Satellite-based monitoring and the Ocean Colour Observations

F. GohinF. Gohin

Ifremer Ifremer DYNECO/PELAGOS, Brest, BrittanyDYNECO/PELAGOS, Brest, Brittany

Workshop MOMAR, Livorno, 18-19 April 2012

Satellite and in situ data used at Ifremer for the surveillance

of the coastal environment

SATELLITE

INFRA-RED

Sea Surface Température

Résolution 1-2 km

AVHRR, SEVIRI/MSG

SATELLITEOCEAN COLOUR

Chl-a, Non-algal SuspendedParticulate Matters, Turbidity

SeaWiFS, MODIS, MERIS

Résolution 1.1 km

IN SITU

Sea Surface Temperature, Chl-a, Fluorescence, Turbidity, SPM

- REPHY/Ifremer &SOMLIT/CNRS networks

- MAREL instrumented stations

Validation of the sedimentaryand ecological models

Forcing the light in primaryproductivity models

Water Framework Directive Marine Strategy Directive Coastal Operational Oceanography(Previmer project)

Mineral

SPM

First fortnight of February

The area processed daily at Ifremer for the GMES/MyOcean project. In MyOcean2 OC TAC,

leader CNR, Ifremer will be in charge of the new wide “Atlantic” area with PML (Plymouth) and ACRI-ST.

Chlorophyll

First fortnight

of June

Mineral Suspended

Particulate Matters

First fortnight

of February

Chl-a April 1st 2012 Mineral SPM (including coccoliths)

Daily Multi-Sensor products (MERIS/MODIS)

Ferry data, courtesy of Mohammed Qurban, NOC of Southampton

Karenia mikimotoi bloom: Satellite&in situ composite 8th to 11th July 2003

Multi-source map (serveur http:/www.ifremer.fr/nausicaa/marcoast/index.htm

The MAREL automatic station in the northern English Channel (Boulogne harbour)

Multi-source graphs extracted from the WEB serveur httwww.ifremer.fr/nausicaa/marcoast/index.htm

Exemple: Annual Time Series

of Chl-a derived from in-situ

fluorescence, MERIS and

MODIS

October 2010-2011

In-situ mean cycle and percentile

90 are indicated on the graph

Statistics derived from satellite data

1) Mean Annual Cycles of Chlorophyll-a, mineral SPM andTurbidity (in NTU)

3) Percentile 90 of the Chlorophyll-a concentration for the WaterFramework Directive and the Marine Strategy Directive

2) Statistical modelling of SPM as a function of tide and waves

Seasonal evolution of chlorophyll (SeaWiFS+MODIS 1998-2007)

1998-2007

Seasonal evolution of Mineral SPM

Validation of the satellite products by comparison to coastalin-situ data provided by REPHY/Ifremer et SOMLIT/CNRS

networks

3 environmental parameters are compared:

Chl-a, SPM and Turbidity

28 stations sélectionnées

Exemple of Validation : The cross-shore transect off Boulogne

CHL MODIS/SITU Point 1 Point 2 Point 3

Turb MODIS/SITU Point 1 Point 2 Point 3

Côte Largees in situ et satellite utilisés de 2003 à 2009Gohin, F.: Annual cycles of chlorophyll-a, non-algal suspended particulate matter,

and turbidity observed from space and in-situ in coastal waters, Ocean Sci., 7,

705-732, doi:10.5194/os-7-705-2011, 2011.

http://www.ocean-sci.net/7/705/2011/

Application WFD: P90 Chl-a satellite vs P90 Chl-a insitu for the productive period

Here the percentile 90 of Chl-a for the Bay of Biscay

A unique source of information for the European Marine Strategy Directive

A unique source of information for the European Marine Strategy Directive

Here the percentile 90 of Chl-a for the Mediterranean Sea (Thanks to Nicolas Ganzin)

Relationship between major meteorological events

and OC products

Exemple 1 : SPM variability has been evaluated using a simple statistical model from tide

Effect of the tidal cycle

SPM = αααα*SPMMean*C(tide)β β β β (1)(1)(1)(1) SPMMean is the Mean seasonal SPM

αααα and ββββ are estimated after log-transformation of SPM (linear regression in log)

R2 is an

r2 regression coefficient

SPM Variability during a spring-neap tidal cycle

March

Exemple 2: SPM variability has been evaluated using a simple statistical model from

tide, waves and Chl-a

Effect of Chl-a is added for aggregation and stratificationSPM = α α α α (Tide)β β β β * (HS)γγγγ * (1/1+Chl-a)d (2)2)2)2)

αααα and ββββ are estimated after log-transformation of SPM (linear regression in log)

Observed SPM is obtained from MERIS/MODIS interpolated maps

Rivier, A., Gohin, F., Bryère, P., Petus, C., Guillou, N., and Chapalain, G.,. Observed vs.

predicted variability in non-algal suspended particulate matter concentration in the English

Channel in relation to tides and waves. Geo-Marine Letters, 32, 2, 139-151, doi:10.1007/s00367-

011-0271, 2012.

r2 regression coefficient

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Exemple 3 : Chl-a variability in spring and summer in relation to river outflows

Perspectives

1) The Previmer system will be extended to the English Channel and the

Mediterranean Sea. New products will be proposed for promotion through

bulletin (Karenai mikimotoi alert in the English Channel, high level of Chl-a, …)

2) A common product will be proposed by PML, ACRI-ST and Ifremer for a

new and larger MyOcean Atlantic region within the Ocean Colour TAC

3) Comparisons to hydro-sedimentary and ecological models will be

carried out but purely statistical models, based on merged MODIS/MERIS

products, in response to meteorological forcings will be proposed.

Present difficulties in acess to Ocean Colour data can be used as an

opportunity to enhance analyses of the long MERIS/MODIS/SeaWiFS time

series, waiting for Sentinel-3 and the VIIRS