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.