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Estimation of the Apparent Source Size of Solar Radio Emissions Using SVD: An Application to Type III Radio Bursts at Long Wavelengths Observed by STEREO and Wind
Krupař, Vratislav; Santolík, Ondřej; Cecconi, B.; Maksimovic, M.
2010 - anglický
Type III radio bursts are intense solar radio emissions. They are frequently observed by the S/Waves instruments on-board the STEREO spacecraft. We describe a wave propagation analysis using the Singular Value Decomposition (SVD) which can be directly applied to spectral matrices measured by the High Frequency Receiver (HFR; a part of the S/Waves experiment). We have found an empirical relation between the decomposed spectral matrices and apparent source sizes for waves with a low degree of polarization. We present a joint observation of a type III radio burst by the STEREO and Wind spacecraft during small separation distances. We obtain consistent results for the apparent source size and k-vector direction using different analysis method for the measurements of the STEREO and Wind spacecraft. We demonstrate that SVD can be an effective tool for the wave analysis of radio emissions with very extended sources.
Klíčová slova:
Solar Radio; SVD; Wavelengths; STEREO
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Estimation of the Apparent Source Size of Solar Radio Emissions Using SVD: An Application to Type III Radio Bursts at Long Wavelengths Observed by STEREO and Wind
Type III radio bursts are intense solar radio emissions. They are frequently observed by the S/Waves instruments on-board the STEREO spacecraft. We describe a wave propagation analysis using the ...
Different Spectral Shapes of Whistler-mode Chorus Emissions
Macúšová, Eva; Santolík, Ondřej
2010 - anglický
Different Spectral Shapes of Whistler-mode Chorus Emissions are presented here.
Klíčová slova:
Whistler-mode Chorus; Emissions
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Different Spectral Shapes of Whistler-mode Chorus Emissions
Different Spectral Shapes of Whistler-mode Chorus Emissions are presented here.
Study of Chance for Good DDA Drift Velocity Estimation for Ionospheric F-region Drift Measurements
Kouba, Daniel; Koucká Knížová, Petra
2010 - anglický
Estimation of the plasma drift velocity measured by Digisonde depends on the number of reflection points and their distribution. In the paper we divide and analyse plasma drift measurements according to the number of reflection points. A detailed study of Digisonde drift measurement quality has not been published yet. Two extreme groups are selected for further detail analysis, the first one with less than 100 reflection points and the second with more than 800 points. Within the data in these groups we detect annular and diurnal variability. Measurements containing low number of the reflection points occur mainly around equinoxes and during day-time. On the contrary, maximum occurrence of the measurements with more than 800 points is in winter and summer. The lowest chance to register extreme number of the reflections is during afternoon and around sunset.
Klíčová slova:
Drift Velocity; DDA; Estimation; F-region
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Study of Chance for Good DDA Drift Velocity Estimation for Ionospheric F-region Drift Measurements
Estimation of the plasma drift velocity measured by Digisonde depends on the number of reflection points and their distribution. In the paper we divide and analyse plasma drift measurements according ...
Calibration of the STEREO/WAVES Instrument in the Solar Wind
Krupař, Vratislav; Maksimovic, M.; Cecconi, B.; Santolík, Ondřej
2009 - anglický
The S/WAVES instrument onboard the STEREO spacecraft measures electromagnetic waves in the solar wind. This unique project allows us to investigate properties of type II and type III radio bursts related with solar flares and propagation of coronal mass ejections (CMEs) in the interplanetary medium, respectively. In this paper we present properties of the High Frequency Receiver (HFR) receiver which covers the frequency range 125 kHz–16.025 MHz. We have compared the gains from the two HFR channels and we have found significant variations of these gains with time. We have proposed a solution for correcting these gain variations and improving the S/WAVES HFR calibrations in order to get as accurate goniopolarimetric measurements as possible.
Klíčová slova:
Solar Radio Emissions; Goniopolarimetric inversion
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Calibration of the STEREO/WAVES Instrument in the Solar Wind
The S/WAVES instrument onboard the STEREO spacecraft measures electromagnetic waves in the solar wind. This unique project allows us to investigate properties of type II and type III radio bursts ...
