towards an integrated sst and ocean color dataset for coastal applications at ifremer
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Towards an integrated SST and Ocean Color dataset for coastal applications at Ifremer. Bertrand Saulquin & Francis Gohin. Introduction For the coastal environmental monitoring, different parameters such as the - PowerPoint PPT PresentationTRANSCRIPT
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Towards an integrated SST and Ocean Color datasetfor coastal applications at Ifremer
Bertrand Saulquin & Francis Gohin
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Introduction
For the coastal environmental monitoring, different parameters such as the temperature, chlorophyll-a, turbidity are measured regularly on the French coasts since 1984. The application of the new Water Framework Directive (WFD), based on these data, tends to increase the number of stations.
At the moment satellite data are not systematically used on coastal area. This come from historical problems in the satellite data such as atmospheric corrections (ocean colour), land effects (all sensors) … that led to some lacks in the data on the shores or some problems on the quality of the retrievements. The developpement of regional or dedicated algorithms, associated with the increasing resolution of the sensors, tends to increase the reliability of the satellite in these areas.
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ChlorophyllTurbidity
SST
3 Parameters available in situ and from R/S techniques
One of Ifremer’s objectives is to compare systematically time series of in situ data and satellite data for these parameters at some selected stations. These comparisons will be freely accessible using Web servers such as NAUSICAA and will allow us to validate our global and regional products (SST and Color) and help also our users to evaluate satellite data and in situ data compared to an average situation.
Actions supported by :MARCOAST (GMES-Service Element, ESA funded)
ECOOP (European Coastal sea Operational Observing and Forecasting System , FP6)
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Operational satellite products available at Ifremer, mean OC5 Chl-a and turbidity for October 2007.
TurbidityChl-a
Turbidity, Modis, computed with Ifremer regional algorithm.
Chl-a, Modis, computed with Ifremer regional algorithm. Also available SPM, Kpar, secchi depth, radiances… and Meris case1 and case2.
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Medspiration product: NOAA 18, NAR SST
Merged SST products available at Ifremer:
-Global Scale:-ODYSSEA Mersea Product.
Operational satellite products available at Ifremer, mean SST of October 2007.
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The Ocean Color satellite / in situ experience at Ifremer for coastal waters.
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More than 300 stations along the French coasts.
-Regular measurements of temperature, chlorophyll, turbidity, salinity, oxygen on all stations.-Phytoplankton determination and toxicity measurments at some of the stations.
REPHY: Phytoplankton and Phycotoxins Monitoring Network
The network is actually in an updating phase, with some displacements of existing stations regarding the representativeness in the water body, and the creation of new stations.
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These coastal in situ data are the base for the coastal environmental policies
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A privileged link has been established between the in situ
networks and the Dyneco/LOS departments at Ifremer for the Water Framework Directive.
National in situ networks
REPHY: phytoplankton & hydrology / Ifremer
SOMLIT: hydrology / CNRS-INSU
Regional Chl-a algorithm validation at the network stations
Boulogne point 2, SeaWIFS OC5 vs In situ 1999-2004
Boulogne point 2, MODIS OC5 vs In situ 2003-2005
Cabourg, SeaWIFS OC5 vs In situ 1999-2004
Cabourg, MODIS OC5 vs In situ 2003-2005
Regional Chl-a algorithm validation at the network stations
Cancale, SeaWIFS OC5 vs In situ 1999-2004
Cancale, MODIS OC5 vs In situ 2003-2005
Regional Chl-a algorithm validation at the network stations
Other validation plots and publication available on demand.
nm
nm
nm
nm
A1221
WestG
Oyster
NorthDogger
8°E
8°E
7°E
7°E
6°E
6°E
5°E
5°E
4°E
4°E
3°E
3°E
2°E
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56°N 56°N
55°N 55°N
54°N 54°N
53°N 53°N
52°N 52°N
EMECO -North Sea Ecosystem Observatory
Legend
FerryData_GKSS_DE
Fluor_Turner
0-5
5-10
10-15
15-20
20-25
chlorophyll_a_20070411.tif
Value
High : 10
Low : 0
The latest image 5 days before departure of the CEFAS cruise (11th April 2007) shows events in the eastern North Sea in detail. The Oyster Ground SmartBuoy site is now located on the edge of a bloom, as shown by the increase in chlorophyll fluorescence on the 9th April (trace below). Combined use of GKSS ferry data and Ifremer remote sensing shows in detail the position of a large bloom north of the Dutch-German border (extract from Report CEFAS n°4)
A future application for the satellite colour data in coastal area, the WFD directive?
