No (263)
Yes (11)
Number of found documents:
274
Published from
to
Analysis of temporal variability and spatial characteristics of heat waves in central Europe using extremity index
Lhotka, Ondřej; Kyselý, Jan
2013 - English
Heat waves have severe consequences on natural environment and society. Th e majority of studies defined heat waves from station data only, so there is a need to examine these events not only from the aspect of point characteristics of air temperature and duration, but also from the view of their spatial extent. In this study, heat waves over Central Europe were analysed using the gridded E-OBS dataset. Th e extremity index of heat waves, which takes into account their spatial extent, duration, and peak temperature, was proposed and used to analyse variability of heat waves over Central Europe from 1950 to present. We delimited 220 hot days and 21 heat waves and computed the extremity index for each heat wave. Th e eight most signifi cant heat waves based on the extremity index were visualized. Temporal variability of hot days and heat waves was analysed and we demonstrate that the number of hot days and the severity of heat waves have been increasing.
Keywords:
heat waves; central Europe; extremity index
Available at various institutes of the ASCR
Analysis of temporal variability and spatial characteristics of heat waves in central Europe using extremity index
Heat waves have severe consequences on natural environment and society. Th e majority of studies defined heat waves from station data only, so there is a need to examine these events not only from the ...
On Forward and Backward Scattering from Fog and Rain Drops
Fišer, O.; Rejfek, Luboš; Brázda, Vladimír
2013 - English
This contribution deals with the backward and forward scattering on dielectrical spheres. The well-known Rayleigh, Mie and Optical regions are discussed for frequencies regions 0.05 to 70 GHz and for optical wavelength of 830 nm. Some of our results fit the published one, some of them are different and the explanation of possible reasons is added. Also the formulas necessary to compute the radar reflectivity or attenuation due to fog and rain are presented.
Keywords:
Forward scattering; backward scattering; efficiency factor; Rayleigh region; Mie region; Optical region; mlha; déšť
Available at various institutes of the ASCR
On Forward and Backward Scattering from Fog and Rain Drops
This contribution deals with the backward and forward scattering on dielectrical spheres. The well-known Rayleigh, Mie and Optical regions are discussed for frequencies regions 0.05 to 70 GHz and ...
Metody odhadu extrémních srážek a jejich aplikace v ČR
Picek, J.; Kyselý, Jan; Gaál, Ladislav
2013 - Czech
Příspěvek shrnuje koncepce a metodické postupy, na jejichž základě byla řešena problematika odhadu pravděpodobnosti extrémních srážek a návrhových hodnot v ČR v nedávném období. The paper summarizes concepts and methods applied in estimation of probabilities of extreme precipitation amounts and design precipitation in the Czech Republic in the recent past. This work was motivated by the occurrence of several extraordinary precipitation events that resulted in floods with enormous material damages, but also by advances in the field of statistical modelling of extremes. The methods that we introduce are split in two main parts: methods for estimation of probable maximum precipitation and methods for estimation of design precipitation using different variants of the regional frequency analysis. In the concluding section several open issues and possible directions of follow-up research and improvements are outlined.
Keywords:
precipitation extremes; design values; probable maximum precipitation; regional frequency analysis
Fulltext is available at external website.
Metody odhadu extrémních srážek a jejich aplikace v ČR
Příspěvek shrnuje koncepce a metodické postupy, na jejichž základě byla řešena problematika odhadu pravděpodobnosti extrémních srážek a návrhových hodnot v ČR v nedávném období....
Kvantitativní odhad úniku polétavého prachu z Dolu Bílina do okolí (etapa 2)
Sokol, Zbyněk; Svoboda, Jaroslav
2013 - Czech
Cílem této studie je výpočet průměrných ročních relativních depozic polétavého prachu na území Dolu Bílina během roku 2012. Relativní depozice jsou vyjádřeny v procentech celkové hmoty prachu, který byl vytvořen v důsledku těžební činnosti. Tyto výpočty byly provedeny pro dvě velikosti prachových částic (PM10, PM2.5) a pro různé typy zdrojů (rypadla, zakladače apod.). Výpočet průměrných ročních relativních depozic byl založen na statistickém zpracování vypočtených depozic pro konkrétní proudové scénáře. Pomocí spočtených proudových scénářů a měření na referenční meteorologické stanici byla vždy nejprve vygenerována virtuální časová řada pro tu veličinu, která byla statisticky zpracovávána. Virtuální časová řada byla zpracována standardními statistickými metodami. The aim of this study was to calculate the relative deposition of dust in the mine Bílina during the year 2012. The relative deposition was expressed in percentage of a total mass of dust that was created as a result of mining activities . These calculations were made for two sizes of dust (PM10 , PM2.5) and for different types of resources excavators, loaders, etc.). The annual average of the relative deposition was obtained by statistical processing of the calculated deposition for various meteorological scenarios. The scenarios were determined using the local meteorological measurements.
