Page 1GlobColour/Medspiration User consultation – November 20-22, 2007, Oslo All rights reserved © 2006, ACRI-ST Full product set validation over coastal

Page 1 GlobColour/Medspiration User consultation – November 20-22, 2007, Oslo

All rights reserved © 2006, ACRI-ST

Full product set validation over coastal Case II waters

Dominique Durand,Are Folkestad, Jo Høkedal,

Kai SørensenNIVA

Samantha LavenderUniv. Plymouth

,



Scope

• The FPS dataset• DDS for coastal case II waters• Validation against in-situ data

– ”global” assessment– Regional and water type approach– Specific results at diagnostic sites

• Relative validation against pre-merged data• 10-year time series• Conclusions



FPS dataset

• 10-year of global observations– SeaWiFS: 1997 - 2006

– MODIS: 2002 - 2006

– MERIS: 2002 - 2006

• Use of an extended in-situ dataset to try to ensure a robust and statistically sounded validation– OBPG, NOMAD, Boussole

– Several coastal DDS



The GlobCOLOURproducts



GlobColour products



The flags



Level-2 Characterisation Chl-a Results

SeaWIFS MODIS/A MERIS

Mean Med Mean Med Mean In-situ Satellite

Product Slope Intcpt r2 Ratio Ratio %Diff %Diff bias RMS Range Range

MER-All Chl 0.90 -0.13 0.90 1.05 0.98 26.50 17.58 -0.01 (*) 0.34 (*) 0.07 3.14 0.07 2.84

MOD-All Chl 0.81 0.05 0.74 1.21 1.14 43.46 46.68 0.09 (*) 0.47 (*) 0.06 3.14 0.07 2.64

SWF-All Chl 0.93 0.07 0.88 1.22 1.08 46.76 37.01 0.07 (*) 0.51 (*) 0.04 13.87 0.03 11.04

Achievement: Statistical uncertainties have been derived and are used for merging



Types of In Situ Data

• Chlorophyll (HPLC and in-vitro fluorometric)• Fully normalised water-leaving radiance primarily

at 412, 443, 490, 510, 531, 555, 620, 670 nm– Computed when Lw, Ed, Es, Chl, and solar and

viewing geometry available.• Diffuse attenuation coefficient at ~490nm • Dissolved Coloured Organic Material



Identification of Case 2 Validation Sites

• Selection of sites for Case 2 validation based on general knowledge



A priori DDS for coastal Case 2 waters

• Venice Tower (Adriatic Sea)• Sopot (Poland)• Helgoland (Germany)• Skagerrak (NIVA-Ferrybox)• Helsinki Light House (Gulf of

Finland)• Gustav Dahlén Tower (Baltic

Sea)

• CALCOFI (California)• Gulf of Maine (USA Canada)• MVCO (Rhode Island,

Chesapeake Bay)• COVE

• Benguela (South Africa)

DDS used for validation of coastal case 2 waters



Identification of Case 2, subclassification

• Selection of sites for Case 2 validation based on general knowledge

• Identification of Case 2-S using the EL555 product

• Case 2-Y flag is not active yet in MERIS RR products



“Excess radiance” at 555 nm(turbid Case 2 waters)



Number of match-ups per validation site

VeniceTower

Gustav DalenTower

HelsinkiLightHouse

Chesap.Bay

RhodeIsland

NIVA FerryBSkagerrak Global

Chl hplc 8 - - - - 90 98

Chl fluor 2736 239 282 262 1237 - 4756

GSM Kd490 3 - - 19 3 - 25

CDM - - - 15 2 - 17

Chl hplc 8 - - - - 157 165

Chl fluor 2952 301 307 332 1305 - 5197

L412 3023 285 250 302 1315 9 5184

AVW L443 3024 314 347 334 1319 9 5347

L490 42 136 347 334 453 9 1321

L510 9 - - 4 2 9 24

L555 2781 239 281 279 1234 4 4818

L670 584 313 347 317 1317 9 2887



r2 0.35RMS 0.36

BIAS 0.13SLOPE 0.62

OFFSET 0.10

r2 0.57RMS 0.31

BIAS 0.01SLOPE 0.69

OFFSET 0.23

r2 0.72RMS 0.27

BIAS -0.01SLOPE 0.72

OFFSET 0.20

r2 0.40RMS 0.46


OFFSET 0.41

r2 0.55RMS 0.09

BIAS 0.02SLOPE 0.73

OFFSET 0.03

Validation of nLw over coastal case II waters



r2 0.29RMS 0.92BIAS 0.02

SLOPE 0.38OFFSET 0.94

r2 0.22RMS 1.33BIAS 0.88


r2 0.29RMS 1.12


OFFSET 0.69

r2 0.63RMS 0.81BIAS 0.48


Validation of Chl products over coastal case II waters



Validation of CHL in turbid/ non-turbid coastal waters

r2 0.42RMS 0.55


OFFSET 1.06

r2 0.27RMS 1.09BIAS 0.11


r2 0.21RMS 1.89BIAS 1.35


r2 0.24RMS 0.55BIAS 0.39




Chlorophyll : regional analysis



Regional validation of CHL

N 520r2 0.01

RMS 1.54BIAS 1.09


N 1497r2 0.07

RMS 1.30BIAS 1.07


Helsinki LighthouseG. Dalen Tower

Chesapeake BayRhode Island



Relative validation against pre-merged data (Global)



Performance of the GlobCOLOUR products in case 2 waters: CHL – July 2002

All pixels

Turbid flagTurbid flag<200m

Depth < 200m



Performance of the GlobCOLOUR products in case 2 waters: CDM – July 2002

All pixels


Depth < 200m



Performance of the GlobCOLOUR products in case 2 waters: bbp – July 2002

All pixels


Depth < 200m



10-years time series



NIVA-FerryBox CHL monthly mean



Conclusions• Validation of merged case I products in coastal case II waters presents the

same limitations than with non-merged products• Validation of daily-averaged products over variable coastal waters is a

challenging task– Spatial discrepancy (4.6 km vs. point)– Temporal discrepancy (daily average vs. instantaneous)

• Discriminate between algorithm weakness and quality of the in-situ dataset has shown to be difficult

• A better in-situ dataset for coastal case 2 waters is needed – best results so far from Ferrybox data collection

• GlobColour GSM01 merging algorithm shows to be quite robust over coastal waters (tested so far)

• GlobColour merged products show a potential for investigating seasonal to inter-annual variability in coastal zone: One of the GlobColour follow-up?

• In coastal waters with inherent high optical variability, the use the various OC data sources independently remains an asset for resolving temporal and spatial variability



Thank youfor yourattention

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Page 1GlobColour/Medspiration User consultation – November 20-22, 2007, Oslo All rights reserved © 2006, ACRI-ST Full product set validation over coastal