Increased Greenland melt triggered by large-scale, year-round cyclonic moisture intrusions.

Oltmanns, Marilena , Straneo, Fiammetta and Tedesco, Marco (2019) Increased Greenland melt triggered by large-scale, year-round cyclonic moisture intrusions. Open Access The Cryosphere, 13 . pp. 815-825. DOI 10.5194/tc-13-815-2019.

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Abstract

Surface melting is a major driver of Greenland's mass loss. Yet, the mechanisms that trigger melt are still insufficiently understood because seasonally based studies blend processes initiating melt with positive feedbacks. Here, we focus on the triggers of melt by examining the synoptic atmospheric conditions associated with 313 rapid melt increases, detected in a satellite-derived melt extent product, equally distributed throughout the year over the period 1979–2012. By combining reanalysis and weather station data, we show that melt is initiated by a cyclone-driven, southerly flow of warm, moist air, which gives rise to large-scale precipitation. A decomposition of the synoptic atmospheric variability over Greenland suggests that the identified, melt-triggering weather pattern accounts for ∼40 % of the net precipitation, but increases in the frequency, duration and areal extent of the initiated melting have shifted the line between mass gain and mass loss as more melt and rainwater run off or accumulate in the snowpack. Using a regional climate model, we estimate that the initiated melting more than doubled over the investigated period, amounting to ∼28 % of the overall surface melt and revealing that, despite the involved mass gain, year-round precipitation events are participating in the ice sheet's decline.

Document Type: Article
Funder compliance: info:eu-repo/grantAgreement/EC/H2020/727852 ; info:eu-repo/grantAgreement/EC/H2020/633211
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
Scripps
Refereed: Yes
Open Access Journal?: Yes
DOI etc.: 10.5194/tc-13-815-2019
ISSN: 1994-0416
Projects: Blue-Action, AtlantOS
Date Deposited: 11 Dec 2018 08:13
Last Modified: 23 May 2019 08:04
URI: http://oceanrep.geomar.de/id/eprint/44927

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