Atmospheric effects on secondary cosmic ray muons observed by multi-wire muon detector at a high cutoff rigidity station

Abstract

In October 2017, a multi-layer small multi-wire (MW) detector for cosmic ray (CR) muon measurements was installed at King Abdulaziz City for Science and Technology (KACST), Riyadh, Saudi Arabia (Rc = 14.4 GV). This detector is considered to be the first of its kind used for long term CR measurements. In this study, CR data collected from KACST-MW detection system and radiosonde measurements were used to investigate the effect of atmospheric pressure, ground temperature, height of the muon production layer, temperature at that layer, and temperature weighted by atmospheric mass, on CR muons. Regression analyses between the observed muon count rate and these variables were carried out and the corresponding coefficients were obtained and used to correct the observed muon count rate for the temporal variation of these variables. The effect of the atmospheric pressure was conducted first and used to correct the data for this effect. The pressure corrected count rate is anti-correlated with the height of muon production, ground temperature, and atmospheric mass-weighted temperature. On the other hand, the temperature at the muon production layer is positively correlated with the muon count rate. The obtained results from this study are in good agreement with those reported by several researchers. Taking advantages of the relationship between the detected CR muons and the temperature at the muon production layer (stratospheric temperature), this relationship is inverted to calculate this temperature from muon observations. The proposed technique provides excellent predictability of the stratospheric temperatures.