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Unprecedented Atmospheric Conditions (1948–2019) Drive the 2019 Exceptional Melting Season Over the Greenland Ice Sheet

Authors :
Marco Tedesco
Xavier Fettweis
Source :
The Cryosphere. 14(4)
Publication Year :
2020
Publisher :
United States: NASA Center for Aerospace Information (CASI), 2020.

Abstract

Understanding the role of atmospheric circulation anomalies on the surface mass balance of the Greenland ice sheet (GrIS) is fundamental for improving estimates of its current and future contributions to sea level rise. Here, we show, using a combination of remote sensing observations, regional climate model outputs, reanalysis data, and artificial neural networks, that unprecedented atmospheric conditions (1948–2019) occurring in the summer of 2019 over Greenland promoted new record or close-to-record values of surface mass balance (SMB), runoff, and snowfall. Specifically, runoff in 2019 ranked second within the 1948–2019 period (after 2012) and first in terms of surface mass balance negative anomaly for the hydrological year 1 September 2018–31 August 2019. The summer of 2019 was characterized by an exceptional persistence of anticyclonic conditions that, in conjunction with low albedo associated with reduced snowfall in summer, enhanced the melt–albedo feedback by promoting the absorption of solar radiation and favored advection of warm, moist air along the western portion of the ice sheet towards the north, where the surface melt has been the highest since 1948. The analysis of the frequency of daily 500 hPa geopotential heights obtained from artificial neural networks shows that the total number of days with the five most frequent atmospheric patterns that characterized the summer of 2019 was 5 standard deviations above the 1981–2010 mean, confirming the exceptional nature of the 2019 season over Greenland.

Subjects

Subjects :
Meteorology And Climatology

Details

Language :
English
ISSN :
19940424 and 19940416
Volume :
14
Issue :
4
Database :
NASA Technical Reports
Journal :
The Cryosphere
Notes :
80NSSC17K0351, , NNX17AH04G, , F.R.S.FNRS 2.5020.11, , Wallonia 1117545
Publication Type :
Report
Accession number :
edsnas.20205000922
Document Type :
Report
Full Text :
https://doi.org/10.5194/tc-14-1209-2020