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S.J. Robbins (CWRU), C.J. Henney, J.W. Harvey (NSO)
An empirical model for forecasting solar wind speed related geomagnetic events is presented. The model is based on the location and size of solar coronal holes determined with Kitt Peak Vacuum Telescope \ion{He}{1} 1083.0 nm spectroheliograms and photospheric magnetograms. This method differs from the Wang-Sheeley model that is based on photospheric magnetograms to estimate the open field line configuration. Solar wind and coronal hole data for the period between May 1992 and September 2003 are investigated.
The new model is found to be accurate to within 4.5-5.7% (the range depends upon the number of days ahead forecast) of observed solar wind measurements for the best one-month periods within the time frame studied; the overall 11-year correlation is as high as 0.382. Using coronal hole maps, the model can predict the solar wind velocity up to 8.5 days in advance with an average fractional deviation as low as 9.4-10.0% for a given one-month period. This is further in advance forecasting and up to a factor of 2 improvement over the Wang-Sheeley model. Its main features are a strong southern hemisphere bias, sunspot cycle dependence, and that a complete forecast of up to 9 days can be made from a single solar image, as opposed to a full synoptic map required by the Wang-Sheeley model.
This work is carried out through the National Solar Observatory Research Experiences for Undergraduate (REU) site program, which is co-funded by the Department of Defense in partnership with the National Science Foundation REU Program. This research was supported in part by the Office of Naval Research Grant N00014-91-J-1040. The National Solar Observatory is operated by AURA, Inc. under a cooperative agreement with the National Science Foundation.
The author(s) of this abstract have provided an email address for comments about the abstract: sjr16@cwru.edu
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.