Geomagnetic Activity Forecasting: the State of the Art

Short-term (days to weeks) geomagnetic forecasts are valuable for a variety of public and private sector endeavors. However, forecast skill, as measured by the success of predicting geomagnetic indices, is disappointing, especially for disturbed conditions. Possible reasons for this lack of proficiency include an incomplete understanding of the solar origins of interplanetary disturbances, insufficient observations of solar phenomena and interplanetary disturbances, and an underestimation of magnetosphericionospheric control of observed geomagnetic activity. Until more progress can be made on each of these problems, desirable forecasting precision is likely to remain elusive. The best opportunity for improved service to those agencies requiring advance notice of geomagnetic disturbances is "nowcasting" using realtime, near-Earth observations of the approaching solar wind.