Analysis of Surface Level PM2.5 Measured by Low-Cost Sensor and Satellite-Based Column Aerosol Optical Depth (AOD) over Kathmandu
Abstract A low-cost PurpleAir PA-II sensor was installed, in 2020 at the Institute of Engineering (IOE) Pulchowk Campus, TU located in Kathmandu valley, Nepal, to measure particulate matter with an aerodynamic diameter equal to or smaller than 2.5 µm (PM2.5). The observation shows that hourly averag...
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| Format: | Article |
| Language: | English |
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Springer
2022-12-01
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| Series: | Aerosol and Air Quality Research |
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| Online Access: | https://doi.org/10.4209/aaqr.220311 |
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| author | Jeevan Regmi Khem N. Poudyal Amod Pokhrel Nabin Malakar Madhu Gyawali Lekhendra Tripathee Mukesh Rai Srikanthan Ramachandran Katrina Wilson Rudra Aryal |
| author_facet | Jeevan Regmi Khem N. Poudyal Amod Pokhrel Nabin Malakar Madhu Gyawali Lekhendra Tripathee Mukesh Rai Srikanthan Ramachandran Katrina Wilson Rudra Aryal |
| author_sort | Jeevan Regmi |
| collection | DOAJ |
| description | Abstract A low-cost PurpleAir PA-II sensor was installed, in 2020 at the Institute of Engineering (IOE) Pulchowk Campus, TU located in Kathmandu valley, Nepal, to measure particulate matter with an aerodynamic diameter equal to or smaller than 2.5 µm (PM2.5). The observation shows that hourly averaged PM2.5 fluctuates bimodally in four seasons (Winter: December, January, and February; Spring: March–May; Summer: June–September; and Autumn: October–November), with the highest levels occurring during morning and evening rush hours. PurpleAir records PM2.5 with a maximum average of 101 ± 26.31 µg m−3, in winter, 55.58 ± 11.42 µg m−3, in spring, 45.46 ± 12.16 µg m−3, in autumn, and a minimum of 22.78 ± 3.23 µg m−3, in the summer. Due to rain and diffusion in the vertical atmosphere, PM2.5 levels are lowest during the summer. The ± number for each season represents the standard deviation from the hourly average. AOD550nm data collected by MODIS (Moderate Resolution Imaging Spectroradiometer) onboard two NASA satellites, Terra and Aqua, are compared with simultaneously observed PM2.5. With humidity correction factor f(RH), R2 increases from 0.413 to 0.608 (in winter), 0.426 to 0.508 (in spring), and 0.083 to 0.293 (in autumn). The summer AOD data and PM2.5 are not compared due to a lack of AOD observations. By comparing the column-integrated aerosol data with the surface-level aerosol concentration, this study illustrates the relevance of atmospheric parameters while investigating the reliability of PurpleAir measurements. A cluster analysis of five-day back trajectories of air masses arriving at different altitudes in different seasons indicates that long-range transport of air pollution contributes to MODIS’s column integrated AOD by adding aerosol population. |
| format | Article |
| id | doaj-art-b6bc53b6fe1346d78e13be2b57b54abd |
| institution | Kabale University |
| issn | 1680-8584 2071-1409 |
| language | English |
| publishDate | 2022-12-01 |
| publisher | Springer |
| record_format | Article |
| series | Aerosol and Air Quality Research |
