Summer Arctic Atmospheric Circulation Response to Spring Eurasian Snow Cover and Its Possible Linkage to Accelerated Sea Ice Decrease

Abstract

Anticyclonic circulation has intensified over the Arctic Ocean in summer during recent decades. However, the underlying mechanism is, as yet, not well understood. Here, it is shown that earlier spring Eurasian snowmelt leads to anomalously negative sea level pressure (SLP) over Eurasia and positive SLP over the Arctic, which has strong projection on the negative phase of the northern annular mode (NAM) in summer through the wavemean flow interaction. Specifically, earlier spring snowmelt over Eurasia leads to a warmer land surface, because of reduced surface albedo. The warmed surface amplifies stationary Rossby waves, leading to a deceleration of the subpolar jet. As a consequence, rising motion is enhanced over the land, and compensating subsidence and adiabatic heating occur in the Arctic troposphere, forming the negative NAM. The intensified anticyclonic circulation has played a contributing role in accelerating the sea ice decline observed during the last two decades. The results here provide important information for improving seasonal prediction of summer sea ice cover.

Modulation of Sea Ice Melt Onset and Retreat in the Laptev Sea by the Timing of Snow Retreat in the West Siberian Plain

“…In this way, early snow retreat in the WSP encourages a summer circulation pattern with more ridging over the Kolyma Lowland and East Siberian Sea and troughing over the Taymyr Peninsula and Kara Sea. Impacts on circulation persist through summer and are similar to the findings of Matsumura and Yamazaki () and Matsumura et al (), although their work focused on a larger spatial scale. These relationships could be further tested in a future effort using a coupled atmospheric‐ocean‐ice model.…”

“…This activity then propagates eastward throughout the summer (Matsumura et al, ; Matsumura & Yamazaki, ). Similarly, Matsumura et al () describe how earlier snowmelt over Eurasia enhances rising motion over the land, and compensating subsidence and adiabatic warming in the Arctic troposphere, favoring a negative phase of the summer Arctic Oscillation (AO). This is manifest as positive sea level pressure (SLP) anomalies over the central Arctic Ocean—a pattern conducive to summer sea ice export through Fram Strait (Ogi & Wallace, ).…”

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

“…It is possible that the level of blocking in the Greenland region is an influence both on snow anomalies and the summertime jet or that this feature simply occurred by chance. Matsumura et al (2014) find that early Eurasian snow melt can lead to a negative Arctic Oscillation in summer; although this is an opposite result to that identified here, it supports the possibility of a spring snow cover impact upon summer atmospheric circulation patterns. However, the time and location of snow anomalies is different.…”

“…Barnes 2013;Screen and Simmonds 2013). However, there is also evidence to link earlier Eurasian snowmelt with increased high pressure over the Arctic in summer and a negative annular mode (Matsumura et al 2014).…”

Arctic sea ice and Eurasian climate: A review

“…The negative trend of the NAO has been strongly associated with the surface and tropospheric warming in northeastern Canada and Greenland since 1979, which could potentially have impacted on the variation of the Arctic sea ice. Matsumura et al (2014) revealed that earlier spring snowmelt over Eurasia causes a warmer land surface and therefore amplified stationary Rossby waves, leading to a deceleration of the subpolar jet. As a result, an anomalous anticyclone emerges over the Arctic Ocean.…”