Total Electron Content Measurement Using Digisonde and GNSS
Kouba, Daniel; Šauli, Petra
2009 - anglický
The digital pulse ionospheric sounder (Digisonde) of the University of Massachusetts Lowell has been operated in Pruhonice (geographic coordinates 50.0N, 14.6E) since 2004 for ionospheric study. Earlier, KEL Aerospace and ISP-42 ionosondes had also been operated. Hence, there is a long archive of bottomside ionospheric records for a period of about sixty years. In 2009, Topcon NET-G3 triple frequency Global Navigation Satellite System receiver will also be installed at the station, collocated with the Digisonde. GNSS receivers are becoming recognized as another source for ionospheric information. This year, the upgrade of Digisonde DPS-4 to model DPS-4D also will be realized. This new type will provide a much wider usage and expands the possibilities of our research. The GNSS and Digisonde measurements jointly will bring new improvements to the models of electron density profiles.
Klíčová slova:
ionosphere; ionogram; TEC mapping
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Total Electron Content Measurement Using Digisonde and GNSS
The digital pulse ionospheric sounder (Digisonde) of the University of Massachusetts Lowell has been operated in Pruhonice (geographic coordinates 50.0N, 14.6E) since 2004 for ionospheric study. ...
Database of Whistler-mode Chorus in the Equatorial Plane
Macúšová, E.; Santolík, Ondřej
2009 - anglický
Chorus emission is one of the most intense electromagnetic waves. Its source region is localised close to the geomagnetic equatorial plane within a few degrees. We present a unique database of whistler-mode chorus/hiss events obtained from the complete data set of wave measurements provided by the STAFF/DWP wave instrument on board TC-1 spacecraft. The TC-1 is one of two Earth orbiting satellites from the Double Star mission and it orbits close to the equatorial plane. Some instruments onboard both spacecraft are identical to those currently flying on the four Cluster spacecraft. The data base covers the full operational period of the spacecraft, between January 2004 and October 2007. All the events have been visually selected from the onboard-analyzed time-frequency spectrograms of magnetic search-coil measurements below 4 kHz.
Klíčová slova:
Database; Whistler-mode; Chorus; Equatorial; Plane
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Database of Whistler-mode Chorus in the Equatorial Plane
Chorus emission is one of the most intense electromagnetic waves. Its source region is localised close to the geomagnetic equatorial plane within a few degrees. We present a unique database of ...
Ionospheric response to the particular solar event as seen in the ionospheric vertical sounding
Mošna, Zbyšek; Koucká Knížová, Petra; Georgieva, K.
2009 - anglický
Two types of solar events (Coronal Mass Ejections -CMEs and their subset with rotational magnetic field, Magnetic Clouds - MCs and High Speed Solar Stream –HSS) are mainly responsible for geomagnetic and ionospheric (geospheric) disturbances. Three solar events from year 2004 were chosen and ionospheric responses by means of foF2 and h'F2 were studied.
Klíčová slova:
geoeffectivity; critical frequency foF2; virtual height h’F2; Magnetic Cloud; High Speed Solar Stream; digisonde
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Ionospheric response to the particular solar event as seen in the ionospheric vertical sounding
Two types of solar events (Coronal Mass Ejections -CMEs and their subset with rotational magnetic field, Magnetic Clouds - MCs and High Speed Solar Stream –HSS) are mainly responsible for geomagnetic ...
