Ocean Science

The Mediterranean Sea is a semi-enclosed ocean basin composed of several sub-basins separated by straits and channels with depths ranging from a few hundred meters to more than 4000 m. The Mediterranean has an active deep overturning circulation that is sensitive to atmospheric forcing, atmospheric signals and changes in water mass properties can be transported to deep waters on a short time-scale. The Mediterranean Sea has an interesting oceanography with regard to physical, biological and chemical parameters and processes.

During April of 2011, a 3 week long cruise on the German research vessel Meteor (cruise M84/3) conducted a multidisciplinary investigation covering the whole Mediterranean Sea and all of its sub-basins. The cruise was set-up to follow the demands and requirements of repeat hydrography as specified by the GO-SHIP group with the goal to follow the cruise track of previous Meteor cruise through the eastern Mediterranean and a track through the western Mediterranean that has been sampled regularly. Almost simultaneously to the Meteor cruise, two other cruises were conducted in the Mediterranean Sea, on the German R/V Poseidon and on the Italian R/V Urania. These three cruises were conducted in a coordinated way with the main goals to:

• Acquire data for a (nearly) synoptic picture of distribution of chemical, physical and biological properties across the whole Mediterranean Sea, including all major sub-basins.
• Use these physical and chemical data to determine changes in circulation and ventilation and to quantify changes in inventory and distribution of properties, particularly inorganic carbon, i.e. uptake of anthropogenic carbon.
• Fill in existing gaps in the knowledge of the carbonate system of the Mediterranean Sea, including its sub-basins. More accurate estimates of anthropogenic carbon will be made and the storage rate of carbon will be quantified.

This special issue welcomes contributions on all aspects of chemical, physical and biological oceanography of the Mediterranean Sea. Results from the three nearly synoptic cruises in spring of 2011 will be reported in this special issue. However, this special issue is open for contributions covering other projects within the Mediterranean Sea.

MyOcean is a three-year european project (2009-2012) developed under the GMES umbrella, which aims at the implementation of a service dedicated to the provision of the core marine information requested by users from different marine sectors. This core ocean information is obtained by combination of observations, modelling and assimilation systems. The area of interest identified in MyOcean cover a wide range of applications of the marine field itself but also of connected fields, such as climate research and forecasting, fisheries and fish farming, merchant shipping, safety and security at sea, environmental protection and regulations, coastal areas monitoring, recreational activities, off-shore activities, defense. The essential variables required to depict the ocean state for these downstream applications include: temperature, salinity, currents, sea level, ice coverage and thickness, nutrients, primary ecosystem variables, etc. MyOcean is committed to provide this core information for the daily state of the ocean (real-time), its short-term evolution, and its history over the past (hindcast and reanalysis). The MyOcean special issue presents a selection of scientific achievements obtained as part of the Research and Development activities carried out to sustain the MyOcean project. We welcome papers discussing MyOcean modelling and data assimilation developments, MyOcean operational systems and products, validation studies, scientific diagnostics and applications. For a reminder of the themes and objectives of MyOcean please visit the web page http://www.myocean.eu.org.

Developing Arctic Modelling and Observing Capabilities for Long-term Environmental Studies (DAMOCLES) was the flagship EU project for the IPY. It concerned 47 partners from about 10 European Countries and triggered an active international scientific cooperation with Russia, China, Japan and the USA. At the time the DAMOCLES contract ended about one year ago, more than 150 scientific papers appeared in peer-reviewed publications under DAMOCLES. There are more publications to come as evidenced during the final General Assembly of Damocles in Tromsø, Norway in May 2010. During this final GA it was agreed and decided that DAMOCLES should find an appropriate scientific journal to release an important set of publications based on 6 synthetic papers and up to 30 topical papers. After some investigation it was decided to contact the European Geosciences Union Copernicus Publications to check the adequacy for submitting Damocles results dedicated to Ocean, Atmosphere and Sea Ice sciences in three Copernicus relevant journals: Atmospheric Chemistry and Physics (ACP), The Cryosphere (TC) and Ocean Science (OS).

