Estimation of extreme sea levels over the eastern continental shelf of North America



[1] This study presents distributions of extreme sea levels over the eastern continental shelf of North America (ECSNA) associated with storm surges and tidal surface elevations produced by a 2-D ocean circulation model for the period 1979–2010. The 2-D circulation model is driven by atmospheric and tidal forcing. The large-scale atmospheric forcing is the wind stress and sea level atmospheric pressures extracted from NCEP (National Centers for Environmental Prediction) Climate Forecast System Reanalysis (CFSR) fields at 6 h intervals. A parameterized vortex is inserted into the CFSR fields to better represent the atmospheric forcing associated with a tropical storm or hurricane. The tidal forcing includes specification of tides at model open boundaries and tide generating potential at each model grid. The model performance is assessed using observed sea levels over the ECSNA. The simulated surface elevations driven by the atmospheric force are used to estimate the 50 year return level of extreme sea levels associated with storm surges over the ECSNA using an extremal analysis. The potential regions of the ECSNA to be threatened by severe storm surges are presented. The extreme total sea levels due to tides and storm surges are also estimated using the Monte Carlo method from model results. Regions over the ECSNA experiencing severe 50 year extreme total sea levels due to the storm surges and tides are similar to those regions of 50 year extreme surge-induced elevations, but with much higher extreme values.