Quantification of mineral particles from remote sensing. Using of spectroradiometric measurements and WASI simulations Results obtained by V. Lafon, C. Giry, N. Bonneton, D. Doxaran, D. Bru C. Petus, M. Schmeltz and J-M Froidefond 1) Spectroradiometric measurements 2) Examples of SPMC quantification in the Bay of Biscay, the French Guiana and the Congo coastal waters 3) Inversion of spectra from the WASI code (P. Gege)
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Quantification of mineral particles from remote sensing ... · Quantification of mineral particles from remote sensing. Using of spectroradiometric measurements and WASI simulations
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Quantification of mineral particles from remote sensing.Using of spectroradiometric measurements and WASI
simulations
Results obtained by V. Lafon, C. Giry, N. Bonneton, D. Doxaran, D. Bru C. Petus, M. Schmeltz and J-M Froidefond
1) Spectroradiometric measurements
2) Examples of SPMC quantification in the Bay of Biscay,the French Guiana and the Congo coastal waters
3) Inversion of spectra from the WASI code (P. Gege)
Spectroradiometric measurements
Radiance measurements with Trios sensors located
above + 2cm and below -2cm (Lu). ± 1cm
Irradiance measurement with a Triossensor (Ed). 350nm – 950nm
Calibrations in air before or after thesurvey at “Trios”
Froidefond and Ouillon, 2005
),0(),0(*98.0)( durs ELR
Remote sensing reflectance
Example of reflectance spectra (Rrs (l)
Water radiance (Lu)
Irradiance (Ed)
Remote sensing reflectance Rrs(l)
Rrs(sr-1) = Lu/Ed
Shadow effects relatively low
Water radiance just below the sea surface
Turbid waters (> 30mg/L)
Very high shaddow effects
Radiance measured above the sea surface
Backscattered light attenuated by theshadow of the sensor
Clear waters
Water radiance just above the sea surface
Identification and quantification of suspended particles
Gironde area
Arcachon areaGironde area : quantification ofmineral particles (PNEC)
Adour areaArcachon area(CNES, Kalideos-Littoral)Intertidal and subtidal mapping
French Guiana (IRD, PNEC
Optic-Congo (SHOM)
Bay of Biscay (SHOM, INSU, Region)Optic-Med (SHOM)
Bissecotte (IRD)
About 400 spectra recorded during differentoceanographic surveys in case 2 waters. At eachstation, hydrologic data (SPM, CDOM, Chlorophyll-aor fluorescence, CDOM
SPM concentrations in the Bay of Arcachon from SPOT data
Arcachon
Gabon and Congo coastal waters (Optic-Congo survey, SHOM, Schmeltz et al., 2009)
SPMC = 1260.7*Rrs(B1)
No relationship
(Bru, 2010)
Summary of the measurements
SPMC between 1 and 30 mg/L
B1 (Modis Band 1. 620nm – 670nm)
Gironde (turbid plume): SPMC(mg/L) = 1142.4*Rrs(B1)Adour R. (Petus et al. 2010): SPMC(mg/L) = 1007.3*Rrs(B1)French Guiana (turbid waters): SPMC(mg/L) = 1377.6*Rrs(B1)Arcachon bay (Bru, 2010): SPMC(mg/L) = 1260.7*Rrs(B1)Congo coast : No relationshipIrish Sea (Binding et al., 2005): SPMC(mg/L) = 516.3*Rrs(665nm) + 1.13Mississipi plume (Miller et al): SPMC(mg/L) = 1140.3*Rrs(B1) – 1.9
Different empirical relationships, explained by the optical properties of thewater components:Various clay minerals (illite, kaolinite, chlorite, smectite…), quartz, micas…Various granulometric size and flocsConcentration and composition of organic particles and CDOM.
Comparison with a spectra simulation code (WASI)
P. Gege, 2004
Initial values
Fit parameters(output data)
WASI, Water color simulator (P. Gege, 2004)
Chlorophyllconcentration
SPM concentration
Exponent of yellowsubst. absorption
Yellow subst. (CDOM)concentration
IOP (a, bb, Kd)
Original spectrum
Fitted spectrum
Model and options:Rrs-(l) = frs*[bb(l) / (a(l) + bb(l))] and Rrs+(l) = xi*Rrs-(l)/(1-sigma-*R)+Rsurf