Equatorial Plasma Instabilities and Mesospheric Turbulence - The Earth's Ionosphere: Plasma Physics and Electrodynamics - page 180

Jicamarca
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Relative echo power (dB)

Figure 4.24 Sample of the 50MHz backscattering power profiles from the electrojet
irregularities measured with the large vertically directed incoherent scatter antenna at
Jicamarca. Spread F echoes contaminated the data between 0405 and 0550 and perhaps at
1900. [After Fejer et al. (1975). Reproduced with permission of the American Geophysical
Union.]

We turn now to complementary data sets obtained from sounding rockets
flown through the daytime and nighttime electrojets. Most of the early rocket
experiments (prior to 1983) were flown with relatively high apogees and thus
passed through the electrojet very quickly. Such high velocities preclude detec-
tion of the large-scale waves discussed previously. Nonetheless, some impor-
tant results were obtained, particularly due to the pioneering efforts of the
Indian rocket group (e.g., Prakash et al., 1972). Examples of simultaneous den-
sity profiles and density fluctuation measurements taken during daytime and
nighttime conditions are shown in Fig. 4.26. During the day, the fluctuations
in electron density were located where the gradient is upward, were peaked
at 103 km, and were relatively unstructured. The nighttime zero-order den-
sity profile is very structured on the negative gradient at about 120 km, with