Mixing Layer Height Retrievals From MiniMPL Measurements in the Chiang Mai Valley: Implications for Particulate Matter Pollution
Urbanized mountain valleys are usually prone to episodes of high concentrations of air pollutants due to the strong interplay between mountain meteorology and synoptic weather conditions. The mountain valley of Chiang Mai is engulfed by air pollutants with particulate matter (PM) concentration remai...
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Frontiers Media S.A.
2019-11-01
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| Series: | Frontiers in Earth Science |
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| Online Access: | https://www.frontiersin.org/article/10.3389/feart.2019.00308/full |
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| author | Raman Solanki Ronald Macatangay Ronald Macatangay Vichawan Sakulsupich Thiranan Sonkaew Parth Sarathi Mahapatra |
| author_facet | Raman Solanki Ronald Macatangay Ronald Macatangay Vichawan Sakulsupich Thiranan Sonkaew Parth Sarathi Mahapatra |
| author_sort | Raman Solanki |
| collection | DOAJ |
| description | Urbanized mountain valleys are usually prone to episodes of high concentrations of air pollutants due to the strong interplay between mountain meteorology and synoptic weather conditions. The mountain valley of Chiang Mai is engulfed by air pollutants with particulate matter (PM) concentration remaining above 50 μg m–3 (PM2.5, 24-h average) during approximately 13% days every year (mostly during February to April). This study presents the first time continuous measurements of mini–micro pulse LiDAR (MiniMPL) installed on the valley floor of Chiang Mai, providing vertical backscatter profile of aerosols and clouds from April 2017 onward. This paper analyzes unique dataset of mixing layer (ML) height measurements made during April 2017 to June 2018 with a temporal resolution of 15 min. The ML heights derived from the backscatter profile measurements are analyzed to understand the annual, monthly, and diurnal variations. The ML height depicts distinct diurnal variations for all months of the year, evolving up to <3.0 km during April to September. From October onward the ML evolution is gradually inhibited, reducing to <2.0 km during October to December and <1.5 km during January to March. The variations in the concentration of PM were found to be partly modulated by the ML variations (Pearson coefficient ≈ –0.50) during dry season (February, March, and April), possibly triggering the aerosol-boundary layer feedback mechanism for high concentrations (100 μg m–3) of PM and low ventilation in the valley. The inhibition of ML evolution due to feedback mechanism further escalates the high concentrations of PM, resulting in severe haze conditions on many days during the dry season. |
| first_indexed | 2024-12-21T09:04:18Z |
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| id | doaj.art-cb332586c8f64009b13d1fefb66a4d41 |
| institution | Directory Open Access Journal |
| issn | 2296-6463 |
| language | English |
| last_indexed | 2024-12-21T09:04:18Z |
| publishDate | 2019-11-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Earth Science |
| spelling | doaj.art-cb332586c8f64009b13d1fefb66a4d412022-12-21T19:09:23ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632019-11-01710.3389/feart.2019.00308493919Mixing Layer Height Retrievals From MiniMPL Measurements in the Chiang Mai Valley: Implications for Particulate Matter PollutionRaman Solanki0Ronald Macatangay1Ronald Macatangay2Vichawan Sakulsupich3Thiranan Sonkaew4Parth Sarathi Mahapatra5Atmospheric Research Unit, National Astronomical Research Institute of Thailand, Chiang Mai, ThailandAtmospheric Research Unit, National Astronomical Research Institute of Thailand, Chiang Mai, ThailandInstitute of Environmental Science and Meteorology, University of the Philippines Diliman, Quezon City, PhilippinesAtmospheric Research Unit, National Astronomical Research Institute of Thailand, Chiang Mai, ThailandScience Faculty, Lampang Rajabhat University, Lampang, ThailandInternational Centre for Integrated Mountain Development (ICIMOD), Kathmandu, NepalUrbanized mountain valleys are usually prone to episodes of high concentrations of air pollutants due to the strong interplay between mountain meteorology and synoptic weather conditions. The mountain valley of Chiang Mai is engulfed by air pollutants with particulate matter (PM) concentration remaining above 50 μg m–3 (PM2.5, 24-h average) during approximately 13% days every year (mostly during February to April). This study presents the first time continuous measurements of mini–micro pulse LiDAR (MiniMPL) installed on the valley floor of Chiang Mai, providing vertical backscatter profile of aerosols and clouds from April 2017 onward. This paper analyzes unique dataset of mixing layer (ML) height measurements made during April 2017 to June 2018 with a temporal resolution of 15 min. The ML heights derived from the backscatter profile measurements are analyzed to understand the annual, monthly, and diurnal variations. The ML height depicts distinct diurnal variations for all months of the year, evolving up to <3.0 km during April to September. From October onward the ML evolution is gradually inhibited, reducing to <2.0 km during October to December and <1.5 km during January to March. The variations in the concentration of PM were found to be partly modulated by the ML variations (Pearson coefficient ≈ –0.50) during dry season (February, March, and April), possibly triggering the aerosol-boundary layer feedback mechanism for high concentrations (100 μg m–3) of PM and low ventilation in the valley. The inhibition of ML evolution due to feedback mechanism further escalates the high concentrations of PM, resulting in severe haze conditions on many days during the dry season.https://www.frontiersin.org/article/10.3389/feart.2019.00308/fullaerosolsMiniMPLmixing layer heightaerosol layer heightparticulate mattermountain valley |
| spellingShingle | Raman Solanki Ronald Macatangay Ronald Macatangay Vichawan Sakulsupich Thiranan Sonkaew Parth Sarathi Mahapatra Mixing Layer Height Retrievals From MiniMPL Measurements in the Chiang Mai Valley: Implications for Particulate Matter Pollution Frontiers in Earth Science aerosols MiniMPL mixing layer height aerosol layer height particulate matter mountain valley |
| title | Mixing Layer Height Retrievals From MiniMPL Measurements in the Chiang Mai Valley: Implications for Particulate Matter Pollution |
| title_full | Mixing Layer Height Retrievals From MiniMPL Measurements in the Chiang Mai Valley: Implications for Particulate Matter Pollution |
| title_fullStr | Mixing Layer Height Retrievals From MiniMPL Measurements in the Chiang Mai Valley: Implications for Particulate Matter Pollution |
| title_full_unstemmed | Mixing Layer Height Retrievals From MiniMPL Measurements in the Chiang Mai Valley: Implications for Particulate Matter Pollution |
| title_short | Mixing Layer Height Retrievals From MiniMPL Measurements in the Chiang Mai Valley: Implications for Particulate Matter Pollution |
| title_sort | mixing layer height retrievals from minimpl measurements in the chiang mai valley implications for particulate matter pollution |
| topic | aerosols MiniMPL mixing layer height aerosol layer height particulate matter mountain valley |
| url | https://www.frontiersin.org/article/10.3389/feart.2019.00308/full |
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