Geomagnetic influence on aircraft radiation exposure during a solar energetic particle event in October 2003

[1] We present initial results from the Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) model during the Halloween 2003 superstorm. The objective of NAIRAS is to produce global, real-time, data-driven predictions of ionizing radiation for archiving and assessing the biologically harmful radiation exposure levels at commercial airline altitudes. We have conducted a case study of radiation exposure during a high-energy solar energetic particle (SEP) event in October 2003. The purpose of the case study is to quantify the important influences of the storm time and quiet time magnetospheric magnetic field on high-latitude SEP atmospheric radiation exposure. The Halloween 2003 superstorm is an ideal event to study magnetospheric influences on atmospheric radiation exposure since this event was accompanied by a major magnetic storm which was one of the largest of solar cycle 23. We find that neglecting geomagnetic storm effects during SEP events can underestimate the high-latitude radiation exposure from nearly 15% to over a factor of 2, depending on the flight path relative to the magnetosphere open-closed boundary.