POLAR Plasma Wave Investigation (PWI) Multichannel Analyzer (MCA) Survey Spectrograms

The Polar PWI Multichannel Analyzer (MCA) collected data from March 1996 to September 1997. The MCA data has very good time resolution (~1 s) but relatively poor frequency resolution. An electric field measurement covers 5.6 Hz to 311 kHz in 20 channels logarithmically spaced. The magnetic field measurements cover a range from 5.6 Hz to 10 kHz in 14 channels logarithmically spaced. Each file consists of two plots. Each plot contains the power spectral density (color scale) of received signal (upper plot: electric (V^2 m^-2 Hz^-1), lower plot: magnetic (nT^2 Hz^-1) ) as a function of operating frequency (in a logarithmic scale on vertical axis) and time (horizontal axis). At the top of each plot is a title indicating the Instrument, Receiver and Antenna used along with the time span for the spectrogram. Overlaid on each image is a trace of the electron gyrofrequency. Beneath the time labels on the horizontal axis of the lower plot are ephemeris data: position of the spacecraft in radial distance (Earth radii), geomagnetic latitude, magnetic local time, and McIlwain L-shell. Overlaid on each image is a trace of the electron gyrofrequency. Reference: Gurnett, D.A. et al, The Polar plasma wave instrument, Space Science Reviews, Vol. 71, pp. 597-622, 1995.