Alexander Mishev and Ilya Usoskin Application of a full chain analysis using neutron monitor data for space weather studies Alexander Mishev and Ilya Usoskin University of Oulu alexander.mishev@oulu.fi

Outline 1. Introduction & Motivation 2. NM yield function, method for GLE analysis 3. Assessment of effective/ambient dose equivalent at flight altitudes during GLEs 4. Summary

Introduction An important topic of space weather is the assessment 3 Introduction An important topic of space weather is the assessment of aircrew exposure due to CR, specifically during GLEs 1. Assessment of primary SEP parameters: energy spectrum & anisotropy using the information from NMs 2. Computation of ambient dose equivalent and/or effective dose using the derived SEP spectra

Method for GLE analysis The NM count rate modeling

New NM yield function Mishev, Usoskin & Kovaltsov JGR,2013, 118, 2783-2788

Updated NM registration efficiency based on MC simulations

Recalculation of NM effective area

NM yield function at several depths

NM yield function at several depths for oblique events

The GLE analysis procedure 1. Definition of asymptotic viewing cones of the NM stations: Computation of particle trajectory in a model magnetosphere. 2. Calculation of the NM responses: initial guess of the inverse problem 3. Application of a least square procedure (inverse method) primary solar proton parameters: (energy spectrum, anisotropy axis direction, pitch-angle distribution)

Modified power law or exponent PAD – Gaussian like From 5 Up to 14 parameters Express method 3 parameters

Inverse, constrained nonlinear problem Levenberg Marquardt algorithm using MINPACK

PAD distribution during GLE 71, 17 may 2012

GLEs considered for analysis GLE 71 on 17 May 2012 (Mishev et al. JGR 2013) --------------------------------------------------------- --------- GLE 70 on 13 December 2006 (Mishev & Usoskin Solar Physics 2016) GLE 59 on 14 July 2000 (Bastille day event) --------------------------------------------------------- ---------- GLE 69 on 20 January 2005 GLE65-67 October-November 2003

Rigidity spectrum and PAD during GLE 70, 13 December 2006

GLE 70 – 13.12. 2006

GLE 70 – 13.12. 2006

Effective/ambient dose equivalent at flight altitudes New model for effective/ambient dose equivalent estimation based on a full Monte Carlo simulation of SEP and GCR propagation and interaction with the atmospheric molecules. It is based on yield function formalism. Exposure of air crew at flight altitudes of 35 & 50 kft Contribution of GCR to dose rate at high mountain altitude Good agreement with experimental and reference data Extensive GEANT 4 simulation tool PLANETOCOSMICS is used with NRLMSISE 2000 atmospheric model.

Effective dose Effective dose yield function

Effective dose yield function at 35 kft

Relative difference between model and reference data for H Relative difference between model and reference data for H*(10) (Oulu 2015 model and Mertens et al. 2013)

Comparison with measurements and PANDOCA South Germany (Meier et al Comparison with measurements and PANDOCA South Germany (Meier et al. JSWSC 2016)

Comparison with measurements and PANDOCA Norway (Meier et al Comparison with measurements and PANDOCA Norway (Meier et al. JSWSC 2016)

Comparison with measurements at high mountain altitude (Zanini et al Comparison with measurements at high mountain altitude (Zanini et al., JASTP 2005;) HARWELL 3208 Moussala peak Measurements 55±7 nSvh-1 Model 54±5 nSvh-1

Major GLE 69 on 20 January 2005 Ambient dose equivalent H*(10) maximum and after 07:00 ≈ 1.7 mSv h-1 and 0.4 mSv h-1

Conclusion 1. New NM yield function 2. Method for GLE analysis based on NM data 3. Model for effective/ambient dose equivalent estimation at flight altitudes and high mountain 4. Comparison with different models and experimental data - in progress

THANK YOU