Oceanographic data resources

oceans and hold tremendous promise for acquiring data to address critical questions for the Southern Ocean. Because of the problem of ice damage to floats and drifters, novel technologies and techniques have been developed to cope with these conditions, e.g. in the case of Argo, experimenting with subsurface tracking using Sound Fixing and Ranging (SOFAR) technology, storage of the profiles, and the adaptation of software to detect ice as the float attempts to surface to transmit its data to satellite (e.g. Klatt et al., 2007). The installation of arrays of sound sources to be used by floats and gliders are a logistical and financial challenge. The application of ice-tethered platforms consisting of autonomous surface platforms on the ice with profiling instruments under the ice which are now common in the Arctic is restricted in the Antarctic due to the almost completely disappearing sea ice in summer.

Figure 2.11 Tracks of elephant seals tagged with instruments to record temperature and salinity profiles in the Southern Ocean (source Biuw et al., 2007).

2.1.3.6 Sensors on animals

The use of innovative techniques, such as the deployment of small sensors on wide-ranging marine animals (Figure 2.11) has provided a wealth of data on their movements and behaviour as well as providing near real-time monitoring of ocean properties for long-term weather and climate analyses and forecasting (e.g. Biuw et al., 2007).

2.1.3.7 Oceanographic data resources

In order to facilitate international exchange of scientific data a number of oceanographic data centres have been set up both as access points and repositories for such data. As well as National Data Centres there exist a number of international Data Assembly Centres that are dedicated to the collation, archival and delivery of data and products (see e.g.

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and Variability Project) and Carbon Hydrographic Data Office is a repository and distribution centre for CTD and Hydrographic data sets act to facilitate data exchange as well as providing access to the data itself, for example the World Data Center for Oceanography , the IOC’s International Oceanographic Data and Information Exchange (IODE) Joint Committee for Antarctic Data Management (JCADM; http://www.jcadm.scar.org/).

A number of other resources exist for oceanographic data, for example the online Southern Ocean Atlas region south of 30°S (e.g. Figure 2.12). Static atlas products are available for browsing and downloading, but a suite of fully interactive tools are also provided where users can construct atlas illustrations using their own choice of parameters.

Figure 2.12 Example figure produced using the Southern Ocean Atlas data. Red dots are CTD data only.

Southern Ocean READER is a portal for links to temperature, salinity and ocean current data from the Southern Ocean (http://www.antarctica.ac.uk/met/SCAR_ssg_ps/OceanREADER/).

The Joint World Meteorological Organisation Intergovernmental Oceanographic Commission Technical Commission for Oceanography and Marine Meteorology in situ Observing Platform Support Centre (JCOMMOPS) provides coordination at the international level for oceanographic and marine observations from drifting buoys, moored buoys in the high seas, ships of opportunity and sub-surface profiling floats see Figure 2.13).

2.1.3.8 Observational problems

There is a suite of methods available to study the Southern Ocean. However, despite the importance of the region to global change, it is still one of the most data-sparse regions on the planet.

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Figure 2.13a Observations available in the Southern Ocean region from JCOMMOPS (as of February 2008).

Figure 2.13b Sub-surface profiles available in the Southern Ocean region from JCOMMOPS (as of February 2008).

Currently we are not able to routinely monitor the characteristics of the ocean in the seasonally and permanently ice-covered region, which covers an area the size of Antarctica itself during the southern winter months. This is despite the efforts of extending Argo to the sea ice zone, the use of ice-tethered profilers and the inclusion of sensors on marine mammals that forage under the ice. Argo is currently also limited to the upper 2,000 m. In order to properly understand the processes that contribute to global change (e.g. understanding the overturning circulation) our monitoring efforts need to be extended to the deep ocean.

Measurements in the ice shelf environment, especially in the ice cavity regions beneath the ice shelves, are particularly difficult. Routine sustained monitoring is virtually unknown, but is required to understand how the ocean/ice shelf interaction will change as the climate alters, and what the impacts are for deep and bottom water formation and the global overturning in the ocean.

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Because of the unique problems encountered at high latitudes, development of new sensors and methodologies is key, for example the addition of biogeochemistry sensors to Argo floats, or technology to study the long-term impact of seasonal ice cover on pelagic and benthic communities.

It is imperative to sample the polar oceans routinely and cost-effectively with an appropriate level of coverage to capture the main oceanographic and marine meteorological processes taking place that contribute to global change.

During the International Polar Year 2007-2008 - and beyond – one of the key aims is to monitor the Southern Ocean in a sustained manner (e.g. Summerhayes et al., 2007). This is already underway with the development of a Southern Ocean Observing System (e.g.

Sparrow, 2007) that will incorporate the whole range of observations available to observe the marine physics and surface atmosphere, biogeochemistry and carbon, cryosphere and sea ice of the Southern Ocean.