Simulation of Storm Surge in Northeast Coast of the US; a Closer Look at the Wind Forcing

Torres, Marissa J. (University of Rhode Island) | Hashemi, M. Reza (University of Rhode Island) | Hayward, Scott (University of Rhode Island) | Ginis, Isaac (University of Rhode Island) | Spaulding, Malcolm (University of Rhode Island)

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ABSTRACT

A coupled ADCIRC+SWAN model was forced with parametric and global wind products from NHC and ECMWF databases, respectively, to simulate and examine the storm surge responses of Hurricanes Bob (1991) and Irene (2011) in Rhode Island coastal waters. Comparisons with NOAA, USGS, and USACE observation/hindcast data showed that the location of the hurricane track in relation to the study area is paramount when determining which wind product should be used in storm surge simulations. Parametric winds better predict storm surge at locations within the RMW, where global winds lack horizontal resolution, and vice versa for locations outside the RMW.

INTRODUCTION

New England is not a frequent location for land-falling hurricanes, though it has weathered its share of storms over the past several decades. Tropical cyclones developing in the south-western Atlantic typically travel northward along the East Coast and swirl out into the Atlantic without reaching New England. However, the storms that have made landfall in New England since the 1900s have caused moderate to severe damage. The most notable of which was the Great Hurricane of 1938 that came without warning and produced in excess of 4 meters of storm surge in some areas, and recent Hurricane Sandy in 2012 which led to major economic loss in this region.

Climate scientists have been studying the frequency and intensity of hurricanes over time and space, and have developed global and regional climate models to better predict the characteristics of future hurricanes. In parallel, similar efforts have been made, by ocean scientists/engineers, to predict storm surge and waves generated by these storms. The primary model used by the National Weather Service for predicting storm surge due to hurricanes is the Sea, Lake, and Overland Surges from Hurricanes (SLOSH) model. A popular tool for numerical simulation of storm surge is the ADvanced CIRCulation (ADCIRC) model, which provides the solution over a flexible, unstructured computational domain. In terms of waves which are generated during hurricanes, Simulating WAves Nearshore (SWAN) is a popular spectral wave model that solves the spectral action balance equation, and is coupled with ADCIRC for use in this study. With regard to wind forcing of tropical storms, ADCIRC has a range of options, including the Holland parametric wind model (Holland, 1980) to compute wind velocities at each node, and using wind field data (wind velocity and surface pressure) over a regular grid, where ADCIRC will interpolate this forcing over the domain.