Simulation of the Air Quality in Southern California, USA in July and October of the Year 2018
A numerical investigation of the air quality in Southern California, USA in the year 2018 is presented using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). In July, a heat wave occurred, and in October, Santa Ana conditions prevailed; these conditions and their impact...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-03-01
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| Series: | Atmosphere |
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| Online Access: | https://www.mdpi.com/2073-4433/13/4/548 |
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| author | Maximilian Herrmann Eva Gutheil |
| author_facet | Maximilian Herrmann Eva Gutheil |
| author_sort | Maximilian Herrmann |
| collection | DOAJ |
| description | A numerical investigation of the air quality in Southern California, USA in the year 2018 is presented using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). In July, a heat wave occurred, and in October, Santa Ana conditions prevailed; these conditions and their impact on air quality are the scope of the present numerical study.The high spatial resolution in the simulation includes two nested domains of 1 km and 3 km, respectively. Local climate zones land use categories are combined with the complex urban model building effect parameterization coupled with the building energy model (BEP+BEM) and the detailed MOZCART-T1 chemical reaction mechanism, which is the MOZART-T1 mechanism for trace gases with GOCART aerosols. Thus, the model is suitable to compare simulation results to in situ and satellite measurements of O<sub>3</sub>, NO<sub>2</sub>, CH<sub>4</sub>, and CO. The meteorology is captured well by the model. Comparison of simulation results with observations shows a good agreement of NO<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>2</mn></msub></semantics></math></inline-formula> and ozone, whereas CO mixing ratios are generally underestimated. This hints at missing emissions in the 2017 National Emissions Inventory (NEI) dataset. Both the heat wave and the Santa Ana winds increase the air pollution with gas-phase species in Los Angeles. In both cases, nighttime boundary layer heights are small, which causes emissions to reside near the ground. During Santa Ana winds, NOx removal on aerosols is reduced. Methane mixing ratios are modeled very well at most stations in Los Angeles, but predictions of low emissions near the University of California cause inaccuracies at that location. Modeled and observed PM2.5 agree well on low-pollution days, but high-pollution events are generally missed by the model. During the heat wave, both modeled and observed PM2.5 concentrations exceed the recommended NAAQS National Ambient Air Quality Standards value of 12.5 g/m<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mn>3</mn></msup></semantics></math></inline-formula>. The present modeling approach serves as a base for the study and prediction of special weather events and their impact on air pollution. |
| first_indexed | 2024-03-09T11:10:30Z |
| format | Article |
| id | doaj.art-dec8d66ffc22461b937717dc5971f51b |
| institution | Directory Open Access Journal |
| issn | 2073-4433 |
| language | English |
| last_indexed | 2024-03-09T11:10:30Z |
| publishDate | 2022-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Atmosphere |
| spelling | doaj.art-dec8d66ffc22461b937717dc5971f51b2023-12-01T00:46:26ZengMDPI AGAtmosphere2073-44332022-03-0113454810.3390/atmos13040548Simulation of the Air Quality in Southern California, USA in July and October of the Year 2018Maximilian Herrmann0Eva Gutheil1Interdisciplinary Center for Scientific Computing, Heidelberg University, Im Neuenheimer Feld 205, 69120 Heidelberg, GermanyInterdisciplinary Center for Scientific Computing, Heidelberg University, Im Neuenheimer Feld 205, 69120 Heidelberg, GermanyA numerical investigation of the air quality in Southern California, USA in the year 2018 is presented using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). In July, a heat wave occurred, and in October, Santa Ana conditions prevailed; these conditions and their impact on air quality are the scope of the present numerical study.The high spatial resolution in the simulation includes two nested domains of 1 km and 3 km, respectively. Local climate zones land use categories are combined with the complex urban model building effect parameterization coupled with the building energy model (BEP+BEM) and the detailed MOZCART-T1 chemical reaction mechanism, which is the MOZART-T1 mechanism for trace gases with GOCART aerosols. Thus, the model is suitable to compare simulation results to in situ and satellite measurements of O<sub>3</sub>, NO<sub>2</sub>, CH<sub>4</sub>, and CO. The meteorology is captured well by the model. Comparison of simulation results with observations shows a good agreement of NO<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>2</mn></msub></semantics></math></inline-formula> and ozone, whereas CO mixing ratios are generally underestimated. This hints at missing emissions in the 2017 National Emissions Inventory (NEI) dataset. Both the heat wave and the Santa Ana winds increase the air pollution with gas-phase species in Los Angeles. In both cases, nighttime boundary layer heights are small, which causes emissions to reside near the ground. During Santa Ana winds, NOx removal on aerosols is reduced. Methane mixing ratios are modeled very well at most stations in Los Angeles, but predictions of low emissions near the University of California cause inaccuracies at that location. Modeled and observed PM2.5 agree well on low-pollution days, but high-pollution events are generally missed by the model. During the heat wave, both modeled and observed PM2.5 concentrations exceed the recommended NAAQS National Ambient Air Quality Standards value of 12.5 g/m<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mn>3</mn></msup></semantics></math></inline-formula>. The present modeling approach serves as a base for the study and prediction of special weather events and their impact on air pollution.https://www.mdpi.com/2073-4433/13/4/548air qualityhigh resolutionLos AngelesWRF-Chemheat waveSanta Ana winds |
| spellingShingle | Maximilian Herrmann Eva Gutheil Simulation of the Air Quality in Southern California, USA in July and October of the Year 2018 Atmosphere air quality high resolution Los Angeles WRF-Chem heat wave Santa Ana winds |
| title | Simulation of the Air Quality in Southern California, USA in July and October of the Year 2018 |
| title_full | Simulation of the Air Quality in Southern California, USA in July and October of the Year 2018 |
| title_fullStr | Simulation of the Air Quality in Southern California, USA in July and October of the Year 2018 |
| title_full_unstemmed | Simulation of the Air Quality in Southern California, USA in July and October of the Year 2018 |
| title_short | Simulation of the Air Quality in Southern California, USA in July and October of the Year 2018 |
| title_sort | simulation of the air quality in southern california usa in july and october of the year 2018 |
| topic | air quality high resolution Los Angeles WRF-Chem heat wave Santa Ana winds |
| url | https://www.mdpi.com/2073-4433/13/4/548 |
| work_keys_str_mv | AT maximilianherrmann simulationoftheairqualityinsoutherncaliforniausainjulyandoctoberoftheyear2018 AT evagutheil simulationoftheairqualityinsoutherncaliforniausainjulyandoctoberoftheyear2018 |