| spelling | doaj-art-b6bc53b6fe1346d78e13be2b57b54abd2025-02-09T12:22:38ZengSpringerAerosol and Air Quality Research1680-85842071-14092022-12-0123111510.4209/aaqr.220311Analysis of Surface Level PM2.5 Measured by Low-Cost Sensor and Satellite-Based Column Aerosol Optical Depth (AOD) over KathmanduJeevan Regmi0Khem N. Poudyal1Amod Pokhrel2Nabin Malakar3Madhu Gyawali4Lekhendra Tripathee5Mukesh Rai6Srikanthan Ramachandran7Katrina Wilson8Rudra Aryal9Prithvi Narayan Campus, Tribhuvan University (TU)Department of Applied Sciences, IOE Pulchowk Campus, Tribhuvan UniversityUniversity of California BerkeleyWorcester State UniversityDepartment of Physics, San Jacinto College, South CampusState Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of SciencesState Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of SciencesPhysical Research LaboratoryFranklin Pierce UniversityFranklin Pierce UniversityAbstract A low-cost PurpleAir PA-II sensor was installed, in 2020 at the Institute of Engineering (IOE) Pulchowk Campus, TU located in Kathmandu valley, Nepal, to measure particulate matter with an aerodynamic diameter equal to or smaller than 2.5 µm (PM2.5). The observation shows that hourly averaged PM2.5 fluctuates bimodally in four seasons (Winter: December, January, and February; Spring: March–May; Summer: June–September; and Autumn: October–November), with the highest levels occurring during morning and evening rush hours. PurpleAir records PM2.5 with a maximum average of 101 ± 26.31 µg m−3, in winter, 55.58 ± 11.42 µg m−3, in spring, 45.46 ± 12.16 µg m−3, in autumn, and a minimum of 22.78 ± 3.23 µg m−3, in the summer. Due to rain and diffusion in the vertical atmosphere, PM2.5 levels are lowest during the summer. The ± number for each season represents the standard deviation from the hourly average. AOD550nm data collected by MODIS (Moderate Resolution Imaging Spectroradiometer) onboard two NASA satellites, Terra and Aqua, are compared with simultaneously observed PM2.5. With humidity correction factor f(RH), R2 increases from 0.413 to 0.608 (in winter), 0.426 to 0.508 (in spring), and 0.083 to 0.293 (in autumn). The summer AOD data and PM2.5 are not compared due to a lack of AOD observations. By comparing the column-integrated aerosol data with the surface-level aerosol concentration, this study illustrates the relevance of atmospheric parameters while investigating the reliability of PurpleAir measurements. A cluster analysis of five-day back trajectories of air masses arriving at different altitudes in different seasons indicates that long-range transport of air pollution contributes to MODIS’s column integrated AOD by adding aerosol population.https://doi.org/10.4209/aaqr.220311Aerosol optical depthMODISPM2.5PurpleAirTransboundary aerosols |
| spellingShingle | Jeevan Regmi Khem N. Poudyal Amod Pokhrel Nabin Malakar Madhu Gyawali Lekhendra Tripathee Mukesh Rai Srikanthan Ramachandran Katrina Wilson Rudra Aryal Analysis of Surface Level PM2.5 Measured by Low-Cost Sensor and Satellite-Based Column Aerosol Optical Depth (AOD) over Kathmandu Aerosol and Air Quality Research Aerosol optical depth MODIS PM2.5 PurpleAir Transboundary aerosols |
| title | Analysis of Surface Level PM2.5 Measured by Low-Cost Sensor and Satellite-Based Column Aerosol Optical Depth (AOD) over Kathmandu |
| title_full | Analysis of Surface Level PM2.5 Measured by Low-Cost Sensor and Satellite-Based Column Aerosol Optical Depth (AOD) over Kathmandu |
| title_fullStr | Analysis of Surface Level PM2.5 Measured by Low-Cost Sensor and Satellite-Based Column Aerosol Optical Depth (AOD) over Kathmandu |
| title_full_unstemmed | Analysis of Surface Level PM2.5 Measured by Low-Cost Sensor and Satellite-Based Column Aerosol Optical Depth (AOD) over Kathmandu |
| title_short | Analysis of Surface Level PM2.5 Measured by Low-Cost Sensor and Satellite-Based Column Aerosol Optical Depth (AOD) over Kathmandu |
| title_sort | analysis of surface level pm2 5 measured by low cost sensor and satellite based column aerosol optical depth aod over kathmandu |
| topic | Aerosol optical depth MODIS PM2.5 PurpleAir Transboundary aerosols |
| url | https://doi.org/10.4209/aaqr.220311 |
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