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Systematic Analysis of Equatorial Noise Using Data of the Cluster Mission
Hrbáčková, Zuzana
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.
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Automatic Visualization Method of Height–Time Development of Ionospheric Layers
Mošna, Zbyšek ; Koucká Knížová, Petra
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.
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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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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.
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.
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