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Influence of computational grid resolution on the quality of forecasts of dangerous convection phenomena: a case study of August 11, 2017

Mazur Andrzej, Duniec Grzegorz

Meteorology Hydrology and Water Management. Research and Operational Applications

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2022

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Vol. 10, Iss. 2

106--114

EN

On August 11, 2017, a violent convection phenomenon took place in northwestern Poland, i.e., a storm combined with intense rainfall and hurricane winds. This paper presents an attempt to analyze this case by using the results of a numerical weather model, at grid spacings of 7 km, 2.8 km, and 0.7 km. Various convective indicators were analyzed to assess the nature of the event. The key question the authors try to answer is: „To what extent, if any, did a tenfold increase in resolution improve the quality of the numerical forecasts?” This question, however, has not been conclusively resolved. The most likely cause of this event was a supercell rapidly moving from south to northeast. This supercell's path has been mapped (qualitatively at least) by the Supercell Detection Index at all resolutions used. As the resolution increased, the forecasted maximum gusts also increased from 25 m/s in the domain with a resolution of 7 km to 35 m/s at a resolution of 2.8 km and up to about 50 m/s at the highest resolution of 0.7 km. A key conclusion is that the results of the model at a resolution of 2.8 km are much closer to reality than at 7 km. This effect did not pertain to differences between the 2.8 km and 0.7 km models. The latter increase in resolution did not significantly improve the quality of the forecast.

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Dependence of skill and spread of the ensemble forecasts on the type of perturbation and its relationship with long term norms of precipitation and temperature

Duniec Grzegorz, Mazur Andrzej

Acta Geophysica

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2020

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Vol. 68, no. 5

1505--1528

EN

A new computing cluster has been operating since 2016 at the Institute of Meteorology and Water Management – National Research Institute. Increasing computing power enabled the implementation of ensemble prediction system forecasts in the operational mode and the use of a new computer for research purposes. As part of the priority project on “Study of Disturbances in the Representation of Modeling Uncertainty in Ensemble Development” and the earlier project entitled “COSMO Towards Ensemble in Km in Our Countries), implemented in the Working Group 7 (Predictability and Ensemble Methods) as part of the COSMO modeling consortium, specifc studies were carried out to test ensemble forecasts. This research concerned the impact of variability of physical felds characterizing the soil surface (a selected parameter determining evaporation from the soil surface and soil surface temperature) using various methods of perturbation. Numerical experiments were completed for the warm period (from June to September) 2013.

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Refrakcja troposferyczna w świetle meteorologicznych mezoskalowych modeli prognostycznych

Figurski M., Kroszczyński K.

Geomatics and Environmental Engineering

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2007

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Vol. 1, no. 1/1

169-176

PL

W artykule przedstawiono metodę wyznaczania opóźnienia skośnego GPS w oparciu o dane analiz i prognoz niehydrostaycznego modelu atmosfery COAMPS (Coupled Ocean/Atmosphere Mesoscale Predition System), który został uruchomiony w trybie operacyjnym na klastrze komputerowym IA64 Centrum Geomatyki Stosowanej Wydziału Inżynierii Lądowej i Geodezji Wojskowej Akademii Technicznej. Opóźnienie skośne otrzymano, całkując przestrzenną funkcję refrakcji troposferycznej wzdłuż drogi propagacji fali GPS. Drogę określono, rozwiązując układ równań różniczkowych promienia, który wynika z równania eikonału. Do wyznaczenia pola refrakcji atmosferycznej wykorzystano parametry stanu atmosfery z modelu COAMPS.

EN

The paper presents a method of determining the GPS slant delay on the basis of diagnostic and forecasted data from the COAMPS (Coupled Ocean/Atmosphere Mesoscale Prediction System) non-hydrostatic model of the atmosphere which is run in operational mode on a IA64 computer cluster in the Applied Geomatics Section, Faculty of Civil Engineering and Geodesy, Military University of Technology. The slant delay value was obtained by integrating the spatial function of the tropospheric refraction along the GPS wave propagation path. The path was determined from the solution of the differential equations system of the path ray that results from the eikonal equation. The atmospheric refraction field was determined using the atmospheric parameters obtained from the COAMPS model.