Extended geomagnetic storm forecast ahead of available solar wind measurements

Abstract

We develop a technique to predict geomagnetic storm magnitudes (peak Dst values) several hours in advance using the first indications of extreme solar wind conditions, as well as an assumption of constant driving function V Bs. For larger storms with clear V Bs jump we predict lower and upper limits of expected peak Dst. For smaller storms and storms with gradually increasing V Bs we predict Dst several hours ahead. The data from 1995-2010 were used to design the technique. The actual advance time of reliable forecasts (before the peak value is reached) is on average 5-6 hours, illustrating the realistic horizon of such "constant input" assumption. Larger storms are developing faster and thus are better predicted. False warnings (predictions more than 25% larger than the actual peak) occur in about 10% of events. The algorithm is implemented in real-time in Space Research Institute, Moscow (www.spaceweather.ru). © 2012. American Geophysical Union. All Rights Reserved.