Before revision: It should be noted that although grid cells are spaced at 15 or 30 arc-seconds, when SONAR measurements are unavailable, the resolution is much worse (~20-12 km) depending on factors such as water depth.
After revision: Although grid cells are spaced at 15 or 30 arc-seconds, when SONAR measurements are unavailable, the resolution is much worse (~20-12 km) depending on factors such as water depth.