USGS CoastCam at Isla Verde, Puerto Rico: 2018-2019 GNSS Topography Survey Data

ACQUISITION The GNSS ground survey was conducted using a Trimble R10 survey-grade dual-frequency GNSS receiver set to record raw GNSS observables in Post-Processed Kinematic (PPK) mode. Topographic measurements of the ground surface were made using the GNSS receiver mounted on a backpack and set to collect continuous observations at a rate of 1 hertz (Hz) while the surveyor walked on the ground surface. These data acquisition steps are similar to those reported in Brown and others (2018), the difference being the GNSS recording interval and the GNSS survey equipment model.

GNSS POST-PROCESSING After the survey, concurrent GNSS observations were downloaded from the National Geodetic Survey (NGS) Continuously Operating Base Station (CORS), ZSU4, located approximately 2.5 kilometers from the study area. These data were then used to post-process the GNSS measurements using the Trimble Business Center ver. 5.00 software package. The final, differentially-corrected, precise GNSS antenna positions were exported in American Standard Code for Information Interchange (ASCII) text format, with projected horizontal coordinates into the North American datum of 1983 (National Spatial Reference System 2011) Universal Transverse Mercator Zone 20 North(NAD 83 (2011), UTM Zone 20N), and vertical coordinates into the Puerto Rico Vertical Datum of 2002 (PRVD02), GEOID12B. These post-processing steps are similar to those reported in Brown and others (2018). Ground elevations were determined by subtracting the GNSS antenna height above the ground. The final beach profile data were written to a text file (.xyz) in tabular format, with columns representing: 1) Easting (NAD83, UTM Zone 20N), 2) Northing (NAD83, UTM Zone 20N), and 3) Orthometric Elevation (PRVD02, GEOID12B).