Phytoplankton Functional Types

Synergistic Exploitation of Hyper-and Multispectral Sentinel-Measurements to Determine Phytoplankton Functional Types at Best Spatial and Temporal Resolution.

To overcome the short-comings of current multi-spectral PFT products (supplying either knowledge on dominant groups or size fractions only, data products with strong linkage to a-priori-information) and PhytoDOAS data products (with only low temporal and spatial coverage), the project's objective is a substantial improvement of retrieving phytoplankton groups with defined accuracy and good spatial and temporal coverage. This shall be done by developing a synergistic product which contains the Chl-a (biomass) of several PFT by using complementary information from multi- and hyper-spectral satellite ocean colour data. This algorithm can be later applied to produce a synergistic PFT product from TROPOMI (on Sentinel-5-Precursor, Sentinel-4, Sentinel-5) and OLCI (on Sentinel-3).

The study involved improving existing PFT algorithms that can obtain chlorophyll concentrations (Chla, mg/m3) of multiple phytoplankton types from space. This included: (i) hyperspectral data sets from SCIAMACHY (with 60 km by 30km spatial resolution and global coverage within 6 days) processed with the PhytoDOAS method (Bracher et al. 2009; Sadeghi et al. 2012); and (ii) the chlorophyll product (OC-CCI) from multi-spectral data sets (SeaWiFS, MERIS, MODIS) processed with the OC-PFT method by Hirata et al. (2011), as modified by Soppa et al. (2014) and further adjusted for optimal settings to retrieve best results. New adaptations were verified for PhytoDOAS via sensitivity studies with the coupled ocean-atmosphere radiative transfer model SCIATRAN and for OC-PFT via validation with a large global in-situ PFT data set based on High Performance Liquid Chromatography (HPLC) pigments (Losa et al. in prep.).

The synergistic PFT algorithm was conceived to generate global PFT Chla products of diatoms, coccolithophores and cyanobacteria (Losa et al. in prep) from 2002 to 2012 at daily 4 km resolution. The algorithm is based on an optimal interpolation technique (Gandin and Hardin 1965) and applied for combining improved products of OC-PFT and PhytoDOAS, with PhytoDOAS giving the physical value within the large pixel and OC-PFT giving the sub- pixel variation by given a certain weight to each of these inputs. The weights are defined in terms of Kalman filtering, reflecting the error statistics in both products. The algorithm can be run on open source software and the product outputs are provided as NetCDF. The algorithm inputs are available in ASCII or NetCDF.

SynSenPFT output was successfully validated with in-situ PFT data sets and intercompared to the same outputs from the NASA ocean biogeochemical model (NOBM, Gregg and Casey 2007) and two similar satellite data sets (Ciotti et al 2006, Brewin et al. 2010, respectively) describing the composition of phytoplankton in terms of size. Validation against in-situ data showed globally robust results for all three SynSenPFT products (Losa et al. 2012): SynSenPFT Chla show good comparison (among all statistical parameters) to in-situ PFT for coccolithophores and diatoms. For cyanobacteria RMSD and MAE are still acceptable, however no correlation was found. Inter-comparison of other global satellite products and to NOBM products at monthly resolution shows reasonable similar spatial and temporal distribution and magnitudes for all three SynSenPFT products (Losa et al. in prep.). Additional the inter-comparison analyses, including calculations of correlations, trends and bloom phenology, was carried out through time series analyses for specific Longhurst provinces encompassing polar, oligotrophic, tropical and upwelling regions, (Soppa et al. in prep.). Generally, SynSenPFT products are similar to the corresponding c-PSC and, for some provinces, to NOBM Chla (especially for diatoms). Differences in the magnitude depend on the PFT and region. Only a few significant trends were detected and these were consistent for c-PSC and SynSenPFT for Canarian Coastal and the Southwest Atlantic Shelf provinces. The phenological indices of c-PSC and NOBM Chla were consistent within two to three months, respectively to SynSenPFT products. PSC products indicated longer bloom duration, which may be explained by these products covering more algal groups than the ones detected by SynSenPFT. In summary, the first version of SynSenPFT shows robust results based on its uncertainty determined via validation and intercomparison to other products.

All the data sets compiled and used in the frame of this project are available on request and all the project documents (deliverables, technical notes), the SynSenPFT presentations and publications, are accessible via the project website.

Bracher A., Bouman H., Bricaud A., Brewin R., Brotas V., Ciotti A. M., Clementson L., Devred E., Di Cicco A., Dutkiewicz S., Hardman-Mountford N., Hickman A., Hieronymi M., Hirata T., Losa S., Organelli E., Raitsos D., Uitz J., Vogt M., Wolanin A. (2017) Obtaining Phytoplankton Diversity from Ocean Color: A Scientific Roadmap for Future Development. Frontiers in Marine Science 4: 55.
http://journal.frontiersin.org/article/10.3389/fmars.2017.00055/full

Mouw, C. B., Hardman-Montford, N., Alvain, S., Bracher A.,Brewin R., Bricaud A., Ciotti A., Devred E., Fujiwara A., Hirata T., Hirawake T., Kostadinov T., Roy S., Uitz J. (2017) A Consumer’s Guide to Satellite Remote Sensing of Multiple Phytoplankton Groups in the Global Ocean. Front. Mar. Sci. 4: 00041, Specialty Section Ocean Observation, Research Topic “Colour and Light from Earth Observation”.
http://journal.frontiersin.org/article/10.3389/fmars.2017.00041/full

Kostadinov T., Cabré A., Vedantham H., Marinov I., Bracher A., Brewin R., Bricaud A., Hirata T., Hirawake T., Hardman-Mountford N., Mouw C., Roy S., Uitz J. (2017) Inter-Comparison of Phytoplankton Functional Types Derived from Ocean Color Algorithms and Earth System Models: Phenology. Remote Sensing of Environment
http://www.sciencedirect.com/science/article/pii/S003442571630459X

