Finnish Meteorological Institute maintains an automatic auroral alert system for South Finland. It is based on magnetic recordings at Nurmijärvi station and send an e-mail whenever the derivative of the magnetic field exceeds a certain threshold value. When the magnetic field on the ground changes fast we expect a stormy space weather and probably some auroral activity. The level of magnetic disturbances is updated once an hour. Thus, a longer event may cause hourly arriving alerts. Observing the aurora requires dark sky and clear skies in addition. To see auroras in North Finland is about ten times more possible than in South Finland.
An example of the alert e-mail:
NUR XYDERIV=371 (2001-09-25-23UT)
where XYDERIV=371 is the maximum temporal change of magnetic X and Y components (in nanoTeslas). If this number is larger than 30 the level of activity is high enough so that aurora may be seen also in the Southern Finland. The numbers in the parenthesis mark the year, month, say and UT hour of the observation.
To subscribe for the auroral alert send a message to email@example.com or to unsubscribe e-mail firstname.lastname@example.org
From early May until mid-August the nights are not dark enough for auroral observations and during that time the alert system is not in operation.
For more details: kirsti.kauristie "at" fmi.fi