Abstract
In the frame of the European H2020 project ARISE, a short wave infrared (SWIR) InGaAs camera has been operated at the Haute-Provence Observatory, during a night that corresponds to the peak of Geminid meteor shower to investigate infrasound associated with meteor arrivals. This camera allows continuous observations during clear-sky nighttime of the OH airglow layer centered at 87 km. These observations were collocated with Rayleigh lidar measurements providing vertical temperature profiles from the lower stratosphere to the altitude of the OH layer around the mesopause. Spectral analysis of OH images did not allow to detect infrasound associated with meteor trails, however it reveals a peak corresponding to infrasound signals in the frequency band of those produced by ocean swell. Infrasound wave activity observed from ground-based microbarometers as well as the OH camera, appear to be modified with the presence of a temperature inversion described by Rayleigh lidar. Indeed, there is a difference in energy related to infrasonic activity between the first part of the night during the temperature inversion and after the inversion.
Highlights
Infrasonic waves are sub-audible sound waves with frequencies below 20 Hz down to 0.003 Hz
In this work we have shown that the radiation emitted by the OH molecule can be disturbed by the propagation of perturbations of the order of few seconds, in particular infrasound generated by ocean swells that have a specific frequency signature around 0.2 Hz
It seems we were not able to detect infrasounds generated by meteor trails
Summary
Infrasonic waves are sub-audible sound waves with frequencies below 20 Hz down to 0.003 Hz. A global network of microbarometers is being deployed within the CTBTO (Preparatory commission for the Comprehensive Nuclear-Test-Ban Treaty Organization) framework to detect any nuclear explosion Such sensors are sensitive to all sort of sources of infrasounds while their propagation are modified during their transit into the atmosphere and are sensitive to wind and temperature fluctuations (LePichon et al, 2018). Other studies have analyzed the OH temperature modulations caused by the propagation of infrasound with periods of several minutes using the GRIPS (GRound-based Infrared P-branch Spectrometer) measurement system (Bittner et al, 2010; Pilger and Bittner, 2009) but the present study is about the perturbation of OH radiation caused by the propagation of infrasound with periods of a few seconds using a short-wave infrared camera During this campaign, a mesospheric inversion inducing a large temperature disturbance was present, allowing to provide preliminary results about the influence of the mesospheric state on infrasound propagation
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