Ocean color patterns help to predict depth of optical layers in stratified coastal waters

Abstract

Subsurface optical layers distributed at two different depths were investigated in Monterrey Bay, East Sound, and the Black Sea based on spatial statistics of remote sensing reflectance (Rrs). The main objective of this study was to evaluate the use of Rrs(443)/Rrs(490) (hereafter R1) skewness (ψ) as an indicator of vertical optical structure in different marine regions. Measurements of inherent optical properties were obtained using a remotely op- erated towed vehicle and R1 was theoretically derived from optical profiles. Although the broad range of trophic status and water stratification, a common statistical pattern consist- ing of lower ψR1—a deeper optical layer was found in all study cases. This variation was attributed to optical changes above the opticline and related to horizontal variability of par- ticulates and spectral variations with depth. We recommend more comparisons in stratified coastal waters with different phytoplankton communities before the use of ψR1 can be gener- alized as a noninvasive optical proxy for screening depth changes on subsurface optical layers.