Abstract:
Relativistic electrons cause internal charging on satellites and are a significant space weather hazard. In this study we analyse approximately 20 years of data from the US Global Positioning System (GPS) satellite NS41 to determine the conditions associated with the largest daily averaged fluxes of E = 2.0 MeV relativistic electrons. The largest flux events at L = 4.5 and L = 6.5 were associated with moderate to strong coronal mass ejection (CME)-driven geomagnetic storms. However, the majority of the fifty largest flux events at L = 4.5 (30 out of 50) and L = 6.5 (37 out of 50) were associated with high speed solar wind streams from coronal holes. Both solar drivers are thus very important for relativistic electron flux enhancements in GPS orbit. The 1 in 3 year flux level was not exceeded following any of the fifteen largest geomagnetic storms as monitored by the Dst index (Disturbance storm time index), showing that the largest geomagnetic storms, most often associated with extreme space weather, do not result in significantly larger relativistic electron flux events in GPS orbit.
The datasets include a summary plot of the month associated with the largest flux of 2.0 MeV electrons in GPS orbit during the study period (Figure 1) and a summary plot of the month associated with the largest geomagnetic storm during the study period (Figure 2). The fifty largest 2.0 MeV flux events at L = 4.5 as a function of the minimum Dst of the associated storm are provided in Figure 3.csv, the peak 2.0 MeV electron fluxes associated with the fifteen largest geomagnetic storms at L = 4.5 as a function of the minimum Dst of each of the storms are provided in Figure 4.csv, and the fifty largest 2.0 MeV flux events at L = 4.5 and the sunspot number are provided as a function of time in Figure 5_events.csv and Figure_5_sunspots.csv respectively. The characteristic widths of the fifty largest flux enhancements at L = 4.5 and L = 6.5 are provided in Figure 6.csv. Finally, the fifty largest 2.0 MeV flux events at L = 6.5 as a function of the minimum Dst of the associated storm are provided in Figure 7.csv, the peak 2.0 MeV electron fluxes associated with the fifteen largest geomagnetic storms at L = 6.5 as a function of the minimum Dst of each of the storms are provided in Figure 8.csv, and the fifty largest 2.0 MeV flux events at L = 6.5 and the sunspot number as a function of time are provided in in Figure 9_events.csv and Figure_9_sunspots.csv respectively.
The research leading to these results has received funding from the Natural Environment Research Council (NERC) grants NE/V00249X/1 (Sat-Risk), NE/X000389/1 and NE/R016038/1.
Keywords:
Geomagnetic Storms, Medium Earth Orbit, Relativistic electrons
Meredith, N., Cayton, T., & Cayton, M. (2024). Strong relativistic electron flux events in GPS orbit (2000 - 2020) (Version 1.0) [Data set]. NERC EDS UK Polar Data Centre. https://doi.org/10.5285/dd8dee98-b75e-4b2f-a002-3f00bcc29d35
| Access Constraints: | None |
|---|---|
| Use Constraints: | Data supplied under Open Government Licence v3.0 http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/. |
| Creation Date: | 2024-09-16 |
|---|---|
| Dataset Progress: | Complete |
| Dataset Language: | English |
| ISO Topic Categories: |
|
| Parameters: |
|
| Personnel: | |
| Name | UK Polar Data Centre |
| Role(s) | Metadata Author |
| Organisation | British Antarctic Survey |
| Name | Dr Nigel Meredith |
| Role(s) | Investigator, Technical Contact |
| Organisation | British Antarctic Survey |
| Name | Thomas E Cayton |
| Role(s) | Investigator |
| Name | Michael D Cayton |
| Role(s) | Investigator |
| Name | Prof Richard Horne |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Parent Dataset: | N/A |
| Reference: | Meredith, N. P., Cayton, T. E., Cayton, M. D., & Horne, R. B. (2024). Strong relativistic electron flux events in GPS orbit, under review. | |
