Statistical analysis of infrasound signatures in airglow observations: Indications for acoustic resonance

Abstract

The detection of infrasonic signals in temperature time series of the mesopause altitude region (at about 80-100 km) is performed at the German Remote Sensing Data Center of the German Aerospace Center (DLR-DFD) using GRIPS instrumentation (GRound-based Infrared P-branch Spectrometers). Mesopause temperature values with a temporal resolution of up to 10 seconds are derived from the observation of nocturnal airglow emissions and permit the identification of signals within the long-period infrasound range. Spectral intensities of wave signatures with periods between 2.5 and 10 minutes are estimated applying the wavelet analysis technique to one minute mean temperature values. Selected events as well as the statistical distribution of 40 months of observation are presented and discussed with respect to resonant modes of the atmosphere. The mechanism of acoustic resonance generated by strong infrasonic sources is a potential explanation of distinct features with periods between 3 and 5 minutes observed in the dataset.