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Public RPWS/HFR data Browse ReadMe
This page provides a tool to visualize dynamic spectra (or time-frequency diagrams) of RPWS/HFR processed data. Each dynamic spectrum scans an interval of one day (24h), whose limits can be changed by clicking directly on the Figure.
Data description
Dynamic spectra are expressed in four different quantities (to be chosen in the up right drop list):
  • Raw power spectral density
    Electric power (in arbitrary units) recorded by one monopole or the dipole (formed by two monopoles) over the entire RPWS/HFR frequency range (3.5kHz to 16.125MHz).
  • Raw power spectral density with background subtracted
    Same as above, except that a background, daily computed for each frequency, has been subtracted. This emphasizes the dynamics of observed radio signals.
  • Spectral Flux Density (S)
    Magnitude of the Poynting vector computed by a goniopolarimetric inversion using 2 antennas [1]. The spectral range is limited between 3.5 and 1500kHz, covering the low frequency emissions and SKR spectral ranges. For convenience, it is expressed in units of W/m2/Hz and normalized to 1 AU to define a fixed intensity scale [2]. Note that this quantity is usually referred to as the Stokes parameter S or I.
    Caveats
    - S being computed from 2-antenna measurements, and assuming a circular polarization, its value may depend on the orientation of both antennas with respect to the wave vectors in case they are not circularly polarized [1,3].
    - The flux normalization is applied to all available samples, resulting in artificially enhanced background levels when far from Saturn (e.g., at the begining of 2004).
  • Circular polarization degree (V)
    Normalized degree of circular polarization (or Stokes parameter V), varying between -1 (right-handed - RH - polarized, white) and +1 (left-handed - LH - polarized, black). SKR being mainly emitted on the extraordinary mode [2], RH (LH respec.) corresponds to emission emanating from the northern (southern respec.) hemisphere.
    Caveat
    The goniopolarimetric inversion used to compute V also relies on the geometric orientation of the antennas with respect to the observed wave vectors. Erratic values of V may be observed during fast spacecraft roll maneuvers.
    switch arrow Click here for an example
Data are available from 2004001 to 2010235.
Options
This tool includes the possibility to overplot the predicted phase of SKR bursts (click in the corresponding option) with two different longitude systems: the SLS3 model [4,5] and the Northern/Southern empirical phase detailed on this page.
References
[1] Cecconi and Zarka, 2005. [link]
[2] Lamy et al., 2008. [link]
[3] Fischer et al., 2009. [link]
[4] Kurth et al, GRL, 2007. [link]
[5] Kurth et al, JGR, 2008. [link]
Contact
For any question: please contact the webmaster.
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