|---|---|---|
| Quality: | The particle data have been calibrated and quality-controlled prior to release. | |
| Lineage: | The data used in this study were collected by the Burst Detector Dosimeter IIR (BDD-IIR) on board the US GPS satellite NS41. The data is publicly available from http://www.ngdc.noaa.gov/stp/space-weather/satellite-data/satellite-systems/gps/data/ns41. Full details of the subsequent analysis are given in Meredith et al. (2024). | |
| Temporal Coverage: | |
|---|---|
| Start Date | 2000-12-10 |
| End Date | 2020-07-25 |
| Location: | |
| Location | Magnetosphere (other) |
| Detailed Location | Circular orbit of 20,200 km. Inclination: 55 degrees |
| Data Collection: | BDD-IIR is a multi-purpose silicon detector system. It features 8 individual channels of a "shield/filter/sensor" design that permits the detector to sample roughly half the celestial sphere while at the same time shielding the silicon sensor elements from most of the incident particle flux. |
|---|
| Distribution: | |
|---|---|
| Distribution Media | Online Internet (HTTP) |
| Distribution Size | 576 kB |
| Distribution Format | ASCII |
| Fees | N/A |
| Data Storage: | There are 33 CSV files contributing to the figures in the associated paper (in review) Figure 1: Summary plot of the NS41 Burst Detector Dosimeter IIR E = 2.0 MeV electron flux for April 2010, (a-f) at L = 7.0, 6.5, 6.0, 5.5, 5.0, and 4.5, respectively. The dotted lines in panels a-f represent the 1% exceedance level at each value of L. Figure 2: Summary plot of the NS41 Burst Detector Dosimeter IIR E = 2.0 MeV electron flux for November 2003, (a-f) at L = 7.0, 6.5, 6.0, 5.5, 5.0, and 4.5, respectively. The dotted lines in panels a-f represent the 1% exceedance level at each value of L. Figure 3: The fifty largest E = 2.0 MeV daily average electron flux events as a function of storm strength as monitored by the Dst index. CME-driven storms are coded red and high speed stream driven storms are coded orange. The dashed, dot-dashed, and solid purple lines represent the 1 in 2, 1 in 10 and 1 in 100 year flux levels respectively. Figure 4: The maximum E = 2.0 MeV daily average electron fluxes at L = 4.5 associated with the largest fifteen storms as monitored by the Dst index. The dashed, dot-dashed, and solid purple lines represent the 1 in 2, 1 in 10 and 1 in 100 year flux levels respectively. Figure 5: (a) The fifty largest E = 2.0 MeV daily average electron flux events at L = 4.5 as a function of time. The dashed, dot-dashed, and solid purple lines represent the 1 in 2, 1 in 10 and 1 in 100 year flux levels respectively; (b) the 27 day average sunspot number as a function of time. Figure 6: The distribution of the full width half maxima (FWHM) for the fifty largest flux events at L = 4.5 (red trace) and L = 6.5 (blue trace). The FWHM, on the x axis, is measured in days and the number of events are plotted on the y axis. Figure 7: The fifty largest E = 2.0 MeV daily average electron flux events at L = 6.5 as a function of storm strength as monitored by the Dst index. CME-driven storms are coded red and high speed stream driven storms are coded orange. The dashed, dot- dashed, and solid purple lines represent the 1 in 2, 1 in 10 and 1 in 100 year flux levels respectively. Figure 8: The maximum E = 2.0 MeV daily average electron fluxes at L = 6.5 associated with the largest fifteen storms as monitored by the Dst index. The dashed, dot-dashed, and solid purple lines represent the 1 in 2, 1 in 10 and 1 in 100 year flux levels respectively. Figure 9: (a) The fifty largest E = 2.0 MeV daily average electron flux events at L = 6.5 as a function of time. The dashed, dot-dashed, and solid purple lines represent the 1 in 2, 1 in 10 and 1 in 100 year flux levels respectively; (b) the 27 day average sunspot number as a function of time. |