Dust-driven cloud phase changes may impact summertime cooling over
Arctic sea ice
Abstract
Cloud phase has important impacts on Arctic surface temperatures, and
there is substantial circumstantial evidence that dust aerosols have
strong impacts on cloud phase over the Arctic on a regional scale. We
used seven years of satellite observations and model and reanalysis
products to control for co-varying meteorology, and to assess how dust
and other aerosols impact cloud phase over the summertime sea ice. We
focus on clouds at 3 km, where dust modeling is most accurate. Dust
aerosols caused about 4.5% of clouds below -15 °C to change phase, with
smaller effects at higher temperatures. Sulfate has a smaller impact on
cloud phase. Dust is associated with cloud-mediated surface cooling of
up to a 6.3 W m-2 below single-layer clouds at ~3 km in
June. Lastly, we discuss the optimal meteorological conditions for
future in situ studies to maximize insight into the mechanisms driving
the observed dust effects.