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This study uses infrasound detections from a repetitive source to estimate the effect of the atmosphere's temporal variability on infrasound. While a previous paper focused on infrasound propagation through the troposphere to a distance of 54 km, this study uses stratospheric returns detected 256 km from the source. Based on source‐receiver pairs, the empirical Green's function is calculated every 20 s for 52 events; these allow generating a set of synthetic signals where variations are ascribed to variation in the atmosphere. In addition, observations are compared with numerical simulation results based on realistic atmospheric conditions. Results show that variations of stratospheric infrasound signals are observed over timescales ranging from tens of seconds to minutes and have dominant periods ranging from tens to hundreds of seconds. These results motivate using infrasound to probe short temporal changes in the middle atmosphere and study their underlying phenomena. Key Points: Evidence for temporal (minute‐scale) variability of the middle atmosphere is observed by infrasoundShort temporal dynamics affects infrasonic phases, waveforms, propagation time, and energyThe same atmospheric phenomena drive variations of infrasonic correlation coefficient and energy [ABSTRACT FROM AUTHOR]

Infrasound monitoring is used in the forensic analysis of events, studying the physical processes of sources of interest, and probing the atmosphere. The dynamical nature of the atmosphere and the use of infrasound as a forensic tool lead to the following questions; (1) what is the timescale of atmospheric variability that affects infrasonic signals? (2) how do infrasound signals vary as a function of time? This study addresses these questions by monitoring a repetitive infrasound source and its corresponding tropospheric returns 54 km away. Source‐receiver empirical Green's functions are obtained every 20 s and used to demonstrate the effect of atmospheric temporal variability on infrasound propagation. In addition, observations are compared to predicted simulated signals based on realistic atmospheric conditions. Based on 127 events over 3 days, it is shown that infrasound properties change within tens of seconds. Particularly, phases can appear and disappear, the propagation time varies, and the signals' energy fluctuates. Such variations are attributed to changes in temperatures and winds. Furthermore, atmospheric models can partly explain the observed changes. Therefore, this study highlights the potential of high temporal infrasound‐based atmospheric sounding. Key Points: Evidence for temporal (minute‐scale) variability of the lower troposphere is observed by infrasoundShort temporal dynamics affects infrasonic phases, waveforms, propagation time, and energy [ABSTRACT FROM AUTHOR]