An adaptable DTS-based parametric method to probe near-surface vertical temperature profiles at millimeter resolution

Abstract

We present a novel, fine-resolution temperature profiling method based on Distributed Temperature Sensing (DTS) that is adaptable, reproducible, and fully FAIR. Accurate probing of near-surface temperature gradients requires sub-centimeter resolution, particularly in environments with short vegetation such as grass, where strong insulating properties promote steep gradients. Conventional DTS systems provide spatial resolutions of approximately 25 cm along fiber optic cables that can span several kilometers. By compacting such cables into a helical coil supported by a laser-cut frame, the Fine Resolution Adaptable Distributed Temperature Sensing (FRADTS) method attains vertical resolution and accuracy at the millimeter scale. The frame design is generated by a parametric script that outputs laser-cutting files, enabling users to assemble coil structures from sheet material with identical or easily adapted geometries. We demonstrate the method in both laboratory tests and a field campaign at the CESAR atmospheric observatory in Cabauw, the Netherlands, where a prototype coil captured high-quality vertical temperature profiles within the lowest meter above the soil, including a 10 cm grass layer. A resolution of 1.3 mm was attained and verified, and the influence of environmental factors such as solar radiation and precipitation on measurement biases was mapped and quantified. Despite minor artifacts, the method proved robust and effective, providing high-quality profiles under a wide range of weather conditions. As the method is modular and parametric, it can easily be applied in other research, potentially extending its application to other fields.