EGU21-2340, updated on 03 Mar 2021
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

ULYSSES: a system for global multi-model hydrological seasonal predictions

Luis Samaniego1, Stephan Thober1, Matthias Kelbling1, Robert Schweppe1, Oldrich Rakovec1, Pallav Shrestha1, Alberto Martinez-de la Torre2, Eleanor M. Blyth2, Katie A. Smith2, Gwyn Rees2, Matthew Fry2, Edwin Sutanudjaja3, Niko Wanders3, Marc FP Bierkens3, and Rens van Beek3
Luis Samaniego et al.
  • 1Helmholtz Centre for Environmental Research - UFZ, Department Computational Hydrosystems, Leipzig, Germany (
  • 2UK Centre for Ecology and Hydrology, Wallingford, United Kingdom
  • 3Utrecht University, Department of Physical Geography, Utrecht, Netherlands

The Copernicus Climate Change Service aims at facilitating the emergence of a downstream market of climate services with the ultimate goal of supporting the development of a climate-smart society. Central to this vision is the free and unrestricted distribution of high-quality climate data through the Climate Data Store [1], with seasonal meteorological predictions among them. Within this unique and challenging framework, ULYSSES [2] will provide the first "seamless'' multi-model hydrological seasonal prediction system, with a global coverage at a spatial resolution of 0.1° The ULYSSES modeling chain is based on the successfully tested EDgE proof of concept [3] using four state-of-the-art hydrological models (Jules, HTESSEL, mHM, and PCR-GLOBWB). A unique feature of this production chain consists of using the same land surface datasets (e.g. DEM, soil properties) with identical spatio-temporal resolutions and forecast inputs for all HMs, and the same river routing scheme (i.e., the multi-scale routing model mRM).

The initial conditions of the production chain will be based on ERA5-Land dataset and the seasonal forecasts will be driven by a 25-member ensemble generated by the ECMWF-SEAS5 model. ULYSSES aims at generating six essential hydrological variables: snow-water equivalent, snowmelt, evapotranspiration, soil moisture, total runoff, and streamflow with a lead-time of up to six months.  The seasonal forecast was verified at 250+ gauges distributred in all continents during the hind-casting period from 1993 to 2019. The operational forecasting period —in testing phase— started in January 2021 and be extended through until July 2021.  The first operational ULYSSES forecast will be made available by the 10th of each month starting in January 2021.

All input data sets (ERA5-Land), seasonal forecasts (SEAS5) and ULYSSES outputs will be made available in the Copernicus Climate Data Store [1] and will be open access. We aim to engage institutions and researchers around the world that are willing to evaluate the forecasts model performance, with the aim of improving the system in the future. In this talk, the modelling chain concept, model setup and verification of initial results will be presented.

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How to cite: Samaniego, L., Thober, S., Kelbling, M., Schweppe, R., Rakovec, O., Shrestha, P., Martinez-de la Torre, A., Blyth, E. M., Smith, K. A., Rees, G., Fry, M., Sutanudjaja, E., Wanders, N., Bierkens, M. F., and van Beek, R.: ULYSSES: a system for global multi-model hydrological seasonal predictions, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2340,, 2021.


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