Analytical Representations for Characterizing the Global Aviation Radiation Environment Based on Model and Measurement Databases (Invited Presentation)

Two major sources of radiation hazards at commercial aviation altitudes have been known for decades and those are galactic cosmic rays (GCRs) as well as solar energetic particles (SEPs). GCRs are produced outside the solar system in high-energy explosive events and consist mostly of energetic protons slowly modulated by the strength of the Sun’s interplanetary magnetic field (IMF). SEPs come from either solar coronal mass ejections (CMEs) related to flaring events or from IMF shocks. In the latter case fast CMEs plow through a slower solar wind creating a shock front to produce energetic protons. Recently, a third radiation source has been identified that potentially originates from relativistic electron precipitation (REP) associated with the Van Allen radiation belts and have been called radiation clouds although a physical perspective is likely to be flight through a gamma-ray beam. This ensemble radiation field creates safety concerns for aviation. Because of this safety hazard, a broad community is seeking to i) define the requirements for real-time monitoring of the charged particle radiation environment to protect the health and safety of crew and passengers during space weather events; ii) define the scope and requirements for a real-time reporting system that conveys situational awareness of the radiation environment to orbital, suborbital, and commercial aviation users during space weather events; and iii) develop or improve models for the real-time assessment of radiation levels at commercial flight altitudes. While benchmarks for ionizing radiation related to aviation have included characterizing an occurrence frequency of 1 in 100 years and an intensity level at the theoretical maximum for radiation events, it is also important to develop a baseline radiation environment for GCRs, SEPs, and REPs against which events can be compared. We describe functional, analytical baselines for describing the ionizing radiation environment for commercial aviation based on observations and modeling as part of the NAIRAS, ARMAS, and RADIAN programs.