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The SST experience at Ifremer for coastal waters.
Objectives:
-Determination of the average situations and trends.-Building an historical interpolated SST data set since 1986. -Provide some comparisons with the historical and real time coastal in situ data.
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The average SST(x,t) and trends have been modelled from AVHRR/Pathfinder
and coastal stations in situ data (longer series than for ocean color).
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ROSCOFF 89.6% of the variance explained by 2 harmonics
FLAMANVILLE 95.2% of variance explained by 2 harmonics
The temporal model for the average SST(x,t).
Parameters P0 and P1 calculated from AVHRR data (1986-2006)
P1, warming slopeP0, average SST 1986
SST(t)= P0+P1*t - P2*cos[2pi/365(t-P3)]-P4*cos[2pi/182.5(t-P5)]
P2, half amplitude of the first harmonic P3, phase of the first harmonic
SST(t)= P0+P1*t- P2*cos[2pi/365(t-P3)]-P4*cos[2pi/182.5(t-P5)]
Parameters P2 and P3
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Evaluation of the SST model over the périod 1986-2006
Standard deviation satellite SST / model
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The model is used in the kriging procedure of the AVHRR data (1986-2006) and
the Medpiration products (NAR) since the beginning of 2006. Example of kriging of a daily SST image (Medspiration NAR 18, 2007/11/07).
Time interval for the OI [-4days ,+4days]
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Resulting SST images for the NAR 18 image of the 07/11/2007
Kriged SST AnomalyDaily anomaly
Daily SST Recomposed SST
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Comparison between the SST model and a daily image, sample
of the NAR 18 for the 08/11/2007
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Validation of the satellite interpolated SST on the in situ observations at coastal stations
Station of Wimereux.
1997-2006
Offshore to coastal temperaturemodel.
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Satellite SST Kriged satellite SST
Station
(sampling during the day)
Nb match-ups
BiasSat-Situ
St. dev. Sat-Situ
Nb match-ups BiasSat-Situ
St. devSat- Situ
Wimereux1998-2006
20 -0.47 0.43 105 -0.29 0.44
Boulogne 1998-2006
16 -0.2 0.78 103 -0.43 0.98
Roscoff2002-2005
3 -0.34 1.23 45 -0.1 0.49
Dunkerque1998-2006
12 -0.23 0.57 57 -0.32 0.64
Statistical results, comparisons of kriged SST with in situ data.Satellite SST Kriged satellite SST
Station Nb match-ups
BiasSat-Situ
St. dev.Sat-Situ
Nb match-ups BiasSat-Situ
St. dev.Sat-Situ
Profiles data1986-2006
11 -0.47 0.92 50 -0.39 0.84
Thermo-salinograph data1986-2006
916 -0.23 0.51 5717 -0.17 0.51
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Towards the integrated SST, Chl, Turbidity approach for coastal
monitoring.
A way to increase the user’s community is to show automatically the comparison of real time data at the stations: a difficult exercice.
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The solid line when available represent the mean in situ calculated over the period 1998-2005 and the dotted line the percentile 90.
POINT_3_Boulogne 2003
SST model
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The solid line when available represent the mean in situ calculated over the period 1998-2005 and the dotted line the percentile 90.
POINT_3_Boulogne 2005
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Cabourg 2003
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Cabourg 2005
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Conclusions
3 parameters, SST, Chl, Turbidity, are available in situ and by R/S for the monitoring of coastal waters for the WFD and in the spirit of GMES.
Daily graphs of SST, Chlorophyll, Turbidity, observations, historical average and Percentile 90, will be available at local stations through Nausicaa. Model outputs will be added to the graphs.
Historical SST data are provided by the AVHRR Pathfinder whose data has proven to be reliable even in the coastal waters of the English Channel. Real time SST will be provided through Medspiration.
We must develop the interactions with the user community concerned by the coastal waters satellite data.
Contact: [email protected] http://www.ifremer.fr/nausicaa/marcoast/index.htm
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illustration of the warming for the English channel
since 1933.
Mean SST derived from the model
for years 1986 and 2006.