23 Dec 2021
23 Dec 2021
Status: a revised version of this preprint is currently under review for the journal HESS.

Use of expert elicitation to assign weights to climate and hydrological models in climate impact studies

Eva Sebok1, Hans Jørgen Henriksen1, Ernesto Pastén-Zapata1,2, Peter Berg3, Guillume Thirel4, Anthony Lemoine4, Andrea Lira-Loarca5, Christiana Photiadou3,6, Rafael Pimentel7,8, Paul Royer-Gaspard4, Erik Kjellström3, Jens Hesselbjerg Christensen9,10,11, Jean-Philippe Vidal12, Philippe Lucas-Picher13,14, Markus G. Donat15,16, Giovanni Besio17, María José Polo7,8, Simon Stisen1, Yvan Caballero18, Ilias G. Pechlivanidis3, Lars Troldborg1, and Jens Christian Refsgaard1 Eva Sebok et al.
  • 1Geological Survey of Denmark and Greenland, Copenhagen, Denmark
  • 2University of Eastern Finland, Joensuu, Finland
  • 3Swedish Meteorological and Hydrological Institute, Norrköping, Sweden
  • 4Université Paris-Saclay, INRAE, HYCAR Research Unit, Antony, France
  • 5University of Granada, Granada, Spain
  • 6European Environment Agency, Copenhagen, Denmark
  • 7Fluvial Dynamics and Hydrology Research Group, Andalusian Institute for Earth System Research (IISTA), University of Córdoba, Córdoba, Spain
  • 8Department of Agronomy, Unit of Excellence María de Maeztu (DAUCO), University of Córdoba, Córdoba, Spain
  • 9Physics of Ice, Climate and Earth, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
  • 10NORCE Norwegian Research Centre, The Bjerknes Centre for Climate Research, Bergen, Norway
  • 11Danish Meteorological Institute, Copenhagen, Denmark
  • 12INRAE, UR RiverLy, Villeurbanne Cedex, France
  • 13Groupe de Météorologie de Grande Échelle et Climat, Centre National de Recherches Météorologiques, Météo-France, Toulouse, France
  • 14Département des sciences de la Terre et de l'atmosphère, Université du Québec à Montréal, Montréal, Québec, Canada
  • 15Barcelona Supercomputing Center, Barcelona, Spain
  • 16ICREA, Pg. Lluís Companys 23, Barcelona, Spain
  • 17University of Genoa, Genoa, Italy
  • 18BRGM, Univ. Montpellier, Montpellier, France

Abstract. Various methods are available for assessing uncertainties in climate impact studies. Among such methods, model weighting by expert elicitation is a practical way to provide a weighted ensemble of models for specific real-world impacts. The aim is to decrease the influence of improbable models in the results and easing the decision-making process. In this study both climate and hydrological models are analyzed and the result of a research experiment is presented using model weighting with the participation of 6 climate model experts and 6 hydrological model experts. For the experiment, seven climate models are a-priori selected from a larger Euro-CORDEX ensemble of climate models and three different hydrological models are chosen for each of the three European river basins. The model weighting is based on qualitative evaluation by the experts for each of the selected models based on a training material that describes the overall model structure and literature about climate models and the performance of hydrological models for the present period. The expert elicitation process follows a three-stage approach, with two individual elicitations of probabilities and a final group consensus, where the experts are separated into two different community groups: a climate and a hydrological modeller group. The dialogue reveals that under the conditions of the study, most climate modellers prefer the equal weighting of ensemble members, whereas hydrological impact modellers in general are more open for assigning weights to different models in a multi model ensemble, based on model performance and model structure. Climate experts are more open to exclude models, if obviously flawed, than to put weights on selected models in a relatively small ensemble. The study shows that expert elicitation can be an efficient way to assign weights to different hydrological models, and thereby reduce the uncertainty in climate impact. However, for the climate model ensemble, comprising seven models, the elicitation in the format of this study could only reestablish a uniform weight between climate models.

Eva Sebok et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2021-597', Anonymous Referee #1, 06 Jan 2022
  • EC1: 'Comment on hess-2021-597', Lelys Bravo de Guenni, 03 Jun 2022
  • RC2: 'Comment on hess-2021-597', Anonymous Referee #2, 19 Jul 2022
  • EC2: 'Comment on hess-2021-597', Lelys Bravo de Guenni, 21 Jul 2022

Eva Sebok et al.


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Short summary
Hydrological models projecting the impact of changing climate carry a lot of uncertainty. Thus, these models usually have a multitude of simulations using different future climate data. This study used the subjective opinion of experts to assess which climate and hydrological models are the most likely to correctly predict climate impacts, thereby easing the computational burden. The experts could select more likely hydrological models, while the climate models were deemed equally probable.