Consequently, atmospheric radiative forcing over the oceans is poorly understood. The oceans themselves have distinct radiative regions. For example, consider the short wavelength sunlight reflected by the upper ocean. The subtropical and tropical ocean basins, which comprise the largest surface area of the ocean, are characterized by optically clear waters with low concentrations of absorbing particles. Additionally, such platforms are expensive and difficult to support continuously or for extended periods.
Atolls are potentially suitable sites because of their profile, however atolls are coral outgrowths.
Coral skeletons are composed of calcium carbonate, which is highly optically reflective. Additionally, planktonic biota found in the waters in the immediate vicinity around atolls often contains organisms with calcium carbonate skeletons. Thus measurements of the surface ocean reflective radiation field made from an atoll may be badly biased relative to the true case 1 condition which may exist only a few kilometers from the atoll itself. Alternate platforms, such as old oil-drilling platforms, may therefore be important locations for deploying equipment. Another consideration in selecting a siting strategy for ARM is the possibility that other anthropogenic factors may be affecting the Earth's radiation budget.