Dust Transport into the Arctic: Time for Routine In Situ Measurements

Abstract:

Long range transport of Asian dust into the Arctic has been observed for many years. The dust often contains anthropogenic aerosols such as black carbon. Radiation measurements beneath a dust layer over the NOAA Barrow Observatory showed cooling of the surface by >5 Wm⁻²/day with calculated heating of 3 K/day within the layer. Airborne vertical profiles of aerosols were conducted across the Arctic Basin during the Arctic Gas and Aerosol Sampling Program (AGASP, 1983-91) and the Aerosol, Radiation, and Cloud Processes Affecting Arctic Climate (ARCPAC, 2008). The most salient observation from these profiles was that aerosol concentrations above the top of the marine boundary (cloud) layer were often an order of magnitude greater than within the boundary layer or at the surface.

Lidar measurements from Barrow and Alert show that there are layers of dust and haze flowing into the Arctic Basin that are not detected at the surface or are measured only as minor aerosol perturbations. There are programs conducting aerosol measurements in the Arctic with UAVs, but these are limited in scope and not conducted on a year around basis. Models of Arctic aerosol distributions and concentrations do not adequately describe either surface aerosol measurements or aerosols above the marine boundary layer. Climate models are not able to adequately describe the forces involved in the accelerating melting of the Arctic ice cap. There are conjectures that dust and black carbon aerosols on the ice may be contributing to this melting.

Considering their importance in Arctic climate forcing, we suggest that atmospheric and climate modeling scientists have an obligation to develop a plan for sustained profiling of aerosol optical properties (light scattering and absorption) and cloud nucleating properties (CCN and IN) in the Arctic. These profiles need to extend from near the surface through the marine cloud layer and into the upper reaches of the free troposphere