Analysis of Climate Model Outputs Using Linear and Nonlinear Statistical Techniques
Chládová, Zuzana
2009 - anglický
Regional climate models (RCMs) are currently one of regularly applied tools for localization of global climate models (GCMs) outcomes. This study is focused on analyses of mean daily temperature and precipitation using linear and nonlinear statistical techniques. 48 grid points of the regional climate models HIRHAM and RCAO and 29 meteorological stations of the Czech Republic were compared in the period 1961-1990. Mean annual courses of mean daily temperature and precipitation in the period 2071-2100 were analyzed at selected HIRHAM and RCAO grid points for A2 and B2 emission scenarios [IPCC, 2007]. Furthermore, time-delayed average mutual information (AMI) and autocorrelation function were analyzed. AMI and autocorrelation function were calculated for one selected time series of each grid point of the Czech Republic and Europe with a time lag varying from 1 to 10 days. The values of average mutual information were compared with values of autocorrelation function. Globální a regionální klimatické modely jsou v současnosti nejdůležitějšími nástroji při vytváření projekcí budoucího klimatu. V rámci předkládané práce byla provedena analýza schopnosti klimatických modelů modelovat budoucí klima pomocí lineárních a nelineárních statistických technik. Konkrétně byly porovnávány zvolené referenční a budoucí běhy regionálních klimatických modelů RCAO a HIRHAM na území České republiky. Pro 48 uzlových bodů těchto regionálních klimatických modelů a 29 meteorologických stanic na území České republiky byly porovnávány roční chody průměrné denní teploty a srážek pro období 1961–1990. Pro uzlové body byly sledovány roční chody průměrné denní teploty a srážek podle scénářů A2 a B2 pro období 2071–2100. V další části práce byla provedena analýza pomocí časově zpožděné míry vzájemné informace (MVI) a autokorelační funkce s časovým posunem od jednoho do deseti dní. Prostorové rozložení MVI bylo vyhodnoceno pro evropský kontinent se zaměřením na území České republiky.
Klíčová slova:
RCMs; GCMs; Czech Republic; mean daily temperature; precipitation
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Analysis of Climate Model Outputs Using Linear and Nonlinear Statistical Techniques
Regional climate models (RCMs) are currently one of regularly applied tools for localization of global climate models (GCMs) outcomes. This study is focused on analyses of mean daily temperature and ...
Analysis of heavy elements in air, fog and rime from Milesovka and Kopisty
Stoyanova, V.; Petrova, P.; Fišák, Jaroslav; Daskalova, N.; Tsacheva, Ts.; Marinov, M.
2008 - anglický
Aim of this study is to estimate the presence of heavy metal particles filter-collected in the air, fog and rime water from the polluted area of North Bohemia, Czech Republic. The proposed comparison of the obtained preliminary results for air born particles enriched of heavy metals with those captured in the fog and rime, combined with a comparative analysis of water-soluble and insoluble particles from the same samples (Fišák et al. 2007, 2008), could provide a basis for the most appropriate way for future analyzing of many other samples in similar routine manner. Cílem této studie je zhodnotit výskyt částiček těžkých kovů ve vzorcích získaných filtrováním vzduchu, vody z mlh a námraz ze znečištěné oblasti Severních Čech. Uskutečněné porovnání představuje předběžné výsledky částic obsažených ve vzduchu obsahujících těžké kovy zachycených v mlze a námraze. Spolu se srovnávací analýzou ve vodě rozpustných a nerozpustných částic ve stejných vzorcích (Fišák et al. 2007, 2008), může posloužit jako vhodný způsob pro následující analýzy dalších podobných vzorků.
Klíčová slova:
fog-water; rime-water; soluble and insoluble components; electron analysis
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Analysis of heavy elements in air, fog and rime from Milesovka and Kopisty
Aim of this study is to estimate the presence of heavy metal particles filter-collected in the air, fog and rime water from the polluted area of North Bohemia, Czech Republic. The proposed comparison ...
2-year results of hydrometeor attenuation research at 93 GHz on an 850 m terrestrial path
Kvičera, V.; Grábner, M.; Fišer, Ondřej
2008 - anglický
The results of 2 years of experimental research of attenuation due to hydrometeors at 94 GHz with V polarization on an 850 m path are presented. Both the cumulative distributions of attenuation due to all the hydrometeors together and the cumulative distributions of attenuation due to the individual hydrometeors are given. The results are compared with the relevant ITU-R recommendations. Výsledky dvouletého výzkumu útlumu způsobeného hydrometeory na trase 93 GHz (V polarizace) a v optickém pásmu 850 nm jsou prezentovány ve formě distribučních křivek. Odpovídají buďto totálnímu útlumu nebo útlumu podle jednotlivých typů hydrometeorů. Výsledky jsou porovnány s doporučeními ITU-R.
Klíčová slova:
electromagnetic wave propagation; attenuation; attenuation due to hydrometeors; hydrometeors; propagation characteristics
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
2-year results of hydrometeor attenuation research at 93 GHz on an 850 m terrestrial path
The results of 2 years of experimental research of attenuation due to hydrometeors at 94 GHz with V polarization on an 850 m path are presented. Both the cumulative distributions of attenuation due ...
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