Passive distributed temperature sensing (PDTS)-based moisture content estimation in agricultural soils under different vegetative canopies

2021 ◽  
Author(s):  
Ding-feng Cao ◽  
Hong-hu Zhu ◽  
Chengchao Guo ◽  
Bing Wu ◽  
Jiachen Wang
Keyword(s):  
Moisture Content ◽  
Agricultural Soils ◽  
Temperature Sensing ◽  
Distributed Temperature Sensing

scholarly journals Uncertainties in Measuring Soil Moisture Content with Actively Heated Fiber-Optic Distributed Temperature Sensing

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3723
Author(s):  
Robert Wu ◽  
Pierrick Lamontagne-Hallé ◽  
Jeffrey M. McKenzie
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Fiber Optic ◽  
Calibration Method ◽  
Temperature Sensing ◽  
Soil Conditions ◽  
Calibration Data ◽  
Distributed Temperature Sensing ◽  
Fiber Optic Cable

Actively heated fiber-optic distributed temperature sensing (aFO-DTS) measures soil moisture content at sub-meter intervals across kilometres of fiber-optic cable. The technology has great potential for environmental monitoring but calibration at field scales with variable soil conditions is challenging. To better understand and quantify the errors associated with aFO-DTS soil moisture measurements, we use a parametric numerical modeling approach to evaluate different error factors for uniform soil. A thermo-hydrogeologic, unsaturated numerical model is used to simulate a 0.01 m by 0.01 m two-dimensional domain, including soil and a fiber-optic cable. Results from the model are compared to soil moisture values calculated using the commonly used Tcum calibration method for aFO-DTS. The model is found to have high accuracy between measured and observed saturations for static hydrologic conditions but shows discrepancies for more realistic settings with active recharge. We evaluate the performance of aFO-DTS soil moisture calculations for various scenarios, including varying recharge duration and heterogeneous soils. The aFO-DTS accuracy decreases as the variability in soil properties and intensity of recharge events increases. Further, we show that the burial of the fiber-optic cable within soil may adversely affect calculated results. The results demonstrate the need for careful selection of calibration data for this emerging method of measuring soil moisture content.

High-spatial-resolution Distributed Temperature Sensing System Based on a Mode-locked Fiber Laser

2020 ◽  
Author(s):  
Anton O. Chernutsky ◽  
Dmitriy A. Dvoretskiy ◽  
Ilya O. Orekhov ◽  
Stanislav G. Sazonkin ◽  
Yan Zh. Ososkov ◽  
...  
Keyword(s):  
Fiber Laser ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Temperature Sensing ◽  
Distributed Temperature Sensing ◽  
Sensing System

scholarly journals Thermodynamics of a fast-moving Greenlandic outlet glacier revealed by fiber-optic distributed temperature sensing

2021 ◽  
Vol 7 (20) ◽  
pp. eabe7136
Author(s):  
Robert Law ◽  
Poul Christoffersen ◽  
Bryn Hubbard ◽  
Samuel H. Doyle ◽  
Thomas R. Chudley ◽  
...  
Keyword(s):  
Fiber Optic ◽  
Basal Layer ◽  
Temperature Sensing ◽  
Distributed Temperature Sensing ◽  
Catchment Scale ◽  
Outlet Glacier ◽  
Coarse Spatial Resolution ◽  
High Vertical Resolution ◽  
Fast Motion ◽  
Strain Heating

Measurements of ice temperature provide crucial constraints on ice viscosity and the thermodynamic processes occurring within a glacier. However, such measurements are presently limited by a small number of relatively coarse-spatial-resolution borehole records, especially for ice sheets. Here, we advance our understanding of glacier thermodynamics with an exceptionally high-vertical-resolution (~0.65 m), distributed-fiber-optic temperature-sensing profile from a 1043-m borehole drilled to the base of Sermeq Kujalleq (Store Glacier), Greenland. We report substantial but isolated strain heating within interglacial-phase ice at 208 to 242 m depth together with strongly heterogeneous ice deformation in glacial-phase ice below 889 m. We also observe a high-strain interface between glacial- and interglacial-phase ice and a 73-m-thick temperate basal layer, interpreted as locally formed and important for the glacier’s fast motion. These findings demonstrate notable spatial heterogeneity, both vertically and at the catchment scale, in the conditions facilitating the fast motion of marine-terminating glaciers in Greenland.

scholarly journals A Thermal Model for Three-Core Armored Submarine Cables Based on Distributed Temperature Sensing

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3897
Author(s):  
Miguel Ángel González-Cagigal ◽  
Juan Carlos del-Pino-López ◽  
Alfonso Bachiller-Soler ◽  
Pedro Cruz-Romero ◽  
José Antonio Rosendo-Macías
Keyword(s):  
Temperature Sensing ◽  
The Finite Element Method ◽  
Current Profile ◽  
Distributed Temperature Sensing ◽  
Numerical Resolution ◽  
Electromagnetic Model ◽  
Proposed Model ◽  
Relative Errors ◽  
Dynamic Loading Conditions ◽  
Submarine Cables

This paper presents a procedure for the derivation of an equivalent thermal network-based model applied to three-core armored submarine cables. The heat losses of the different metallic cable parts are represented as a function of the corresponding temperatures and the conductor current, using a curve-fitting technique. The model was applied to two cables with different filler designs, supposed to be equipped with distributed temperature sensing (DTS) and the optical fiber location in the equivalent circuit was adjusted so that the conductor temperature could be accurately estimated using the sensor measurements. The accuracy of the proposed model was tested for both stationary and dynamic loading conditions, with the corresponding simulations carried out using a hybrid 2D-thermal/3D-electromagnetic model and the finite element method for the numerical resolution. Mean relative errors between 1 and 3% were obtained using an actual current profile. The presented procedure can be used by cable manufacturers or by utilities to properly evaluate the cable thermal situation.

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