Recent extreme light sea ice years in the Canadian Arctic Archipelago: 2011 and 2012 eclipse 1998 and 2007

Abstract

Abstract. Remarkably low mean September sea ice area in the Canadian Arctic Archipelago (CAA) was observed in 2011 (146 × 103 km2), a record-breaking level that was nearly exceeded in 2012 (150 × 103 km2). These values were lower than previous September records set in 1998 (200 × 103 km2) and 2007 (220 × 103 km2), and are ∼60% lower than the 1981–2010 mean September climatology. In this study, the processes contributing to the extreme light years of 2011 and 2012 were investigated, compared to previous extreme minima of 1998 and 2007, and contrasted against historic summer seasons with above average September ice area. The 2011 minimum was associated with positive June through September (JJAS) surface air temperature (SAT) and net solar radiation (K*) anomalies that facilitated rapid melt, coupled with atmospheric circulation that restricted multi-year ice (MYI) inflow from the Arctic Ocean into the CAA. The 2012 minimum was also associated with positive JJAS SAT and K* anomalies with coincident rapid melt, but further ice decline was temporarily mitigated by atmospheric circulation which drove Arctic Ocean MYI inflow into the CAA. Atmospheric circulation was comparable between 2011 and 1998 (impeding Arctic Ocean MYI inflow) and 2012 and 2007 (inducing Arctic Ocean MYI inflow). However, preconditioning was more apparent leading up to 2011 and 2012 than 1998 and 2007. The rapid melt process in 2011 and 2012 was more intense than observed in 1998 and 2007 because of the thinner ice cover being more susceptible to anomalous thermodynamic forcing. The thinner sea ice cover within the CAA in recent years has also helped counteract the processes that facilitate extreme heavy ice years. The recent extreme light years within the CAA are associated with a longer navigation season within the Northwest Passage.

Multiyear ice replenishment in the Canadian Arctic Archipelago: 1997–2013

“…The CAA has a history of recovering from light year ice years as illustrated in Figure b. The dramatic reduction in 1998 followed by a gradual return to heavier MYI conditions is perhaps the best example and has been the subject of numerous studies [e.g., Jeffers et al ., ; Atkinson et al ., ; Alt et al ., ; Howell et al ., ]. The fact that September 2013 experienced such a dramatic increase in total ice area which, occurred in a single year, followed the 2‐lightest ice years on record in the CAA since 1968 and was primarily attributed to CAA MYI‐Oct‐1 warrants some additional investigation.…”

“…Knowledge of MYI within the CAA is important given, it is the most significant hazard to navigation within the Northwest Passage, even when present only in small amounts. There is a strong link between the decreased presence of MYI within the CAA and a longer navigation season for the Parry Channel route of Northwest Passage, that is especially pronounced since 2007 [ Howell et al ., ]. Despite a longer navigation season, the Parry Channel route is only temporarily clear of MYI for a few weeks during the melt season as the predominant modes of atmospheric circulation facilitate MYI inflow from the higher latitudes [ Howell et al ., ].…”

“…There is a strong link between the decreased presence of MYI within the CAA and a longer navigation season for the Parry Channel route of Northwest Passage, that is especially pronounced since 2007 [ Howell et al ., ]. Despite a longer navigation season, the Parry Channel route is only temporarily clear of MYI for a few weeks during the melt season as the predominant modes of atmospheric circulation facilitate MYI inflow from the higher latitudes [ Howell et al ., ]. The latter process is of concern because certain types of vessel traffic (i.e., nonice strengthened pleasure crafts) within the Canadian Arctic have increased significantly since 1990 [ Pizzolato et al ., ].…”

“…Moreover, the time series of mean September sea ice area within the CAA from 1968 to 2013 illustrates the heavy and stable ice conditions that were apparent in the early period of the record have relaxed from 2006 to 2012 (Figure b). Notably, 2011 and 2012 broke all previous record low ice years within the CAA with September ice conditions falling ∼60% lower than the 1981–2010 climatology (Figure b) [ Howell et al ., ]. A more direct and up‐to‐date assessment of MYI replenishment within the CAA is necessary.…”

A comparison of tracking methods for extreme cyclones in the Arctic basin

“…Another aspect of this issue, which has been revealed in the recent literature, is that the nature of the sea ice response to storms depends very much on the preconditioning that the region has undergone (e.g. Howell et al, 2013;Parkinson and Comiso, 2013;Zhang et al, 2013). It is important to note that these extreme storms do not always have an impact on the surface fluxes.…”