have been studied by Murray et al. (1997), Finnigan et al. (1997), Bea et al. (1999, 2001), Baarholm et al. (2004, 2009), and Raaij et al. (2007). These authors have studied both simplified and realistic deck structures using a mixture of theoretical analysis and model tests. Other researchers, including Kendon et al. (2010), Schellin et al. (2009), Lande et al. (2011) and Wemmenhove et al. (2011) have demonstrated that various CFD methods can be used to simulate the interaction of extreme waves with both simple and more realistic deck structures, and predict wave-in-deck pressures and loads.

scholarly journals Spatial Patterns and Intensity of the Surface Storm Tracks in CMIP5 Models

2017 ◽  
Vol 30 (13) ◽  
pp. 4965-4981 ◽  
Author(s):  
James F. Booth ◽  
Young-Oh Kwon ◽  
Stanley Ko ◽  
R. Justin Small ◽  
Rym Msadek
Keyword(s):  
Storm Track ◽  
Storm Tracks ◽  
Cmip5 Models ◽  
Western Boundary ◽  
Spatial Correlations ◽  
Boundary Current ◽  
Near Surface ◽  
Surface Stability ◽  
The North ◽  
Basin Scale

To improve the understanding of storm tracks and western boundary current (WBC) interactions, surface storm tracks in 12 CMIP5 models are examined against ERA-Interim. All models capture an equatorward displacement toward the WBCs in the locations of the surface storm tracks’ maxima relative to those at 850 hPa. An estimated storm-track metric is developed to analyze the location of the surface storm track. It shows that the equatorward shift is influenced by both the lower-tropospheric instability and the baroclinicity. Basin-scale spatial correlations between models and ERA-Interim for the storm tracks, near-surface stability, SST gradient, and baroclinicity are calculated to test the ability of the GCMs’ match reanalysis. An intermodel comparison of the spatial correlations suggests that differences (relative to ERA-Interim) in the position of the storm track aloft have the strongest influence on differences in the surface storm-track position. However, in the North Atlantic, biases in the surface storm track north of the Gulf Stream are related to biases in the SST. An analysis of the strength of the storm tracks shows that most models generate a weaker storm track at the surface than 850 hPa, consistent with observations, although some outliers are found. A linear relationship exists among the models between storm-track amplitudes at 500 and 850 hPa, but not between 850 hPa and the surface. In total, the work reveals a dual role in forcing the surface storm track from aloft and from the ocean surface in CMIP5 models, with the atmosphere having the larger relative influence.

scholarly journals On the Relationship between Synoptic Wintertime Atmospheric Variability and Path Shifts in the Gulf Stream and the Kuroshio Extension

2009 ◽  
Vol 22 (12) ◽  
pp. 3177-3192 ◽  
Author(s):  
Terrence M. Joyce ◽  
Young-Oh Kwon ◽  
Lisan Yu
Keyword(s):  
North Atlantic ◽  
North Pacific ◽  
Gulf Stream ◽  
Kuroshio Extension ◽  
Storm Track ◽  
Western Boundary ◽  
Atmospheric Variability ◽  
The North ◽  
The Kuroshio ◽  
The North Pacific

Abstract Coherent, large-scale shifts in the paths of the Gulf Stream (GS) and the Kuroshio Extension (KE) occur on interannual to decadal time scales. Attention has usually been drawn to causes for these shifts in the overlying atmosphere, with some built-in delay of up to a few years resulting from propagation of wind-forced variability within the ocean. However, these shifts in the latitudes of separated western boundary currents can cause substantial changes in SST, which may influence the synoptic atmospheric variability with little or no time delay. Various measures of wintertime atmospheric variability in the synoptic band (2–8 days) are examined using a relatively new dataset for air–sea exchange [Objectively Analyzed Air–Sea Fluxes (OAFlux)] and subsurface temperature indices of the Gulf Stream and Kuroshio path that are insulated from direct air–sea exchange, and therefore are preferable to SST. Significant changes are found in the atmospheric variability following changes in the paths of these currents, sometimes in a local fashion such as meridional shifts in measures of local storm tracks, and sometimes in nonlocal, broad regions coincident with and downstream of the oceanic forcing. Differences between the North Pacific (KE) and North Atlantic (GS) may be partly related to the more zonal orientation of the KE and the stronger SST signals of the GS, but could also be due to differences in mean storm-track characteristics over the North Pacific and North Atlantic.

