JP2.5
Mechanisms of decadal and interdecadal Arctic climate variability in the Community Climate System Model CCSM2
Hugues Goosse, Universite Catholique de Louvain, Louvain-la-Neuve, Belgium; and M. M. Holland
Several mechanisms have been proposed to explain natural climate variability in the Arctic. These include the influence of the North Atlantic Oscillation/Arctic Oscillation (NAO/AO), anticyclonic/cyclonic regimes, changes in the oceanic and atmospheric North Atlantic-Arctic exchange, and changes in the ocean thermohaline circulation. Many aspects of these mechanisms are likely interrelated. For example, changes in Arctic-North Atlantic exchange appear to be related to the NAO/AO. However, other factors may also contribute to variability in this exchange and the influence of the NAO/AO on these processes may not be robust over long time scales. In this study, we present a common framework for assessing different mechanisms of Arctic climate variability. In particular, we examine the influence and interrelation of the above mechanisms in a long climate integration of the Community Climate System Model, version 2 (CCSM2). The analysis is based on the time series of surface air temperature integrated northward of 70 N, which serves as a useful proxy for general Arctic climate conditions. This gives a large-scale view of the evolution of Arctic climate. We find that changes in oceanic exchange and heat transport in the Barents Sea dominate in forcing the Arctic surface air temperature variability. Changes in atmospheric circulation are consistent with a wind forcing of this variability, while changes in the thermohaline driven circulation are more weakly related. Over some time periods, the NAO/AO is significantly related to these changes in Arctic climate conditions. However, this is not robust over longer-timescales.
Joint Poster Session 2, Formal Poster Viewing - High Latitude Climate Variability and Change (Joint with the Eight Conference on Polar Meteorology and the 16th symposium on Global Change & Climate Variations)
Thursday, 13 January 2005, 9:45 AM-11:00 AM
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