Clouds constitute one of the major uncertainties in understanding the climate system and changes in the clouds as a consequence of global climate change is not well constrained by observations. This is particularly true in the Arctic, where clouds constitute the larges single factor affecting the surface energy balance, and therefore on melting and freezing of sea ice.

ASCOS is a highly interdisciplinary project with a major field experiment in the central Arctic Ocean during August/September 2008, approximately at 87N and 7W, deployed on the Swedish icebreaker Oden as a part of the International Polar Year (IPY). The ASCOS main target is to study the formation and life cycle of Arctic summer low-level clouds. To achieve this we deployed instruments for process level observations in a column from 0.5 km in to the ocean, through the ocean/ice surface up through the atmospheric boundary layer, and to the top of the troposphere (also see http://www.ascos.se). ASCOS measurements range from in-situ observations, to surface-based remote sensing, to airborne observations. The most intense observations were during a 3-week ice drift, starting with typical Arctic summer melt conditions and ending with the initial freeze-up of autumn. ASCOS was also coordinated with the Arctic Mechanisms of Interaction between the Surface and Atmosphere (AMISA) project, providing airborne measurements from the NASA DC8 research aircraft in the vicinity of the ASCOS column, flying in from Kiruna, Sweden.

The science team on Oden consisted of 33 researchers from 14 institutes in 11 different countries; many more are involved in analysis and associated modelling studies. This, and the experimental set-up, makes ASCOS the most extensive atmosphere-oriented experiment in the central Arctic for the entire IPY. ASCOS science cuts across several disciplines, with links to microbial life in ocean and ice, atmospheric chemistry and physics, cloud microphysics, turbulent exchange at the surfaces above and below the ice, and atmospheric circulation. A large part of ASCOS (atmospheric gas and particulate chemistry, aerosol physics, boundary-layer and synoptic meteorology) fall within the remit of ACP while physical oceanography and marine biology/chemistry fall within the remit of OS which is the incentive for a joint ACP/OS issue; only this way will it become possible to develop a special issue spanning the whole width of the science in ASCOS.

The Southern Ocean (SO) not only constitutes a geographical link between the world ocean basins, but also is a very active climate sub-system in terms of air-sea exchanges, water mass formation and transformation and biogeochemical processes and budgets. Its role in climate is central and its sensitivity to climate change is shown to be extremely important. For example, the Southern Ocean is a major CO2 sink via dynamical processes such as convection/subduction and biological carbon pumping through the export of particulate organic matter.

Prior to 1990, SO observations were sparse. Since then, an intense monitoring effort has been undertaken for two of the three SO choke points, Drake Passage and south of Australia. The one south of Africa, which is the largest, has been undersampled despite its suspected importance in the Meridional Overturning Circulation (MOC). There, the SO plays a unique role in providing the export channel for North Atlantic Deep Water to the global ocean and by importing heat, salt and biogeochemical tracers from the Indian and Pacific oceans. This region is influenced by the largest turbulence ever observed and by very efficient air-sea exchanges. Here the atmosphere and ocean are equally dynamic: the complex fronts, eddies and filaments in the ocean are analogous to the rapid frontal movements, storm passages, and dry air intrusions in the atmosphere. Transfer of heat to the atmosphere from the ocean north of the polar front contributes to the dominance of cumuliform cloud types in this region. These local small-scale processes and the derived meridional fluxes constitute the major link between the Atlantic and the other ocean basins.

The BONUS-GoodHope (BGH) project is based on a multi-disciplinary oceanographic cruise that took place during the International Polar Year (13 February – 22 March 2008) sailing from Cape Town, South Africa, to 57°S along the Greenwich Meridian in the Southern Ocean. BGH is part of an international effort on ocean exploration on the regional scale (polar regions, IPY) and on the global scale (IMBER, GEOTRACES) and has three main objectives:

• Understanding of large scale inter-ocean exchanges between the Indian, Atlantic and Southern oceans;
• Characterising the biogeochemical processes involved in the internal cycling of carbon, trace elements and isotopes;
• Assessing the impact of coastal-open ocean exchanges on geochemical properties of the water-column and biogeochemical cycles.

