Pan-Arctic aerosol number size distributions: seasonality and transport patterns

Freud, Eyal; Krejci, Radovan; Tunved, Peter; Leaitch, W. R.; Nguyen, Quynh T.; Maßling, Andreas; Skov, Henrik; Barrie, Leonard A.

doi:10.5194/acp-17-8101-2017

Cited by 134 publications

(192 citation statements)

References 79 publications

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“…The lower g values at the five Arctic sites during the summer indicate the presence of smaller particles, probably due in part to wet scavenging of larger particles and/or new particle formation. Both processes tend to be more common in the summer (e.g., Freud et al, 2017) and are consistent with the lower scattering coefficients observed in the summer. Higher g values throughout the rest of the year represent larger particles, Figure 7.…”

Section: Spatiotemporal Variability Of Aerosol Optical Properties In supporting

confidence: 81%

Seasonality of aerosol optical properties in the Arctic

et al. 2018

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Abstract. Given the sensitivity of the Arctic climate to short-lived climate forcers, long-term in situ surface measurements of aerosol parameters are useful in gaining insight into the magnitude and variability of these climate forcings. Seasonality of aerosol optical properties -including the aerosol light-scattering coefficient, absorption coefficient, single-scattering albedo, scattering Ångström exponent, and asymmetry parameter -are presented for six monitoring sites throughout the Arctic: Alert, Canada; Barrow, USA; Pallas, Finland; Summit, Greenland; Tiksi, Russia; and Zeppelin Mountain, Ny-Ålesund, Svalbard, Norway. Results show annual variability in all parameters, though the seasonality of each aerosol optical property varies from site to site. There is a large diversity in magnitude and variability of scattering coefficient at all sites, reflecting differences in aerosol source, transport, and removal at different locations throughout the Arctic. Of the Arctic sites, the highest annual mean scattering coefficient is measured at Tiksi (12.47 Mm −1 ), and the lowest annual mean scattering coefficient is measured at Summit (1.74 Mm −1 ). At most sites, aerosol absorption peaks in the winter and spring, and has a minimum throughout the Arctic in the summer, indicative of the Arctic haze phenomenon; however, nuanced variations in seasonalities suggest that this phenomenon is not identically observed in all regions of the Arctic. The highest annual mean absorption coefficient is measured at Pallas (0.48 Mm −1 ), and Summit has the lowest annual mean absorption coefficient (0.12 Mm −1 ). At the Arctic monitoring stations analyzed here, mean annual single-scattering albedo ranges from 0.909 (at Pallas) to 0.960 (at Barrow), the mean annual scattering Ångström exponent ranges from 1.04 (at Barrow) to 1.80 (at Summit), and the mean asymmetry parameter ranges from 0.57 (at Alert) to 0.75 (at Summit). Systematic variability of aerosol optical properties in the Arctic supports the notion that the sites presented here measure a variety of aerosol populations, which also experience different removal mechanisms. A robust conclusion from the seasonal cycles presented is that the Arctic cannot be treated as one common and uniform environment but rather is a region with ample spatiotemporal variability in aerosols. This notion is important in considering the design or aerosol monitoring networks in the region and is important for informing climate models to better represent short-lived aerosol climate forcers in order to yield more accurate climate predictions for the Arctic.

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Section: Spatiotemporal Variability Of Aerosol Optical Properties In supporting

confidence: 81%

Seasonality of aerosol optical properties in the Arctic

et al. 2018

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“…formation. Both processes tend to be more common in the summer (e.g., Freud et al, 2017) and are consistent with the lower scattering coefficients observed in the summer. Higher g values throughout the rest of the year represent 10 larger particles, perhaps due to long range transport.…”

supporting

confidence: 81%

Seasonality of aerosol optical properties in the Arctic

Schmeisser¹,

Backman²,

Ogren³

et al. 2018

Preprint

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Given the sensitivity of the Arctic climate to short-lived climate forcers, long-term in-situ surface measurements of aerosol parameters are useful in gaining insight into the magnitude and variability of these climate forcings. Systematic variability of aerosol optical properties in the Arctic supports the notion that the sites presented here 40 measure a variety of aerosol populations, which also experience different removal mechanisms. A robust conclusion from the seasonal cycles presented is that the Arctic cannot be treated as one common and uniform environment, but 2 rather is a region with ample spatio-temporal variability in aerosols. This notion is important in considering the design or aerosol monitoring networks in the region, and is important for informing climate models to better represent short-lived aerosol climate forcers in order to yield more accurate climate predictions for the Arctic.

