3.2 LOW SPATIAL RESOLUTION (≥500 METER) GLOBAL OCEAN PRODUCTS
3.2.1 SeaWiFS 1-km shallow bathymetry
The Stumpf et al. (2003a) bathymetry algorithm has been applied to all the
SeaWiFS (Sea-viewing Wide Field-of-view Sensor) data for the five-year mission to
produce a global composite map with 0.01 degree map resolution (Stumpf et al.,
2003b). The high positional accuracy of SeaWiFS made it possible to build a
composite map and allowed elimination of clouds and short-term turbidity events to
produce a uniform global bathymetry map. The dataset is available through the
SeaWiFS Project (http://seawifs.gsfc.nasa.gov/reefs/ ) (Figure 1) and through ReefBase
(Figure 1C; http://www.reefbase.org). In areas of frequent turbidity, the shallowest
depths are underestimated, however, the algorithm performed well compared to
reference data.
3.2.2
Sea Surface Temperatures
Warming of the oceans due to global climate change has the potential to induce
major coral bleaching episodes around the world (Hoegh-Guldberg, 1999), and
understanding patterns of anomalous temperatures near coral reefs is important for reef
and fisheries management. Of the variety of different sea surface temperature analyses
being conducted globally, a few have great potential for synthesis with other remote
sensing data in improving understanding of coastal ecosystems. The U.S. National
Oceanographic and Atmospheric Administration (NOAA) provides a number of
operational (frequently updated) products on global sea surface temperature and
anomalies. Weekly and monthly datasets produced from the Polar-orbiting Operational
Environmental Satellite (POES) Advanced Very High Resolution Radiometer
(AVHRR) combined with buoy observations for field validation (Reynolds, 1988,
Reynolds et al., 2002) provide coarse global coverage with 1º mapping units. The
AVHRR Pathfinder algorithm allows improved spatial resolution in sea surface
temperature determination with 9 km mapping units (Kilpatrick et al., 2001).
Since 1997, NOAA has provided experimental AVHRR maps of sea surface
temperature anomalies with 50 km mapping units for the express purpose of evaluating
and predicting the incidence of coral bleaching events (Strong et al., 1997). Sea surface
temperature maps and estimates of cumulative thermal stress in terms of degree heating
weeks have been successful at predicting and monitoring coral bleaching events around
the world (e.g. Liu et al., 2003). For the large-scale bleaching events on the Great
Barrier Reef in 1998 and 2002, the maximum sea surface temperature occurring over
any 3-day period (“max3d”) predicted bleaching better than anomaly-based
methods (Berkelmans et al., 2004). Higher resolution (9 km mapping units)
temperature anomaly products can further refine and improve the ability to predict coral
bleaching (Toscano et al., 2002a, b). Products are under continued revision and
development zand are available from NOAA’s Coral Reef Watch (http://orbitnet.nesdis.noaa.gov/orad/coral_bleaching_index.html). Degree Heating Weeks data are also
shared with the ReefBase online GIS server (Figure 1, D; http://www.reefbase.org)).
The Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Terra
and Aqua satellites also makes observations of sea surface temperatures, chlorophyll
and many other bio-optical products. The “level 2” daily data has 1 km spatial
resolution, and global binned map products (“level 3”, including quality control and
eliminating most cloud cover) for ocean color and sea surface temperature are available
290
Robinson, Andréfouët and Burke
3.2.1 SeaWiFS 1-km shallow bathymetry
The Stumpf et al. (2003a) bathymetry algorithm has been applied to all the
SeaWiFS (Sea-viewing Wide Field-of-view Sensor) data for the five-year mission to
produce a global composite map with 0.01 degree map resolution (Stumpf et al.,
2003b). The high positional accuracy of SeaWiFS made it possible to build a
composite map and allowed elimination of clouds and short-term turbidity events to
produce a uniform global bathymetry map. The dataset is available through the
SeaWiFS Project (http://seawifs.gsfc.nasa.gov/reefs/ ) (Figure 1) and through ReefBase
(Figure 1C; http://www.reefbase.org). In areas of frequent turbidity, the shallowest
depths are underestimated, however, the algorithm performed well compared to
reference data.
3.2.2
Sea Surface Temperatures
Warming of the oceans due to global climate change has the potential to induce
major coral bleaching episodes around the world (Hoegh-Guldberg, 1999), and
understanding patterns of anomalous temperatures near coral reefs is important for reef
and fisheries management. Of the variety of different sea surface temperature analyses
being conducted globally, a few have great potential for synthesis with other remote
sensing data in improving understanding of coastal ecosystems. The U.S. National
Oceanographic and Atmospheric Administration (NOAA) provides a number of
operational (frequently updated) products on global sea surface temperature and
anomalies. Weekly and monthly datasets produced from the Polar-orbiting Operational
Environmental Satellite (POES) Advanced Very High Resolution Radiometer
(AVHRR) combined with buoy observations for field validation (Reynolds, 1988,
Reynolds et al., 2002) provide coarse global coverage with 1º mapping units. The
AVHRR Pathfinder algorithm allows improved spatial resolution in sea surface
temperature determination with 9 km mapping units (Kilpatrick et al., 2001).
Since 1997, NOAA has provided experimental AVHRR maps of sea surface
temperature anomalies with 50 km mapping units for the express purpose of evaluating
and predicting the incidence of coral bleaching events (Strong et al., 1997). Sea surface
temperature maps and estimates of cumulative thermal stress in terms of degree heating
weeks have been successful at predicting and monitoring coral bleaching events around
the world (e.g. Liu et al., 2003). For the large-scale bleaching events on the Great
Barrier Reef in 1998 and 2002, the maximum sea surface temperature occurring over
any 3-day period (“max3d”) predicted bleaching better than anomaly-based
methods (Berkelmans et al., 2004). Higher resolution (9 km mapping units)
temperature anomaly products can further refine and improve the ability to predict coral
bleaching (Toscano et al., 2002a, b). Products are under continued revision and
development zand are available from NOAA’s Coral Reef Watch (http://orbitnet.nesdis.noaa.gov/orad/coral_bleaching_index.html). Degree Heating Weeks data are also
shared with the ReefBase online GIS server (Figure 1, D; http://www.reefbase.org)).
The Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Terra
and Aqua satellites also makes observations of sea surface temperatures, chlorophyll
and many other bio-optical products. The “level 2” daily data has 1 km spatial
resolution, and global binned map products (“level 3”, including quality control and
eliminating most cloud cover) for ocean color and sea surface temperature are available
290
Robinson, Andréfouët and Burke