During BGH, observations on ocean and atmosphere dynamics were coupled with biogeochemical observations covering the full water column, with particular focus on transfer pathways of trace elements and isotopes from atmosphere to seafloor. Significant progress was achieved toward a synthetic understanding of physical, geochemical and biological processes as well as air-sea and inter-ocean exchanges, The special BG-OS issue will integrate a collection of papers presenting these achievements.

The VAMOS Ocean-Cloud-Atmosphere-Land Study (VOCALS) is an international CLIVAR/VAMOS program designed to develop and promote scientific activities leading to improved understanding, model simulations, and predictions of the southeastern Pacific (SEP) coupled ocean-atmosphere-land system, on diurnal to interannual timescales. The major components of VOCALS are a modeling program with a model hierarchy ranging from the local to global scales, a major international field program (The VOCALS Regional Experiment, VOCALS-REx), and a suite of extended observations from regular research cruises, instrumented moorings, and satellites. The combination of intensive field measurements, long-term observations, and modeling will provide important insights that will directly benefit climate modeling. Some 200 scientists from 40 institutions in 8 nations are currently participating in VOCALS. Details of the three main components of VOCALS are given below.

The SEP climate is a tightly coupled system involving poorly understood interactions between clouds, aerosols, marine boundary layer (MBL) processes, upper ocean dynamics and thermodynamics, coastal currents and upwelling, large-scale subsidence, and regional diurnal circulations, to the west of the Andes mountain range.

Further information on VOCALS can be found on the program website http://www.eol.ucar.edu/projects/vocals.

The SASSI special issue presents results from the Synoptic Antarctic Shelf-Slope Interactions (SASSI) project, coordinated by iAnZone as a contribution to the International Polar Year. We welcome papers discussing SASSI data, synthesis, historical data comparisons, or using numerical models, theory or other data sets to explain SASSI processes. Although we expect the majority of papers to be climate/iAnZone related, we welcome biological, chemical or multidisciplinary papers on shelf-slope interaction processes on or close to the Antarctic continental shelf or slope. For a reminder of SASSI themes and objectives please see http://sassi.tamu.edu.

Since the adoption of the 1978 Practical Salinity Scale (PSS-78) and the 1980 International Equation of State of Seawater about three decades ago, only slow scientific progress was made on understanding the thermophysical properties of IAPSO Standard Seawater, handling regional seawater composition anomalies, or characterizing the thermodynamic properties of seawater in contact with ice or humid air. Meanwhile, the subsequent introduction of new international standards such as the temperature scale ITS-90 or the pure-water description IAPWS-95 had not been incorporated into official oceanographic standards.

Recognising the need for a revised international standard on seawater properties, the Scientific Committee on Oceanic Research (SCOR) and the International Association for the Physical Sciences of the Oceans (IAPSO) established Working Group 127. This SCOR/IAPSO Working Group soon started a close cooperation with the International Association for the Properties of Water and Steam (IAPWS). On the occasion of the IAPWS 2008 International Conference in Berlin, the Special Issue "Thermophysical Properties of Seawater" of Ocean Science was established as a peer-reviewed and open-access resource for the wide range of scientific results produced by the work of WG 127, as well as by the IAPWS Subcommittee on Seawater.

The Special Issue now offers a comprehensive collection of background papers covering the new seawater standard, the "International Thermodynamic Equation of Seawater - 2010", TEOS-10, as well as new seawater experiments and observations, new equations of state, TEOS-10 source code, new description methods for oceanic salinity and a metrological assessment of the long-term stability of state-of-the-art salinity measurements. Additional material, including updates of equations or code published in this Special Issue, is freely available from the web pages www.TEOS-10.org and www.iapws.org and should be also consulted by interested readers of the Special Issue.