Observational Studies of Aerosol–Cloud Interactions along the North Slope of Alaska (Invited Presentation)

The impacts of natural and anthropogenic aerosol particles on cloud characteristics, including radiative properties, precipitation intensity, and lifetime remain a challenge to understand and quantify. Such influence is particularly notable in high latitude regions due to the stark contrast between polluted scenarios and the relatively clean background state, with this gradient resulting in enhanced influence of aerosols over cloud properties. Additionally, small changes to the impacts of clouds on surface energy exchange can have large implications on a region known for extensive cloud cover whose atmospheric state exhibits large sensitivities to the surface energy budget, and where small shifts in temperature may result in dramatic departures in the surface energy budget through modification of surface albedos. To better understand the role that aerosol particles play in this puzzle and the sources of aerosols involved, we are using a variety of observational perspectives to gain new insight into these interactions.

In this work, we present observational analyses that shed light on the interplay between aerosols and cloud microphysical and radiative properties in Northern Alaska. Using measurements from surface-based US Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program observatories at Oliktok Point and Utquiagvik (formerly Barrow) Alaska, together with airborne measurements, we will demonstrate:

1) That localized anthropogenic emissions resulting from oil and gas exploration activities in the Prudhoe Bay region notably impact cloud structure and thereby alter radiative transfer in the atmosphere, and

2) That aerosol loading plays a role in the modulation of precipitation from mixed-phase clouds, thereby impacting surface albedo and cloud dynamics

These findings can have implications on future Arctic climate states. For one, the expansion of industrial activities in the Arctic including energy exploration and shipping will increase localized pollution sources. Additionally, the anticipated expansion of open water areas in the central Arctic will contribute to emissions from the ocean surface which have the potential to alter precipitation characteristics.