Remote Sensing of Ocean Color and Water Quality

Remote sensing of ocean colour and water quality uses satellite and airborne sensors to measure the spectral characteristics of sunlight scattered by the water column. By quantifying water-leaving radiance and applying robust atmospheric correction algorithms, practitioners retrieve key water quality parameters such as chlorophyll-a concentration, suspended particulate matter and coloured dissolved organic matter. Advances in sensor design—ranging from multispectral to hyperspectral instruments—have expanded spectral and spatial resolution, enabling the detection of subtle biogeochemical signals across coastal, estuarine and open-ocean environments. Calibration and validation against in situ measurements ensure the reliability of derived products, while the integration of machine-learning approaches and uncertainty quantification has enhanced the accuracy and operational utility of global water quality monitoring. These developments underpin applications in ecosystem assessment, harmful algal bloom forecasting and the management of water resources at regional to planetary scales.

Research from Nature Portfolio

An investigation into the optical signature of oil-in-water emulsions employed Monte Carlo modelling to simulate upwelling and downwelling radiance within the seawater column. The study demonstrated how differential radiance measurements between virtual underwater sensors can be optimised to signal the presence of oil substances, offering a basis for designing specialised sensors for marine pollution monitoring. This work highlights the potential of radiometric modelling in developing next-generation remote sensing tools for rapid detection of hydrocarbon contaminants in diverse aquatic environments.

Remote Sensing of Ocean Color and Water Quality publication trend

The graph below shows the total number of articles in remote sensing of ocean color and water quality across all publications each year (not limited to Nature Index journals).

Technical terms

Water-leaving radiance: The portion of sunlight scattered upward from the water that exits the surface and is measured by remote sensors.

Atmospheric correction: A set of algorithms used to remove the effects of atmospheric scattering and absorption from remotely sensed data.

Remote sensing reflectance (Rrs): The ratio of water-leaving radiance to downwelling irradiance just above the surface, expressed as a function of wavelength.

Chlorophyll-a concentration: A proxy for phytoplankton biomass, derived from the spectral absorption features of chlorophyll in the visible bands.

Hyperspectral sensing: Acquisition of reflected light across hundreds of narrow, contiguous spectral bands, enabling detailed characterisation of water constituents.

Inherent optical properties: Fundamental parameters (absorption and scattering coefficients) that describe how water and its constituents interact with light.

References

1. Radiometric assessment of OLCI, VIIRS, and MODIS using fiducial reference measurements along the Atlantic Meridional Transect. Remote Sensing of Environment (2023).
2. GLORIA - A globally representative hyperspectral in situ dataset for optical sensing of water quality. Scientific Data (2023).
3. Modelling the upwelling radiance detected in a seawater column for oil-in-water emulsion tracking. Scientific Reports (2023).
4. WATERHYPERNET: a prototype network of automated in situ measurements of hyperspectral water reflectance for satellite validation and water quality monitoring. Frontiers in Remote Sensing (2024).