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Evaluating drought risk for permanent grasslands under present and future climate conditions
Trnka, Miroslav; Schaumberger, A.; Formayer, H.; Eitzinger, Josef; Hlavinka, Petr; Semerádová, Daniela; Dubrovský, Martin; Možný, M.; Thaler, S.; Žalud, Zdeněk
2011 - English
Over the past years, the changing climate has affected parts of Czech Republic and Austria by drought spells of the intensity and extend that was unprecedented in previous decades. These events had a significant impact on agricultural areas, especially on the grasslands. The idea behind the GIS monitoring relies on hypothesis that the effect of weather and climate conditions on the grassland production can be estimated by models that describe certain natural processes in a simplified manner and in spatialized form.
Keywords:
climatic change; drouhgt stress; grasslands; modelling; yield
Available at various institutes of the ASCR
Evaluating drought risk for permanent grasslands under present and future climate conditions
Over the past years, the changing climate has affected parts of Czech Republic and Austria by drought spells of the intensity and extend that was unprecedented in previous decades. These events had a ...
Statistical analysis of equatorial noise emissions as a function of magnetic local time
Hrbáčková, Zuzana; Němec, F.; Santolík, Ondřej
2011 - English
The four spacecraft of the Cluster mission collect a unique data set since January 2001. We process the time period from January 2001 to December 2009. The spacecraft changed their orbits over the last few years, resulting in the data set with excellent coverage of a wide range of radial distances from the Earth, especially in the equatorial plane. We focus on the statistical analysis of whistler-mode waves called the equatorial noise (EN). These intense wave emissions are generated by unstable ion distributions. They propagate close to the geomagnetic equator at frequencies between the local proton cyclotron frequency and the lower hybrid frequency. Polarization of the magnetic field fluctuations corresponding to these emissions is linear. We processed data from the STAFF-SA instruments which preanalyze data from electric and magnetic field fluctuations onboard and provide us hermitian spectral matrices. We use the data measured at radial distances from about 2 to 11 RE to show the dependence of the occurrence of EN on the magnetic local time (MLT). We show from the statistical analysis that EN is occurred at all research radial distances within 10◦ from the geomagnetic equator and the maximum occurrence rate of EN is during the daytime especially in the afternoon sector.
Keywords:
Cluster spacecraft; Earth's magnetosphere; equatorial noise emission
Available at various institutes of the ASCR
Statistical analysis of equatorial noise emissions as a function of magnetic local time
The four spacecraft of the Cluster mission collect a unique data set since January 2001. We process the time period from January 2001 to December 2009. The spacecraft changed their orbits over the ...
Models of FSO link attenuation due to fog, rain and wind derived from measurement
Fišer, Ondřej; Brázda, Vladimír; Chládová, Zuzana; Pešice, Petr; Svoboda, Jaroslav; Schejbal, V.
2011 - English
The Institute of Atmospheric Physics of the Czech Academy measures atmospheric attenuation on 60 m experimental FSO link while wavelength being 830 and 1550 nm. The measurement lasts three years. In this contribution we show dependences of FSO link attenuation on visibility, rain rate and selected wind parameters. We show that the measured attenuation values are higher than the theoretical values derived by the Kim formula. The sonic temperature is surprisingly very well correlated with attenuation.
Keywords:
Free-space optics; atmospheric attenuation; visibility; rain rate; wind parameters; sonic temperature
Available at various institutes of the ASCR
Models of FSO link attenuation due to fog, rain and wind derived from measurement
The Institute of Atmospheric Physics of the Czech Academy measures atmospheric attenuation on 60 m experimental FSO link while wavelength being 830 and 1550 nm. The measurement lasts three years. In ...
The insoluble particles in water deposited from fog at Milešovka Observatory (Czech Republic)
Bartůňková, Kristýna; Fišák, Jaroslav; Stoyanova, V.; Schoumkova, A.
2011 - English
This study concerns insoluble chemical pollution of fog at Milešovka Observatory in the Czech Republic. In period from August 2006 till July 2007, 25 fog samples at the top of Milešovka Mountain in České Středohoří Mountains were collected by active fog water collector. Water samples were filtered. From 53 to 116 particles from every sample were chosen according to the quantity of particles found in dried filters. Altogether it was more than 2000 particles. Particles were examined with the help of Scanning Electron Microscope and Energy Dispersive X-Ray Spectrometer to distinguish sizes, shapes and composition. After analyzing the data, statistical evaluation was made. Particles were put into categories according to their shapes on spherical and not spherical. Typical particles like Al, Si, K, Fe or Ca-rich particles were determined. Focus was also to particles with rarely represented elements like Ni, Au, Pb, Cu, Zr and Ba. Groups of typical insoluble particles were collated according to meteorological conditions - synoptic situations and wind directions which prevailed in the days of fog events in order to try to find out possible sources of this fog pollution.
