Multi-year objective analyses of warm season ground-level ozone and PM<sub>2.5</sub> over North America using real-time observations and Canadian operational air quality models
Multi-year objective analyses (OA) on a high spatiotemporal resolution for the warm season period (1 May to 31 October) for ground-level ozone and for fine particulate matter (diameter less than 2.5 microns (PM<sub>2.5</sub>)) are presented. The OA used in this study combines model outp...
| Main Authors: | , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-02-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/14/1769/2014/acp-14-1769-2014.pdf |
| _version_ | 1818310449736712192 |
|---|---|
| author | A. Robichaud R. Ménard |
| author_facet | A. Robichaud R. Ménard |
| author_sort | A. Robichaud |
| collection | DOAJ |
| description | Multi-year objective analyses (OA) on a high spatiotemporal resolution for
the warm season period (1 May to 31 October) for ground-level ozone and for
fine particulate matter (diameter less than 2.5 microns (PM<sub>2.5</sub>)) are
presented. The OA used in this study combines model outputs from the
Canadian air quality forecast suite with US and Canadian observations from
various air quality surface monitoring networks. The analyses are based on
an optimal interpolation (OI) with capabilities for adaptive error
statistics for ozone and PM<sub>2.5</sub> and an explicit bias correction scheme
for the PM<sub>2.5</sub> analyses. The estimation of error statistics has been
computed using a modified version of the Hollingsworth–Lönnberg (H–L)
method. The error statistics are "tuned" using a χ<sup>2</sup> (chi-square) diagnostic, a semi-empirical procedure that provides
significantly better verification than without tuning. Successful
cross-validation experiments were performed with an OA setup using 90%
of data observations to build the objective analyses and with the remainder
left out as an independent set of data for verification purposes.
Furthermore, comparisons with other external sources of information (global
models and PM<sub>2.5</sub> satellite surface-derived or ground-based
measurements) show reasonable agreement. The multi-year analyses obtained
provide relatively high precision with an absolute yearly averaged
systematic error of less than 0.6 ppbv (parts per billion by volume) and 0.7 μg m<sup>−3</sup> (micrograms per cubic meter) for ozone and PM<sub>2.5</sub>,
respectively, and a random error generally less than 9 ppbv for ozone and
under 12 μg m<sup>−3</sup> for PM<sub>2.5</sub>. This paper focuses on two
applications: (1) presenting long-term averages of OA and analysis increments
as a form of summer climatology; and (2) analyzing long-term (decadal) trends
and inter-annual fluctuations using OA outputs. The results show that high
percentiles of ozone and PM<sub>2.5</sub> were both following a general decreasing trend
in North America, with the eastern part of the United States showing the
most widespread decrease, likely due to more effective pollution controls.
Some locations, however, exhibited an increasing trend in the mean ozone and
PM<sub>2.5</sub>, such as the northwestern part of North America (northwest US
and Alberta). Conversely, the low percentiles are generally rising for
ozone, which may be linked to the intercontinental transport of increased
emissions from emerging countries. After removing the decadal trend, the
inter-annual fluctuations of the high percentiles are largely explained by
the temperature fluctuations for ozone and to a lesser extent by
precipitation fluctuations for PM<sub>2.5</sub>. More interesting is the economic
short-term change (as expressed by the variation of the US gross domestic
product growth rate), which explains 37% of the total variance of
inter-annual fluctuations of PM<sub>2.5</sub> and 15% in the case of ozone. |
| first_indexed | 2024-12-13T07:46:15Z |
| format | Article |
| id | doaj.art-f33cd7fa08844e4eab366d8c63dc5ca7 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-13T07:46:15Z |
| publishDate | 2014-02-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-f33cd7fa08844e4eab366d8c63dc5ca72022-12-21T23:54:49ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242014-02-011441769180010.5194/acp-14-1769-2014Multi-year objective analyses of warm season ground-level ozone and PM<sub>2.5</sub> over North America using real-time observations and Canadian operational air quality modelsA. Robichaud0R. Ménard1Atmospheric Science and Technology Directorate, Environment Canada, 2121 Trans-Canada Highway, Dorval (Québec), H9P 1J3, CanadaAtmospheric Science and Technology Directorate, Environment Canada, 2121 Trans-Canada Highway, Dorval (Québec), H9P 1J3, CanadaMulti-year objective analyses (OA) on a high spatiotemporal resolution for the warm season period (1 May to 