Performance validation and calibration conditions for novel dynamic baseline tracking air sensors in long-term field monitoring

<p>The rapid expansion of low-cost sensor networks for air quality monitoring necessitates rigorous calibration to ensure data accuracy. Despite numerous published field calibration studies, a universal and comprehensive assessment of factors affecting sensor calibration remains elusive, leadi...

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Main Authors: H. Mei, P. Wei, M. A. Ghadikolaei, N. K. Gali, Y. Wang, Z. Ning
Format: Article
Language:English
Published: Copernicus Publications 2025-04-01
Series:Atmospheric Measurement Techniques
Online Access:https://amt.copernicus.org/articles/18/1771/2025/amt-18-1771-2025.pdf
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author H. Mei
P. Wei
M. A. Ghadikolaei
N. K. Gali
Y. Wang
Z. Ning
author_facet H. Mei
P. Wei
M. A. Ghadikolaei
N. K. Gali
Y. Wang
Z. Ning
author_sort H. Mei
collection DOAJ
description <p>The rapid expansion of low-cost sensor networks for air quality monitoring necessitates rigorous calibration to ensure data accuracy. Despite numerous published field calibration studies, a universal and comprehensive assessment of factors affecting sensor calibration remains elusive, leading to potential discrepancies in data quality across different networks. This study deployed eight sensor-based monitors in strategically chosen locations continuously for 2 years in Hong Kong, Macau and Shanghai. These locations covered a wide range of climatic conditions: Hong Kong's subtropical climate, Macau's similar yet distinct urban environment and Shanghai's more variable climate. Each monitor employed a dynamic baseline tracking method for the gas sensors, which isolates the concentration signals from temperature and humidity effects, enhancing the sensors' accuracy and reliability. This strategic deployment ensured that the sensors' performance and calibration processes were tested across diverse atmospheric conditions. The tests, which involved evaluating the validation performance by analysing randomly selected calibration sample subsets ranging from 1–15 d, indicated that the length of the calibration period, pollutant concentration range and time-averaging period are pivotal for sensor calibration quality. We determined that a 5–7 d calibration period minimizes calibration coefficient errors, and a wider concentration range improves the validation <span class="inline-formula"><i>R</i><sup>2</sup></span> values for all sensors, suggesting the necessity of setting specific concentration range thresholds. A time-averaging period of at least 5 min for data with 1 min resolution was recommended to enable optimal calibration in field operation. This study emphasizes the need for a comprehensive calibration assessment and the importance of considering environmental variability in the sensor calibration condition. These findings offer methodological guidance for the calibration of other sensor types, providing a reference for future research in the field of sensor calibration.</p>
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spelling doaj-art-e2bddc1c25324dff95869059deb708f82025-08-20T02:12:38ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482025-04-01181771178510.5194/amt-18-1771-2025Performance validation and calibration conditions for novel dynamic baseline tracking air sensors in long-term field monitoringH. Mei0P. Wei1M. A. Ghadikolaei2N. K. Gali3Y. Wang4Z. Ning5Division of Environment and Sustainability, The Hong Kong University of Science and Technology, Hong Kong SAR, ChinaCollege of Geography and Environment, Shandong Normal University, Jinan, ChinaDivision of Environment and Sustainability, The Hong Kong University of Science and Technology, Hong Kong SAR, ChinaDivision of Environment and Sustainability, The Hong Kong University of Science and Technology, Hong Kong SAR, ChinaDivision of Environment and Sustainability, The Hong Kong University of Science and Technology, Hong Kong SAR, ChinaDivision of Environment and Sustainability, The Hong Kong University of Science and Technology, Hong Kong SAR, China<p>The rapid expansion of low-cost sensor networks for air quality monitoring necessitates rigorous calibration to ensure data accuracy. Despite numerous published field calibration studies, a universal and comprehensive assessment of factors affecting sensor calibration remains elusive, leading to potential discrepancies in data quality across different networks. This study deployed eight sensor-based monitors in strategically chosen locations continuously for 2 years in Hong Kong, Macau and Shanghai. These locations covered a wide range of climatic conditions: Hong Kong's subtropical climate, Macau's similar yet distinct urban environment and Shanghai's more variable climate. Each monitor employed a dynamic baseline tracking method for the gas sensors, which isolates the concentration signals from temperature and humidity effects, enhancing the sensors' accuracy and reliability. This strategic deployment ensured that the sensors' performance and calibration processes were tested across diverse atmospheric conditions. The tests, which involved evaluating the validation performance by analysing randomly selected calibration sample subsets ranging from 1–15 d, indicated that the length of the calibration period, pollutant concentration range and time-averaging period are pivotal for sensor calibration quality. We determined that a 5–7 d calibration period minimizes calibration coefficient errors, and a wider concentration range improves the validation <span class="inline-formula"><i>R</i><sup>2</sup></span> values for all sensors, suggesting the necessity of setting specific concentration range thresholds. A time-averaging period of at least 5 min for data with 1 min resolution was recommended to enable optimal calibration in field operation. This study emphasizes the need for a comprehensive calibration assessment and the importance of considering environmental variability in the sensor calibration condition. These findings offer methodological guidance for the calibration of other sensor types, providing a reference for future research in the field of sensor calibration.</p>https://amt.copernicus.org/articles/18/1771/2025/amt-18-1771-2025.pdf
spellingShingle H. Mei
P. Wei
M. A. Ghadikolaei
N. K. Gali
Y. Wang
Z. Ning
Performance validation and calibration conditions for novel dynamic baseline tracking air sensors in long-term field monitoring
Atmospheric Measurement Techniques
title Performance validation and calibration conditions for novel dynamic baseline tracking air sensors in long-term field monitoring
title_full Performance validation and calibration conditions for novel dynamic baseline tracking air sensors in long-term field monitoring
title_fullStr Performance validation and calibration conditions for novel dynamic baseline tracking air sensors in long-term field monitoring
title_full_unstemmed Performance validation and calibration conditions for novel dynamic baseline tracking air sensors in long-term field monitoring
title_short Performance validation and calibration conditions for novel dynamic baseline tracking air sensors in long-term field monitoring
title_sort performance validation and calibration conditions for novel dynamic baseline tracking air sensors in long term field monitoring
url https://amt.copernicus.org/articles/18/1771/2025/amt-18-1771-2025.pdf
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AT ywang performancevalidationandcalibrationconditionsfornoveldynamicbaselinetrackingairsensorsinlongtermfieldmonitoring
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