On the long-term and the altitude dependence of the barometric coefficient for neutron monitors

Abstract

To relate the variations in the secondary nucleonic component recorded by neutron monitors at ground elevation to the variations in the primary cosmic‐ray intensity, the effects of meteorological changes must be properly evaluated and removed from the data. Investigations have shown that the primary meteorological effect for neutron monitors arises from changes in the air mass above the neutron monitor [Simpson et al., 1953; Lockwood and Yingst, 1956; Dorman, 1957]. Insofar as the barometric pressure is a good measure of the average air mass above the station, changes of meteorological origin can then be eliminated by determining the local barometric coefficient. We should emphasize this latter point, particularly for mountain stations where perturbations from high wind speeds can be a problem [Lockwood and Calawa, 1957].