On the scaling laws derived from ice beacon trajectories in the southern Beaufort Sea during the International Polar Year ‐ Circumpolar Flaw Lead study, 2007–2008

摘要

[1] Sea ice motion is an important element in mass balance calculations, ice thermodynamic modeling, ice management plans for industry, and ecosystems studies. In the historical literature, sea ice motion in the Beaufort Sea was characterized by a predominantly anticyclonic motion during winter months, with episodic reversals to cyclonic activity during summer. However, recent studies have shown an increase in cyclonic activity throughout the annual cycle. In this paper we examine circulation in the Beaufort Sea based on the trajectories of 22 ice beacons launched in the Franklin Bay area during the International Polar Year ‐ Circumpolar Flaw Lead (IPY‐CFL) study during an over‐wintering experiment in 2007–2008. Dispersion characteristics of ice motion show that absolute zonal dispersion follows a t~2 scaling law characteristic of advection associated with Beaufort Gyre circulation, whereas absolute meridional dispersion follows a scaling law of t~(5/4) characteristic of floaters and dispersion in 2‐D turbulence. Temporal autocorrelations of ice velocity fluctuations highlight definitive timescales with values of 1.2 (0.7) days in the zonal (meridional) direction. Near‐Gaussian behavior is reflected in higher‐order moments for ice velocity fluctuation probability density functions (pdfs). Non‐Gaussian behavior for absolute displacement pdfs indicates spatial heterogeneity in the ice motion fields. Atmospheric forcing of sea ice is explored through analysis of daily North American Regional Reanalysis and in situ wind data, where it is shown that ice in the CFL study region travels with an average speed of approximately 0.2% and an average angle of 51.5° to the right of the surface winds during the 2007–2008 winter. The results from this analysis further demonstrate seasonality in ice drift to wind ratios and angles that corresponds to stress buoy data indicative of increases in internal ice stress and connectivity due to consolidation of the seasonal ice zone to the coast and perennial ice pack during winter in the Beaufort Sea region.