Abstract
The recent sea-ice reduction in the Arctic Ocean is not spatially uniform, but is disproportionally large around the Northwind Ridge and Chukchi Plateau compared to elsewhere in the Canada Basin. In the Northwind Ridge region, Pacific Summer Water (PSW) delivered from the Bering Sea occupies the subsurface layer. The spatial distribution of warm PSW shows a quite similar pattern to the recent ice retreat, suggesting the influence of PSW on the sea-ice reduction. To understand the regionality of the recent ice retreat, we examine the dynamics and timing of the delivery of the PSW into this region. Here, we adopt a two-layer linearized potential vorticity equation to investigate the behavior of Rossby waves in the presence of a topographic discontinuity in the high latitude ocean. The analytical results show a quite different structure from those of mid-latitude basins due to the small value of β. Incident barotropic waves excited by the sea-ice motion with large annual variation can be scattered into both barotropic and baroclinic modes at the discontinuity. Since the scattered baroclinic Rossby wave with annual frequency cannot propagate freely, a strong baroclinic current near the topographic discontinuity is established. The seasonal variation of current near the topographic discontinuity would cause a kind of selective switching system for shelf water transport into the basin. In our simple analytical model, the enhanced northward transport of summer water and reduced northward transport of winter water are well demonstrated. The present study indicates that these basic dynamics imply that a strengthening of the surface forcing during winter in the Canada Basin could cause sea-ice reduction in the Western Arctic through the changes of underlying Pacific Summer Water.
Similar content being viewed by others
References
Maslanik, J. A., M. C. Serreze and T. Agnew (1999): On the record reduction in 1998 Western Arctic sea-ice cover. Geophys. Res. Lett., 26(13), 1905–1908.
Owen, G. W., I. D. Abrahams, A. J. Willmott and C. W. Hughes (2002): On the scattering of baroclinic Rossby waves by a ridge in a continuously stratified ocean. J. Fluid Mech., 465, 131–155.
Pedlosky, J. (1987): Geophysical Fluid Dynamics. Springer, New York, 710 pp.
Proshutinsky, A., M. Steele, J. Zhang, G. Holloway, N. Steiner, S. Hakkinen, D. M. Holland, R. Gerdes, C. Koeberle, M. Karcher, M. Johnson, W. Maslowski, W. Walczowski, W. Hibler and J. Wang (2001): Multinational effort studies differences among Arctic Ocean models. EOS, 82(51), 637–644.
Schmidt, G. A. and E. R. Johnson (1997): The scattering of stratified topographic Rossby waves by seafloor ridges. Geophys. Astrophys. Fluid Dyn., 84, 29–52.
Shimada, K., K. Hatakeyama, T. Nakamura, N. Koyama, R. Krishfield, S. Honjo and T. Takizawa (1997): On the ocean circulation in the Canada Basin of the Arctic Ocean. JAMSTECR, 36, 207–218.
Shimada, K., E. C. Carmack, K. Hatakeyama and T. Takizawa (2001): Varieties of shallow temperature maximum waters in the Western Canadian Basin of the Arctic Ocean. Geophys. Res. Lett., 28(18) 3441–3444.
Shimada, K., M. Itoh, S. Nishino, F. McLaughlin, E. Carmack and A. Proshutinsky (2005): Halocline structure in the Canada Basin of the Arctic Ocean. Geophys. Res. Lett., 32, L03605, doi:10.1029/2004GL021358.
Shimada, K., T. Kamoshida, M. Itoh, S. Nishino, E. Carmack, F. McLaughlin, S. Zimmermann and A. Proshutinsky (2006): Pacific Ocean inflow: Influence on catastrophic reduction of sea ice cover in the Arctic Ocean. Geophys. Res. Lett., 33, L08605, doi:10.1029/2005GL025624.
Shimada, Y. (2006): Model study of seasonal variation of western boundary currents over a continental slope: Application to the East Sakhalin Currents. Ph.D. thesis of Environmental Earth Science, Graduate School of Hokkaido University.
Wang, L. and C. J. Koblinsky (1994): Influence of mid-ocean ridges on Rossby waves. J. Geophys. Res., 99(C12), 25143–25153.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Sumata, H., Shimada, K. Northward transport of pacific summer water along the Northwind Ridge in the Western Arctic Ocean. J Oceanogr 63, 363–378 (2007). https://doi.org/10.1007/s10872-007-0035-4
Received:
Revised:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/s10872-007-0035-4