Keywords:
Insoluble particles; Scanning Electron Microscope; fog water
Available at various institutes of the ASCR
The insoluble particles in water deposited from fog at Milešovka Observatory (Czech Republic)
This study concerns insoluble chemical pollution of fog at Milešovka Observatory in the Czech Republic. In period from August 2006 till July 2007, 25 fog samples at the top of Milešovka Mountain in ...
Scaling Analysis Applied to Ionospheric, Solar and Geomagnetic Data
Mošna, Zbyšek; Koucká Knížová, Petra
2011 - English
Scaling analysis based on structure function zeta(q) computed using wavelet analysis and spectrum D(h) is used to study possible connection of ionospheric system with the solar and geomagnetic activity. Data from six ionospheric stations (critical frequency foF2), solar flux F10.7 and geomagnetic indices AE, Kp and Dst are used. Data of foF2 show scale invariance in the period range 2–32 day. Scaling properties of ionospheric data show strong dependence on geomagnetic latitude of the station. Similar distribution of values of scaling exponents h for ionospheric and geomagnetic activity AE and Kp suggests connection between these systems. Values of h for foF2 and F10.7 have different distribution which suggests weak connection between these systems at chosen periods.
Keywords:
Scaling analysis; structure function; ionosphere; critical frequencies
Available at various institutes of the ASCR
Scaling Analysis Applied to Ionospheric, Solar and Geomagnetic Data
Scaling analysis based on structure function zeta(q) computed using wavelet analysis and spectrum D(h) is used to study possible connection of ionospheric system with the solar and geomagnetic ...
Automatic Visualization Method of Height–Time Development of Ionospheric Layers
Mošna, Zbyšek; Koucká Knížová, Petra
2010 - English
An automatic method for visualization of variability of ionospheric plasma in terms of ionospheric layers is presented. Here, we use the virtual reflection height for visualization. We directly plot the height–time dependence using original raw digisonde outputs. It gives us an opportunity to promptly visualise the ionospheric digital data and locate events of the interest for further analysis. In this paper, we present a variability in height of E-layer with a special focus on the sporadic E-layer. The proposed method is applicable for any ionospheric region.
Keywords:
Ionospheric Layers; Visualization
Available at various institutes of the ASCR
Automatic Visualization Method of Height–Time Development of Ionospheric Layers
An automatic method for visualization of variability of ionospheric plasma in terms of ionospheric layers is presented. Here, we use the virtual reflection height for visualization. We directly plot ...
Systematic Analysis of Equatorial Noise Using Data of the Cluster Mission
Hrbáčková, Zuzana
2010 - English
The four spacecraft of the Cluster mission are collecting a unique data set. We use data measured between 2002 and 2009. These data are unique not only by their quantity but also because the spacecraft changed their orbits during their operational phase and therefore we have data from a large area around the Earth. We focus our analysis on observations of equatorial noise (EN) which is an intense electromagnetic emission generated by unstable ion distributions. It occurs in the inner magnetosphere and propagates close to the geomagnetic equator between the local proton cyclotron frequency and local lower hybrid frequency. We make systematic analysis of EN using data from the STAFF-SA instruments onboard the four spacecraft of the Cluster mission.
Keywords:
Analysis; Equatorial Noise; Cluster Mission
Available at various institutes of the ASCR
Systematic Analysis of Equatorial Noise Using Data of the Cluster Mission
The four spacecraft of the Cluster mission are collecting a unique data set. We use data measured between 2002 and 2009. These data are unique not only by their quantity but also because the ...
Statistical Study of the Ionospheric Density Variation Related to the 2010 Chile Earthquake and Measured by the DEMETER Satellite
Píša, David; Santolík, Ondřej; Parrot, M.
2010 - English
Statistical Study of the Ionospheric Density Variation Related to the 2010 Chile Earthquake and Measured by the DEMETER Satellite.
Keywords:
Whistler-mode Chorus; Emissions
Available at various institutes of the ASCR
Statistical Study of the Ionospheric Density Variation Related to the 2010 Chile Earthquake and Measured by the DEMETER Satellite
Statistical Study of the Ionospheric Density Variation Related to the 2010 Chile Earthquake and Measured by the DEMETER Satellite.
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 - English
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.
Keywords:
Solar Radio; SVD; Wavelengths; STEREO
Available at various institutes of the ASCR
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 - English
Different Spectral Shapes of Whistler-mode Chorus Emissions are presented here.
Keywords:
Whistler-mode Chorus; Emissions
Available at various institutes of the ASCR
Different Spectral Shapes of Whistler-mode Chorus Emissions
Different Spectral Shapes of Whistler-mode Chorus Emissions are presented here.
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