Schillings_et_al_2023_JSWSC.pdf (11.91 MB)
Signatures of wedgelets over Fennoscandia during the St Patrick’s Day Storm 2015
journal contribution
posted on 2023-08-16, 08:39 authored by Audrey Schillings, Laurianne Palin, Gemma E Bower, Hermann J Opgenoorth, Steve E Milan, Kirsti Kauristie, Liisa Juusola, Geoff D Reeves, Mike G Henderson, Larry J Paxton, Mark Lester, Maria Hamrin, Max Van de KampDuring the long main phase of the St Patrick’s Day storm on March 17, 2015, we found three separate enhancements of the westward electrojet. These enhancements are observed in the ionospheric equivalent currents computed using geomagnetic data over Fennoscandia. Using data from the IMAGE magnetometer network, we identified localised field-aligned current (FAC) systems superimposed on the pre-existing ionospheric current system. We suggest that these localised current systems are wedgelets and that they can potentially contribute to a larger-scale structure of a substorm current wedge (SCW). Each wedgelet is associated with a negative BX spike. Each spike is recorded at a higher latitude than the former one and all three are very localised over Fennoscandia. The first spike occurred at 17:34 UT and was observed at Lycksele, Rørvik and Nurmijärvi, the second spike was recorded at 17:41 UT and located at Lycksele and Rørvik, whereas the last spike occurred at 17:47 UT and was observed at Kevo and Abisko. Simultaneous optical auroral data and electron injections at the geosynchronous orbit indicate that one or more substorms took place in the polar ionosphere at the time of the wedgelets. This study demonstrates the occurrence of small and short-lived structures such as wedgelets at different locations over a short time scale, 15 min in this case.
Funding
We thank the institutes who maintain the IMAGE Magnetometer Array: Tromsø Geophysical Observatory of UiT the Arctic University of Norway (Norway), Finnish Meteorological Institute (Finland), Institute of Geophysics Polish Academy of Sciences (Poland), GFZ German Research Centre for Geosciences (Germany), Geological Survey of Sweden (Sweden), Swedish Institute of Space Physics (Sweden), Sodankylä Geophysical Observatory of the University of Oulu (Finland), and Polar Geophysical Institute (Russia). The AE data were retrieved from the OMNIWeb page https://omniweb.gsfc.nasa.gov/form/omni_min.html. We acknowledge the substorm timing list identified by Newell and Gjerloev technique (Newell & Gjerloev, 2011) and by Ohtani and Gjerloev technique (Ohtani & Gjerloev, 2020), the SMU and SML indices (Newell & Gjerloev, 2011); and the SuperMAG collaboration (Gjerloev, 2012). The MIRACLE network is operated as an international collaboration under the leadership of the Finnish Meteorological Institute. INAF-IAPS maintains the ITACA ASC in Ny-Ålesund, and SGO of the University of Oulu maintains the ASC in Sodankylä. AS acknowledges the Swedish National Research Council under grant 2021-06683 and AS, HO and LP acknowledge the Swedish National Space Agency (SNSA) for its financial support under grant 10077/15. GEB is supported by the Science and Technology Facilities Council (STFC), UK, studentship. SM and ML are supported by STFC grant ST/W00089X/1. The work of LJ and KK in this investigation was supported by the Academy of Finland (decision 339329). MH is supported by the Swedish National Space Agency grant 81/17 and the Swedish Research Council grant 2018-03623. LP was sponsored by DMSP Special Sensor Ultraviolet Spectographic Imager (SSUSI) program, contract N00024-13-D-6400, AFOSR grant 26-0201-51-62
History
Author affiliation
School of Physics and Astronomy, University of LeicesterVersion
- VoR (Version of Record)
Published in
Journal of Space Weather and Space ClimateVolume
13Pagination
19Publisher
EDP Openissn
2115-7251eissn
2115-7251Copyright date
2023Available date
2023-08-16Publisher DOI
Language
enPublisher version
Usage metrics
Categories
No categories selectedLicence
Exports
RefWorks
BibTeX
Ref. manager
Endnote
DataCite
NLM
DC