Extended Abstract (116K)9.2
On the relative contributions of dynamic and thermodynamic forcing of sea ice concentration anomalies in the Southern Beaufort Sea inferred through spatiotemporal statistical analysis.
Jennifer Verlaine Lukovich, University of Manitoba, Winnipeg, MB, Canada; and D. G. Barber
Previous sea ice studies have demonstrated a reduction in sea ice areal extent and thickness. While this behaviour is thought to be a signature of sea ice response to global climate variability and change, it is also directly attributable to sea ice response to dynamic and thermodynamic atmospheric and oceanic forcing mechanisms. Recent sea ice studies of the Southern Beaufort Sea (SBS) for the Canadian Arctic Shelf Exchange Study (CASES) have shown a correspondence between positive sea-ice concentration anomalies and atmospheric forcings. Previous studies of ice reduction in the Beaufort Sea have also illustrated the role of atmospheric circulation in sea-ice behaviour associated with the weakening of the Beaufort gyre, manifested in the coexistence of SLP high and low regions in the Canadian Arctic in the late summer/early Fall. The present study examines this correspondence through the investigation of spatiotemporal autocorrelations for the total sea ice concentration (SIC) anomalies in the SBS, as well as for atmospheric parameters during the onset of ice formation. Thermodynamic processes are examined through the evaluation of timescales associated with the atmospheric parameter of surface air temperature (SAT). Dynamic processes are examined through the evaluation of timescales associated with the atmospheric parameters of sea level pressure (SLP), in addition to zonal and meridional winds and their gradients. Moreover, the Weiss criterion, which monitors strain- and relative vorticity-dominated regions, is also used to evaluate the influence of shear and cyclonic, namely dynamical, effects associated with the Beaufort gyre on SIC anomaly behaviour.
Analyses of e-folding times show that SIC anomalies are characterized on average by a 4 – 7 week timescale to the west of Banks Island, and emphasize the dominant role of atmospheric dynamical forcing mechanisms in driving SIC behaviour. The results from this investigation further suggest a correspondence between strain, a predominance in upwelling-favourable winds and the 4 – 7 week timescale in SIC anomalies. The implications of these findings for understanding thermodynamic and dynamic atmospheric and oceanic processes responsible for SIC anomaly patterns in the SBS will also be discussed.
Session 9, The Cryosphere - Sea Ice Motion, Thickness and Properties
Wednesday, 12 January 2005, 4:00 PM-5:30 PM
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