Effect of Local Time Dependence on the Observation of an Anisotropic Solar CosmicRay Flux by Aircraft

摘要

The distribution of the high energy solar flare particle radiation over the earthis not uniform, but is a complex phenomena involving the latitude and longitude of locations on the earth. The latitude effect relates to the earth's geomagnetic shield and the longitude effect relates to local time. For anisotropic solar cosmic ray events the maximum particle flux is always along the interplanetary magnetic field direction, sometimes called the angle of the Archimedean spiral path from the sun to the earth. At the position of the earth in space, the average direction of the interplanetary magnetic field is about 45 deg west of the earth-sun line. During an anisotropic solar cosmic ray event, any location on the earth having an asymptotic cone of acceptance viewing into the interplanetary magnetic field direction will observe the largest flux (when adjustments are made for the magnetic latitude effect). To relate this to aircraft routes, any aircraft at mid or high latitude locations where the asymptotic cone of acceptance is viewing into the interplanetary magnetic field direction will also be subjected to the highest flux during an anisotropic solar cosmic ray event. For anisotropic solar cosmic ray events that may occur during normal quiescent conditions, the maximum flux is likely to be observed at 06 hours local time.