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Cos Cob, CT, United States

Bacopoulos P.,University of Central Florida | Dally W.R.,Surfbreak Engineering science Inc. | Hagen S.C.,University of Central Florida | Cox A.T.,Oceanweather Inc.
Coastal Engineering

A novel set of measurements of winds, water levels, and currents recorded in September of 2004 captured the landfall of Hurricane Jeanne. The dataset provides a full picture of the meteorology and hydrodynamics associated with Hurricane Jeanne and are used to test the state-of-the-art in numerical modeling of storm surge. A shallow water equations model (ADCIRC) is driven by rigorously modeled winds and astronomic tides to replicate continuous hydrodynamic records at two stations, one in Melbourne Beach (Spessard) and the other inside Port Canaveral (Trident Pier), where instrumentation was located by happenstance. Simulation results represent the time-series of water surface elevations measured in the open coast off Melbourne Beach (Spessard) within 0.05. m root mean square error and within 12% of observed maximum surge elevation (1.35. m simulated vs. 1.52. m measured) and exhibit details induced by a 'loop' performed by the hurricane before it made landfall. Prediction of water levels inside Port Canaveral (Trident Pier) is to within 0.06. m root mean square error and includes the observed forerunner and peak surge of the hurricane. In regard to nearshore currents off Melbourne Beach (Spessard), the timing of a sudden switch in the direction of the measured (longshore) current is replicated well with the magnitude of the peak current simulated to within 14% of observation (0.96. m/s modeled vs. 1.11. m/s measured). The capability to accurately simulate the tidal and storm surge hydrodynamics during Hurricane Jeanne provides confidence in using this class of shallow water equations models in coastal engineering practice. © 2011 Elsevier B.V. Source

Bacopoulos P.,University of Central Florida | Hagen S.C.,University of Central Florida | Cox A.T.,Oceanweather Inc. | Dally W.R.,Surfbreak Engineering science Inc. | Bratos S.M.,U.S. Army
Journal of Hydrology

Water surface elevations and daily flows are measured in the St. Johns and Nassau Rivers (north Florida) and reveal a storm event in mid-May 2009 and a sea level anomaly in June and July 2009. In an effort to reproduce these events, wind and tidally driven hydrodynamics are simulated from the deep ocean into the St. Johns and Nassau Rivers using a shallow water equations model. Calibration adjusts spatially distributed Manning's roughness based on modeled-observed discharge. For validation, the model captures the regular tidal fluctuation as well as the hydrodynamic responses of the storm event in mid-May at the six water level gaging stations. At the flow gaging station, the model captures the ebb tendency of the tide as well as a strong perturbation (flood pulse) that occurs because of the storm event in mid-May. © 2011 Elsevier B.V. Source

Wang X.L.,Environment Canada | Feng Y.,Environment Canada | Swail V.R.,Environment Canada | Cox A.,Oceanweather Inc.
Journal of Climate

This study characterizes historical changes in surface wind speed and ocean surface waves in the Beaufort- Chukchi-Bering Seas using Environment Canada's Beaufort Wind and Wave Reanalysis for the period 1970-2013. The results show that both the significant wave height (Hs) and mean wave period (Tm) have increased significantly over the Bering Sea in July and August and over the Canadian Beaufort Sea westward to the northern Bering Sea in September, and that the 1992-2013 trends in September mean Hs agree well with satellite-based trend estimates for 1993-2010. Most outstandingly, the regional mean Tm has increased at a rate of 3%-4% yr-1 of the corresponding 1970-99 climatology; it has more than tripled since 1970. Also, the regional mean Hs has increased at a rate of 0.3% to 0.8% yr-1. The trends of lengthening wave period and increasing wave height imply a trend of increasing wave energy flux, providing a mechanism to break up sea ice and accelerate ice retreat. The results also show that changes in the local wind speeds alone cannot explain the significant changes in waves. The wind speeds show significant increases over the Bering Sea to the north of Alaska in July and over the central part of the domain in August and September, with decreases in the region off the Canadian coasts in August. In the region west of the Canadian coast, the climatological mean wind direction has rotated clockwise in July and August, with the climatological anticyclonic center being displaced northeastward in August. © 2015 American Meteorological Society. Source

