Introduction of meteorological corrections into meson monitor data

A set of regression calculations has been carried out correlating the daily average meson intensity with barometric pressure, atmospheric temperature and neutron monitor intensity. Two complete years of data from a plastic scintillator meson monitor and from a large neutron monitor, operated in a constant-temperature laboratory at Deep River, were used. An exhaustive list of atmospheric temperature parameters was investigated: ground temperature; the heights of the 100, 200, 300 and 400 mb isobaric levels; some recommended combinations of isobaric level heights and temperatures; formulations due to Dorman and to Maeda using temperatures at all the standard isobaric levels; a number of arbitrarily distorted versions of these formations including those recommended by Wada and by Lindgren. It was found that the formulations of Dorman, of Maeda, and of Wada were almost indistinguishable in terms of the available data and yielded by far the best fit among the variables. However, none of the temperature parameters tried was able to fit the day-to-day and the seasonal temperature effects equally well with a single regression coefficient. Use of the following partly empirical temperature parameter resolved the difficulty for routine correction of the Deep River data: 1.045 T(j) + 0.215 T(j), where T(j) is Maeda's temperature correction for day j and T(j) is its 31-day running average centered on day j.