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Category: ensemble techniques

Large ensemble simulations for the study of extreme hydrological events

Large ensemble simulations for the study of extreme hydrological events

Contributed by Karin van der Wiel, KNMI*. The investigation of extreme hydrological events is often limited by the length of observed records or model simulations. For this reason many statistical extrapolation methods have been developed. In a recent GRL paper we advocate a novel method for the study of extreme events, which does not rely on such extrapolations (Van der Wiel et al., 2019). In this blog post I invite you to take a slight step outside the HEPEX world…

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Skilful seasonal forecasts of streamflow over Europe?

Skilful seasonal forecasts of streamflow over Europe?

Contributed by Louise Arnal, University of Reading & ECMWF Editor’s Note: Don’t miss the brilliant cartoon summary at the bottom of this post! Over recent decades, seasonal streamflow forecasting methods have evolved and diversified, reflecting changes in our scientific understanding of streamflow predictability on seasonal timescales and our increasing computer power. The first operational model-based ensemble seasonal streamflow forecast, called the ESP1,2 (ensemble streamflow prediction), relies on the correct knowledge of the initial hydrological conditions (IHC; i.e. of snowpack, soil…

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Using ensemble forecasts to inform risk-based operations of a reservoir in Northern California

Using ensemble forecasts to inform risk-based operations of a reservoir in Northern California

Contributed by:  Chris Delaney, Sonoma County Water Agency; John Mendoza, Sonoma County Water Agency; Brett Whitin, California Nevada River Forecast Center; Rob Hartman, Consultant Lake Mendocino is a reservoir located in Mendocino County, California, about 110 miles north of the City of San Francisco. This small 144 million cubic meter reservoir (Figure 1) releases water into the Russian River and provides both flood protection and water supply to downstream communities. Lake Mendocino is cooperatively managed by 2 government offices: the…

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Why are meteorologists apprehensive of ensemble forecasts?

Why are meteorologists apprehensive of ensemble forecasts?

Contributed by Anders Persson, Uppsala, Sweden A colleague in my world-wide meteorological network made me aware of a CALMet conference in Melbourne, i.e. dealing with meteorological education and training. Through the website you can access the program with more or less extensive abstracts. I have no doubt that most presentations were relevant and interesting, but what surprised me was that a search for the key words “probability” or “ensemble”  gave no hits. “Uncertainty” came up in only one (1) presentation,…

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Ensemble prediction: past, present and future

Ensemble prediction: past, present and future

Contributed by Fredrik Wetterhall and Roberto Buizza, ECMWF The work of producing meteorological ensemble forecasts started 25 years ago at ECMWF and NCEP, and it sparked a revolution in both weather forecasts and its many applications. To celebrate this occasion, more than 100 people from across the world joined the 28 speakers at ECMWF’s Annual Seminar 11-14 September held in Reading, UK. The theme was “Ensemble prediction: past, present and future” and the four days where filled with presentations and…

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