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“…The OM peak is coincident with the maximum in MSA and decreasing ss-Na + , suggesting that the May peak in OM may be partly influenced by secondary processes associated with marine sources. The maximum in OM / nss-SO = 4 occurs in August, which is also when new particle formation at Alert is a maximum (Leaitch et al, 2013;Freud et al, 2017). The O / C August peak is entirely due to the summer of 2013: August O / C is 0.47 in 2012, 1.67 in 2013 and0.53 in 2014 (also, see Sect.…”

Section: Functional Groups and Oxygenationmentioning

confidence: 86%

Organic functional groups in the submicron aerosol at 82.5° N, 62.5° W from 2012 to 2014

et al. 2018

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Abstract. The first multi-year contributions from organic functional groups to the Arctic submicron aerosol are documented using 126 weekly-integrated samples collected from April 2012 to October 2014 at the Alert Observatory (82.45 • N, 62.51 • W). Results from the particle transport model FLEXPART, linear regressions among the organic and inorganic components and positive matrix factorization (PMF) enable associations of organic aerosol components with source types and regions. Lower organic mass (OM) concentrations but higher ratios of OM to non-sea-salt sulfate mass concentrations (nss-SO = 4 ) accompany smaller particles during the summer (JJA). Conversely, higher OM but lower OM / nss-SO = 4 accompany larger particles during winter-spring. OM ranges from 7 to 460 ng m −3 , and the study average is 129 ng m −3 . The monthly maximum in OM occurs during May, 1 month after the peak in nss-SO = 4 and 2 months after that of elemental carbon (EC). Winter (DJF), spring (MAM), summer and fall (SON) values of OM / nss-SO = 4 are 26, 28, 107 and 39 %, respectively, and overall about 40 % of the weekly variability in the OM is associated with nss-SO = 4 . Respective study-averaged concentrations of alkane, alcohol, acid, amine and carbonyl groups are 57, 24, 23, 15 and 11 ng m −3 , representing 42, 22, 18, 14 and 5 % of the OM, respectively. Carbonyl groups, detected mostly during spring, may have a connection with snow chemistry. The seasonally highest O / C occurs during winter (0.85) and the lowest O / C is during spring (0.51); increases in O / C are largely due to increases in alcohol groups. During winter, more than 50 % of the alcohol groups are associated with primary marine emissions, consistent with Shaw et al. (2010) and Frossard et al. (2011). A secondary marine connection, rather than a primary source, is suggested for the highest and most persistent O / C observed during the coolest and cleanest summer (2013), when alcohol and acid groups made up 63 % of the OM. A secondary marine source may be a general feature of the summer OM, but higher contributions from alkane groups to OM during the warmer summers of 2012 (53 %) and 2014 (50 %) were likely due to increased contributions from combustion sources. Evidence for significant contributions from biomass burning (BB) was present in 4 % of the weeks. During the dark months (NDJF), 29, 28 and 14 % of the nss-SO = 4 , EC and OM were associated with transport times over the gas flaring region of northern Russia and other parts of Eurasia. During spring, those percentages dropped to 11 % for each of nss-SO = 4 and EC values, respectively, and there is no association of OM.

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Pan-Arctic aerosol number size distributions: seasonality and transport patterns

Cited by 134 publications

References 79 publications

Seasonality of aerosol optical properties in the Arctic

Seasonality of aerosol optical properties in the Arctic

Seasonality of aerosol optical properties in the Arctic

Organic functional groups in the submicron aerosol at 82.5° N, 62.5° W from 2012 to 2014

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Pan-Arctic aerosol number size distributions: seasonality and transport patterns

Cited by 134 publications

References 79 publications

Seasonality of aerosol optical properties in the Arctic

Seasonality of aerosol optical properties in the Arctic

Seasonality of aerosol optical properties in the Arctic

Organic functional groups in the submicron aerosol at 82.5° N, 62.5° W from 2012 to 2014

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Product

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Organic functional groups in the submicron aerosol at 82.5° N, 62.5° W from 2012 to 2014