INITIAL RESULTS FROM A TEST OF THE NASA EXPERIMENTAL ADVANCEDAIRBORNE RESEARCH LIDAR (EAARL) FOR THE STUDY OF CORAL REEFECOSYSTEMS

摘要

Synoptic maps of coral communities based on satellite images generally portray only coarsegeomorphological zones and generally are not sufficiently detailed or accurate to be of highvalue to biologists. Aircraft-based hyperspectral sensors can acquire finer scale images, but aretypically quite expensive. Further, water-column contamination of the light reflected from reefbenthic classes typically diminish the accuracy of thematic maps derived from aircraft or satellitescanning.The NASA Experimental Advanced Airborne Research Lidar (EAARL) is intended to mitigatethese difficulties by combining a hyperspectral scanner with a laser bathymetric sounder on alow cost aircraft. Geopositioning of the Cessna 310 aircraft used for initial flight tests wasachieved by the use of an array of GPS antennas that provide both the aircraft flight trajectory(longitude, latitude, altitude) and attitude (pitch, roll, heading). The NASA EAARL instrumentpackage also includes a downlooking digital camera that acquires digital images at a rate of oneper second, or roughly every 50 meters along track, during flight operations.Initial flights based at Marathon, Florida were conducted over the Florida Keys reef tract fromDry Tortugas National Park (DTNP ) to Biscayne National Park (BNP). Data was continuouslyacquired over numerous known reefs in transit to two regions that were swath-mapped, 1) thecoral community in central BNP, and 2) an area undergoing rapid channel sedimentation inDTNP. The GPS, flight navigation, and camera and lidar systems performed within designspecifications, and lidar reflections were observed from water depths greater than 15 meters.