Změny profilů elektronové koncentrace a TEC v průběhu vysoké sluneční aktivity
Boška, Josef; Mošna, Zbyšek
2014 - Czech Keywords: geomagnetic storm; ionospheric storm; total electron content Available at various institutes of the ASCR Změny profilů elektronové koncentrace a TEC v průběhu vysoké sluneční aktivity

Boška, Josef; Mošna, Zbyšek
Ústav fyziky atmosféry, 2014

Device for Measurement of Optical Visibility
Rejfek, L.; Brázda, V.; Fišer, Ondřej
2013 - English This paper is about a proposed device for the optical visibility measurement. This device is usable for monitoring of the fog mightiness. The principle of device is based on comparison of attenuation on two optical links. The fog mightiness is determined by the using of the Beer-Lambert Law. The philosophy of electrical arrangement is also explained. Keywords: Beer-Lambert Law; Optical Links; Optical Visibility; Mightiness of the Fog; Absorbance; Transmittance Available at various institutes of the ASCR Device for Measurement of Optical Visibility

This paper is about a proposed device for the optical visibility measurement. This device is usable for monitoring of the fog mightiness. The principle of device is based on comparison of ...

Rejfek, L.; Brázda, V.; Fišer, Ondřej
Ústav fyziky atmosféry, 2013

Subseasonal temperature trends in Europe (1961-2000) and their links to atmospheric circulation
Cahynová, Monika; Pokorná, Lucie
2013 - English We use daily maximum and minimum temperatures and the daily temperature range from 136 stations in Europe in the period 1961–2000 to precisely locate their seasonal and subseasonal trends within the year. Linear trends are calculated for moving “subseasons” of 10, 20, 30, 60, and 90 days, each shifted by one day. Over most of Europe, the observed warming is greatest in winter. In Iceland and the Mediterranean, a pronounced warming is only present in summer. Significant autumn cooling was found in Eastern and Southeastern Europe for both TX and TN. Other non-warming periods occur in Western and Central Europe in February, April, and late June. Trends of DTR are inconclusive. Changes in the frequency of atmospheric circulation types usually explain a substantial part of the observed climatic trends; however, the influence varies between regions, times of the year, subseason lengths, numbers of circulation types, and input variables for the classification of circulation types. Keywords: air temperature; daily temperature range; trend; atmospheric circulation; classification Available at various institutes of the ASCR Subseasonal temperature trends in Europe (1961-2000) and their links to atmospheric circulation

We use daily maximum and minimum temperatures and the daily temperature range from 136 stations in Europe in the period 1961–2000 to precisely locate their seasonal and subseasonal trends within the ...

Cahynová, Monika; Pokorná, Lucie
Ústav fyziky atmosféry, 2013

Vliv nově vzniklé jezerní plochy na mikroklima
Bartůňková, Kristýna; Sokol, Zbyněk
2013 - Czech Příspěvek se zabývá vlivem nově vzniklé jezerní plochy na lokální klima. Je motivován napuštěním antropogenního jezera Most na místě bývalého lomu Ležáky v severních Čechách. Vlivy na mikroklima, způsobené změnami ve fyzicko-geografických charakteristikách lokality, jsou zkoumány pomocí idealizovaných výpočtů numerického modelu COSMO, jehož součástí je také model jezera FLake. Vstupní přízemní data jsou získána měřením na meteorologické observatoři Kopisty a na stanici na jezeře, která měří rovněž teplotu vody v 16 vertikálních profilech až do hloubky 20 m. Pro popis vertikálního profilu atmosféry jsou využity analýzy meteorologických polí z Evropského střediska pro střednědobou předpověď (ECMWF). Z prvních výsledků vyplývá, že velká jezera zřetelně ovlivňují přízemní teplotu vzduchu v zimních a především v letních měsících, kdy za určitých meteorologických situací způsobují ochlazení vzduchu při zemském povrchu o více než 2°C. Se zvyšující se vzdáleností od zemského povrchu pochopitelně vliv jezera klesá. V horizontální rovině je vliv na změnu teploty patrný do vzdálenosti cca 3 km. In this contribution the impact of new water area on local climate is studied. The area of interest is newly originated lake Most in northern Bohemia. The impacts on microclimate that are evoked by physic-geographical changes in the area are studied by the help of the NWP model COSMO. The part of this model is Lake Model FLake. Input data are measured at the meteorological observatory Kopisty and at the lake station that measures also the water temperature in 16 vertical levels to the depth of 20 m. First results show significant influence of lake existence on air temperature, especially in summer months (June, July and August). The maximum influence is 1.2°C cooling in the surface level of the atmosphere. With the rising distance from the surface the impact on air temperature is decreasing. Keywords: lake; microclimate; numerical modeling; COSMO Available at various institutes of the ASCR Vliv nově vzniklé jezerní plochy na mikroklima

Příspěvek se zabývá vlivem nově vzniklé jezerní plochy na lokální klima. Je motivován napuštěním antropogenního jezera Most na místě bývalého lomu Ležáky v severních Čechách. Vlivy na mikroklima, ...

Bartůňková, Kristýna; Sokol, Zbyněk
Ústav fyziky atmosféry, 2013

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 ...

Lhotka, Ondřej; Kyselý, Jan
Ústav fyziky atmosféry, 2013

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 ...

Fišer, O.; Rejfek, Luboš; Brázda, Vladimír
Ústav fyziky atmosféry, 2013

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 ...

Hrbáčková, Zuzana; Santolík, Ondřej
Ústav fyziky atmosféry, 2012

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 ...

Brázda, V.; Schejbal, V.; Fišer, Ondřej
Ústav fyziky atmosféry, 2012

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 ...

Krupař, Vratislav; Cecconi, B.; Maksimovic, M.; Nguyen, Q. N.; Santolík, Ondřej
Ústav fyziky atmosféry, 2011

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 ...

Fišák, Jaroslav; Bartůňková, Kristýna
Ústav fyziky atmosféry, 2011