Optical in situ and geostationary satellite-borne observations of suspended particles in coastal waters Griet Neukermans 1,2 Promoter: Hubert Loisel 2 Co-promoter: Kevin Ruddick 1 1 Management Unit of the North Sea Mathematical Models, Royal Belgian Institute for Natural Sciences, Brussels, Belgium 2 Universite du Littoral Côte d’Opale, Laboratoire d’Océanologie et de Géosciences, Wimereux, France

Suspended particulate matter (SPM) =material retained on a filter via filtration of seawater =living and non-living particles > ~0.4  m 0.1 mm 1 mm 0.1 mm [SPM] mg L -1 Phytoplankton and zooplankton Detritus and sediments Abundant in SNS Highly dynamic due to tides and winds Strongly related to turbidity (T) and in-water availability of sunlight

Monitoring SPM with optical sensors From space In situ Ocean colour sensors Large spatial coverage Limited temporal coverage (e.g. SNS: 1-2 scenes/day) Continuous measurement Limited spatial coverage Source: Boss et al. (2003) Insufficient to capture high dynamics of SPM!

Geostationary (SEVIRI) No colour low spectral resolution Low spatial resolution (3km) Low sensitivity (designed to look at clouds and ice) 1/3 globe covered every 15 minutes 36000km 800km SEVIRI European Meteorological sensor Polar-orbiting Ocean colour satellites (e.g. MODIS) high spectral resolution high spatial resolution (300m) Global coverage every 2 days SNS: 1-2 scenes per day Source of [Chl a] and [SPM] since 1980’s Satellite orbits

Can SEVIRI be used to detect the high spatio- temporal dynamics of [SPM] in the SNS? 1.Can we get a marine signal from SEVIRI? removal of atmospheric signal - uncertainty? 2.How does the marine signal relate to [SPM], T? uncertainty? 3.Does SEVIRI detect the high temporal dynamics of [SPM] and T? ? Get marine signal from SEVIRI Marine signal → [SPM], T Compare satellite data to in-situ Source: Boss et al. (2003)

SEVIRI vs. MODIS marine signal 8 March 2009, 13h UTC 6 May 2008, 13h UTC SEVIRI MODIS Highest (>100%) uncertainties in clearest waters due to sensor digitization High (>20%) uncertainties in most turbid waters due to atmospheric correction Best detection range: 0.004< <0.08 = 1 mg L -1 <[SPM]< 35 mg L -1 = 1 FNU<T< 35 FNU

in situ T data: SmartBuoys Mills et al. (2003) in situ T every 30 minutes T TH1 WG D T (FNU) on 11 February 2008, 12:00 h UTC Get marine signal from SEVIRI Marine signal → [SPM], T Compare satellite data to in-situ

Diurnal variability of T Get marine signal from SEVIRI Marine signal → [SPM], T Compare satellite data to in-situ SEVIRI Buoy SEVIRI Buoy MODIS

Diurnal variability of T Get marine signal from SEVIRI Marine signal → [SPM], T Compare satellite data to in-situ SEVIRI Buoy SEVIRI Buoy MODIS

SEVIRI daily composite of 34 images Quasi cloudfree MODIS: 1 image 60% clouded remotely sensed ( ) vs. in-situ (, ) diurnal variability of turbidity t(T max ) t( ) Get marine signal from SEVIRI Marine signal → [SPM], T Compare satellite data to in-situ SEVIRI Buoy SEVIRI Buoy MODIS

SEVIRI MSG MSU Electro GOCI COMS Where else can this work?

This thesis was funded by the Belgian Science Policy Office (BELSPO) STEREO Programme in the framework of the BELCOLOUR2 and GEOCOLOUR projects. This work was also supported by Centre National d’Etude Spatiale (CNES) in the frame of the COULCOT project (TOSCA program).

List of peer review publications Neukermans G., K. Ruddick, H. Loisel, and P. Roose, Optimization and quality control of suspended particulate matter concentration measurement using turbidity measurements. Limnology and Oceanography Methods (10): 1011–1023. DOI: /lom Ruddick, K., Q. Vanhellemont, J. Yan, G. Neukermans, G. Wei, and S. Shang, Variability of suspended particulate matter in the Bohai Sea from the Geostationary Ocean Imager (GOCI). Ocean Sciences Journal, 47(3). Neukermans G., K. Ruddick and N. Greenwood. Diurnal variability of turbidity and light attenuation in the southern North Sea from the SEVIRI geostationary sensor. Remote Sensing of Environment, 124: 564–580. doi: /j.rse Neukermans G., Loisel H., Mériaux X., Astoreca R. & McKee D., In situ variability of mass- specific beam attenuation and backscattering of marine particles with respect to particle size, density, and composition. Limnology and Oceanography (57): 124–144. DOI: doi: /lo Vantrepotte V., H. Loisel, X. Mériaux, G. Neukermans, D. Dessailly, C. Jamet, E. Gensac, and A. Gardel, Seasonal and inter-annual ( ) variability of the suspended particulate matter as retrieved from satellite ocean color sensor over the French Guiana coastal waters. Journal of Coastal Research (in press). Nechad B., Ruddick, K.G. and G. Neukermans, Calibration and validation of a generic multisensor algorithm for mapping of turbidity in coastal waters. Proceedings of SPIE "Remote Sensing of the Ocean, Sea Ice, and Large Water Regions" Conference held in Berlin (Germany), 31 August Proc. SPIE Vol. 7473, 74730H. Neukermans G., K. Ruddick, E. Bernard, D. Ramon, B. Nechad and P.Y. Deschamps, Mapping Total Suspended Matter from geostationary satellites: a feasibility study with SEVIRI in the Southern North Sea. Optics Express, 17(16): Get marine signal from SEVIRI Marine signal → [SPM], T Compare satellite data to in-situ