Inference of equatorial field-line-integrated electron density values using whistlers

The nighttime electron density integrated along a magnetic field line at very small L-values (about 1.06) is inferred by comparing whistler dispersions, measured from a sounding rocket, with model ionospheric calculations. At a local time of 0500 LT, the electron density in the F-layer valley was found to be about 1000 per cu cm. It is suggested that this technique can be applied to earlier times in the local evening to determine ionospheric conditions which benefit the growth of low-latitude plasma instabilities.