On the pressure dependence of the cosmic ray intensity recorded by the standard neutron monitor

Pressure coefficients have been determined for some standard neutron monitors at high latitudes for the years 1957-1959 with due regard to variations of primary origin. The following coefficients were obtained: (1) for Murchison Bay and Uppsala α = – 0.710 ± 0.006 per cent/mb; (2) for Resolute, Churchill and Ottawa α = – 0.725 ± 0.005 per cent/mb; (3) for Mawson and Mt. Wellington α = –0.736 ± 0.004 per cent/mb. The differences in a between the three groups of stations are certainly not due to a purely statistical scattering. They probably reflect dissimilarities in the neutron monitors and the pressure recording devices. As a by-product it has proved that for two stations above the latitude knee, the quotient between the pressure corrected daily neutron intensities is remarkably constant in time. It can thus be used as a sensitive indicator of changes in counting rate.