Number of found documents: 189
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Measurements of electromagnetic signals generated by lightning and atmospheric discharges associated with transient luminous events
Zemanová, Hana; Santolík, Ondřej; Kolmašová, Ivana
2016 - English
This paper focuses on the measurement techniques of extremely low\nfrequency EM waves generated by lightning. Basic types of lightning and transient\nluminous events along with the definition and properties of Schumann resonance are\npresented. We also show the description of our measurement site in Nov´y Kostel,\nwhich uses one horizontal magnetic antenna.\n Keywords: magnetosphere; lightning; extremely low frequency waves (ELF); transient luminous events; Schumann resonance; Novy Kostel Available at various institutes of the ASCR
Measurements of electromagnetic signals generated by lightning and atmospheric discharges associated with transient luminous events

This paper focuses on the measurement techniques of extremely low\nfrequency EM waves generated by lightning. Basic types of lightning and transient\nluminous events along with the definition and ...

Zemanová, Hana; Santolík, Ondřej; Kolmašová, Ivana
Ústav fyziky atmosféry, 2016

HF Doppler Observations of Ionospheric Disturbances over Taiwan
Fišer, Jiří; Chum, Jaroslav
2015 - English
Results of observations of traveling ionospheric disturbances (TIDs) by the multipath continuous HF Doppler sounding system operating in Taiwan are presented. We analysed one-year long period of measurements from April 2014 to March 2015 and investigated horizontal velocities and azimuths of propagation of medium scale traveling ionospheric disturbances (MSTIDs) with periods from 4 min to 60 min. Horizontal velocities range from ≈ 100 m s−1 to ≈ 300 m s−1 and MSTIDs propagate preferentially south-eastward in the local winter and preferentially northward in the local summer. The disturbances rarely propagate with azimuth in the range of 200–290◦ . Keywords: traveling ionospheric disturbances; ionosphere; HF Doppler sounding Available at various institutes of the ASCR
HF Doppler Observations of Ionospheric Disturbances over Taiwan

Results of observations of traveling ionospheric disturbances (TIDs) by the multipath continuous HF Doppler sounding system operating in Taiwan are presented. We analysed one-year long period of ...

Fišer, Jiří; Chum, Jaroslav
Ústav fyziky atmosféry, 2015

Comparison of parametric methods for radar signal processing
Rejfek, Luboš; Burešová, Dalia; Fišer, O.; Brázda, V.
2015 - English
The paper deals with comparison of parametric power spectral density methods for the utilization in the meteorological radar (pulse radar of frequency modulated pulses). We have compared duration of signal processing requested by single methods involved in the test. The methods used are the Auto Regressive model, MUSIC method, Eigen Vector algorithm and CAPON. The best results we have obtained for the AR model. Keywords: PSD method; MUSIC; Eigen Vector algorithm; CAPON; Auto Regressive (AR) model; frequency modulated radar Available at various institutes of the ASCR
Comparison of parametric methods for radar signal processing

The paper deals with comparison of parametric power spectral density methods for the utilization in the meteorological radar (pulse radar of frequency modulated pulses). We have compared duration of ...

Rejfek, Luboš; Burešová, Dalia; Fišer, O.; Brázda, V.
Ústav fyziky atmosféry, 2015

Automated eddy covariance data quality control for long-term measurements
Šigut, L.; Mauder, M.; Sedlák, Pavel; Pavelka, M.; Špunda, V.
2015 - English
Estimation of matter and energy exchange using the eddy covariance method is often organized into regional or global networks. To achieve comparability among sites, it is important to standardize and specify the methodology used. Currently, quality control (QC) is one of the most time-demanding steps in data processing within the Czech Carbon Observation System. Although manual QC (MQC) enables consideration of more complex test applications, it is often difficult to document. The aim of this study was to establish an automated QC (AQC) scheme based on available literature and post-processing software and test its effectivity and reliability on sites comprising an agroecosystem and a mature European beech forest. AQC successfully flagged low-quality CO2 fluxes and provided estimates of net ecosystem productivity similar to estimates based on MQC. The tests’ efficiency was particularly high for the agroecosystem, where AQC removed 13% less data than did MQC. We conclude that the adopted AQC displays satisfactory performance, especially for sites with low canopy heights. Keywords: eddy covariance; data quality control Available at various institutes of the ASCR
Automated eddy covariance data quality control for long-term measurements

Estimation of matter and energy exchange using the eddy covariance method is often organized into regional or global networks. To achieve comparability among sites, it is important to standardize and ...

