Frost flower aerosol effects on Arctic wintertime longwave cloud radiative forcing

Xu, Li; Russell, Lynn M.; Somerville, Richard C. J.; Quinn, Patricia K.

doi:10.1002/2013jd020554

Cited by 28 publications

(57 citation statements)

References 63 publications

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“…The January peak coincided with a local blizzard, which may indicate local marine sources such as open water, blowing saline snow, or frost flowers. A strong correlation between high winds and salt emissions from fresh sea ice frost flowers has been suggested by others (e.g., Xu et al, 2013). However, Factor 1 also showed a moderate correlation with collection period length (Pearson's correlation coefficient of 0.47) and the noted January peak was one of the longest collection periods in the campaign.…”

Section: Factor 1: Sea Saltsupporting

confidence: 68%

Temporally delineated sources of major chemical species in high Arctic snow

et al. 2018

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Abstract. Long-range transport of aerosol from lower latitudes to the high Arctic may be a significant contributor to climate forcing in the Arctic. To identify the sources of key contaminants entering the Canadian High Arctic an intensive campaign of snow sampling was completed at Alert, Nunavut, from September 2014 to June 2015. Fresh snow samples collected every few days were analyzed for black carbon, major ions, and metals, and this rich data set provided an opportunity for a temporally refined source apportionment of snow composition via positive matrix factorization (PMF) in conjunction with FLEXPART (FLEXible PARTicle dispersion model) potential emission sensitivity analysis. Seven source factors were identified: sea salt, crustal metals, black carbon, carboxylic acids, nitrate, noncrustal metals, and sulfate. The sea salt and crustal factors showed good agreement with expected composition and primarily northern sources. High loadings of V and Se onto Factor 2, crustal metals, was consistent with expected elemental ratios, implying these metals were not primarily anthropogenic in origin. Factor 3, black carbon, was an acidic factor dominated by black carbon but with some sulfate contribution over the winter-haze season. The lack of K + associated with this factor, a Eurasian source, and limited known forest fire events coincident with this factor's peak suggested a predominantly anthropogenic combustion source. Factor 4, carboxylic acids, was dominated by formate and acetate with a moderate correlation to available sunlight and an oceanic and North American source. A robust identification of this factor was not possible; however, atmospheric photochemical reactions, ocean microlayer reaction, and biomass burning were explored as potential contributors. Factor 5, nitrate, was an acidic factor dominated by NO − 3 , with a likely Eurasian source and mid-winter peak. The isolation of NO − 3 on a separate factor may reflect its complex atmospheric processing, though the associated source region suggests possibly anthropogenic precursors. Factor 6, non-crustal metals, showed heightened loadings of Sb, Pb, and As, and correlation with other metals traditionally associated with industrial activities. Similar to Factor 3 and 5, this factor appeared to be largely Eurasian in origin. Factor 7, sulfate, was dominated by SO 2− 4 and MS with a fall peak and high acidity. Coincident volcanic activity and northern source regions may suggest a processed SO 2 source of this factor.

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Section: Factor 1: Sea Saltsupporting

confidence: 68%

Temporally delineated sources of major chemical species in high Arctic snow

et al. 2018

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“…If these crystals are then detached from the surface due to mechanical fracture they are likely to contribute substantially to the ice crystal population within the cloud. If surface production rates of ice crystals are similar to those reported by Xu et al (2013) for aerosol particles, then we postulate that these may be capable of explaining the high concentrations of ice crystals observed near the surface at the summit of JFJ. Due to the fragility of the "frost" crystals, often composed of needle habits or interlocking needles, relatively small variations in turbulence at the surface could cause their fragmentation and removal.…”

Section: Growth and Detachment Of Vapour Grown Surface Ice Or "Hoar Fsupporting

confidence: 62%

“…It is well known (see for example Xu et al, 2013, and references therein) that frost flowers forming on recently formed sea ice in the Arctic and Antarctic regions are an important source of atmospheric aerosol. It is envisaged that these frost flowers, which contain high concentrations of dissolved salt fragments, evaporate leaving behind suspended residues that form atmospheric aerosol (Perovich and Richter-Menge, 1994;Rankin et al, 2000).…”

