Decadal variability and a recent amplification of the summer Beaufort Sea High

Abstract

[1] The Beaufort Sea High (BSH), an anti-cyclone over the Beaufort Sea, is an important feature of the summer atmospheric circulation over the Arctic Ocean. For example, years characterized by low Arctic sea ice extent are typically associated with the presence of a stronger BSH; with the opposite occurring during years with high sea ice extent. In this paper, we show that there exists variability on the decadal time scale in the intensity and location of the summer BSH. We also show that there has been a trend towards a stronger summer BSH that began in the late 1990s. This trend is shown to be coincident with a tendency towards a reduction in cyclogenesis during the summer over the Beaufort Sea. We argue that that these trends are the result of a warming of the troposphere in the western Arctic and the concomitant reduction in baroclincity.

Recent Declines in Warming and Vegetation Greening Trends over Pan-Arctic Tundra

“…A strengthening of the Beaufort High during summer has been documented [72] along with stronger onshore winds in northern Alaska [73]. The reduced slp over Eurasia is consistent with the strengthening of the positive phase of the Arctic Rapid change Pattern (ARP) that links sea-ice loss to enhanced poleward heat and moisture transport induced by recent shifts in this circulation pattern [74].…”

Drivers and potential predictability of summer time North Atlantic polar front jet variability

“…Recent boreal summers have also been characterized by a changing Arctic atmospheric circulation, with increased anticyclonic flow over the Arctic (Ogi and Wallace 2012) and a more persistent negative Arctic Dipole (Overland et al 2012) associated with increased Greenland blocking and a strengthened Beaufort Sea high pressure region (Moore 2012;Wu et al 2014;Ballinger et al 2014). These have resulted in a southward displacement of the PFJ, leading to cooler wetter summers in Europe, while other areas such as North America have experienced heatwaves and droughts.…”

Interannual variability of the Pacific Water boundary current in the Beaufort Sea

“…The signature of the sum-mer BH is also quite variable from year to year. Using the global NCEP reanalysis fields, Moore (2012) analyzed the signature of the summer (June, July, August) BH from 1948 to the present and found that, while there is a great deal of interannual variability, for most of the record there were no noticeable trends. However, since the mid-1990s a statistically significant positive trend has occurred in the strength of the summer BH.…”

“…Interestingly, there has been an increase in the 13 strength of the summertime Beaufort High in the last decade, (Moore, 2012), while there is still debate as to the interannual variability of the Aleutian Low (McCabe et al, 2001;Mesquita et al, 2010).…”