ESA: SOHO Predicts Solar Storms

A new method, based on data from the COSTEP instrument onboard SOHO, permits for the first time up to an hour of warning prior to the arrival of the most dangerous particles of a solar storm at Earth.

Solar storms consist of electrons, protons and heavy ions, the last of which pose the gravest danger to space-borne electronics and to humans outside the Earth's protective magnetic field (such as on the Moon or en route to Mars). Electrons arrive first, signaling the later arrival of the ions.

So far, however, there had been no adequate method to predict when these ions arrive. Sufficient advance warning allows for spacecraft to be put in a protective "safe mode" and humans to be instructed to seek shelter from the storm.

Arik Posner, a physicist in NASA's Science Mission Directorate, looked at hundreds of radiation storms recorded by COSTEP (Comprehensive Suprathermal and Energetic Particle Analyzer) between 1996 and 2002, and was able to construct an empirical, predictive matrix that can be used to forecast the ions' arrival time from the electron data.


Posner's ion storm forecasting matrix. Click here to view a more complete version of the matrix with extended caption.

After testing the results, the matrix was used on COSTEP data gathered in 2003, a year that had not yet been analyzed and formed no part of the matrix itself.

The matrix was applied to the electron data and as a result, it successfully predicted all four major ion storms of 2003 with advance warnings ranging from 7 to 74 minutes.

The method did, however, also create three false alarms from the 2003 dataset. Improvements will come as Posner works his way through even more of COSTEP's dataset.

Posner's forecasts for the intense "Halloween storms" of 2003. Black denotes the predicted ion flux; red is what was actually observed.

The COSTEP instrument was launched with SOHO in 1995.

It has been operating for more than a whole solar cycle, which lasts on average 11.1 years, and is still going strong.