1996-2000 NOAA/USGS/NASA Airborne LiDAR Assessment of Coastal Erosion (ALACE) Project
for the US Coastline
This data set includes data collected from 1996-2000 and covers the states of AL,FL,LA,MS,DE,MD,VA,CT,MA,ME,NH,
NJ,NY,RI,NC,SC,GA,CA OR,WA,TX OH,PA. Laser beach mapping uses a pulsed laser ranging
system mounted onboard an aircraft to measure ground elevation and coastal topography.
The laser emits laser beams at high frequency and is directed downward at the earth's
surface through a port opening in the bottom of the aircraft's fuselage. The laser
system records the time difference between emission of the laser beam and the reception
of the reflected laser signal in the aircraft. The aircraft travels over the beach
at approximately 60 meters per second while surveying from the low water line to the
landward base of the sand dunes.
Cite this dataset when used as a source.
|Search and Download
|| Distributor information not available
| Point of Contact
Documentation links not available.
|Data Presentation Form:
|| Digital image
|Dataset Progress Status
|Data Update Frequency:
|| Not planned
||This data set was collected with a LIDAR (LIght Detection And Ranging) instrument
designed and developed by the Observational Sciences Branch (OSB) of NASA at the Wallops
Flight Facility in Virginia. The instrument, originally designed for mapping ice sheets
in Greenland, is called the Airborne Topographic Mapper or ATM. The ATM II (the latest
version), operates with a Spectra Physics laser transmitter, which provides a 7 nanoseconds
long, 250 microjoules pulse at a frequency-doubled wavelength of 523 nanometers in
the blue-green spectral region. The laser transmitter can function at pulse rates
from 2 to 10 kilohertz (kHz). The laser system with a separate cooling unit weighs
approximately 45 kilograms (kg) and requires approximately 15 amperes of power at
115 volts. The transmitted laser pulse is reflected to the surface of the earth with
the aid of a small folding mirror mounted on the back of a secondary mirror of a rotating
scan mirror assembly mounted directly in front of the telescope. The scan mirror,
which is rotated at 20 hertz, is comprised of a section of round aluminum stock, machined
to a specific off-nadir angle. A scan mirror with the off-nadir angle of 15 degrees
was utilized, producing an elliptical scan pattern with a swath width equal to 50
percent of the approximately 700-meter aircraft altitude. The reflected laser pulse
is transmitted to a photo-multiplier assembly that consists of a lens, a narrow bandpass
filter, and a single photomultiplier tube. Note: The Spatial Reference section of
this document may lack fully FGDC-compliant information regarding projection parameters
(i.e., Central meridian, false Northing, etc.). The State Plane or UTM Zone will be
supplied, and the corresponding parameters can be found in Appendix C of: Snyder,
John, 1987, Map Projections, a Working Manual (U.S. Geological Survey Professional
Paper 1395): Washington, U.S. Government Printing Office.
||This data was collected as part of an effort to map beach topography efficiently and
||1996-10-09 to 2000-11-02
|Spatial Reference System:
|Spatial Bounding Box Coordinates:
|Spatial Coverage Map:
- digital elevation model
- U.S. Coastline
- North Carolina
- South Carolina
- New Hampshire
- New Jersey
- New York
- Rhode Island
| Use Constraints
|| No constraint information available
|| Fee information not available.
|| Lineage statement not available.
- DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department
| Processing Steps
- The vertical values in this data set have been filtered through visual inspection
to find abnormally high and abnormally low values. In addition, this data was processed
using a spatial filtering program that identifies and discards outlier elevation measurements.
This program reads each elevation measurement within a file and identifies "spatially
close" points (i.e. those neighboring points within a fixed radius of the point).
The mean and standard deviation is calculated using the elevations of these points.
If the elevation difference from the mean of the point under consideration is more
than 2 standard deviations and greater than a defined distance the point is discarded.
- The NOAA National Geophysical Data Center (NGDC) received lidar data files via ftp
transfer from the NOAA Coastal Services Center. The data are
currently being served via NOAA CSC Digital Coast at http://www.csc.noaa.gov/digitalcoast/.
The data can be used to re-populate the system. The data are archived in LAS
or LAZ format. The LAS format is an industry standard for LiDAR data developed by
the American Society of Photogrammetry and Remote Sensing (ASPRS); LAZ is a loseless
compressed version of LAS developed by Martin Isenburg (http://www.laszip.org/). The
data are exclusively in geographic coordinates (either NAD83 or ITRF94). The data
are referenced vertically to the ellipsoid (either GRS80 or ITRF94), allowing for
the ability to apply the most up to date geoid model when transforming to orthometric
Metadata Last Modified: 2013-05-07
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