scholarly journals Storm Track Response to Oceanic Eddies in Idealized Atmospheric Simulations

2018 ◽  
Vol 32 (2) ◽  
pp. 445-463 ◽  
Author(s):  
A. Foussard ◽  
G. Lapeyre ◽  
R. Plougonven
Keyword(s):  
Large Scale ◽  
Heat Budget ◽  
Storm Track ◽  
Convective Heating ◽  
Western Boundary ◽  
Boundary Currents ◽  
Oceanic Fronts ◽  
Budget Analysis ◽  
Poleward Shift ◽  
Oceanic Eddies

ABSTRACT Large-scale oceanic fronts, such as in western boundary currents, have been shown to play an important role in the dynamics of atmospheric storm tracks. Little is known about the influence of mesoscale oceanic eddies on the free troposphere, although their imprint on the atmospheric boundary layer is well documented. The present study investigates the response of the tropospheric storm track to the presence of sea surface temperature (SST) anomalies associated with an eddying ocean. Idealized experiments are carried out in a configuration of a zonally reentrant channel representing the midlatitudes. The SST field is composed of a large-scale zonally symmetric front to which are added mesoscale eddies localized close to the front. Numerical simulations show a robust signal of a poleward shift of the storm track and of the tropospheric eddy-driven jet when oceanic eddies are taken into account. This is accompanied by more intense air–sea fluxes and convective heating above oceanic eddies. Also, a mean heating of the troposphere occurs poleward of the oceanic eddying region, within the storm track. A heat budget analysis shows that it is caused by a stronger diabatic heating within storms associated with more water advected poleward. This additional heating affects the baroclinicity of the flow, which pushes the jet and the storm track poleward.

scholarly journals Loads on a Point-Absorber Wave Energy Converter in Regular and Focused Extreme Wave Events

2020 ◽  
Author(s):  
Eirini Katsidoniotaki ◽  
Edward Ransley ◽  
Scott Brown ◽  
Johannes Palm ◽  
Jens Engström ◽  
...  
Keyword(s):  
Wave Energy ◽  
Wave Train ◽  
Offshore Structures ◽  
Wave Energy Converter ◽  
Extreme Waves ◽  
Extreme Wave ◽  
Energy Converter ◽  
Point Absorber ◽  
Wave Energy Converters ◽  
Extreme Loads

Abstract Accurate modeling and prediction of extreme loads for survivability is of crucial importance if wave energy is to become commercially viable. The fundamental differences in scale and dynamics from traditional offshore structures, as well as the fact that wave energy has not converged around one or a few technologies, implies that it is still an open question how the extreme loads should be modeled. In recent years, several methods to model wave energy converters in extreme waves have been developed, but it is not yet clear how the different methods compare. The purpose of this work is the comparison of two widely used approaches when studying the response of a point-absorber wave energy converter in extreme waves, using the open-source CFD software OpenFOAM. The equivalent design-waves are generated both as equivalent regular waves and as focused waves defined using NewWave theory. Our results show that the different extreme wave modeling methods produce different dynamics and extreme forces acting on the system. It is concluded that for the investigation of point-absorber response in extreme wave conditions, the wave train dynamics and the motion history of the buoy are of high importance for the resulting buoy response and mooring forces.

scholarly journals Mean Dynamic Topography of the Ocean Derived from Satellite and Drifting Buoy Data Using Three Different Techniques*

2009 ◽  
Vol 26 (9) ◽  
pp. 1910-1919 ◽  
Author(s):  
Nikolai Maximenko ◽  
Peter Niiler ◽  
Luca Centurioni ◽  
Marie-Helene Rio ◽  
Oleg Melnichenko ◽  
...  
Keyword(s):  
Ocean Surface ◽  
Horizontal Resolution ◽  
Global Ocean ◽  
Momentum Balance ◽  
Small Scale ◽  
Western Boundary ◽  
Dynamic Topography ◽  
Geoid Model ◽  
Near Surface ◽  
Mean Dynamic Topography

