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NAIRAS
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Nowcast of Atmospheric Ionizing Radiation System

Current Dose Rates

The NAIRAS model predicts atmospheric radiation exposure from galactic cosmic rays (GCR) and solar energetic particle (SEP) events. GCR particles are propagated from local interstellar space to Earth using an extension of the Badhwar and O'Neill model, where the solar modulation has been parameterized using high-latitude real-time neutron monitor measurements at Oulu, Thule, Lomnicky, and Moscow. During radiation storms, the SEP spectrum is derived using ion flux measurements taken from the NOAA/GOES and NASA/ACE satellites. The cosmic ray particles - GCR and SEP - are transported through the magnetosphere using the CISM-Dartmouth particle trajectory geomagnetic cutoff rigidity code, driven by real-time solar wind parameters and interplanetary magnetic field data measured by the NASA/ACE satellite. Cosmic ray transport through the neutral atmosphere is based on analytical solutions of coupled Boltzmann transport equations obtained from NASA Langley Research Center's HZETRN transport code. Global distributions of atmospheric density are derived from the NCEP Global Forecasting System (GFS) meteorological data.

The current figures below show the NAIRAS prediction of the radiation exposure quantity related to biological risk - Effective dose rate (uSv/hr) - at several altitudes and flight paths. To put the exposure rates into perspective, one chest X-ray is about 100 uSv, and a CT scan is about 8,000 uSv.

 

Dose Rates
Dose rates
Dose Rates
Dose rates
Dose rates
Sode Rates
Dose rates