HR: 16:15h
AN: C22B-02    [PDF]
TI: The Distributed Application of an Enhanced Temperature-Index Melt Model Including Albedo and Global Radiation
AU: * Pellicciotti, F
EM: pellicciotti@ihw.baug.ethz.ch
AF: Institute of Hydromechanics and Water Resources Management, ETH Zurich, ETH Hoenggerberg, IHW-HIL, Zurich, CH-8093 Switzerland
AU: Brock, B
EM: b.w.brock@dundee.ac.uk
AF: Department of Geography, University of Dundee, Dundee.DD1 4HN, Dundee, DD1 4HN United Kingdom
AU: Strasser, U
EM: u.strasser@iggf.geo.uni-muenchen.de
AF: Department of Earth and Environmental Sciences, University of Munich, Luisenstr. 37, Munich, D-80333 Germany
AU: Corripio, J
EM: Javier.Corripio@meteo.fr
AF: Centre d'Etudes de la Neige, M‚t‚o France - CNRM, 1441, Rue de la Piscine, St. Martin d'Heres, F - 38406 France
AU: Burlando, P
EM: paolo.burlando@ethz.ch
AF: Institute of Hydromechanics and Water Resources Management, ETH Zurich, ETH Hoenggerberg, IHW-HIL, Zurich, CH-8093 Switzerland
AU: Funk, M
AF: Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zurich, ETH-Zentrum, Zurich, CH-8092 Switzerland
AB: An enhanced temperature-index (ETI) melt model is presented, in which the classical dependency on temperature is extended by considering global radiation and albedo. An additive form of the temperature index (TI) model is proposed, aiming at clearly separating the two important contributions to melt energy, namely the longwave radiation and turbulent fluxes in one term and the shortwave radiation in the other. The ETI model is a significant improvement over other formulations of the temperature-index method. This was shown by comparing melt rates computed by the temperature index based models with calculations obtained using a physically based energy balance model at five sites on Haut Glacier d'Arolla, Switzerland. Data were provided by five automatic weather stations located along two intersecting transects in 2001. The results show that the ETI model is capable of accounting for about 90% of the surface melt rate variation at all the stations tested. This is due, on one hand, to the fact that including albedo enables the model to capture the major increases in the surface melt rate due to snow metamorphism and the transition from snow to ice. On the other hand, the more physically-based melt process representation of the ETI model reduces the over-sensitivity to temperature fluctuations which is typical of simpler formulations of the TI approach. Once tested at the point scale, where the availability of high quality input data allowed to evaluate the model performance independently from errors introduced by parameterisations of the meteorological input data, the ETI model was applied in a distributed manner over the entire glacier. The paper discusses the distributed application of the ETI model and the differences in model performance from the point to the distributed scale, and highlights the robustness of the model when different extrapolation schemes for the redistribution of the input variables, namely temperature, albedo and global radiation, are used. In particular, a way of accounting for cloud cover in the parametric model used to compute global radiation is presented.
DE: 1800 HYDROLOGY
DE: 1827 Glaciology (1863)
DE: 1863 Snow and ice (1827)
SC: Cryosphere [C]
MN: 2003 Fall Meeting