Black carbon and other light-absorbing impurities in snow in the Chilean Andes

Penny M. Rowe, Raul R. Cordero, Stephen G. Warren, Emily Stewart, Sarah J. Doherty, Alec Pankow, Michael Schrempf, Gino Casassa, Jorge Carrasco, Jaime Pizarro, Shelley MacDonell, Alessandro Damiani, Fabrice Lambert, Roberto Rondanelli, Nicolas Huneeus, Francisco Fernandoy, Steven Neshyba

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18 Citations (Scopus)

Abstract

Vertical profiles of black carbon (BC) and other light-absorbing impurities were measured in seasonal snow and permanent snowfields in the Chilean Andes during Austral winters 2015 and 2016, at 22 sites between latitudes 18°S and 41°S. The samples were analyzed for spectrally-resolved visible light absorption. For surface snow, the average mass mixing ratio of BC was 15 ng/g in northern Chile (18–33°S), 28 ng/g near Santiago (a major city near latitude 33°S, where urban pollution plays a significant role), and 13 ng/g in southern Chile (33–41°S). The regional average vertically-integrated loading of BC was 207 µg/m 2 in the north, 780 µg/m 2 near Santiago, and 2500 µg/m 2 in the south, where the snow season was longer and the snow was deeper. For samples collected at locations where there had been no new snowfall for a week or more, the BC concentration in surface snow was high (~10–100 ng/g) and the sub-surface snow was comparatively clean, indicating the dominance of dry deposition of BC. Mean albedo reductions due to light-absorbing impurities were 0.0150, 0.0160, and 0.0077 for snow grain radii of 100 µm for northern Chile, the region near Santiago, and southern Chile; respective mean radiative forcings for the winter months were 2.8, 1.4, and 0.6 W/m 2 . In northern Chile, our measurements indicate that light-absorption by impurities in snow was dominated by dust rather than BC.

Original languageEnglish
Article number4008
JournalScientific Reports
Volume9
Issue number1
DOIs
Publication statusPublished - 1 Dec 2019

ASJC Scopus subject areas

  • General

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