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Table 1.

Back mapping polarity measure for the spherical source surface at 2.5 R.

Spacecraft Solar wind Period 1 (declining) Period 2 (minimum) Period 3 (maximum)
type CR2041−CR2055
CR2066−CR2075
CR2133−CR2142
n pm, s/pm, e σs/σe n pm, s/pm, e σs/σe n pm, s/pm, e σs/σe
(%) (%) (%) (%) (%) (%)
ACE Ejecta 969 79/79 2.9/3.0 485 73/75 2.4/2.6 1644 72/71 1.7/1.7
Coronal hole 8464 94/93 0.2/0.3 11 097 94/94 0.2/0.2 5364 89/85 1.2/1.8
Sector reversal 10 646 60/60 1.2/1.3 7570 65/69 1.9/1.6 7822 59/57 0.8/0.9
Streamer belt 11 494 79/77 0.7/0.9 13 284 81/82 0.5/0.7 14 076 76/70 1.4/1.9
Overall 31 573 76/75 0.7/0.8 32 436 82/83 0.5/0.5 28 906 74/69 1.0/1.2
STEREO-A Ejecta 15 048 87/86 1.6/1.9 40 060 74/72 1.1/1.4
Coronal hole 123 548 89/90 0.5/0.3 61 216 90/88 0.4/0.6
Sector reversal 66 893 61/68 2.0/1.2 46 468 51/53 1.9/1.8
Streamer belt 163 059 83/84 0.6/0.6 155 228 75/72 1.1/1.3
Overall 368 548 81/83 0.6/0.4 302 972 74/72 0.7/0.9
STEREO-B Ejecta 8421 81/85 4.0/2.0 10 325 76/79 1.5/1.3
Coronal hole 91 748 93/93 0.4/0.5 8003 87/71 2.8/8.1
Sector reversal 58 988 67/72 1.2/1.2 7956 64/64 1.5/2.3
Streamer belt 108 680 83/82 0.9/1.2 30 247 74/73 1.3/1.9
Overall 267 837 83/84 0.7/0.7 56 531 75/73 1.2/1.6

Notes. The first column lists the spacecraft, the second column lists the solar wind types, and Cols. 3−5 show the data for three different periods. Also shown are the sample count (n) and the correctly predicted magnetic field polarity fractions (pm, s/e) and standard deviations (σs/e) of the evaluation procedure for the standard rss = 2.5 R spherical PFSS model (subscript s) and the elliptic model with parameters rss = 2.5 R and eo = 1.667 (subscript e). Data samples were partitioned according to the Xu & Borovsky (2015) scheme into four classes of solar wind types for three periods (columns) and three spacecraft (rows). Analyzing streamer belt wind on the ACE during solar activity minimum shows that there were n = 13 284 data samples available, 80.8% (= pm, s) of which mapped to correctly predicted magnetic field polarities on the source surface with a standard deviation of σs = 0.5% in the spherical model.

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