The ADCIRC model is a high-performance, cross-platform numerical ocean circulation model popular in simulating storm surge, tides, and coastal circulation problems. [1] [2] [3] [4] Originally developed by Drs. Rick Luettich and Joannes Westerink, [5] [6] the model is developed and maintained by a combination of academic, governmental, and corporate partners, including the University of North Carolina at Chapel Hill, the University of Notre Dame, and the US Army Corps of Engineers. [7] The ADCIRC system includes an independent multi-algorithmic wind forecast model and also has advanced coupling capabilities, allowing it to integrate effects from sediment transport, ice, waves, surface runoff, and baroclinicity.
The model is free, with source code made available by request via the website, [1] allowing users to run the model on any system with a Fortran compiler. A pre-compiled Windows version of the model can also be purchased alongside the SMS software. [8] ADCIRC is coded in Fortran, and can be used with native binary, text, or netCDF file formats.
The model formulation [9] is based on the shallow water equations, solving the continuity equation (represented in the form of the Generalized Wave Continuity Equation [10] ) and the momentum equations (with advective, Coriolis, eddy viscosity, and surface stress terms included). ADCIRC utilizes the finite element method in either three-dimensional or two-dimensional depth-integrated form on a triangular unstructured grid with Cartesian or spherical coordinates. It can run in either barotropic or baroclinic modes, allowing inclusion of changes in water density and properties such as salinity and temperature. ADCIRC can be run either in serial mode (e.g. on a personal computer) or in parallel on supercomputers via MPI. The model has been optimized to be highly parallelized, in order to facilitate rapid computation of large, complex problems. [11] [12]
ADCIRC is able to apply several different bottom friction formulations including Manning's n-based bottom drag due to changes in land coverage (such as forests, cities, and seafloor composition), as well as utilize atmospheric forcing data (wind stress and atmospheric pressure) from several sources, and further reduce the strength of the wind forcing due to surface roughness effects. [13] [14] The model is also able to incorporate effects such as time-varying topography and bathymetry, boundary fluxes from rivers or other sources, tidal potential, and sub-grid scale features like levees.
ADCIRC is frequently coupled to a wind wave model such as STWAVE, SWAN, or WAVEWATCH III, especially in storm surge applications where wave radiation stress can have important effects on ocean circulation and vice versa. In these applications, the model is able to take advantage of tight coupling with wave models to increase calculation accuracy. [14] [15]
The 1938 New England Hurricane was one of the deadliest and most destructive tropical cyclones to strike the United States. The storm formed near the coast of Africa on September 9, becoming a Category 5 hurricane on the Saffir–Simpson hurricane scale, before making landfall as a Category 3 hurricane on Long Island on Wednesday, September 21. It is estimated that the hurricane killed 682 people, damaged or destroyed more than 57,000 homes, and caused property losses estimated at $306 million. Multiple other sources, however, mention that the 1938 hurricane might have really been a more powerful Category 4, having winds similar to Hurricanes Hugo, Harvey, Frederic and Gracie when it ran through Long Island and New England. Also, numerous others estimate the real damage between $347 million and almost $410 million. Damaged trees and buildings were still seen in the affected areas as late as 1951. It remains the most powerful and deadliest hurricane in recorded New England history, perhaps eclipsed in landfall intensity only by the Great Colonial Hurricane of 1635.
A storm surge, storm flood, tidal surge, or storm tide is a coastal flood or tsunami-like phenomenon of rising water commonly associated with low-pressure weather systems, such as cyclones. It is measured as the rise in water level above the normal tidal level, and does not include waves.
Hurricane Fabian was a powerful Cape Verde hurricane that impacted Bermuda in early September during the 2003 Atlantic hurricane season. It was the sixth named storm, fourth hurricane, and first major hurricane of the season, developed from a tropical wave in the tropical Atlantic Ocean on August 25. It moved west-northwestward under the influence of the subtropical ridge to its north, and steadily strengthened in an area of warm sea surface temperatures and light wind shear. The hurricane attained a peak intensity of 145 mph (233 km/h) on September 1, and it slowly weakened as it turned northward. On September 5, Fabian made a direct hit on Bermuda with wind speeds of over 120 mph (190 km/h). After passing the island, the hurricane turned to the northeast, and became extratropical on September 8, before dissipating two days later.
