Vertical distribution of temperature, salinity and Dissolved oxygen in the Maldives region of The Indian ocean

The hydrographical features existing in the region from I ' S to 8° N between the meridians of 71° E and 80° E during September—October 1962 are presented and discussed. A well - developed thermocline is observed in the investigational area and an upslope towards north is noticed in the eastern regions. Below 500 m depth the distribution of temperature in all the sections are similar. A salinity maximum is observed in the northern part of all the sections at the top of the thermocline and towards the equator this maximum is not at all conspicuous, and the water masses have more or less uniform salinity throughout the vertical. Dissolved oxygen distribution in the vertical showed good comparison to the observations already made in the Laccadive region. Occurrence of oxygen deficit layer between 30J and 1250 m is observed with increase in oxygen content from 1250 m downwards, and values as high as 3.5 ml/1 were observed at 3000 m depth

Fishery Oceanography

The ocean in itself is not a homogenous medium although it is a single phase environment. The temperature, the amount of dissolved organic and inorganic matter, the amount of dissolved gases and the physical nature of the ocean are subject to various changes seasonally and regionally. The climatic conditions of the atmosphere also affect the ocean and the exchange of energy between (he sea and the atmosphere is also important in this respect. The in situ changes in the of an affect the production of planktonic organisms which form the food material for the fish. The spatial differences in the mass distribution of the oceans which can be estimated from temperature and salinity, give rise to ocean currents, which help the transport of fish eggs and larvae and which affect the movements of adult fish also. Thus the fluctuations in the environmental conditions have a profound influence on the aperiodic and seasonal migrations and occurrence of fish. Furthermore, the conditions in the aquatic environment and their changes influence the recruitment, survival and growth of fis

Estuarine oceanography of the Vembanad lake Part II : the region between Cochin and Azhikode

Some aspects of the estuarine oceanography of the Vembanad lake between Cochin and Azhikode are discussed. Since this part of the lake is in confluence with the Arabian sea at its southern and northern ends, at Cochin and Azhikode, its circulation pattern and other characteristics are different from what they are between Cochin and Vaikom. Because of the position of these two mouths, which are exposed to the same tidal cycles, the high tides and low tides each producing two opposite flows respectively converge and diverge leaving a null zone, almost free of the tidal effect, around Kadakara, situated midway between Cochin and Azhikode. Another significant feature of this pairt of the estuary is an extreme low-salinity i«gion between Karthedam and Cherai during monsoon and early postmonsoon, brought about by the deflected waiters of the Periyar, opening at the northern end of the estuary

Design of Routers for Optical Burst Switched Networks

Optical Burst Switching (OBS) is an experimental network technology that enables the construction of very high capacity routers using optical data paths and electronic control. In this dissertation, we study the design of network components that are needed to build an OBS network. Specifically, we study the design of the switches that form the optical data path through the network. An OBS network that switches data across wavelength channels requires wave-length converting switches to construct an OBS router. We study one particular design of wavelength converting switches that uses tunable lasers and wavelength grating routers. This design is interesting because wavelength grating routers are passive devices and are much less complex and hence less expensive than optical crossbars. We show how the routing problem for these switches can be formulated as a combinatorial puzzle or game, in which the design of the game board determines key performance characteristics of the switch. In this disertation, we use this formu-lation to facilitate the design of switches and associated routing strategies with good performance. We then introduce time sliced optical burst switching (TSOBS), a variant of OBS that switches data in the time domain rather that the wavelength domain. This eliminates the need for wavelength converters, the largest single cost component of systems that switch in the wavelength domain. We study the performance of TSOBS networks and discuss various design issues. One of the main components that is needed to build a TSOBS router is an optical time slot interchanger (OTSI). We explore various design options for OTSIs. Finally, we discuss the issues involved in the design of network interfaces that transmit the data from hosts that use legacy protocols into a TSOBS network. Ag-gregation and load balancing are the main issues that determine the performance of a TSOBS network and we develop and evaluate methods for both

Oceanographic features and abundance of the pelagic fisheries along the west coast of India

