EAARL Coastal Topography--Pearl River Delta 2008: Bare Earth

A bare earth elevation map (also known as a Digital Elevation Model, or DEM) of the Pearl River Delta in Louisiana and Mississippi was produced from remotely sensed, geographically referenced elevation measurements cooperatively by the U.S. Geological Survey (USGS), the University of New Orleans (UNO), and the National Aeronautics and Space Administration (NASA). Elevation measurements were collected over the area using the NASA Experimental Advanced Airborne Research Lidar (EAARL), a pulsed-laser ranging system mounted onboard an aircraft to measure ground elevation, vegetation canopy, and coastal topography. The system uses high-frequency laser beams directed at the Earth's surface through an 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 plane travels over the target area at approximately 50 meters per second at an elevation of approximately 300 meters. The EAARL, developed by NASA at Wallops Flight Facility in Virginia, measures ground elevation with a vertical resolution of 15 centimeters. A sampling rate of 3 kilohertz or higher results in an extremely dense spatial elevation dataset. Over 100 kilometers of coastline can be easily surveyed within a 3- to 4-hour mission. When subsequent elevation maps for an area are analyzed, they provide resource managers with a useful tool regarding land development.

美国地质调查局（U.S. Geological Survey, USGS）、新奥尔良大学（University of New Orleans, UNO）与美国国家航空航天局（National Aeronautics and Space Administration, NASA）合作，基于遥感地理参考高程测量数据，制作了路易斯安那州与密西西比州珍珠河三角洲的裸地高程地图，又称数字高程模型（Digital Elevation Model, DEM）。该数据集采用美国国家航空航天局实验先进机载研究激光雷达（NASA Experimental Advanced Airborne Research Lidar, EAARL）采集研究区域的高程数据，这是一款搭载于机载平台的脉冲激光测距系统，可同步测量地面高程、植被冠层与海岸地形。该系统通过飞机机身底部的开口向地表发射高频激光束，并记录激光束发射与机载平台接收反射激光信号之间的时间差，以此完成距离测算。作业飞机在目标区域上空的飞行高度约为300米，飞行速度约为50米每秒。由美国国家航空航天局弗吉尼亚州沃洛普斯飞行设施研发的EAARL，其地面高程测量的垂直分辨率可达15厘米。当采样率达到3千赫及以上时，即可生成空间密度极高的高程数据集。单次3至4小时的飞行任务即可轻松完成超过100公里海岸线的测绘工作。当对某一区域的多期高程地图进行分析时，可为资源管理者提供用于土地开发相关决策的实用工具。