The South Atlantic Magnetic Field Anomaly and Its Effect on the   Calculated Production of Atmospheric Neutrinos
  The theoretical calculations of the production of neutrinos via cosmic rays incident upon the earth's atmosphere (Barr et al., 1989; Becker-Szendy et al., 1992; Bugaev & Naumov, 1989; Gaisser et al, 1988; Honda et al., 1995) are examined. These calculations use a one-dimensional approximation in the production, transport, and decay of the produced particles. Examined are various additional effects of the earth's magnetic field and the three-dimensional nature of the problem which have the effect of decreasing the calulated ratio of muon neutrinos to electron neutrinos. 
J. Poirier