Description: Two megameter long XBT sections passing through the Atlantic between the Iberian Peninsula and the equatorial Brazilian shelf, and between the Peninsula and the Cape region of South Africa were obtained during supply cruises to the antarctic in November 1980 and March 1981. Most of the individual probes reached an observation depth of nearly 800 m allowing statements on the thermal stratification and zonation of theWarmwassersphäre in the open ocean. Our new data are compared with a number of earlier long sections. As a general result we identify five zones dividing different hydrographic regions. Zone 1 is characterized by the clear influence of the Mediternean Undercurrent on the lower boundary of theWarmwasserphäre creating nearly thermostatic conditions below 300 m off Portugal. The adjacent zone 2 is identical with the Subtropical Convergence, where theWarmwassersphäre reaches its maximum depth (15°C isotherm at about 300 m). We call the equatorial region zone 3 and present an improved scheme of its current system and its thermal stratification. Zone 4 is marked by the Benguela Current and its northern extension. In a final zone 5 we show the influence of the Agulhas Current extension on the stratification.

Description: In this paper, different types of new data sets (hydrography, Lagrangian and Eulerian current measurements) and Quasi-Geostrophic model results, obtained after altimetric data assimilation, are used to study the structure and variability of the Azores Current and Frontal system. The Azores Current was observed to transport between 11.0 and 18.0 Sv eastwards and the associated Counter Current some 2.0–10.0 Sv to the west, resulting in a net value of about 8–9 Sv. Furthermore, both data and model results revealed a meandering Azores Current, where some freely rotating eddies were also identified. These hydrographic and Lagrangian results exhibit space and time scales that agree fairly well with the dynamics shaped by baroclinic instability. Current meters moored across the Azores Current system delineated a mean Counter Current flowing westwards with a maximum subsurface core of about 2.0 cm/s at a mean depth of 800 dbar. This is in excellent agreement with previous studies, which explains this Azores Counter Current as the rectification process of the geostrophic turbulence occurring north of the main Azores Current stream. A new scheme is proposed for the formation mechanism of the freely rotating cyclonic eddies observed south of the Azores. It is shown that the north–south contrast thickness of the 17–19°C water layer across the Azores Front decreases downstream. This will create, in turn, a downstream increase of the most unstable wavelength, in a non-linear baroclinic instability context. As a consequence, both large cyclonic and anticyclonic features are able to form at the eastern side of the Azores Current (around 19°W), while at the western side (around 35°W) only large anticyclones will survive (western-generated cyclones will be small enough to be quickly dissipated). This means that the eastern cyclones of the Azores Current may live longer than the shorter western ones. However, because longer-lived cyclonic eddies propagate westwards with a mean speed of 2.5 km/day, they may be observed south of Azores and of the main stream several months later, although they were not formed there.

Description: Measurements by CTDs (Multisonde, Bathysonde) and current profilers were carried out onboard the research vessels "Meteor" and "Planet" during the Joint Air-Sea Interaction Project (JASIN) in 1978. Data from these observations are presented in the form of mean distributions with their standard deviations, as time series and as profiles during the "multiship experiments". Selected time series of terms derived from the data are added: current shear, Vaisala frequency and Richardson Number. The text also contains information concerning instrument calibration and data processing.

Description: 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.