31 October) for ground-level ozone and for fine particulate matter (diameter less than 2.5 microns (PM<sub>2.5</sub>)) are presented. The OA used in this study combines model outputs from the Canadian air quality forecast suite with US and Canadian observations from various air quality surface monitoring networks. The analyses are based on an optimal interpolation (OI) with capabilities for adaptive error statistics for ozone and PM<sub>2.5</sub> and an explicit bias correction scheme for the PM<sub>2.5</sub> analyses. The estimation of error statistics has been computed using a modified version of the Hollingsworth–Lönnberg (H–L) method. The error statistics are "tuned" using a χ<sup>2</sup> (chi-square) diagnostic, a semi-empirical procedure that provides significantly better verification than without tuning. Successful cross-validation experiments were performed with an OA setup using 90% of data observations to build the objective analyses and with the remainder left out as an independent set of data for verification purposes. Furthermore, comparisons with other external sources of information (global models and PM<sub>2.5</sub> satellite surface-derived or ground-based measurements) show reasonable agreement. The multi-year analyses obtained provide relatively high precision with an absolute yearly averaged systematic error of less than 0.6 ppbv (parts per billion by volume) and 0.7 μg m<sup>−3</sup> (micrograms per cubic meter) for ozone and PM<sub>2.5</sub>, respectively, and a random error generally less than 9 ppbv for ozone and under 12 μg m<sup>−3</sup> for PM<sub>2.5</sub>. This paper focuses on two applications: (1) presenting long-term averages of OA and analysis increments as a form of summer climatology; and (2) analyzing long-term (decadal) trends and inter-annual fluctuations using OA outputs. The results show that high percentiles of ozone and PM<sub>2.5</sub> were both following a general decreasing trend in North America, with the eastern part of the United States showing the most widespread decrease, likely due to more effective pollution controls. Some locations, however, exhibited an increasing trend in the mean ozone and PM<sub>2.5</sub>, such as the northwestern part of North America (northwest US and Alberta). Conversely, the low percentiles are generally rising for ozone, which may be linked to the intercontinental transport of increased emissions from emerging countries. After removing the decadal trend, the inter-annual fluctuations of the high percentiles are largely explained by the temperature fluctuations for ozone and to a lesser extent by precipitation fluctuations for PM<sub>2.5</sub>. More interesting is the economic short-term change (as expressed by the variation of the US gross domestic product growth rate), which explains 37% of the total variance of inter-annual fluctuations of PM<sub>2.5</sub> and 15% in the case of ozone.http://www.atmos-chem-phys.net/14/1769/2014/acp-14-1769-2014.pdf |
| spellingShingle | A. Robichaud R. Ménard Multi-year objective analyses of warm season ground-level ozone and PM<sub>2.5</sub> over North America using real-time observations and Canadian operational air quality models Atmospheric Chemistry and Physics |
| title | Multi-year objective analyses of warm season ground-level ozone and PM<sub>2.5</sub> over North America using real-time observations and Canadian operational air quality models |
| title_full | Multi-year objective analyses of warm season ground-level ozone and PM<sub>2.5</sub> over North America using real-time observations and Canadian operational air quality models |
| title_fullStr | Multi-year objective analyses of warm season ground-level ozone and PM<sub>2.5</sub> over North America using real-time observations and Canadian operational air quality models |
| title_full_unstemmed | Multi-year objective analyses of warm season ground-level ozone and PM<sub>2.5</sub> over North America using real-time observations and Canadian operational air quality models |
| title_short | Multi-year objective analyses of warm season ground-level ozone and PM<sub>2.5</sub> over North America using real-time observations and Canadian operational air quality models |
| title_sort | multi year objective analyses of warm season ground level ozone and pm sub 2 5 sub over north america using real time observations and canadian operational air quality models |
| url | http://www.atmos-chem-phys.net/14/1769/2014/acp-14-1769-2014.pdf |
| work_keys_str_mv | AT arobichaud multiyearobjectiveanalysesofwarmseasongroundlevelozoneandpmsub25subovernorthamericausingrealtimeobservationsandcanadianoperationalairqualitymodels AT rmenard multiyearobjectiveanalysesofwarmseasongroundlevelozoneandpmsub25subovernorthamericausingrealtimeobservationsandcanadianoperationalairqualitymodels |