ABSTRACT:The verification of ensemble systems is being operationally carried out in several meteorological centres. However, the main operational ensemble systems have a coarser spatial resolution with respect to the deterministic runs. Only recently, high-resolution limited-area ensembles have started to be run on a regular basis. Their verification requires combining the usual probabilistic evaluation with the statistical verification techniques which are being developed for high-resolution model forecasts (1-10 km). These techniques permit to evaluate a deterministic forecast in a probabilistic manner, by taking into account the spatio-temporal distribution of the forecast at different scales.In this work, a spatial verification technique, called 'distributional method', is used to verify the Consortium for Smallscale MOdeling Limited-area Ensemble Prediction System (COSMO-LEPS) ensemble system, a mesoscale ensemble with 10 km horizontal resolution. The system is mainly designed to give probabilistic assistance in the forecast of severe weather, in particular of intense precipitation possibly leading to floods, hence verification is focused on the ability of the system in forecasting precipitation at high spatial resolution. The methodology is based on a comparison of forecasts and observations in terms of some parameters of their distributions, evaluated after the values are aggregated over boxes of selected size. In particular, performances in terms of average, a few percentiles and maximum forecast value in a box are considered.The system is compared against European Centre for Medium-Range Weather Forecasts Ensemble Prediction System (ECMWF EPS), addressing the issues of an intercomparison between a higher-resolution smaller-size ensemble and a lower-resolution larger-size one. Results show that when the forecast of the average amount of precipitation over an area is concerned, COSMO-LEPS is more skilful than the Ensemble Prediction System (EPS) only from the resolution point of view. Therefore, although not properly calibrated, it is more capable of distinguishing between events and non-events, especially for moderate and high precipitation. Furthermore, COSMO-LEPS has skill in forecasting the occurrence of precipitation peaks over an area, irrespective of the exact location.The analysis of the score behaviour as a function of the distribution parameter shows that EPS has the maximum skill in reproducing the central part of the observed precipitation distribution over an area of about 10 000 km 2 , while COSMO-LEPS is more skilful in reproducing the tail of the observed precipitation distribution.The problem of the predictability of precipitation at different spatial scales is also investigated, showing the role of different system resolutions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.