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Study of Chance for Good DDA Drift Velocity Estimation for Ionospheric F-region Drift Measurements
Kouba, Daniel ; Koucká Knížová, Petra
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.
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Analýza kritických frekvencí v ionosféře
Mošna, Zbyšek ; Šauli, Petra ; Santolík, Ondřej
Ionosphere is a highly variable system. The most used way how to describe the state of ionosphere is to deal with the critical frequencies which directly reflect the maximum electron concentration in an ionospheric layer. Ionosphere, like many natural systems, exhibits scaling properties. In this paper, we show results of the scaling analysis of ionospheric data from Pruhonice observatory, geomagnetic, and solar flux data from 1957-2005.
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Příprava databáze pro studii škálovacích fenoménů v ionosféře
Mošna, Zbyšek ; Šauli, Petra ; Santolík, Ondřej
The correct forecast of the state of the ionosphere requires understanding of all the effects which influence its behaviour as well as the extent of the relationships in the system. A convenient way how to analyse large data sets and describe the coupling or disconnection at various time scales is to study the scaling phenomena. For the computations of scaling properties of the processes that influence the ionosphere dynamics we have prepared a database of several characteristics that describe the coupling processes in the solar-magnetosphere-ionosphere system. This data are of sufficient length and sampling density to verify the presence or absence of links between the processes under study.
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Analysis of turbulent flow over forested terrain
Potužníková, Kateřina ; Sedlák, Pavel ; Šauli, Petra
The aim of the present study is to assess and describe low-frequency oscillations and coherent structures in temporal series of temperature and wind velocity components sampled at three different levels within the forest (z/h = 0.3, 0.5 and 1, where h is the canopy height). The wavelet transform is used as a basic tool for our analysis. The periods of detected structures depend on the temperature gradient in the canopy, and furthermore seem to vary with the different local circulations regimes.
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Scale invariance in the ionosphere
Šauli, Petra ; Abry, P. ; Cosson, X. ; Roux, S.
Scaling invariance domains represent domains where no preferential period of oscillation exists. Scaling laws always reveal an important property of the analysed system: self-similarity or multifractality. The observed ground-based and satellite ionospheric time series contain a mix of fluctuations of different physical origin (solar, geomagnetic, neutral atmosphere variability etc.). Description based on scaling features can be applied in the solar wind-magnetosphere-ionosphere interaction studies for further comparison of basic characteristics of intermittent fluctuations in solar wind, magnetosphere and ionosphere systems. Finding the similar scaling features of the solar and geomagnetic data in the ionospheric response might be a signature of common nature of the observed fluctuations. A comprehensive understanding of the scaling properties of the ionospheric indices has relevance for the predictability of the behaviour of the ionosphere within specified time range.
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