Synoptic controls on summertime surface ozone in the northeastern United States

Hegarty, J. D.; Mao, Huiting; Talbot, R. W.

doi:10.1029/2006jd008170

Cited by 67 publications

(59 citation statements)

References 26 publications

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“…10. The salient features in the observed average distribution corresponding to the five map types are very similar to those in Hegarty et al (2007) where the relationship was investigated between synoptic-scale circulation patterns and surface O 3 across the northeastern US for summers [2000][2001][2002][2003][2004]. We found that FNL1 and FNL5 depict the two stages of cold front passage over the Northeast with FNL1 preceding FNL5 ( Fig.…”

Section: Association Between Circulation and O 3 Distributionsupporting

confidence: 60%

“…The synoptic-scale circulation patterns were classified by applying the correlationbased map typing algorithm of Lund (1963) to the RCMS and NCEP FNL sea level pressure (SLP) fields. This technique has been successfully applied to synoptic classification of summertime circulation patterns over the northeastern United States (Hegarty et al, 2009(Hegarty et al, , 2007Hogrefe et al, 2004). The algorithm calculates a correlation coefficient between the grids representing scalar meteorological analysis fields over a given spatial domain at different times.…”

Section: Map Typingmentioning

confidence: 99%

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A comprehensive evaluation of seasonal simulations of ozone in the northeastern US during summers of 2001–2005

et al. 2010

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Abstract. Regional air quality simulations were conducted for summers [2001][2002][2003][2004][2005] in the eastern US and subjected to extensive evaluation using various ground and airborne measurements. A brief climate evaluation focused on transport by comparing modeled dominant map types with ones from reanalysis. Reasonable agreement was found for their frequency of occurrence and distinctness of circulation patterns. The two most frequent map types from reanalysis were the Bermuda High (22%) and passage of a Canadian cold frontal over the northeastern US (20%). The model captured their frequency of occurrence at 25% and 18% respectively. The simulated five average distributions of 1-h ozone (O 3 ) daily maxima using the Community Multiscale Air Quality (CMAQ) modeling system reproduced salient features in observations. This suggests that the ability of the regional climate model to depict transport processes accurately is critical for reasonable simulations of surface O 3 . Comparison of mean bias, root mean square error, and index of agreement for CMAQ summer surface 8-h O 3 daily maxima and observations showed −0.6±14 nmol/mol, 14 nmol/mol, and 71% respectively. CMAQ performed best in moderately polluted conditions and less satisfactorily in highly polluted ones. This highlights the common problem of overestimating/underestimating lower/higher modeled O 3 levels. Diagnostic analysis suggested that significant overestimation of inland nighttime low O 3 mixing ratios may be attributed to underestimates of nitric oxide (NO) emissions at night. The absence of the second daily peak in simulations for the Appledore Island marine site possibly resulted from coarse grid resolution misrepresentation of land surface type. CompariCorrespondence to: H. Mao (hmao@gust.sr.unh.edu) son with shipboard measurements suggested that CMAQ has an inherent problem of underpredicting O 3 levels in continental outflow. Modeled O 3 vertical profiles exhibited a lack of structure indicating that key processes missing from CMAQ, such as lightning produced NO and stratospheric intrusions, are important for accurate upper tropospheric representations.

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Section: Association Between Circulation and O 3 Distributionsupporting

confidence: 60%

Section: Map Typingmentioning

confidence: 99%

A comprehensive evaluation of seasonal simulations of ozone in the northeastern US during summers of 2001–2005

et al. 2010

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“…This technique has been successfully applied to synoptic classification of summertime circulation patterns over the northeastern United States using the NCEP grids (Hegarty et al, 2007). In brief, the algorithm calculates a correlation coefficient between the grids representing scalar meteorological analysis fields over a given spatial domain at different times.…”

Section: Circulation Classificationmentioning

confidence: 99%

Synoptic influences on springtime tropospheric O<sub>3</sub> and CO over the North American export region observed by TES

