|Obtaining high quality ocean colour products at high temporal frequency by exploiting the synergy between polar-orbiting and geostationary sensors|
Vanhellemont, Q.; Neukermans, G.; Ruddick, K. (2012). Obtaining high quality ocean colour products at high temporal frequency by exploiting the synergy between polar-orbiting and geostationary sensors, in: 44th international Liège colloquium on ocean dynamics "Remote sensing of colour, temperature and salinity – new challenges and opportunities" - May 7-11, 2012. pp. 1
In: (2012). 44th international Liège colloquium on ocean dynamics "Remote sensing of colour, temperature and salinity – new challenges and opportunities" - May 7-11, 2012. GHER, Université de Liège: Liège. 126 pp., more
Polar-orbiting ocean colour sensors such as SeaWiFS, MODIS, and MERIS have been covering the world’s oceans for over a decade with a revisit time of 1 to 2 days. This temporal resolution is insufficient to capture the diurnal cycles of biogeochemical processes occurring in open ocean and coastal waters, especially not in regions where cloud cover reduces data availability. Imagery from geostationary platforms can be obtained with a much higher frequency (typically every 15 or 60 minutes), and thus, in theory, can be useful to study those processes. The first ocean colour sensor on a geostationary platform, the Geostationary Ocean Colour Imager (GOCI), was launched in 2009 and in mid 2010, it started collecting hourly data for Northeast Asia. There are no geostationary ocean colour sensors over Europe yet, but, for the turbid waters of the southern North Sea, suspended particulate matter, turbidity, and vertical light attenuation products have recently become available every 15 minutes, by using the SEVIRI meteorological sensor (Neukermans et al., 2009). However, the spatial and spectral resolution of SEVIRI is limited and the calibration and atmospheric correction are less established than those of polar-orbiting sensors. This study investigates the potential of combining the higher spatial and spectral resolution and better atmospheric correction of polar-orbiters, with the higher frequency of SEVIRI in two ways. First, to obtain high frequency and high quality suspended matter, turbidity, and vertical light attenuation products, the data from polar-orbiters are modulated by the variability detected by SEVIRI. Second, SEVIRI vertical light attenuation products are refined using coloured dissolved organic matter and Chl a concentration data from polar-orbiters. Effects of the synergy are investigated using in situ data obtained from moored buoys. Additionally, moving beyond Europe, imagery from GOCI, with much better spectral, spatial and radiometric resolution than SEVIRI, is cross-correlated with MODIS imagery for selected turbid water regions.