Predicting auroras

The Sun emanates a continous flow of charged particles (electrons and protons) to its surroundings. This flow is called solar wind. The bursts in the solar wind generate auroras and other space weather phenomena. The amount of solar wind bursts is known to vary with 11 year periodicity and to have a close correlation with the sunspot number. Individual bursts can be associated with large phenomena (coronal holes, flares and mass ejections) taking place in the solar atmosphere (corona). Thus monitoring the solar surface has a crucial role in predicting auroras: when e.g. a coronal mass ejection has been regonized from solar surface observations its arrival to near-Earth space can be anticipated to happen within 1-2 days. Solar wind observations from satellites residing in the space near the Sun-Earth line further confirm the predictions.

Observing the solar phenomena alone is not enough to make realiable auroral predictions. It is namely the solar wind-magnetosphere interaction processes and certain magnetospheric phenomena which finally dictate whether the solar wind burst is effective in generating auroras or not. These phenomena are known in general level and they can be modelled with computer simulations, but some crucial details still lack of comprehensive scientific understanding. Progress in this research is naturally of primary importance for reliable predictions, but the innovations in the area of artifical intelligence have been useful also in the space weather research. The long time series of ground based and satellite observations collected for research purposes can be used in teaching neural networks which then can be used in different prediction codes.

Photo: J. Jussila Photo: M. Oksanen Photo: J. Kinnunen

An image by SOHO satellite showing a coronal mass ejection emanating from the Sun surface. More images by SOHO.

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Links for auroral tourists:

Chasing the northern lights
Spotting auroras in Lapland