The first super geomagnetic storm of solar cycle 24: “The St. Patrick’s day event (17 March 2015)”

Earth, Planets and Space

Table 1 MC fit-parameters for the MC of 17 March 2015 (starting day)

ΔT, duration of the MC encounter (i.e., ΔT = end time – start time of MC passage); V _MC, average solar wind speed (in km s⁻¹) within the MC; 2R _o, estimated diameter (in AU), where R _O is the model-estimated radius; B _O, estimated axial magnetic field magnitude (in nT); H, Handedness (+1 for right-handed or −1 for left-handed); ϕ _A, θ _A, longitude and latitude, respectively, of the MC axis (GSE coordinates); t _o, estimated center time of the MC; χ _R, square root of the reduced Chi-squared of the MC fit; asf(%), asymmetry factor (in %), which depends on t _o and ΔT; CA (%), estimated relative closest approach distance, i.e., y _o/R _o (in %) where y _o is closest approach; Φ _o, estimated axial magnetic flux (in 10²⁰ Mx); J _O, estimated total axial current density (in μA km⁻²); Δt, length of the averages used in the analysis; these are usually 15, 30 min, or 1 h; β _CA, cone angle, the angle between the MC axis and the X-axis (in GSE coordinates); “Check,” a check of the estimated radius by using duration, speed, CA, cone angle, and R _o; I _T, estimated total axial current (in 10⁸ A); N, number of points used in the MC-fitting interval; Q _o, estimated quality of the model fitting (where Q _o = 1, 2, or 3, for excellent, good, or poor, respectively)