Evaluation of the CDOM Absorption Coefficient in the Arctic Seas Based on Sentinel-3 OLCI Data

Abstract

Our work’s primary goal is to reveal the problematic issues related to estimates of the colored organic matter absorption coefficient in the northern seas from data of the Ocean and Land Color Instrument (OLCI) installed on the Sentinel-3 satellites, e.g., a comparison of the OLCI standard error assessment ADG443_NN_err relating to the measurement and the retrieval of the geophysical products and the uncertainties in the northern seas’ real situation. The natural conditions are incredibly unfavorable there, mainly due to frequent cloudiness and low sun heights. We conducted a comprehensive multi-sensor study of the uncertainties using various approaches. We directly compared the data from satellites (OLCI Sentinel-3 and four other ocean color sensors) and field measurements in five sea expeditions (2016–2019) using the different processing algorithms. Our analysis has shown that the final product’s real uncertainties are significantly (≥100%) higher than the calculated errors of the ADG443_NN_err (~10%). The main reason is the unsatisfactory atmospheric correction. We present the analysis of the various influential factors (satellite sensors, processing algorithms, and other parameters) and formulate future work goals.

CDOM Optical Properties and DOC Content in the Largest Mixing Zones of the Siberian Shelf Seas

“…The OLCI ocean color scanners launched in February 2016 (Sentinel-3A) and in April 2018 (Sentinel-3B) should provide satellite data in the next decade. It was shown by Glukhovets et al [31] that the standard OLCI algorithm for estimating the CDOM absorp-tion coefficient ADG443_NN gives high errors in the Arctic seas. The dataset presented in this work may be used to improve existing standard and regional [78] algorithms and to create new ones.…”

“…Obtained results on CDOM absorption can be valuable in remote sensing and modeling issues. For example, calculated from satellite data, CDOM absorption coefficients may be used as an effective indicator of the Kara Sea surface desalinated layer distribution and dynamics [31]. As the values of light absorption in this layer are significantly higher than in surrounding seawaters [56,77], its characteristics must be taken into account in heat budget models.…”

“…Thus, a great need for additional DOC data, which can only be obtained in the field, was emphasized by Harrison et al [28]. Taking into account the recent progress in development of quantitative CDOM and DOC determination with the use of satellite remote sensing [29,30], new field studies of DOC and optical properties of natural waters might be useful for validation of remote sensing models, as well as regional algorithms for estimation of absorption coefficient of colored organic matter [31].…”

Comparison of In Situ and Remote-Sensing Methods to Determine Turbidity and Concentration of Suspended Matter in the Estuary Zone of the Mzymta River, Black Sea

“…As a rule, however, for comparison with satellite data, either data from various PT analogs are used [77], or data from floating spectroradiometers that are widely employed today for validating satellite data obtained during field experiments. They measure absolute spectral irradiance at the sea surface and water leaving radiance immediately under the sea surface [78]. TM data are usually used for estimating river water penetration depth and turbidity profiling.…”

Verification and modification of satellite algorithms for evaluation of suspended matter concentration in the Kara Sea

“…However, these algorithms are based on a limited set of data and need validation. Previously, the validation of algorithms for estimating of the colored organic matter absorption coefficient 4 in the northern seas was performed. Measurements on cruises 72, 76, and 81 of the R/V «Akademik Mstislav Keldysh» (AMK) in 2018-2020 in the Kara Sea were used to test and modify the algorithms for estimation of the total suspended matter (TSM) concentration using data of MODIS and OLCI satellite ocean color scanners.…”