Preprints
https://doi.org/10.5194/egusphere-2023-2292
https://doi.org/10.5194/egusphere-2023-2292
27 Oct 2023
 | 27 Oct 2023

A Distributed Temperature Sensing based soil temperature profiler

Bart Schilperoort, César Jiménez Rodríguez, Bas Van de Wiel, and Miriam Coenders-Gerrits

Abstract. Storage of heat in the soil is one of the main components of the energy balance, and is essential in studying the land-atmosphere heat exchange. However, its measurement proves to be difficult, due to (vertical) soil heterogeneity and sensors easily disturbing the soil.

Improvements in precision and resolution of Distributed Temperature Sensing (DTS) equipment has resulted in widespread use in geoscientific studies. Multiple studies have shown the added value of spatially distributed measurements of soil temperature and soil heat flux. However, due to the spatial resolution of DTS measurements (~30 cm), soil temperature measurements with DTS have generally been restricted to (horizontal) spatially distributed measurements. In this paper a device is presented which allows high resolution measurements of (vertical) soil temperature profiles, by making use of a 3D printed screw-like structure.

A 50 cm tall probe is created from segments manufactured with fused filament 3D printing, and has a helical groove to guide and protect a fiber optic cable. This configuration increases the effective DTS measurement resolution, and will inhibit preferential flow along the probe. The probe was tested in the field, where the results were in agreement with the reference sensors. The high vertical resolution of the DTS-measured soil temperature allowed determination of the thermal diffusivity of the soil at a resolution of 2.5 cm, many times better than feasible with discrete probes.

Future improvements in the design could be integrated reference temperature probes, which would remove the need for DTS calibration baths. This could, in turn, support making the probes `plug and play' of the shelf instruments, without the need to splice cables or experience in DTS-setup design. The design can also support integrating an electrical conductor into the probe, and allow heat tracer experiments to derive both the heat capacity and thermal conductivity over depth at high resolution.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
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Journal article(s) based on this preprint

26 Apr 2024
A distributed-temperature-sensing-based soil temperature profiler
Bart Schilperoort, César Jiménez Rodríguez, Bas van de Wiel, and Miriam Coenders-Gerrits
Geosci. Instrum. Method. Data Syst., 13, 85–95, https://doi.org/10.5194/gi-13-85-2024,https://doi.org/10.5194/gi-13-85-2024, 2024
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

Short summary
Heat storage in the soil is difficult to measure due to vertical heterogeneity. To improve...
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