1. The colour of the Mediterranean Sea: global versus regional bio-optical algorithm evaluation and development of regional chlorophyll dataset in the framework of MERSEA Gianluca Volpe 1, Rosalia Santoleri 1, Salvatore Marullo 2, Simone Colella 1 1 Istituto di Scienze dell’Atmosfera e del Clima – sezione di Roma 2 Ente per le Nuove tecnologie l’Energia e l’Ambiente – Centro Ricerche Frascati r.santoleri@isac.cnr.it; http://gos.ifa.rm.cnr.it;

2. The aims are: 1.to identify and develop of an optimal algorithm for the Mediterranean sea to produce high quality ocean colour datasets for the region. 2.to provide an accurate and consistent stream of ocean colour data at a resolution and format compatible with operational forecasting of the Mediterranean Marine Environment. 3.To setup the Mediterranean Forecasting System (MFS) core products: satellite and model structure NRT MODIS and the SeaWiFS reanalysis from 1997 to 2005 A new regional algorithm for Chlorophyll retrieval Impact of OC regional product in models

3. In situ chlorophyll-a data: 1144 chlorophyll profiles for satellite data validation Mediterranean Ocean Color CAL/VAL DATA SETS 28 Mediterranean cruises: from 1997 up to now were organized by ISAC in the framework of Italian National Projects + 2 permanent stations Bio-optical measurements: 155 chl/opt measurements to define the Mediterranean regional algorithm (red points) Optical measurements: 938 SIMBADA for Rrs validation (blue points)

4. CAL/VAL cruise in the Eastern Mediterranean CNR-JRC joint cruise in Sep 2006

5. MEDOC4 : R is log 10 of either the 443/560 or the 490/555 or the 510/555 band reflectance ratios. The switch from one band ratio to another one is based on the chlorophyll concentration itself (the Maximum is Chosen) THE NEW MEDITERRANEAN ALGORITHM (Volpe et al. RSE, 2006 in press) Algorithms ALL N = 155OWP < 0.4 N = 105OWP > 0.4 N= 50 r2r2 RPDAPDr2r2 RPDAPDr2r2 RPDAPD OC40.886.71000.77127,1290,62-10,331.5 MedOC40.910.029.20.887.825.90.83-12.334.5

6. In situ Satellite MED_OC4

7. Validation of MBR A SIMBADA- SeaWiFS RRS matchup dataset was build to test the accuracy of the satellite band ratios over the Mediterranean Sea.

8. SeaBAM N=1174 Mediterranean N=156 Optical characteristics: Mediterranean vs Global 1.Low Chlorophyll: Med Band Ration < Global Band Ratio 2.Max Ratio choice similar for Med and Global 3.Is the Med Sea Greener or less Blue then the Global Ocean?

9. Is the Med Sea Greener or less Blue then the Global Ocean? -blue (30%); +Green (15%) -blue (35%); +Green (18%) -blue (32%); Green similar Med and Global tend to converge + blue (23%); - Green (35%)

10. MODIS & MERIS Algorithm Validation MODISMERIS chl whole range N=156r²RPDAPDr²RPDAPD Standard Algorithm0,7889,3104,60,76108,1118 Regional Algorithm0,787,830,80,728,133,5 0.01<chl<0,4 N=110 Standard Algorithm0,78133,7134,80,79153,3154 Regional Algorithm0,7211,628,90,7713,531

11. MODIS vs SeaWiFS regionalregional globalglobal

12. MERIS vs SeaWiFS regionalregional globalglobal

13. N°RMSBIASR2R2 RPDAPD SeaWiFS920.47-0.030.82-0.948.4 MODIS780.54-0.20.75-4.39.9 MERIS810.65-0.420.83-8.511.3 MBR validation against in situ measurements: Examined period: 2003-2004

14. The SeaWiFS reanalysis from 1997 to 2005: reprocessing of the entire Mediterranean Sea L1A archive using MedOC4 Algorithm Available at the MERSEA web site

15. SeaWiFS Re-PROCESSING ON ESA-CNR GRID infrastructure UICE SE WN:Node01.. ….Node16 Gridtest03.esrin.esa.intGrid0007.esrin.esa.int Se0.artov.rm.cnr.it 1) Globus-job-submit 2) Globus-job-status 3) Globus-job-get-output Globus-url-copy UI=User Interface SE=Storage element CE=Computer Element WN=Worker node N° SeaWiFS pass= 6127 Total processing time ~ 4 days

16. Previous algorithm NEW algorithm Difference OLD-NEW OC4.V4 Med OC4(OC4.V4) – (Med OC4) 0 -0.1 0.2 0.01 5 5 2 July 2004 The GRID products output

17. OC4.V4 Med OC4 (OC4.V4) – (Med OC4) 1999 yearly average

18. Impact on Primary Productivity The use of MedOC4 chlorophyll in PP Models reduces the annual PP estimate by about 40% and 10% respect to corresponding estimate made using OC4 and BRIC02 Global Model + Chl(OC4) Global Model + Chl(BRIC02) Global Model + Chl(MedOC4)

19. Other MED Optical characteristic C tot C sat Z e C tot Antoine and Morel, 1996 (yellow) Morel and Berthon, 1989 (red) Uitz et al., 2006 (green) Colella 2006 (blue) Morel and Berthon, 1989 (red) Morel and Maritorena, 2001 (green) Colella 2006 (blue)

20. Impact on Primary Productivity: global vs regional PP model (a) Global Model + Chl(OC4) (b) Global Model + Chl(BRIC02) (c) Global Model + Chl(MedOC4) (d) Regional Model + Chl(BRIC02) (e) Regional Model + Chl(MedOC4) MAX PP in SPRING

21. Monthly chlorophyll climatology maps derived from SeaWiFS data, processed by GOS-ISAC-CNR, for the year 1997-2004. Monthly chlorophyll concentration maps obtained from OGS/OPA transport model after 10y spin-up. Mediterranean biogeochemical coupled model for future Short term Forecasting: Model sensitivity to a longitudinal variable extinction coefficient Crise et al, 2006

22. Overall overestimation of surface Chlorophyll underestimates spring bloom in NW Relative error is below 0.8 relative error lower in late-Autumn Winter error bias constant throughout the basin (positive anomaly in the W.Med in Spring) Chl Anomaly Map [Chl(data)-Chl(model)]/Chl(data)) Basin averaged relative anomaly

23. Concluding remarks The analysis demonstrate that OC overestimation chlorophyll in the Med is due to its peculiar optical characteristics. the use of regional algorithm is mandatory to produce high quality OC products for ecosystem model assessment and assimilation The MFS requirement for the GlobColour Project is to give access to the L2/L3 products (single sensors collocated Rrs data) from which we can produced specific regional L4 products taking into account the model community needs. Regional OC products should be produced in the TAC

24. The Mediterranean L4 products using L2P Medspiration data Data mergingISAC Optimal Interpolation Data delivery on the GOS-ISAC web-site Data quality controll Night-time SST using MF algorithm Cloud detection SST daily composite binning on model grid (1/16x1/16) MF AVHRR acquisition Atlantic buffer zone + west Med Night-time SST using Pathfinder algorithm Cloud detection SST daily composite binning on model grid (1/16x1/16) ISAC AVHRR acquisition Entire Mediterranean L2P Medspiration Products

29. To save the Mediterranean Sea from environmental problem look at the combination of satellites and ocean forecast!! Conclusions