Open AccessAn improved method of inferring interplanetary sector structure, 1905‐present
Author(s) -
Vennerstroem S.,
Zieger B.,
FriisChristensen E.
Publication year - 2001
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2000ja000103
Subject(s) - interplanetary spaceflight , polarity (international relations) , earth's magnetic field , interplanetary magnetic field , asymmetry , physics , geophysics , computational physics , magnetic field , solar wind , chemistry , biochemistry , quantum mechanics , cell
A new method of estimating interplanetary sector polarity from geomagnetic activity is presented. The method is based on a linear multiregression between the B y component of the interplanetary magnetic field and hourly values of the magnetic perturbation (Δ X , Δ Y , Δ Z ) at selected magnetic observatories. By simultaneous use of all three components, and by using all hours of local time, the method yields an improved accuracy compared to previous subjective assessments of the sector polarity. Using this method, it is possible to derive the interplanetary sector structure at least back to 1926, with an accuracy which is sufficient to follow the development of large‐scale unipolar structures in the interplanetary medium. Furthermore, we present results indicating that it may be possible to derive sector polarity even further back in time to 1905, but with less accuracy. This is accomplished by including the two subauroral stations Sitka and Sodankylä, which have not previously been used for polarity determination. A major problem with this early polarity determination is a strong asymmetry favoring toward sectors.