NOPR Collection:

Ionospheric Radiowave Absorption by Al-Technique-A Test for the IRI Model

Mon, 01 Aug 1988 00:00:00 GMT

Title: Ionospheric Radiowave Absorption by Al-Technique-A Test for the IRI Model Authors: Pramod, D; Nath, Narinder; Setty, C S G K Abstract: Ionospheric absorption of 2.132 MHz radiowave measured by AI-technique at Delhi is compared with the absorption calculated by using the IRI model N(h) and standard v(h) distributions applicable to the lower absorbing ionospheric region. It is found that the calculated absorption is too high whereas the calculated heights of reflection are too low compared to the observed values. Page(s): 144-146

Intensity of Low Latitude ELF Emissions

Mon, 01 Aug 1988 00:00:00 GMT

Title: Intensity of Low Latitude ELF Emissions Authors: Prakash, Ram; Singh, Birbal; Jain, V K Abstract: Using a realistic ionospheric model and suitable plasma parameters, magnetic field intensities have been calculated for low latitude ELF emissions observed both on the ground and aboard satellite. A close agreement between the calculated and the observed intensities confirms the earlier suggestion of Prakash and Singh [Indian J Radio & Space Phys, 12 (1983) 156] that the low latitude ELF emissions are generated in cyclotron resonance instability mechanism. Page(s): 140-143

Excitation of Electrostatic Cyclotron Harmonic Waves in Magnetosphere

Mon, 01 Aug 1988 00:00:00 GMT

Title: Excitation of Electrostatic Cyclotron Harmonic Waves in Magnetosphere Authors: Gwal, A K; Singh, Manjesh Abstract: Wave-particle interaction in the magnetosphere has been studied for wave frequencies at the cyclotron harmonics of electrons and ions. A generalized dispersion relation for electrostatic wave, propagating nearly perpendicular to the magnetic field in non-Maxwellian plasma has been considered. Expressions of damping and growth rate for electrostatic electron and ion cyclotron harmonic (ICH) waves have been derived and computed results have been demonstrated for the magnetospheric plasma parameters. The growth of electron cyclotron harmonic waves may be interpreted in terms of the observed electron cyclotron harmonic emissions due to energetic electrons and ICH waves by energetic ions in the magnetospheric plasma. The damping of the waves may explain the heating of the magnetospheric plasma. Page(s): 135-139

Optical Extinction Coefficient of Fogs

Mon, 01 Aug 1988 00:00:00 GMT

Title: Optical Extinction Coefficient of Fogs Authors: Leelavathi, H; Channappa, K H Abstract: The optical extinction coefficient of some selected fog models are calculated using an approximate method. The approximation consists in using an average value of the extinction efficiency, the averaging being performed over a limited range of the radii of scatterers including the drop size of largest frequency. The values thus calculated are compared with the values calculated using the extinction efficiency averaged over the complete drop-size distribution describing the fog, and are found to be in close agreement for all the values of critical size parameter greater than 20. Page(s): 132-134