A study of the diurnal and semi-diurnal variations of cosmic ray nucleonic intensity at Victoria for the period September 1964-August 1966
Date
1967
Authors
Ng, Janet Wai-Sim
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Abstract
An analysis is given of the solar daily variation of cosmic ray nucleonic intensity recorded by the neutron monitors at Victoria and other stations during 1965. The variabilities of amplitude and time of maximum of daily variation of cosmic radiations at Victoria have been investigated on a day-to-day basis from September 1964 to August 1966.
A geomagnetic-latitude dependence of the diurnal hour of maximum is observed and a barometric coefficient of -0.74 per cent per millibar is obtained from semi-diurnal components of pressure and uncorrected neutron counts; these are in agreement with other workers. Day-to-day analysis of diurnal variation of corrected neutron counts at Victoria for the period September 1964 to August 1966 reveals that there exists enhanced amplitudes of diurnal variation in preferred directions, and in a few instances those amplitudes can be associated with cosmic ray storms. There is a general increase in diurnal amplitudes in the summer months with no corresponding increase in the daily total cosmic ray counting rate. Finally, the mean diurnal hour of maximum is found to be 16 hours local time.
An attempt has been made to find out if the semiĀdiurnal variation is just the residual error after correction for pressure, but without satisfactory result.