On the spatiotemporal behavior of sea ice concentration anomalies in the Northern Hemisphere

Reduction in the aerial extent and thickness of sea ice in the Northern Hemisphere is an important element in understanding how the arctic responds to global‐scale climate variability and change. Previous studies have demonstrated a significant reduction in minimum sea ice extent [Serreze et al., 2003] with record reduction in 2005. Observational studies attribute this phenomenon to variations in sea level pressure and large‐scale atmospheric teleconnection patterns such as the Northern Annular Mode (NAM) [Deser et al., 2000; Serreze et al., 2003]. In this study we examine variations in sea ice in the context of spatiotemporal variability of sea ice concentration (SIC) anomalies in the Northern Hemisphere during the onset of ice formation. Examined in particular are timescales associated with coherent regions of persistence in an e‐folding time spatial distribution (EFSD). Annual variations of weekly SIC anomalies are studied and spatial relations between positive and negative SIC anomalies are explored on a hemispheric scale. The results from this investigation demonstrate coherent SIC persistence patterns throughout the Northern Hemisphere, with timescales ranging from 3 to 7 weeks. Spatial correspondence between negative trends in SIC anomalies and the EFSD suggests that the same mechanism may be responsible for both increased ice reduction and persistence in this region. Examination of spatial coherence in SIC anomalies indicates that maximum SIC anomalies prevail near the Kara Sea, Beaufort Sea, and Chukchi Sea regions during late summer/early fall from 1979 to 2004. A latitudinal assessment at 80°, 70°, and 60°N indicates a poleward shift and retreat in SIC anomalies, while also underlining the decadal shift in variability often attributed to the NAM.