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B.V. Jackson, P.P. Hick, A. Buffington (CASS/UCSD)
Solar disturbances produce major effects in the corona, its extension into the interplanetary medium, and ultimately, the Earth's environment. The ability to determine the three dimensional extent of these disturbances and to forecast their arrival at Earth is of primary scientific and practical interest. We have developed a tomographic technique for use in mapping these disturbances as they move away from the Sun. Our technique uses a solar wind density and velocity model and available remote sensing data and iterates to a least squares fit solution of these data. This technique provides more contrast between high and low speed winds and more or less dense solar wind structures than has been possible with previous techniques.
Existing observations include those from the HELIOS photometers (Thomson scattering data) and velocity and scintillation-level measurements (from interplanetary scintillation or IPS data). The latter observations are currently available on a daily basis from the Solar Terrestrial Environment Laboratory situated near Nagoya, Japan. We are developing a way to provide a tomographic reconstruction from IPS data in real time for use in heliospheric space weather forecasting, and we show our most recent results on this. We are also in the process of developing this technique to provide the three dimensional extent of heliospheric features which vary in shape over short periods of time (i.e., CMEs). The result using this extension of the technique is commensurate with the quantity, quality and perspective views present from the remote sensing data, and with present data is used to explore the extent to which solar corotating structures are time-variable. As other remote sensing data become available with high angular and temporal resolution from spacecraft instruments such as the Solar Mass Ejection Imager (SMEI), now being developed and constructed for the Air Force, or as proposed for the NASA STEREO or Solar Probe Missions, the technique should provide far better heliospheric three dimensional and temporal resolution (by several orders of magnitude) than now available.
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s follows:
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