Section: Growth and Detachment Of Vapour Grown Surface Ice Or "Hoar Fmentioning

confidence: 99%

The origins of ice crystals measured in mixed-phase clouds at the high-alpine site Jungfraujoch

et al. 2015

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Abstract. During the winter of 2013 and 2014 measurements of cloud microphysical properties over a 5-week period at the high-alpine site Jungfraujoch, Switzerland, were carried out as part of the Cloud Aerosol Characterisation Experiments (CLACE) and the Ice Nucleation Process Investigation and Quantification project (INUPIAQ). Measurements of aerosol properties at a second, lower site, Schilthorn, Switzerland, were used as input for a primary ice nucleation scheme to predict ice nuclei concentrations at Jungfraujoch. Frequent, rapid transitions in the ice and liquid properties of the clouds at Jungfraujoch were identified that led to large fluctuations in ice mass fractions over temporal scales of seconds to hours. During the measurement period we observed high concentrations of ice particles that exceeded 1000 L −1 at temperatures around −15 • C, verified by multiple instruments. These concentrations could not be explained using the usual primary ice nucleation schemes, which predicted ice nucleus concentrations several orders of magnitude smaller than the peak ice crystal number concentrations. Secondary ice production through the Hallett-Mossop process as a possible explanation was ruled out, as the cloud was rarely within the active temperature range for this process. It is shown that other mechanisms of secondary ice particle production cannot explain the highest ice particle concentrations. We describe four possible mechanisms that could lead to high cloud ice concentrations generated from the snowcovered surfaces surrounding the measurement site. Of these we show that hoar frost crystals generated at the cloud enveloped snow surface could be the most important source of cloud ice concentrations. Blowing snow was also observed to make significant contributions at higher wind speeds when ice crystal concentrations were < 100 L −1 .

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“…However, smaller crystals may show substantial fluxes at lower wind speeds. Aerosol fluxes from evaporated frost flowers have been estimated at 10 −6 m −2 s −1 at wind speeds as low as 1 m s −1 (Xu et al, 2013). Evaluating the impact of these mechanisms during MAC is challenging since most of the in-cloud sampling was performed over snow-covered sea ice, making it difficult to attribute local differences in the microphysics to the surface type.…”

Section: First Icementioning

confidence: 99%

In situ measurements of cloud microphysics and aerosol over coastal Antarctica during the MAC campaign

et al. 2017

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Abstract. During austral summer 2015, the Microphysics of Antarctic Clouds (MAC) field campaign collected unique and detailed airborne and ground-based in situ measurements of cloud and aerosol properties over coastal Antarctica and the Weddell Sea. This paper presents the first results from the experiment and discusses the key processes important in this region, which is critical to predicting future climate change.The sampling was predominantly of stratus clouds, at temperatures between −20 and 0 • C. These clouds were dominated by supercooled liquid water droplets, which had a median concentration of 113 cm −3 and an interquartile range of 86 cm −3 . Both cloud liquid water content and effective radius increased closer to cloud top. The cloud droplet effective radius increased from 4 ± 2 µm near cloud base to 8 ± 3 µm near cloud top.Cloud ice particle concentrations were highly variable with the ice tending to occur in small, isolated patches. Below approximately 1000 m, glaciated cloud regions were more common at higher temperatures; however, the clouds were still predominantly liquid throughout. When ice was present at temperatures higher than −10 • C, secondary ice production most likely through the Hallett-Mossop mechanism led to ice concentrations 1 to 3 orders of magnitude higher than the number predicted by commonly used primary ice nucleation parameterisations. The drivers of the ice crystal variability are investigated. No clear dependence on the droplet size distribution was found. The source of first ice in the clouds remains uncertain but may include contributions from biogenic particles, blowing snow or other surface ice production mechanisms.The concentration of large aerosols (diameters 0.5 to 1.6 µm) decreased with altitude and were depleted in air masses that originated over the Antarctic continent compared to those more heavily influenced by the Southern Ocean and sea ice regions. The dominant aerosol in the region was hygroscopic in nature, with the hygroscopicity parameter κ having a median value for the campaign of 0.66 (interquartile range of 0.38). This is consistent with other remote marine locations that are dominated by sea salt/sulfate.

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Frost flower aerosol effects on Arctic wintertime longwave cloud radiative forcing

Cited by 28 publications

References 63 publications

Temporally delineated sources of major chemical species in high Arctic snow

Temporally delineated sources of major chemical species in high Arctic snow

The origins of ice crystals measured in mixed-phase clouds at the high-alpine site Jungfraujoch

In situ measurements of cloud microphysics and aerosol over coastal Antarctica during the MAC campaign

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