Jicamarca Faraday Experiments

These data are derived from the Faraday rotation experiment, one of the primary modes of operation of the Jicamarca Radio Observatory. Jicamarca (11.9 deg S, 76 deg W) is a 50 MHz incoherent scatter radar that has been in continuous operation since the early 1960s. The Faraday experiment was performed early in the history of the observatory but was discontinued until the mid 1980s, when the computers of the time became sufficiently powerful to tabulate the necessary lag products in real time. It was found that the quality of the experiment could be improved considerably by accounting for and subtracting experimental biases introduced by polarization crosstalk, imperfect quadrature detection, and other subtle effects. These corrections are now routinely made to the data. In the mid 1990s, numerous flaws in the Jicamarca antenna array caused by corrosion were repaired, and the quality of the Faraday data improved still further.

Two variations on the basis Faraday double pulse experiment are available at Jicamarca. One of these, mode 1801, combines long alternating coded pulses with the standard double pulses to extend the altitude range of the experiment into the topside. The pulse transmission rate for this experiment is half that of the stadard double pulse, implying a degredation of data quality below 450 km altitude. The other experiment, mode 1802, combines a long uncoded pulse with the double pulse. This mode extends the altitude range of the experiment further but still compromises the data quality below 450 km.

The power profiles, computed from double pulse data at all altitudes in the standard double pulse mode, are calibrated to the Faraday rotation data but are not corrected for unequal electron and ion temperatures. This is because the data sometimes represent coherent echoes from plasma irregularities, for which such a correction makes no physical sense. Users are free to make the correction themselves in portions of the data uncontaminated by coherent echoes.

This is an interactive website which processes data and generates graphical output on the fly. Electron density, temperature, and H+ concentration can be viewed in either power map format or as time- or height-averaged line plots. The size of the window for plotting and averaging can be specified below. More data will appear as they become available. These images should be regarded as "first look" in nature.