Shorelines_Oct2012_Sept2014: Hurricane Sandy Beach Response and Recovery at Fire Island, New York: Shoreline and Beach Profile Data, October 2012 to October 2014.

MHW Shoreline interpolation from tabular DGPS Data (October 28 2012-Dec 2013)
Continuous alongshore DGPS data were collected to assess the positional changes of the MHW shoreline and the upper portion of the beach. Data were collected along shore-parallel tracks to capture the base of the dune, the mid-beach, and the upper and lower foreshore. For each survey date, ASCII point data was imported into Matlab (v R2012a) and processed as follows:
For surveys October 28 2012-Dec 2013 the MHW shoreline (0.46 m North American Vertical Datum of 1988 [NAVD 88]; Weber and others, 2005) is derived from the field data by using an interpolation method that creates a series of equally-spaced cross-shore profiles between the two survey lines that flank the MHW contour. The foreshore slope is assumed to be uniform on each profile. Using this slope and the two surveyed positions on each cross-shore profile, a simple geometric calculation is done to find where each profile line intersects the MHW contour. At this interesection a point is generated, and the series of points making up the MHW shoreline are appended to create a polyline shoreline.
The resulting ployline shapefile (for each method) was named FIIS_shoreline_DATE, where date is the date of the field survey. For example: MHW extracted polyline for October 28 2012 would be named FIIS_shoreline_2012Oct28.shp

MHW Shoreline interpolation from tabular DGPS Data (Jan 2014 - Sept 2014)
Continuous alongshore DGPS data were collected to assess the positional changes of the MHW shoreline and the upper portion of the beach. Data were collected along shore-parallel tracks to capture the base of the dune, the mid-beach, and the upper and lower foreshore. For each survey date, ASCII point data was imported into Matlab (v R2012a) and processed as follows:
For surveys January 2014 and beyond, a new, survey approach was implemented that was designed to improve surface interpolation by collecting a more dense network xyz points along the beach face. For these surveys, alongshore transects are collected at the berm crest, low water mark and mid-beach face. In addition, a sinusoidal transect is collected by driving from the water's edge to the top of the berm crest at approximately 45 degrees to the orientation of the shoreline. The xyz data are used to create an interpolated surface from which the MHW contour is extracted.
The resulting ployline shapefile (for each method) was named FIIS_shoreline_DATE, where date is the date of the field survey. For example: MHW extracted polyline for October 28 2012 would be named FIIS_shoreline_2012Oct28.shp

The shoreline file FIIS_Shorlines_DATE was coded with attribute fields: ID, DATE_, and UNCERT (Uncertainty). These fields are required for the Digital Shoreline Analysis System (DSAS), which was used to calculate shoreline change rates. Additional fields: Agency, Proxy, Data_Source, Notes_, and Originator_, were added to comply with the existing historical shoreline shapefile database for Fire Island. Agency refers to the contact organization (ex: USGS, NPS), Proxy is the shoreline proxy used to derive the shoreline (ex: MHW, HWL), Data_Source is the material or source of the shoreline data (ex: lidar, air photos, GPS), Notes_ indicates the extent of the shoreline data along Fire Island, and the Originator_ attribute is the contact organization and contact person responsible for the generation of the shoreline.

Calculation of shoreline uncertainty: In order to determine the uncertainties associated with individual shorelines, a methodology following Morton and Miller (2005) and Hapke and others, (2006) was used to estimate a positional error value for each shoreline. The shoreline position uncertainty is estimated using a square root of the sum of the squares of multiple terms. Total shoreline positional error is a function of the errors inherent in the source data/data collection, and those errors generated in the creation and identification of the vector shoreline.
Oct 2012–Dec 2013 The terms used for the interpolated shorelines derived from October 2012 to December 2013 were: 1) predicted MHW uncertainty - an estimate of interpolated shoreline position accuracy based on the slope, and distance between track lines (1 - 2.5 m); 2) average measured MHW error - the positional difference between the interpolated MHW shoreline and the location of the MHW elevation on the cross-shore profiles from the same survey date (1 - 7.5 m); 3) collection and equipment error - derived from static portions of each survey (0.07 - 0.12 m); 4) A term to account for horizontal positional variation found when driving the GPS (horizontal to the Polaris) on a sloped surface (0.02 - 0.1 m). Individual shoreline uncertainties are found in the shapefile [ACCURACY] attribute and in the metadata file.
Jan 2014–Sept 2014 For surveys January 2014 and September 2014 the MHW elevation was extracted from a surface generated from field collected data points. The terms used to estimate error for the extracted shorelines were: 1) average measured MHW - the positional difference between the interpolated MHW shoreline and the location of the MHW elevation on the cross-shore profiles from the same survey date (2.2-3.2 m; Sept 2014 used an average of previous time periods, as a large displacement of MHW due to high waves occurred in the day between shoreline and profile surveys); 2) collection and equipment error - derived from static portions of each survey (0.07 - 0.1 m); and 3) uncertainty of the interpolated surface estimated by withholding 10% of the original data points and calculating an root mean square error (RMSE) of the difference between the withheld points and the surface (0.04 – 0.06 m). Individual shoreline uncertainties are found in the shapefile [ACCURACY] attribute and in the metadata file.

The shoreline file's updated uncertainty rates were imported into a personal geodatabase in ArcCatalog (v.10.0) for use with the Digital Shoreline Analysis System (DSAS v.4.0) software to perform rate calculations.

All shorelines were appended into one feature class (in a personal geodatabase). ArcToolbox>>Data Management Tools>>General>>Append: select each FIIS_shoreline_DATE. Shorelines for the following dates were appended: Oct 28 2012, Nov 01/02 2012, Dec 01 2012, Dec 12/13 2012, Jan 10 2013, Feb 14 2013, Mar 13 2013, Apr 10 2013, June 24 2013, Sept 19 2013, Dec 04 2013, Jan 30 2014 and Sept 08 2014.

Keywords section of metadata optimized for discovery in USGS Coastal and Marine Geology Data Catalog.

Added keywords section with USGS persistent identifier as theme keyword.