Estimation of ocean contribution at the MODIS near-infrared wavelengths along the east coast of the U.S.: Two case studies

[1] Atmospheric correction for the ocean color products derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) uses two near-infrared (NIR) bands centered at 748 and 869 nm. Ocean is usually assumed to be black at these two NIR wavelengths. For Case-2 and high productive Case-1 waters, however, ocean could have significant contributions in the NIR, leading to significant under-estimation of the MODIS-derived waterleaving radiances. This is often the case in coastal regions. In this paper, measurements from the MODIS Terra at the short wave infrared (SWIR) wavelengths (1240 and 1640 nm) are used to evaluate the ocean contributions at wavelengths 748 and 869 nm. The ocean is black in coastal regions in these SWIR bands due to much stronger water absorption. Studies of two MODIS granules off the east coast of the U.S. show that the ocean could have reflectance values of 3.1% and 1.8% at the top of atmosphere (TOA) for bands 748 and 869 nm in the Outer Banks, while these values are 0.15% and 0.1% in the Chesapeake Bay region. Thus, for the turbid waters, it is important to accurately account for the ocean contributions in the NIR bands for the atmospheric correction of ocean color remote sensing. Citation: Wang, M., and W. Shi (2005), Estimation of ocean contribution at the MODIS near-infrared wavelengths along the east coast of the U.S.: Two case studies, Geophys. Res. Lett., 32, L13606, doi:10.1029/2005GL022917.