1. 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

2. 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

3. Introduction An important topic of space weather is the assessment3
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

5. Method for GLE analysis
The NM count rate modeling

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

7. Updated NM registration efficiency based on MC simulations

8. Recalculation of NM effective area

9. NM yield function at several depths

10. NM yield function at several depths for oblique events

11. 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)

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

13. Inverse, constrained nonlinear problem
Levenberg Marquardt algorithm using MINPACK

14. PAD distribution during GLE 71, 17 may 2012

15. 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

16. Rigidity spectrum and PAD during GLE 70, 13 December 2006

17. GLE 70 –

18. GLE 70 –

19. 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.

20. Effective dose
Effective dose yield function

21. Effective dose yield function at 35 kft

23. 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)

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

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

26. 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

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

29. 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

30. THANK YOU