Increased Greenland melt triggered by large-scale, year-round cyclonic moisture intrusions
<p>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 synopt...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-03-01
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| Series: | The Cryosphere |
| Online Access: | https://www.the-cryosphere.net/13/815/2019/tc-13-815-2019.pdf |
| Summary: | <p>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 <span class="inline-formula">∼40</span> % 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 <span class="inline-formula">∼28</span> % 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.</p> |
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| ISSN: | 1994-0416 1994-0424 |