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Calibration of the STEREO/WAVES Instrument in the Solar Wind
Krupař, Vratislav ; Maksimovic, M. ; Cecconi, B. ; Santolík, Ondřej
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.
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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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Analýza kritických frekvencí v ionosféře
Mošna, Zbyšek ; Šauli, Petra ; Santolík, Ondřej
Ionosféra je vysoce proměnlivý systém. Pro popis ionosféry se často používají kritické frekvence, které udávají maximální elektronovou koncentraci v dané ionosférické vrstvě. Ionosféra, podobně jako mnoho dalších přírodních systémů, vykazuje scaling vlastnosti. V tomto článku jsou uvedeny výsledky scaling analýzy z ionosférických dat ze stanice Průhonice, geomagnetických dat a dat sluneční aktivity z let 1957-2005.
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