Diurnal cycle of air pollution in the Kathmandu Valley, Nepal: 2. Modeling results
After completing a 9-month field experiment studying air pollution and meteorology in the Kathmandu Valley, Nepal, we set up the mesoscale meteorological model MM5 to simulate the Kathmandu Valley's meteorology with a horizontal resolution of up to 1 km. After testing the model against availabl...
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
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American Geophysical Union
2014
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| Online Access: | http://hdl.handle.net/1721.1/85645 https://orcid.org/0000-0001-8616-3369 https://orcid.org/0000-0001-5925-3801 |
| _version_ | 1826208303179366400 |
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| author | Panday, Arnico K. Prinn, Ronald G. Schär, Christoph |
| author2 | Massachusetts Institute of Technology. Center for Global Change Science |
| author_facet | Massachusetts Institute of Technology. Center for Global Change Science Panday, Arnico K. Prinn, Ronald G. Schär, Christoph |
| author_sort | Panday, Arnico K. |
| collection | MIT |
| description | After completing a 9-month field experiment studying air pollution and meteorology in the Kathmandu Valley, Nepal, we set up the mesoscale meteorological model MM5 to simulate the Kathmandu Valley's meteorology with a horizontal resolution of up to 1 km. After testing the model against available data, we used it to address specific questions to understand the factors that control the observed diurnal cycle of air pollution in this urban basin in the Himalayas. We studied the dynamics of the basin's nocturnal cold air pool, its dissipation in the morning, and the subsequent growth and decay of the mixed layer over the valley. During mornings, we found behavior common to large basins, with upslope flows and basin-center subsidence removing the nocturnal cold air pool. During afternoons the circulation in the Kathmandu Valley exhibited patterns common to plateaus, with cooler denser air originating over lower regions west of Kathmandu arriving through mountain passes and spreading across the basin floor, thereby reducing the mixed layer depth. We also examined the pathways of pollutant ventilation out of the valley. The bulk of the pollution ventilation takes place during the afternoon, when strong westerly winds blow in through the western passes of the valley, and the pollutants are rapidly carried out through passes on the east and south sides of the valley. In the evening, pollutants first accumulate near the surface, but then are lifted slightly when katabatic flows converge underneath. The elevated polluted layers are mixed back down in the morning, contributing to the morning pollution peak. Later in the morning a fraction of the valley's pollutants travels up the slopes of the valley rim mountains before the westerly winds begin. |
| first_indexed | 2024-09-23T14:03:40Z |
| format | Article |
| id | mit-1721.1/85645 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T14:03:40Z |
| publishDate | 2014 |
| publisher | American Geophysical Union |
| record_format | dspace |
| spelling | mit-1721.1/856452022-09-28T18:01:25Z Diurnal cycle of air pollution in the Kathmandu Valley, Nepal: 2. Modeling results Panday, Arnico K. Prinn, Ronald G. Schär, Christoph Massachusetts Institute of Technology. Center for Global Change Science Prinn, Ronald G. Panday, Arnico K. After completing a 9-month field experiment studying air pollution and meteorology in the Kathmandu Valley, Nepal, we set up the mesoscale meteorological model MM5 to simulate the Kathmandu Valley's meteorology with a horizontal resolution of up to 1 km. After testing the model against available data, we used it to address specific questions to understand the factors that control the observed diurnal cycle of air pollution in this urban basin in the Himalayas. We studied the dynamics of the basin's nocturnal cold air pool, its dissipation in the morning, and the subsequent growth and decay of the mixed layer over the valley. During mornings, we found behavior common to large basins, with upslope flows and basin-center subsidence removing the nocturnal cold air pool. During afternoons the circulation in the Kathmandu Valley exhibited patterns common to plateaus, with cooler denser air originating over lower regions west of Kathmandu arriving through mountain passes and spreading across the basin floor, thereby reducing the mixed layer depth. We also examined the pathways of pollutant ventilation out of the valley. The bulk of the pollution ventilation takes place during the afternoon, when strong westerly winds blow in through the western passes of the valley, and the pollutants are rapidly carried out through passes on the east and south sides of the valley. In the evening, pollutants first accumulate near the surface, but then are lifted slightly when katabatic flows converge underneath. The elevated polluted layers are mixed back down in the morning, contributing to the morning pollution peak. Later in the morning a fraction of the valley's pollutants travels up the slopes of the valley rim mountains before the westerly winds begin. Massachusetts Institute of Technology (Presidential Fellowship) National Science Foundation (U.S.) (NSF grant ATM-0120468) United States. National Aeronautics and Space Administration (NASA grant NAG5-12099) United States. National Aeronautics and Space Administration (NASA grant NAG5-12669) Massachusetts Institute of Technology (TEPCO Chair account) Martin Family Society of Fellows for Sustainability Massachusetts Institute of Technology (PAOC Houghton Fund) 2014-03-14T18:19:29Z 2014-03-14T18:19:29Z 2009-11 2009-05 Article http://purl.org/eprint/type/JournalArticle 0148-0227 http://hdl.handle.net/1721.1/85645 Panday, Arnico K., Ronald G. Prinn, and Christoph Schär. “Diurnal Cycle of Air Pollution in the Kathmandu Valley, Nepal: 2. Modeling Results.” Journal of Geophysical Research 114, no. D21 (2009). https://orcid.org/0000-0001-8616-3369 https://orcid.org/0000-0001-5925-3801 en_US http://dx.doi.org/10.1029/2008jd009808 Journal of Geophysical Research Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Geophysical Union Other univ. web domain |
| spellingShingle | Panday, Arnico K. Prinn, Ronald G. Schär, Christoph Diurnal cycle of air pollution in the Kathmandu Valley, Nepal: 2. Modeling results |
| title | Diurnal cycle of air pollution in the Kathmandu Valley, Nepal: 2. Modeling results |
| title_full | Diurnal cycle of air pollution in the Kathmandu Valley, Nepal: 2. Modeling results |
| title_fullStr | Diurnal cycle of air pollution in the Kathmandu Valley, Nepal: 2. Modeling results |
| title_full_unstemmed | Diurnal cycle of air pollution in the Kathmandu Valley, Nepal: 2. Modeling results |
| title_short | Diurnal cycle of air pollution in the Kathmandu Valley, Nepal: 2. Modeling results |
| title_sort | diurnal cycle of air pollution in the kathmandu valley nepal 2 modeling results |
| url | http://hdl.handle.net/1721.1/85645 https://orcid.org/0000-0001-8616-3369 https://orcid.org/0000-0001-5925-3801 |
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