Major cause of unprecedented Arctic warming in January 2016: Critical role of an Atlantic windstorm

Abstract

In January 2016, the Arctic experienced an extremely anomalous warming event after an extraordinary increase in air temperature at the end of 2015. During this event, a strong intrusion of warm and moist air and an increase in downward longwave radiation, as well as a loss of sea ice in the Barents and Kara seas, were observed. Observational analyses revealed that the abrupt warming was triggered by the entry of a strong Atlantic windstorm into the Arctic in late December 2015, which brought enormous moist and warm air masses to the Arctic. Although the storm terminated at the eastern coast of Greenland in late December, it was followed by a prolonged blocking period in early 2016 that sustained the extreme Arctic warming. Numerical experiments indicate that the warming effect of sea ice loss and associated upward turbulent heat fluxes are relatively minor in this event. This result suggests the importance of the synoptically driven warm and moist air intrusion into the Arctic as a primary contributing factor of this extreme Arctic warming event.

Atmospheric River Impacts on Greenland Ice Sheet Surface Mass Balance

“…In most cases, ARs are understood to form as part of the process of air mass convergence and advection in the warm sector of extratropical cyclones—according to the American Meteorological Society glossary, ARs are “typically associated with a low‐level jet stream ahead of the cold front of an extratropical cyclone” (American Meteorological Society, ). Moreover, previous studies have linked both atmospheric blocking development and instances of extreme moisture transport into the Arctic to Rossby wave breaking events (Barnes & Hartmann, ; Kim et al, ; Liu & Barnes, ), suggesting that blocking and AR events may be instigated by similar atmospheric dynamics. Liu and Barnes () showed that extreme moisture transport in the Labrador Sea/Baffin Bay region along the southwest coast of Greenland (resembling the moist SOM nodes and western Greenland AR events described in the present work) is favored by cyclonic Rossby wave breaking in the North Atlantic jet stream, while anticyclonic wave breaking more often results in extreme moisture transport off the eastern coast of Greenland toward Iceland and the Nordic Seas.…”

Vertical thermodynamic structure of the troposphere during the Norwegian young sea ICE expedition (N‐ICE2015)

“…Generally, studies of Arctic storms show that the most insight is gained from multiinstrument approaches using in situ data, satellite observations and reanalysis [ Persson et al , ]. However, most synoptic cyclones are not observed in situ [ Kim et al , ]. This makes the complete meteorological observations obtained during the N‐ICE2015 expedition [ Graham et al , ; Cohen et al , ; Walden et al , ], including cloud data and surface radiation especially valuable.…”

“…For example, the sudden drop in ABL height and the change from neutral to unstable static stability during storm M2, coincides with the change in wind direction and passage of the cold front (Figures and ). Overall, the largest impact on tropospheric stability during the N‐ICE2015 winter was due to cyclonic events, similar to the findings of Kim et al [] for winter 2016 in this region.…”

Contribution of Atmospheric Advection to the Amplified Winter Warming in the Arctic North Atlantic Region

“…Sources of increasing atmospheric water vapor are either local evaporation mostly over the ice-free ocean [14] or stronger moisture advection from lower latitudes [15][16][17]. Synopticscale intrusions of warm and moist air masses into the Arctic appear as extreme events related to blocking situations of the large scale circulation [18,19]. Overall, changes in the atmospheric circulation can accelerate Arctic warming by an advective contribution [19][20][21].…”

“…Synopticscale intrusions of warm and moist air masses into the Arctic appear as extreme events related to blocking situations of the large scale circulation [18,19]. Overall, changes in the atmospheric circulation can accelerate Arctic warming by an advective contribution [19][20][21]. Here, we quantify to what extent the most recent winter warming found in the Svalbard region, which is the region of the strongest Arctic winter warming, can be attributed to a shift in atmospheric circulation that facilitates the advection of anomalously warm air masses from the lower latitude Atlantic region.…”