Impacts of the Denver Cyclone on regional air quality and aerosol formation in the Colorado Front Range during FRAPPÉ 2014
Item
Title (Dublin Core)
Impacts of the Denver Cyclone on regional air quality and aerosol formation in the Colorado Front Range during FRAPPÉ 2014
Description (Dublin Core)
We present airborne measurements made during the 2014 Front Range Air Pollution and Photochemistry Experiment (FRAPPÉ) project to investigate the impacts of the Denver Cyclone on regional air quality in the greater Denver area. Data on trace gases, non-refractory submicron aerosol chemical constituents, and aerosol optical extinction (<i>β</i><sub>ext</sub>) at <i>λ</i> = 632 nm were evaluated in the presence and absence of the surface mesoscale circulation in three distinct study regions of the Front Range: In-Flow, Northern Front Range, and the Denver metropolitan area. Pronounced increases in mass concentrations of organics, nitrate, and sulfate in the Northern Front Range and the Denver metropolitan area were observed during the cyclone episodes (27–28 July) compared to the non-cyclonic days (26 July, 2–3 August). Organic aerosols dominated the mass concentrations on all evaluated days, with a 45 % increase in organics on cyclone days across all three regions, while the increase during the cyclone episode was up to ∼ 80 % over the Denver metropolitan area. In the most aged air masses (NO<sub><i>x</i></sub> / NO<sub><i>y</i></sub> < 0.5), background organic aerosols over the Denver metropolitan area increased by a factor of ∼ 2.5 due to transport from Northern Front Range. Furthermore, enhanced partitioning of nitric acid to the aerosol phase was observed during the cyclone episodes, mainly due to increased abundance of gas phase ammonia. During the non-cyclone events, <i>β</i><sub>ext</sub> displayed strong correlations (<i>r</i> = 0.71) with organic and nitrate in the Northern Front Range and only with organics (<i>r</i> = 0.70) in the Denver metropolitan area, while correlation of <i>β</i><sub>ext</sub> during the cyclone was strongest (<i>r</i> = 0.86) with nitrate over Denver. Mass extinction efficiency (MEE) values in the Denver metropolitan area were similar on cyclone and non-cyclone days despite the dominant influence of different aerosol species on <i>β</i><sub>ext</sub>. Our analysis showed that the meteorological patterns associated with the Denver Cyclone increased aerosol mass loadings in the Denver metropolitan area mainly by transporting aerosols and/or aerosol precursors from the northern regions, leading to impaired visibility and air quality deterioration.
Creator (Dublin Core)
Vu, Kennedy T.
Dingle, Justin H.
Bahreini, Roya
Reddy, Patrick J.
Apel, Eric C.
Campos, Teresa L.
DiGangi, Joshua P.
Diskin, Glenn S.
Fried, Alan
Herndon, Scott C.
Hills, Alan J.
Hornbrook, Rebecca S.
Huey, Greg
Kaser, Lisa
Montzka, Denise D.
Nowak, John B.
Pusede, Sally E.
Richter, Dirk
Roscioli, Joseph R.
Sachse, Glen W.
Shertz, Stephen
Stell, Meghan
Tanner, David
Tyndall, Geoffrey S.
Walega, James
Weibring, Peter
Weinheimer, Andrew J.
Pfister, Gabriele
Flocke, Frank
Date (Dublin Core)
2018-09-08
Type (Dublin Core)
Text
Format (Dublin Core)
application/pdf
Identifier (Dublin Core)
10.5194/acp-16-12039-2016
https://acp.copernicus.org/articles/16/12039/2016/
Source (Dublin Core)
eISSN: 1680-7324
Language (Dublin Core)
eng
