The Melting Arctic and Midlatitude Weather Patterns: Are They Connected?*

Abstract

The potential of recent Arctic changes to influence hemispheric weather is a complex and controversial topic with considerable uncertainty, as time series of potential linkages are short (,10 yr) and understanding involves the relative contribution of direct forcing by Arctic changes on a chaotic climatic system. A way forward is through further investigation of atmospheric dynamic mechanisms. During several exceptionally warm Arctic winters since 2007, sea ice loss in the Barents and Kara Seas initiated eastward-propagating wave trains of high and low pressure. Anomalous high pressure east of the Ural Mountains advected Arctic air over central and eastern Asia, resulting in persistent cold spells. Blocking near Greenland related to low-level temperature anomalies led to northerly flow into eastern North America, inducing persistent cold periods. Potential Arctic connections in Europe are less clear. Variability in the North Pacific can reinforce downstream Arctic changes, and Arctic amplification can accentuate the impact of Pacific variability. The authors emphasize multiple linkage mechanisms that are regional, episodic, and based on amplification of existing jet stream wave patterns, which are the result of a combination of internal variability, lower-tropospheric temperature anomalies, and midlatitude teleconnections. The quantitative impact of Arctic change on midlatitude weather may not be resolved within the foreseeable future, yet new studies of the changing Arctic and subarctic low-frequency dynamics, together with additional Arctic observations, can contribute to improved skill in extended-range forecasts, as planned by the WMO Polar Prediction Project (PPP).

Spatio-Temporal Linkages between Declining Arctic Sea-Ice Extent and Increasing Wildfire Activity in the Western United States

“…ENSO and PDO) examined for the western U.S. Understanding the linkages between Arctic amplification and enhanced meridionality of mid-latitude upper-level atmospheric flow remains uncertain and may express strong regional, seasonal and interannual variability [68]. Here, our findings suggest a broad-scale teleconnective feature related to ASIE that indirectly modulates wildfire activity with evidence that summertime 300-hPa flow is influenced by prior-winter ASIE.…”

Towards the Marine Arctic Component of the Pan-Eurasian Experiment

“…Many of these 5 processes act on a subgrid-scale, and they accordingly need to be parameterized in Earth system models and operational NWP and sea ice models . However, there is also a strong need to better understand synoptic and hemisphericalscale processes (Zhang et al, 2004;Crawford and Serreze, 2016;Overland et al, 2016). From the point of view of MA-PEEX, particularly important processes to be studied are those responsible for the interaction between the marine, atmospheric, and terrestrial components of PEEX.…”

Is the melting Arctic changing midlatitude weather?

“…Other results suggest that if the Arctic does affect severe weather to the south, its influence is regional in extent and episodic, even within seasons. 10 Fortunately, one can look for patterns in the variability itself using what's known as the Arctic oscillation (AO) index to discern correlations with episodes of severe weather. The AO index is a measure of the dominant pattern of sea-level pressure variations north of about 55° N latitude.…”

“…10,12 In the first case, analyses of field observations over the past decade and of simulations suggest a direct linkage between the regional loss of sea ice in the Barents and Kara Seas north of Eurasia during the autumn months and cold, stormy conditions experienced in eastern Asia. The winters were colder during years with negative phases of the AO than during years with positive AO phases.…”