|Assembly of Landsat 7 Data for Coral Reef Mapping
The first challenge
for global coral reef mapping with Landsat 7 is in getting global data that is
not obscured by cloud cover. Global data acquisition for coral reef mapping
was initiated through the Landsat 7 Long Term Acquisition Plan (Gasch et al. 2000). Once the instrument began acquiring data over
coral reefs, it took several years to get the needed acquisitions because of
tropical cloud cover, and to find ways to purchase or trade for the over 1000
scenes necessary to complete the global coverage. The data assembly was led by
scientists in the Institute for Marine Remote Sensing (http://www.imars.usf.edu/MC/index.html) at the University of
South Florida. A number of groups within NASA provided Landsat scenes, and
collaborators in mapping projects around the world shared their data in
order to assemble the most complete possible archive of Landsat 7 data. The
archive and online data interface has been developed by the SeaWiFS Project at
Goddard Spaceflight Center.
At present, two different online products allow access to the data:
- A Landsat Coral Reef Data Archive displays data that is tiled, zoomable, and downloadable via FTP
- An index with browse images of all the Landsat 7 data assembled by region (http://imars.marine.usf.edu/corals/maps/reef_count.html)
A total of 1490 Landsat 7 scenes were acquired with all but 55 available for public distribution. The archive is considered complete (with at least one good scene per target path-row).
The collection of this set of global data was a necessity of the Millennium Coral Reef Mapping project (see next), and satisfies a need identified by members of the U.S. Coral Reef Taskforce. By assembling these data in a single freely accessible location, the use of Landsat data in a variety of local, regional, and global mapping projects will become possible.