Decameter and meter wavelength radar studies of artificial plasma clouds in the lower ionosphere, 2. Unstable evolution in the lowerElayer and some implications, regarding sporadicE

摘要: Radio frequency scattering experiments have indicated that irregular fluid motions of tens meters spatial scale and tenths seconds temporal occur in the E region. It has been suggested there can also this region a dissipative plasma instability (similar to what termed gradient-drift or E×B previous work) displays these scales may be importance evolution sporadic E. This paper describes an attempt study circumstances under which such might appear by injecting alkali clouds into lower observing them with decameter meter wavelength, coherent-pulse-Doppler radar. After initial blast-wave-driven expansion phase, cloud undergoes period behavior, number discrete echoes from seemingly coherent, large, short-lived reflectors superimposed on generally diffuse radar echo. Their large apparent size spectral discreteness indicate they arise ordered, possibly wavelike structure, must involve entire cloud. Comparison observed growth rates probable instabilities order-of-magnitude calculations quantities based linear analysis confirms postulated indeed explain behavior. In one phase reflecting layer similar is formed, permits wavelength radiation, incident obliquely cloud, reflected back earth much same manner as sky-wave transmission achieved via The similarity behavior artificial patch natural variety evident. Also, nonlinear, two-dimensional capable explaining appearance variation data An association between results mechanism temperate latitude formed.