Global shallow-water bathymetry from satellite ocean color data

Abstract

Knowledge of ocean bathymetry is important, not only for navigation but also for scientific studies of the ocean's volume, ecology, and circulation, all of which are related to Earth's climate. In coastal regions, moreover, detailed bathymetric maps are critical for storm surge modeling, marine power plant planning, understanding of ecosystem connectivity, coastal management, and change analyses. Because ocean areas are enormously large and ship surveys have limited coverage, adequate bathymetric data are still lacking throughout the global ocean. Satellite altimetry can produce reasonable estimates of bathymetry for the deep ocean [Sandwell et al., 2003, 2006], but the spatial resolution is very coarse (∼6-9 kilometers) and can be highly inaccurate in shallow waters, where gravitational effects are small. For example, depths retrieved from the widely used ETOPO2 bathymetry database (the National Geophysical Data Center's 2minute global relief data; http://www.ngdc.noaa.gov/mgg/fliers/ 01mgg04.html) for the Great Bahama Bank (Figure 1a) are seriously in error when compared with ship surveys [Dierssen et al., 2009] (see Figure 1b). No statistical correlation was found between the two bathymetry measurements, and the root-mean-square error of ETOPO2 bathymetry was as high as 208 meters. Yet determining a higher-spatial-resolution (e.g., 300-meter) bathymetry of this region with ship surveys would require about 4 years of nonstop effort.