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B1064
Title: Seasonal vine copula model for a glacier in King George island Authors:  Mario Gomez - Universidad Carlos III de Madrid (Spain) [presenting]
Concepcion Ausin - Universidad Carlos III de Madrid (Spain)
Carmen Dominguez - Universidad de Salamanca (Spain)
Abstract: The study of the mass balance in glaciers is vital to understand their future behaviour. One component of this mass balance is the loss of water produced by melting, known as glacier discharge. A vine copula structure is proposed to model the multivariate and nonlinear dependence among the discharge and meteorological variables. The multivariate joint distribution function is defined as a mixture of four components according to the presence or not of positive discharge and/or precipitation. Each mixture component is modelled with a vine copula. The conditional probability of not having discharge, given the meteorological conditions, is obtained from the proposed joint distribution. Moreover, the structure of the vine copula allows us to derive the conditional distribution function of the discharge given the meteorological values. Three different methods are proposed and compared to obtain predictions of the future discharge values based on three expected loss functions. This framework is applied to a large data base provided by the association GLACKMA who have been collecting data since 2002 from a measurement station located in the King George Island (Antarctica). The seasonal effect is considered by using different parameters for each season. We have found that both, the probability of positive discharge and the prediction of the discharge amount obtained with our proposed vine copula model outperforms the standard results of the classical degree-day models.