Keywords:
atmosphere; pollution; PM10; PM2.5; boundary layer; high resolution modelling
Available at various institutes of the ASCR
Kvantitativní odhad úniku polétavého prachu z Dolu Bílina do okolí (etapa 2)
Cílem této studie je výpočet průměrných ročních relativních depozic polétavého prachu na území Dolu Bílina během roku 2012. Relativní depozice jsou vyjádřeny v procentech celkové hmoty prachu, který ...
Occurrence Rate of Equatorial Noise Emissions as a Function of the McIlwain's Parameter
Hrbáčková, Zuzana; Santolík, Ondřej
2012 - English
We report results of a statistical analysis of equatorial noise (EN) emissions based on the data set collected by the four Cluster spacecraft between January 2001 and December 2010. We have investigated a large range of the McIl- wain’s parameter from L 1 to L 11 thanks to the change of orbital parameters of the Cluster mission. We have processed data from the STAFF-SA instruments which analyze measurements of electric and magnetic field fluctuations onboard and provide us with hermitian spectral matrices. We have used linear polarization of magnetic field fluctuations as a selection criterion. Propagation in the vicinity of the geomagnetic equator has been used as an additional criterion for recognition of EN. We have identified about 6000 equatorial passages of all four spacecraft during the investigated time period and about 2000 passages in which we observed EN emissions. We demonstrate that EN can occur almost at all the analyzed L shells. However, the occurrence rate at L shells below 2 and above 8.5 is very low. At L shells above 10 the occurrence rate is zero. We show that EN is dependent on the magnetic local time.
Keywords:
Cluster spacecraft; Earth's magnetosphere; equatorial noise emission; magnetic local time
Available at various institutes of the ASCR
Occurrence Rate of Equatorial Noise Emissions as a Function of the McIlwain's Parameter
We report results of a statistical analysis of equatorial noise (EN) emissions based on the data set collected by the four Cluster spacecraft between January 2001 and December 2010. We have ...
Rain impact on FSO link attenuation based on theory and measurement
Brázda, V.; Schejbal, V.; Fišer, Ondřej
2012 - English
The FSO link becomes a usual mean of modern wireless communications. But it suffers from atmospheric particles causing attenuation. That´s why this random attenuation must be carefully considered by the FSO link design. As it is known the most serious atmospheric phenomenon is fog, and low cloudiness. But the rain attenuation (night mare of mm wave links) is not negligible on optical links, too. In this contribution we focus on rain attenuation from theoretical as well as experimental point of view. Statistics and rain event analysis are shown. There is an overview and a comparison of several formulas for rain attenuation derived from DSD or rain rate. Rain is not the worst phenomena for the transmission but we can’t neglect its influence on FSO. Only full understanding of influence of real atmosphere can lead to solution of a high availability of FSO systems.
Keywords:
Free-space optics; atmospheric attenuation; rain rate
Available at various institutes of the ASCR
Rain impact on FSO link attenuation based on theory and measurement
The FSO link becomes a usual mean of modern wireless communications. But it suffers from atmospheric particles causing attenuation. That´s why this random attenuation must be carefully considered by ...
Kvantitativní odhad úniku polétavého prachu z Dolu Bílina do okolí (etapa 1)
Sokol, Zbyněk; Svoboda, Jaroslav; Pešice, Petr
2012 - Czech
Zpráva popisuje postup prací a získané výsledky při modelování šíření prachu uvnitř dolu Bílina a v jeho blízkém okolí. Byl vyvinut model pro výpočet proudění v dole a okolí s vysokým rozlišením (25 m) a model přenosu prachu a výpočtu koncentrací PM10 a PM2.5. Oba modely byly ověřeny na konkrétních datech. The report describes applied methods and results obtained in modelling the dust spread inside the mine Bílina and its surroundings . We developed a model calculating air flow in the mine and its surrounding area with a horizontal resolution of 25 m and a transfer model calculating the concentration of dust PM10 and PM2.5 . Both models were validated using measured data.
Keywords:
atmosphere; pollution; PM10; PM2.5; model
Available at various institutes of the ASCR
Kvantitativní odhad úniku polétavého prachu z Dolu Bílina do okolí (etapa 1)
Zpráva popisuje postup prací a získané výsledky při modelování šíření prachu uvnitř dolu Bílina a v jeho blízkém okolí. Byl vyvinut model pro výpočet proudění v dole a okolí s vysokým rozlišením (25 ...
