Prof. Heidi Dierssen
Department of Marine Sciences,
University of Connecticut,
Groton, CT, USA 06340
Established: June 2020
Benthic reflectance is a measurement describing the color of the seafloor, and is an essential parameter for mapping marine habitats in optically shallow water using remote sensing techniques. It is quantified as the upwelled irradiance reflected from the seafloor normalized to the incident downwelling irradiance. Benthic reflectance has relevance in remote sensing methods for assessing shallow-water bathymetry and benthic habitats. Methods generally involve inversion of the remote-sensing reflectance profile to simultaneously fit both the inherent optical properties of the water column and the bottom spectral reflectance profile. Hyperspectral data, which provide near-continuous spectral measurements across near-ultraviolet, visible, and near infrared wavelengths, offers the best results for discrimination of benthic habitats and specific benthic types such as corals, algae and sand.
There are many different instruments and techniques for making benthic reflectance measurements but no recommendations for the best practices for each method or potential uncertainties inherent to the measurement. Various instruments are used e.g., closed path with internal lighting, open path using natural sunlight, laboratory methods in air etc.
Recent modeling work shows that the three-dimensionality influences the benthic reflectance from shadowing in a manner that is related to the rugosity of the benthic structure (Hedley et al. 2018). Assessing the structure of the coral and solar conditions during fieldwork may provide important information in assessing the variability in benthic reflectance across a habitat and the uncertainty in remote sensing methods to estimate benthic reflectance.
The intent of this working group is to:
- document how these different methods work
- characterize the uncertainties inherent to the measurements
- provide recommendations as to best practices for each method in order to minimize the uncertainty.
- provide recommendations for relevant metadata to be included for each dataset
- possibly recommend practices in field validation for benthic remote sensing.
Working Group Members
Membership of the working group will be international. If you have experience with making benthic reflectance measurements and are interested in contributing your expertise to an IOCCG report on this topic, please contact Heidi Dierssen (firstname.lastname@example.org).