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Space Weather Nowcast of Atmospheric Ionizing Radiation for Aviation Safety
• NAIRAS Team– Chris Mertens (PI)
– Kent Tobiska (Co-I), Space Environment Technologies, Inc, Pacific Palisades, CA.
– Brian Kress (Co-I), Dartmouth College, Hanover, NH.
– Stan Solomon (Co-I), NCAR/HAO, Boulder, CO.
– Mike Wiltberger (Co-I), NCAR/HAO, CO.
– Joe Kunches (Collaborator), NOAA/Space Environment Center, Boulder, CO.
– Barbara Grajewski (Collaborator), CDC/NIOSH, Cincinnati, OH
– Steve Blattnig, (Collaborator), LaRC RT/Space Radiation Group
– John Norbury (Collaborator), LaRC RT/Space Radiation Group
– Tony Slaba (Collaborator), LaRC RT/Space Radiation Group
NASA Applied Science Weather Program ReviewBoulder, Colorado, November 19, 2008
Outline
• Project Overview
• Summary of Milestones
• Discussion of Milestones
• Publications
• Summary
Earth System Models
Radiation Dose Rates:
AIR (parametric)
HZETRN (physics-based)
Near-Earth Space Environment
•Badhwar/O’Neill GCR Model
•Empirical Cutoff Rigidity
( IGRF+T05)
•Physics-based Cutoff Rigidity
(LFM/CMIT+SEP-trajectory)
Earth System Models
Radiation Dose Rates:
AIR (parametric)
HZETRN (physics-based)
Near-Earth Space Environment
•Badhwar/O’Neill GCR Model
•Empirical Cutoff Rigidity
( IGRF+T05)
•Physics-based Cutoff Rigidity
(LFM/CMIT+SEP-trajectory)
Value & Benefitsto Society
Improvements in the decision-making, decisions, and actions
First-ever, data-driven, real-time prediction of biologically harmful
radiation exposure levels at commercial airline altitudes
Quantitative and qualitative benefits from the improved
decisions
Comprehensive database of radiation dose rates to formulate recommended annual and career limits to ionizing radiation exposure
Comprehensive database of radiation dose rates for airlines to assess cost/risk of polar routes
Real-time prediction of radiation exposure levels to enable optimal balance between airline cost and air traveler health risk during solar storm (SEP) events
Improve understanding of biological effects of atmospheric ionizing radiation on aircrew and passengers through collaboration of epidemiological studies by NIOSH
Value & Benefitsto Society
Improvements in the decision-making, decisions, and actions
First-ever, data-driven, real-time prediction of biologically harmful
radiation exposure levels at commercial airline altitudes
Quantitative and qualitative benefits from the improved
decisions
Comprehensive database of radiation dose rates to formulate recommended annual and career limits to ionizing radiation exposure
Comprehensive database of radiation dose rates for airlines to assess cost/risk of polar routes
Real-time prediction of radiation exposure levels to enable optimal balance between airline cost and air traveler health risk during solar storm (SEP) events
Improve understanding of biological effects of atmospheric ionizing radiation on aircrew and passengers through collaboration of epidemiological studies by NIOSH
Predictions/Forecasts
Observations, Parameters & Products
Earth Observations
Near-Earth Space Environment
NASA/ACE
NASA/HEAO-3
NOAA/GOES
Assimilated Atmospheric
Atmospheric Depth (NCAR/NCEP)
Ground-Based
Neutron Count Monitors
Earth Observations
Near-Earth Space Environment
NASA/ACE
NASA/HEAO-3
NOAA/GOES
Assimilated Atmospheric
Atmospheric Depth (NCAR/NCEP)
Ground-Based
Neutron Count Monitors
Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS)
Ionizing Radiation Nowcast
3-D Dose Equivalent
3-D Differential Flux
NAIRAS Distributed Network System
High-Performance Computer Systems
Server Interface
Operational and Archival
Databases
Differential Particle Flux
HZE Particles (Z=5-26)
Light-Ions (Z=1-4)
Neutrons
Pions and Muons
Electromagnetic Cascasde Particles
Ionizing Radiation Nowcast
3-D Dose Equivalent
3-D Differential Flux
NAIRAS Distributed Network System
High-Performance Computer Systems
Server Interface
Operational and Archival
Databases
Differential Particle Flux
HZE Particles (Z=5-26)
Light-Ions (Z=1-4)
Neutrons
Pions and Muons
Electromagnetic Cascasde Particles
Decision Support Systems, Assessments,
Management Actions
NAIRAS decision support tool for NOAA/SEC space weather
forecasts, warnings, and advisories
NAIRAS available at NOAA/ADD experimental aviation-related weather
forecasts, observations, and analysis
Specific analyses to support the decision making
Predict real-time radiation exposure at commercial airline altitudes (includes background GCR and SEP events)
Provide accumulated radiation exposures for representative set of domestic, international, and polar routes
Specific Decisions / Actions
Limit aircrew flight hours to within recommended annual and career limits
Alter route and/or altitude during SEP events
Decision Support Systems, Assessments,
Management Actions
NAIRAS decision support tool for NOAA/SEC space weather
forecasts, warnings, and advisories
NAIRAS available at NOAA/ADD experimental aviation-related weather
