Extratropical Storm March 2018 Assessment of Potential Coastal Change Impacts: 0800 AM EST FRI MAR 02 2018

For dune morphology data: Elevation data from lidar surveys were interpolated in MATLAB (version 2017a) to a gridded domain that was rotated parallel to the shoreline and had a resolution of 10 m in the longshore direction and 2.5 m in the cross-shore direction. The interpolation method applied spatial filtering with a Hanning window that was twice as wide as the grid resolution. Dune morphology data were extracted from the elevation grid in MATLAB. Dune morphology data were then summarized to 1 km sections. Sections with greater than 75 percent of data missing were flagged with the invalid number of -999. The 1-km smoothed dune crest (DHIGH), toe (DLOW) and root mean square (RMS) error for each (DHIrms and DLOrms) were written to line shapefiles using MATLAB's shapewrite.m script.

For hydrodynamic data: Water level was computed in MATLAB by adding storm surge from NOAA’s Probabilistic Tropical Storm Surge (P- Surge) model (https://slosh.nws.noaa.gov/psurge2.0/) to wave setup and runup. The wave height and period used for calculating wave runup and setup came from the Wavewatch III model. Hydrodynamic parameters were calculated in MATLAB and exported into ArcGIS shapefile format. For details on modeling parameterization, see: Stockdon, H.F., Doran, K.J., Thompson, D.M., Sopkin, K.L., Plant, N.G., and Sallenger, A.H., 2012, National assessment of hurricane-induced coastal erosion hazards: Gulf of Mexico: U.S. Geological Survey Open-File Report 2012-1084, 51 p. https://pubs.usgs.gov/of/2012/1084/

Probabilities of coastal erosion hazards were based on estimating the likelihood that the beach system would experience erosion and deposition patterns consistent with collision (PCOL), overwash (POVW), or inundation (PIND) regimes. The regimes were calculated by using values of dune morphology and mean and extreme water levels for each 1 km section, such that the probability of collision (PCOL) occurs when extreme water levels reach the dune toe; overwash (POVW) when extreme water levels reach the dune crest; and inundation (PIND) when mean water levels reach the dune crest. Probabilities were calculated in MATLAB and exported using MATLAB's shapewrite.m script. For details on modeling parameterization, see: Stockdon, H.F., Doran, K.J., Thompson, D.M., Sopkin, K.L., Plant, N.G., and Sallenger, A.H., 2012, National assessment of hurricane-induced coastal erosion hazards: Gulf of Mexico: U.S. Geological Survey Open-File Report 2012-1084, 51 p. https://pubs.usgs.gov/of/2012/1084/

Added keywords section with USGS persistent identifier as theme keyword.

Version 2.0: This previously published metadata record was updated as part of the version 2.0 revision, after it was identified that the DHIrms and DLOrms fields mistakenly defined the root mean squared error unit in square meters, instead of meters. This did not impact the data values reported in the shapefiles.