Abstract
Abstract. To investigate ice sheet evolution over the timescale of a glacial cycle, 3-D ice sheet models (ISMs) are typically run at "coarse" grid resolutions (10–50 km) that do not resolve individual mountains. This will introduce to-date unquantified errors in sub-grid (SG) transport, accumulation and ablation for regions of rough topography. In the past, synthetic hypsometric curves, a statistical summary of the topography, have been used in ISMs to describe the variability of these processes. However, there has yet to be detailed uncertainty analysis of this approach. We develop a new flow line SG model for embedding in coarse resolution models. A 1 km resolution digital elevation model was used to compute the local hypsometric curve for each coarse grid (CG) cell and to determine local parameters to represent the hypsometric bins' slopes and widths. The 1-D mass transport for the SG model is computed with the shallow ice approximation. We test this model against simulations from the 3-D Ice Sheet System Model (ISSM) run at 1 km grid resolution. Results show that none of the alternative parameterizations explored were able to adequately capture SG surface mass balance and flux processes. Via glacial cycle ensemble results for North America, we quantify the impact of SG model coupling in an ISM. We show that SG process representation and associated parametric uncertainties, related to the exchange of ice between the SG and CG cells, can have significant (up to 35 m eustatic sea level equivalent for the North American ice complex) impact on modelled ice sheet evolution.
Funder
Natural Sciences and Engineering Research Council of Canada
Reference39 articles.
1. Abe-Ouchi, A. and Blatter, H.: On the initiation of ice sheets, Ann. Glaciol., 18, 203–203, 1993.
2. Abe-Ouchi, A., Saito, F., Kawamura, K., Raymo, M. E., Okuno, J., Takahashi, K., and Blatter, H.: Insolation-driven 100,000-year glacial cycles and hysteresis of ice-sheet volume, Nature, 500, 190–193, 2013.
3. BODC: British oceanographic data centre, The GEBCO_08 Grid, version 20091120, available at: http://www.gebco.net (last access: 6 October 2013), 2010.
4. Budd, W. F. and Smith, I.: The growth and retreat of ice sheets in response to orbital radiation changes, Sea Level, Ice, and Climatic Change, 369–409, 1981.
5. Clarke, G. K.: Fast glacier flow: ice streams, surging, and tidewater glaciers, J. Geophys. Res.-Sol. Ea., 92, 8835–8841, 1987.
Cited by
8 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献