Internal waves their characteristics dynamics and application with special emphasis on Indian waters

Abstract

Internal waves (IWs) are the waves in the pycnocline (regions of rapid changes newlinein density). Studies of IWs continues to be an active area of research due to its newlinenumerous applications, viz. upper ocean dynamics, ocean energy budget, biological newlineactivity, underwater sound propagation, etc. This thesis entitled Internal Waves: newlineTheir characteristics, dynamics and application with special emphasis on Indian newlinewaters , documented and explained the salient features of shallow and deep water newlinecharacteristics of IWs surrounding India. A detailed literature survey of IW studies newlinewith special emphasis on the Indian waters is presented. The backbone of the thesis is newlinethe time series of hydrographic profiles (gt 1 lakh) collected from the shallow and deep newlinewaters covering different months (vertical mooring and onboard vessels). newlineThe characteristics of low and high frequency IWs were described at selected newlinelocations in the north-eastern Arabian Sea, central- eastern Arabian Sea, south-eastern newlineArabian Sea, north-western Bay of Bengal, Andaman Sea and east central Arabian newlineSea. The Fast Fourier Technique and Wavelet Techniques were utilized to resolve the newlinedominant harmonics of IWs in the time series data and their temporal evolution. The newlineanalysis revealed the dominance of IWs with tidal periodicity at all the locations with newlinelarge spatio-temporal variations. The amplitude and the frequency bands of IWs were newlinefound depend on the degree of vertical stratification in the thermocline region. The newlinehigh frequency IW was found riding over low frequency internal tides and contained newlinemaximum activity at its crest. newlineThe widely Garret-Munk spectrum that gives a statistical representation of IW newlinefield in terms of energy spectrum and vertical displacement with respect to time and newlinespatial scales was implemented. To simulate the diurnal variation in the temperature newlineand salinity field, the 1-D profile model of Price, Wellor and Pinkel was utilized newline(1986).