Exploring the ingredients required to successfully model the placement, generation, and evolution of ice streams in the British-Irish Ice Sheet

Ice stream evolution is a major uncertainty in projections of the future of the Greenland and Antarctic Ice sheets. Accurate simulation of ice stream evolution requires an understanding of a number of “ingredients” that control the location and behaviour of ice stream flow. Here, we test the influence of geothermal heat flux, grid resolution, and bed hydrology on simulated ice streaming. The palaeo-record provides snapshots of ice stream evolution, with a particularly well constrained ice sheet being the British-Irish Ice Sheet (BIIS). We implement a new basal sliding scheme coupled with thermo-mechanics into the BISICLES ice sheet model, to simulate the evolution of the BIIS ice streams. We find that the simulated location and spacing of ice streams matches well with the empirical reconstructions of ice stream flow in terms of position and direction when simple bed hydrology is included. We show that the new basal sliding scheme allows the accurate simulation for the majority of BIIS ice streams. The extensive empirical record of the BIIS has allowed the testing of model inputs, and has helped demonstrate the skill of the ice sheet model in simulating the evolution of the location, spacing, and migration of ice streams through millennia. Simulated ice streams also prompt new empirical mapping of features indicative of streaming in the North Channel region. Ice sheet model development has allowed accurate simulation of the palaeo record, and allows for improved modelling of future ice stream behaviour

Rejection-Inversion to Generate Variates from Monotone Discrete Distributions

For discrete distributions a variant of rejection from a continuous hat function is presented. The main advantage of the new method, called rejection-inversion, is that no extra uniform random number to decide between acceptance and rejection is required which means that the expected number of uniform variates required is halved. Using rejection-inversion and a squeeze, a simple universal method for a large class of monotone discrete distributions is developed. It can be used to generate variates from the tails of most standard discrete distributions. Rejection-inversion applied to the Zipf (or zeta) distribution results in algorithms that are short and simple and at least twice as fast as the fastest methods suggested in the literature. (author's abstract)Series: Preprint Series / Department of Applied Statistics and Data Processin

D&B v1.0

<p>Terrestrial Biosphere Model.</p> <p>Developer Team:</p> <ol> <li> <p>Marko Scholze, Lund University, Department of Physical Geography and Ecosystem Science, Lund University, Sölvegaten 12, SE-223 62 Lund</p> </li> <li> <p>Finnish Meteorological Institute, Erik Palménin aukio 1; FI-00560 Helsinki, Finland</p> </li> <li> <p>THE UNIVERSITY COURT OF THE UNIVERSITY OF EDINBURGH, a charitable body registered in Scotland under registration number SC005336; incorporated under the Universities (Scotland) Acts and having its principal office at Old College, South Bridge, Edinburgh EH8 9YL</p> </li> <li> <p>The Inversion Lab - Thomas Kaminski Consulting, Tewessteg 4, D-20249 Hamburg,</p> </li> <li> <p>Max Planck Society, represented by the Max Planck Institute for Biogeochemistry, Research Organisation (eingetragener Verein: registered association)</p> </li> <li> <p>University of Reading, Whiteknights, Reading, Berkshire RG6 6AH, United Kingdom</p> </li> </ol&gt

Manual de procedimientos.

Biblioteca tiene 1 ej