Table 1.
Summary of the various exponents ax describing the radial scaling of the mean solar wind parameters ⟨X⟩sw in the inner heliosphere based on theoretical arguments, Helios observations, and EUHFORIA modelling results.
| Parameter | Theory | Observations |
Simulations | ||
|---|---|---|---|---|---|
| All | Fast | Slow | Slow | ||
| av | 0 | [0.036, 0.083] | – | – | 0.04 ± 0.01 (0.02 ± 0.01) |
| anp | −2 | [ − 2.10, −2.01] | [ − 2.03, −1.89] | −1.9 | −2.07 ± 0.05 (−2.14 ± 0.05) |
| aB | [ − 2, 0] | [ − 1.92, −1.47] | [ − 1.91, −1.53] | [ − 1.88, −1.40] | −1.55 ± 0.09 (−1.65 ± 0.05) |
| aTp | −4/3 | −0.79 | [ − 0.9, −0.69] | [ − 1.21, −0.58] | −0.96 ± 0.06 (−1.03 ± 0.02) |
| aPp, th | −10/3 | – | [ − 3.0, −2.8] | – | −2.77 ± 0.16 (−3.16 ± 0.07) |
| aPmag | [ − 4, 0] | – | [ − 3.3, −3.1] | – | −2.79 ± 0.17 (−3.31 ± 0.11) |
| aβp | [ − 10/3, 2/3] | – | [0.3, 0.5] | – | 0.52 ± 0.67 (0.15 ± 0.10) |
Notes. The […, …] notation is used to indicate the lower and upper boundaries of each value range, as derived from theoretical and observational arguments. In the right-most column, we indicate the uncertainties (±) on the simulated values based on 95% confidence intervals. In this column, we also indicate in brackets the values based on the median in order to provide a comparison with the mean-based parameters used in the analysis.
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