Rozprawy doktorskie na temat „Ocean - North India”

The first observations of deep-demersal scavenging fishes are presented from three regions of the world’s oceans with contrasting overlying productivity: the Mid-Atlantic Ridge (MAR) and Nazaré Canyon, Northeast Atlantic Ocean, and the Crozet Plateau, Southern Indian Ocean.  The MAR is the most significant topographic feature of the North Atlantic Ocean and is under the influence of a sub-polar front with increased productivity to the north.  Twenty-two taxa were photographed at bait; 14 at 42°N and 17 over two transects at 51 and 53°N respectively.  Decreases in biodiversity across the 51°N transect compared to the 42 and 53°N transects, support the hypothesis that 48°N - 52°N is a region of faunal change in demersal fish assemblages in the North Atlantic Ocean. The Nazaré Canyon is a large submarine canyon intersecting the Iberian continental margin which received high levels of organic matter from local upwelling and terrigenous sources. Nine fish species were photographed at the baited ROBIO lander at all depths within the canyon. It is hypothesised that the increased organic input positively influences benthic food supply within the canyon, supporting elevated populations of scavenging fauna.  The Crozet Plateau is situated in the southern reaches of the Indian Ocean, where the abyssal seafloor (ca. 4200 m) received differing levels of surface-derived organic enrichment.  Demersal ichthyofaunal biodiversity, abundance and biomass were sampled by a trawl at a eutrophic site (M5) and oligotrophic site (M6). Demersal fish species richness, abundance and biomass were greater at M5 compared to M6, and dominated by Macrouridae.  However, overall results were not significant, leading to the conclusion that the rattail fishes are transient between sites. Six species new to science were collected and are described herein (one Ophidiid, three Liparidae and two Zoarcidae), as well as several other rare specimens of Ophidiid and Zoarcid.

The applications of mid-Cretaceous (Aptian-Cenomanian) nannofossils in biostratigraphy and palaeoceanography have been advanced based on four specific studies from India, UK, the Atlantic and Pacific Oceans. A biostratigraphic study on outcrop samples from two new sections in the Cauvery Basin (SE India) has significantly improved stratigraphic resolution in the basin using the recent zonation schemes of Bown et al. (1998) and Burnett (1998). In addition to highlighting problems associated with a few marker species for the Cenomanian, the Albian/Cenomanian and Cenomanian/Turonian boundaries have been examined with respect to their nannofossil proxies. Qualitative comparisons of coeval assemblages from India with those from three other palaeogeographical settings (England, France and the Pacific) have confirmed the overall cosmopolitan nature of Albian nannofloras, in which provinces such as the Tethyan, Boreal and Austral cannot be clearly differentiated. A palaeoclimatic study of a short section in the Gault Clay (S. England) suggests a major warming event starting at the mid-/Late Albian boundary in the Weald of the Anglo-Paris Basin. The cold-water species, Repagulum parvidentatum, gives strong evidence for this warming event by showing a rapid decline in its percentage abundance, which precisely coincides with a light oxygen isotope peak and the influx of Tethyan ammonites. A sharp productivity rise based on the well-known fertility index, Zeugrhabdotus noeliae, is found to be concomitant with the warming event. A palaeoceanographic study of the Early Albian OAElb event in the western North Atlantic (Leg 171B), based on its nannofossil productivity record and geochemical data, supports the increased productivity model as a plausible mechanism for this anoxic event. A similar study on the Pacific Ocean (Leg 198, Shatsky Rise) shows a marked temporal variation in the abundance distribution of productivity- related taxa (e.g., Biscutum constans, Zeugrhabdotus noeliae) in relation to the OAEla (Early Aptian) and OAElb (Early Albian) events. Possible explanations for this variation have been proposed, in light of the heightened submarine volcanism in the Pacific during the mid-Cretaceous. Watznaueria is found to be the most abundant taxon in all mid-Cretaceous assemblages and its dominance is considered to be independent of preservation, indicating its broad palaeoecological tolerance rather than resistance to dissolution. On the basis of taxonomic observations, four new species have been erected: Calculites karaiensis, Loxolithus bicyclus, Manivitella fibrosa and Tranolithus simplex.

