Atmospheric correction using 1240 and 2130 nm combination of MODIS SWIR channels

Abstract

It is essential to improve understanding of coastal ocean since the majority of the world's primary production occurs on continental shelves and the coastal ocean is most utilized and impacted by humans. The first step in ocean-colour data processing is the removal of atmospheric contribution from the sensor-detected radiance to enable detection of optically active oceanic constituents e.g. chlorophyll-a, suspended sediment etc. Black ocean assumption at the near infrared (NIR) wavelengths as applied to perform atmospheric correction fails for coastal turbid waters due to the presence of highly scattering sediments which cause sufficient water-leaving radiance in NIR wavelengths and lead to over-estimation of aerosol radiance for λ <700nm resulting in negative water leaving radiance for λ <500nm. The assumption of zero water-leaving radiance at the NIR wavelengths was replaced by the assumption of zero water-leaving radiance at the short wave infrared (SWIR) wavelengths over the coastal turbid waters and atmospheric correction was performed using these SWIR wavelengths. Physically realistic and positive water leaving radiances throughout the spectrum and especially for shorter wavelengths (412nm, 443nm, 490nm) were obtained over coastal turbid waters using this concept.