Linking climate and air quality over Europe: effects of meteorology on PM<sub>2.5</sub> concentrations
The effects of various meteorological parameters such as temperature, wind speed, absolute humidity, precipitation and mixing height on PM<sub>2.5</sub> concentrations over Europe were examined using a three-dimensional chemical transport model, PMCAMx-2008. Our simulations covered three...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-09-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/14/10283/2014/acp-14-10283-2014.pdf |
| Summary: | The effects of various meteorological parameters such as temperature, wind
speed, absolute humidity, precipitation and mixing height on PM<sub>2.5</sub>
concentrations over Europe were examined using a three-dimensional chemical
transport model, PMCAMx-2008. Our simulations covered three periods,
representative of different seasons (summer, winter, and fall). PM<sub>2.5</sub>
appears to be more sensitive to temperature changes compared to the other
meteorological parameters in all seasons.
<br><br>
PM<sub>2.5</sub> generally decreases as temperature increases, although the
predicted changes vary significantly in space and time, ranging from
−700 ng m<sup>−3</sup> K<sup>−1</sup> (−8% K<sup>−1</sup>) to
300 ng m<sup>−3</sup> K<sup>−1</sup> (7% K<sup>−1</sup>). The predicted decreases of
PM<sub>2.5</sub> are mainly due to evaporation of ammonium nitrate, while the
higher biogenic emissions and the accelerated gas-phase reaction rates
increase the production of organic aerosol (OA) and sulfate, having the
opposite effect on PM<sub>2.5</sub>. The predicted responses of PM<sub>2.5</sub> to
absolute humidity are also quite variable, ranging from
−130 ng m<sup>−3</sup> %<sup>−1</sup> (−1.6% %<sup>−1</sup>)
to 160 ng m<sup>−3</sup> %<sup>−1</sup> (1.6% %<sup>−1</sup>)
dominated mainly by changes in inorganic PM<sub>2.5</sub> species. An increase in
absolute humidity favors the partitioning of nitrate to the aerosol phase and
increases the average PM<sub>2.5</sub> during summer and fall. Decreases in sulfate
and sea salt levels govern the average PM<sub>2.5</sub> response to humidity during
winter. A decrease of wind speed (keeping the emissions constant) increases
all PM<sub>2.5</sub> species (on average 40 ng m<sup>−3</sup> %<sup>−1</sup>) due to
changes in dispersion and dry deposition. The wind speed effects on sea salt
emissions are significant for PM<sub>2.5</sub> concentrations over water and in
coastal areas. Increases in precipitation have a negative effect on
PM<sub>2.5</sub> (decreases up to 110 ng m<sup>−3</sup> %<sup>−1</sup>) in all periods
due to increases in wet deposition of PM<sub>2.5</sub> species and their gas
precursors. Changes in mixing height have the smallest effects (up to
35 ng m<sup>−3</sup> %<sup>−1</sup>) on PM<sub>2.5</sub> .
<br><br>
Regarding the relative importance of each of the meteorological parameters in
a changed future climate, the projected changes in precipitation are expected
to have the largest impact on PM<sub>2.5</sub> levels during all periods (changes
up to 2 μg m<sup>−3</sup> in the fall). The expected effects in future
PM<sub>2.5</sub> levels due to wind speed changes are similar in all seasons and
quite close to those resulting from future precipitation changes (up to
1.4 μg m<sup>−3</sup>). The expected increases in absolute humidity in
the future can lead to large changes in PM<sub>2.5</sub> levels (increases up to
2 μg m<sup>−3</sup>) mainly in the fall due to changes in particulate
nitrate levels. Despite the high sensitivity of PM<sub>2.5</sub> levels to
temperature, the small expected increases of temperature in the future will
lead to modest PM<sub>2.5</sub> changes and will not dominate the overall change. |
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| ISSN: | 1680-7316 1680-7324 |