2006 Annual Meeting and Arctic Forum | Abstracts

Downscaling Characteristics of Sea Ice and Ocean Circulation in the Beaufort-Chukchi Seas Simulated by an IARC Coupled Ice-Ocean Model (CIOM)

Jia Wang¹, Haohuo Hu², Kohei Mizobata³, Meibing Jin^4
1International Arctic Research center, University of Alaska Fairbanks, 930 Koyukuk Drive, Fairbanks, AK, 99775, USA, Phone 907-474-2685, Fax 907-474-2643, jwang@iarc.uaf.edu
²no contact info
³Graduate School of Fisheries Science, Hokkaido University, 3-1-1 Minato-cho, Hakodate, Hokkaido, 041-8611, Japan, Phone +81 138 40 5618, mizobata@salmon.fish.hokudai.ac.jp
⁴International Arctic Research Center, University of Alaska Fairbanks, PO Box 757340, Fairbanks, AK, 99775-7340, USA, Phone 907-474-2442, Fax 907-474-2643, mjin@iarc.uaf.edu

We applied an IARC regional CIOM (Coupled Ice-Ocean Model, Wang et al. 2002, 2005) based on POM to simulate the downscaling ice and ocean processes with a 4-km resolution. The Beaufort CIOM was nested to the CCSR/NIES/FRCGC high-resolution (1/6 x 1/4 degrees) global coupled atmosphere-sea ice-ocean model. Atmospheric forcing data were derived from the NCEP reanalysis. Simulation of seasonal cycle was conducted. In the Chukchi Sea, the Bering inflow separates into three branches: the first main branch flows along the Alaska’s coast that is the Alaska Coastal Current (ACC); the second branch flows northward and turns to the right, joining the ACC along the Beaufort coast; and the third branch flows toward the Northwind Ridge. The Beaufort Gyre is well reproduced, superimposed by numerous mesoscale eddies, with anticyclones outnumbering cyclones. We also investigated downscaling sea ice dynamics, such as sea ice ridging, rafting, leads and landfast ice, which are not resolved in the previous coarse resolution model (Wang et al. 2002, 2005). This approach combining the global model for the 20th century climate simulation with the regional downscaling/nesting simulation helps understanding of both large-scale sea ice variability and small-scale sea ice dynamics. Sea ice breaks up offshore piece by piece with landfast ice untouched along the Beaufort Sea coast. Sea ice cracks from pack ice with irregular shapes due to 1) complex ocean circulation, coastal current, and mesoscale eddies, 2) multi-category sea ice dynamics, and 3) complex and high-resolution geometry and topography. Sea ice ridging, rafting, and openings/leads can be well reproduced in sea ice thickness and concentration. Model validation using in situ observations, satellite measurements, and historical datasets is underway.

Wang, J., Q. Liu and M. Jin, 2002. A User’s Guide for a Coupled Ice-Ocean Model (CIOM)
in the Pan-Arctic and North Atlantic Oceans. International Arctic Research Center-
Frontier Research System for Global Change, Tech. Rep. 02-01, 65 pp.
Wang, J., Q. Liu, M. Jin, M. Ikeda and F.J. Saucier, 2005. A coupled ice-ocean model in
the pan-Arctic and the northern North Atlantic Ocean: Simulation of seasonal cycles.
J. Oceanogr., 61, 213-233.