Influence of the spatial resolution of SeaWiFS, Landsat-7, SPOT, and International Space Station data on estimates of landscape parameters of Pacific Ocean atolls

Perimeter, surface area, total hydrodynamic aperture, and degree of hydrodynamic aperture are key landscape parameters used to quantify differences in the biological functioning of Tuamotu Archipelago atolls (French Polynesia). In a previous study, these landscape parameters were computed using Satellite pour l'observation de la terre (SPOT) high-resolution visible (HRV) data at 20 in spatial resolution. Since 1999, Tuamotu atolls have been systematically imaged by an array of satellite sensors with a wide range of spatial resolution (from I km to 5 in) including the sea-viewing wide field-of-view sensor (SeaWiFS), Landsat enhanced thematic mapper plus (ETM+), and digital photographs taken by astronauts from the International Space Station (ISS). Our goal was to assess the influence of the spatial resolution of SeaWiFS (I km), ETM+ (30 in), HRV (20 in), and ISS digital photographs (5 in) on the estimation of landscape parameters of Pacific Ocean atolls. Total hydrodynamic aperture and degree of hydrodynamic aperture are the parameters most sensitive to variation in resolution. For the same atoll, the differences between degree of aperture computed from SPOT and Landsat can reach 28%. Conversely, perimeters and atoll surface area estimates are in agreement within 7% using data with resolution from 5 to 30 in. One kilometre resolution SeaWiFS data offer the possibility to rank atolls based on surface area correctly, but only for atolls larger than 70 km(2).