Projects per year
Abstract
Ocean colour remote sensing (OCRS) from satellite platforms has revolutionised our ability to monitor the interplay of physical and biogeochemical processes in surface waters of the ocean. Since the launch of SeaWiFS in 1996, a continuous time series of OCRS data has been accumulated from a series of satellite sensors giving near daily global coverage. These sensors measure top of atmosphere (TOA) spectral radiance which is corrected for atmospheric effects (~80% of the measured signal in the blue - Gordon 1978) to give water leaving radiances. From these putrely optical signals, it is possible to derive a wide range of higher level products such as chlorophyll concentration, diffuse attenuation coefficients, photosynthetically available radiation (PAR) and a wide range of inherent optical properties (IOPs) to name but a few.
In terms of surface area and primary productivity, the global ocean is heavily dominated by deep, oceanic waters, where the optical properties are driven by phytoplankton, associated dissolved organics and water itself. It is little surprise then that early standard OCRS products were developed for optimal performance over these globally significant regions. Standard chlorophyll algorithms were developed using changes in blue-green reflectance ratios (e.g. O’Reilley et al., 1998) that can be related to the effect of changing concentrations of microscopic scale (1µm-200µm) phytoplankton (Kirk,1983) forming blooms that can stretch for thousands of km. More recently, attention has shifted to economically important coastal regions where, for example, harmful algal blooms have potential to cause significant societal and economic impact. OCRS algorithms have been developed to specifically aid in the monitoring of both toxic species e.g. Karenia brevis in the Gulf of Mexico (Stumpf et al., 2003), and also to monitor for extreme eutrophication events where excessive levels of phytoplankton cause the reduction of oxygen dissolved in the water column (hypoxia) leading to animal mortality (e.g. Mallin et al., 2006).
The optically complex nature of coastal waters, more generally, presents a particular problem for OCRS applications in these regions. Shallow shelf seas and other inshore waters are subject to the influence of sediment resuspension and freshwater discharge bringing additional loads of coloured dissolved organic materials (CDOM). This results in multiple, independently varying, optically significant components, each of which influences the water leaving radiance spectrum making interpretation of spectral changes significantly more difficult. Many studies have demonstrated the breakdown in performance of standard algorithms (e.g. Chl, McKee et al. 2007) in optically complex coastal waters.
In this paper we will focus on the effect of suspended sediment on optical properties of the water column. Suspended sediment has long been known to influence light penetration (Gordon and McCluney, 1975) which can limit primary production and also contribute to hypoxia (Greig et al., 2005). There is interest in monitoring sediment concentration for coastal erosion applications and various OCRS algorithms have been developed that exploit the relatively strong backscattering properties of sediment. For example, Doxaran et al. (2002) successfully presented a sediment algorithm for the highly turbid Gironde estuary. More recently a radiative transfer approach was used to refine this type of approach to incorporate the potential impact of other materials on the red reflectance values that support sediment algorithms (Neil et al., 2011). This algorithm provides estimates of maximum and minimum sediment load concentrations assuming reasonable potential ranges of Chl and CDOM for coastal waters. The aim of this paper is to determine the extent to which the Neil et al. algorithm, which was developed for Irish Sea waters, can be applied to data collected in the North Sea. The ultimate goal is to assess the potential for using OCRS data to monitor suspended sediment concentrations in coastal waters, with monitoring marine turbine arrays an obvious and potentially important application.
In terms of surface area and primary productivity, the global ocean is heavily dominated by deep, oceanic waters, where the optical properties are driven by phytoplankton, associated dissolved organics and water itself. It is little surprise then that early standard OCRS products were developed for optimal performance over these globally significant regions. Standard chlorophyll algorithms were developed using changes in blue-green reflectance ratios (e.g. O’Reilley et al., 1998) that can be related to the effect of changing concentrations of microscopic scale (1µm-200µm) phytoplankton (Kirk,1983) forming blooms that can stretch for thousands of km. More recently, attention has shifted to economically important coastal regions where, for example, harmful algal blooms have potential to cause significant societal and economic impact. OCRS algorithms have been developed to specifically aid in the monitoring of both toxic species e.g. Karenia brevis in the Gulf of Mexico (Stumpf et al., 2003), and also to monitor for extreme eutrophication events where excessive levels of phytoplankton cause the reduction of oxygen dissolved in the water column (hypoxia) leading to animal mortality (e.g. Mallin et al., 2006).
