Miscellaneous information 1989 (Addendum)

Miscellaneous information 1989 (Addendum)     

Alkaline rocks of the deccan traps

Recent investigations on the Deccan Traps reveal many new findings of alkaline rocks more commonly occurring as minor intrusions than as lava flows. In comparison to the vast extent of the Deccan Traps, the alkaline rocks are negligible in their volume and are confined to tectonic belts in parts of Western India. The rocks exhibit no systematic variation in their petrographical and chemical characters thereby suggesting that they were not derived from a primary alkali olivine-basalt magma. The possibility of derivation of alkaline magma locally along the rift zones is proposed. Some of the alkaline rocks are shown to have been formed due to the effective role of volatiles in bringing dissociation of feldspar in certain cases, and alkali metasomatism in others. The syntexis of the pre-Deccan Trap carbonate rocks along the Narmada rift zone is also responsible for some occurrences.     

A computer program for interpreting vertical magnetic anomalies of spheres and horizontal cylinders

Summary A common computer program for the interpretation of vertical magnetic anomalies of spheres and horizontal cylinders has been developed. The input consists of the observed anomalies noted against their distances measured from an arbitrary point in the profile and a code number for each model. The program is written so that the positions and magnitudes of the maximum and minimum anomalies are located and their ratios and signs are used to define the initial parameters of the model under consideration. The errors resulting from these approximate values are derived and are solved for the increments to be given to the initial values. The process is repeated until the sum of the squares of the errors is less than 0.25% of the sum of the squares of the observed anomalies. The method has been tested on various theoretical examples and the results justify the validity of the programme.     

Ozone and airglow in the mesosphere region

The paper presents the results of a photometric study of the hydroxyl bands (7–2) and (8–3) in the night airglow spectrum at Mt. Abu in the winter and spring of 1966–1972. The observed nocturnal variation differs from the variation expected from the theoretical studies of Hesstvedt, Hunt, Shimazaki and others. Instead of a gradual fall in intensity after sunset to shortly before sunrise, a peak in intensity is found at a time which changes from month to month and roughly coincides with the transit times of the X-ray star TAU (XR-1)-Crab Nebula. Anexplanation of the observed phenomenon is offered in terms of the increased energy output into the D and E regions of the atmospheres, increased eddy diffusion, and production, of additional O(³P) and O₃ in the region 80–95 km. O₃ reacting with H gives rise to OH^*.     

Incoherent cerenkov radiation and its amplification via the landau instability

Quite often the VLF hiss powers recorded by space probes are some orders of magnitude greater than those predicted by the theory of incoherent Cerenkov radiation. In this note we suggest that the wavegrowth via the Landau instability might satisfactorily account for the disparity between the theory and experiment.     

Rare gases on the Earth and in meteorites

Analysis of abundance patterns of rare gases Ne²², Ar³⁶, Kr⁸⁴ and Xe¹³⁰ on Earth and in ordinary and carbonaceous chondrites is presented. A mechanism of chemical adsorption of rare gases at the planetesimal stage during their accretion is proposed to generate the abundance pattern of the heavy rare gases on the Earth. The calculated values for Xe and Kr agree well with the observed values whereas for Ar, the agreement is poor.     

Diffuse X-ray background measurements in the energy range 2–18 keV

Rocket measurements, of the diffuse X-ray background in the energy range 2–18 keV, conducted from Thumba Equatorial Rocket Launching Station (TERLS), India, are presented. The estimates of the cosmic background are derived by the method which employs the Earth and its atmosphere as a shutter to intercept the celestial X-rays. The results are shown to be consistent with a power law photon spectrum.13.6 _–3.3 ^+4.3 E ^{–1.73±0.15} photons/cm²-sec-keV-ster the spectrum being much flatter than that observed at higher energies.     

Salt and pepper cleaning on the landsat processed images

This paper proposes an algorithm for removing the unwanted pixels from the categorized Landsat data without disturbing the features in the categorized data. Sample outputs of the smoothed data and unsmoothed data (original data) are presented.     

Correlation of water quality parameters and products of exotech radiometer bands

In the analysis of water quality by remote sensing, it is widely reported, that, several parameters of water quality are correlated with the reflectances and the ratios of reflectances of the water body in different spectral bands. In this paper, it is shown empirically, that, the pairwise product of the reflectances in different bands is better correlated than the bands and their ratios. A possible explanation for this pnenomenon is also suggested.