Clim. Past Discuss., 8, 5455-5492, 2012
www.clim-past-discuss.net/8/5455/2012/
doi:10.5194/cpd-8-5455-2012
© Author(s) 2012. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Climate of the Past (CP). Please refer to the corresponding final paper in CP.
On the origin of multi-decadal to centennial Greenland temperature anomalies over the past 800 yr
T. Kobashi1,2, D. T. Shindell3, K. Kodera4,5, J. E. Box6,7, T. Nakaegawa4, and K. Kawamura1
1National Institute of Polar Research, 10-3 Midoricho, Tachikawa, Tokyo, 190-8518, Japan
2Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, 92093, USA
3NASA Goddard Institute for Space Studies, New York, New York, 10025, USA
4Meteorological Research Institute, Tsukuba, 305-0052, Japan
5Solar Terrestrial Environment Laboratory, Nagoya University, Nagoya, Japan
6Byrd Polar Research Center, The Ohio State University, Columbus, Ohio, 43210, USA
7Department of Geography, The Ohio State University, Columbus, OH 43210, USA

Abstract. The surface temperature of the Greenland ice sheet is among the most important climate variables for assessing how climate change may impact human societies associated with accelerating sea level rise. However, the causes of multi-decadal-to-centennial temperature changes in Greenland are not well understood, largely owing to short observational records. To examine the causes of the Greenland temperature variability, we calculated the Greenland temperature anomalies (GTA(G-NH)) over the past 800 yr by subtracting the standardised NH temperature from the standardised Greenland temperature. It decomposes the Greenland temperature variation into background climate (NH); Polar amplification; and Regional variability (GTA(G-NH)). The Central Greenland polar amplification factor as expressed by the variance ratio = Greenland/NH is 2.6 over the past 161 yr, and 3.3–4.2 over the past 800 yr. The GTA explains 31–35% of the variation of Greenland temperature in the multi-decadal-to-centennial time scale over the past 800 yr. Another orthogonal component of the Greenland and NH temperatures, GTP(G+NH) (Greenland temperature plus = standardized Greenland temperature + standardized NH temperature) exhibited the multi-decadal variations that were likely induced by large volcanic eruptions, increasing greenhouse gasses, and internal variation of climate. We found that the GTA(G-NH) has been influenced by solar-induced changes in atmospheric circulation patterns such as those produced by North Atlantic Oscillation/Arctic Oscillation (NAO/AO). Climate modelling indicates that the anomaly is also likely linked to solar-paced changes in the Atlantic meridional overturning circulation (AMOC) and to associated changes in northward oceanic heat transport.

Citation: Kobashi, T., Shindell, D. T., Kodera, K., Box, J. E., Nakaegawa, T., and Kawamura, K.: On the origin of multi-decadal to centennial Greenland temperature anomalies over the past 800 yr, Clim. Past Discuss., 8, 5455-5492, doi:10.5194/cpd-8-5455-2012, 2012.
 
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