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COST 731


Propagation of uncertainty in advanced meteo-hydrological forecast systems

Project start01.01.2005
Project end31.12.2010
StatusCompleted projects
  • Research & cooperation
  • Weather


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Swiss federal authoritiesSwiss federal authorities

Quantifying uncertainty in flood forecasting is a difficult task, given the multiple and strongly non-linear model components involved in such a system.

The COST 731 Action (Rossa et al., 2009) is a European effort which deals with the quantification of forecast uncertainty in hydro-meteorological forecast systems and addresses three major lines of development:

  1. combining meteorological and hydrological models to form a forecast chain
  2. propagating uncertainty information through this chain and make it available to end users in a suitable form
  3. advancing high-resolution numerical weather prediction precipitation forecasts by using non-conventional observations from, for instance, radar to determine details in the initial conditions on scales smaller than what can be resolved by conventional observing systems.

Recognizing the interdisciplinarity of the challenge, COST 731 has organized its work forming Working Groups (WG) at the interfaces between the different scientific disciplines involved, i.e. between observation and atmospheric and hydrological modeling (WG1), between atmospheric and hydrologic modelling (WG2) and between hydrologic modelling and end-users (WG3). MeteoSwiss is chairing WG2 and doing research in the field of nowcasting orgraphic precipitation (PhD-Project).

MeteoSwiss contribution

The MeteoSwiss participation in COST-731 concentrates on two specific steps of the forecasting chain that are considered crucial for the transfer of uncertainty information into the hydrological application and end user involvement:

Focus 1: Nowcasting orographic precipitation

In a PhD project high-quality Doppler radar data, radiosoundings and ground stations measurements are being employed to establish an innovative heuristic forecasting system for the nowcasting of orographic precipitation. The system is based on the relation between orographic precipitation, mesoscale winds and airmass stability (Panziera and Germann, 2010).

Focus 2: Radar ensemble for runoff forecasting

In order to propagate uncertainty in radar precipitation fields into flash flood forecasting, a novel radar ensemble generator technology is developed and coupled in real-time with a hydrological model for runoff forecasting in a steep Alpine catchment (Germann et al, 2006a; Germann et al, 2009; Zappa et al, 2008).

This work is a logical continuation of many years of research at MeteoSwiss on radar precipitation measurement in mountainous regions (Germann et al, 2006b), studies of predictability of precipitation (Germann et al, 2006c), radar data assimilation in numerical weather prediction models (Leuenberger and Rossa, 2007), and nowcasting of thunderstorms in complex terrain (Hering et al, 2008).


Atencia A, U Germann, L Panziera, P Mandapaka, M Buzzi, A Hering, M Gabella, J Bech and T Rigo, 2010: Improving PQPF by probabilistic blending techniques. COST STSM 731-05737 scientific report, 25pp.

Atencia A, T Rigo, A Sairouni, J Morè, J Bech, E Vilaclara, J Cunillera, M C Llasat, L Garrote, 2010: Improving QPF by blending techniques at the Meteorological Service of Catalonia, Nat. Hazards Earth. Syst. Sci., 10: 1443-1455.

Panziera L, U Germann, 2010: The relation between airflow and orographic precipitation on the southern side of the Alps as revealed by weather radar, Quart. J. Roy. Meteor. Soc., 136: 222-238.

Panziera L, U Germann, M Gabella, PV Mandapaka, 2010: NORA ? Nowcasting of Orographic Rainfall by means of Analogs. Quart. J. Roy. Meteor. Soc., submitted

Rossa A, G Haase, C Keil, P Alberoni, S Ballard, J Bech, U Germann, M Pfeifer & K Salonen, 2010. Propagation of uncertainty from observing systems into NWP: COST-731 Working Group 1, Atmospheric Science Letters, 11: 145-152.

Zappa M, K Beven, M Bruen, A Cofino, K Kok, E Martin, P Nurmi, B Orfila, E Roulin, A Seed, K Schröter, J Szturc, B Vehviläinen, U Germann & A Rossa, 2010. Propagation of uncertainty from observing systems and NWP into hydrological models: COST-731 Working Group 2. Atmospheric Science Letters, 2: 83-91.


Germann U, M Berenguer, D Sempere-Torres and M Zappa, 2009: REAL - Ensemble radar precipitation estimation for hydrology in a mountainous region. Q J R Meteorol Soc, 135, 445-456, doi:10.1002/qj.375.

Friedrich K, U Germann and P Tabary, 2009: Influence of Ground Clutter Contamination on Polarimetric Radar Parameters. J Atmos Oceanic Technol, 26, 251-269.

Rossa A, K Liechti, M Zappa, M Bruen, U Germann, G Haase, C Keil, P Krahe. The COST 731 action: a review on uncertainty propagation in advanced hydro-meteorological forecast systems. Submitted to Atmospheric Research. Thematic Issue on COST-731.

Rossa A, F Laudanna Del Guerra & D Leuenberger. An Empirical Radar Data Quality Function. Proceedings of the AMS Radar Conference, 5-9 October 2009, Williamsburg, VA, USA, 2009, 8pp.

Rotach M and co-authors: 2009, MAP D-PHASE - Real-Time Demonstration of Weather Forecast Quality in the Alpine Region, Bull Amer Meteor Soc, 90 (9), 1321?1336, doi:10.1175/2009BAMS2776.1.

Zappa M, S Jaun, U Germann, A Walser, 2009. Superposition of three sources of uncertainties in operational flood forecasting chains in mountainous areas. Submitted to Atmospheric Research. Thematic Issue on COST-731.

Hering A, U Germann, M Boscacci, S Senesi, 2008: Operational nowcasting of thunderstorms in the Alps during MAP D-PHASE, Proceedings of the Fifth European Conference on Radar in Meteorology and Hydrology (ERAD), Helsinki.

Zappa Massimiliano, Mathias W. Rotach, Marco Arpagaus, Manfred Dorninger, Christoph Hegg, Andrea Montani, Roberto Ranzi, Felix Ament, Urs Germann, Giovanna Grossi, Simon Jaun, Andrea Rossa, Stephan Vogt, Andre Walser, Johannes Wehrhan and Claudia Wunram, 2008: MAP D-PHASE: Real-time demonstration of hydrological ensemble prediction systems. Atmos. Sci. Lett., 9, 80-87, doi:10.1002/asl.183.

Leuenberger D and A Rossa, 2007. Revisiting the latent heat nudging scheme for the rainfall assimilation of a simulated convective storm. Meteorology and Atmospheric Physics, 98 (3-4): 195-215.

Germann U, M Berenguer, D Sempere-Torres, G Salvadè, 2006a: Ensemble radar precipitation estimation - a new topic on the radar horizon. Proceedings of the Fourth European Conference on Radar in Meteorology and Hydrology (ERAD), Barcelona, 18-22 September 2006, 559-562.

Germann U, G Galli, M Boscacci & M Bolliger, 2006b: Radar precipitation measurement in a mountainous region. Quart. J. Roy. Meteor. Soc., 132, 1669-1692.

Germann U, I Zawadzki, B Turner, 2006c: Predictability of Precipitation from Continental Radar Images. Part IV: Limits to Prediction, J Atmos Sciences, 63, 2092-2108.