Solar Sector Boundaries Data (All ftp)

Solar Sector Boundary Crossings -- Solar magnetic field lines are convected away from the sun by the expanding solar wind, along the Archimedes spiral induced by solar rotation (Parker, 1958). The interplanetary magnetic field (IMF) is highly ordered and organized, with interplanetary sectors or extended regions of space where the magnetic field line polarities are directed either away from the sun or towards the sun (Wilcox and Ness, 1965). This polarity can be inferred with a high degree of reliability from polar cap magnetometer data from Thule and Vostok stations during the summer months (Svalgaard, 1974). For a field reversal to be classified as a sector boundary, Svalgaard generally required that the polarity be the same for at least 4 days before the reversal, and that it remain reversed for at least 4 days following the reversal. Svalgaard thereby distinguished between large-scale sector structure and fine-scale filaments and reversals. Almost all large-scale features are recurrent, while almost all small-scale features are not. Occasionally a 4-day-wide sector may recur as one only 3 days wide, and then later again, become 4 or more days wide. In such cases the 4-day criterion described above was relaxed in order not to miss what obviously was a real sector boundary rather than just a transient reversal. A list of such well-defined sector boundary passings can be seen in Bartels rotation plots of the sector polarities.

In the following tables, the time of day of the boundary passage is always given as nominally 0000 UT, because of the 1-day time resolution in the list of polarities. Thus, the most probable time of the boundary passage is within 12 hours of the time given. The data include an indication of the polarity change across the boundary: (+,-) or (-,+), where + designates AWAY from the sun and - designates TOWARD the sun. The Bartels rotation number and (within that same rotation) the first day of the new sector are given.

• Dates of Solar Sector Boundary Crossings 1947-1978
• Daily Inferred Interplanetary Magnetic Field Polarity Data 1947-1975 where c = Toward polarity; b = Mixed polarity; a = Away polarity -- listing by month.
• Daily Inferred Interplanetary Magnetic Field Polarity Data 1947-1975 where c = Toward polarity; b = Mixed polarity; a = Away polarity in x-y plot file

• A = Interplanetary Magnetic Field directed Away from the Sun; T = Towards; AT = changeover from A to T; TA = changeover from T to A; - = No data available.
  • 1979 Table
  • 1980 Table
  • 1981 Table
  • Plottable file in x-y format for 1974-1981

• A = Interplanetary Magnetic Field directed Away from the Sun; T = Towards; AT = changeover from A to T; TA = changeover from T to A; - = No data available.
  • 1971 1972 1973 1974 1975 1976 1977 1978 1979
  • 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989
  • 1990 1991 1992 1993 1994
    • IMF Polarity from Ground-based Measurements from 1957 - 1994 in Bartels Rotation plot -- Data provided by the Polar Geophysical Research Laboratory of IZMIRAN, Russia. + = away the sun; - = toward; X = not available
    • Plottable file in x-y format for 1971-1994
    
    

• A plot is available of the IMF azimuthal angles 1963-present computed from daily averages of hourly GSE X and Y IMF components as contained in the OMNI data set. In the plot blue denotes angles in the range 90-180 deg., typical away or positive polarity. Red denotes angles in the range 270-360 deg., typical toward or negative polarity. Yellow denotes angles in either of the other two azimuthal quadrants. White means no data. Data for two successive solar rotations (54 days) are shown on each line. The data for one solar rotation are shown on the right side of one 54-day line and on the left side of the next line.
• A table of daily IMF azimuthal angles 1963-present is also available.