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HIGH-PERFORMANCE COMPUTING


Products in brief


CREC cooling system A technique pioneered by EcoCooling and described as ‘using the building as an air- handler’ has been demonstrated to free up space for an additional 200 revenue-generating racks in a typical 1,000-rack large data centre – while cutting the energy requirement for cooling from more than 1,700kW to a mere 160kW.


InfiniteStorage 5600 Technical computing company SGI has introduced its InfiniteStorage 5600 product – a next- generation, high-performance storage platform suited to high-performance computing and Big Data workloads. Using modular architecture, SGI says the IS5600 delivers industry-leading performance.


ARM-as-a-Service Boston has unveiled its ARM-as-a- Service (AaaS), powered by Breeze and ARM, at CeBIT 2013. The Boston AaaS is hailed as the world’s first commercially available cloud offerings based on the Calxeda EnergyCore ARM-based processor technology.


DXi6800 Quantum, a provider of data protection and Big Data management, has announced the new DXi6800 Series deduplication appliance, combining industry- leading performance, scalability and efficiency with ‘pay-as-you- grow’ extensibility.


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Supercomputers have been used to decipher Earth’s last major period of rising temperatures


T


hree years of work – and 14 million processor hours – using the Jaguar supercomputer have unlocked


the secrets of Earth’s last major deglaciation.


Our planet has experienced warming and cooling throughout its history. About 22,000 years ago Earth’s ice sheets declined – slowly at first, but then more rapidly. Given concerns over today’s shrinking glaciers and ice caps, knowledge of previous deglaciations are of great importance. While researchers agree that a rapid about 17,000 years


release of CO2


ago led to a rise in temperatures, it was not known until recently what set the ball rolling. Now researchers from the University of Wisconsin-Madison, Harvard University, Oregon State University, and the National Center for Atmospheric Research (NCAR) have discovered the trigger for the beginning of the last great deglaciation. The team ran continuous simulations on Oak Ridge National Laboratory’s (ORNL) Jaguar supercomputer over three years to create the first physics- based test of hemispheric deglaciation. They discovered an increase in insolation (solar radiation reaching Earth) caused by changes in Earth’s orbit, and ocean circulation. The simulations, by Feng He and Zhengyu Liu of UW-Madison and Bette Otto-Bliesner of NCAR, build on simulations at ORNL and featured in Science in 2009 and Nature in 2012. The research is part of a larger


14 SCIENTIFIC COMPUTING WORLD


THE SIMULATION REPRODUCES THE SOUTHERN HEMISPHERE PROXY RECORDS BEAUTIFULLY


a ‘freshwater lid’ over the North Atlantic and block the entire conveyor belt. The simulations showed a weakening of the AMOC and a decrease in ocean heat transport, keeping heat in the southern hemisphere and cooling the northern hemisphere – leading to a phenomenon known to climatologists as ‘the bipolar seesaw’.


release of CO2


This, in turn, led to an enormous from primarily beneath


the ocean, which then greatly accelerated the warming of the globe. ‘When the CO2


came out, everything


changed,’ explained He. Essentially, said He, the timeline for the Earth’s last deglaciation is as follows: from 22,000 to 19,000 years ago, northern hemisphere insolation


The OLCF has given the project nearly four continuous years of access, allowing the team to run climate simulations over 22,000 years and produce nearly 300 terabytes of data. ‘We have the resources to stage all data online for analysis,’ said the OLCF’s Valentine Anantharaj, who worked with the team to make sure they got the most from their time on Jaguar. Anantharaj now works with users on the 10-fold more powerful Titan system, and says the OLCF represents a valuable end-to-end resource capability: ‘Our facility supports a scientific workflow that enables our users to run their simulations, do their analyses and visualise and archive the results.’ Report by Tim Gillett


@scwmagazine l www.scientific-computing.com


initiative that has obtained a mean global temperature for the past 21,000 years, enabling comparisons of carbon dioxide levels and temperatures across the world. Jaguar, managed by the Oak Ridge Leadership Computing Facility (OLCF), has since transitioned to Titan, currently recognised as the fastest computer in the world.


Data shows that about 19,000 years


ago, northern hemisphere glaciers began to melt, and sea levels rose. Glaciers released so much fresh water into the ocean that it slowed a system of currents known as the Atlantic meridional overturning circulation (AMOC). This ocean conveyor belt flows northward across the equator, taking southern hemisphere heat and exporting it to the northern hemisphere. The AMOC then sinks in the North Atlantic and returns south. A large pulse of glacial meltwater, however, can place


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Deglaciation secrets unfrozen


triggered its gradual warming as a result of the large increase in high- latitude spring/summer insolation and strong sensitivity of the land-dominated northern high latitudes to insolation forcing; from 19,000 to 17,000 years ago the AMOC phenomenon primarily accounts for early southern hemisphere warming and deglaciation; and the rise in CO2


starting around 17,000 years


ago brought about the final stages. The simulations have consumed


more than 14 million processor hours on Jaguar. The team’s weapon of choice was the Community Climate System Model (CCSM), a model that includes coupled atmospheric, land, ocean and sea ice models.


‘The simulation reproduces the southern hemisphere proxy records beautifully. A good model is the result of many people’s efforts,’ said He.


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