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El Niño Coastal Erosion Display Explanation
Elevation Change - elevation differences between lidar surveys obtained at the beginning (October 1997) and end (April 1998) of the El Niño winter. The change data (shown in color) are superimposed on the passive data (shown in black and white). To calculate the change, the elevation of each data point in one survey is differenced from all data that occur within 1 m horizontal in the other survey.

Passive Data - a "panchromatic" digital image of the coast that is obtained simultaneously with the laser elevation (lidar) measurements made by the NASA Airborne Topographic Mapper (ATM). The passive data are geo-referenced in a mosaic that appears as a 'strip' image of the coast. The post-El Niño (April 1998) passive data are shown in a strip map roughly 700 m wide.

strip map explanation Topography - derived from lidar data obtained in April 1998. To conserve space, the pre-El Niño survey obtained in October 1997 is not shown. Water (dark blue/purple) is to the left and land is to the right. The strip is roughly 700 m wide and follows the coastline.

Profile Comparisons - at selected locations shore-normal transects were defined. Profiles along these transects were determined from lidar surveys obtained in October 1997 and April 1998. Each data point shown represents a laser spot elevation. All spot elevations within 1 meter of the shore-normal transect were used to construct the profiles.

Example profile comparison
example transect graph