Particulate absorption during Maria S. Merian cruise MSM09/1

• Main Authors: Bracher, Astrid, Taylor, Bettina B
• Format: Dataset
• Language: English
• Published: PANGAEA 2021
• Subjects: absorption; Absorption coefficient; total particulate matter; at 300 nm; at 301 nm; at 302 nm; at 303 nm; at 304 nm; at 305 nm; at 306 nm; at 307 nm; at 308 nm; at 309 nm; at 310 nm; at 311 nm; at 312 nm; at 313 nm; at 314 nm; at 315 nm; Alfred Wegener Institute; Newfoundland; North Atlantic
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.937967; https://doi.org/10.1594/PANGAEA.937967

Samples for the pigment data set were collected during RV Maria S. Merian cruise MSM9/1 in July/August 2008 in the North Atlantic from Bremen, Germany to St. John's, Newfoundland, Canada (see cruise report Kucera et al. 2014). Sampling was conducted at various stations from a rosette coupled to a conductivity temperature density (CTD) profiler at three to four depths and otherwise sampling regularly every 6 to 8 hours the surface water (approx. 10 m depth) from the ship's moonpool. Water samples were filtered on GF/F filters. Filters were immediately shockfrozen in liquid nitrogen and stored at -80°C until further analysis at the laboratories of the Alfred-Wegener-Institute Helmholtz Centre for Polar and Marine Research (AWI). Measurements of the particulate absorption were carried out on a dual-beam UV/VIS spectrophotometer (Cary 4000, Varian Inc.) equipped with a 150 mm integrating sphere (external DRA-900, Varian, Inc. and Labsphere Inc., made from Spectralon (TM)) using a quantitative filterpad technique modified as follows (see e.g. Simis et al., 2005). The filters were placed in the center of the integrating sphere using a center-mount filter holder perpendicular to the light beam. A wavelength scan from 300 to 850 nm with a resolution of 1 nm (slit width 2 nm, scan rate 150 nm min−1 ) was performed, when the reflectance ports were covered with Spectralon(TM) reflectance standards. The baseline was recorded beforehand with a clean, dry filter, and a filter which was soaked for more than 30 min in purified water served as a reference. The absorption coefficient was calculated from optical density (OD) measurements using a path length amplification factor of 4.5 (β = 1/4.5, Taylor et al. 2011) as a [m−1 ] = −ln (T · A · β/V ), where the transmittance T = exp (−OD), V is the filtrated sample volume in m3 and A the filter clearance area in m2 . Results from the original filter gave particulate absorption, ap. More details on the method can be found in Taylor et al. (2011). The data set is also collocated to ...