NOAA REMOTE SENSING EXPERTISE AIDS WORLD TRADE CENTER RECOVERY EFFORTS
September 28, 2001 NOAA's National Geodetic Survey and Aircraft Operations Center mapped the wreckage of the World Trade Center in support of recovery and cleanup efforts following the Sept. 11 terrorist attack. The data are being used to provide a very accurate geographic network. Building and utility engineers will be able to determine the location of original foundation support structures, elevator shafts, basement storage areas and building utility connections enabling them to concentrate their digging and recovery efforts in the proper location.
These images will also provide very accurate height measurements as the recovery efforts descend into the basement, to mitigate possible flooding from the surrounding rivers as well as to determine the volume of debris and the reach needed by cranes to remove it.
(See graphic legend below.)
On the LIDAR image above the following colors correspond
with the following elevations relative to mean sea level.
NOAA's efforts in New York
began on the ground on Sept. 15th as NGS field survey personnel
provided the necessary ground support and calibration expertise
for the airborne imaging sensorshigh resolution cameras
and laser ranging devices. These airborne and ground-based systems
will produce very accurate map products at ground zero and the
surrounding area affected by the terrorist attack. Both private
team used the global positioning system (GPS)
to position both ground and airborne mapping sensors. GPS technology
fixes the latitude, longitude and height of a point on the ground
and in space within five centimeters. Additional support was
provided by the NGS Continuously Operating Reference Stations
(CORS) program, which
used two of its nearby continuously operating GPS sites to collect
data for the remote sensing missions.
The NOAA Citation jet, N52RF, usually used for remote sensing and high resolution photography for coastal mapping, was outfitted with an Optech LIDAR (Light Detection and Ranging). Collecting both LIDAR data and high-resolution photography, the Citation flew over a five-square kilometer area of lower Manhattan.
Flights over the World Trade Center took place Sept. 23 and Sept. 26. There were two flights lasting four hours each. The NOAA Citation jet flew at an altitude of 5,000 to 6,000 feet.
The NGS field support team included Mike Aslaksen, Ed Carlson, and Jason Woolard. The Citation crew included Lt. Cmdr. Brad Kearse, Lt. Mike Weaver, and Lt. Will O'Dell (pilots) of the NOAA Commissioned Corps and Aircraft Operations Center; and Steve Nicklas of NGS.
The U.S. Army Joint Precision Strike Demonstration initiated and coordinated the entire effort. Army JPSD worked closely with NOAA, Optech Inc. and the University of Florida to produce the images and map products.
Relevant Web Sites
Light Detection and Ranging (LIDAR) with sample images
NOAA's Coastal Aerial Photography