Modeled Response of Greenland Snowmelt to the Presence of Biomass Burning‐Based Absorbing Aerosols in the Atmosphere and Snow

• Published in: Journal of Geophysical Research: Atmospheres
• Main Authors: Ward, Jamie L., Flanner, Mark G., Bergin, Mike, Dibb, Jack E., Polashenski, Chris M., Soja, Amber J., Thomas, Jennie L.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Wiley Periodicals, Inc. 2018
• Subjects: snowmelt; light‐absorbing aerosols; Greenland Ice Sheet; Atmospheric and Oceanic Sciences; Science; Greenland; Arctic; Ice Sheet; The Cryosphere
• Online Access: https://hdl.handle.net/2027.42/144656; https://doi.org/10.1029/2017JD027878

Biomass burning produces smoke aerosols that are emitted into the atmosphere. Some smoke constituents, notably black carbon, are highly effective light‐absorbing aerosols (LAA). Emitted LAA can be transported to high‐albedo regions like the Greenland Ice Sheet (GrIS) and affect local snowmelt. In the summer, the effects of LAA in Greenland are uncertain. To explore how LAA affect GrIS snowmelt and surface energy flux in the summer, we conduct idealized global climate model simulations with perturbed aerosol amounts and properties in the GrIS snow and overlying atmosphere. The in‐snow and atmospheric aerosol burdens we select range from background values measured on the GrIS to unrealistically high values. This helps us explore the linearity of snowmelt response and to achieve high signal‐to‐noise ratios. With LAA operating only in the atmosphere, we find no significant change in snowmelt due to the competing effects of surface dimming and tropospheric warming. Regardless of atmospheric LAA presence, in‐snow black carbon‐equivalent mixing ratios greater than ~60 ng/g produce statistically significant snowmelt increases over much of the GrIS. We find that net surface energy flux changes correspond well to snowmelt changes for all cases. The dominant component of surface energy flux change is solar energy flux, but sensible and longwave energy fluxes respond to temperature changes. Atmospheric LAA dampen the magnitude of solar radiation absorbed by in‐snow LAA when both varieties are simulated. In general, the significant melt and surface energy flux changes we simulate occur with LAA quantities that have never been recorded in Greenland.Key PointsWe compare the effects of in‐snow and atmospheric light‐absorbing aerosols on Greenland’s climateAtmospheric light‐absorbing aerosols warm the troposphere and dim the surface, which causes nonlinear snowmelt changes across GreenlandFor qualitatively similar burdens, snowmelt on Greenland is more sensitive to in‐snow light‐absorbing aerosols than atmospheric aerosols ...