forecasts, observations, and analysis
Specific analyses to support the decision making
Predict real-time radiation exposure at commercial airline altitudes (includes background GCR and SEP events)
Provide accumulated radiation exposures for representative set of domestic, international, and polar routes
Specific Decisions / Actions
Limit aircrew flight hours to within recommended annual and career limits
Alter route and/or altitude during SEP events
Real-time Neutron Monitor Data
(e.g., IZMIRAN and LOMICKY)
Physics-Based Atmospheric Ionizing Radiation Dosimetry
HZETRN +
Dosimetry
Fit to Climax NMC
Badhwar+O’Neill GCR Model
NOAA GOES Data
Spectral Fitting
Magnetospheric Magnetic Field
(e.g., T05)Effects on
Cutoff Rigidity
Cutoff Rigidity (IGRF)
Atmospheric Density
NCAR/NCEP Reanalysis
Atmospheric Doseand Dose Equivalent
NASA/ACE SolarWind and IMF Data
Important Milestones Achieved(1)
• NAIRAS operational distributed network system– System designed and implementation underway– Model I/O requirements and sources defined– Redundancy established for all input data products
• Operational HZETRN– Automated canonical radiation flux and dose rate calculations
performed on 2-D (rigidity, atmospheric depth) grid– Preliminary coupling to SEP fluence spectral fit model, cutoff
rigidity model, and NCAR/NCEP Reanalysis Data (air temperature and geopotential height)
– Working on including directional anisotropy in rigidity, flux, and subsequent dose predictions
• Directionally-coupled low-energy neutron transport– Tony Slaba’s PhD thesis and post-doc work (ODU)– Validated against Monte Carlo Codes (FLUKA and HET-HEADS) for
September 1989 SEP event – Now Implemented in NAIRAS– Factor 4 greater doses rates in polar cap region
Important Milestones Achieved(2)
• SEP proton and alpha fluence spectral fitting to ACE/GOES – Version 1 operational algorithm implemented with
preliminary testing – Funded two students through the Langley Aerospace
Research Summer Scholars (LARSS) Program to contribute to this work
• Analysis of Halloween 2003 SEP events– Storm-time geomagnetic effects on cutoff rigidities critical
Magnetospheric effects reduce mid- to high-latitude cutoffs by as much as a 1 GV.
Increase total dose by as much as a factor of 4
– ICRP prenatal exposure exceeded during typical commercial polar routes
NAIRAS Operational Distributed Network SystemNext Slide
NAIRAS Operational Distributed Network System
NAIRAS Models and I/O DefinitionsNext Two Slides
SEP Proton and Alpha Fluence Spectral FittingNext Five Slides
SEP Event 3 From Previous SlideEvent-Averaged Analysis for Event 3 in Next Section
HZETRN SEP Atmospheric Transport
• Incident SEP spectra: non-linear least-squares spectral fit to NOAA/GOES and NASA/ACE
• Double power-law spectrum [Mewaldt, 2003]
0 0
( )
0 0
/ exp( / ) for ( )
/ ( ) exp( ) for ( ) ,
a
b ab
b a
b a a b b a
dJ dE CE E E E E
dJ dE CE E E E
Analysis of Halloween 2003 SEP EventNext Six Slides
High-latitude routes can exceed ICRP prenatal limit (1 mSv)
ICRP annual limit (20 mSv)
Flight Path
Dose Eq.T05S(mSv)
Dose Eq.T05Q(mSv)
Dose Eq. IGRF(mSv)
Dose RatioT05S/IGRF
Dose RatioT05S/T05Q
Dose RatioT05Q/IGRF
JFK-LHR .371 0.128 0.092 4.03 2.90 1.39
ORD-ARN .840 .543 .376 2.23 1.55 1.44
ORD-PEK 1.138 .931 .856 1.33 1.22 1.09
Summary of Total Dose Equivalent and Influenceof Geomagnetic Effects
T05S: Tsyganenko (T05) Storm FieldT05Q: Tsyganenko (T05) Quiet Field
ICRP prenatal limit (1 mSv) exceeded
Neglect geomag effects underestimates dose by factor 4
IGRF underestimates geomagquiet condition by ~ 40%
Publications
• Journal of Space Weather (January, 2009)– Geomagnetic effects on high-latitude radiation exposure during a
Halloween 2003 solar energetic particleevent (Mertens et al.) • Journal of Space Weather (January 2009)
– Variations in geomagnetic shielding of energetic solar ions during severe geomagnetic storms (Kress et al.)
• AIAA Paper (AIAA 2008-463, January, 2008)– Influence of space weather aircraft ionizing radiation exposure (Mertens et
al.)
Summary
• Operational distributed network system development on schedule• Operational HZETRN development on schedule• Directionally-coupled, low-energy neutron transport with coupling to
light-ion transport implemented and tested in NAIRAS.• SEP proton and alpha fluence spectral fitting model developed. Initial
testing in progress.• Atmospheric radiation exposure during Halloween 2003 SEP event
exceeded ICRP prenatal exposure limit (1 mSv) for typical polar route. Some high-latitude routes reached ~ 85% of ICRP prenatal limit.
• Neglecting time-dependent geomagnetic storm influences on cutoff rigidity during SEP events significantly underestimates radiation dose from ~ 30% to over a factor of 4
• IGRF field can result in underestimation of high-latitude radiation dose by ~40% for SEP events without accompanying geomagnetic storm
• Two peer-reviewed journal articles in progress. One AIAA paper published.