The STEREO/Waves Goniopolarimetric Products for Centre de Données de la Physique des Plasmas
Krupař, Vratislav; Cecconi, B.; Maksimovic, M.; Nguyen, Q. N.; Santolík, Ondřej
2011 - English
We present results on the calibration of the HFR receiver, a part of the S/Waves instrument onboard the STEREO spacecraft. The HFR provides us with GP measurements in the frequency range 125–1975 kHz. The obtained data products will be archived in the Plasma Physics Data Center: CDPP. This paper contains a description of used methods and summarizes outputs of the calibration.
Keywords:
Solar Radio Emissions; Goniopolarimetric inversion
Available at various institutes of the ASCR
The STEREO/Waves Goniopolarimetric Products for Centre de Données de la Physique des Plasmas
We present results on the calibration of the HFR receiver, a part of the S/Waves instrument onboard the STEREO spacecraft. The HFR provides us with GP measurements in the frequency range 125–1975 ...
Vliv dešťových srážek na koncentraci prachu v ovzduší
Fišák, Jaroslav; Bartůňková, Kristýna
2011 - Czech
V tomto příspěvku je pozornost věnována vlivu srážek na množství prachu v ovzduší. Jsou použity dvě charakteristiky srážek: srážkový úhrn a doba trvání srážek. Pro stanovení koncentrace prachu v ovzduší je využita suchá filtrovací metoda, kdy byl vzduch nasáván vývěvou přes hlavici s filtrem. Expozice filtru byla cca 1 týden. Doba odběru vzorků nebyla zcela konstantní. Proto bylo nutno přistoupit na relativní charakteristiky. Zvolen byl srážkový úhrn připadající na 1 den expozice filtru. Ještě složitější bylo charakterizovat dobu trvání srážek. Zde bylo zvoleno procentuální vyjádření doby trvání srážek vzhledem k době expozice filtru. Bylo zjištěno, že v období, kdy se vyskytují jen kapalné srážky, je koncentrace prachu v ovzduší silně ovlivněna jejich výskytem. Lze předpokládat, že část prachu je zachycena vodními kapičkami. Část prachu se do ovzduší vůbec nedostane. S růstem doby trvání i množství srážek klesá koncentrace prachu v ovzduší. In this contribution the impact of precipitation on the amount of dust in the air is studied. Two precipitation characteristics are used: precipitation amount and time of precipitation duration. For the determination of dust concentrations dry filtering method was used. By this method the air is being sucked in by the suction pump over the head with filter. The exposition of the filter lasted approximately one weak. The time of samples collecting was not absolutely constant. Therefore it was necessary to choose relative characteristics. Precipitation amount for daily exposition of the filter was used. Even more difficult was to characterize the time of precipitation duration. In this case percent expression of precipitation duration to the time of filter exposition was used.
Keywords:
dust in the air; precipitation amount; time of precipitation duration
Available at various institutes of the ASCR
Vliv dešťových srážek na koncentraci prachu v ovzduší
V tomto příspěvku je pozornost věnována vlivu srážek na množství prachu v ovzduší. Jsou použity dvě charakteristiky srážek: srážkový úhrn a doba trvání srážek. Pro stanovení koncentrace prachu v ...
Influence of Non-vertical Echoes to Ionogram Scaling
Kouba, Daniel; Koucká Knížová, Petra
2011 - English
Digisonde DPS 4 replaced the older ionosonde IPS 42 KEL Aerospace in the Observatory Pruhonice in January 2004. Additional information about the wave polarization enables us to determine and to distinguish exactly between ordinary and extraordinary wave traces on the ionogram records. This new ability basically changes scaling of the ionograms comparing to the ionograms obtained by classical ionosondes. Digisonde measurements show that in some cases the interpretation of ionograms based on classical ionospheric soundings may lead to the systematic errors, which affect classical ionograms interpretation. We demonstrate possible significant misinterpretations of the ionograms obtained using the classical equipment that is not able to distinguish between ordinary and extraordinary modes and records only time of flight of the electromagnetic sounding pulse. We show the necessity to be careful in using an old ionosonde measurements and scaled data for further analysis.
Keywords:
Digisonde; ionogram interpretation; spread F
Available at various institutes of the ASCR
Influence of Non-vertical Echoes to Ionogram Scaling
Digisonde DPS 4 replaced the older ionosonde IPS 42 KEL Aerospace in the Observatory Pruhonice in January 2004. Additional information about the wave polarization enables us to determine and to ...
NRGL provides central access to information on grey literature produced in the Czech Republic in the fields of science, research and education. You can find more information about grey literature and NRGL at service web
Send your suggestions and comments to nusl@techlib.cz
Provider
Other bases