Attributes of Forecast Quality
Forecast verification is a process used to assess the quality of hydrometeorological ensemble forecasts. This chapter describes the many aspects of forecast quality using a distributions-oriented approach. Using the joint distribution of forecasts and observations, or one of its factorizations into a conditional and marginal distribution, the aspects of forecast quality are defined. Hypothetical ensemble forecasts are then used to illustrate aspects of forecast quality. The hypothetical ensemble forecasts are used to construct single-valued forecasts, probability forecasts for an event, and ensemble probability distribution forecasts. Their forecast quality is then diagnosed using visual comparisons and numerical comparisons of forecast quality measures. The examples illustrate that a single aspect of forecast quality is insufficient and that many aspects are needed to understand the nature of the forecasts. Some practical considerations in the application of the framework to ensemble forecast verification are discussed.
KeywordsForecast verification Ensemble forecasts Deterministic forecasts Probabilistic forecasts Distributions-oriented approach
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