The optically complex nature of coastal waters, more generally, presents a particular problem for OCRS applications in these regions. Shallow shelf seas and other inshore waters are subject to the influence of sediment resuspension and freshwater discharge bringing additional loads of coloured dissolved organic materials (CDOM). This results in multiple, independently varying, optically significant components, each of which influences the water leaving radiance spectrum making interpretation of spectral changes significantly more difficult. Many studies have demonstrated the breakdown in performance of standard algorithms (e.g. Chl, McKee et al. 2007) in optically complex coastal waters.
In this paper we will focus on the effect of suspended sediment on optical properties of the water column. Suspended sediment has long been known to influence light penetration (Gordon and McCluney, 1975) which can limit primary production and also contribute to hypoxia (Greig et al., 2005). There is interest in monitoring sediment concentration for coastal erosion applications and various OCRS algorithms have been developed that exploit the relatively strong backscattering properties of sediment. For example, Doxaran et al. (2002) successfully presented a sediment algorithm for the highly turbid Gironde estuary. More recently a radiative transfer approach was used to refine this type of approach to incorporate the potential impact of other materials on the red reflectance values that support sediment algorithms (Neil et al., 2011). This algorithm provides estimates of maximum and minimum sediment load concentrations assuming reasonable potential ranges of Chl and CDOM for coastal waters. The aim of this paper is to determine the extent to which the Neil et al. algorithm, which was developed for Irish Sea waters, can be applied to data collected in the North Sea. The ultimate goal is to assess the potential for using OCRS data to monitor suspended sediment concentrations in coastal waters, with monitoring marine turbine arrays an obvious and potentially important application.
Original language | English |
---|---|
Title of host publication | TeraWatt Position Papers |
Subtitle of host publication | A 'toolbox' of methods to better understand and assess the effects of tidal and wave energy arrays on the marine environment |
Editors | Jonathan Side |
Place of Publication | St Andrews |
Pages | 129-140 |
Number of pages | 12 |
Publication status | Published - 30 Sept 2015 |
Keywords
- marine renewable energy
- sediments
- satellite applications
Fingerprint
Dive into the research topics of 'Use of ocean colour remote sensing to monitor sea surface suspended sediments'. Together they form a unique fingerprint.Projects
- 1 Finished
-
TeraWatt: Large scale Interactive coupled 3D modelling for wave and tidal energy resource and environmental impact (Remit 1 MASTS Consortium Proposal)
Heath, M. (Principal Investigator) & McKee, D. (Co-investigator)
EPSRC (Engineering and Physical Sciences Research Council)
1/06/12 → 30/11/15
Project: Research
Datasets
-
Vertical profiles of seawater turbdity, chlorophyll temperature and salinity
Heath, M. (Creator), University of Strathclyde, 15 Dec 2015
DOI: 10.15129/ea4d4dbf-9807-4063-a4e2-716a1a6b7f7b
Dataset
Research output
- 3 Article
-
Increasing turbidity in the North Sea during the 20th century due to changing wave climate
Wilson, R. J. & Heath, M. R., 6 Dec 2019, In: Ocean Science. 15, p. 1615–1625 11 p.Research output: Contribution to journal › Article › peer-review
Open AccessFile24 Citations (Scopus)44 Downloads (Pure) -
Developing methodologies for large scale wave and tidal stream marine renewable energy extraction and its environmental impact: an overview of the TeraWatt project
Side, J., Gallego, A., James, M., Davies, I., Heath, M., Karunarathna , H., Venugopal , V., Vögler , A. & Burrows, M., 1 Oct 2017, In: Ocean and Coastal Management. 147, p. 1-5 5 p.Research output: Contribution to journal › Article › peer-review
Open AccessFile5 Citations (Scopus)132 Downloads (Pure) -
Large scale three-dimensional modelling for wave and tidal energy resource and environmental impact: methodologies for quantifying acceptable thresholds for sustainable exploitation
Gallego, A., Side, J., Baston, S., Waldman, S., Bell, M., James, M., Davies, I., O'Hara Murray, R., Heath, M., Sabatino, A., McKee, D., McCaig, C., Karunarathna , H., Fairley, I., Chatzirodou , A., Venugopal , V., Nemalidinne, R., Yung, T. Z., Vögler , A. & MacIver, R. & 1 others, , 1 Oct 2017, In: Ocean and Coastal Management. 147, p. 67-77 11 p.Research output: Contribution to journal › Article › peer-review
Open AccessFile14 Citations (Scopus)119 Downloads (Pure)