The north Indian Ocean is one of the highly productive regions among the tropical oceans. Being a prominent monsoon regime, the basin exists as a highly dynamic region charac- terised by intense mixing and upwelling and strong surface currents. This provides a favourable background for the formation of strong surface chlorophyll blooms through ef- cient vertical supply of biologically rich subsurface waters. Earlier studies have suggested the determinant role of upper-ocean physical processes associated with the monsoons in controlling the biological productivity of the north Indian Ocean. A strong seasonality is observed in the surface chlorophyll distribution of the north Indian Ocean, with two blooming seasons, the summer and winter monsoons, in which the former is the most productive season. The seasonally reversing monsoon winds favour vertical mixing and upwelling, whereas the surface freshwater in flux, mainly through the monsoonal river dis- charge, weakens the vertical processes by increasing density strati fication. The competing impacts of the monsoonal wind and freshwater forcings on the density structure of the upper ocean determine the vertical transport of nutrients and chlorophyll from the subsur- face layers to the surface sunlit layers. Additionally, the seasonality in surface chlorophyll is often regulated by the basin-wide variability in surface wind patterns associated with interannual events, like the Indian Ocean Dipole (IOD) and the El Nino. Despite being a highly productive basin with complex dynamical characteristics, the north Indian Ocean remains undersampled, unlike the other tropical oceans. Extensive research efforts are needed incorporating both observations and biogeochemical modelling, in order to ll the gaps in our understanding of the phytoplankton dynamics of the basin. This thesis investigates the role of upper-ocean physical processes, acting at seasonal and interannual timescales, in controlling the chlorophyll distribution of the north Indian Ocean, focusing on some of its biological hotspots that develop during summer. The selected study regions are the major upwelling zones around the Indian subcontinent, the northwestern BoB (NWBoB), the southern BoB (SBoB), and the southeastern Ara- bian Sea (SEAS), which contribute signi cantly to the marine sheries production of the country. In particular, the study focuses on the relative importance of surface wind and freshwater forcings in determining the formation and evolution of the surface chlorophyll blooms. Special attention is given in documenting the vertical distribution of chlorophyll, especially the deep chlorophyll maxima (DCM). The study makes use of a wide range of datasets, including satellite observations, in situ measurements from Seagliders deployed during the Bay of Bengal Boundary Layer Experiment (BoBBLE) eld program, and sim- ulations from a coupled physical-biogeochemical model. The Seagliders provide vertical pro les of chlorophyll at high-resolution, which is suitable to study the DCM with large spatio-temporal variability. The biogeochemical model, the Tracers of Phytoplankton with Allometric Zooplankton (TOPAZ) model, includes an advanced representation of oceanic biogeochemical cycles, providing realistic simulations of chlorophyll distribution in the Indian Ocean. The model was used to isolate the effect of wind and freshwater forcings on the upper-ocean density strati cation and identify the relative importance of different mixed layer processes in controlling the surface nutrient distribution. Biological productivity in the surface layers of the BoB is generally weak, owing to nutrient limitation imposed by strong vertical strati cation due to the presence of large freshwater in flux. However, formation of chlorophyll blooms at the surface can be ob- served in regions like the NWBoB, where the monsoonal wind forcing is favourable for upwelling. During the peak phase of the summer monsoon, the NWBoB exhibits an intense surface chlorophyll bloom, extending from the northeast coast of India to the off- shore regions. The vertical distribution of upper ocean properties and nutrient budget analysis obtained from the coupled physical-biogeochemical model reveals the dominant role of coastal upwelling driven by alongshore winds in triggering this seasonal bloom. Horizontal advection plays a secondary role by increasing the spatial extent of the surface bloom, through the supply of upwelled water from the coastal to offshore regions. The bloom decays with the weakening of surface winds and coastal upwelling by the end of the summer monsoon. Surface chlorophyll concentrations remain largely unaffected by the riverine freshwater since the river plumes are inhibited from reaching the location of the bloom due to the strong coastal upwelling. This shows that the timing and intensity of surface wind and freshwater forcings are important in determining the seasonal evolution of chlorophyll blooms in strati ed basins like the BoB. The SBoB is a highly dynamic sector, located away from the direct in uence of the riverine freshwater discharge. Surface chlorophyll distribution in the SBoB is determined by vertical mixing, strong open ocean upwelling in the region of the Sri Lanka Dome (SLD), advection by the summer monsoon current (SMC) as well as the remote in fluences associated with the westward propagating Rossby waves. The large spatial heterogeneity in the upper ocean dynamics makes the region suitable to examine the differential re- response of the vertical distribution of chlorophyll, particularly the DCM, to various mixed layer processes. The vertical shape of chlorophyll pro les is largely determined by the in- tensity and depth distribution of DCM. The Seaglider observations revealed the presence of prominent DCM in the SBoB, with high sensitivity to the variations in the upper-ocean density structure. Upwelling favoured sharp and intense DCM, leading to a pronounced vertical structure in chlorophyll. On the other hand, mixing resulted in a weaker DCM, leaving the shape of chlorophyll pro les rather diffused. Surface freshening and the as- sociated near-surface strati cation favoured the intensi cation of DCM, along with the weakening of surface chlorophyll. DCM intensi cation can be attributed to the inhibition of phytoplankton dilution under reduced vertical mixing and the relaxation in light lim- itation, as the self-shading effect of surface phytoplankton weakens. It is suggested that the persistence of DCM in the BoB is promoted by surface oligotrophy and shallow mixing. Unlike the BoB, the Arabian Sea is only weakly in uenced by freshwater from rivers, and at the same time, the surface winds are relatively stronger here. Consequently, the vertical mixing and upwelling processes are stronger in the Arabian Sea, favouring high biological productivity. The SEAS is one such region, exhibiting intense surface chloro- phyll blooms triggered by coastal upwelling off the coast of Kerala, during the peak phase of the summer monsoon. In 2016, this climatological seasonal pattern of surface chloro- phyll in the SEAS was disrupted owing to the development of an extreme negative IOD (nIOD). The region exhibited unusually high surface chlorophyll during the late boreal summer and fall intermonsoon of 2016, the highest concentrations ever reported in the region in the past two decades of the satellite era. The anomalous bloom was triggered by two cold-core eddies, along the periphery of the coastal upwelling zone. Observational evidence suggest that the eddy formation can be attributed to the local wind forcing and remote effects originating around Sri Lanka and the southern tip of India in association with the extreme nIOD. Pre-conditioning of the upper ocean induced by the seasonal shoaling of thermocline (nutricline) due to coastal upwelling during the peak monsoon phase is suggested to have a non-negligible role in favouring efficient nutrient supply to the surface layers during the eddy activity. Biological productivity in the north Indian Ocean has signi ficant climatic feedbacks, through its control on the air-sea exchanges of heat and greenhouse gases. Also, the bi- ologically productive regions of the basin support one among the world's largest marine fi shing sectors, contributing to the country's economic stability. Hence, understanding the processes underlying the chlorophyll distribution in the north Indian Ocean is climatically and economically signi ficant. The present thesis provides new insights into several un- explored aspects of chlorophyll distribution in the north Indian Ocean, pointing towards the need for extensive in situ data collection and biogeochemical modelling to better un- derstand its biophysical interactions and the associated climatic feedbacks.

In the north Indian Ocean, the Bay of Bengal (BoB or bay) and the Eastern Arabian Sea (EAS) receive a huge amount of rainfall during summer. Several rivers along their boundaries discharge enormous amounts of freshwater into the coastal regions. Strong near-surface stratification induced by rainfall and river discharge has been linked to warmer sea surface temperature (SST) of the BoB, which forms as a favourable ground for the formation and intensification of the monsoon disturbances during summer. In this thesis, the influence of rainfall and river discharge on the dynamics and thermo-dynamics of the BoB and the EAS is studied using an ocean general circulation model (OGCM). We use an eddy-permitting Indian Ocean model based on MOM4p1 (Modular Ocean Model version 4.1), with a horizontal resolution of 26 km. The vertical resolution of the model varies from 5 m in the top 60 m and the resolution gradually decreases with depth below 60m. The upper ocean hydrography and circulation of the north Indian Ocean is reproduced very well by the model. Individual and combined effects of rainfall and river discharge on the BoB is investigated using the model. A set of four sensitivity experiments, forced with same air-sea heat flux, but retaining either river runoff or rainfall or both are carried out. These experiments show that the river water is exported out of the bay along the western boundary during winter and rain water along the eastern boundary during summer. Runoff leads to a large ( >3 psu) decrease in salinity in the northern bay during summer and along the western boundary during winter, with a weaker contribution from rainfall. The East Indian Coastal Current strengthens by 10 15 cm sec 1 during winter owing to river discharge. The SST response to freshwater forcing shows large vi spatial variations with eastern bay showing higher differences. The north-western bay warms by 1.5 C in the presence of freshwater during summer, due to greater heat absorption within a shallow mixed layer (ML). This warming is caused in nearly equal proportions by rain and river water in early summer, but the contribution by river water dominates during peak and withdrawal phases of the summer monsoon. North-eastern bay, in contrast, is cooler by 1.5 3 C in the presence of freshwater, caused primarily by river runoff, owing to the winter cooling over a thin ML. Temperature inversions form due to surface cooling of a river strati ed layer during winter in the northwestern bay and due to radiation penetrating below the ML during summer in the northeastern bay. The west coast of India and the adjoining EAS is one of the high rainfall zones of Indian summer monsoon. The summer monsoon rainfall in this region is about 1036 km3, which is comparable to that of the Ganga-Brahmaputra river system. We have investigated the impact of EAS rainfall on the Arabian Sea salinity with a suite of experiments using the model. The role of low-salinity water originating in the BoB on reducing the EAS salinity has also been examined. The sea surface salinity (SSS) of EAS decreases progressively from June to September by 0.5 to 1 psu. A numerical experiment that isolates the e ect of EAS rainfall suggests that this SSS decrease is due to local rainfall. The spatial pattern of SSS decrease, however, is influenced by the prevailing West India Coastal Current. The SST in the southern EAS cools by 0.5 C in response to EAS rainfall freshening during summer. The SST cooling in the presence of salinity stratification is attributed to the enhanced upwelling along the southwest coast of India. In the southeastern Arabian Sea, during winter, the SSS decreases by about 1.5 psu. This freshening is caused by rainfall during the early winter in the southwestern BoB between 6 15 N. Neither rainfall to the north of 15 N nor river runoff into the BoB contribute much to the SEAS freshening during winter. The northern bay has been known to remain warm (>28.5 C), which favour the deep atmospheric convection, during summer. The study has been able to identify the individual and combined effects of rainfall and river discharge on the northern BoB. The near-surface salinity stratification allows the northwestern bay to remain warmer during the summer. The cooling in the northeastern bay, in the presence of freshwater forcing, points out the significance of ocean-atmosphere coupling along the eastern boundary of the bay. The local rainfall maintains the surface salinity of EAS below 36 psu throughout the year. Interestingly, the summer monsoon upwelling along the southwest coast of India is stronger in the presence of near-surface stratification induced by the EAS rainfall. The possible implications of this strong upwelling in response to local rainfall and river discharge along the west coast of India on its ecological system needs to be studied.
CSIR HOOFS

Tropical cyclones (TCs) are regarded as one of the most catastrophic meteorological and oceanic phenomena, in which the Northern Indian Ocean (NIO; including the Bay of Bengal (BoB) and the Arabian Sea (AS)) is one of the active basins worldwide. They usually result in severe property damage and significant loss of life through destructive winds, higher storm surges, torrential rains, and severe floods. The TC evolution mainly depends on multiscale airsea processes starting from largescale to synoptic to vortex scales. The NIO has unique airsea interaction due to peculiar water properties, wind systems, and mesoscale ocean and convective vortices. TCs generally form over the warm oceans where the dense network of observations is limited. These insitu observations address the temporal variability of parameters and can also be useful to validate model outputs, remote sensing data, etc. However, the scarcity of these observations limits the spatial variability assessment of airsea parameters and the representation of the ocean mesoscale vortices. The warm ocean plays a critical role in determining the genesis, intensification, maintenance, and weakening of TCs. Identifying and integrating the ocean atmospheric parameters is extremely beneficial to improve the skill of numerical models. The oceanic parameters such as tropical cyclone heat potential (TCHP), barrier layer thickness (BLT), sea surface temperature (SST), and rainfall are undergone profound spatial and temporal changes in the presence of TCs. Understanding the TC evolution response to these parameters helps in better representation of TC processes in the numerical model. However, the NIO basin lacks the baseline climatology of these parameters and hinders the numerical models’ skill. Therefore, better establishing the relationship of BL, TCHP, SST, and rainfall parameters with TC evolution by developing the composite structures helps in understanding of the TC intensification/weakening processes over the basin. The theoretical and modeling studies provided the SST effect on the TC evolution. Concurrently, the knowledge about the TC size changes and destructive potential under ocean warming conditions is limited and needs to be modelled to minimize the potential threat. The errors in initializing/defining the TCrelated circulation (vortex characteristics) from the largescale environment (global analysis) is identified as one of the reasons for model deficiency. It can overcome by providing the quality of the threedimensional information during the initial TC vortex for the improved TC predictions. The present thesis takes the opportunity to study the airsea interaction processes over the NIO basin based on observations and modeling efforts. Correspondingly, the thesis is framed starting viii from introduction to conclusion chapters along with four working chapters. The working chapters, Chapter3 and Chapter4 elaborates on the response of the TC evolution and rainfall to the ocean parametersTCHP/BL/SST. While, Chapter5 discusses the feedback response of ocean parameters to TC rainfall and wind intensity. However, it may be noted that the feedback of modified ocean parameters (SST change by the TC rainfall) is part of the results of Chapter5, but they are not exclusively studied. The SST in the model is essentially modified by the forecasted wind and rainfall, which can be seen in the temporal evolution of SST in Chapter5. The last working Chapter6 demonstrates the impact of TC vortex initialization and relocation in improving TC track, intensity, and rainfall prediction. It also reveals the importance of TC size on defining the TC initial vortex and subsequent forecast. The climatological SSTwind relation holds well over the NIO basin, except in the northern BoB, where the salinity stratification dominates and hindered it. The presence of strong ACE and its associated increase in the SST by ∼ 3−4 °C triggers an increase of (i) TCHP by ∼ 250 − 280% and (ii) enthalpy fluxes by ∼ 370% over the BoB region showing the positive feedback to the TC. The composite analysis shows that most of the TC intensification occurred when the TCHP ranging between ∼ 50 − 80 kJ cm−2 and BLT of ∼ 10 − 30 m over the BoB. The relationship of SST and TCHPA through the composite analysis revealed that VSCS and above intensity stages produce an SST cooling of >0.8 °C, TCHPA of∼ 25−30 kJ cm−2, and rainfall of >9 mm h−1 respectively. Similarly, considering the translation speed, slowmoving TCs induce a maximum SST cooling of 0.5–1.2 °C, TCHPA of 1520 k J cm−2, and rainfall of ∼ 2 − 4 mm h−1 in the TC inner core (0–100 km) region. The individual basin analysis confirms that BoB TCs produces extremely heavy rainfall (∼910 mm h−1) as compared to the AS TCs (very heavy rainfall: ∼____________7–8 mm h−1) in the inner core region. The sensitive experiments on the response of ocean warming (from 1 to 3 °C) to the TC rainfall, size, and intensity show a linear increase and whereas an exponential growth is seen in the case of destructive potential parameter to SST increase. The vortex initialization method in the ARW model improves the track, intensity, rainfall prediction of landfalling TCs Giri (2010) and Jal (2010) over the BoB. The present dissertation provides (i) a baseline for evaluating numerical models, (ii) understanding/identifying the processes that might not be modeled appropriately, (iii) information to improve vortex initialization in the coupled model environment. It is intended that these efforts helps to achieve better improvements in the TC predictions over the North Indian Ocean.

Extensive damage and loss of life can be caused by landfalling tropical cyclones (TCs). Seasonal forecasting of TC landfall probabilities is potentially beneficial to insurance/re-insurance companies, decision makers, government policy and planning departments, and residents in coastal areas. In this study, climatological and statistical seasonal forecast models are developed for TC genesis, tracks and landfall for North Indian Ocean (NIO) rim countries based on kernel density estimation, a generalised additive model (GAM) including an Euler integration step, and landfall detection using a country mask approach. To forecast TC activity in the NIO region, the relative roles of climate modes (stratospheric Quasi-Biennial Oscillation (QBO), El Niño – Southern Oscillation (ENSO), Indian Ocean Dipole (IOD)) as predictor variables in the modelling schemes have been investigated. Using a 35-year record (1979-2013) of tropical cyclone track observations from the Joint Typhoon Warning Centre (part of the International Best Track Archive Climate Stewardship Version 6), the distribution of cyclone genesis points is approximated by kernel density estimation and the observed cyclone tracks are fitted using the GAM as smooth functions of location in each season. The model simulated TCs are randomly selected from the fitted kernel (TC genesis) and cyclonic paths, with random innovations, are simulated (TC tracks) to generate a suite of landfall statistics. Lead-lag analysis is undertaken to assess the utility of various climate mode predictor timescales for TC forecast potential. Three hindcast validation methods are applied to evaluate the integrity of the models. First, leaveone-out cross-validation is applied whereby the country of landfall is determined by the majority vote (considering the location by only the highest percentage of landfall) from the simulated tracks. Second, the probability distribution of simulated landfall is evaluated against the observed landfall. Third, the distances between the point of observed landfall and simulated landfall are compared and quantified. Overall, the models show very good cross-validated hindcast skill of modelled landfalling cyclones against observations for most NIO rim countries, with only a relatively small difference in the percentage of predicted landfall locations compared with observations. Finally, the developed models demonstrate that including information on the phase of the QBO (using the stratospheric QBO index) and ENSO (using the Southern Oscillation index (SOI)) can improve the skill of seasonal forecasts of TCs in the NIO region. It is shown that the most skilful model (the model skill is assessed based on predictor leads of from 1-6 months) for ENSO as predictor is found using a three-month-averaged SOI with twomonth lead ahead of each of the four NIO region designated TC seasons. Analogously, the threemonth averaged QBO is found to be potentially most skilful at the three-month lead. Both models demonstrate clear improvements over climatology. The hindcast probabilities and distribution of TC landfall occurrences using QBO and ENSO as climate predictor modes, match remarkably well against observations over most of the study domain. Finally, in a separate analysis, a Poisson regression model using the Markov Chain Monte Carlo method was also developed to forecast TC landfall probabilities in the NIO region. A combined three-predictor (sea surface temperature, ocean heat content, and SOI) model was found to perform best in this model formulation against climatology.

Cyclonic disturbances (CDs) have a significant impact on human life, properties, and the environment. Therefore, it has been an interesting research area among researchers all over the world. Fundamental and advanced processes associated with CDs are studied by most of the researchers to understand better and thereby predict the genesis and evolution of CDs. However, the meteorological, climatological, and landfalling features associated with CDs over a particular ocean basin are quite significant to be emphasized too. This thesis provides an overview of the climatology of these fascinating storms formed over the North Indian Ocean (NIO) basin and associated rainfall, meteorological and landfalling characteristics, and other environmental features. For this purpose, TC best track data provided by India Meteorological Department (IMD) and Joint Typhoon Warning Center (JTWC), rainfall product from IMD, several parameters like sea surface temperature (SST), air temperature, surface-level relative humidity (RH), mid-tropospheric relative humidity (RH500), surface-level wind (SW), and potential evaporation factor (PEF) from International Comprehensive Ocean-Atmosphere Data Set (ICOADS), National Oceanic and Atmospheric Administration (NOAA), and Hadley centre and inter-annual oscillation indices from NOAA, the United States and Bureau of Meteorology, Australia are used. Prior to using the IMD TC best track data, the reliability of the same, and improvement by the implementation of satellite technology is discussed. The analysis indicates an improvement in the IMD best track data over the years in terms of quality, availability, and the frequency of genesis, intensity, and landfall etc. The determination of location and proper track of the CDs over NIO has improved during the satellite era, and the information related to the frequency of looping, southward moving, and recurving CDs is improvised. The percentage of the systems crossed or grazed the coast in the NIO, Bay of Bengal (BOB), and Arabian Sea (AS) basin/sub-basin is ~100% for both pre-satellite and satellite era. There has been almost robust data availability from 1961 onward with the advent of satellite technology. Based on the annual SST anomaly trend, the period of study (from 1891 onward) is divided into pre-warming (PWP; during 1880–1946) and current warming (CWP; 1947 onward) with negative and positive anomaly (trend) respectively. The Mann-Kendall test and Sen’s slope estimation indicates a decreasing trend in annual CD (total storms) and CS+SCS (cyclones and severe cyclones) frequency during CWP for NIO region and particularly BOB at 95% confidence level. However, the CD and CS+SCS frequencies were increasing during the PWP. CD activity over southern and northern BOB is decreasing sharply during CWP. The southern sector of BOB hosts mostly severe systems (intensity >48 kts) and middle sector, tropical cyclones (intensity ≥ 34 kts). CD activity over the eastern sector of AS shows considerable enhancement during CWP. Increasing SST, SW, RH500, and PEF are helpful in the formation of intensified storms during CWP. The activities during PWP were reversed compared to that of CWP. A significant temperature anomaly difference between atmosphere and ocean also perceived to play a key role in modulating the enhanced intensity of TCs during CWP. The SST range of 27.5 to 29.5 °C and the supportive flow field is helping to enhance the middle and upper tropospheric moisture content; eventually, resulting in increased SST, PEF, and RH through a possible feedback mechanism. The trend for vertical wind shear is decreasing, supporting a higher rate of intensification of depressions to severe ones. The impact of the warming climate on landfall activity reveals that Bangladesh (BD), Andhra Pradesh (AP), and Tamil Nadu (TN) are more vulnerable to severe cyclones formed over BOB during the CWP. Among western coastal states, Gujarat (GJ) is prone to SCS, and Arabian Peninsula countries are vulnerable to CS formed over the AS during the current warming climate as well. During CWP, BD and Arakan are more vulnerable to CD landfall in the pre-monsoon season, whereas in post-monsoon months, AP, TN, and BD are more prone coastal areas of BOB. The enhanced genesis over the southern and middle sector of BOB is mainly responsible for more landfall over AP, TN, and BD. The seasonal analysis of change in genesis location of CDs during PWP and CWP over BOB and AS agrees well with the landfall point of CDs. Also, changes in wind direction from NW to N-NW and increased meridional SST over BOB found to be encouraging the landfall activity near AP and TN coasts. The W-SW and zonally distributed SST supports landfall over Gujarat. There is less impact of change in genesis location over AS landfalling CDs. The destruction potential of CDs in terms of accumulated cyclone energy (ACE) during recent years is observed to be increasing as the rate of intensification of CDs has increased over NIO. Every year, CDs cause destruction along the coastal areas of the world basins by pouring heavy rainfall, which causes floods and landslides. By using high-quality daily rainfall data, the contribution of rainfall by NIO CDs over India was also investigated. Among eastern coastal states, the accumulated rainfall is higher over AP, TN, Odisha (OD), and southern West Bengal (WB) during pre-monsoon season. Among western coastal states, Karnataka (KA) and Kerala (KL) suffer maximum rainfall from CDs. During the post-monsoon season, coastal AP, TN, OD, KA, and coastal KL received higher accumulated rainfall. Gujarat received ~70%, and both AP and TN received up to 20-30% of rainfall by CDs during pre-monsoon months. In most of the states, the overall rainfall contribution by CDs is observed to have a decreasing trend during both seasons. Owing to the stable rainfall trend along with decreasing CD frequency during the post-monsoon season, the results indicate an increased amount of rainfall contribution by CDs during the season. CDs contribute a considerable amount of rainfall to central and northern India during the post-monsoon season. Further, the rainfall contribution by CDs during El-Nino southern Oscillation (ENSO), Indian Ocean Dipole (IOD), and Madden-Julian Oscillation (MJO) under the impact of the warming climate emphasized for both NIO TC sessions. The accumulated rainfall observed to be high over AP and OD during the events considered in pre-monsoon season except for the La-Nina event where rainfall is high over GJ. During the post-monsoon season, the accumulated rainfall is high over AP, OD, and TN. In terms of annual variations, the annual CD days are low; however, the annual average rainfall is high for MJO periods during pre-monsoon season. La-Nina periods contributed second highest annual average CD rainfall during pre-monsoon season. For the post-monsoon season, negative IOD and La-Nina contributed higher CD rainfall, and the maximum CD days also observed to be higher. A significant amount of CD attributed rainfall is observed during a positive IOD event, and the same is also confirmed by the principal component analysis. The WRF regional analyses showed that CD rainfall in both seasons is relatively lower than the observations, but the spatial distribution is reasonably well predicted. From the study carried out in this thesis, it is quite evident that the warming climate has an adverse impact on CD genesis over NIO. The decrease in the number of CDs with an increased rate of intensification in the changing climate scenario poses a threat to society. And, the increased rainfall by CDs during post-monsoon is also causing massive destruction in recent years.

In British Columbia, fifty-one First Nations have filed Statements of Intent signifying their interest in negotiating a treaty with Canada and the Province of British Columbia since the establishment of the British Columbia Treaty Commission in 1993. Twenty-seven of these First Nations participants claim ocean spaces within their traditional territories. Academic research and writing over the last decade has focussed on Aboriginal title to land, with little, if any reference, to ocean spaces. The concept of Aboriginal title was recently recognized by the courts in Delgamuukw v. British Columbia. My research will explore what information and legal principles could be utilized to recognize Aboriginal title to ocean spaces within the Canadian legal context, and therefore provide some bases for First Nations in substantiating their claims. My analysis will begin with a review of international law principles surrounding title to and jurisdiction over ocean spaces. Following which, I will delineate the sources available for recognizing such a theory, starting with a review of the concepts of Aboriginal title as determined in Delgamuukw and their applicability to ocean spaces. Delgamuukw has affirmed Aboriginal perspectives are an integral part of the investigation of Aboriginal title, and voices of members of two particular First Nations being the Haida Nation and the Tsawwassen First Nation, with whom I visited, will be included. Rounding out the sources will be a review of comparative legal concepts drawn from the United States and Australian experiences, and the principles espoused within international human rights materials. Having established the avenues for recognition of this concept, I then turn to discussion of its reconciliation within the Canadian legal context by reviewing theories of co-management and examining a number of settlement instruments that have yielded some degree of reconciliation between the federal government and the particular First Nation or Province involved. Comments from First Nations in respect of the obstacles that hold back reconciliation will be noted. In conclusion, my research will deduce Aboriginal title to ocean spaces is a viable legal concept in Canada, and First Nations have the resources necessary to substantiate their claims. Comments about the possibilities that may result at the treaty table or in the courts upon recognition of this concept will also be discussed. This analysis is timely and important as many First Nations are nearing the stage of the treaty process where discussions will be directed towards what territories these First Nations groups will retain and what ownership, jurisdiction and rights they will enjoy as to ocean spaces and resources. Such issues directly relate to the continued way of life, culture, and sustainable economic growth and stability of First Nation communities into the twenty-first century.

Summer monsoon current (SMC) in the north Indian Ocean (NIO) is an open ocean current that flows eastward and enter into Bay of Bengal (BoB) during southwest monsoon (June–September). South of Sri Lanka, the SMC turns north-eastward instead of following eastward course and feeds into the BoB. Understanding the dynamics of SMC is crucial to understanding the interaction between Arabian sea (AS) and BoB. In the year 2009, the current moved north-eastward, meandered and then finally terminated into the southeast BoB. The northward bend of the current southeast of Sri Lanka has been attributed to the interaction of the eastward SMC with Rossby waves radiated from eastern boundary. An anticyclonic vortex formed right of the north-eastward meandering current which was associated with significantly high speeds. Reasons behind the unusually high speeds of SMC in this region remain unknown. Processes involved in the interaction of eddies with eastward SMC, the meandering of the current and its ultimate termination in southeast BoB are also not understood. Our study investigates the evolution, intensfication and meandering of SMC around Sri Lanka using an Indian Ocean general circulation model (MOM4p1) simulation for the year 2009. The model simulation, when compared with observational data OSCAR, showed good agreement. The study also explores the role of local and remote forcing in modulating the dynamics of SMC in the region. An eddy kinetic energy budget analysis for the region was performed which indicates the region to be a zone of significant eddy activity. Both barotropic, baroclinic instabilities were found to be the dominant mechanisms behind the generation of eddies. Based on eddy energetic analysis, the evolution of SMC was classified into stages i ii of onset, intensification, anticyclonic bend, anticyclonic vortices formation and meandering. Effect of eddies on mean flow were studied with the help of a transformed Eulerian mean (TEM) approach under quasi-geostrophic approximation. Eddy potential vorticity fluxes appearing in the TEM momentum equation and eddy enstrophy decay, divergence of eddy enstrophy advection from eddy enstrophy equation, helped to un-derstand when, where and how the eddies tended to drive the mean flow. Rossby waves and other westward propagating eddies arriving from the east, energise the SMC in June and induce an acceleration tendency on the mean flow through regions associated with upgradient eddy potential vorticity flux. In addition to the eddies, local winds also play a crucial role in driving the mean flow. Wind power, surface mean ocean kinetic energy and available potential energy (APE) were computed, integrated over the region of interest and compared to each other. The effect of local winds appear to be predominant in driving the mean flows as it not only increases the surface mean kinetic energy of the SMC but also raises the isopycnals and builds up large amount of APE in the ocean. Baroclinic instability takes place in late July and early August associated with the release of APE which flattens the isopycnals and thus weakens the SMC. Consequently the SMC meanders in course of time and flows into southeast BoB.

Summer monsoon current (SMC) in the north Indian Ocean (NIO) is an open ocean current that flows eastward and enter into Bay of Bengal (BoB) during southwest monsoon (June–September). South of Sri Lanka, the SMC turns north-eastward instead of following eastward course and feeds into the BoB. Understanding the dynamics of SMC is crucial to understanding the interaction between Arabian sea (AS) and BoB. In the year 2009, the current moved north-eastward, meandered and then finally terminated into the southeast BoB. The northward bend of the current southeast of Sri Lanka has been attributed to the interaction of the eastward SMC with Rossby waves radiated from eastern boundary. An anticyclonic vortex formed right of the north-eastward meandering current which was associated with significantly high speeds. Reasons behind the unusually high speeds of SMC in this region remain unknown. Processes involved in the interaction of eddies with eastward SMC, the meandering of the current and its ultimate termination in southeast BoB are also not understood. Our study investigates the evolution, intensfication and meandering of SMC around Sri Lanka using an Indian Ocean general circulation model (MOM4p1) simulation for the year 2009. The model simulation, when compared with observational data OSCAR, showed good agreement. The study also explores the role of local and remote forcing in modulating the dynamics of SMC in the region. An eddy kinetic energy budget analysis for the region was performed which indicates the region to be a zone of significant eddy activity. Both barotropic, baroclinic instabilities were found to be the dominant mechanisms behind the generation of eddies. Based on eddy energetic analysis, the evolution of SMC was classified into stages i ii of onset, intensification, anticyclonic bend, anticyclonic vortices formation and meandering. Effect of eddies on mean flow were studied with the help of a transformed Eulerian mean (TEM) approach under quasi-geostrophic approximation. Eddy potential vorticity fluxes appearing in the TEM momentum equation and eddy enstrophy decay, divergence of eddy enstrophy advection from eddy enstrophy equation, helped to un-derstand when, where and how the eddies tended to drive the mean flow. Rossby waves and other westward propagating eddies arriving from the east, energise the SMC in June and induce an acceleration tendency on the mean flow through regions associated with upgradient eddy potential vorticity flux. In addition to the eddies, local winds also play a crucial role in driving the mean flow. Wind power, surface mean ocean kinetic energy and available potential energy (APE) were computed, integrated over the region of interest and compared to each other. The effect of local winds appear to be predominant in driving the mean flows as it not only increases the surface mean kinetic energy of the SMC but also raises the isopycnals and builds up large amount of APE in the ocean. Baroclinic instability takes place in late July and early August associated with the release of APE which flattens the isopycnals and thus weakens the SMC. Consequently the SMC meanders in course of time and flows into southeast BoB.