ocean sciences – orlando – 2008, 4th of march developing a european ocean colour service...

Ocean Sciences – Orlando – 2008, 4th of March

DEVELOPING A EUROPEAN OCEAN COLOUR SERVICE SUPPORTING WATER QUALITY ASSESSMENT AND

OPERATIONAL OCEANOGRAPHY

Antoine Mangin1, Samantha Lavender2, Odile Hembise1,Nicolas Ganzin3, Philippe Garnesson1

(1) ACRI – France(2) ARGANS Ltd – UK(3) Ifremer - France


Rationale

Demonstration of the best use of ocean colour data(*) has been performed for European water quality monitoring, more specifically relying on two ESA supported projects for:

•Local/regional implementation of the Water Framework Directive on all EU marine member states

•European survey and cyclic reporting on water quality trends

(*) all sensors are welcome (here MERIS, SeaWiFS, MODIS)

ESA service MARCOAST

ESA project GlobColour


Few words

ESA service MARCOASTMARCOAST is the GMES Service Element for Marine Applications. This service streamlines the use of any type of EO for downstream activities in preparation of upcoming EU GMES services.40 partners / 5 main lines of services / more than 100 users

ESA project GlobColour (GC)The aim of the Data User Element GlobColour project is to develop and demonstrate an EO-based service supporting global ocean carbon-cycle research. The GlobColour service provides scientists with a long time-series of consistently calibrated global ocean colour information, according to requirements specified by the global ocean colour user community, as represented by the user group: IOCCG, IOCCP and Met Office/NCOF. The last phase of the project (this year) is to support green operational oceanography deployment.

www.globcolour.info

www.marcoast.com

http://www.globcolour.info/




http://www.marcoast.com/


Objective: To qualify evolution of water quality at level of «water masses » in order to put in force Water Framework Directive i) at member state level then ii) at European level

Indicator of water quality: Stability/variability of surface Chla-a seasonal concentrations

Use of either• merged MERIS/MODIS Chl-a or,• MERIS case 2 waters Chl-athrough the Water Quality Service of Marcoast

Marcoast Service to support Regional monitoring of water quality


Regional monitoring of water quality – Marcoast Service

More specifically there are two missions

Analysis of the relevance of water masses delineation (which is achieved). Check afterwards with Ocean Colour derived information that variability of water composition within each water mass is reasonable in term of range of values.

And then…

Support to the setting up the surveillance: Compare this range of variability to acceptable range allowing the qualification of water mass status and conclusions in term of deployment of complementary in situ observation network.



Water masses ‘a priori’ delineation


Leucate

Barcarès

Bouzigues

Sète

Carteau

Leucate

Barcarès

Bouzigues

Sète

Carteau

Validation – example : Bouzigues

In situcompared toEO derived

Range of spatial variability

•Temporal trends are captured but amplified with MERIS case 2

•Spatial variability is important (possibly due to environmental effects)



Final reporting based on P90 values of Chl-a as agreed by Regional Water Authority in charge of monitoring

Spatial variability

within water

mass +/-

Environmental status ranking

Water masses



Reporting

Water masses delineation appears to be consistent (most of them present a low spatial variability



The reporting is already operational, however some items are still under investigation:

•Effort on validation

•Exploitation of a better spatial resolution (MERIS FR)

•Strategy of merging EO to existing in situ network is under analysis


Context for this monitoing:European Environmental Agency reporting on trends

Today the reporting is based on in situ observation and the metric for trend identification is, for a given area, the number of stations that have shown a significant increase/decrease of observed Chla (*) during the last 10 years.

(*) Observed Chla is an average seasonal value built on a very strict protocol.

Use of GlobColour (GC) Products to support European monitoring of water quality


Background – ingredients for reporting

14 eco-regions

About 6800 Chla samples in 2003-2005

… and thus the report

Works are being undertaken to replace/complement in situ sampling by EO (and here more specifically by GlobColour)


Method used

•Setting up of a non parametric test for detection of trends at GC pixel level.

•The test is based on summation of sign of difference between one status and the previous ones (eg. season 2005 compared to 2004, 2003 etc..)

•Statistical variance 2 of a white noise on such times series is analytically known.

•So … any departure above (resp. below) 2 (resp. –2) from this law would indicate that a trend exist with a 95% significance level

Trends analysis

Important distinction: We are not trying here to quantify trends but to identify the probable ones.


2.5% 2.5%

Trends detection – SeaWiFs – 1998-2006

Spatial consistency of possible trends are evidences of trends

White noise at a level of significance of 95%

http://upload.wikimedia.org/wikipedia/fr/f/ff/Gauss_reduite.png


MODIS SeaWiFS

MERIS GlobColour

Patchiness of MERISresults is probably

due to coverage

Possible trends are very consistent from one single sensor to the other

2003-2006


Correlation coefficient for the seasonal figures

.6/.8/.6

.2/.5/.2

.8/.9/.9

.3/.6/.4

.8/.9/.8

.9/.9/.9.7/.8/.7

.8/.9/.8

.8/.8/.8.9/.9/.8

MERSWF/SWFMOD/MERMOD

.9/.9/.9

This gives a reasonible confidence level (or caution level!) in the merging of all sensors in order to identifiy trends


0% 60% 80%40% 100%20%

2003-2005 trends GC - 1998-2006 trends

Final reporting for EEA

Are well comparable!


Conclusions

ESA’s Marcoast and GlobColour initiatives have been the opportunity to demonstrate reliability of OC for environmental reporting.

Robusts methods have been derived to stick to environmental reporting use and protocols

Providing that the flow of OC data is maintained, this opens the door to a real and operational integrated service for water quality assessment and operational oceanography


DEVELOPING A EUROPEAN OCEAN COLOUR SERVICE SUPPORTING WATER QUALITY ASSESSMENT AND

OPERATIONAL OCEANOGRAPHY

Antoine Mangin1, Samantha Lavender2, Odile Hembise1,Nicolas Ganzin3, Philippe Garnesson1

(1) ACRI – France(2) ARGANS Ltd – UK(3) Ifremer - France

Thank you for attention

ocean sciences – orlando – 2008, 4th of march developing a european ocean colour service...

Documents

ocean sciences orlando

water quality trends

evolution of water quality

level of water masses

regional water authority

globcolour service

delineation slide

eobased service