Soppa M. A., Völker C., Bracher A. (2016) Diatom Phenology in the Southern Ocean: Mean Patterns, Trends and the Role of Climate Oscillations. Remote Sensing 8: 420, doi:10.3390/rs8050420
http://www.mdpi.com/2072-4292/8/5/420

Booge D., Marandino C. A., Schlundt C., Palmer P. I., Schlundt M., Atlas E. L., Bracher A., Saltzman E. S., Wallace D. W. R. (2016) Can simple models predict large scale surface ocean isoprene concentrations? Atmospheric Chemistry and Physics 16: 11807-11821, doi:10.5194/acp-16-11807-2016
http://www.atmos-chem-phys.net/16/11807/2016/acp-16-11807-2016.pdf

Wolanin A., Soppa M. A., Bracher A., (2016) Investigation of spectral band requirements for improving retrievals of phytoplankton functional types. Remote Sensing 8: 871; doi:10.3390/rs8100871
http://www.mdpi.com/2072-4292/8/10/871

Dinter T., Rozanov V., Burrows, J. P., Bracher A. (2015) Retrieval of light availability in ocean waters utilizing signatures of vibrational Raman scattering in hyper-spectral satellite measurements. Ocean Science 11: 373-389.
http://www.ocean-sci.net/11/373/2015/

Rozanov V.V., Dinter T., Rozanov A. V., Wolanin A., Bracher A., Burrows J.P. (submitted 18 Nov 2016) Radiative transfer modeling through terrestrial atmosphere and ocean accounting for inelastic scattering processes: Software package SCIATRAN. J. Quant. Spectrosc. Rad. Transfer

Muller-Karger F.E., Hestir E., Ade C., Turpie K., Roberts D., Siegel D., Miller R., Humm D, Izenberg N., Keller M., Morgan F., Frouin R., Dekker A., Gardner R., Goodman J., Schaeffer B., Franz B., Pahlevan N., Mannino A. G., Concha J. A., Ackleson S.G., Najjar R., Cavanaugh K., Romanou A., Tzortziou M., Boss E., Pavlick R., Schimel D., Freeman A., Rousseaux C. S., Dunne J., Long M., Klein E., McKinley G., Letelier R., Roffer M., Goes J., Bracher A., Arrigo K. R., Dierssen H., Zhang X., Davis F., Best B., Guralnick R., Moisan J., Sosik H. M., Kavanaugh M., Kudela R., Mouw C. B., Barnard A., Palacios S., Roessler C., Drakou E., Appeltans W. (submitted) Monitoring biodiversity in the coastal ecotone from space. Submitted to Nature 28 Nov 2016 ̧ reference number: 2016-11-16309

Muller-Karger F.E., Hestir E., Ade C., Turpie K., Roberts D., Siegel D., Miller R., Humm D, Izenberg N., Keller M., Morgan F., Frouin R., Dekker A., Gardner R., Goodman J., Schaeffer B., Franz B., Pahlevan N., Mannino A. G., Concha J. A., Ackleson S.G., Najjar R., Cavanaugh K., Romanou A., Tzortziou M., Boss E., Pavlick R., Schimel D., Freeman A., Rousseaux C. S., Dunne J., Long M., Klein E., McKinley G., Letelier R., Roffer M., Goes J., Bracher A., Arrigo K. R., Dierssen H., Zhang X., Davis F., Best B., Guralnick R., Moisan J., Sosik H. M., Kavanaugh M., Kudela R., Mouw C. B., Barnard A., Palacios S., Roessler C., Drakou E., Appeltans W. (submitted) Monitoring biodiversity in the coastal ecotone from space. Submitted to Nature 28 Nov 2016 ̧ reference number: 2016-11-16309

Losa S., Soppa M. A., Dinter T., Wolanin A., Rozanov R., Brewin R., Bricaud A., Bracher A. (to be submitted by 15 Jan 2016) Synergistic exploitation of hyper- and multispectral Sentinel-measurements to determine Phytoplankton Functional Types at best spatial and temporal resolution (SynSenPFT). Submitted to Frontiers in Marine Science, Research Topic

Muller-Karger F.E., Hestir E., Ade C., Turpie K., Roberts D., Siegel D., Miller R., Humm D, Izenberg N., Keller M., Morgan F., Frouin R., Dekker A., Gardner R., Goodman J., Schaeffer B., Franz B., Pahlevan N., Mannino A. G., Concha J. A., Ackleson S.G., Najjar R., Romanou A., Tzortziou M., Boss E., Pavlick R., Schimel D., Freeman A., Rousseaux C. S., Dunne J., Long M., Letelier R., Behrenfeld M., McKinley G., Roffer M., Goes J., Bracher A., Arrigo K. R., Dierssen H., Zhang X., Davis F., Best B., Guralnick R., Moisan J., Sosik H., Kavanaugh M., Kudela R., Mouw C. B., Barnard A., Palacios S., Roessler C., Cavanaugh K., Appeltans W. (to be submitted) Monitoring coastal marine and wetland biodiversity First: Nature Geosciences

Schlundt C., Marandino C. A., Tegtmeier S., Lennartz S., Bracher A., Cheah W., Krüger K., Quack B. (to be submitted) Ocean cycling, air-sea gas exchange and atmospheric transport of oxygenated volatile organic carbons in the western Pacific convective center. To be submitted to Biogeosciences

Soppa M., Losa S., Bricaud A., Brewin R. J., Bracher A. (to be prepared) Synergistic product intercomparison to other satellite and model products analysing time series data in different biogeochemical provinces