Ubiquitous Occurrences of Multi-scale Layers of Magnetic Reconnection across a Solar Wind Stream Interaction Region at 1 AU: Dataset

The dataset provided herein contains 71 magnetic reconnection exhausts as recorded by the Wind spacecraft during an 8-day period from 1 Jan 2019 to 9 Jan 2019. The interval is centered at a classic stream interaction region (SIR) on 4-5 Jan 2019. The SIR formed as a fast wind stream caught up with a slow wind ahead. In the process a region of plasma and field compression formed between a pair of forward and reverse shocks with a presence of several large-scale crossings of the embedded heliospheric current sheet deep inside the SIR.

Detailed information for the 71 exhausts is available in the ASCII text file [wind_lmn_manual_cs_walen_sb_zenodo.txt]. This information includes start and stop dates and times of the underlying (active) current sheets, their associated LMN unit vectors (base: GSE), times to reproduce Walén predictions as well as average values of associated parameters (B, V, Np, Tp) adjacent each active current sheet (CS). The file also contains the maximum and minimum of several parameters within the exhaust period.

The underlying Wind spacecraft measurements are available from NASA CDAWeb [https://cdaweb.gsfc.nasa.gov/]. The list of 71 events were obtained from an automated survey based on a sliding window technique of 42 different sizes. There are 40 windows at 30 s cadence from dt=30 s to dt=20 min and two windows at 16 s and 44 s.

There are two overview PDF files with 71 pages each for the 71 exhausts.

One file [wind_20190101_20190109_exhaust_opt2_yes_select_sorted_71FINAL_H2MFI.PDF] contains 71 figures with 6 panels showing (from top to bottom) plasma density (Np), proton average temperature (Tp), BL, VL, BM, BN. The individual hybrid-LMN system is given below each plot as Lc, Mc, Nc unit vectors (base: GSE) for each current sheet. Note that this system is based on a cross-product normal (Nc) to the CS. There are three vertical lines. A solid green line corresponds to an optimum, change-over time (topt) between two Walen predictions from the left (leading side) and right (trailing side) of the CS. The CS start and stop times (CS1 and CS2) are shown as the dotted vertical lines. Here, a Walen prediction of the measured VL component of the ion velocity from the WIND 3DP instrument is colored red from both sides of the CS.

The other file [wind_20190101_20190109_exhaust_opt2_yes_select_sorted_71FINAL_H2MFI_cptimes.PDF] contains the 71 event pages with 11 panels: P, Np, Tp, V, B, BL, VL, BM, VM, BN, VN. Here, Pt=Pb+Pp is the sum of the magnetic field pressure (Pb: red) and the proton plasma pressure (Pp: blue). Any deviation from total pressure balance across CSs can most likely be traced to the electron pressure (Pe). Each page also includes Lc, Mc, Nc unit vectors in GSE below the plots. The two red solid lines correspond to CS1 (start) and CS2 (end) times of the exhaust-associated CS. A pair of dotted lines (black and red) before CS1 mark the leading period used to obtain an average magnetic field Bgse1 = [Bx1, By1, Bz1]. A pair of dotted lines (red and black) after CS2 mark the trailing period used to obtain an average Bgse2 = [Bx2, By2, Bz2] for Nc = B1 x B2 / |B1 x B2| cross-product normal determination. Here, a Walen prediction of the measured VL component of the ion velocity from the WIND 3DP instrument is colored in red from the leading (first) side and it is colored in green from the trailing (second) side of the CS. The change-over time (topt) is where the sense of BL and VL changes between being correlated and anti-correlated.

Figure1_Vy.PDF contains two pages of the same Wind parameter data but shown for two separate time periods: 2019 Jan. 01-09 (page 1) and 2019 Jan 04-06 (page 2). The panels for both pages show (a) magnetic field strength (B), (b) Bxgse component of the magnetic field vector, (c) 360 degree azimuthal angle of the ecliptic-plane magnetic field (Bxgse and Bygse) with phi=0 deg and phi=360 deg corresponding to Bxgse>0 and Bygse=0, and phi=90 deg for Bxgse=0 and Bygse>0, (d) solar wind speed, (e) Vygse component of the solar wind velocity with Earth motion Ve=-29.8 km/s subtracted, (f) proton plasma number density (Np), (g) proton average temperature (Tp), (h) logarithm of the ratio of field-parallel electron strahl flux (F21) at 116.1 eV to nearly anti-parallel fluxes (F159), where F21 is a strahl number flux for 18-24o pitch-angles and F159 is a strahl number flux for 156-162o. The two red, horizontal dotted lines in panel (c) mark phi=45 deg and phi=225 deg with a heliospheric magnetic field (HMF) at 45 deg < phi < 225 deg corresponding to an away-sector HMF associated with a parallel electron strahl. There are three red, vertical dotted lines marking a forward shock at 2019-01-04/10:11:20 UT, a stream interface at 2019-01-04/21:48:00 UT, and a reverse shock at 2019-01-05/09:58:00 UT. The two blue, vertical dotted lines at 2019-01-04/17:00 UT and 2019-01-05/01:35 UT mark a magnetic sector boundary between award and toward-directed Bgse as obtained from a change of predominant strahl fluxes (parallel to anti-parallel).

There are three Figure 2 files (Figure2_Bx.PDF, Figure2_By.PDF and Figure2_Bz.PDF). Each PDF contains 8 pages for different time periods with each new page zooming in from an 8-day period (page 1) toward the central magnetic sectory period. Page 8 shows the 11-hour period from 16 UT on 4 Jan to 03 UT on 5 Jan. The three PDFs only differ in terms of panel (b) that either shows the Bxgse, Bygse or Bzgse component of a 3-s cadence magnetic field. From top to bottom: (a) B magnitude, (b) GSE component of Bgse (x, y or z), (c) azimuthal phi-angle of Bgse from Bxgse and Bygse, (d) solar wind speed, (e) Np, (f) Tp, (g) 116 eV strahl flux ratio (parallel over anti-parallel), (h) total number of obtained reconnection exhaust events in subsequent six-hour periods with time stamps at the center of each period (03 UT for 00-06 UT interval etc) and using the Walen t_opt time inside each exhaust interval. The vertical-colored lines mark topt times for all 71 exhausts. Colors represent the dcs=*∆tcs normal width of each active current sheet: 17 exhausts at dcs<50 di shown in light blue, 16 exhausts at 50≤dcs<100 di shown in green, 24 exhausts for 100≤dcs<500 di shown in yellow, 14 exhausts at dcs≥500 di shown in red color. Here, actual CS duration (∆tcs in seconds) and =(VN1+VN2)/2 with VN1 the average normal speed before the CS and VN2 after the CS in km/s, in terms of the average ion inertial length di=c/ωpi next to the CS with c being the speed of light and ωpi the proton plasma frequency (see txt file for ∆tcs, VN1, VN2, di data).

For further details of this solar wind study, we refer to a forthcoming manuscript entitled "Ubiquitous Occurrences of Multi-scale Layers of Magnetic Reconnection across a Solar Wind Stream Interaction Region at 1 AU" by S. Eriksson et al.