DEVELOPMENT OF MERIS LAKE WATER ALGORITHMS: VALIDATION RESULTS FROM EUROPE

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1 DEVELOPMENT OF MERIS LAKE WATER ALGORITHMS: VALIDATION RESULTS FROM EUROPE Antonio Ruiz-Verdú (1) *, Sampsa Koponen (2), Thomas Heege (3), Roland Doerffer (4), Carsten Brockmann (5), Kari Kallio (6), Timo Pyhälahti (6), Ramón Peña (1), Ángel Polvorinos (7), Jörg Heblinski (3), Pasi Ylöstalo (6), Laura Conde (1), Daniel Odermatt (8), Victor Estellés (9) and Jouni Pulliainen (10) (1) Centre for Hydrographic Studies - CEDEX (2) Helsinki University of Technology (TKK) (3) EOMAP GmbH & Co.KG (4) GKSS Forschungszentrum Geesthacht (5) Brockmann Consult (6) Finnish Environment Institute (SYKE), (7) University of Sevilla, (8) University of Zurich - Irchel, (9) University of Valencia, (10) Finnish Meteorological Institute (FMI), * Currently at: INTA (Spain) ruizva@inta.es

2 OUTLINE 1. Introduction 2. Algorithm overview 3. Validation campaigns 4. Validation results 5. Conclusions

3 1. Introduction ESA ITT: Development of MERIS Lake Water Algorithms ( MERIS LAKES ). January 2007 June monitoring/meris_lakes.html MAIN TASKS: Algorithm development (Lake water processors) Implementation as a BEAM plug-in module Validation of the processors Results at:

4 2. Algorithm overview 2nd MERIS/(A)ATSR User Workshop September 2008 ESA/ESRIN L1 TOA Radiances, O 3, Surface Pressure, Solar Irradiance (TOA) Atmospheric correction (AC) neural network (NN) L_path Transmittance AOT Å coeff. Solar and observation angles R_Lw (water leaving reflectance) VAL NN Case 2 Regional (C2R) NN Boreal Lakes (BL) NN Eutrophic Lakes (EUL) BIO-OPTICAL MODELS VAL Concentrations of Water quality variables, IOPs, quality indicator

5 2. Algorithm overview Summary of Processor s products 2nd MERIS/(A)ATSR User Workshop September 2008 ESA/ESRIN Water leaving radiance reflectance, R_Lw (9 bands) Chlorophyll concentration (Chl-a) Total Suspended Matter concentration (TSM) CDOM (gelbstoff) absorption coeff (a_gelb)* Path radiance reflectance, R_Lpath (9 bands) Transmittance (9 bands) Aerosol optical thickness (AOT) Angstrom coefficient Scattering coefficient of TSM at 443 nm (b_tsm) Phytoplankton absorption coeff. at 443 nm (a_pig) Total absorption coeff. at 443 nm (a_total) Min. Irrad. atenuattion coeff. (K_min) Signal depth (Z_90_max) Chi_square

6 3. Validation campaigns Validation sites Gradient of water types and SIOPs Finland, 4 lakes Lake Constance Low to moderate Chl-a Moderate to high CDOM Spain, 5 lakes Low Chl-a Areas of moderate TSM Moderate to very high Chl-a Cyanobacteria frequent

7 3. Validation campaigns MAIN MEASUREMENTS AOPs: Above and in water radiometry (ASD, Ramses) IOPs in situ: absorption and scattering (Wetlabs ac-s, ac-9); backscattering (ECO bb9) IOPs lab: Filter pad method WQ constituents: Chl-a (HPLC or spectrophotometric), TSM (gravimetric), CDOM (spectrophotometric) Atmosphere: Cimel 318NE in situ; Aeronet

8 3. Validation results ATMOSPHERIC CORRECTION Two products were validated with in situ data: L1 L_TOA NN AC R_Lw L1 L_TOA ICOL NN AC R_Lw (Preprocessed with ICOL) ICOL (Improved Contrast between Ocean and Land) Correction method for the Adjacency Effect Not yet released as a Beam plug-in Santer R., Zagolski F., and Gilson M. (2007). Université du Littoral, France, ICOL ATBD, Version 0.1, Feb. 28, 2007.

