Air‐sea interactions during an Arctic storm

Abstract

[1] The impacts of increased open water in the Beaufort Sea were investigated for a summer Arctic storm in 2008 using a coupled atmosphere-ice-ocean model. The storm originated in northern Siberia and slowly moved into the Beaufort Sea along the ice edge in late July. The maximum wind associated with the storm occurred when it was located over the open water near the Beaufort Sea coast, after it had moved over the Chukchi and Beaufort Seas. The coupled model system is shown to simulate the storm track, intensity, maximum wind speed and the ice cover well. The model simulations suggest that the lack of ice cover in the Beaufort Sea during the 2008 storm results in increased local surface wind and surface air temperature, compared to enhanced ice cover extents such as occurred in past decades. In addition, due to this increase of open water, the surface latent and sensible heat fluxes into the atmosphere are significantly increased. However, there were no significant impacts on the storm track. The expanded open water and the loss of the sea ice results in increases in the surface air temperature by as much as 8 C. Although the atmospheric warming mostly occurs in the boundary layer, there is increased atmospheric boundary turbulence and downward kinetic energy transport that reach to mid-levels of the troposphere and beyond. These changes result in enhanced surface winds, by as much as $4 m/s during the 2008 storm, compared to higher ice concentration conditions (typical of past decades). The dominant sea surface temperature response to the storm occurs over open water; storm-generated mixing in the upper ocean results in sea surface cooling of up to 2 C along the southern Beaufort Sea coastal waters. The Ekman divergence associated with the storm caused a decrease in the fresh water content in the central Beaufort Sea by about 11 cm.

Simulated Arctic atmospheric feedbacks associated with late summer sea ice anomalies

“…Loss of sea ice in region 4 (Beaufort Sea) results in a regional significant near‐surface temperature increase of up to 6 K. A similar impact of increased open water in the Beaufort Sea was discussed by Long and Perrie [] who applied a coupled atmosphere‐ice‐ocean model to simulating a summer storm in 2008. Consistent with Long and Perrie, our simulated circulation changes indicate the presence of baroclinic processes in the atmospheric response over the Western Arctic.…”

On the Increasing Importance of Air-Sea Exchanges in a Thawing Arctic: A Review

“…In 2012, sea ice loss occurred later in the season and at higher latitudes; the exposed ocean saw a smaller net surface radiative flux for a shorter time and warmed less [152]. Seasonality of ocean temperatures is also influenced by the Pacific Decadal Oscillation (PDO) and the co-location of Arctic storm tracks and sea ice cover [39,178,233,234]. On decadal time scales, Pacific and Atlantic inter-decadal variability was linked to rapid early 20th-century Arctic warming though interactions with SST anomalies and the atmospheric circulation [235].…”

“…Increased turbulent fluxes can decrease vertical static stability, particularly in winter, [44,47,[196][197][198][199][200][201][202] and generate a local geopotential height anomaly near the warming [21] helping to sustain the anomalous surface turbulent fluxes [52]. Regional diabatic heating or cooling influences surface baroclinicity and cyclone activity [176,178,203]. A significant surface turbulent flux perturbation can generate an anomalous Rossby wave train causing a global temperature and zonal wind response [204], the characteristics of which depend on the location of the heating anomaly [205,206].…”

“…For example, low-level jets in the Arctic enhance turbulent fluxes through increased wind speeds and are commonly associated with synoptic-scale baroclinicity over ice-free seas, strong gradients in topography, and the sea ice edge [172]. Synoptic-scale cyclone activity dominates the Arctic atmospheric circulation on short spatial and temporal scales [173][174][175] driving strong SH and LH fluxes [176][177][178]. Variability of the Arctic atmospheric circulation on monthly and seasonal time scales is characterized by preferred patterns of variability termed low-frequency modes: the Arctic Oscillation (AO)/Northern Annular Mode (NAM) [179], North Atlantic Oscillation (NAO), Arctic Dipole (AD) [180], and Pacific-North American Pattern (PNA) [181].…”

Northern Hemisphere storminess in the Norwegian Earth System Model (NorESM1-M)

“…Inputs in the later stages of the cyclone life cycle showed little impact. Furthermore, two case studies of Arctic cyclones found that increased surface energy fluxes in the later stages of the cyclone were not enough to overcome the large-scale dynamics (Long and Perrie, 2012;Simmonds and Rudeva, 2012). However, the former study indicated increased maximum wind speeds as the cyclone studied moved over open water, primarily through enhanced momentum exchange between the surface and atmosphere compared to what would occur over sea ice.…”