ALBERT

Description: The ability to monitor the heat content of oceans over long distances is becoming increasingly important for understanding the role of oceans in climate change, for determining the variability of the state of the oceans, for operational ocean observing systems, and for studying large-scale ocean processes such as water-mass formation. Although the properties of the upper layers of the ocean can be routinely measured on large scales by satellite remote sensing (providing altimetric and infrared data) and with expendable probes dropped from commercial vessels, the deep interior of the ocean is more difficult to monitor. Ocean acoustic tomography1 is a promising technique for such applications, as it has the potential to provide systematic, instantaneous and repeated measurements of the ocean interior over large parts of an ocean basin. Here we demonstrate the capability of this technique for measuring the heat content across an entire (albeit small) ocean basin—the western Mediterranean Sea.

Description: The aim of the OceanoScientific® Programme and its SolOceans One-design Class is to collect and transmit scientific data from the ocean-atmosphere interface during regularly starting offshore sailing races. Data collected on board the first SolOceans One-design proved to be of good quality. Thus the first important step towards the introduction of an accepted as well as highly valuable platform for ocean surface and atmospheric parameter acquisition has been taken. The serial production of the vessel can begin.

Description: Open-ocean deep convection is a littleunderstood process occurring in winter in remote areas under hostile observation conditions, for example, in the Labrador and Greenland Seas and near the Antarctic continent. Deep convection is a crucial link in the “Great Ocean Conveyor Belt” [Broecker, 1991], transforming poleward flowing warm surface waters through atmosphere-oceaninteraction into cold equatorward flowing water masses. Understanding its physics, interannual variations, and role in the global thermohaline circulation is an important objective of climate change research. In convection regions, drastic changes in water mass properties and distribution occur on scales of 10–100 km. These changes occur quickly and are difficult to observe with conventional oceanographic techniques. Apart from observing the development of the deep-mixed patch of homogeneous water itself, processes of interest are convective plumes on scales 〈1 km and vertical velocities of several cm s−1 [Schott et al., 1994] that quickly mix water masses vertically, and instability processes at the rim of the convection region that expedite horizontal exchanges of convected and background water masses [e.g., Gascard, 1978].

Description: The aim of the OceanoScientific® Programme and its SolOceans One-design Class is to collect and transmit scientific data from the ocean-atmosphere interface during regularly starting offshore sailing races. Data collected on board the first vessel proved to be of good quality. Thus the first important step towards the introduction of an accepted as well as highly valuable platform for ocean surface and atmospheric parameter acquisition has been taken and its serial production can begin

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.