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Assimilation of water temperature and discharge data for ensemble water temperature forecasting.

Ouellet-Proulx, Sébastien; Chimi Chiadjeu, Olivier; Boucher, Marie-Amélie; St-Hilaire, André (2017). Assimilation of water temperature and discharge data for ensemble water temperature forecasting. Journal of Hydrology , vol. 554 . p. 342-359. DOI: 10.1016/j.jhydrol.2017.09.027.

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Résumé

Recent work demonstrated the value of water temperature forecasts to improve water resources allocation and highlighted the importance of quantifying their uncertainty adequately. In this study, we perform a multisite cascading ensemble assimilation of discharge and water temperature on the Nechako River (Canada) using particle filters. Hydrological and thermal initial conditions were provided to a rainfall-runoff model, coupled to a thermal module, using ensemble meteorological forecasts as inputs to produce 5 day ensemble thermal forecasts. Results show good performances of the particle filters with improvements of the accuracy of initial conditions by more than 65% compared to simulations without data assimilation for both the hydrological and the thermal component. All thermal forecasts returned continuous ranked probability scores under 0.8 °C when using a set of 40 initial conditions and meteorological forecasts comprising 20 members. A greater contribution of the initial conditions to the total uncertainty of the system for 1-dayforecasts is observed (mean ensemble spread = 1.1 °C) compared to meteorological forcings (mean ensemble spread = 0.6 °C). The inclusion of meteorological uncertainty is critical to maintain reliable forecasts and proper ensemble spread for lead times of 2 days and more. This work demonstrates the ability of the particle filters to properly update the initial conditions of a coupled hydrological and thermal model and offers insights regarding the contribution of two major sources of uncertainty to the overall uncertainty in thermal forecasts.

Type de document: Article
Mots-clés libres: data assimilation; particle filter; discharge; water temperature; ensemble forecasts; uncertainty
Centre: Centre Eau Terre Environnement
Date de dépôt: 08 mai 2018 14:42
Dernière modification: 08 mai 2018 14:42
URI: http://espace.inrs.ca/id/eprint/6560

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