Journal Article
Atmospheric Chemistry and Physics, vol. 18, iss. 24, pp. 18023-18042, 2018
Authors
Jessie M. Creamean, Rachel M. Kirpes, Kerri A. Pratt, Nicholas J. Spada, Maximilian Maahn, Gijs de Boer, Russell C. Schnell, Swarup China
Abstract
Abstract. Aerosols that serve as ice nucleating particles (INPs) have the potential to
modulate cloud microphysical properties and can therefore impact cloud
radiative forcing (CRF) and precipitation formation processes. In remote
regions such as the Arctic, aerosol–cloud interactions are severely
understudied yet may have significant implications for the surface energy
budget and its impact on sea ice and snow surfaces. Further, uncertainties in
model representations of heterogeneous ice nucleation are a significant
hindrance to simulating Arctic mixed-phase cloud processes. We present
results from a campaign called INPOP (Ice Nucleating Particles at Oliktok
Point), which took place at a US Department of Energy Atmospheric Radiation
Measurement (DOE ARM) facility in the northern Alaskan Arctic. Three time-
and size-resolved aerosol impactors were deployed from 1 March to 31 May 2017
for offline ice nucleation and chemical analyses and were co-located with
routine measurements of aerosol number and size. The largest particles (i.e.,
≥ 3 µm or “coarse mode”) were the most efficient INPs by
inducing freezing at the warmest temperatures. During periods with snow- and
ice-covered surfaces, coarse mode INP concentrations were very low (maximum
of 6 × 10−4 L−1 at −15 ∘C), but higher
concentrations of warm-temperature INPs were observed during late May
(maximum of 2 × 10−2 L−1 at −15 ∘C). These
higher concentrations were attributed to air masses originating from over
open Arctic Ocean water and tundra surfaces. To our knowledge, these results
represent the first INP characterization measurements in an Arctic oilfield
location and demonstrate strong influences from mineral and marine sources
despite the relatively high springtime pollution levels. Ultimately, these
results can be used to evaluate the anthropogenic and natural influences on
aerosol composition and Arctic cloud properties.
