Scientific cruise report Elisabeth Mann-Borgese SUMMIX-MESO

Objectives: It was intended to investigate the meso-scale and sub-meso-scale dynamics of the upper layers (upper 80 m) in the central Baltic Sea, using towed instruments and acoustic profilers, to better understand the physical conditions for cyanobacteria blooms. Under optimal weather conditions, we intended to carry out 10 one-day quasi-synoptic surveys by cruising in large meandering patterns (see fig. 1) covering areas of 15 X 15 nautical miles or 8 X 8 nautical miles, depending on the survey mode, see below. This cruise was the meso-scale component of the two-ship SUMMIX experiment together with RV Meteor (Physical and biochemical exchange-, mixing- and transformation processes in the central Baltic Sea during summer stratification and their controls on the cyanobacterial summer bloom) which was intended to be located at a fixed position nearby RV Elisabeth Mann Borgese in order to survey the water column in high vertical, spatial and parameter resolution, including biogeochemical experiments on board. In addition to the physical parameters, also vertical and horizontal zooplankton net tows as well as water samples taken by CTD bottles were planned

ADCP current measurements (75 kHz working area dataset) during RV MARIA S. MERIAN cruise MSM105

Upper-ocean velocities along the cruise track of RV MARIA S. MERIAN cruise MSM105 were continuously collected by a vessel-mounted Teledyne RD Instruments 75 kHz Ocean Surveyor ADCP. The transducer was located at 6.0 m below the water line. The instrument was operated in broadband mode with 8 m bins and a blanking distance of 8.0 m, while 100 bins were recorded using a pulse of 0.82 s. The ship's velocity was calculated from position fixes obtained by the Global Positioning System (GPS). Heading, pitch and roll data from the ship's gyro platforms and the navigation data were used by the data acquisition software VmDas internally to convert ADCP velocities into earth coordinates. 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 (0.78° +/- 0.6410°) and scale factor (1.0089 +/- 0.0146) of the Ocean Surveyor signal. The average interval was set to 60 s

ADCP current measurements (75 kHz transit dataset) during RV MARIA S. MERIAN cruise MSM105

Upper-ocean velocities along the cruise track of RV MARIA S. MERIAN cruise MSM105 were continuously collected by a vessel-mounted Teledyne RD Instruments 75 kHz Ocean Surveyor ADCP. The transducer was located at 6.0 m below the water line. The instrument was operated in broadband mode with 8 m bins and a blanking distance of 8.0 m, while 100 bins were recorded using a pulse of 0.82 s. The ship's velocity was calculated from position fixes obtained by the Global Positioning System (GPS). Heading, pitch and roll data from the ship's gyro platforms and the navigation data were used by the data acquisition software VmDas internally to convert ADCP velocities into earth coordinates. 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 (0.78° +/- 0.6410°) and scale factor (1.0089 +/- 0.0146) of the Ocean Surveyor signal. The average interval was set to 60 s

Hydrographic properties of water masses in the Amazonas River plume obtained in April/May 2021 by CTD measurements during RV METEOR cruise M174

As result of population growth and human development, many low latitude river-ocean systems are undergoing fundamental changes. The RV METEOR cruise M174 (https://doi.org/10.1594/PANGAEA.935041) was dedicated to understanding the links between the Amazon River and the adjacent tropical ocean, which are critical components of any attempt to address the ecosystem's health and productivity. This CTD dataset covers the Amazon River plume on the Brazilian shelf, the shelf of French Guinea and the adjacent offshore area as an example for such ecosystems. The data set has been obtained with a CTD SBE 911plus in April and May 2021, and contains vertical profiles of pressure, temperature, practical salinity, dissolved oxygen concentration, turbidity, and nitrate concentration

Evidence for a warm water inflow into the Baltic Proper in summer 2003

The exceptional warm water inflow into the Baltic Sea in summer 2002, which preceded the major Baltic inflow of January 2003, was surprisingly repeated in modified form in summer 2003. Its warm waters even replaced the renewed, cold inflow waters in the eastern Gotland Basin and commenced another warm period in its deep layers, where the previous one had lasted from 1997 to 2003. Details of the temporal and spatial behaviour of this new baroclinic inflow are presented from various measurements carried out from the Kiel Bight up to Gotland, covering the Darss Sill, the Arkona, Bornholm, Gdañsk Basins and the S³upsk Channel, focused mainly on the time period between July 2003 and July 2004. Hypothetically, the repetition of these exceptional warm inflow events could be regarded as a possible regional indicator for global climatic change