Current Regional Coverage (Clickable)
Landsat 7 Landsat 5 IKONOS Masks
Global n/a Global n/a
N Caribbean n/a Thumbnail Images Cuba
E Caribbean n/a Caribbean n/a
W Caribbean W Caribbean n/a n/a
Australia n/a n/a n/a
Micronesia n/a n/a n/a
Melanesia n/a n/a New
Polynesia n/a n/a n/a
SE Asia SE Asia n/a n/a
Indian Ocean
n/a n/a n/a
Indian Ocean
n/a n/a n/a
Eastern Seas
n/a n/a n/a
The boundaries of the reef regions
depicted in the maps is as defined in
the UNEP-WCMC atlas of coral reefs,
Spalding (2001).

Image Database

NASA funding allowed IMaRS to complete the image database in 2005. The NASA program provided substantial assistance with image acquisition. The main data set is an archive of Landsat 7 images. The Landsat 7 satellite has been operational since mid-1999 and has collected tens of thousands of coral reef scenes in the framework of the Long Term Acquisition Plan (LTAP) of the Landsat Program. As participant to the Landsat Science Team, IMaRS advocated a specific acquisition strategy for coral reefs and proposed a specific strategy using input from nearly 50 institutions worldwide that participate via the NOAA Coral Health and Monitoring Program List-Server. LTAP made this proposition a reality by implementing a plan for reefs in 1999 (Arvidson et al. 2001). Using the existing global coral reef map produced by (UNEP WCMC, ReefBase), we estimate that almost 900 Landsat scenes need to be processed to complete a global inventory (Gasch et al. 2000). The entire Landsat 7 archive is periodically inspected to identify the best image for one particular area. As of 2007 the database contains more than 1700 Landsat 7 images. This premier Landsat 7 data set is complemented by a substantial amount of Landsat 5 data acquired in the early nineties (mostly of the Caribbean and Central America), by SPOT images (mostly of French coral reefs in the Pacific Ocean), by several ASTER images (Red Sea and Pacific Ocean) and by a unique dataset of very high spatial resolution IKONOS images. The NASA Scientific Data Purchase Program (SDP) provided the Landsat 5 and IKONOS images.

The principal data set consists of recent (1999-2002), generally cloud-free, Landsat 7 ETM+ imagery. For images in which cloud cover is not optimal Landsat 5 TM, SPOT imagery and/or International Space Station digital photographs have or will be used. The problem of different acquisition dates between images is negligible because we mostly map geomorphological zones that do not change, even on a decadal scale. Different spatial resolutions between images also have only a minor impact (Andréfouët et al. (2003)).

On an opportunistic basis, some very high-resolution data (aerial photographs) are used to refine the interpretation of the Landsat images, but we do not attempt to systematically collect archived aerial photographs. A selection of IKONOS images covering all kinds of reef configurations worldwide is also used to compare Landsat products with higher resolution products (Andréfouët et al. (2003)). In addition, astronauts are continually increasing the new catalog of high-resolution (6 m) digital photographs of coral reefs taken from the International Space Station (Robinson and Evans, 2002), which also allow validation of products.

The second data set is not directly used to map reefs, but to estimate atmospheric parameters over the targets acquired by Landsat and to populate the metadata-base of image processing parameters. We will use SeaWiFS/MODIS images, quasi-concurrent to Landsat 7 ETM+ overpasses to estimate aerosol types and their contribution to the total signal. We will follow the method described in Hu et al. (2001).