http://nopr.niscpr.res.in/handle/123456789/38378 Thu, 08 Oct 2026 17:20:24 GMT 2026-10-08T17:20:24Z http://nopr.niscpr.res.in/handle/123456789/38553 Title: Phase Spectral Composition of Wind Generated Ocean Surface Waves Authors: Varkey, M J Abstract: A study of the composition of the phase spectra of wind generated ocean surface waves is carried out using wave records collected employing a ship borne wave recorder. It is found that the raw phase spectral estimates could be fitted by the Uniform probability distribution in all cases with widely varying confidence levels. Gaussian fits are found suitable with varying confidence levels for smoothed phase spectra for narrow and wide band variance spectra except when the spectra are well differentiated into 2 wave systems with a dominating local sea. For this type of sea states, a directional tuning in the directional phase spectra could be expected. A new spectra width parameter which is equally applicable to spectra of narrow band, wide band and multipeaked nature is also defined. Page(s): 181-188 Thu, 01 Sep 1988 00:00:00 GMT http://nopr.niscpr.res.in/handle/123456789/38553 1988-09-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/38552 Title: Effect of Phase Coupling on Surface Amplitude Distribution of Wind Waves Authors: Varkey, M J Abstract: Nonlinear features of wind generated surface waves are considered here to be caused by nonrandomness (non-Uniform) in the phase spectrum. Nonrandomness in recorded waves, if present, would be generally obscured within the error level of observations and computations. Hence some numerical experiments are tried by inserting known nonrandomness in the phase spectrum to study the nonlinear effects. The results show significant changes in the surface amplitude distributions. The possible occurrence of nonrandomness in phase spectrum in natural situations is discussed. Page(s): 189-194 Thu, 01 Sep 1988 00:00:00 GMT http://nopr.niscpr.res.in/handle/123456789/38552 1988-09-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/38551 Title: Distribution and Behaviour of Fluoride in Mandovi and Zuari Estuaries, Central West Coast of India Authors: Sousa, S N De; Gupta, R Sen Abstract: Fluoride concentrations in Mandovi and Zuari estuaries are regulated largely by salt water intrusion. Highest concentrations are observed during the premonsoon season, when the salt water intrusion is also the highest, the concentration increasing from fresh water-end to the sea-end. During monsoon, however, fluoride concentrations are the lowest and the estuaries show freshwater characteristics at the surface while at the bottom higher fluoride concentrations are observed near the mouth as a result of salt wedge formation. Postmonsoon season shows a recovery period when the fluoride concentration has values lying between those during premonsoon and monsoon. F-Cl relationship is linear during monsoon and postmonsoon indicating that fluoride behaves conservatively during these 2 seasons. During the premonsoon, however, the F-Cl relationship is not linear but exponential of the type Y = abx which is curve concave to the fluoride-axis indicating that fluoride is lost in estuaries in this season (28 and 25U+0025 in Mandovi and Zuari respectively). Page(s): 195-201 Thu, 01 Sep 1988 00:00:00 GMT http://nopr.niscpr.res.in/handle/123456789/38551 1988-09-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/38550 Title: Nature, Distribution and Origin of Clay Minerals in Grain Size Fractions of Sediments from Manganese Nodule Field, Central Indian Ocean Basin Authors: Rao, V Purnachandra; Nath, B Nagender Abstract: DT, IR and X-ray diffraction analyses have been carried out on 3 grain size fractions (1, 1-2 and 2-4 mu m) of sediments from the Central Indian Ocean Basin. Results indicate that there are 2 smectite minerals (montmorillonite and Fe-rich montmorillonite). Montmorillonite is present in all size fractions of sediments, whereas Fe-rich montmorillonite is present only in 1 and 1-2 mu m fractions of siliceous and 1 mu m fractions of pelagic clays. Distribution of clay minerals suggests that illite, chlorite and kaolinite are the detrital products from Ganges and Brahmaputra and montmorillonite is derived from the weathering of the ridge rocks-Fe-rich montmorillonite in siliceous and pelagic clay is a result of early diagenetic processes. Size fraction studies suggest that montmorillonite tends to crystallise in 2 mu m size range. Page(s): 202-207 Thu, 01 Sep 1988 00:00:00 GMT http://nopr.niscpr.res.in/handle/123456789/38550 1988-09-01T00:00:00Z