What is IPY
In yesterday's post, we focused on phytoplankton growth in the Southern Ocean, the role of iron in limiting or favoring that growth and the importance of those Southern Ocean biological processes in the global carbon cycle. Today we explore the role of winds in the same region - the Southern Ocean - and again the importance of processes in that region for the global carbon cycle.
In a paper published 14 March 2010, oceanographers from Australia and the USA have examined processes that mix the upper ocean in the regions around Antarctica. Shallow stable mixed layers act as barriers between the atmosphere and the deep ocean, but deep mixed layers can act as gateways between the atmosphere and the interior ocean. Through strong winds and deep mixing in the Southern Oceans (oceanographers use the term 'ventilation'), heat and carbon can move from the atmosphere into the global oceans. The image below shows how deep mixing occurs in a band around Antarctica during the winter - red values indicate mixing to depths of 300 to 500 meters.
Deep mixing can have a complicated impact on Southern Ocean biological systems, and particularly on the phytoplankton. Mixing can bring up more nutrients from below, but it can also mix the plants down below the zone where they have enough light to grow. Near Antarctica, the mixing can have very different effects in summer than in winter. This paper identifies stronger winds and deeper mixed layers as a recent trend, and the authors say: "Our results suggest that changes in the [Southern Ocean wind regime], including recent and projected trends attributed to human activity, drive variations in Southern Ocean mixed-layer depth, with consequences for air–sea exchange, ocean sequestration of heat and carbon, and biological productivity." What happens at the poles affects us all!
For more information, read the original paper in Nature Geoscience or read a very nice guide and summary by Sarah Gille.
In the Southern Ocean, occasional abundant growth of tiny plants, phytoplankton, can pull CO2 from the atmosphere. When those plants sink, directly or after serving as food for larger organisms, the Southern Ocean system becomes a net carbon sink, a place where carbon leaves the atmosphere for long-term storage in ocean sediments. Thus, what happens in the Southern Ocean ecosystems affects us all.
In a paper published 14 March 2010, French and Australian researchers have used new IPY measurements of iron in the Southern Ocean (from the IPY Geotraces Project) to test and validate a new model for sources of iron in the Southern Ocean - phytoplankton depend on iron for growth. These researchers have suggested that in addition to iron delivered from above (in atmospheric dust) and from the ocean floor (in resuspended sediments), iron from hydrothermal activity on the ocean floor can increase the Southern Ocean carbon export (sinkage) by 10 to 15%, and by up to 30% in some regions of the Southern Ocean. The figure below shows a model of dissovled iron in the Pacific, with an enrichment (yellow) clearly visible in the Southern Ocean.
The authors say "Marine productivity in the Southern Ocean is limited by the availability of iron and this region is critical in governing atmospheric CO2 levels. Given its importance in controlling ocean [dissolved iron], hydrothermalism should be included in our understanding of the Southern Ocean [dissolved iron] cycle." Read more about this topic in Nature Geoscience.
In a paper in the journal Science, published on 5 March, researchers from Russia, Sweden and the USA reported their results from 5000 at-sea measurements of dissolved methane in the coastal waters off of Eastern Siberia. They showed that most of the bottom waters and more than half of the surface waters of the East Siberian Arctic Shelf contained supersaturations of methane - a supersaturation represents more methane than expected and indicates a source other than the atmosphere. They determined that the methane entered the ocean waters from below, from the large reserviors of methane and other carbon in the sub-sea permafrost.
In places, they also observed high concentrations of methane in the atmosphere, methane that had first entered the ocean and then escaped to the atmosphere - see the figure below.
Because methane becomes a global greenhouse gas, release of methane from any northern sources, the sub-sea permafrost or the land permafrost, will have global impact. What happens at the poles affects us all! The authors of this study conclude "Leakage of methane through shallow ESAS waters needs to be considered in interactions between the biogeosphere and a warming Arctic climate." Indeed!
For more information, see this USA National Science Foundation announcement. For background information, and for the source of the image used here, see this WWF Report, 'Arctic Climate Feedbacks: Global Implications'.
After a few extra days to catch some late-arriving abstracts, the abstract submission process for the IPY Oslo Science Conference has now closed. We count approximately 2600 abstracts received, presenting us with the opportunity and the challenge of organizing and conducting one of the largest and most diverse conferences in the history of polar science.
In addition to the broad spectrum of IPY research, the conference will also offer:
Hundreds of early career researchers, excited to carry forward the energy and international cooperation of this IPY;
More than one hundred teachers, each of whom has submitted an abstract, and all of whom will join the full range of talks and events;
A polar information commons, featuring many polar data centers and the new Polar Information Commons (more information soon); and
Films, books, exhibits, food and fun.
Registration has opened. Early bird registration, and favourable access to hotel accommodations, will end on 8 March 2010. The entire team of session convenors, theme chairs, and steering group members make a vigorous effort to review all the abstracts, produce a draft program, and provide a quick response to all who submitted abstracts.
For more information, see the Konferanse web site.
For a media alert, and a press release, please visit the Konferanse media page or the press page on this site.
Leaders of an Arctic System Reanalysis activity, part of the IPY Climate of the Arctic Project, have presented their plans and issued an invitation to the IPY community for evaluation and participation.
In an article published recently in EOS (Volume 91, Number 2, 12 January 2010), David Bromwich and co-authors described plans for an Arctic System Reanalysis. This activity, part of the IPY Climate of the Arctic Project, and a component of the USA SEARCH (Study of Environmental Arctic Change) program, represents an ambitious plan to draw in many IPY partners and many of the IPY observations from the Arctic. Bromwich et al. describe a low-resolution (30 km) prototype, with an inner domain shown in the image above, focused on 2007 and 2008. Eventually they intend to complete a decade-long reanalysis (2000 to 2010) at 10 km spacing and 3 hour resolution. Please visit the Arctic System Reanalysis web page.
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