Quantification of temperature dependence of NOx emissions from road traffic in Norway using air quality modelling and monitoring data
Emissions of nitrogen oxides (NOx) from road traffic are dependent on a range of factors including vehicle type, speed, driving patterns and engine temperature. Recently a number of studies have indicated that ambient air temperature plays an important role in vehicle NOx emissions, mainly due to va...
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| Format: | Article |
| Language: | English |
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Elsevier
2022-01-01
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| Series: | Atmospheric Environment: X |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2590162122000144 |
| _version_ | 1819018042179321856 |
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| author | Eivind G. Wærsted Ingrid Sundvor Bruce R. Denby Qing Mu |
| author_facet | Eivind G. Wærsted Ingrid Sundvor Bruce R. Denby Qing Mu |
| author_sort | Eivind G. Wærsted |
| collection | DOAJ |
| description | Emissions of nitrogen oxides (NOx) from road traffic are dependent on a range of factors including vehicle type, speed, driving patterns and engine temperature. Recently a number of studies have indicated that ambient air temperature plays an important role in vehicle NOx emissions, mainly due to various technical challenges of diesel vehicles that occur at low ambient temperatures. This study aims to derive a correction formula to account for this temperature dependence when calculating emissions from road traffic in Norway. Measured NOx concentrations in the period 2016–2019 at 46 sites dominated by road traffic sources are compared to the NOx concentrations calculated with the chemistry-transport modelling system EMEP/uEMEP at the same sites. The model has good road traffic volume input data, but no temperature dependence in the emission factors. A clear temperature dependence in the observed-to-modelled ratio of NOx concentration is found. The ratio increases from 1.09 at high temperatures to 2.9 at low temperatures. The increase occurs gradually in the temperature range from -13 °C to +14 °C. Assuming this temperature dependence in the bias is due to the road traffic emissions, a correction formula for these emissions is derived. The correction factor is 1 at high temperatures and 3.28 at low temperatures, with a linear increase in the range from +12.4 °C to -12.9 °C. Thus, our results suggest that road traffic emissions should be 3.3 times higher at temperatures below -13 °C than at high temperatures, and 2.7 times higher at -7 °C. The temperature range and magnitude of this temperature dependence are consistent with the existing literature on emission measurement experiments performed on various models of diesel vehicles. The derived temperature dependence can be used to correct road traffic emissions. However, the parameter values in the correction are dependent on the vehicle fleet composition and are applicable only for the current Norwegian vehicle fleet. |
| first_indexed | 2024-12-21T03:13:07Z |
| format | Article |
| id | doaj.art-fda2b08a16a54c93931d36b6a7d9e92f |
| institution | Directory Open Access Journal |
| issn | 2590-1621 |
| language | English |
| last_indexed | 2024-12-21T03:13:07Z |
| publishDate | 2022-01-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Atmospheric Environment: X |
| spelling | doaj.art-fda2b08a16a54c93931d36b6a7d9e92f2022-12-21T19:17:55ZengElsevierAtmospheric Environment: X2590-16212022-01-0113100160Quantification of temperature dependence of NOx emissions from road traffic in Norway using air quality modelling and monitoring dataEivind G. Wærsted0Ingrid Sundvor1Bruce R. Denby2Qing Mu3Norwegian Meteorological Institute, Henrik Mohns plass 1, 0313, Oslo, Norway; Corresponding author.Norwegian Institute of Transport Economics, Gaustadalléen 21, 0349, Oslo, NorwayNorwegian Meteorological Institute, Henrik Mohns plass 1, 0313, Oslo, NorwayNorwegian Meteorological Institute, Henrik Mohns plass 1, 0313, Oslo, NorwayEmissions of nitrogen oxides (NOx) from road traffic are dependent on a range of factors including vehicle type, speed, driving patterns and engine temperature. Recently a number of studies have indicated that ambient air temperature plays an important role in vehicle NOx emissions, mainly due to various technical challenges of diesel vehicles that occur at low ambient temperatures. This study aims to derive a correction formula to account for this temperature dependence when calculating emissions from road traffic in Norway. Measured NOx concentrations in the period 2016–2019 at 46 sites dominated by road traffic sources are compared to the NOx concentrations calculated with the chemistry-transport modelling system EMEP/uEMEP at the same sites. The model has good road traffic volume input data, but no temperature dependence in the emission factors. A clear temperature dependence in the observed-to-modelled ratio of NOx concentration is found. The ratio increases from 1.09 at high temperatures to 2.9 at low temperatures. The increase occurs gradually in the temperature range from -13 °C to +14 °C. Assuming this temperature dependence in the bias is due to the road traffic emissions, a correction formula for these emissions is derived. The correction factor is 1 at high temperatures and 3.28 at low temperatures, with a linear increase in the range from +12.4 °C to -12.9 °C. Thus, our results suggest that road traffic emissions should be 3.3 times higher at temperatures below -13 °C than at high temperatures, and 2.7 times higher at -7 °C. The temperature range and magnitude of this temperature dependence are consistent with the existing literature on emission measurement experiments performed on various models of diesel vehicles. The derived temperature dependence can be used to correct road traffic emissions. However, the parameter values in the correction are dependent on the vehicle fleet composition and are applicable only for the current Norwegian vehicle fleet.http://www.sciencedirect.com/science/article/pii/S2590162122000144NOxLow temperature emissionsRoad traffic exhaust emissions |
| spellingShingle | Eivind G. Wærsted Ingrid Sundvor Bruce R. Denby Qing Mu Quantification of temperature dependence of NOx emissions from road traffic in Norway using air quality modelling and monitoring data Atmospheric Environment: X NOx Low temperature emissions Road traffic exhaust emissions |
| title | Quantification of temperature dependence of NOx emissions from road traffic in Norway using air quality modelling and monitoring data |
| title_full | Quantification of temperature dependence of NOx emissions from road traffic in Norway using air quality modelling and monitoring data |
| title_fullStr | Quantification of temperature dependence of NOx emissions from road traffic in Norway using air quality modelling and monitoring data |
| title_full_unstemmed | Quantification of temperature dependence of NOx emissions from road traffic in Norway using air quality modelling and monitoring data |
| title_short | Quantification of temperature dependence of NOx emissions from road traffic in Norway using air quality modelling and monitoring data |
| title_sort | quantification of temperature dependence of nox emissions from road traffic in norway using air quality modelling and monitoring data |
| topic | NOx Low temperature emissions Road traffic exhaust emissions |
| url | http://www.sciencedirect.com/science/article/pii/S2590162122000144 |
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