Resolving the Subscale Spatial Variability of Apparent and Inherent Optical Properties in Ocean Color Match-Up Sites

A stochastic approach is developed to resolve the scale variability between point and aerospace measurements in ocean color match-up sites. The model used the differences between in situ and aerospace-observed spectra and ocean color model inversion to estimate the subscale variability of apparent and inherent optical properties (IOPs). The model was tested and validated against three sets of ocean color data: simulated, in situ measured, and satellite data sets. The results showed that the variability of chlorophyll-a absorption was derived with high accuracy. Errors in derived subscale variability of detritus-gelbstoff absorption and particle scattering were larger than those of chlorophyll-a. The subscale radiometric variability was found to be proportional to that of IOPs and decreased with increasing water turbidity. The subpixel variability of reduced resolution ocean color image was derived with less than 12% of relative errors in clear and moderate turbid waters. Larger errors were obtained in estuarine turbid waters. Better accuracy was obtained for match-up sites with high internal contrast, i.e., spatial variability.