Field Evaluation of Polymer Capacitive Humidity Sensors for Bowen Ratio Energy Balance Flux Measurements
Abstract
:1. Introduction
2. Theoretical Considerations
2.1. BREB Theory
2.2. Resolution of BREB Sensors Used
2.3. Error Analysis of Polymer Capacitive Humidity Instruments
- for T ≥ 20 °C
- and for T ≤ 20 °C
- and that for a CS500 for T≥ 0 °C is given by:
3. Materials and Methods
3.1. Laboratory Water Vapour Pressure Difference Measurements
3.2. Climate of the Field Site
3.3. BREB Field Measurements
3.4. Surface-Layer Scintillometer
3.5. Eddy Covariance
4. Results and Discussion
4.1. Laboratory Use of Combination Polymer Capacitive Humidity Instruments for Water Vapour Pressure Profile Difference Measurement
4.2. Field Use of Combination Polymer Capacitive Humidity Instruments for Measurement of de
4.3. Flux Comparisons
5. Summary and Conclusions
Acknowledgments
References
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Instrument | Description | Manufacturer | Specification | Approximate cost (USD, April 2010) |
---|---|---|---|---|
LI610 | Reference dewpoint generator | LI610, Li-Cor Inc., Lincoln, NE, USA | Accuracy of ±0.2 °C dewpoint | 7,600 |
Dew-10 | Dewpoint hygrometer | General Eastern Instruments, Wilmington, MA, USA | Accuracy of ±0.5 °C dewpoint, resolution of ±0.003 °C (equivalent to ±0.01 kPa) | 1,610 |
HMP45C | RH/T capacitive | Campbell Scientific Inc., Logan, UT, USA | Error magnitude of 2% RH for RH between 10 and 90%; temperature error magnitude varies with temperature—minimum 0.2 °C at 20 °C and maximum of 0.3 °C at 0 and 40 °C | 635 |
HMP35C (replaced by HMP45C) | RH/T capacitive | Campbell | Error magnitude of 2% RH for RH between 10 and 90%; temperature error magnitude varies with temperature–minimum of 0.4°C at 0 °C | |
CS500 (equivalent to HMP50) | RH/T capacitive | Campbell | Error magnitude of 3% RH for RH between 10 and 90%; temperature error magnitude varies with temperature—minimum of 0.3 °C at 0 °C and maximum of 0.62 °C at 40 °C | 425 |
Instruments not used | ||||
CS215 | RH/T capacitive | Campbell (based on model SHT75 from Sensirion AG, Zurich, Switzerland) | Similar to HMP35C | 325 |
Hygroclip SC04/SC05 | RH/T capacitive | Rotronic, Bassersdorf, Switzerland | Error magnitude of 1.5% RH for RH between 10 and 90%; temperature error magnitude of 0.3 °C | 350 |
HMP155A | RH/T capacitive | Vaisala, Campbell | δRH = ±(1+0.008RH)% and δT = ±(0.226 − 0.0028T) °C for T < 20 °C or δT = ±(0.055+0.0057T) °C for T≥20°C | 625 |
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Savage, M.J. Field Evaluation of Polymer Capacitive Humidity Sensors for Bowen Ratio Energy Balance Flux Measurements. Sensors 2010, 10, 7748-7771. https://doi.org/10.3390/s100807748
Savage MJ. Field Evaluation of Polymer Capacitive Humidity Sensors for Bowen Ratio Energy Balance Flux Measurements. Sensors. 2010; 10(8):7748-7771. https://doi.org/10.3390/s100807748
Chicago/Turabian StyleSavage, Michael J. 2010. "Field Evaluation of Polymer Capacitive Humidity Sensors for Bowen Ratio Energy Balance Flux Measurements" Sensors 10, no. 8: 7748-7771. https://doi.org/10.3390/s100807748
APA StyleSavage, M. J. (2010). Field Evaluation of Polymer Capacitive Humidity Sensors for Bowen Ratio Energy Balance Flux Measurements. Sensors, 10(8), 7748-7771. https://doi.org/10.3390/s100807748