Prediction of Magnetic Storms by Nonlinear

The strong correlation between magnetic storms and southward interplanetary magnetic eld (IMF) is well known from linear prediction lter studies using the Dst and IMF data. However, the linear lters change signiicantly from one storm to another and thus are limited in their predicting ability. Previous studies have indicated nonlinearity in the magneto-spheric response as the ring current decay rate varies with the Dst value during storms. We present in this letter nonlinear models for the evolution of the Dst based on the OMNI database for 1964-1990. When solar wind data are available in advance, the evolution of storms can be predicted from the Dst and IMF data. Solar wind data, however, are not available most of the time or are available typically an hour or less in advance. Therefore, we have developed non-linear predictive models based on the Dst data alone. In the absence of solar wind data, these models cannot predict the storm onset, but can predict the storm evolution, and may identify intense storms from moderate ones. The input-output model based on IMF and Dst data, the autonomous model based on Dst alone, and a combination of the two can be used as forecasting tools for space weather.