HR: 0800h
AN: C41C-0208    [Abstracts]
TI: A Contribution to the Sea-Ice Model Intercomparison Project 2 (SIMIP2) Thermodynamic Sea-Ice Models Assessment : Impact of Vertical Resolution, Vertical Salinity Profile, and Salinity- and Temperature-Dependent Thermal Properties
AU: Fichefet, T
EM: fichefet@astr.ucl.ac.be
AF: Institut d'Astronomie et de G\'eophysique G. Lema\^itre, Universit\'e Catholique de Louvain, Chemin du cyclotron, 2, Louvain-la-Neuve, 1348 Belgium
AU: * Vancoppenolle, M
EM: vancop@astr.ucl.ac.be
AF: Institut d'Astronomie et de G\'eophysique G. Lema\^itre, Universit\'e Catholique de Louvain, Chemin du cyclotron, 2, Louvain-la-Neuve, 1348 Belgium
AB: Results from a sophisticated thermodynamic sea-ice model are presented. The model has the following peculiarities. First, the sea-ice pack is represented by several layers of snow on top of several layers of ice, and different ways of specifying the number and thickness of vertical layers are possible. Second, the heat-diffusion equation and its boundary conditions explicitly take into account the thermal damping effect of the brine pockets trapped into the ice through temperature- and salinity-dependent thermal properties, but density is nevertheless a constant. The main experiment consists in an almost-one-year integration of the model following the SIMIP2 (Sea-Ice Model Intercomparision Project) specifications, i.e., a Lagrangian multiyear undeformed ice floe forced by observed hourly atmospheric and monthly oceanic data fields. Model results are compared to weekly observations of ice and snow thicknesses. Snow precipitations have to be increased by 50% for the snow thickness to be correctly reproduced, supporting gauge problems already reported in the past. Ice thickness shows good overall agreement, especially in winter, and an underestimation of around 10 cm of surface melting in summer. Sensitivity experiments show that the effect of salinity and temperature through thermal properties is significant. The non-linear vertical salinity profile can be replaced by a linear profile with same mean salinity. Finally, the simplest resolution which conserves the main features of the results gathers one layer in the snow and between 5 and 10 layers in the ice.
DE: 4207 Arctic and Antarctic oceanography
DE: 4255 Numerical modeling
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting