Show simple item record

dc.contributor.author
Hermann, Mauro
dc.contributor.supervisor
Papritz, Lukas
dc.contributor.supervisor
Wernli, Heini
dc.date.accessioned
2019-06-24T13:53:24Z
dc.date.available
2019-06-18T05:48:45Z
dc.date.available
2019-06-18T06:12:14Z
dc.date.available
2019-06-24T13:53:24Z
dc.date.issued
2019-04-05
dc.identifier.uri
http://hdl.handle.net/20.500.11850/348060
dc.identifier.doi
10.3929/ethz-b-000348060
dc.description.abstract
The acceleration of mass loss from the Greenland Ice Sheet (GrIS) since the late 1990s was primarily driven by increased surface melt, partly concentrated in single extreme melt events. A textbook example was observed around 12 July 2012 (EV69), when almost the entire GrIS was melting, including Summit Station at 3216 m in the dry inland plateau. The melt event coincided with strong meridional air mass transport towards the GrIS followed by a Greenland blocking, which resembles the anomalous synoptic pattern that became increasingly frequent in the North Atlantic region in the last two decades. Here, we investigate the atmospheric forcing of extraordinary melt periods by assessing the main dynamical and thermodynamic processes that cause so-called warm events. We present an ERA-Interim-based climatology of 77 Greenland warm events affecting the high accumulation area in 1979-2017. These events became longer and more frequent during the study period. With Lagrangian backward trajectories started from the lowermost ~500 m above the GrIS, we identify transport from a climatologically warmer region as key process for Greenland warm events. With an about 15° latitude more southerly air mass origin and subsidence-induced adiabatic warming, this process is twice as important as diabatic heating to the final warm anomaly over North and East Greenland. In South and West Greenland, major contributions come from ascending air masses and in the Southwest, warm events are dominated by orographically induced latent heating as opposed to transport. 70-85% of all warm events go along with a Greenland blocking, which we suggest induces additional melt via modulations of the surface energy budget not captured by our Lagrangian methodology. We further qualify the importance of the concurrent US Great Plains heatwave for EV69. In contrast to previous studies, we find that air masses arriving over the GrIS during EV69 mostly originated from the Canadian Arctic, Newfoundland and the subtropical North Atlantic, which were partly also anomalously warm. Given the relevance of atmospheric blocking for Greenland warm events and their link to anomalously warm summers, it is crucial, as we argue, to better understand the modification of inter-annual climate variability by climate change in the North Atlantic region, to more accurately predict future GrIS mass loss. Also, more research on cloud radiative effects is needed to capture the GrIS-wide variability of surface energy budget anomalies during Greenland blocking.
en_US
dc.format
application/pdf
en_US
dc.language.iso
en
en_US
dc.publisher
ETH Zurich, Institute for Atmospheric and Climate Science (IAC)
en_US
dc.rights.uri
http://rightsstatements.org/page/InC-NC/1.0/
dc.subject
atmospheric dynamics
en_US
dc.subject
Greenland
en_US
dc.subject
warm events
en_US
dc.subject
ERA-Interim
en_US
dc.subject
backward trajectories
en_US
dc.title
A Lagrangian Analysis of the Dynamical and Thermodynamic Drivers of Greenland Warm Events during 1979-2017
en_US
dc.type
Master Thesis
dc.rights.license
In Copyright - Non-Commercial Use Permitted
dc.date.published
2019-06-24
ethz.size
109 p.
en_US
ethz.code.ddc
DDC - DDC::5 - Science::500 - Natural sciences
en_US
ethz.publication.place
Zurich
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02350 - Dep. Umweltsystemwissenschaften / Dep. of Environmental Systems Science::02717 - Institut für Atmosphäre und Klima / Inst. Atmospheric and Climate Science::03854 - Wernli, Johann Heinrich / Wernli, Johann Heinrich
en_US
ethz.leitzahl.certified
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02350 - Dep. Umweltsystemwissenschaften / Dep. of Environmental Systems Science::02717 - Institut für Atmosphäre und Klima / Inst. Atmospheric and Climate Science::03854 - Wernli, Johann Heinrich / Wernli, Johann Heinrich
en_US
ethz.date.deposited
2019-06-18T05:48:53Z
ethz.source
FORM
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2019-06-24T13:56:13Z
ethz.rosetta.lastUpdated
2019-06-24T13:56:13Z
ethz.rosetta.versionExported
true
ethz.COinS
ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.atitle=A%20Lagrangian%20Analysis%20of%20the%20Dynamical%20and%20Thermodynamic%20Drivers%20of%20Greenland%20Warm%20Events%20during%201979-2017&rft.date=2019-04-05&rft.au=Hermann,%20Mauro&rft.genre=unknown&rft.btitle=A%20Lagrangian%20Analysis%20of%20the%20Dynamical%20and%20Thermodynamic%20Drivers%20of%20Greenland%20Warm%20Events%20during%201979-2017
 Search print copy at ETH Library

Files in this item

Thumbnail

Publication type

Show simple item record