Geomagnetic and Atmospheric Modulation of Galactic Cosmic Rays: A Comparative Analysis of Tashkent and Almaty Neutron Monitor Observations

Ground-based neutron monitor observations are essential for investigating long-term galactic cosmic ray (GCR) variability, but their measurements are significantly affected by geomagnetic shielding and atmospheric conditions. This study presents a comparative analysis of GCR observations from the Tashkent (Uzbekistan) and Almaty (Kazakhstan) neutron monitor stations to evaluate the combined effects of geomagnetic cutoff rigidity (Rc) and atmospheric pressure. Long-term datasets were analyzed using station-specific barometric corrections and regression methods. The results show that the high-altitude Almaty station (3340 m; Rc≈6.4–6.7 GV) is more sensitive to lower-energy cosmic rays than the lower-altitude Tashkent station (400–500 m; Rc≈7.3–7.5 GV). A strong inverse relationship was found between atmospheric pressure and neutron monitor intensity, with barometric coefficients of β=(0.668±0.016)%mbar−1 for Almaty and β=(0.686±0.016)%mbar−1 for Tashkent. Correlation analysis of the atmospheric-pressure dependence yielded R≈0.92–0.95, whereas the multifactor regression analysis used for atmospheric correction yielded a coefficient of determination of R2≈0.97. These findings demonstrate that station-specific atmospheric corrections and consideration of geomagnetic conditions significantly improve the accuracy of long-term neutron monitor observations for GCR and regional space-weather studies.