Phytoplankton-Absorption aus SCIAMACHY und MERIS-Satellitendaten zur Verbesserung globaler Abschätzungen der marinen Primärproduktion (PASAT)
Final Report Abstract
Information on phytoplankton light absorption is necessary to derive accurate estimates of marine chl a concentration and primary production. Global satellite data on photosynthetically active radiation and chl a concentration are available from a suite of satellite imagers like CZCS, SeaWiFS, MODIS, MERIS and others, but spectral information of absorption and composition by phytoplankton and other water constituents is still lacking. Within this project we used Differential Optical Absorption Spectroscopy (DOAS) to study the retrieval of phytoplankton distribution and absorption with the satellite sensor Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY). In particular, we used in-situ measured phytoplankton absorption spectra from different Atlantic Ocean expeditions with RV Polarstem in the retrieval of phytoplankton absorption from SCIAMACHY data. These in-situ spectra were from sites with different phytoplankton composition: one from a well-mixed phytoplankton community, one from a site where only cyanobacteria were present and one from a site where diatoms dominated the community by nearly 80%. By using the different in-situ phytoplankton absorption data in the satellite retrieval, the characteristic absorption spectra for these phytoplankton communities were clearly identified in the SCIAMACHY data in the range of 430 to 500 nm (Vountas et al. 2007, Bracher et al. in prep.). The overall phytoplankton biomass estimates retrieved from SCIAMACHY data agreed well with collocated MODIS and MERIS data (Vountas et al. 2007). Globally distributed pigment concentrations for these characteristic phytoplankton groups for two monthly periods (FebMarch 2004 and Oct-Nov 2005) were derived from these differential absorptions by including the information of the sensor's optical paths within the water column (i.e. light penetration depth) according to Vountas et al. 2007. The satellite retrieved information on cyanobacteria and diatoms distribution matched well with the concentrations measured at collocated water samples with HPLC technique and concentrations derived from the global model analysis with the NASA Ocean Biogeochemical Model (NOBM) and in-situ measurements (Bracher et al. in prep). Results are of great importance for global modelling of marine ecosystem and climate change studies regarding changes in the ocean. Through a better knowledge of the major player within the biological pump and by that of the sinks and sources of CO2 in the ocean, a contribution will be made to a better understanding of changes in the world's climate as well as to the understanding of the marine food web. The results of the project are the basis of future studies performed within the funding frame of the Helmholtz University Young Investigator Group PHYTOOPTICS and an EU project SHIVA. The objectives of future studies are concentrating on the use of biooptical information obtained from several different satellite sensors, such as SCIAMACHY, GOME-2, OMI, MODIS and MERIS. This additional biooptical satellite information shall be used for developing an improved MERIS phytoplankton biomass retrieval, as an input basis for primary production modelling and for developing improved atmospheric trace gas retrievals by accounting for the oceanic optical signal. The maps on the distribution of major phytoplankton groups and marine primary production are planned to be used within several climate change studies (e.g. for identifying biogenic sources of greenhouse gas and short lived halogenated species, carbon cycle estimations).
Publications
- Bracher A., Dinter T., Sierk B., Vountas M., Hoyningen-Huene W., Richter A., Burrows J.P. (2005) Comparisons of phytoplankton concentrations from MERIS and SCIAMACHY measurements. Proceedings of the MERIS (A)ATSR Workshop 2005, ESRIN/ESA, Frascati, Italy, ESA Publications Division, ESTEC, Nordwijk, The Netherlands, SP-597. (Siehe online unter: http://envisat.esa.int/workshops/meris_aatsr2005//participants/522/paper_Bracher_MERISWS2005.pdf)
- Bracher A., Vountas M., Dinter T., Röttgers R., Doerffer R., Bun-ows J.P. (2006) "Retrieval of phytoplankton distribution and light disorption from space borne SCIAMACHY data using Differential Optical Absorption Specfroscopy'. Poster: Ocean Optics XVIII, 9-13 Oct 2006, Delta CenfreVille, Montreal, Canada
- Bracher A., Vountas M., Dinter T., Röttgers R., Doerffer R., Burrows J.P. (2006) Retrieval of phytoplankton distribution and light absorption from space borne SCIAMACHY data using Differential Optical Absorption Spectroscopy. Proceedings of the Ocean Optics XVIII, 9-13 Oct 2006, Delta CenfreVille, Montreal, Canada
- Bracher A., Vountas M., Dinter T., Röttgers R., Peeken I., Bemitt E., Burrows J.P. (2007) "Phytoplankton distribution and light absorption from space using Differential Optical Absorption Spectroscopy", Talk: ENVISAT Symposium 2007, 26 Apr 2007, Montreux, Switzerland
- Bracher A., Vountas M., Dinter T., Röttgers R., Peeken I., Bemitt E., Burrows J.P. (2007) Phytoplankton distribution and light absorption from space using Differential Optical Absorption Spectroscopy. In: Proceedings of the ENVISAT Symposium 2007, 23-27 Apr 2007, Montreux, Switzerland, ESA Publications Division, Nordwijk, The Netherlands.
- Vountas M., Dinter T., Bracher A., Burrows J.P., Sierk B. (2007) Spectral Studies of Ocean Water with Space-borne Sensor SCIAMACHY using Differential Optical Absorption Spectroscopy (DOAS). Ocean Science 3: 429-440 and corrigendum: Vountas, M., Dinter, T., Bracher, A., Burrows, J. P., and Sierk, B.: Corrigendum to "Spectral studies of ocean water wath space-borne sensor SCIAMACHY using Differential Optical Absorption Spectroscopy (DOAS)" published in Ocean Sci., 3, 429-440, 2007, Ocean Sci., 3, 483-483,2007
- Bracher A. (2008) "Global observation of marine phytoplankton with satellite and in situ measurements". Meteorological Colloquium, IFM-Geomar, 13 Mar 2008, Kiel, Germany, Germany
- Bracher A. (2008) "Globale Beobachtung von marinem Phytplankton mit spectral hochaufgelösten Satellitendaten", Physikalisches Kolloquium des Fachbereichs Physik/Elektrotechnik, University Bremen, 24 Jan 2008, Bremen, Germany
- Bracher A. (2008) Detallierter Blick aus dem All - Meeresalgen global beobachtet, Fachbeitrag in zvf-Zeitschrift für Geodäsie, Geoinformation und Landmanagement. Wißner-Verlag GmbH & Co. KG, Augsburg. Band 133/4: 254-261
- Bracher A., Vountas M., Dinter T., Burrows J.P., Röttgers R., Peeken I. (2008) Observation of cynaobacteria and diatoms from space using Differential Optical Absorption Spectroscopy on SCIAMACHY data". Talk: 5th EGU General Assembly 2008, 16 April 2008, Vienna, Ausdia
- Bracher A., Vountas M., Dinter T., Burrows J.P., Röttgers R., Peeken I. (2008) Observation of phycoerythrine containing phytoplankton and other phytoplankton groups from space using Differential Optical Absorption Spectroscopy on SCIAMACHY data". Talk: 37th COSPAR, 17 July 2008, Montreal, Canada
