National Repository of Grey Literature 26 records found  beginprevious17 - 26  jump to record: Search took 0.01 seconds. 
Data assimilation methods for early and late phase of radiation accident - A comprehensive review with examples of methods examined within solution of the grant projet VG20102013018
Hofman, Radek ; Pecha, Petr ; Šmídl, Václav
The task of the decision support in the case of a radiation accident is to provide up-to-date information on the radiation situation, prognosis of its future evolution and possible conse- quences. The reliability of predictions can be significantly improved using data assimilation, which refers to a group of mathematical methods allowing an efficient combination of ob- served data with a numerical model. The concerns application of the advanced data assimilation methods in the field of radiation protection. We focus on assessment of off-site consequences in the case of a radiation accident when radionuclides are released into the environment. In this report we present a comprehensive review of data assimilation evaluated for pur- poses of inclusion into the data assimilation and decision support system ASIM developed within the grant project VG20102013018 provided by the Ministry of the Interior of the Czech Republic.
Nesting of Data Assimilation Cycles into the Recursive Model Predictions
Pecha, Petr ; Kuča, P.
Model errors analysis, influence of variability of important meteorological inputs. Specific features of introduction of advanced assimilation techniques based on merging of all available associated information including real observations incoming from terrain.
Monitoring of radiation in the early phase of an accident at a nuclear facility - an analysis of all types of measurement applicable to the correction of model predictions
Pecha, Petr ; Kuča, Petr ; Češpírová, Irena ; Hofman, Radek
Zpráva se zaměřuje na metody monitorování radioaktivního znečistění v časné fázi nehody spojené s únikem radioaktivity do životního prostředí. Cílem prováděného rozboru je určit ty metody monitorování prováděné stávajícími radiačními sítěmi, které mohou poskytovat měření z terénu pro jejich další využití v oblasti zlepšování modelových předpovědí vývoje radiační situace. Pro tyto účely byly vyvinuty speciální statistické metody bayesovské filtrace provádějící asimilaci modelových předpovědí s měřeními z terénu.
Asimilace časoprostorového rozložení radionuklidů v časné fázi radiační nehody
Hofman, Radek ; Šmídl, Václav
Exploitation of the data assimilation methodology in the early phase of radiation accident is studied. When radioactive pollutants are released into the atmosphere, a radioactive plume is passing over the terrain. The released radioactive material causes pathway-specific irradiation which has detrimental effects on population health. In order to ensure efficiency of introduced countermeasures, it is necessary to predict spatial and temporal distribution of the aerial pollution and material already deposited on the ground. The predictions are made by the means of a numerical dispersion model with many inputs. Output of such a model is a prediction of radiation situation given in terms of radiological quantities. Exact values of the inputs are uncertain due to the stochastic nature of the dispersion, lack of accurate information, etc. Their subjective choice can introduce significant errors into the predictions and thus decrease the positive impact of the countermeasures.
Asimilace satelitních a přízemních dat do modelů kvality ovzduší
Resler, Jaroslav ; Eben, Kryštof ; Juruš, Pavel ; Krč, Pavel
Tropospheric columns of various species retrieved from satellite instruments bring a new quality into data assimilation systems for air quality models. In our experiments we assimilate tropospheric columns of NO2 retrieved from the instruments GOME2 and OMI together with ground-level observations of NO2. The 4DVar method has been used to optimize both initial conditions and suitable parameters of the emission model. A forecast experiment has been performed and the contribution of data assimilation to the one-day-ahead forecast has been studied.
Techniques of empirical and statistical interpolation used for correction of models of pollution propagation
Pecha, Petr ; Hofman, R.
Methods for correction of the mathematical model results using odservations from terrain. Utilisation of classical empirical interolation techniques and statistical approach of optimal interpolation method are investigated. Advantage of statistical method is demonstrated on example of atmospheric radionuclide release with rain occurrence.
Downscaling in the Context of Data Assimilation
Juruš, Pavel
Feasibility of common framework for the data assimilation and downscaling methods is investigated and discussed. Assimilation of measurements from ground level oyone stations with limited representativity to chemistry transport model is selected as an example and first results with simple decomposition to the local and background component are presented.
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