A review on substances and processes relevant for optical remote sensing of extremely turbid marine areas, with a focus on the Wadden Sea

Abstract

The interpretation of optical remote sensing data of estuaries and tidal Xat areas is hampered by optical complexity and often extreme turbidity. Extremely high concentrations of suspended matter, chlorophyll and dissolved organic matter, local diVerences, seasonal and tidal variations and resuspension are important factors inXuencing the optical properties in such areas. This review gives an overview of the processes in estuaries and tidal Xat areas and the implications of these for remote sensing in such areas, using the Wadden Sea as a case study area. Results show that remote sensing research in extremely turbid estuaries and tidal areas is possible. However, this requires sensors with a large ground resolution, algorithms tuned for high concentrations of various substances and the local speciWc optical properties of these substances, a simultaneous detection of water colour and land-water boundaries, a very short time lag between acquisition of remote sensing and in situ data used for validation and suYcient geophysical and ecological knowledge of the area.

Integration of in-situ and multi-sensor satellite observations for long-term water quality monitoring in coastal areas

“…The highest values of retrieved SPM mainly occur in ]) when there are more storms through the Dutch Wadden Sea, which causes higher levels of upwelling SPM. Whereas, the lowest SPM values mainly occur in ]) for all years, which confirms previous work in the area (Hommersom et al, 2010a(Hommersom et al, , 2010b.…”

“…Effective monitoring of this area needs continuous tracking of the spatio-temporal variations of WCCs in order to capture information on dynamic events, which might have a substantial impact on ecosystems, such as changes caused by storms or unexpected phytoplankton blooms (Zevenboom et al, 1991). However, the climatological conditions of the Dutch Wadden Sea, characterized by frequent cloudiness, various combinations of three WCCs, besides the tide-modulated shallowness of the water, make this region a complex case study for water quality monitoring using remote sensing approaches (Arabi et al, 2019;Hommersom et al, 2010aHommersom et al, , 2010bMisdorp et al, 1989;Müller et al, 2016).…”

Spatial distribution of penetration depth in Taihu Lake (China) during spring and autumn

“…This assumption can potentially lead to large errors when there is considerable spatial variation of the penetration depth (Liang and Chen, 1989). Algorithms need to be tuned for different penetration depths in different regions of the same water body (Hommerson et al, 2010).…”

Optical Satellite Remote Sensing of the Coastal Zone Environment — An Overview

“…There are mainly two approaches for deriving water-quality products from remotely sensed data: the model-based and the empirical approach. The model-based (or analytical) approach seeks to model the remote-sensing reflectance in terms of the water IOPs through radiative transfer modeling [62]. The remote-sensing reflectance from the water IOPs is obtained through a bio-optical model and an approximation of the radiative transfer equation [63] or through direct solution of the Radiative Transfer Equation (RTE).…”