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.

中文翻译：

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基于分布式温度传感的土壤温度剖面仪

摘要。土壤中的热量储存是能量平衡的主要组成部分之一，对于研究陆地-大气热交换至关重要。
然而，由于（垂直）土壤异质性和传感器容易干扰土壤，其测量被证明是困难的。分布式温度传感 (DTS) 设备精度和分辨率的提高已在地球科学研究中得到广泛应用。
多项研究表明土壤温度和土壤热通量的空间分布测量具有附加值。然而，由于 DTS 测量的空间分辨率（~30 cm），DTS 土壤温度测量通常仅限于（水平）空间分布测量。本文提出了一种装置，通过利用 3D 打印的螺旋状结构，可以对（垂直）土壤温度剖面进行高分辨率测量。50 厘米高的探针由熔丝 3D 打印制造的片段制成，并具有螺旋槽以引导和保护光缆。这种配置提高了有效的 DTS 测量分辨率，并将抑制沿探头的优先流动。该探头在现场进行了测试，结果与参考传感器一致。DTS 测量的土壤温度的高垂直分辨率允许以 2.5 厘米的分辨率测定土壤的热扩散率，比离散探头的可行方法好很多倍。未来设计的改进可能是集成参考温度探头，这将消除对 DTS 校准槽的需要。
反过来，这可以支持使架式仪器的探头“即插即用”，无需拼接电缆或具有 DTS 设置设计经验。该设计还可以支持将电导体集成到探头中，并允许伴热器实验以高分辨率导出随深度变化的热容和热导率。