An assessment of the association between the Arctic Oscillation and Northern Hemisphere temperature

The Arctic Oscillation (AO) has been associated with changes in temperature on both the local and hemispheric scale. We assess the AO-temperature relationship using observational data and output from a long coupled atmosphere-ocean model integration. The regional temperature anomalies associated with a particular phase of the AO are simulated well by the model. Because the characteristic signature of the AO contains both positive and negative temperature anomalies, the dependence of extratropical Northern Hemisphere temperature on the AO is relatively weak and varies in magnitude during the course of the model integration. Estimates of the AO-temperature relationship derived from observations also exhibit variations during the period of instrumental data, some of which are the result of biased spatial sampling during the late 19th and early 20th centuries. Because of these factors, the contribution of systematic changes in the AO to observed climate trends may be difficult to estimate.