34 research outputs found
Seismic noise parameters as indicators of reversible modifications in slope stability: a review
Continuous ambient seismic monitoring of potentially unstable sites is increasingly attracting
the attention of researchers for precursor recognition and early warning purposes.
Twelve cases of long-term continuous noise monitoring have been reported in the literature
between 2012 and 2020. Only in a few cases rupture was achieved and irreversible
drops in resonance frequency values or shear wave velocity extracted from noise recordings
were documented. On the other hand, all monitored sites showed clear reversible fluctuations
of the seismic parameters on a daily and seasonal scale due to changes in external
weather conditions (air temperature and precipitation). A quantitative comparison of these
reversible modifications is used to gain insight into the mechanisms driving the site seismic
response. Six possible mechanisms were identified, including three temperature-driven
mechanisms (temperature control on fracture opening/closing, superficial stress conditions
and bulk rigidity), one precipitation-driven mechanism (water infiltration effect) and two
mechanisms sensitive to both temperature and precipitation (ice formation and clay behavior).
The reversible variations in seismic parameters under the meteorological constraints
are synthesized and compared to the irreversible changes observed prior to failure in different
geological conditions
Estimating Permafrost Distribution Using Co‐Located Temperature and Electrical Resistivity Measurements
Assessing the lateral and vertical extent of permafrost is critical to understanding the fate of Arctic ecosystems under climate change. Yet, direct measurements of permafrost distribution and temperature are often limited to a small number of borehole locations. Here, we assess the use of co-located shallow temperature and electrical resistivity tomography (ERT) measurements to estimate at high-resolution the distribution of permafrost in three watersheds underlain by discontinuous permafrost. Synthetic modeling shows that co-located temperature and ERT measurements allow for supervised classification schemes that provide 60% higher accuracy compared to unsupervised methods. Linking resistivity and size of the identified permafrost bodies to surface observations, we show that tall vegetation (>0.5 m) and gentle slopes (<15°) are related to warmer and smaller permafrost bodies, and a more frequent occurrence of taliks
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A distributed temperature profiling system for vertically and laterally dense acquisition of soil and snow temperature
Abstract. Measuring soil and snow temperature with high vertical
and lateral resolution is critical for advancing the predictive
understanding of thermal and hydro-biogeochemical processes that govern the
behavior of environmental systems. Vertically resolved soil temperature
measurements enable the estimation of soil thermal regimes, frozen-/thawed-layer thickness, thermal parameters, and heat and/or water fluxes.
Similarly, they can be used to capture the snow depth and the snowpack
thermal parameters and fluxes. However, these measurements are challenging
to acquire using conventional approaches due to their total cost, their
limited vertical resolution, and their large installation footprint. This
study presents the development and validation of a novel distributed
temperature profiling (DTP) system that addresses these challenges. The
system leverages digital temperature sensors to provide unprecedented,
finely resolved depth profiles of temperature measurements with flexibility
in system geometry and vertical resolution. The integrated miniaturized
logger enables automated data acquisition, management, and wireless
transfer. A novel calibration approach adapted to the DTP system confirms
the factory-assured sensor accuracy of ±0.1 ∘C and
enables improving it to ±0.015 ∘C. Numerical
experiments indicate that, under normal environmental conditions, an
additional error of 0.01 % in amplitude and 70 s time delay in
amplitude for a diurnal period can be expected, owing to the DTP housing. We demonstrate the DTP systems capability at two field sites, one focused on understanding how snow dynamics influence mountainous water resources and the other focused on understanding how soil properties influence carbon
cycling. Results indicate that the DTP system reliably captures the dynamics in snow depth and soil freezing and thawing depth, enabling advances in
understanding the intensity and timing in surface processes and their impact on subsurface thermohydrological regimes. Overall, the DTP system fulfills the needs for data accuracy, minimal power consumption, and low total cost,
enabling advances in the multiscale understanding of various cryospheric and hydro-biogeochemical processes
The C<sup>2</sup>Omodo Concept: A Tandem of New Generation High Resolution All-Sky Atmospheric Sounders in the Frame of the AOS Mission
International audienceConvective systems are responsible for energy transfers between the lower and upper atmospheric layers and play a fundamental role in the water cycle, weather and climate evolution. With a tandem of high resolution and wide swath all-sky atmospheric sounders, the C 2 OMODO concept allows the estimation of vertical dynamics within deep convective systems