Title: On the temporal consistency of chlorophyll products derived from three ocean-colour sensors
Authors: BREWIN RobertMELIN FredericSATHYENDRANATH ShubhaSTEINMETZ FrancoisCHUPRIN AndreiGRANT M.
Citation: ISPRS JOURNAL OF PHOTOGRAMMETRY AND REMOTE SENSING vol. 97 p. 171-184
Publisher: ELSEVIER SCIENCE BV
Publication Year: 2014
JRC N°: JRC90225
ISSN: 0924-2716
URI: http://www.sciencedirect.com/science/article/pii/S0924271614002196
http://publications.jrc.ec.europa.eu/repository/handle/JRC90225
DOI: 10.1016/j.isprsjprs.2014.08.013
Type: Articles in periodicals and books
Abstract: Satellite ocean-colour sensors have life spans lasting typically five-to-ten years. Detection of long-term trends in chlorophyll-a concentration (Chl-a) using satellite ocean colour thus requires the combination of different ocean-colour missions with sufficient overlap to allow for cross-calibration. A further requirement is that the different sensors perform at a sufficient standard to capture seasonal and inter-annual fluctuations in ocean colour. For over eight years, between July 2002 and December 2010, the SeaWiFS, MODIS-Aqua and MERIS ocean colour sensors operated in parallel. In this paper, we evaluate the temporal consistency in the monthly Chl-a time-series and in monthly inter-annual variations in Chl-a among these three sensors over the 2002-2010 time period. By subsampling the monthly Chl-a data from the three sensors consistently, we found that the Chl-a time-series and Chl-a anomalies among sensors were significantly correlated for >90% of the global ocean.These correlations were also relatively insensitive to the choice of three Chl-a algorithms and two atmospheric correction algorithms. Furthermore, on the subsampled time-series, correlations between Chl-a and time, and correlations between Chl-a and physical variables (sea-surface temperature and sea-surface height) were not significantly different for >92% of the global ocean. The correlations in Chl-a and physical variables observed for all three sensors also reflected previous theories on coupling between physical processes and phytoplankton biomass. The results support the combining of Chl-a data from SeaWiFS, MODIS-Aqua and MERIS sensors, for use in long-term Chl-a trend analysis, and highlight the importance of accounting for differences in spatial sampling among sensors when combining ocean-colour observations.
JRC Directorate:Sustainable Resources

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