Accession Number:

ADA460733

Title:

Solar Radiation Alert System

Descriptive Note:

Final rept.

Corporate Author:

FEDERAL AVIATION ADMINISTRATION OKLAHOMA CITY OK CIVIL AEROMEDICAL INST

Report Date:

2005-07-01

Pagination or Media Count:

13.0

Abstract:

A solar radiation alert SRA system has been developed to continuously evaluate measurements of high-energy protons made by instruments on Geosynchronous Operational Environmental satellites. If the measurements indicate the likelihood of a substantial elevation of effective dose rates at aircraft flight altitudes, the Civil Aerospace Medical Institute issues an SRA to the aviation community via the National Oceanic and Atmospheric Administration Weather Wire Service. This report describes the methodology of the SRA system. A Monte Carlo particle transport code was used to estimate the fluences of secondary particles protons, neutrons, pions, kaons, photons, electrons, and muons in selected energy ranges at specific altitudes. Coefficients to convert particle fluence to effective dose incorporate radiation-weighting factors and tissue-weighting factors recommended by the International Commission on Radiological Protection, except that the radiation-weighting factor for protons was changed from five to two, as recommended by the National Council on Radiation Protection and Measurements. Effective dose rates from solar-proton-induced ionizing radiation in the earths atmosphere at high geomagnetic latitudes were calculated for the solar proton event of 20 January 2005. The event started at 0650 Universal Time, and within 5 minutes, dose rates at 60,000, 40,000, and 30,000 ft relative to mean sea level reached maximum values of 140, 55, and 21 microsieverts per hour, respectively.

Subject Categories:

  • Aircraft
  • Astrophysics
  • Unmanned Spacecraft

Distribution Statement:

APPROVED FOR PUBLIC RELEASE