Retrieval of suspended particulate matter from turbidity: model development, validation, and application to MERIS data over the Baltic Sea
(English)Manuscript (preprint) (Other academic)
Suspended Particulate Matter (SPM) causes most of the scattering in natural waters and thus has a strong influence on the underwater light field and consequently to the whole ecosystem. The evaluation of the environmental status of the Baltic Sea can be improved by monitoring SPM. However, SPM is not included in monitoring programs due to the laborious gravimetrical method. In this study we aim to provide an alternative method to retrieve SPM from both in situ and satellite-based turbidity. An in situ dataset was collected in Swedish coastal areas of the north-western Baltic Sea during 2010-2014 to develop a regional SPM model. The model was then applied to turbidity retrieved from single band remote sensing reflectance (620 nm) measured by the ‘Medium Resolution Imaging Spectrometer’ (MERIS). The performance of the model was evaluated against independent datasets and compared to the MERIS standard SPM product. Despite the optical variability within the study areas, SPM and turbidity were linearly related and highly correlated (r=0.97). The developed model predicts SPM reliably from in situ turbidity (r2=0.93), with the mean normalized bias (MNB) 2.6% and the root mean square (RMS) 25.5%. Retrieving SPM from reflectance-based turbidity reduced the RMS from 47% to 40% and MNB from 11% to -4.9%, when compared to MERIS SPM product. Hence, the retrieval of SPM from reflectance-based turbidity has higher accuracy and lower bias than the MERIS SPM product. The SPM model provides a robust and cost-efficient method to determine SPM from both in situ and remote sensing data.
Turbidity, SPM, remote sensing, monitoring, water quality
Research subject Marine Ecology
IdentifiersURN: urn:nbn:se:su:diva-119715OAI: oai:DiVA.org:su-119715DiVA: diva2:847988
FunderSwedish National Space Board, 147/12Swedish Environmental Protection AgencyBaltic Ecosystem Adaptive Management (BEAM)Nordic Council of Ministers, 42041