Correlated Patterns of Arctic Sea Ice Concentration and Climate Variables: Insight into the Causes of Arctic Sea Ice Decline

We have conducted a principal components analysis of 30 years of arctic monthly sea ice concentration data (1979–2009) for both the winter maximum period (JFMA) and summer minimum period (JASO) to extract the three predominant ice concentration spatial patterns for each season (each with an arbitrary, positive and negative phase). Climate data extracted for the years with high loadings of the individual patterns provide insight into the underlying circulation and air temperature conditions associated with each of them. Several of the ice-component-derived climate patterns show changes in prevalence over the three decades of the analysis period, suggesting ongoing shifts in climatic conditions leading to sea ice loss. The first component pattern for summer, in its positive phase, appears to be related to high air temperatures in the arctic basin; the positive phase loading has increased in recent years. The second summer component pattern is primarily related to the strength of the trans-polar drift and air circulation anomalies, and its negative phase, with strong transpolar drift, is increasingly common over the study period. For the winter season, the primary component pattern is closely tied to the Arctic Oscillation, and both were dominantly positive in the mid-1980s and early 1990s. The second winter pattern appears to be related to strong Arctic warming and its negative phase associated with warm years, has increased in prevalence over the study period. A comparison of the summer PC patterns to the 2009 summer concentrations (not included in the PC analysis) shows that the patterns continue to explain recent ice changes.