Improved parameterization of marine ice dynamics and flow instabilities for simulation of the Austfonna ice cap using a large-scale ice sheet model Title,Eos Trans.

Dunse, Thorben; Greve, Ralf; Schuler, Thomas V.; Hagen, Jon Ove; Navarro Valero, Francisco Jose; Vasilenko, Evgeniy y Reijmer, Carleen (2009). Improved parameterization of marine ice dynamics and flow instabilities for simulation of the Austfonna ice cap using a large-scale ice sheet model Title,Eos Trans.. En: "American Geophysical Union, Fall Meeting 2009", 14/12/2009 - 18/12/2009, San Francisco, California, EEUU.

Descripción

Título: Improved parameterization of marine ice dynamics and flow instabilities for simulation of the Austfonna ice cap using a large-scale ice sheet model Title,Eos Trans.
Autor/es:
  • Dunse, Thorben
  • Greve, Ralf
  • Schuler, Thomas V.
  • Hagen, Jon Ove
  • Navarro Valero, Francisco Jose
  • Vasilenko, Evgeniy
  • Reijmer, Carleen
Tipo de Documento: Ponencia en Congreso o Jornada (Póster)
Título del Evento: American Geophysical Union, Fall Meeting 2009
Fechas del Evento: 14/12/2009 - 18/12/2009
Lugar del Evento: San Francisco, California, EEUU
Título del Libro: Proceedings of American Geophysical Union, Fall Meeting 2009
Fecha: Diciembre 2009
Materias:
Escuela: E.T.S.I. Telecomunicación (UPM)
Departamento: Matemática Aplicada a las Tecnologías de la Información [hasta 2014]
Licencias Creative Commons: Reconocimiento - Sin obra derivada - No comercial

Texto completo

[img]
Vista Previa
PDF (Document Portable Format) - Se necesita un visor de ficheros PDF, como GSview, Xpdf o Adobe Acrobat Reader
Descargar (3MB) | Vista Previa

Resumen

The Austfonna ice cap covers an area of 8120 km2 and is by far the largest glacier on Svalbard. Almost 30% of the entire area is grounded below sea-level, while the figure is as large as 57% for the known surge-type basins in particular. Marine ice dynamics, as well as flow instabilities presumably control flow regime, form and evolution of Austfonna. These issues are our focus in numerical simulations of the ice cap. We employ the thermodynamic, large-scale ice sheet model SICOPOLIS (http://sicopolis.greveweb.net/) which is based on the shallow-ice approximation. We present improved parameterizations of (a) the marine extent and calving and (b) processes that may initiate flow instabilities such as switches from cold to temperate basal conditions, surface steepening and hence, increases in driving stress, enhanced sliding or deformation of unconsolidated marine sediments and diminishing ice thicknesses towards flotation thickness. Space-borne interferometric snapshots of Austfonna revealed a velocity structure of a slow moving polar ice cap (menos que 10m/a) interrupted by distinct fast flow units with velocities in excess of 100m/a. However, observations of flow variability are scarce. In spring 2008, we established a series of stakes along the centrelines of two fast-flowing units. Repeated DGPS and continuous GPS measurements of the stake positions give insight in the temporal flow variability of these units and provide constrains to the modeled surface velocity field. Austfonna¿s thermal structure is described as polythermal. However, direct measurements of the temperature distribution is available only from one single borehole at the summit area. The vertical temperature profile shows that the bulk of the 567m thick ice column is cold, only underlain by a thin temperate basal layer of approximately 20m. To acquire a spatially extended picture of the thermal structure (and bed topography), we used low-frequency (20 MHz) GPR profiling across the ice cap and the particular flow units. The measurements indicate that the gross volume of Austfonna is cold. This observation is supported by model results which suggest that regional fast flow occurs despite the lack of considerable temperate-ice volumes. This in turn indicates that fast flow is accomplished exclusively by basal motion in regions where the glacier base is at pressure-melting conditions, and not by enhanced deformation of considerable volumes of temperate ice.

Más información

ID de Registro: 5616
Identificador DC: http://oa.upm.es/5616/
Identificador OAI: oai:oa.upm.es:5616
URL Oficial: http://www.agu.org/meetings/fm09/
Depositado por: Memoria Investigacion
Depositado el: 10 Ene 2011 10:19
Ultima Modificación: 20 Abr 2016 14:23
  • Open Access
  • Open Access
  • Sherpa-Romeo
    Compruebe si la revista anglosajona en la que ha publicado un artículo permite también su publicación en abierto.
  • Dulcinea
    Compruebe si la revista española en la que ha publicado un artículo permite también su publicación en abierto.
  • Recolecta
  • e-ciencia
  • Observatorio I+D+i UPM
  • OpenCourseWare UPM