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- Grundström, Maria, 1979, et al.
(författare)
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Influence of atmospheric circulation patterns on urban air quality during the winter
- 2015
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Ingår i: Atmospheric Pollution Research. - 1309-1042. ; 6:2, s. 278-285
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Tidskriftsartikel (refereegranskat)abstract
- Relationships between urban nitrogen dioxide (NO2) and atmospheric circulation at two spatial scales were studied for Southern Sweden. Lamb Weather Types (LWT) describe the circulation (scale: thousands of kilometers) including non–directional (cyclonic and anticyclonic) and directional types depending on the wind direction. LWTs with low wind speeds (anticyclonic, NW and N) were associated with strongly elevated [NO2], between 46–52% of the daily averages of NO2 exceeded the 60 μg m–3 air quality standard (AQS) when occurring during these LWTs. The lowest fractions of exceedances of NO2 AQS were generally observed for LWTs E, S, SW and W. A larger scale circulation (several thousands of kilometers) was represented by the North Atlantic Oscillation (NAO) affecting meteorology over middle and high latitudes in the Northern Hemisphere. While a negative NAO index (NAOI) favors stagnant high pressure weather over Northern Europe, a positive NAOI is often associated with windy conditions. High [NO2] was found to be frequent under negative NAOI. Additionally, larger fractions of exceedances of NO2 AQS were observed for the majority of LWTs occurring at negative NAOI. It’s concluded that both LWTs and NAOI had partly independent effects on the urban air quality in a North European city. These circulation indices can be useful tools for air pollution risk assessment and forecasting.
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| 2. |
- Karlsson, Per Erik, 1957, et al.
(författare)
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Increasing risk for negative ozone impacts on vegetation in northern Sweden
- 2007
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Ingår i: Environmental Pollution. ; 150, s. 96-106
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Tidskriftsartikel (refereegranskat)abstract
- Trends were found for increasing surface ozone concentrations during AprileSeptember in northern Sweden over the period 1990e2006 as well as for an earlier onset of vegetation growing season. The highest ozone concentrations in northern Sweden occurred in April and the ozone concentrations in April showed a strong increasing trend. A model simulation of ozone flux for Norway spruce indicated that the provisional ozone flux based critical level for forests in Europe is exceeded in northern Sweden. Future climate change would have counteracting effects on the stomatal conductance and needle ozone uptake, mediated on the one hand by direct effect of increasing air temperatures and on the other through increasing water vapour pressure difference between the needles and air. Thus, there is a substantial and increasing risk for negative impacts of ozone on vegetation in northern Sweden, related mainly to increasing ozone concentrations and an earlier onset of the growing season.
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