removed from chlorophyll calculations since they are representative ocean waves or the angle of the sun instead of the subsurface ocean. The process of removing these components is called atmospheric correction. A description of the light, or radiance, observed by the satellite's sensor can be more formally expressed by the following radiative transfer equation: Where LT(λ) is total radiance at the top of the atmosphere, Lr(λ) is Rayleigh scattering by air molecules, La(λ) is scattering by aerosols in the absence of air, Lra(λ) is interactions between air molecules and aerosols, TLg(λ) is reflections from glint, t(Lf(λ) is reflections from foam, and LW(λ)) is reflections from the subsurface of the water, or the water-leaving radiance. Others may divide radiance into some slightly different components, though in each case the reflectance parameters must be resolved in order to estimate water-leaving radiance and thus chlorophyll concentrations. Data products Though SeaWiFS was designed primarily to monitor ocean concentrations from space, it also collected many other parameters that are freely available to the public for research and educational purposes. These parameters aside from include reflectance, the diffuse attenuation coefficient, particulate organic carbon (POC) concentration, particulate inorganic carbon (PIC) concentration, colored dissolved organic matter (CDOM) index, photosynthetically active radiation (PAR), and normalized fluorescence line height (NFLH). In addition, despite being designed to measure ocean chlorophyll, SeaWiFS also estimates Normalized Difference Vegetation Index (NDVI), which is a measure of photosynthesis on land. Data access SeaWiFS data are freely accessible from a variety of websites, most of which are government run. The primary location for SeaWiFS data is NASA's OceanColor website , which maintains the time series of the entire SeaWiFS mission. The website allows users to browse individual SeaWiFS images based on time and area selections. The website also allows for browsing of different temporal and spatial scales with spatial scales ranging from 4 km to 9 km for mapped data. Data are provided at numerous temporal scales including daily, multiple days (e.g., 3, 8), monthly, and seasonal images, all the way up to composites of the entire mission. Data are also available via ftp and bulk download. Data can be browsed and retrieved in a variety of formats and levels of processing, with four general levels from unprocessed to modeled output. Level 0 is unprocessed data that is not usually provided to users. Level 1 data are reconstructed but either unprocessed or minimally processed. Level 2