A Comparison of Global Climate Reanalysis and Climate of South Greenland and the North Atlantic
Global climate reanalysis models are regularly used in many scientific fields concerning climate and atmospheric observation. This thesis utilizes reanalysis models in two chapters in order to gain insight into North Atlantic climate teleconnections and their relation to precipitation across South G...
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DigitalCommons@UMaine
2016
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| Online Access: | https://digitalcommons.library.umaine.edu/etd/2537 https://digitalcommons.library.umaine.edu/context/etd/article/3588/viewcontent/M_JAuger_Revisions.pdf |
| Summary: | Global climate reanalysis models are regularly used in many scientific fields concerning climate and atmospheric observation. This thesis utilizes reanalysis models in two chapters in order to gain insight into North Atlantic climate teleconnections and their relation to precipitation across South Greenland. This first chapter of this thesis compares the four most recent reanalysis models – ECMWF Reanalysis Interim (ERA-I), NCEP Climate Forecast System Reanalysis (CFSR), JMA 55-year Reanalysis (JRA-55), and NASA Modern-Era Retrospective Analysis for Research and Applications (MERRA) – and develops from these models a monthly-mean ensemble average of common meteorological variables for the period 1979-2013. Results from this analysis shows that the reanalyses are in good agreement above the friction layer in the atmosphere, whereas significant model differences are found near the surface. The second chapter of this thesis utilizes the previous results to investigate the relative importance of the North Atlantic Oscillation (NAO) (high-frequency atmospheric) and the Atlantic Multidecadal Oscillation (AMO) (low-frequency sea-surface temperature) climate teleconnections as well as the Icelandic Low, Azores High, and blocking patterns in modulating precipitation across South Greenland. Key findings from this second chapter include: 1) years of extreme high and low precipitation in West Greenland are linked with the Icelandic Low, blocking patterns, and the westerly winds; and, 2) the long-term precipitation signal shows an increase of annual total precipitation and variability over southwest Greenland after the year 1995, suggesting an influence from the increase in both temperature and meridional flux of moisture and heat accompanied by a decrease in the zonal component of the westerlies. This work could be expanded upon in the future by identifying changes in synoptic fields during years of extreme high and low precipitation. Output from the four-member global climate reanalysis ensemble produced as part of this ... |
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