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Kirstin Kober, Annette M. Foerster, and George C. Craig

radar observations, and the applied quality measures. The ensembles with conventional and stochastic convection parameterization are evaluated in two case studies representing strong and weak large-scale forcing in section 3 in terms of general properties and deterministic and probabilistic forecast quality measures. The results are discussed in section 4 and final conclusions are drawn. 2. Data and methods In this study, ensembles of precipitation forecasts calculated with the COSMO model using

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Lars Wiegand, Arwen Twitchett, Cornelia Schwierz, and Peter Knippertz

. Buizza et al. (2005) compared the European Centre for Medium-Range Weather Forecasts (ECMWF) Ensemble Prediction System (EPS), National Centers for Environmental Prediction (NCEP) EPS, and the Canadian Meteorological Centre (CMC) EPS in a comprehensive study. Bourke et al. (2004) tested ECMWF and Australian Bureau of Meteorology (BoM) predictions on their performance in the Southern Hemisphere. Both studies find a better level performance for the ECMWF model and suggest a relation to the superior

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Martin Weissmann, Florian Harnisch, Chun-Chieh Wu, Po-Hsiung Lin, Yoichiro Ohta, Koji Yamashita, Yeon-Hee Kim, Eun-Hee Jeon, Tetsuo Nakazawa, and Sim Aberson

forecasts by different models is presented in section 3 , followed by a discussion of the influence of T-PARC observations on ECMWF forecasts in midlatitudes over the Pacific and on the Northern Hemisphere in section 4 . The discussion and conclusions are presented in section 5 . 2. Model descriptions a. JMA GSM experiment description To evaluate the impact of the T-PARC 2008 special observations, experiments using the operational global 4D-Var system and the operational JMA global spectral model

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Kirstin Kober and George C. Craig

the perturbation method is applicable in any atmospheric model that allows for calculation of the relevant physical process information. The observational data used to evaluate the forecasts and the selected case studies in which the parameterization is tested will be introduced briefly as well as the analysis strategy for the suggested method. a. Physically based stochastic perturbations in the boundary layer We propose a concept of process-based model error representation in terms of a

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Paraskevi Giannakaki and Olivia Martius

Coauthors , 2011 : The ERA-Interim reanalysis: Configuration and performance of the data assimilation system . Quart. J. Roy. Meteor. Soc. , 137 , 553 – 597 , doi: 10.1002/qj.828 . ECMWF , 2008 : Changes in ECMWF model: CY33r1. [Available online at .] Fehlmann, R. , and Davies H. C. , 1997 : Misforecasts of synoptic systems: Diagnosis via PV retrodiction . Mon. Wea. Rev. , 125 , 2247 – 2264 , doi: 10

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Gabriel Wolf and Volkmar Wirth

. 2c ) is poor, and other values for s 0 do not solve the problem either [see Zimin et al. (2003) ]. The better performance of the Hilbert transform technique in the above situation seems to suggest that this technique is superior, and possibly this is the reason for its recent popularity. Yet, the example in (5) is somewhat contrived. In real atmospheric flows there is generally a broad spectrum of zonal wavenumbers, and the reconstruction of the envelope is often not very sensitive to the

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Maxi Boettcher and Heini Wernli

forecast performance of the deterministic ECMWF model for this particular event. In the next section the data and tools used in this study will be introduced. Section 3 contains a synoptic description of the cyclone life cycle and an analysis of the structure of the system for each development phase. With the aid of a quasigeostrophic vertical motion diagnostic the influence of the upper-level forcing on the low-level system will be investigated. The forecast performance of this event will be

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Florian Harnisch and Martin Weissmann

subsets does not show the best performance and the 12–120-h mean track forecast error reduction of allObs is 28%, while 16% can be achieved with the ReObs run and 51% with the ViObs run. Despite the improvement of the track until the recurvature of the storm, the model seems to have problems with the propagation of Sinlaku after recurvature. From 84 h onward, a timing error of all track forecasts is observed ( Fig. 7c ). Even if the track forecast error is reduced with extra observations, the error

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Christian M. Grams and Heather M. Archambault

1. Introduction The large-scale midlatitude flow is dominated by the upper-level jet stream that serves as a waveguide for Rossby waves (e.g., Martius et al. 2010 ). Because their general evolution follows dry dynamics that can be represented at grid scale in numerical weather prediction (NWP) models, Rossby waves may be expected to feature a high degree of predictability ( Grazzini and Vitart 2015 ). However, major forecast uncertainty and error in the midlatitudes in current NWP models have

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Jana Čampa and Heini Wernli

, heat content, and precipitable water in North Atlantic cyclones. Mass and Dotson (2010) considered the structure of the strongest cyclones in the northwestern United States. They found the strongest winds southeast of the cyclones and interestingly a cold temperature anomaly at 850 hPa in the center. A bent-back warm front was found to be a typical feature of these storms. Considering the structure of extratropical cyclones is also an important aspect when evaluating climate model simulations

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