Processed CO2/O2 Float data from 4 deployments near Cape Verde Island (11/2010 - 06/2011)

In recent years, profiling floats, which form the basis of the successful international Argo observatory, are also being considered as platforms for marine biogeochemical research. This study showcases the utility of floats as a novel tool for combined gas measurements of CO2 partial pressure (pCO2) and O2. These float prototypes were equipped with a small-sized and submersible pCO2 sensor and an optode O2 sensor for highresolution measurements in the surface ocean layer. Four consecutive deployments were carried out during November 2010 and June 2011 near the Cape Verde Ocean Observatory (CVOO) in the eastern tropical North Atlantic. The profiling float performed upcasts every 31 h while measuring pCO2, O2, salinity, temperature, and hydrostatic pressure in the upper 200 m of the water column. To maintain accuracy, regular pCO2 sensor zeroings at depth and surface, as well as optode measurements in air, were performed for each profile. Through the application of data processing procedures (e.g., time-lag correction), accuracies of floatborne pCO2 measurements were greatly improved (10-15 µatm for the water column and 5 µatm for surface measurements). O2 measurements yielded an accuracy of 2 µmol/kg. First results of this pilot study show the possibility of using profiling floats as a platform for detailed and unattended observations of the marine carbon and oxygen cycle dynamics.

Physical oceanography during SONNE cruise SO248 (BacGeoPac)

The data presented here were collected during the cruise SO248 (Project BacGeoPac) with the RV Sonne from Auckland, New Zealand to Dutch Harbor, Alaska/USA. The cruise lasted from May 1, 2016 to June 3, 2016 and 19 vertical CTD-hauls were conducted. The CTD system used during this cruise was a Sea-Bird Electronics Inc. SBE 911plus probe (SN 09-1266). The CTD was attached to a SBE 32 Carousel Water Sampler (SN 32-1119) containing 24 20-liter Ocean Test Equipment Inc. bottles. The system was equipped with double temperature (SBE 3) and conductivity sensors (SBE 4), a pressure sensor (Digiquartz) an oxygen (Aanderaa Optode 4831F) and, an altimeter (Bentos) and a chlorophyll fluorometer combined with a turbidity sensor (FluoroWetlabECO _AFL FL). The sensors were pre-calibrated by the manufacturers. The data were recorded with the Seasave V 7.23.2 software and processed using the SeaBird SBE Data Processing and the ManageCTD-software. The data were processed in the following way: Data obtained during adaptation of the CTD to ambient water conditions were removed manually. The "wildedit", "loopedit", "despike", "binavg" routines were applied. The data were also visually checked and a double sensor check was conducted. The accuracy of the double sensors derived from 56 data sets were: Temperature T = 0.0007 °C; Conductivity: C = 0,0071 mS/cm; Salinity S = 0.0081 psu. The salinity data (S by unsing pss78) were converted to absolute Salinity (SA) by using the TEOS 10 toolbox. The ship position data were derived from the shipboard GPS-system linked to the CTD data. The time zone is given in UTC. The oxygen CTD data were validated by additional measurements of 98 water samples using the Winkler titration method.