Vertically resolved chemical characteristics and sources of submicron aerosols measured on a Tall Tower in a suburban area near Denver, Colorado in winter
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Dosyalar
Tarih
2013
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Amer Geophysical Union
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
The Nitrogen, Aerosol Composition, and Halogens on a Tall Tower study was conductedat the Boulder Atmospheric Observatory in Colorado during February–March 2011. Acompact time-of-flight aerosol mass spectrometer was installed in a moving carriage on thetower, obtaining vertical profiles of submicron nonrefractory aerosol mass concentrations(PMnr1)from0–265 m above ground level. The average PMnr1was 4.6 ± 5.7 μg/m3, withaverage contributions of nitrate, organics, sulfate, ammonium, and chloride of 35%, 26%,20%, 17%, and 1%, respectively. Positive Matrix Factorization analysis of the organic aerosol(OA) mass spectra indicated that average contributions of oxygenated organic aerosol(OOA)-I, OOA-II, and hydrocarbon-like organic aerosol (surrogates for aged and freshsecondary OA and primary OA, respectively) to OA mass were 52%, 32%, and 16%,respectively. There was considerable variability in the vertical profiles of aerosol mass loadingand composition, especially at the lowest heights. Below 40 m, the highest PMnr1concentrationswere composed of mostly nitrate (30–46%) and were associated with winds from the northeastwhere there are large agricultural facilities. When winds were southerly, PMnr1massdistributions near the surface had small, fresh OA, indicating the influence of nearby Denverurban emissions at the site. The largest contribution to OA mass at these heights was OOA-II(~43%). Between 40 and 120 m, trajectory cluster analysis indicated that during high-altitudelong-range transport events, daytime aerosol composition was dominated by sulfate, whereasduring low-altitude transport events, the contributions of sulfate, nitrate, and OA werecomparable. OOA-I contributed the most (53–68%) to OA mass at these tower heights.
Açıklama
Anahtar Kelimeler
Kaynak
Journal Of Geophysical Research-Atmospheres
WoS Q Değeri
N/A
Scopus Q Değeri
Q1
Cilt
118
Sayı
24