Hurricane Gloria was a powerful hurricane that caused significant damage along the east coast of the United States and in Atlantic Canada during the 1985 Atlantic hurricane season. It was the first significant tropical cyclone to strike the northeastern United States since Hurricane Agnes in 1972 and the first major storm to affect New York City and Long Island directly since Hurricane Donna in 1960. Gloria was a Cape Verde hurricane originating from a tropical wave on September 16 in the eastern Atlantic Ocean. After remaining a weak tropical cyclone for several days, Gloria intensified into a hurricane on September 22 north of the Lesser Antilles. During that time, the storm had moved generally westward, although it turned to the northwest due to a weakening of the ridge. Gloria quickly intensified on September 24, and the next day reached peak winds of 145 mph (233 km/h). The hurricane weakened before striking the Outer Banks of North Carolina on September 27. Later that day, Gloria made two subsequent landfalls on Long Island and across the coastline of western Connecticut, before becoming extratropical on September 28 over New England. The remnants moved through Atlantic Canada and went on to impact Western Europe, eventually dissipating on October 4.
Hurricane Ione was a strong, Category 4 hurricane that affected the U.S. state of North Carolina in September 1955, bringing high winds and significant rainfall. It came on the heels of Hurricanes Connie and Diane, and compounded problems already caused by the two earlier hurricanes. Spawned by a tropical wave which left the African coast on September 6, the system became a tropical depression in the tropical North Atlantic, before turning northwest and developing into a hurricane. After turning back to the west east of the Bahamas, Ione turned northwest and northward, moving across eastern North Carolina before moving east-northeastward out to sea. Ione caused $600 million (2005 USD) in damage, much of it to crops across North Carolina. As a result of Ione's impacts seven people died.
Numerical weather prediction (NWP) uses mathematical models of the atmosphere and oceans to predict the weather based on current weather conditions. Though first attempted in the 1920s, it was not until the advent of computer simulation in the 1950s that numerical weather predictions produced realistic results. A number of global and regional forecast models are run in different countries worldwide, using current weather observations relayed from radiosondes, weather satellites and other observing systems as inputs.
The Great Colonial Hurricane of 1635 brushed Virginia and then passed over southeastern New England in August. Accounts of the storm are very limited, but it was likely the most intense hurricane to hit New England since European colonization.
A tropical cyclone forecast model is a computer program that uses meteorological data to forecast aspects of the future state of tropical cyclones. There are three types of models: statistical, dynamical, or combined statistical-dynamic. Dynamical models utilize powerful supercomputers with sophisticated mathematical modeling software and meteorological data to calculate future weather conditions. Statistical models forecast the evolution of a tropical cyclone in a simpler manner, by extrapolating from historical datasets, and thus can be run quickly on platforms such as personal computers. Statistical-dynamical models use aspects of both types of forecasting. Four primary types of forecasts exist for tropical cyclones: track, intensity, storm surge, and rainfall. Dynamical models were not developed until the 1970s and the 1980s, with earlier efforts focused on the storm surge problem.
Renaissance Computing Institute (RENCI) was launched in 2004 as a collaboration involving the State of North Carolina, University of North Carolina at Chapel Hill (UNC-CH), Duke University, and North Carolina State University. RENCI is organizationally structured as a research institute within UNC-CH, and its main campus is located in Chapel Hill, NC, a few miles from the UNC-CH campus. RENCI has engagement centers at UNC-CH, Duke University (Durham), and North Carolina State University (Raleigh).
In fluid dynamics, wind wave modeling describes the effort to depict the sea state and predict the evolution of the energy of wind waves using numerical techniques. These simulations consider atmospheric wind forcing, nonlinear wave interactions, and frictional dissipation, and they output statistics describing wave heights, periods, and propagation directions for regional seas or global oceans. Such wave hindcasts and wave forecasts are extremely important for commercial interests on the high seas. For example, the shipping industry requires guidance for operational planning and tactical seakeeping purposes.
The history of numerical weather prediction considers how current weather conditions as input into mathematical models of the atmosphere and oceans to predict the weather and future sea state has changed over the years. Though first attempted manually in the 1920s, it was not until the advent of the computer and computer simulation that computation time was reduced to less than the forecast period itself. ENIAC was used to create the first forecasts via computer in 1950, and over the years more powerful computers have been used to increase the size of initial datasets and use more complicated versions of the equations of motion. The development of global forecasting models led to the first climate models. The development of limited area (regional) models facilitated advances in forecasting the tracks of tropical cyclone as well as air quality in the 1970s and 1980s.
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The following is a glossary of tropical cyclone terms.
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