The limitations of using vertical cutoff rigidities determined from the IGRF magnetic field models for computing aircraft radiation dose.

Vertical cutoff rigidities derived from the International Geomagnetic Reference Fields (IGRF) are normally used to compute the radiation dose at a specific location and to organize the radiation dose measurements acquired at aircraft altitudes. This paper presents some of the usually ignored limits on the accuracy of the vertical cutoff rigidity models and describes some of the computational artifacts present in these models. It is noted that recent aircraft surveys of the radiation dose experienced along specific flight paths is sufficiently precise that the secular variation of the geomagnetic field is observable.