27 October, 2009

Scientists from the British Antarctic Survey and the Space Weather Prediction Center in Boulder, Colorado, have shown that high energy charged particles that are usually trapped in the Earth’s magnetic field are released into the atmosphere at different locations during geomagnetic storms. The results will help to refine models of atmospheric chemistry and climate.

A paper published this month in the Geophysical Research Letters describes how 9 years of data from low-altitude satellites was used to analyse the different phases of geomagnetic storms, which are large scale disruptions in the Earth’s magnetic field that may last for days. The analysis shows that during a geomagnetic storm, lower energy electrons are released into the Earth’s atmosphere almost immediately and at any longitude, but higher energy electrons are only released a few days later. The release of the higher energy electrons is also limited to a region that extends from the South Atlantic over the Antarctic peninsula towards the South Pole.

As higher energy electrons penetrate deeper into the atmosphere and deplete ozone, this means that the effects of the higher energy electrons on atmospheric chemistry will be largest just poleward of the South Atlantic anomaly, and will occur a few days after the peak of magnetic storms.

Chemistry climate models must take the timing and location of precipitation at different energies into account when modelling the atmospheric response to geomagnetic storms and solar variability.

Energetic electron precipitation from the outer radiation belt during geomagnetic storms by Richard B. Horne, Mai Mai Lam, and Janet C. Green is published this month in Geophysical Research Letters and has been selected as an AGU journal highlight.

Related links

Geophysical Research Letters Editors’ Highlight

Space Weather Prediction Center