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[72.03] Determining Shock velocities that are needed for model inputs at the Sun from from ground-based radio data and space-based coronagraph data.

Z. Smith, M. Dryer (NOAA/SEC), C. D. Fry (Exploration Physic International, Inc.)

The speed of a shock that precedes ejecta from a solar energetic eruption is a key parameter used for input by many numerical modeling codes that predict the arrival of interplanetary shocks at Earth. These shocks are likely to be followed by significant geomagnetic activity. Near- real-time forecasts of these shock arrival times at the L1 libration point have been made for several years with several models and distributed by e-mail to interested subscribers (“fearless forecasts”). These models use, for input speed near the Sun, the speeds obtained from observations of metric type II bursts that are signatures of a shock propagating out through the solar corona. More recently, speeds of the halo/partial halo CMEs were also considered in these models as another measure of shock speeds close to the Sun. During the Oct.-Nov. 2003, Halloween, interval, the fearless forecasts were issued in a number of cases with alternate inputs. This provided a basis on which to compare the success of the predictions (in terms of how close each prediction of the shock arrival time was to the observed time). This data set is analyzed to give guidelines to the selection of the speed for use as input to shock propagation models, and to show the usefulness of both the metric radio burst data and coronagraph data for this purpose.

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Bulletin of the American Astronomical Society, 36 #2
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