Description: Current velocities of the upper water column along the cruise track of R/V Meteor III cruise MET187 were collected by a vessel-mounted 38 kHz RDI Ocean Surveyor ADCP. The ADCP transducer was located at 5.0 m below the water line. The instrument was operated in narrowband mode (WM10) with a bin size of 16.00 m, a blanking distance of 16.00 m, and a total of 100 bins, covering the depth range between 37.0 m and 1621.0 m. Heading, pitch and roll data from the ship's motion reference unit and the navigation data from the Global Positioning systems were used by the data acquisition software VmDAS internally to convert ADCP velocities into earth coordinates. Measured velocities and bin-depth mapping were corrected due to occasional incorrect temperature measurements at the transducer that affected the sound velocity calculation. Corrected sound velocity values were derived using temperature measured by the ship's thermosalinograph. Single-ping data / ping ensembles were screened for bottom signals and, where appropriate, a bottom mask was manually processed. The ship's velocity was calculated from position fixes obtained by the Global Positioning System (GPS). Accuracy of the ADCP velocities mainly depends on the quality of the position fixes and the ship's heading data. Further errors stem from a misalignment of the transducer with the ship's centerline. Data post-processing included water track calibration of the misalignment angle (-44.8220° +/- 0.6351°) and scale factor (1.0046 +/- 0.0109) of the Ocean Surveyor signal. The velocity data were averaged in time using an average interval of 60 s. Velocity quality flagging is based on following threshold criteria: abs(UC) or abs(VC) 〉 1.5 m/s, rms(UC_z) or rms(VC_z) 〉 0.3.

Description: Current velocities of the upper water column along the cruise track of R/V Meteor III cruise MET187 were collected by a vessel-mounted 75 kHz RDI Workhorse Long Ranger ADCP. The ADCP transducer was located at 5.0 m below the water line. The instrument was operated in broadband mode (WM1) with two different configurations: (1 - corresponding to met_187_vmadcp_75khz_01.nc) bin size: 5.0 m, blanking distance: 2.0 m, number of bins: 128, vertical range: 12.0 m - 647.0 m; (2 - corresponding to met_187_vmadcp_75khz_0[2,3].nc) bin size: 8.0 m, blanking distance: 4.0 m, number of bins: 100, vertical range: 17.0 - 809.0 m. Heading, pitch and roll data from the ship's motion reference unit and the navigation data from the Global Positioning systems were used by the data acquisition software VmDAS internally to convert ADCP velocities into earth coordinates. Single-ping data / ping ensembles were screened for bottom signals and, where appropriate, a bottom mask was manually processed. The ship's velocity was calculated from position fixes obtained by the Global Positioning System (GPS). Accuracy of the ADCP velocities mainly depends on the quality of the position fixes and the ship's heading data. Further errors stem from a misalignment of the transducer with the ship's centerline. For technical reasons, the transducer was lifted from the moonpool on February 18th, 2023. Therefore, two separate calibrations were carried out: Data post-processing included water track calibration of the misalignment angle and scale factor of the Ocean Surveyor signal. For technical reasons, the transducer was lifted from the moonpool on February 18th, 2023. Therefore, two separate calibrations were carried out: prior February 18th, 2023 (corresponding to met_187_vmadcp_75khz_0[1,2].nc): misalignment angle of -41.8717° +/- 0.4333° (0.5755°), scale factor of 1.0001 +/- 0.0064 (0.0079); after February 18th, 2023 (corresponding to met_187_vmadcp_75khz_03.nc): misalignment angle of -41.8071° +/- 0.5600°, scale factor of 0.9971 +/- 0.0074. The velocity data were averaged in time using an average interval of 60 s. Velocity quality flagging is based on following threshold criteria: abs(UC) or abs(VC) 〉 1.5 m/s, rms(UC_z) or rms(VC_z) 〉 0.3.

Description: Underway chlorophyll-a and turbidity data were acquired during the SO287-CONNECT cruise on board the German Research Vessel SONNE. A detailed report describes the processing procedures, including scientific visualization and tabulation of the datasets. The SO287-CONNECT oceanographic campaign aimed to cross the North Atlantic Ocean from Las Palmas (Gran Canaria, Spain) to Guayaquil (Ecuador, in the Equatorial Pacific Ocean) between 11 December 2021 and 11 January 2022.

