Aerosol optical properties along the northeast coast of North America during the New England Air Quality Study–Intercontinental Transport and Chemical Transformation 2004 campaign and the influence of aerosol composition

Abstract

[1] Optical and hygroscopic properties of submicrometer diameter aerosol particles were measured on board the NOAA R/V Ronald H. Brown as part of the NEAQS-ITCT field campaign. The campaign occurred along the northeast coast of North America during the summer of 2004. A scanning relative humidity (RH) nephelometry system (humidograph) measured total light scattering and backscattering coefficients (s sp and s bsp , respectively) at three wavelengths (ls) and RH = 26% and while RH was scanned between 40% and 85%. These measurements were combined with aerosol light absorption and composition measurements to describe s sp , s bsp , single scattering albedo (w), Å ngström exponent (å), and hemispheric backscatter fraction (b) at a low reference RH of 26 ± 4% and the aerosol's hygroscopic properties based on its optical response up to 85% RH. Humidogram curve structure was dominated by hygroscopic growth without hysteresis (76% frequency). Dependence of the aerosol's s sp values with changes in RH, f ssp (RH, 26), was observed to decrease with increasing mass fraction of particulate organic matter (POM, F O ). Statistical analyses indicated that increasing F O resulted in a less hygroscopic aerosol, while increasing molar equivalence ratio (ER) resulted in lower hysteresis factors based on the aerosols' optical responses at a 0.95 confidence level. w showed little RH dependence while å and b decreased with increasing RH values. Values for å(l 1 , l 2 ), b, and f ssp (82, 26) increased with increasing l values. Sensitivities of top of the atmosphere aerosol radiative forcing to changes in w, b, and s sp with RH were also estimated.

Aerosol optical properties in a rural environment near the mega-city Guangzhou, China: implications for regional air pollution, radiative forcing and remote sensing

“…Due to the strong local emissions from fires surrounding the measurement site and low wind speeds Fujitani et al (2007) (stagnation), the intensive parameters determined during the "intense smoky period" can be considered to represent the optical properties of emissions from the burning of plant farming waste. Table 2 summarizes the scattering and absorption coefficients and single scattering albedos observed in this study and in select other studies with comparable instrumentation and measurement conditions (Quinn et al, 1998;Anderson et al, 1999;Bergin et al, 2001;Man and Shih, 2001;Andreae et al, 2002;Xu et al, 2002;Anderson et al, 2003;Adam et al, 2004;Kim et al, 2004;Quinn et al, 2004;Malm et al, 2005;Fujitani et al, 2007;Li et al, 2007;Wang et al, 2007;Andreae et al, 2008;Cheng et al, 2008b). Studies not reporting the detailed measurement conditions were not included in this comparison.…”

Low hygroscopic scattering enhancement of boreal aerosol and the implications for a columnar optical closure study

“…Arctic and marine aerosols usually show the greatest values of f (RH) which decrease with increasing anthropogenic influence (e.g. f (85 %, 550 nm) ≈ 2-3.5; Titos et al, 2014a;Zieger et al, 2010;Fierz-Schmidhauser et al, 2010c;Wang et al, 2007;Carrico et al, 1998Carrico et al, , 2000Carrico et al, , 2003Gasso et al, 2000;McInnes et al, 1998). Continental aerosols (e.g.…”

Comparison of ambient aerosol extinction coefficients obtained from in-situ, MAX-DOAS and LIDAR measurements at Cabauw

“…Measured and modeled enhancement factors have been described in several previous studies, including studies on urban (Yan et al, 2009;Fitzgerald et al, 1982), continental (Sheridan et al, 2001), biomass burning (Kotchenruther and Hobbs, 1998), maritime (Fierz-Schmidhauser et al, 2010b;Wang et al, 2007;Carrico et al, 2003), free tropospheric (Fierz-Schmidhauser et al, 2010a;Nessler et al, 2005a) or Arctic aerosol .…”