Synoptic activity associated with sea ice variability in the Arctic

Abstract

Relationships between synoptic activity and sea ice variability in the Arctic are studied using self-organizing maps (SOMs) to categorize observed weather patterns over the 1979-2013 period. The European Centre for Medium-Range Weather Forecasts Re-Analysis Interim provides the daily averaged sea level pressures from which the SOMs are computed. Time series of frequencies and durations of synoptic weather patterns are correlated with two sea ice metrics, Fram Strait ice outflow and year-to-year changes in September pan-Arctic sea ice extent. When compared to climate indices commonly used to predict sea ice, the Arctic Oscillation, North Atlantic Oscillation, and Arctic Dipole, some SOM patterns correlate as or more strongly with sea ice metrics. For example, Beaufort High synoptic patterns are increasing in frequency in spring and their summer frequencies are associated with ice loss. Arctic high-pressure patterns are linked to ice loss through pressure gradients conducive to ice export. The phase lags between the SOM occurrences and sea ice variability offer the potential for augmentation of other approaches to seasonal sea ice prediction.

Arctic Summer Sea Ice Melt and Related Atmospheric Conditions in Coupled Regional Climate Model Simulations and Observations

“…In addition, the strong SLP gradient with the accompanied Siberian low (“dipole pattern”) favors ice drift in the Transpolar Drift Stream. This is consistent with our correlation result and other studies (e.g., Mills & Walsh, ; Screen et al, ), and exemplified by summer 2007 (e.g., Serreze et al, ; Wang et al, ). In addition, we find that a strong Beaufort High and a cyclone located over northern central Siberia/Taymyr peninsula (patterns (1,2), (3,0), (3,1)) can be associated with HMR conditions.…”

“…The two most frequently occurring SLP patterns are labeled (1,0) which represents low pressure over the whole Arctic with a minimum over the central Arctic Ocean and Siberia, and (3,4) which has high pressure over the western part of the Arctic Ocean accompanied with low pressure over Siberia. These are consistent with the “Weak Features” and “Beaufort Highs/Eurasian Lows” most frequent summer patterns identified by Mills and Walsh ().…”

Linkages between Arctic summer circulation regimes and regional sea ice anomalies

“…This application uses the ERA‐Interim [ ECMWF , ; Dee et al ., ] daily mean sea level pressure (SLP) anomaly data for 1979–2014, interpolated to the 50 km EASE grid. This is congruent with the Arctic‐wide SOM of Mills and Walsh [], and our approach was verified by reproducing this SOM (not shown.) However, for the present paper, we only analyze the circulation for the months July, August, and September.…”

“…It is well known that the atmospheric circulation patterns play an important role in determining ice edge variability [ Serreze et al ., ; Maslanik et al ., ; Ogi and Wallace , ; Mills and Walsh , ]. The surface wind largely drives the sea ice circulation, affecting, for example, whether the ice motion is offshore or onshore, and the overall thickness distribution.…”

Synoptic conditions during summertime temperature extremes in Alaska

“…A final step in the synoptic circulation typing analysis is a grouping of similar patterns into five main clusters as was done for winter extremes in Cassano et al () and in other SOM studies (e.g. Leloup et al , , ; Finnis et al , ; Seefeldt and Cassano, ; Mills and Walsh, ; Nigro and Cassano, , ; Shan et al , ; DuVivier and Cassano, ). The clusters are indicated by the outlines and labelled on Figures and .…”