Comparison of SeaWiFS and MODIS time series of inherent optical properties for the Adriatic Sea

Abstract

Time series of inherent optical properties (IOPs) derived from SeaWiFS and MODIS are compared for the Adriatic Sea. The IOPs are outputs of the Quasi-Analytical Algorithm and include total absorption <i>a</i>, phytoplankton absorption <i>a</i>_ph, absorption associated with colored detrital material (CDM) <i>a</i>_cdm, and particle backscattering coefficient <i>b</i>_bp. The average root-mean square difference Δ computed for log-transformed distributions decreases for $a$ from 0.084 at 412 nm to 0.052 at 490 nm, is higher for <i>a</i>_ph(443) (0.149) than for <i>a</i>_cdm(443) (0.071), and is approximately 0.165 for <i>b</i>_bp at various wavelengths. The SeaWiFS <i>a</i> at 443 and 490 nm, <i>a</i>_ph at 443 nm and <i>b</i>_bp are on average higher than the MODIS counterparts. Statistics show significant variations in space and time. There is an overall increasing gradient for Δ associated with the absorption terms from the open southern and central Adriatic to the northwest part of the basin, and a reversed gradient for the particulate backscattering coefficient. For time series analysis, only <i>a</i>(412) and <i>a</i>_cdm(443) currently present an unbiased continuity bridging the SeaWiFS and MODIS periods for the Adriatic Sea.