What fraction of the outer radiation belt electron flux was lost to the atmosphere during the dropout event on the St Patrick’s Day storm of 2015?

Gokani, Sneha

What fraction of the outer radiation belt electron flux was lost to the atmosphere during the dropout event on the St Patrick’s Day storm of 2015?

Thursday, 8 March 2018

Lakehouse (Hotel Quinta da Marinha)

Sneha A Gokani, Indian Institute of Geomagnetism, New Mumbai, India, Michael Kosch, South African National Space Agency, Hermanus, South Africa, Mark A. Clilverd, British Antarctic Survey, Cambridge, United Kingdom, Craig J Rodger, University of Otago, Department of Physics, Dunedin, New Zealand, Rajesh Singh, Indian Inst of Geomagnetism, Allahabad, India, Donald W Danskin, Natural Resources Canada, Geomagnetic Laboratory, Ottawa, ON, Canada and Steve Marpel, Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK, Physics, Lancaster, United Kingdom

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Abstract:

During the large geomagnetic storm of 17 March 2015, REPT/RBSP measurements show a deep dropout of >1 MeV electrons at L>4. In this paper we investigate the fraction of the flux lost to the atmosphere. We combine RBSP measurements with ground-based subionospheric VLF from the AARDDVARK network. Strong amplitude and phase perturbations are observed in the NAA signal received at Seattle, and the NDK signal received at St. Johns, Canada. Both propagation paths monitor L≈4 in the MLT night sector. Amplitude decreases of up to ~ 12 dB and phase increases of up to ~180° are observed during the time of the flux dropout event. No VLF perturbations are seen in equivalent paths on the MLT dayside. The night time VLF signal is modelled using LWPC and Wait ionospheric parameters; reflection height (H’ in km) and sharpness factor (β in km^-1) are calculated to infer the induced changes in D-region ionospheric electron density. The observations will be discussed in detail during the conference.