The first of the three images above is a scaled-down
version of the most recent global composite of SeaWiFS
one-kilometer data that have been passed through
a depth-classification algorithm. The second image
shows coral reef locations in red. This image was
created by the World
Conservation Monitoring Centre
using data from a variety of navigational charts
and other maps, and is available online through
Interactive Map Server, or in the published World
Atlas of Coral Reefs (Spalding et al. 2001). The
third image shows the locations of images from a variety
of sensors which can be viewed with this interface.
Click on any of the three images above to view the
full-resolution SeaWiFS bathymetry data for the location
clicked upon. You can remove any of the images above by
clicking on the appropriate buttons.
SeaWiFS Bathymetry Description
Characterizing water depth in tropical oceans is an
important first step for improving the identification
and characterization of coral reefs. NOAA scientists
have developed a new bathymetry algorithm,
originally applied to 4-meter IKONOS imagery (Stumpf
et al. 2003b), that could be applied
to other instruments with blue and green
bands. The algorithm was used to produce a global
composite 1-km bathymetry map from using SeaWiFS data (Robinson
et al. 2000, Stumpf et al. 1999, 2003a).
The value of each pixel in the full-resolution SeaWiFS
depth classification image is derived from depths computed
from different SeaWiFS overflights so that cloud pixels
can be removed and best depth estimates developed that
eliminate transient effects of sediment, chlorophyll,
etc. We have used the median measurement (after cloud
pixels have been removed) to represent each 0.01 by 0.01
degree location on the map.
The most current SeaWiFS-derived depth map was updated on 6
November 2002 and represents the contribution of 28,937 GAC
resolution files (all five years of the SeaWiFS mission),
25,682 recorded LAC-resolution files and 1,804 HRPT station
files from all around the world. The image below shows how
many separate SeaWiFS pixels (including cloudy pixels)
were used to determine each pixel on the final map. As
of 13 November 2002, no map pixel had fewer than 4 input
pixels, and many had more than 200.
The source data for the bathymetric images displayed
at this website are available
The global SeaWiFS bathymetry map has been used to
identify and correct errors in the UNEP-WCMC Reef Map.
Combining the SeaWiFS bathymetry product with the WCMC
map has increased map accuracy for use in evaluating the
global distribution of marine protected areas (Green et
al. in review).
Data Archive Proof-of-Concept
This web interface was also developed as a
proof of concept for the use of remotely sensed
earth observations from various platforms in
the mapping of coral reefs around the globe. A NASA-sponsored
partnership between remote sensing scientists,
international agencies and NGOs has developed from this
prototype, and a full Landsat
Coral Reef Data Archive is now available.
Other data sets displayed by this interface include:
AVIRIS Hyperspectral data collection was conducted with a
NASA high altitude aircraft over the Hawaiian islands in
April 2000. Preliminary data processing has been completed
at NASA's Jet Propulsion Laboratory and tapes containing
lines are being sent to NASA/Goddard Space
Flight Center for further processing and distribution.
This work is a joint project of: