Mixed layer characteristics and hydrography off the west and east coasts of India

In this thesis, a detailed attempt has been made to understand the general hydrography of the upper 300m of the water column, in the eastern Arabian Sea and the western Bay of Bengal, the two contrasting basins in the northern Indian Ocean, using recently collected data sets of Marine Research-Living Resources (MR-LR) assessment programme, funded by Department of Ocean Development, from various cruises, pertaining to different seasons. Initially it discuss the general hydrography of the west and east coasts of India are covered, in the context of mixed layer processes. The study describes the materials and methods . To compare the hydrography of the AS and BOB, a unique MLD(Mixed Layer Depth) definition for AS and BOB is essential, for which the 275 CTD profiles were used. A comparison has been made among the various MLD criteria with the actual MLD. The monthly evolution of MLD, barrier layer thickness and the role of atmospheric forcing on the dynamics of the mixed layer in the AS and BOB were studied. The general hydrography along the west coast of India is described. The upwelling/downwelling, winter cooling processes, in the context of chemical and biological parameters, are also addressed. Finally the general hydrography of the Bay of Bengal is covered. The most striking feature in the hydrography are the signature of an anticyclonic subtropical gyre during spring intermonsoon and a cold core eddy during winter monsoon. The TTS(Typical Tropical Structure) of the euphotic layer was also investigated.

Ecobiogeography, Spatial and Temporal Variations of Microzooplankton Along the East Coast of India

In the present study an attempt has been made to understand the microzooplankton community along the easr coast of India. Most of the earlier studies projected Bay of Bengal as an oligotrophic system where phytoplankton growth is limited by a number of factors among which nutrients are the foremost. Hence it is logical to consider that the most of the primary production in the Bay of Bengal could be contributed by small sized phytoplankton harnessing the available resources, which in turn can be utilized effiency by the microzooplankton only. Hence microzooplankton could play in transferring primary organic carbon to higher tropic levels in this region.

Studies on storm surges and sea level variations along the east coast of india

It became so usual for the east coast of India to face at least IO to 15 cyclones every year, out of which 3 to 4 may reach the deep depression stage. As a result the east coast of India experiences frequent heavy damages of varying intensities due to storm surges and it is also not unusual to experience a calamitous deluge once in a decade or so. Loss of life and damages can be minimized only if the magnitude of the surge could be predicted at least a day in advance. Therefore, an attempt to study the storm surges generated by the cyclones that strike the east coast of India and. suggest a method of predicting them through nomogram is made

Echno economic studies on industrial fishing in the upper east coast of India

The present scenario of industrial fishing in India is that most of large trawlers are based at Visakhapatnam and congregate in the potential shrimp ground in the upper East coast of India commonly known as the Sandheads. These are outriggcr vessels operating two or four trawl nets along with a testing trawl called try net. In the early Seventies these vessels were operating on a very high economic return which was evident from the steady increase in number of outriggers over a period of twenty years. Since the total allowable catch has to be shared by all vessels including the increasing fleet, reduction per vessel output is bound to happen. Therefore some of them could not survive the competition and withdrew from the scene. The number of outriggers did not increase subsequently. However, there arose a doubt whether the existing fleet of about 180 vessels are fishing economically or whether there is any scope for further introduction of industrial vessels in the region. This study is focussing to the techno economic aspects of industrial fishing in the upper East coast of India

Population Biology And Ecology Of Artemia From Salinas Of South East Coast Of India

This thesis deals with the population characteristics of Artemia and the effect of different environmental parameters on the different stages of Artemia in a salina at Tuticorin, south east coast of India. The present investigation was carried out from 1985 to I987. The study was initiated by undertaking a survey to find out suitable Artemia habitats along the south east coast of India and a perennial salina with an area of 0.25 ha was selected at Karapad (Tuticorin). Weekly samplings were made for two full calender years (1986-87) to collect the different stages of Artemia population as well as the different environmental parameters. The thesis comprises of the following sections: Introduction, materials and methods, systematics, biology and distribution of Artemia, results and discussion, summary and bibliography. The section on results and discussion gives the characteristics of Artemia population in the salina, the seasonal variations of different environmental parameters in the salina and their effects on different stages of Artemia population. Description of an experiment conducted to show the sudden changes of salinity on different stages of Artemia is also given as a separate section.

Computational models for the prediction of severe thunderstorms over east indian region

Thunderstorm is one of the most spectacular weather phenomena in the atmosphere. Many parts over the Indian region experience thunderstorms at higher frequency during pre-monsoon months (March- May), when the atmosphere is highly unstable because of high temperatures prevailing at lower levels. Most dominant feature of the weather during the pre-monsoon season over the eastern Indo-Gangetic plain and northeast India is the outburst of severe local convective storms, commonly known as ‘Nor’wester’ or ‘Kalbaishakhi’. The severe thunderstorms associated with thunder, squall line, lightning and hail cause extensive losses in agriculture, damage to structure and also loss of life. The casualty due to lightning associated with thunderstorms in this region is the highest in the world. The highest numbers of aviation hazards are reported during occurrence of these thunderstorms. In India, 72% of tornadoes are associated with this thunderstorm.

Numerical Modelling of Tsunami Propagation in the South East Arabian Sea (SEAS) and Inundation along the Kerala Coast

Tsunamis are water waves generated by a sudden vertical displacement of the water surface. They are waves generated in the ocean by the disturbance associated with seismic activity, under sea volcanic eruptions, submarine landslides, nuclear explosion or meteorite impacts with the ocean. These waves are generated in the ocean and travel into coastal bays, gulfs, estuaries and rivers. These waves travel as gravity waves with a velocity dependent on water depth. The term tsunami is Japanese and means harbour (tsu) and wave (nami). It has been named so because such waves often develop resonant phenomena in harbours after offshore earthquakes.

Rainfall Climatology over Middle East Region and its Variability

A better understanding of the rainfall climatology of the Middle East region identifying the mechanisms responsible for the rain producing systems is essential for effective utilization of the water resources over the arid region. A comprehensive analysis on the rainfall climatology of the Middle East region is carried out to bring out the spatial and temporal variation of rainfall and mechanisms responsible for the rain events. The study was carried out utilizing rainfall, OLR, wind and humidity data sets procured from TRMM, NOAA and NCEP-NCAR. Climatology of annual rainfall brings out two areas of alarmingly low rainfall in the Middle East region: one in Egypt, Jordan and adjoining areas and the other in the southern part of Saudi Arabia. Daily rainfall analysis indicates that northern region gets rainfall mainly during winter and spring associated with the passage of Mediterranean low pressure systems whereas rain over the southern region is caused mainly by the monsoon organized convection, cross equatorial flow and remnants of low pressure systems associated with the monsoon during the summer season. Thermodynamic structure of the atmosphere reveals that the region does not have frequent local convection due to insufficient moisture content. The sinking motion associated with the sub tropic high pressure system and subsidence associated with the Walker circulation are responsible for maintaining warm and dry air over the region.