Šigut, L.; Mauder, M.; Sedlák, Pavel; Pavelka, M.; Špunda, V.
Ústav fyziky atmosféry, 2015

Comparision of devices for monitoring of the ionosphere at the observatory Průhonice
Beran, L.; Chmelař, P.; Rejfek, Luboš; Chum, Jaroslav; Mošna, Zbyšek
2015 - English
This document is about comparison of the methods ad systems for the measurement of the ionosphere used at the geophysical observatory Pruhonice (50N, 14.5E). Three systems for ionospheric monitoring are installed at the station. The first system for the monitoring of the ionosphere is Digisonde, the second system is countinuous Doppler sounding. Each system has its banefits and weaknesses which are compared in this paper. Keywords: digisonde; GNSS receiver; continuous Doppler sounding; ionosphere; Total Electron Content (TEC) Available at various institutes of the ASCR
Comparision of devices for monitoring of the ionosphere at the observatory Průhonice

This document is about comparison of the methods ad systems for the measurement of the ionosphere used at the geophysical observatory Pruhonice (50N, 14.5E). Three systems for ionospheric monitoring ...

Beran, L.; Chmelař, P.; Rejfek, Luboš; Chum, Jaroslav; Mošna, Zbyšek
Ústav fyziky atmosféry, 2015

Drivers of soil moisture trends in the Czech Republic between 1961 and 2012
Trnka, M.; Brázdil, R.; Balek, J.; Semerádová, D.; Hlavinka, P.; Možný, M.; Štěpánek, P.; Dobrovolný, P.; Zahradníček, P.; Dubrovský, Martin; Eitzinger, J.; Fuchs, B.; Svoboda, M.; Hayes, M.; Žalud, Z.
2015 - English
Soil moisture dynamics and their temporal trends in the Czech Republic are forced by various drivers. Our analysis of temporal trends indicates that shifts in drought severity between 1961 and 2012 and especially in the April, May, and June period, which displayed such results as a 50% increase in drought probability during 1961–1980 in comparison to 2001–2012. We found that increased global radiation and air temperature together with decreased relative humidity (all statistically significant at p < 0.05) led to increases in the reference evapotranspiration in all months of the growing season; this trend was particularly evident in April, May, and August, when more than 80% of the territory displayed an increased demand for soil water. These changes, in combination with the earlier end of snow cover and the earlier start of the growing season (up to 20 days in some regions), led to increased actual evapotranspiration at the start of the growing season that tended to deplete the soil moisture earlier, leaving the soil more exposed to the impacts of rainfall variability. These results support concerns related to the potentially increased severity of drought events in Central Europe. The reported trend patterns are of particular importance with respect to expected climate change, given the robustness and consistency of the trends shown and the fact that they can be aligned with the existing climate model projections. Introduction Keywords: soil moisture; Czech Republic; climate change Available at various institutes of the ASCR
Drivers of soil moisture trends in the Czech Republic between 1961 and 2012

Soil moisture dynamics and their temporal trends in the Czech Republic are forced by various drivers. Our analysis of temporal trends indicates that shifts in drought severity between 1961 and 2012 ...

Trnka, M.; Brázdil, R.; Balek, J.; Semerádová, D.; Hlavinka, P.; Možný, M.; Štěpánek, P.; Dobrovolný, P.; Zahradníček, P.; Dubrovský, Martin; Eitzinger, J.; Fuchs, B.; Svoboda, M.; Hayes, M.; Žalud, Z.
Ústav fyziky atmosféry, 2015