9 4. Validation results ATMOSPHERIC CORRECTION RS Reflectance (+0) Station LA April , Lake Constance C2R v125, 9 pixels ICOL C2R, 9 pixels RAMSES radiometer RLw (sr-1) IZNÁJAR, STATION A, IN SITU EUL ICOL+EUL wavelength [nm] Wavelength (nm) LAKE CONSTANCE (Germany) IZNÁJAR RESERVOIR (Spain)

10 4. Validation results ATMOSPHERIC CORRECTION R water leaving 7 x S1 BOR S2 BOR S3 BOR S1 ICOL BOR S2 ICOL BOR S3 ICOL BOR S1 insitu S2 insitu S3 insitu RLw (sr-1) ALMENDRA, STATION A, FIELD EUL ICOL+EUL Wavelength (nm) Wavelength (nm) LAKES VESIJÄRVI and PÄIJP IJÄNNE (Finland) ALMENDRA RESERVOIR (Spain)

11 4. Validation results WATER QUALITY PRODUCTS TSM (mg/l) TSM (mg/l) y = 2.33x R 2 = y = 1.28x R 2 = 0.64 MERIS C2R MERIS BL 4.0 GER 2.0 FIN SPA IN SITU 2.0 GER FIN SPA IN SITU C2R PROCESSOR BOREAL PROCESSOR

12 4. Validation results WATER QUALITY PRODUCTS MERIS C2R Chl-a (mg/m 3 ) 18.0 y = 2.21x R 2 = GER FIN SPA IN SITU MERIS EUL Chl-a (mg/m 3 ) y = 1.26x R 2 = GER FIN SPA IN SITU C2R PROCESSOR EUTROPHIC PROCESSOR

13 4. Validation results WATER QUALITY PRODUCTS 2nd MERIS/(A)ATSR User Workshop September 2008 ESA/ESRIN 13 April April April 2008 C2R processor, version AOD 550nm [1/m] TSM [g/m 3 ] Chl a [mg/m 3 ] acdom a_gelb [1/m] Water Quality maps. Lake Constance

14 4. Validation results WATER QUALITY PRODUCTS 2nd MERIS/(A)ATSR User Workshop September 2008 ESA/ESRIN June 4, 2007 S1 S2 S3 Paa In situ MERIS TSM map. Finland

15 5. Conclusions (1) 1. Atmospheric correction Good agreement in green-red bands General improvement with ICOL Deviations in very humic or high chl-a lakes 2. Water constituents Linear response, some over- and underestimations Acceptable errors at low concentration ranges Larger errors in turbid lakes

16 5. Conclusions (2) First Lake Water Processor for MERIS Available at Beam Visat processors for different water types (user decides) Flexible: Easy tuning for other water types possible

17 Thank you for your attention!

18 DEVELOPMENT OF MERIS LAKE WATER ALGORITHMS: VALIDATION RESULTS FROM EUROPE Antonio Ruiz-Verdú (1) *, Sampsa Koponen (2), Thomas Heege (3), Roland Doerffer (4), Carsten Brockmann (5), Kari Kallio (6), Timo Pyhälahti (6), Ramón Peña (1), Ángel Polvorinos (7), Jörg Heblinski (3), Pasi Ylöstalo (6), Laura Conde (1), Daniel Odermatt (8), Victor Estellés (9) and Jouni Pulliainen (10) (1) Centre for Hydrographic Studies - CEDEX (2) Helsinki University of Technology (TKK) (3) EOMAP GmbH & Co.KG (4) GKSS Forschungszentrum Geesthacht (5) Brockmann Consult (6) Finnish Environment Institute (SYKE), (7) University of Sevilla, (8) University of Zurich - Irchel, (9) University of Valencia, (10) Finnish Meteorological Institute (FMI), * Currently at: INTA (Spain) ruizva@inta.es