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[en] Four methods of classifying atmospheric stability class are applied at four sites to make short-term (1-h) dispersion estimates from a ground-level source based on a model consistent with U.S. Nuclear Regulatory Commission practice. The classification methods include vertical temperature gradient, standard deviation of horizontal wind direction fluctuations (sigma theta), Pasquill-Turner, and modified sigma theta which accounts for meander. Results indicate that modified sigma theta yields reasonable dispersion estimates compared to those produced using methods of vertical temperature gradient and Pasquill-Turner, and can be considered as a potential economic alternative in establishing onsite monitoring programs. (author)
[en] We suggest that measuring the variation of the radius of an atomic cloud when the harmonic trap confinement is varied makes it possible to monitor the disappearance of the insulating Mott phase of an ultracold atomic gas trapped in a disordered optical lattice. This paves the way for an unambiguous identification of a Bose glass phase in the system
[en] We consider diffusion of a cold Fermi gas in the presence of a random optical speckle potential. The evolution of the initial atomic cloud in space and time is discussed. Analytical and numerical results are presented in various regimes. Diffusion of a Bose-Einstein condensate is also briefly discussed and similarity with the Fermi gas case is pointed out.
[en] A model for the motion of dust particles in the atmosphere, forming noctilucent clouds, is developed. The equilibrium particle positions are calculated for different initial conditions. The analysis of the time evolution of the particle radius and the particle positions gives rise to oscillating behavior, which was also obtained in earlier models
[en] The noise (fluctuation)-induced transitions between two states have fundamental importance in many physical systems. The quantitative understanding about the bistable systems was the Kramer's equation on the escape rate from a potential well. Theoretical and some experimental studies were extended to comprehend transitions between driven bistable systems that are not static potentials but oscillating ones periodically. Two atomic clouds that oscillate oppositely visualized the dynamic double wells. Different from previous experiments, since there are many particles in ours, the transitions were observed directly as exponential decay and growth of each state after removing population in one of two states. The noise (fluctuations), the main reasons of 5 transitions, are the spontaneous emissions for our atomic systems, which could be controlled the intensity and detuning of the laser going perpendicularly to the limit cycle motion. We have studied the transition rates according to the amount of diffusions from spontaneous emissions, the modulation frequency and the modulation amplitude.
[en] A two-dimensional version of the cloud model has been adapted for the analysis of transport of radionuclides in atmosphere and for the radiological impact assessment. The possibilities of the model have been analyzed for various meteorological conditions. The possibilities of the presented model are compared with other models for similar studies. (author)
[en] The Meteorological Network department is concerned with observations of meteorological elements and phenomena. Its activities include observation of clouds. Cloudiness is characterized by three variables: - Cloudiness; - the type of cloud; - the height of the base clouds. The morphological classification of the clouds is based on the overall appearance of the cloud. Clouds are classified according to species, shape, variety and peculiarities. (authors)
[en] Meridional profiles of turbidity at some periods after the explosion of Katmai volcano in June 1912 at 58degreeN are compared with debris burden from Chinese nuclear tests. Katmai turbidity was previously obtained from solar radiation data, and debris burden was calculated from published mixing ratio data. Turbidity and burden generally peak strongly in arctic latitudes. Only two tests show indications of a bulge at 30degree-45degreeN which probably existed for Katmai dust in spring 1913. The residence time of Katmai dust was found to have been about 1 year, whereas fallout of nuclear debris seems not to have started before the winter following the tests. For September 1912 the total amount of Katmai aerosol is estimated to have been 13 million metric tons. Analogies to predicted meridional distribution of SST pollutants are being mentioned
[en] APUD is a computed code designed for rough, expeditious assessments of the dispersal of airborne radioactivity discharged, either normally or accidentally, from nuclear facilities. In particular codes such as APUD may aptly complement the tool-kit required in the adoption of informed contingency plans in case of abnormal nuclear occurences that are accompanied by atmospheric releases of radioactivity. Apart from such extreme circumstances, APUD may profitable be used a a simulation/drill facility. Given adequate inputs, APUD may also work on any sort of industrial atmospheric emissions.(author)
[en] Following a reactor accident, relatively high contamination at ground level can occur, even at quite long distances from the source, if the pollutant cloud encounters intense precipitation. To estimate such contamination and its extent properly, it is necessary to take into account the spatial and temporal structure of rain patterns and their motion. Currently, models of wet deposition are rather crude. Source meteorology is usually used and is clearly inadequate. Furthermore, no allowance is made for the dynamic nature of rainfall, which occurs as a result of vertical air motions and convergence; nor for the different scavenging mechanism operating in and below cloud. Meteorological information available on these aspects of wet deposition is reviewed, and their importance and inclusion in modelling and prediction of resulting ground contamination is indicated. Some of the pitfalls of simple modelling procedures are illustrated. (author)