The results of a study on the hydrographic properties such as temperature, salinity and Sigma-T (density) content of the surface waters along the west coast of India collected during the cruises of R. V. Varum and other vessels are presented e,s an average distrbution of the factors month-wise for each degree square. This has been used to investigate the relationship of the hydrographic conditions with the pelagic fishery landings such as thpsp of the oil sardine and the Indian mackerel month-wise. The importance of the coastal phenomena like upwelling and sinking in relation to the fishery landings is pointed out

Programming Active Networks Using Active Pipes

Active networks allow customized processing of data traffic within the network which can be used by applications to improve the quality of their sessions. To simplify development of active applications in a heterogeneous environment, we propose active network pipes as a programming abstraction to specify transmission and processing requirements. We describe a routing algorithm that maps application session requirements onto network resources and determines an optimal route through the network transiting all required processing sites. Additionally, we propose a network software architecture to implement the functionality required to support active pipes

On circulation of Indian Ocean waters east of Maldives During the post monsoon period

The circulation patterns in the Maldive region between the 71° and 80°E meridians within the equator and 8°N are discussed. It is observed that a large cyclonic gyre exists in the northern regions and an anticyclonic one in the southern region, mainly in the subsurface layers. These are supposed to be associated with divergence and convergence phenomena occurring in the area. The influence of the Maldive islands and the associated bottom topography in the formation of these circulation patterns is indicated

Studies on the biology of Nematopalaemon tenuipes (Henderson) in Bombay coast

The relationship between total and carapace length of Neinatopalaemon 'tenuipes, is calculated as L = -0.82 + 4.595 C, where L and C are total and carapace lengths in mm respectively. Juveniles of less than 33 mm grow at the rate of 6.43 mm per month, whereas the adult female and male grow at the rate of 3.74 and 2.81 mm per month respectively. The fishery is almost entirely composed of 0-year class. Life span of the species appears to be about eighteen months. Existence of sexual segregation has often been noticed. The minimum size at which the female prawn breeds is found to be 50 to 52 mm, when it is about eight months old. Maturation of the ovary and incubation of the eggs to the hatching stage are likely to be accomplished within about a month. About 5 to 6 percent of the total breeding females produce second brood in the same season. The species breeds throughout the year, with the peak season from July to October. A bopyrid parasite infests about one perce.nt of the total population

On the relative (Geostrophic) currents in the south eastern Arabian Sea

Determination of space distribution of ocean currents in the sea is one of the most important problems in dynamical oceanography. Such studies facilitate the determination of the areas of convergence and divergence in the ocean, which are of important consequence to the fertility and thus to the fisheries of the region (Hela and Laevastu, 1961). Studies regarding current patterns along the west coast of India from hydrographical observations have been made by the Central Marine Fisheries Research Institute, from the data collected on board the research vessels VARUNA and, KALAVA (Sastry, 1959 ; Ramamirtham etal, 1960 ; Jayaramane/ al.,1960 ; Patil et al., 1963). The above-mentioned accounts pertained to a coastal belt of maximum width 150 miles only, and for localised areas around the Laccadives. Moreover, in all these studies the main properties considered for the current studies were temperature and Sigma-T only, as the data collected were not sufficient to permit a detailed study using the method of dynamic computation. During the period November 1962 - January 1963 detailed hydrographic studies were made in the southeastern Arabian Sea, covering a vast region between 11° and 17° N, within the meridians of 70° and 75° E. The observations were extended to deeper waters of 2000-3000 m., and the whole region was covered within a period of nearly one and a half months. Hence it was considered worthwhile to attempt a detailed study of the current patterns from the geopotential topographies of the isobaric surfaces, and the data collected were quite sufficient for the purpose

Carbondioxide equilibria and nutrient availability in two culture ponds at Narakkal during three monsoon and postmonsoon months, June - September, 1984

The nutrient availability did not show a definite pattern and not much correlation was observed between the biological cycle of nutrients and carbondioxide content. The variations of the different hydrological parameters of the ponds as well as their diurnal variations are discussed