Abstract Presented here are three mean dynamic topography maps derived with different methodologies. The first method combines sea level observed by the high-accuracy satellite radar altimetry with the geoid model of the Gravity Recovery and Climate Experiment (GRACE), which has recently measured the earth’s gravity with unprecedented spatial resolution and accuracy. The second one synthesizes near-surface velocities from a network of ocean drifters, hydrographic profiles, and ocean winds sorted according to the horizontal scales. In the third method, these global datasets are used in the context of the ocean surface momentum balance. The second and third methods are used to improve accuracy of the dynamic topography on fine space scales poorly resolved in the first method. When they are used to compute a multiyear time-mean global ocean surface circulation on a 0.5° horizontal resolution, both contain very similar, new small-scale midocean current patterns. In particular, extensions of western boundary currents appear narrow and strong despite temporal variability and exhibit persistent meanders and multiple branching. Also, the locations of the velocity concentrations in the Antarctic Circumpolar Current become well defined. Ageostrophic velocities reveal convergent zones in each subtropical basin. These maps present a new context in which to view the continued ocean monitoring with in situ instruments and satellites.

scholarly journals SIKLON TROPIS, KARASTERISTIK DAN PENGARUHNYA DI WILAYAH INDONESIA PADA TAHUN 2012

2015 ◽  
Vol 16 (2) ◽  
pp. 61
Author(s):  
M. Djazim Syaifullah
Keyword(s):  
Life Cycle ◽  
Tropical Cyclone ◽  
Tropical Cyclones ◽  
Hot Spot ◽  
Weather Conditions ◽  
Mature Stage ◽  
Severe Drought ◽  
Wet Season ◽  
Human Effort ◽  
The Moment

Tulisan ini adalah sebuah dan analisis karasteristik dari siklon tropis termasuk proses siklus hidupnya, struktur, skala kekuatan dan bagaimana pengaruhnya di daerah Indonesia. Analisis siklon tropis dikhususkan untuk kejadian-kejadian di daerah Pasifik Barat dan Laut Cina Selatan. Salah satu pengaruh siklon tropis adalah munculnya hotspot di Sumatera dan Kalimantan. Siklon tropis adalah sebuah yang fenomena meteorologi yang dengan potensi besar dampak di area kerusakan yang dilaluinya. Siklon tropis mempunyai kekuatan yang sangat besar dan tidak ada usaha manusia yang dapat mencegah atau menghilangkan siklon tropis. Siklon Tropis mempunyai siklus mulai sejak saat pembentukannya sampai kepunahannya. Ada tiga tahap : tahap pembentukan, tahap matang dan tahap pelemahan. Indonesia secara umum mendapatkan pengaruh secara tidak langsung dari keberadaan siklon tropis ini, dimana pada musim kering ini akan memperparah bencana kekeringan di beberapa daerah di Indonesia khususnya di wilayah Kalimantan dan Sumatera.Kata Kunci: siklon tropis, kebakaran hutan, hotspotThis paper is an overview and analisys of tropical cyclone charasteristics consit of their life cycle processes, structures, scale of strength and how its influence in Indonesian region. Tropical cyclone analysis is devoted to the events in the Western Pacific region and the South China Sea. Observed influence of tropical cyclones is the emergence of hot spots in Sumatera and Kalimantan as well as it happened rains in some areas. The tropical cyclone is a meteorological phenomenon with huge potential impact on the area of damage in its path. Tropical cyclone strength was so big and there was no human effort that can prevent or eliminate a tropical cyclone. Tropical cyclones have a life cycle starting from the moment of its formation until its extinction. There are three stages : formation stage, mature stage and attenuation stage. Indonesia generally received indirect impact on changing weather conditions. In the dry season will increase the incidence of tropical cyclone severe drought level in the region of Indonesia, particularly Sumatera and Kalimantan and result in the emergence of the number of fires (hot spot) which is quite a lot. In the wet season tropical cyclone events can cause increased rainfall causes floods, especially in areas close to the location of the cyclone, for example in the area of the northern part of Kalimantan and Sulawesi.Keywords : tropical cyclone, forest fire, hotspot

Sign in / Sign up

Export Citation Format

Share Document