The thermo-time domain reflectometry (thermo-TDR) technique is valuable for monitoring in situ soil water content (θ), thermal properties, bulk density (ρ), porosity (), and air-filled porosity () in the vadose zone. However, the previous thermo-TDR sensor has several weaknesses, including limited precision of TDR waveforms due to the short probe length, small measurement volume, and thermal property estimation errors resulting from finite probe properties not accounted for by the heat pulse method. We have developed a new thermo-TDR sensor design for monitoring θ, thermal properties, ρ, , and . The new sensor has a robust heater probe (outer diameter of 2.38 mm and length of 70 mm) and a 10-mm spacing between the heater and sensing probes, which provides a sensing volume three times larger than that of the previous sensor. The identical cylindrical perfect conductors and the tangent line–second-order bounded mean oscillation theories were applied to analyze the raw data. Laboratory tests showed that θ values determined with the new sensor had a RMSE of 0.014 m m compared with 0.016 to 0.026 m m with the previous sensor. Soil thermal property estimates with the new sensor agreed well with modeled values. Soil ρ, , and derived from θ and thermal properties were consistent with those derived from gravimetric measurements. Thus, the new thermo-TDR sensor provides more accurate θ, thermal properties, ρ, , and values than the previous sensor.
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机译：热 - 时域反射测量仪（Thermo-TDR）技术对于在原位土壤含水量（θ），热性质，堆积密度（ρ），孔隙率（）和孔隙区域中的充气孔隙率（）是有价值的。然而，以前的热TDR传感器具有若干弱点，包括由于探头长度，测量量小，测量体积小，测量体积小，测量体积小，测量体积小，并且由热脉冲法而导致的热性能估计误差产生有限的精度。我们开发了一种新的热TDR传感器设计，用于监控θ，热性能，ρ和。新型传感器具有强大的加热器探针（外径为2.38毫米，长70毫米），在加热器和传感探针之间具有10mm间距，其提供比先前传感器大的3倍的传感体积。应用相同的圆柱形完美导体和切线 - 二阶界定平均振荡理论被应用于分析原始数据。实验室测试表明，用新传感器测定的θ值与先前传感器的0.014 m米的RMSE为0.014 m m。利用新传感器估计的土壤热性质估计与建模值良好。土壤ρ，衍生自θ和热性质与来自重量测量的那些一致。因此，新的热TDR传感器提供比先前传感器更精确的θ，热性能，ρ和值。
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