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Table 4 Estimated Dstmin based on formulae obtained from Wu and Lepping (2016) with \( B_{{z_{ \hbox{min} } }} \) = −23 nT

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

Range of MC’s averaged speeda Estimating Dst formula using \( B_{{z_{ \hbox{min} } }} \) in MCb Pred. Dst cmin Error (%)d Estimating Dst formula using \( B_{{z_{ \hbox{min} } }} \) in MC or sheathb Pred. Dst cmin Error (%)d
1. V < 400a Dstmin = 12.12 + 6.55\( B_{{z_{ \hbox{min} } }} \) −138.5 39.3 11. Dstmin = 14.19 + 6.52\( B_{{z_{ \hbox{min} } }} \) −135.8 40.4
2. 400 < V < 500 Dstmin = −21.08 + 4.82\( B_{{z_{ \hbox{min} } }} \) −131.9 42.1 12. Dstmin = −16.14 + 4.50\( B_{{z_{ \hbox{min} } }} \) −119.6 47.5
3. 500 < V < 600 Dst min  = −9.31 + 9.08 \( B_{{z_{ \hbox{min} } }} \) −218.2 e 4.3 13. Dstmin = 28.94 + 8.23\( B_{{z_{ \hbox{min} } }} \) −160.4 29.6
4. 600 < V < 750 Dst min  = −70.76 + 6.55 \( B_{{z_{ \hbox{min} } }} \) −221.4 2.9 14. Dstmin = 36.18 + 8.65\( B_{{z_{ \hbox{min} } }} \) −162.8 28.6
5. V > 750 Dstmin = −147.07 + 2.84\( B_{{z_{ \hbox{min} } }} \) −212.4 6.8 15. Dstmin = −32.14 + 4.54\( B_{{z_{ \hbox{min} } }} \) −136.6 40.1
94 MCshock       
 6. V < 400 Dstmin = 12.28 + 6.82\( B_{{z_{ \hbox{min} } }} \) −144.5 36.6 16. Dstmin = −10.83 + 5.42\( B_{{z_{ \hbox{min} } }} \) −114.8 49.6
 7. 400 < V < 500 Dstmin = −43.37 +3.37\( B_{{z_{ \hbox{min} } }} \) −120.9 47.0 17. Dstmin = −36.69 + 3.21\( B_{{z_{ \hbox{min} } }} \) −111.7 51.0
 8. 500 < V < 600 Dstmin = −54.55 + 4.72\( B_{{z_{ \hbox{min} } }} \) −163.1 28.5 18. Dstmin = −13.01 + 5.14\( B_{{z_{ \hbox{min} } }} \) −132.8 41.8
 9. 600 < V < 750 Dstmin = −66.72 + 7.53\( B_{{z_{ \hbox{min} } }} \) −239.9 5.2 19. Dstmin = 75.96 + 10.43\( B_{{z_{ \hbox{min} } }} \) −191.2 16.1
 10. 750 < V Dstmin = −147.07 + 2.84\( B_{{z_{ \hbox{min} } }} \) −212.4 6.8 20. Dstmin = −32.14 + 4.54\( B_{{z_{ \hbox{min} } }} \) −141.9 37.9
  1. aRange of averaged speed inside of the MC
  2. bLinear-fitted function for Dstmin obtained from Wu and Lepping (2016)
  3. cPredicted Dstmin by using Dstmin formula listed in the left
  4. dError = |(Dstobs–Dstpred.)/Dstobs.|
  5. eDstprediction = −218.2 nT (\( B_{{z_{ \hbox{min} } }} \) = −23 nT) using Dstmin formula 3) for 500 < V < 600 km/s
  6. Italics: the “best prediction” (with the lowest error) for Dst min