Coastal Topography—Long Island, New York, Post-Hurricane Irene, 30 August 2011

Woolpert, Inc. reports that 15 flight lines of high density data, at a nominal pulse spacing (NPS) of 1.0 meter, was collected over 120 kilometers of coastline (1 km swath width) along the southern shore of Long Island, New York using a Leica ALS50-II lidar sensor. Multiple returns were recorded for each laser pulse along with an intensity value for each return. A total of one (1) mission was flown on August 30, 2011. A minimum of one airborne global positioning system (GPS) base station was used in support of the LiDAR data acquisition. 11 ground control points were surveyed through static methods. The geoid used to reduce satellite derived elevations to orthometric heights was Geoid09. All data for the task order is referenced to UTM 18N, NAD83, NAVD88, in meters. Airborne GPS data was differentially processed and integrated with the post processed IMU data to derive a smoothed best estimate of trajectory (SBET). The SBET was used to reduce the LiDAR slant range measurements to a raw reflective surface for each flight line. The coverage was classified to extract a bare earth digital elevation model (DEM) and separate last returns. In addition to the LAS deliverables, one layer of coverage were delivered in the ArcINFO ArcGrid binary format: bare-earth. System Parameters: - Type of Scanner = LH Systems ALS50 - Data Acquisition Height = 1,981 meters (6,500 feet) AGL - Scanner Field of View = 40 degrees - Scan Frequency = 41.8 Hertz - Pulse Repetition Rate - 115.6 Kilohertz - Aircraft Speed = 130 Knots - Swath Width = 1,442 meters (4,732 feet) - Number of Returns Per Pulse = Maximum of 4 - Distance Between Flight Lines = 1,010 meters (3,313 feet). The individual flight lines were inspected to ensure the systematic and residual errors have been identified and removed. Then, the flight lines were compared to adjacent flight lines for any mismatches to obtain a homogenous coverage throughout the project area. The point cloud underwent a classification process to determine bare-earth points and non-ground points utilizing "first and only" as well as "last of many" LiDAR returns. This process determined bare-earth points (Class 2), Noise (Class 7), and unclassified data (Class 1). The bare-earth (Class 2 - Ground) LiDAR points underwent a manual QA/QC step to verify that artifacts have been removed from the bare-earth surface. The surveyed ground control points are used to perform the accuracy checks and statistical analysis of the LiDAR dataset.

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.