1. Application of neutron monitor data for assessment of aircrew exposure
Alexander Mishev and Ilya Usoskin
University of Oulu

2. Outline 1. Introduction & Motivation 2. Method for GLE analysis
3. Assessment of effective/ambient dose equivalent at flight altitudes during strong SEPs
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 strong
SEPs e.g. GLEs and sub-GLES
1. Assessment of primary GLE characteristics: spectrum & anisotropy
using the information from NMs
2. Computation of ambient dose equivalent and/or effective dose using the
derived SEP spectra

4. Current status of the global NM network

5. Method for GLE analysis
The NM count rate modeling

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

7. The GLE analysis procedure
1. Computation of asymptotic directions and cut-off rigidity of NM stations:
Simulation of particle propagation in a model magnetosphere.
2. Initial guess of the inverse problem
3. Application of optimization method:
(energy spectrum, anisotropy axis direction, pitch-angle distribution)

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

9. Inverse, constrained nonlinear problem Levenberg Marquardt with
variable regularization

10. GLE 67 on 2 November 2003

11. PAD distribution during GLE 71, 17 may 2012

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

13. Sub –GLE analysis

14. Derived set of sub-GLE rigidity spectra 29.10.2015

15. 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.

16. Effective dose
Effective dose yield function

17. Effective dose yield function at 35 kft

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

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

21. Maximal effective dose rate during GLEs
GLE Date Effective dose rate
μSv h-1
μSv h-1
02.11/ μSv h-1
mSv h-1
μSv h-1
μSv h-1

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

24. THANK YOU