Atmospheric blocking drives recent albedo change across the western Greenland ice sheet percolation zone
Abstract
Greenland Ice Sheet (GrIS) albedo has decreased over recent decades, contributing to enhanced surface melt and mass loss. However, it remains unclear whether GrIS darkening is due to snow grain size increases, higher concentrations of light-absorbing impurities (LAIs), or a combination. Here, we assess albedo controls in the western GrIS percolation zone using in situ albedo, LAI, and grain size measurements. We find a significant correlation between albedo and snow grain size (p < 0.01), but not with LAIs. Modeling corroborates that LAI concentrations are too low to significantly reduce albedo, but larger grain sizes could reduce albedo by at least ∼3%. Strong atmospheric blocking increases grain sizes and reduces albedo through increased surface temperature, fewer storms, and higher incoming shortwave radiation. These findings clarify the mechanisms by which anomalously strong blocking contributed to recent GrIS albedo decline and mass loss, highlighting the importance of improving projections of future blocking.
Department
Earth Systems Research Center
Publication Date
5-17-2021
Journal Title
Geophysical Research Letters
Publisher
AGU
Digital Object Identifier (DOI)
https://dx.doi.org/10.1029/2021GL092814
Document Type
Article
Recommended Citation
Lewis, G., E. Osterberg, R. Hawley, H. P. Marshall, T. Meehan, K. Graeter, F. McCarthy, T. Overly, Z. Thundercloud, D. Ferris, B. Koffman, and J. Dibb (2021), Atmospheric blocking drives recent albedo change across the western Greenland ice sheet percolation zone, Geophysical Research Letters, 48, e2021GL092814. https:/doi.org/10.1029/2021GL092814.