An Autonomous Marine Optical System (AMOS) for monitoring the optical properties of port and harbor waters

Abstract

The Autonomous Marine Optical System (AMOS) measures remote sensing reflectance (R_rs) above the water surface and subsurface optical properties (irradiance at depth, beam attenuation, chlorophyll fluorescence, and light backscattering) at predetermined times throughout the day. Data are transmitted back by radio to a networked archival and processing station. AMOS was created to routinely monitor the optical properties of near-surface waters, and make those measurements available to researchers over an Ethernet connection with minimal delay. The Rrs measurements can be used not only to validate satellite and airborne remote sensing imagery, but also to be combined with the in situ measurements so that other water column properties can be estimated. The performance of visible and machine-aided hull inspection is strongly affected by the optical properties of the water. AMOS estimates of these optical properties can be used by optical models to predict both subsurface visibility and the amount of ambient light beneath ships at port inspection sites. An example of the application of an inverse hyperspectral Rrs model to AMOS data from the Port of St. Petersburg (FL) is shown to accurately estimate light absorption due to phytoplankton and colored dissolved organic matter (CDOM), and backscattering due to particles.