Sensitivity of the IceCube atmospheric muon rate to decadal trends in the effective atmospheric temperature

Abstract

Decadal changes in the Antarctic stratosphere, generally associated with ozone recovery and shifts in polar circulation, are of broad geophysical interest. However, independent long-term measurements of the atmosphere above the Antarctic interior are scarce. We assess whether the atmospheric muon rate recorded by IceCube could constrain decadal changes in the effective atmospheric temperature, $T_\mathrm{eff}$, a weighted average of temperature through the atmosphere that is most sensitive to the stratosphere. Using public atmospheric reanalysis data and records of cosmic-ray, solar, and geomagnetic variability, we reproduce the measured seasonal response of the IceCube muon rate. We then test whether the same response applies to long-term temperature changes with a different vertical temperature profile. The limiting requirement is detector stability rather than counting statistics: an unmodeled muon rate drift of $1\%\,\mathrm{decade^{-1}}$ would mimic a temperature trend of $2.8\,\mathrm{K\,decade^{-1}}$. The long-term rate must therefore be stable to approximately $0.3\%\,\mathrm{decade^{-1}}$. Within this budget, snow accumulation contributions can be constrained. For a 14-year record, atmospheric variability gives a one-sided 95% CL statistical sensitivity of $1.6\,\mathrm{K\,decade^{-1}}$. Given this sensitivity, the $\sim0.9\,\mathrm{K\,decade^{-1}}$ cooling indicated by the 2011-2025 atmospheric records would become distinguishable after approximately 30 years of measurement.