Synthetic four-solar-cycle solar wind at 1 AU generated from the OMNI data set

• Published in: Journal of geophysical research. Space physics Vol. 118; no. 2; pp. 615 - 627
• Main Authors: Thatcher, L.J., Müller, H.-R.
• Format: Journal Article
• Language: English
• Published: Washington Blackwell Publishing Ltd 01-02-2013
• Subjects: Magnetic fields; Solar cycle; solar wind; Wind
• ISSN: 2169-9380; 2169-9402
• DOI: 10.1002/jgra.50150

Numerical modeling provides key insights into the physics of the outer heliosphere. The solar wind data utilized by these models impact their accuracy and should be as close as possible to the actual solar wind. Because of the time scales involved, such a data set should also span several solar cycles. Yet the bulk of solar wind measurements in such a time frame was obtained near Earth. A method to infer the solar wind at points not directly observed is developed such that a 1 AU ring in the ecliptic plane is filled with four solar cycles of solar wind data. Hourly OMNI data are used as the seed data. The OMNI data are separated into four separate categories, and those categories are first extrapolated, generating a continuous 2‐D category map of the solar wind for the full four solar cycles covered by OMNI. The category map is used to determine solar wind characteristics. The solar wind values are determined by local running averages coupled with a random walk technique. The averages provide baseline values and the random walk adds short‐duration deviations from this baseline. The statistics from the extrapolated data are compared to the statistics of the original OMNI data set. Category durations, relative coverage, variable distributions, and correlations are similar to those of the OMNI data, although with some discrepancies.
Key Points
Four solar cycle solar wind data for ecliptic
Can model solar wind as modified random walk
Statistics from OMNI and generated data very similar