In-situ optical measurements

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

  • RV Polarstern, ANT XXIV-1, Bremerhaven (Germany) to Cape Town (South Africa) in Oct/Nov 2007
  • RV Polarstern, ANT XXIV-4, Punta Arenas (Chile) to Bremerhaven, Apr/May 2008
  • RV Maria S. Merian, MSM09-1, Bremen (Germany) to St. John’s (Canada) in Jul/Aug 2008
  • RV Polarstern, ANT XXV-1, Bremerhaven to Cape Town, Nov/Dec 2008
  • RV Sonne, SO202.2 (TransBrom-Sonne), Kushiro (Japan) to Townsville (Australia), Oct 2009
  • RV Polarstern, ANT XXVI-4, Punta Arenas to Bremerhaven, Apr/May 2010
  • RV Polarstern, ARK XXV-1, Greenland Sea, Bremerhaven to Longyearbyen (Norway) in June 2010
  • RV Poseidon, P399, Mindelo (Cap Verde) via Las Palmas (Spain) to Vigo (Spain), June 2010
  • RV Polarstern, ARK XXV-2, Fram Strait, from Lonyearbyen (Norway) to Reykjavik in June/July 2010
  • RV Maria S. Merian, MSM 18-3, Central equatorial Atlantic, Mindelo to Libreville (Gambia), Jun-Jul 2011
  • RV Polarstern, ARK XXVI-3, Transarc, Tromsö (Norway) to Bremerhaven,  Aug-Oct 2011
  • RV Sonne, SO218 (SHIVA-Sonne), Singapore to Manila (Phillipines), Nov 2011
  • RV Polarstern, ANTXXVIII-3, Southern Atlantic Cruise; Capetown-Punta Arenas, Jan-Mar 2012
  • RV Meteor,  M91, Peru Upwelling, Callao (Peru)  to Callao, Dec 2012
  • Alfacs Bay 2013, Delta del Ebro (Spain), Jun 2013
  • Lena Delta 2013, Tiksi (Russia), Sep 2013
  • Alfacs Bay 2014, Delta del Ebro, Mar 2014, Phytoscope project with CSIC
  • RV Polarstern, ARKXXVIII-1/2 , Fram Strait, Bremerhaven-Tromsö; 6 Jun-3 Jul 2014
  • SHIVASonne SO235 (OASIS-2), Indic Ocean, Port Luis (Mauritius) to Male (Malediven), Jul to Aug 2014
  • RV Polarstern, ARK XXIX-2.2 (PS93.2), Fram Strait, Tromsö to Tromsö, Jul-Aug 2015
  • RV SONNE, SO243 (ASTRA), Guayaquil (Equador) to Antofagasta (Chile), Oct 2015
  • RVHeincke, He462, North Sea, Bremerhaven to Sogne Fjord and back, Apr-May 2016
  • RV Polarstern, PS99, Fram Strait, Bremerhaven to Tromsö, Jun-Jul 2016
  • RV Polarstern, PS103, Atlantic Southern Ocean, Capetown to Punta Arenas, Dec 2016-Feb 2017
  • RV Polarstern, PS107, Fram Strait, Tromsö to Tromsö, Jul-Aug 2017
  • RV Polarstern, PS113, Atlantc Ocean, Punta Arenas-Bremerhaven, May-Jun 2018
  • RVHeincke, He535, North Sea, Bremerhaven to Hegoland, Jun 2019
  • RV Polarstern, PS121, Fram Strait, Bremerhaven to Tromsö, Aug-Sep 2019
  • RV Kormoran, BS1, Lake Constance, Langenargen to Langenargen, Mar 2020
  • RV Maria S. Merian, MSM 93, Fram Strait, Bremerhaven to Bremerhaven, Jun-Jul 2020
  • RV Kormoran, BS2, Lake Constance, Langenargen to Langenargen, Aug/Sep 2020

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.,

Christian Hohe                                 Sonja Wiegmann

Mariana Soppa          Prof. Dr. Astrid Bracher

Continuous measurements of IOPs at surface water during expedition ARKXXIX-2.2

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.