During RV METEOR cruise M148-2 in the Angola Gyre as well as the Benguela Upwelling System off the coast of Namibia water samples were taken from surface waters, deep chlorophyll maximum zone (DCM), oxygen depleted zone underneath the DCM and deeper waters. Here, we report the absorbance measurements of coloured dissolved organic matter (CDOM) that were conducted immediately after collection from the CTD rosette on board RV METEOR. The collected water samples were poured into 250 ml Schott glass bottles covered in aluminium foil creating dark containers. These glass bottles were left to reach room temperature for about 30 to 60 minutes. Filtration was completed using 25 mm Nuclepore syringe filters with pore sizes of 0.2 µm directly into a 10 cm quartz cuvette. This cuvette had been pre-rinsed three times with the sample before measurement (Garaba et al., 2014). A Shimadzu UV2700 spectrophotometer was used to determine the absorbance of the filtered samples over a wavelength range from 200 to 800 nm in 5 nm steps and Milli-Q was used as a reference. The provided dataset contains the raw absorption units averaged out of three measurements per sample.

We would like to thank RV Captain Detlef Korte and crew for supporting our research activities aboard RV METEOR during cruise M148/2. We are grateful of all the shore-based technicians, administrative personnel and scientists involved in the cruise. The German Federal Ministry of Education and Research (BMBF), Meteor Leitstelle, German National Science Foundation (DFG), Max Planck Society contributed towards the organization and funding of Meteor Expedition M148/2 EreBUS: Processes Controlling Greenhouse Gas Emissions from the Benguela Upwelling System.