Wednesday, December 18, 2013

Space Weather model selected to improve US warning system

A University of Michigan space weather model beat out four other contenders for a spot in the national Space Weather Prediction Center's forecasting toolbox.

It is the first time that computer models based on a firm understanding of physics have overtaken simpler, statistics-based models to predict magnetic disturbances due to space weather.

The new model can also give information about where the effects of a geomagnetic storm will be weaker or stronger around Earth.

Space weather forecasts are important for protecting satellites, predicting when GPS signals become unreliable, and in the worst case, preventing far-reaching and long-term electrical power outages.

Most of the time, Earth's magnetic field unflinchingly deflects most of the charged particles shed by the sun, known collectively as the solar wind.

Yet every now and again, the sun ejects a chunk of material—still charged particles but a lot more of them.

"You can have eruptions like coronal mass ejections or solar flares, and these propagate all the way from the sun to the earth," said Gábor Tóth, a research scientist in atmospheric, oceanic and space sciences and one of the model's main developers.

In a gale-force solar wind brought on by these eruptions, Earth's magnetic field shakes.

The main fear is that this shaking could knock out the big transformers in the electrical grid.

Simulation results show the solar wind in gray with Earth's magnetic field in shades of blue and yellow, corresponding to different pressures. 

The white ball is 2.5 times the size of Earth. 

Credit: Visualization created by Darren De Zeeuw, Dept. of AOSS

"These power grids always operate on the edge, and if you put an extra load on, they can fail," Tóth said.

As Earth's magnetic field moved, it would create its own currents in the high-voltage cables that carry electricity across hundreds of miles.

At substations, where transformers convert the electricity to lower voltages for delivery into cities and towns, that extra current would likely push transformers over the edge.

Since crisscrossing the Earth with high-voltage cables and sending satellites into orbit, humans haven't experienced space weather that could cause worldwide disruption.

The last event of that magnitude was in September 1859. Only the telegraph system was around to preview how Earth's roiling magnetic field can fry long-distance electrical systems.

Because large transformers take between five months and five years to build, a modern version of that storm could mean prolonged, extensive blackouts.

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