Scientists often use optical measurements of mineral particles suspended in the water column to gather information about aquatic ecosystems. These data have applications in broader society such as assessing ecosystem health, monitoring environmental impacts, and validating numerical ecosystem models. In offshore waters, however, it’s difficult to collect such optical information, especially during winter, when the concentrations may be much higher.
To evaluate the potential for using satellites to measure the particles’ optical properties, Mitchell et al. developed a sequence of algorithms and applied it to 8 years of Moderate Resolution Imaging Spectroradiometer (MODIS) ocean color data. Using these algorithms, the team was able to discern complex patterns across time and space in the mineral particles suspended in the Irish Sea, the body of water nestled between Ireland and Great Britain.
The results show that during the autumn and winter, when the Irish Sea is stirred by a combination of wind and tides, the concentrations of suspended mineral particles are relatively high and peak in the center of the region. By late spring, however, the northern and southern portions of the sea become thermally stratified, and the data indicate a decrease in the concentrations of mineral particles in the surface layer that coincides with the onset of the spring phytoplankton bloom.
Although the authors advise that caution is required in extrapolating the values of the optical properties obtained for the Irish Sea to other regions and that more work must be done to reduce uncertainties and separate out the effects of errors in the MODIS data, this case study suggests it is now feasible to use remote sensing data to study the optical properties of suspended mineral particles in offshore waters, even in cloudy areas. (Journal of Geophysical Research: Oceans, doi:10.1002/2015JC011056, 2016)
—Terri Cook, Freelance Writer
Citation: Cook, T. (2016), Satellites reveal dynamics of suspended mineral particles, Eos, 97, doi:10.1029/2016EO046229. Published on 18 February 2016.