2009

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Abstract.The relationship between synoptic circulation patterns over the western North Atlantic Ocean in spring (March, April, and May) and tropospheric O 3 and CO was investigated using retrievals from the Tropospheric Emission Spectrometer (TES) for 2005 and 2006. Seasonal composites of TES retrievals reprocessed to remove the artificial geographic structure added from the a priori revealed a channel of slightly elevated O 3 (>55 ppbv) and CO (>115 ppbv) at the 681 hPa retrieval level between 30 • N and 45 • N extending from North America out over the Atlantic Ocean. Ozone and CO in this region were correlated at r=0.22 with a slope value of 0.13 mol mol −1 indicative of the overall impact of photochemical chemical processes in North American continental export. Composites of TES retrievals for the six predominant circulation patterns identified as map types from sea level pressure fields of the NCEP FNL analyses showed large variability in the distribution of tropospheric O 3 . Map types MAM2 and MAM3 featuring cyclones near the US east coast produced the greatest export to the lower free troposphere with O 3 >65 ppbv and a relatively well-defined O 3 -CO correlation (slope values near 0.20 mol mol −1 ). The ensembles of HYSPLIT backward trajectories indicated that the high O 3 levels were possibly a result of pollutants lofted to the free troposphere by the warm conveyor belt (WCB) of a cyclone. An important finding was that pollutant export occurred in the main WCB branch to the east of the cyclone and in a secondary branch circling to the back of the cyclone center. Conversely, a map type featuring a large anticyclone dominating the flow over the US east coast (MAM6) restricted export with O 3 levels generally <55 ppbv and CO levels generally <110 ppbv. There was also evidence of stratospheric intrusions particularly to the north of 45 • N in the 316 hPa composites predominately Correspondence to: J. Hegarty (jhegarty@ccrc.sr.unh.edu) for MAM1 which featured a large cyclone near Newfoundland. However, the concurrence of these intrusions with pollutant export, specifically in the southwestern North Atlantic Ocean, made it difficult to delineate their respective contributions to the 681 hPa O 3 composites.

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“…Hegarty et al, 2007 showed that certain circulation patterns over northeastern United States, identified with a correlation-based synoptic categorization technique, controlled summertime surface ozone. The 500 mb geopotential height as well as the zonal and meridional wind components are used as indicators for identifying the synoptic scale circulation differences between ECHAM and ERA simulations (Figs.…”

Section: Geopotential Height and Windmentioning

confidence: 99%

Decadal regional air quality simulations over Europe in present climate: near surface ozone sensitivity to external meteorological forcing

et al. 2010

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Abstract. Regional climate-air quality decadal simulations over Europe were carried out with the RegCM3/CAMx modeling system for the time slice 1991-2000, in order to study the impact of different meteorological forcing on surface ozone. The RegCM3 regional climate model was firstly constrained by the ERA40 reanalysis dataset which is considered as an experiment with perfect meteorological boundary conditions and then it was constrained by the global circulation model ECHAM5. A number of meteorological parameters were examined including the 500 mb geopotential height, solar radiation, temperature, cloud liquid water path, planetary boundary layer height and surface wind. The different RegCM meteorological forcing resulted in changes of near surface ozone over Europe ranging between ± 4 ppb for winter and summer. The area showing the greatest sensitivity in O 3 during winter is central and southern Europe while in summer central north continental Europe. The different meteorological forcing impacts on the atmospheric circulation, which in turn affects cloudiness and solar radiation, temperature, wind patterns and the meteorology depended biogenic emissions. For comparison reasons, the impact of chemical boundary conditions on surface ozone was additionally examined with a series of sensitivity studies, indicating that surface ozone changes are comparable to those caused by the different meteorological forcing. These findings suggest that, Correspondence to: E. Katragkou (katragou@auth.gr) when it comes to regional climate-air quality simulations, the selection of external meteorological forcing can be as important as the selection of adequate chemical lateral boundary conditions.

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Synoptic controls on summertime surface ozone in the northeastern United States

Cited by 67 publications

References 26 publications

A comprehensive evaluation of seasonal simulations of ozone in the northeastern US during summers of 2001–2005

A comprehensive evaluation of seasonal simulations of ozone in the northeastern US during summers of 2001–2005

Synoptic influences on springtime tropospheric O<sub>3</sub> and CO over the North American export region observed by TES

Decadal regional air quality simulations over Europe in present climate: near surface ozone sensitivity to external meteorological forcing

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Synoptic controls on summertime surface ozone in the northeastern United States

Cited by 67 publications

References 26 publications

A comprehensive evaluation of seasonal simulations of ozone in the northeastern US during summers of 2001–2005

A comprehensive evaluation of seasonal simulations of ozone in the northeastern US during summers of 2001–2005

Synoptic influences on springtime tropospheric O&lt;sub&gt;3&lt;/sub&gt; and CO over the North American export region observed by TES

Decadal regional air quality simulations over Europe in present climate: near surface ozone sensitivity to external meteorological forcing

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Synoptic influences on springtime tropospheric O<sub>3</sub> and CO over the North American export region observed by TES