Chování ionosférických driftů během superbouře v listopadu 2004
Kouba, Daniel
2014 - Czech
V tomto článku jsou prezentovány výsledky získané zpracováním driftových měření ve vrstvé F ionosféry ze stanice Průhonice. Tyto výsledky lze rozdělit do dvou částí - zkoumání pravidelného chování klidné ionosféry a demonstraci chování ionosféry během silné geomagnetické bouře. Za pravidelné chování lze považovat denní a sezónní variace i variace odpovídající slunečnímu cyklu. Chování ionosféry za klidných podmínek je důležité znát z důvodu studia vlivu vybraných událostí. Těmi mohou být geomagnetické bouře, zatmění Slunce, přechody výrazných meteorologických front apod. V článku jsou shrnuty některé výsledky popsané v disertační práci [Kouba, 2014]. Pokud bude známo chování driftů za klidných podmínek i během různých poruch ionosféry, bude v budoucnu možno realizovat i předpovědi dynamiky ionosférických vrstev. This article presents results obtained by processing the measurement drift in the F layer of the ionosphere from the Pruhonice observatory.Diurnal and seasonal behaviour of the ionosphere is examined. The effect of strong geomagnetic storms on the ionosphere is presented. Keywords: ionospheric F-layer; geomagnetic storm; drift measurements Available at various institutes of the ASCR
Chování ionosférických driftů během superbouře v listopadu 2004

V tomto článku jsou prezentovány výsledky získané zpracováním driftových měření ve vrstvé F ionosféry ze stanice Průhonice. Tyto výsledky lze rozdělit do dvou částí - zkoumání pravidelného chování ...

Kouba, Daniel
Ústav fyziky atmosféry, 2014

Geomagnetická aktivita a její vliv na ionosféru
Mošna, Zbyšek; Koucká Knížová, Petra
2014 - Czech
Cl anek se zab yv a vazbou geomagnetick e aktivity na ionosf eru. Je pops an mechanismus pusoben poru sen eho meziplanetarního pole slune cn ho v etru na zemsk e magnetick e pole v r uzn ych oblastech (vysok e a n zk e s rky). V praktick e c asti jsou prezentov any v ysledky m e ren z vertik aln ho ionosf erick eho sondov an v obdob geomagneticky poru sen e situace z oblasti st redn ch s rek ze stanice Pr uhonice. Je uk az an pokles maxim aln elektronov e koncentrace a zm ena v y sek vrstvy F2. Keywords: ionosféra; geomagnetická aktivita Available at various institutes of the ASCR
Geomagnetická aktivita a její vliv na ionosféru

Cl anek se zab yv a vazbou geomagnetick e aktivity na ionosf eru. Je pops an mechanismus pusoben poru sen eho meziplanetarního pole slune cn ho v etru na zemsk e magnetick e pole v r uzn ych ...

Mošna, Zbyšek; Koucká Knížová, Petra
Ústav fyziky atmosféry, 2014

HF Doppler Radar Observations of Geomagnetic Pulsations
Fišer, Jiří; Chum, Jaroslav
2014 - English
Geomagnetic pulsations interact with the ionosphere, which influences the propagation properties of high frequency (HF) radio waves. In this work we present results of an experimental study focused on investigation of relations between the geomagnetic pulsations observed on the ground and the Doppler frequency shift oscillations observed remotely in the ionosphere by a Doppler sounding system in the Czech Republic. We study mainly the dependence of phase shift between them on various parameters. Keywords: Doppler sounding; ionosphere; geomagnetic pulsations Available at various institutes of the ASCR
HF Doppler Radar Observations of Geomagnetic Pulsations

Geomagnetic pulsations interact with the ionosphere, which influences the propagation properties of high frequency (HF) radio waves. In this work we present results of an experimental study focused ...

Fišer, Jiří; Chum, Jaroslav
Ústav fyziky atmosféry, 2014

Akusticko-gravitační, přílivové a planetární vlny v ionosféře
Koucká Knížová, Petra; Mošna, Zbyšek; Potužníková, Kateřina
2014 - Czech
Neutrální atmosféra je důležitým faktorem ovlivňujícím stav ionosféry. Analyzujeme vliv vln v oblasti period minuty (akustické vlny) až dny (planetární vlny). Neutral atmosphere affects strongly the ionosphere. We study influence of the neutral wave activity on the ionosphere in range of periods from minutes to days (acoustic waves to planetary waves). Keywords: acoustic waves; gravity waves; vertical coupling Available at various institutes of the ASCR
Akusticko-gravitační, přílivové a planetární vlny v ionosféře

Neutrální atmosféra je důležitým faktorem ovlivňujícím stav ionosféry. Analyzujeme vliv vln v oblasti period minuty (akustické vlny) až dny (planetární vlny)....

Koucká Knížová, Petra; Mošna, Zbyšek; Potužníková, Kateřina
Ústav fyziky atmosféry, 2014

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