Optical instrumentation

 used for ground-truthing, algorithm development and continuous data acquisition of biogeochemical properties:

HPLC:  After filtration of water samples they are analysed by High Performance Liquid Chromatography Technique (HPLC) following Taylor et al. (2011) to obtain the concentrations of most phytoplankton pigments. The data are often further processed to obtain the chlorophyll-a concentration of various phytoplankton groups (e.g., Taylor et al. 2011, Soppa et al 2014, Cheah et al. 2017, Losa et al. 2017, Schlundt et al. 2017).

LWCC: colored dissolved organic matter (CDOM) absorption is determined with the liquid waveguide capillary cell system (LWCC, WPI) following Lefering et al. (2016).

QFT-ICAM: We determine the particulate and phytoplankton absorption coefficients with the portable quantitative filter technique (QFT) integrating cavity setup after Röttgers et al. (2016), see also Liu et al. 2018, Liu et al. 2019.

Wetlabs (Seabird) AC-s: This spectrophometer is used to measure the inherent optical properties (IOPs) of total and particle hyperspectral absorption and beam attenuation operated continuously (details see Liu et al. 2018, Liu et al. 2019).

TRIOS RAMSES: these radiometers used to measure hyperspectral downwelling above and in water irradiance and upwelling radiance above and in water operated continuously by in water profiling at discrete stations (Taylor et al. 2011, Bracher et al. 2015, Goncalves-Araujo et al. 2018, Bracher et al. 2020, Tilstone et al. 2020) and within a whole transect when mounted to the TRIAXUS platform (Bracher et al. 2020) or above water from the ship or a fixed platform (Theis 2009, Tilstone et al. 2020). Data are then further processed to obtain the  apparent optical properties (AOPs) reflectance, remote sensing reflectance (water leaving radiance) and diffuse attenuation.