| 王黎明,周旭辉,雷永恒.温度对 FDR 土壤水分传感器测量影响[J].电子测量与仪器学报,2021,35(4):46-54 |
| 温度对 FDR 土壤水分传感器测量影响 |
| Temperature effect on FDR soil moisture sensor measurement |
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| DOI： |
| 中文关键词: FDR 土壤水分传感器 标定温度 测量影响 |
| 英文关键词:FDR soil moisture sensor calibration temperature measurement effect |
| 基金项目:湖南省气象局重点科研(XQKJ17A003)、湖南省气象局科技创新项目(201812)资助 |
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| 中文摘要: |
| 为准确研究标定温度对 FDR(frequency domain refletrometry)电容式土壤水分传感器测量影响,提高组网观测数据之间
的一致性。 针对电容式土壤水分传感器的测量范围,首先设计了基准频率温度影响实验方案,通过实验得到了传感器在空气和
水介质中频率随温度的变化关系以及实验环境下空气温度和水温度之间的关系,并以水温为独立变量,导出了归一化频率温度
关系,水温升高 1 ℃ ,频率平均增加 6. 618 5 Hz;气温度升高 1 ℃ ,频率平均减少 4. 860 5 Hz;归一化频率与标定温度关系函数存
在一个临界点,土壤湿度大于临界点时归一化频率随温度升高而增加,湿度越高归一化频率增加越大,低于临界点时归一化频
率随温度升高而减小,湿度越低归一化频率减小越大。 再用两种典型质地的原状土壤样本对传感器进行校准,利用传感器校准
曲线导出了原状土壤体积含水量随标定温度变化关系,结果表明,标定温度对原状土壤校准后的体积含水量测量影响最高
0. 12% cm
3·cm
-3·℃
-1
,实验温度范围内(0~ 50 ℃ )体积含水量测量误差最高为 5. 93%(cm
3·cm
-3
)。 |
| 英文摘要: |
| In order to accurately study the influence of calibration temperature on frequency domain reflectometry (FDR) capacitive soil
moisture sensor measurement, to improve the consistency of the data of network measurement sensors deployed in different sites.
According to the measurement range of capacitive soil moisture sensor, the temperature effect of reference frequency experiment scheme
is proposed. The relationship between the frequency of the sensor and temperature in air and water media is obtained by experiment, and
the relationship between air temperature and water temperature is also obtained through the experiment. Furthermore, the relationship
between normalized frequency and water media temperature is derived with water temperature as independent variable. According to the
air frequency temperature fitting equation, the number of frequency reduction 4. 860 5 Hz on average when the air media temperature
rises 1 ℃ ; and according to the water frequency temperature fitting equation, the number of frequency increases 6. 615 5 Hz on average
when the water media temperature increase 1 ℃ . There is an inflection point between the normalized frequency and the water calibration
temperature function, When the soil moisture is higher than the inflection point, the normalized frequency increases with the increase of
temperature, The higher the soil moisture is, the higher the normalized frequency. When the soil moisture is lower than the inflection
point, the normalized frequency decreases with the increase of temperature, the lower the soil moisture is, the higher the normalized
frequency reduction rate. Secondly, calibrate the soil moisture sensor with two typical texture undisturbed soil sample. Based on the
calibration curve of the sensor, the relationship between the volumetric water content of undisturbed soil and he calibration temperature is
derived. The result show that the maximum influence error of calibration temperature on the measurement of volumetric moisture content
of undisturbed soil is 0. 12% cm
3·cm
-3·℃
-1
, The measurement error of volume content in the temperature range of experimental is
5. 93%(cm
3·cm
-3
). |
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