Kennedy A.B.,University of Notre Dame | Gravois U.,University of Florida | Zachry B.C.,Texas Tech University | Zachry B.C.,National Oceanic and Atmospheric Administration | And 8 more authors.
Geophysical Research Letters

A large, unpredicted, water level increase appeared along a substantial section of the western Louisiana and northern Texas (LATEX) coasts 12-24 hrs in advance of the landfall of Hurricane Ike (2008), with water levels in some areas reaching 3 m above mean sea level. During this time the cyclonic wind field was largely shore parallel throughout the region. A similar early water level rise was reported for both the 1900 and the 1915 Galveston Hurricanes. The Ike forerunner anomaly occurred over a much larger area and prior to the primary coastal surge which was driven by onshore directed winds to the right of the storm track. We diagnose the forerunner surge as being generated by Ekman setup on the wide and shallow LATEX shelf. The longer forerunner time scale additionally served to increase water levels significantly in narrow-entranced coastal bays. The forerunner surge generated a freely propagating continental shelf wave with greater than 1.4 m peak elevation that travelled coherently along the coast to Southern Texas, and was 300 km in advance of the storm track at the time of landfall. This was, at some locations, the largest water level increase seen throughout the storm, and appears to be the largest freely-propagating shelf wave ever reported. Ekman setup-driven forerunners will be most significant on wide, shallow shelves subject to large wind fields, and need to be considered for planning and forecasting in these cases. Copyright 2011 by the American Geophysical Union. Source

Cardone V.J.,Oceanweather Inc. | Callahan B.T.,Oceanweather Inc. | Cox A.T.,Oceanweather Inc. | Morrone M.A.,Oceanweather Inc. | Swail V.R.,Environment Canada
International Journal of Climatology

The impact of extreme sea states on offshore infrastructure is of intense interest in the ocean engineering community at the present time. In this study, a new quality-controlled database of global satellite-derived estimates of significant wave height (HS) and surface marine wind speed from seven missions spanning the period August 1991-March 2010, known as GlobWave, is scanned to yield over 5000 ocean basin specific orbit segments with peak HS > 12 m. This population was subsequently distilled to a population of 120 individual storms [so-called very extreme sea states (VESS) storms], in which there was at least one altimeter estimate of HS > 16 m. The highest HSs were observed in the Northern Hemisphere with ten orbit segments in the North Atlantic Ocean (NAO) with a peak HS of >18 m followed by four segments in the North Pacific Ocean (NPO). Only three HS peaks >18 m were seen in the entire Southern Oceans. Three of the >5000 orbit segments had a peak HS >20 m with the highest at 20.6 m. The number of VESS storms detected is greatest in the NAO (the smallest basin), a result that appears to be consistent with general circulation studies of extratropical cyclogenesis frequency and intensity in general atmospheric circulation models. A new continuous 33-year global wave hindcast (GROW2012) based on a new atmospheric reanalysis wind field product appears to provide unbiased estimates of the probability of exceedance of VESS in extratropical storms and small-basin dependent biases (0.5-1.5 m) of peak HS greater than ~16 m. GROW2012 was, therefore, applied with a voyage simulator for nine trade routes to assess the risk of a merchant vessel that does not avail itself of weather routing of encountering VESS. The highest monthly exceedance probabilities (MEPs) at the VESS threshold of 14 m are found in the NAO and NPO at ~0.1% during winter months. The alternative statistical distribution of the MEP of the single maximum peak sea state to be expected for a voyage for any month (MEPm) shows that the highest MEPm is for the month of December in the NAO along the great circle route between the middle US East Coast and entrance to English Channel and in the NPO along the Yokohama-Seattle route, at about 3%. Still, the overall probability of a vessel encountering sea states that may contain waves capable of catastrophic damage over a 33-year lifetime is quite small with mean number of hours of exposure to a vessel typically less than ~3 h for six of the nine routes and a maximum of 10 h for two of the routes. © 2014 Royal Meteorological Society. Source

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