Round Robin

Reasonable convergence has been achieved in the ocean colour community regarding the optimal method for retrieval of chlorophyll a concentration in open ocean waters (International Ocean Colour Coordinating Group (IOCCG 1998) and an algorithm round robin for such algorithms is reported by O'Reilly, Maritorena et al. (1998).

For coastal waters the situation is very much more challenging because of the greater number of degrees of freedom of the underlying scientific problem - typically spectral reflectance is considered to be a function of 3 or more independent components such as chlorophyll a concentration, coloured dissolved organic matter absorption coefficient and non-algae particle concentration (Sathyendranath, Prieur and Morel 1989).
Moreover, conversion from optical properties, such as phytoplankton absorption coefficient, to biogeochemical variables, such as chlorophyll a concentration, may be highly variable in space and time (Bricaud, Babin et al. 1995).
Finally the range of output parameters desired by users for coastal waters is large.

As a consequence a wide range of algorithms have been developed within the international community for Case 2 waters and there is no clear consensus on what algorithm should be applied in what circumstances.
The CoastColour Multi-Sensor RoundRobin task will provide a forum for improving the community's understanding of the performance of the various algorithms and for helping to select the optimal algorithm for a given region and application. A beneficial side effect of the Multi-Sensor RoundRobin task will be to increase the interest in MERIS data and algorithms of the many scientific users for the various AOIs by their inclusion in the preparation of algorithms and analysis of results.

Procedure

The Round Robin Data package will comprise CoastColour Level 1P (TOA radiances), L2 (water leaving radiance reflectances) from MERIS measurements as well as simulated and in situ reflectance data. This data package will be distributed to interested parties together with a protocol for data usage. Scientists will run their Case 2 algorithm (starting from either L1P or L2) and generating IOPs and/or concentrations. The results will be submitted back to the CoastColour team, where a comparison of these local algorithms with the CoastColour products and the standard MERIS products will be made.

The Round Robinn Data Package is available for interested parties. It was accessible via anonymous login until end of October 2011, but now we want to kindly ask you to request account data by sending us a message.

Benefit for participants

Participants to the CoastColour Round Robin will obtain insight into the CoastColour products at an early stage. They will get a detailed report on the comparison of the water products derived with their algorithm with CoastColour products.

Participants will become co-author of the final Round Robin report. It is planned to submit a synthesised version of the report for publication in a peer reviewed journal.

Schedule

• October 2010: Round Robin Protocol available
• November 2010: Round Robin Data Package Part 1 (simulated, images) available, Invitation to participate
• April 2011, 28-29: CCRR algorithm workshop held in Brussels
• April 2011: Round Robin Data package Part 2 (matchups, in situ reflectances)
• July 2011, 20: CCRR algorithm webmeeting
• September 2011: Deadline for submitting algorithm results
• October 2011, 21: CCRR algorithm workshop II, Lisbon (after UCM)
• October 2011: Round Robin draft report
• December 2011: Round Robin Final report and publication