Master thesis defense by Majbritt W. Sørensen – Niels Bohr Institute - University of Copenhagen

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Master thesis defense by Majbritt W. Sørensen

Evaluation of the 20th Century Reanalysis for the Greenland area - using meteorological observations and ice core data

The 20th Century Reanalysis Project (20CR) is the first project to have produced an atmospheric reanalysis covering the time period all the way back to 1871. It assimilate surface pressure observations and uses sea surface temperatures and the sea ice distribution as boundary conditions. The spatial and temporal resolution is 2x2 degrees and 6 hours, respectively.

The 20CR has been globally tested against previous reanalyses covering the post World War II era and meteorological observations, and is evaluated to perform at the same level as those previous reanalyses products. But when zooming in on the Artic area no evaluation have been conducted specifically for this area all the way back to 1871. Thus evaluating the 20CR for the Greenland area for the entire time span will be the aim of this thesis.

A comparison between reanalysis output and observations of temperature and precipitation, in annual mean, around the coast of Greenland will be conducted along with a comparison of the accumulation at NGRIP (North Greenland Ice Core Project) and the precipitation rate obtained from the 20CR. The accumulation at NGRIP will be obtained from six cores drilled in the years 1996-2004 (five shallow cores and one deep core). A noise level analysis will be conducted on the ice cores beforehand to discover whether or not a common signal is present. Finally the reanalysis output will be used to explain the variations measured for the isotopic composition of stable water measured in the shallow cores at NGRIP.

Vejleder: Bo M. Vinther
Censor: Katrine K. Andersen