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Center for Nonlinear Studies |
One of the biggest unanswered questions in evaluating future climate scenarios is, “How much will sea levels rise in the next 50 to 100 years?” Hundreds of millions of people live within a few meters of sea level, and billions depend on infrastructure that is vulnerable to rising seas. Sea level rise has three major contributions: thermal expansion of seawater, melting mountain glaciers and ice caps, and melt from the worlds two large ice sheets in Greenland and Antarctica. Currently, these three factors contribute approximately equally to rising sea level, but in the coming century melt from the ice sheets is expected to become the dominant contributor. Current climate models do not include dynamical ice sheets or their interactions with the atmosphere and ocean, so accurate sea level projections are impossible to make. Our group is one of several groups working to fill this void. In Antarctica, the ice most vulnerable to melting occurs where ice sheets ooze off the continent into the ocean, forming ice shelves, vast expanses of ice hundreds of meters to kilometers thick that float on top of the ocean. Because of its interface with the ocean, this ice is particularly susceptible to accelerated melting as the surrounding ocean warms. How much melting can occur depends on the specific ocean and ice sheet/ice shelf dynamics; climate models play a vital role in exploring these changing dynamics. Matters are complicated by huge disparities in the length scales at which the physics occurs: ice shelves are on the order of kilometers thick and hundreds of kilometers long, yet their melt rates depend sensitively on the physical properties in boundary layers under the ice that range in scale from millimeters to a few meters. This disparity in scales means that the physics of these boundary layer physics cannot be simulated directly, and must be parameterized. In this talk, I explore an analytic ice/ocean boundary layer theory and my own parameterization of this theory within the Parallel Ocean Project, a global ocean model developed at LANL
Host: Peter Loxley, loxley@lanl.gov