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The Sun through clouds

Solar flares during an active part of the Solar Cycle.
The Sun during an active time, with lots of Solar flares. Image courtesy Yohkoh Solar Observatory.

We are about two and a half years into the Sun's latest solar cycle, Solar Cycle 24, which will reach its peak in 2013, according to NASA scientists. This peak is expected to be small, however, with the fewest sunspots in over 100 years.

However, even a quiet Sun can produce severe space weather, such as the Carrington Event of 1859, which electrified telegraph transmission cables around the world, created fires in telegraph offices, and produced Northern Lights so bright that people could read newspapers by their red and green glow, according to a Science@NASA article.

If a super-solar storm happened today it could severely disrupt our high-tech communications and cost trillions in damages. But a team of scientists in the UK and the US use cloud computing to simulate how the Sun generates these flares to better understand these occurrences.

Studying Alvfen waves

Mahboubeh Asgari-Targhi, a scientist from University College London,works on the Elastic Virtual Infrastructure for Research Applications (ELVIRA) project. She looks at heating of the Sun's upper atmosphere and therefore how solar flares work.

Asgari-Targhi , and her colleague A. Van Ballegoojen, from the Center for Astrophysics at Harvard University in Boston, study the structure, dynamics and thermal processes of a layer called the chromosphere. This is a transparent top-layer, with jet-like features just above the surface of the photosphere, which is where the Sun's light originates.

Specifically, what they study is called 'Alfven wave turbulance'. "Alfven waves are magnetohydrodynamic waves in plasma that propagate along the Sun's magnetic field lines. We investigate the role Alfven waves play in heating the coronal plasma in the solar active regions. This will hopefully result in understanding the coronal heating and solar flares better," Asgari-Targhi said.

Working with layers

ELVIRA enables Asgari-Targhi to use a hybrid-cloud computing service, made up of St Andrews Cloud Computing (StACC), the UK's first university research cloud and Amazon's commercial EC2 cloud. She is able to make use of computation for simulations and data resources provided by the StACC cloud, as well as resources from Amazon's EC2 infrastructure.

XRT (X-Ray Telescope) image of the Sun's active region taken on Thursday 5th May 2010 by the Hinode satellite telescope. Asgari-Targhi and her colleagues used these images for analysis.
XRT (X-Ray Telescope) image of the Sun's active region taken on Thursday 5th May 2010 by the Hinode satellite telescope. Asgari-Targhi and her colleagues used these images for analysis.

For Asgari-Targhi, this hybrid cloud set-up is invisible, allowing her to focus on her research while ELVIRA's software ensures that resources scale automatically - switching from StACC to EC2 and back - depending on her processing requirements.

"ELVIRA is aimed at researchers who find it difficult to use e-science infrastructures such as grids. Those with large-scale problems but a lack of access to computational and storage resources can now easily use clouds," said Alex Voss, a lecturer in software engineering working on ELVIRA.

Making jobs easier

Even though grid computing is normally used for large-scale parallel processing, Asgari-Targhi's large requirements mean that she needs an infrastructure that can provide for long-running jobs, with large memory requirements and support from interactive analysis tools.

"Job running times can be up to five days for the most complex simulations and the need for collaborative interactive tools and specific software licenses make the code difficult to run on grids," said Voss.

Astrophysics simulations can run for almost one hour and require significant amounts of memory and storage capacity as they generate output files of up to 80GB. "It is clear that this figure will be rising as Asgari-Targhi is planning to push the boundaries of her research further," said Voss.

Resource centers become virtualized

"A hybrid cloud provides a user with a set of generic tools, such as a job submission interface. This interaction means a user does less to get more," said Voss. Traditionally, within a grid interface, a user has to meet the computing requirements of the environment they're sending their job too. This means fiddling with a lot of code to configure the correct operating system, software or data libraries within their job.

With ELVIRA's cloud service, virtualization configures the computing environments for users, providing them with a selection of configured templates, which provide resources for batch job submission, interactive or collaborative use.

European Grid Infrastructure (EGI) is also considering cloud resources like this for peak download periods. "We are expecting more and more resource centers to become virtualized. What we need to do is expose this virtualization so that it is accessible to end-users in virtual research communities so that they can deploy their own environments," said Steven Newhouse, EGI Director.

Shortest length of study: 84 Mega meters

"Users will be able to create jobs with fewer parameters. They will stop worrying about being a UNIX or Windows system administrator and focus on their research," said Voss.

This cloud service enables Asgari-Targhi to work in a virtual laboratory and create complex simulations of the Sun's corona up close and in detail, while staying cool. She studies coronal loops within 'small' areas of the Sun's surface. "The important factor in our numerical simulation is the length of these loops and it varies. The shortest coronal magnetic field line that we are simulating is 84 Mega meters [84,000 km or 52,195 miles]," she said.

Although solar flares are common and naturally occurring, the large solar flare last month raised concerns about Earth's current vulnerability. A better understanding of the Sun's coronal ejections will lead to more accurate detectors and earlier warnings of super-solar flares.

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