In order to assess the ocean optics especially in the open waters and identify directly the distribution of phytoplankton groups and other water constituents in these waters, we take in-situ water samples and direct optical measurements during various cruises since 2007 with German research vessels (RV) RV Polarstern, RV Maria S. Merian, RV Heincke, RV Poseidon, RV Meteor and RV Sonne. Ground-truth data is essential for the development of oceanic radiative transfer, retrieval of remote sensing data and the use of various methods to analyse composition of particles, especially phytoplankton, and coloured dissolved organic matter from optical measurements. The derived inherent optical properties (IOPs) and apparent optical properties (AOPs) from the in situ measurement (see details on instrumentation) can not only be used for satellite retrieval development and data validation but can be processed as well by ocean color algorithms to derive geophysical quantities such as phytoplankton, colored dissolved organic matter, particle abundance and composition.
The in-situ biooptical and biogeochemical data sampled at more than 20 cruises and three campaigns of the PHYTOOPTICS group have been used to study regional coupling of benthos and pelagial (Brandt et al. 2014, Cedhagen et al. 2014), to identify biogeochemical provinces (Taylor et al. 2011, Goncalves-Araujo et al. 2015, Goncalves-Araujo et al. 2018) and water masses (Goncalves-Araujo et al. 2016), to assess phytoplankton growth (Cheah et al. 2013, Trimborn et al. 2015) and to find the linkage to oceanic emissions (Zindler et al. 2013, Hepach et al. 2015, Hepach et al. 2016, Booge et al. 2016, Lennartz et al. 2017, Schlundt et al. 2017, Booge et al. in press), but also to construct and evaluate ocean color retrievals (Bracher et al. 2009, Sadeghi et al. 2012, Taylor et al. 2013a, Cherkasheva et al. 2013, Cherkasheva et al. 2014, Cherkasheva 2014, Soppa et al. 2014, Bracher et al. 2015, Losa et al. 2017, Liu et al. 2018, Liu et al. 2019, Bracher et al. 2020).
Past cruises
References: see group's peer-reviewed publications and
Cheah, W., Taylor, B. B., Wiegmann, S., Raimund, S., Krahmann, G., Quack, B., Bracher A. (2013) Photophysiological state of natural phytoplankton communities in the South China Sea and Sulu Sea. Biogeosciences Discuss., 10, 12115-12153, doi:10.5194/bgd-9-4727-2012.
Cherkasheva, A. (2014) Greenland Sea primary production with respect to changes in sea ice cover. PhD thesis, Department of Physics and Electrical Engeneering, University Bremen, 168 p., http://elib.suub.uni-bremen.de/edocs/00103817-1.pdf
Mariana Soppa Prof. Dr. Astrid Bracher
AC-s (WetLABS) Spectrometer used for continuous sampling of hyperspectral IOPs (attenuation, absorption) of total and coloured dissolved organic matter (CDOM). Set-up of continuous surface water optical measurements with AC-s and debubbler system, flow-control and automatic switch system to filter in order to have regular alternation between measurements of total IOPs and CDOM IOPs.