Description: The transit of RV SONNE from Las Palmas (departure: 11.12.2021) to Guayaquil, Ecuador (arrival: 11.01.2022) is directly related to the international collaborative project SO287-CONNECT of GEOMAR in cooperation with Hereon and the University of Bremen, supported by the German Federal Ministry of Education and Research (BMBF) between October 15 2021 and January 15 2024. The research expedition was conducted to decipher the coupling of biogeochemical and ecological processes and their influence on atmospheric chemistry along the transport pathway of water from the upwelling zones off Africa into the Sargasso Sea and further to the Caribbean and the equatorial Pacific. Nutrient-rich water rises from the deep and promotes the growth of plant and animal microorganisms, and fish at the ocean surface off West Africa. The North Equatorial Current water carries the water from the upwelling, which contains large amounts of organic material across the Atlantic to the Caribbean, supporting bacterial activity along the way. But how the nutritious remnants of algae and other substances are processed on their long journey, biochemically transformed, decomposed into nutrients and respired to carbon dioxide, has so far only been partially investigated. Air, seawater and particles were sampled in order to provide new details about the large cycles of carbon and nitrogen, but also of many other elements such as oxygen, iodine, bromine and sulfur. Inorganic and organic bromine and iodine compounds are generally emitted naturally from the ocean into the atmosphere, promote cloud formation and affect climate, and some even reach the stratosphere where they contribute to ozone depletion. We measured how much of these compounds are released from the ocean, and at what locations and how they are transformed in the ocean and in the atmosphere. Sargassum algae, which have become a nuisance on beaches in the western and eastern Atlantic, support life and contribute to carbon cycling in the middle of the Atlantic, the Sargasso Sea and in the Caribbean, while their contribution to halogen cycling and marine bromine and iodine emissions was previously unknown. We investigated the influence of various natural parameters such as temperature and solar radiation on the biogeochemical transformation processes in order to understand the influence of climate change on these processes in incubation experiments with seawater and algae. We investigated how anthropogenic signals such as shipping traffic influence the nitrogen and sulphur cycle in the ocean, as well as the impact of nitrogen oxides from ship exhaust and sulphurous, acidic and dirty water from purification systems on organisms and biochemical processes. Plastic debris was sampled from the surface waters to investigate its contribution to global biogeochemical transformation processes. The working hypotheses of the research program were:  Bioavailability of dissolved organic carbon in surface waters decreases along the productivity gradient and transport pathway from the Eastern to the Western Tropical North Atlantic.  Nutrient gradients from East to West constrain the microbial utilization of organic matter- contributing to an accumulation of C-rich organic matter due to a) limited mineralization and b) enhanced exudation- also leading to gel-like particles accumulation in the western tropical North Atlantic and Sargasso Sea.  Tropospheric and stratospheric ozone are strongly impacted by biogeochemical and ecological processes occurring around and in the NA gyre system related to marine iodine and bromine cycles.  The long-range transport of natural and anthropogenic organic matter in water and of gases and aerosols in the air impact carbon-export, biogeochemical cycles in the water column, and the release of gases and particles from the ocean significantly. 4 SONNE -Berichte, SO287, Las Palmas - Guayaquil, 11.12.2021 - 11.01.202 The data and samples obtained specifically target carbon, nutrient and halogen cycling, the composition of phytoplankton, bacteria, the transport and sequestration of macro algae and the air-sea exchange processes of climate relevant gases and aerosols. The influence of ecological and transport processes, as well as anthropogenic impacts on the North Atlantic gyre system, specifically in the Sargasso Sea and the influence of ship emissions throughout the Atlantic towards the west and into the Pacific will be investigated with the data.

Description: Deep-ocean islands have long been associated with the generation of oceanic eddies in their wakes. However, their interaction with incoming eddies has seldom been considered. This study focuses on the characterization of background and locally generated mesoscale eddies in the Cabo Verde archipelago between 2003 and 2014. Special attention is given to the interaction of incoming eddies with the bathymetry of the islands, along with their impacts on the local generation of eddies. Island-induced wind-shear effects are also considered. In addition, some examples of the biological response to background and locally generated eddies are discussed. This is achieved by combining remote-sensing satellite observations for wind, sea surface height, and chlorophyll-a (Chla) surface concentrations. The results show that the interaction between incoming background eddies and the archipelago is a recurrent phenomenon, which results in eddy deflection, splitting, merging, intensification, and termination (sorted by highest to lowest number of occurrences). Local island-induced disturbances are also significant, mainly due to atmospheric effects. Such processes result in the generation of island-induced eddies and in wind-mediated eddy intensification and confinement, more often observed in the leeward group. Nonetheless, it is strongly suggested that many of the locally generated eddies are a direct product or by-product of the interaction of background eddies with the islands. With respect to the biological realm, a locally generated cyclonic eddy is observed to originate a pronounced phytoplankton bloom in the vicinity of the tallest island. Nonetheless, background eddies generated off the African coast are often associated with enhanced Chla concentrations when they intersect the archipelago. Such observations challenge the idea that local biological productivity in deep oceanic islands is exclusively driven by island-induced mechanisms.