| Title | How ice shelf morphology controls basal melting |
| Author | Little, C.M.; Gnanadesikan, A.; Oppenheimer, M. |
| Author Affil | Little, C.M., Princeton University, Department of Geophysics, Princeton, NJ. Other: NOAA, Geophysical Fluid Dynamics Laboratory |
| Source | Journal of Geophysical Research, 114(C12), Citation C12007. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0148- 0227 |
| Publication Date | 2009 |
| Notes | In English. 57 refs. GeoRef Acc. No: 297316. CRREL Acc. No: 64002412 |
| Index Terms | glacial geology; heat flux; ice; ice shelves; melting; salinity; temperature; Antarctica--Amundsen Sea; Southern Ocean-- Bellingshausen Sea; Amundsen Sea; Antarctica; bathymetry; Bellingshausen Sea; climate effects; continental shelf; continental slope; mixing; numerical models; ocean circulation; rates; sea ice; sea-surface temperature; Southern Ocean |
| Abstract | The response of ice shelf basal melting to climate is a function of ocean temperature, circulation, and mixing in the open ocean and the coupling of this external forcing to the sub-ice shelf circulation. Because slope strongly influences the properties of buoyancy-driven flow near the ice shelf base, ice shelf morphology plays a critical role in linking external, subsurface heat sources to the ice. In this paper, the slope-driven dynamic control of local and area-integrated melting rates is examined under a wide range of ocean temperatures and ice shelf shapes, with an emphasis on smaller, steeper ice shelves. A 3-D numerical ocean model is used to simulate the circulation underneath five idealized ice shelves, forced with subsurface ocean temperatures ranging from -2.0°C to 1.5°C. In the sub-ice shelf mixed layer, three spatially distinct dynamic regimes are present. Entrainment of heat occurs predominately under deeper sections of the ice shelf; local and area-integrated melting rates are most sensitive to changes in slope in this "initiation" region. Some entrained heat is advected upslope and used to melt ice in the "maintenance" region; however, flow convergence in the "outflow" region limits heat loss in flatter portions of the ice shelf. Heat flux to the ice exhibits (1) a spatially nonuniform, superlinear dependence on slope and (2) a shape- and temperature- dependent, internally controlled efficiency. Because the efficiency of heat flux through the mixed layer decreases with increasing ocean temperature, numerical simulations diverge from a simple quadratic scaling law. |
| URL | http://hdl.handle.net/10.1029/2008JC005197 |
| Publication Type | journal article |
| Record ID | 87517 |