2026/02/12 by S. Paul, K.P. Arunbabu, K. P. Arunbabu +20 · 1 voice
Physics and Astronomy · Earth and Planetary Sciences · #Astrophysics and Cosmic Phenomena #Solar and Space Plasma Dynamics #Earthquake Detection and Analysis
paper · pdf · doi:10.1016/j.astropartphys.2026.103252
We study the influence of variations in the upper atmospheric temperature and interplanetary magnetic field on the cosmic ray induced atmospheric muon flux measured by the GRAPES-3 experiment over 22 years (2001--2022) of data; spanning three solar cycles: the declining phase of Solar Cycle 23, the full Cycle 24, and the rising and maximum phases of Cycle 25. Located in Ooty- India, the GRAPES-3 large area (560 m2) muon telescope detects ∼4 billion muons daily above 1 GeV, with an angular resolution of ∼4^∘, enabling a statistical precision <0.01% on the hourly muon rate. After accounting for the effect of atmospheric pressure variations, we compare this data with the upper atmospheric temperature inferred from NASA's MERRA-2 dataset as well as magnetic field data from the ACE and WIND spacecraft at Lagrange point L1. A simultaneous iterative fitting method employing Fast Fourier Transforms and a narrow band-pass filter reveals the temperature and magnetic field coefficients to be αT=- 0.2241 ± 0.04 (stat.) ± 0.0220 (syst.) % K-1 and γM=- 0.574 ± 0.027 (stat.) ± 0.011 (syst.) % nT-1, respectively, for an assumed hadronic attenuation length λ=120 g cm-2, underscoring the potential of the GRAPES-3 muon telescope to serve as a real time monitor of the upper atmospheric temperature or interplanetary magnetic field.