The impact of a mesospheric temperature inversion on the vertical propagation of gravity waves has been investigated using OH airglow images and ground-based Rayleigh lidar measurements carried out in December 2017 at the Haute-Provence Observatory (OHP, France, 44N). These measurements provide complementary information that allows the vertical propagation of gravity waves to be followed. An intense mesospheric inversion layer (MIL) observed near 60 km of altitude with the lidar disappeared in the middle of the night, offering a unique opportunity to evaluate its impact on gravity wave (GW) propagation observed above the inversion with airglow cameras. With these two instruments, a wave with a 150 min period was observed and was also identified in meteorological analyses. The gravity waves’ potential energy vertical profile clearly shows the GW energy lost below the inversion altitude and a large increase of gravity wave energy above the inversion in OH airglow images with waves exhibiting higher frequency. MILs are known to cause instabilities at its top part, and this is probably the reason for the enhanced gravity waves observed above.

Distributed acoustic sensing (DAS) is a highly effective method of monitoring all kinds of intrusions on railway tracks. These intrusions represent a real problem in the railway sector, as they can lead to human deaths or damage to railway tracks, and these intrusions may be human or animal. A fiber was deployed along 12 km of track in a railway test center, enabling us to acquire data day and night. A data acquisition campaign was carried out in April 2023 to capture the signatures of several scenarios (walking, digging, falling rocks, etc.) in order to train machine learning models and prevent any intrusion by detecting and classify these intrusion. The study shows the diversity of signals that fiber can acquire in the rail sector and the machine learning model performance. Signals associated with the presence of animals are also presented.

The development of renewable energies and the transmission of data around the world are two of the major challenges of our century. More than 420 submarine cables crossed the world in 2021, representing more than 1.3 million kilometres of cables in the oceans. Among these submarine cables, the dynamic cables, which are used for exporting the power of all floating offshore wind turbines, are critical components that are subjected to challenging constraints. As part of the DYNAMO (DYNAmic cable MOnitoring) project, a series of mechanical tests (traction, compression and cyclical bending) were carried out on dynamic cables fitted with optical fibres. The objective of DYNAMO is to outline the best options for monitoring dynamic cables, on the basis of current state-of-the-art on sensors and monitoring practices, elaborated in connection with a thorough review of mechanical, electrical and thermal failure modes. The data were acquired using the DxS interrogator from FOSINA consisting of both DAS (Distributed Acoustic Sensing) and DSTS (Distributed Strain and Temperature Sensing) methods. In addition to the optical fibre, three thermocouple sensors (two in the cable and one to measure the ambient temperature) were used during the experiments to compare the results. The force exerted on the cable is also known. The combination of these data showed that armor wires breaks could be detected by the fibre. These results are taken from the Time Machine Tool, developed by FOSINA, which enables the raw data to be reprocessed to obtain the most optimal acquisition parameters for detecting the desired phenomenon. In this way, data with a spatial sampling of just a few centimeters could be achieved.

The PITOP geophysical test site, operated by the Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS) in north-eastern Italy, provides a unique experimental environment for testing seismic acquisition technologies under realistic field conditions. Covering ~22,000 m², PITOP was established to support the development and validation of geophysical methods and instrumentation in both surface and borehole installations. Here, we evaluate PITOP’s potential for Distributed Acoustic Sensing (DAS) experiments, focusing on small-scale seismic measurements relevant to urban settings and engineering applications. Five boreholes with distinct purposes and instrumentation are available at the PITOP site, including a water well (PITOP1), two 400-m-deep wells associated with geosteering research (PITOP2 and PITOP3), a 150-m-deep borehole permanently equipped with optical fibre for DAS measurements (PITOP4), and a recently drilled well dedicated to geoelectrical surveys (PITOP5). The site also hosts a surface-deployed fibre-optic cable, containing both linear and helicoidal fibers, and about 20 3C seismic nodes. Finally, several seismic sources are available, which are a borehole Sparker Pulse, suitable for crosshole VSP configurations, and two surface vibratory sources, the IVI MiniVib T-2500, which can generate sweeps in the 10–550 Hz frequency range, and the ElViS VII vibrator, designed for frequencies between 20 and 220 Hz.We conducted three dedicated experiments: (i) cross-hole measurements with sources in PITOP3 at depths of 10, 50, 75, and 100 m, and DAS recording in PITOP4; (ii) a vertical seismic profiling (VSP) survey using the MiniVib source close to the well head with DAS recording in PITOP4; and (iii) recordings of the seismic wavefield generated by P- and S-wave vibratory sources using surface DAS arrays in linear and helicoidal configurations, together with co-located 3D geophones for comparison.DAS data were acquired with multiple gauge lengths and acquisition settings. The resulting datasets enable a systematic evaluation of acquisition parameters selection and highlight processing strategies required for different DAS configurations. They provide a valuable basis for assessing optimal DAS acquisition strategies for small-scale seismic applications and for defining processing workflows adapted to diverse source and receiver geometries.The present study is being carried out within the framework of the USES2 project, which receives funding from the EUROPEAN RESEARCH EXECUTIVE AGENCY (REA) under the Marie Skłodowska-Curie grant agreement No 101072599.This research has been supported by the Interdepartmental Research Center for Cultural Heritage CIBA (University of Padova) with the World Class Research Infrastructure (WCRI) SYCURI—SYnergic strategies for CUltural heritage at RIsk, funded by the University of Padova.

In the frame of the European H2020 project ARISE, a short wave infrared (SWIR) InGaAs camera has been operated at the Haute-Provence Observatory. 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 and temperature fluctuations allows us to identify and characterize gravity waves, their activity observed from the OH camera and the lidar, appear to be modified with the presence of a temperature inversion described by this one.