Solar wind parameters and geomagnetic indices for severe (SYM-H < -100nT) geomagnetic storms over two solar cycles

Severe storms data set (1996-2019) Lotz, Grant, Davel (2022). This data set is curated from 1-minute time resolution OMNI [4] and INTERMAGNET [7] data, spanning the period 1996 - 2019. It consists of all geomagnetic storms that reached minimum SYM-H (Symmetric-H index) of < -100 nT. We classified these as "severe" storms. There are 115 such events in the period 1996 - 2018. No severe storms detected between 2007-2010 or in 2019. Each file in the set contains the events in that year (YYYY) in the format "severe_YYYY.pickle". The geomagnetic storms are identified by the procedure described in [1], with thresholds -100 nT and -20 nT (see [1] for further detail). The data sets are Pandas "dataframes" [2], saved in the Python "pickle" format [3]. Each dataframe contains 23 variables, listed in the table below, with their description and unit. Fourteen of the parameters are solar wind plasma and magnetic field parameters from the High Resolution OMNI data set [4]. There are 7 geomagnetic variables: one is the global Sym-H index, four are H-component geomagnetic observations from Hermanus, South Africa (HER: 34.4 S, 19.22 E) and Abisko, Sweden (ABK: 68.35 N, 18.82 E) and their time derivatives two are the e_h index [5] calculated at HER and ABK Finally, we list the time shift applied to each data point to shift to the bow shock nose (described for OMNI at [6]) and a string identifier for each geomagnetic storm. Variables included in the dataframes. # Name Description Unit 1 time_shift Time shift applied to shift solar wind parameters to bow shock s 2 Bt Magnitude of interplanetary magnetic field (IMF) nT 3 Bx X-component of IMF nT 4 By_GSE Y-component of IMF (GSE coordinates) nT 5 Bz_GSE Z-component of IMF (GSE coordinates) nT 6 By_GSM Y-component of IMF (GSM coordinates) nT 7 Bz_GSM Z-component of IMF (GSM coordinates) nT 8 Vsw Bulk solar wind speed km/s 9 Vx X-component of solar wind km/s 10 Vy Y-component of solar wind km/s 11 Vz Z-component of solar wind km/s 12 Np Proton number density in solar wind plasma #/cc 13 Temp Temperature of solar wind plasma K 14 Pd Dynamic or flow pressure of solar wind plasma nPa 15 E_field Solar wind electric field mV/km 16 SymH Symmetric-H index of the geomagnetic field nT 17 HER_H H-component of the geomagnetic field at Hermanus nT 18 HER_dHdt Time derivative of HER_H nT/min 19 HER_eh e_h index at HER nT/min 20 ABK_H H-component of the geomagnetic field at Abisko nT 21 ABK_dHdt Time derivative of ABK_H nT/min 22 ABK_eh e_h index at ABK nT/min 23 Storm_ID String identifier of the geomagnetic storm - References Lotz, S. I., & Danskin, D. W. (2017). Space Weather, 15, 1347– 1356. doi.org omniweb.gsfc.nasa.gov pandas.pydata.org docs.python.org Wintoft, P., Wik, M., & Viljanen, A. J. Space Weather Space Clim., 5, A7 (2015). dx.doi.org omniweb.gsfc.nasa.gov intermagnet.org