Viruses in Antarctic ecosystems

first_imgThis review seeks to highlight the potential importance of viruses in Antarctic ecosystems and describe the limited scope of Antarctic virus studies to date, including studies of marine, terrestrial and freshwater communities. Although much of the existing work focuses on the microbial community, there are also studies of virus infection in Antarctic animal and plant populations. We describe methodologies available for the study of viral ecology in the field and in calling for a more intensive research effort discuss how microbial ecology might benefit from the study of viruses in Antarctic ecosystems.last_img

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Initialization of ice-sheet forecasts viewed as an inverse Robin problem

first_imgAs simulations of 21st-century climate start to include components with longer timescales,such as ice sheets, the initial conditions for those components will become critical to the forecast.This paper describes an algorithm for specifying the initial state of an ice-sheet model, given spatiallycontinuous observations of the surface elevation, the velocity at the surface and the thickness of theice. The algorithm can be viewed as an inverse procedure to solve for the viscosity or the basal dragcoefficient. It applies to incompressible Stokes flow over an impenetrable boundary, and is based upontechniques used in electric impedance tomography; in particular, the minimization of a type of costfunction proposed by Kohn and Vogelius. The algorithm can be implemented numerically using only theforward solution of the Stokes equations, with no need to develop a separate adjoint model. The onlyrequirement placed upon the numerical Stokes solver is that boundary conditions of Dirichlet, Neumannand Robin types can be implemented. As an illustrative example, the algorithm is applied to shear flowdown an impenetrable inclined plane. A fully three-dimensional test case using a commercially availablesolver for the Stokes equations is also presented.last_img read more

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