The importance of measuring ocean colour
EUMETSAT Remote Sensing Scientist Ewa Kwiatkowska explains Sentinel-3’s role in measuring ocean colour and why this information is so important
Data derived from satellite observations of the Earth’s oceans, their biogeochemistry, water quality and clarity, are critically important to Europe’s “blue economy”, currently worth almost €500 billion a year.
When Sentinel-3A begins providing this information in 2016, information that cannot be obtained from physical measurements, it will be the only European Satellite dedicated to ocean colour in Europe and anticipation amongst users of this data is high.
Sentinel-3A, the first of two identical satellites that will operate in tandem to provide optimum global coverage, is one of a fleet of Earth Observation satellites central to the European Union’s Copernicus Programme.
It will measure ocean colour, sea surface temperature and sea surface height, and provide information about the state of vegetation and the height of rivers and lakes when it passes over land.
"This information is tremendously important for supporting the implementation of European maritime policies"
EUMETSAT Remote Sensing Scientist and ocean colour expert Ewa Kwiatkowska says ocean colour measurements provide information about the biological and biogeochemical activity of aquatic ecosystems.
“This information is tremendously important for supporting the implementation of European maritime policies and achieving the Good Environmental Status of EU marine waters,” Kwiatkowska said.
“There will be Near Real Time applications providing information such as the presence of harmful algal blooms, which are poisonous to aquatic organisms, such as fish, and to humans who eat the poisoned seafood.
“Fisheries and aquaculture are big customers of ocean colour data because they show water chlorophyll concentrations. Chlorophyll concentrations are an indicator of phytoplankton biomass and these phytoplankton are the basis of the marine food chain.”
This information was also important to organisations with an interest in the climate, Earth system variability and carbon cycle, as phytoplankton convert carbon dioxide into oxygen. About half the oxygen we breathe is produced by phytoplankton, Kwiatkowska said.
“The data are also used for monitoring of coastal environments and sediment transport,” she added. “These observations tell us about the water clarity and quality. People don’t like to live next to polluted coastlines.”
Ocean colour was previously measured by the Medium Resolution Imaging Spectrometer carried on the European Space Agency’s (ESA’s) Envisat satellite, which ceased operations in 2012. Currently, the only global ocean colour capability is provided by NASA and NOAA.
"The Ocean and Land Colour Instrument on Sentinel-3 will provide the best ocean colour measurements available globally"
“We definitely need the continuation of these observations,” Kwiatkowska said. “Many users, starting with environmental agencies, fisheries and people interested in marine resources, and finishing on climate, need a long time series of these data to look for trends and anomalies and the Sentinel-3 fleet will provide this information.”
The Ocean and Land Colour Instrument on Sentinel-3 will provide the best ocean colour measurements available globally, in terms of spatial and spectral resolution, for probably the next decade, she said.
EUMETSAT is co-chair, along with ESA, of the Sentinel-3 Validation Team and Kwiatkowska is a co-chair of the team’s Ocean Colour Sub-Group - the largest of the four sub-groups - and comprising members from all continents, except Antarctica.
Her goal is to make the Sentinel-3 mission the best it can be and to make the best possible contribution to the Copernicus Programme and the global ocean colour data user community.
“This will be the first time that EUMETSAT will be processing and disseminating ocean colour data, so it’s a new type of measurement and a steep learning curve for us all here at EUMETSAT,” Kwiatkowska said.
“The challenge is in the way I as a scientist need to cover all aspects of scientific data quality and expression of user needs, starting from making sure that our processors are working well and our algorithms are of good quality, going through data dissemination - that users have access to long-term time series that they need for analyses and applications, finishing on future product evolutions, and making sure that we at EUMETSAT have got the right capabilities to have the best handle on the mission performance and can meet user needs.
“The most rewarding aspect of my involvement in the Sentinel-3 project is the interaction with users. For me, it’s really nice to see that we have got so many users out there looking forward to ocean colour measurements.
“There is a very big and active user community that we need to satisfy, so from this point of view, it’s a challenge, but it’s also very exciting going into this new era.”