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1
JOSEPH, P. V. "Monsoon variability in relation to equatorial trough activity over Indian and West Pacific Oceans." MAUSAM 41, no. 2 (February 22, 2022): 150–55. http://dx.doi.org/10.54302/mausam.v41i2.2560.
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Variability of Indian monsoon rainfall has been examined in relation to the convective activity of the equatorial trough over the Indian Ocean a~d the Pacific Qcean west of the International Date Line. It is found that the cyclogenesis (tropical cyclones) near the West Pacific equatorial trough is closely related to this variability through a see-saw in. convection between this ocean basin and north Indian Ocean, with period in the range 30-50 days. SST anomalies over north Indian Ocean and West Pacific Ocean can cause variability of the date of onset of monsoon and also the quantum of monsoon rainfall over India through the 30-50 day mode.
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Zhou, Zhen-Qiang, Renhe Zhang, and Shang-Ping Xie. "Interannual Variability of Summer Surface Air Temperature over Central India: Implications for Monsoon Onset." Journal of Climate 32, no. 6 (February 18, 2019): 1693–706. http://dx.doi.org/10.1175/jcli-d-18-0675.1.
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Abstract Year-to-year variability of surface air temperature (SAT) over central India is most pronounced in June. Climatologically over central India, SAT peaks in May, and the transition from the hot premonsoon to the cooler monsoon period takes place around 9 June, associated with the northeastward propagation of intraseasonal convective anomalies from the western equatorial Indian Ocean. Positive (negative) SAT anomalies during June correspond to a delayed (early) Indian summer monsoon onset and tend to occur during post–El Niño summers. On the interannual time scale, positive SAT anomalies of June over central India are associated with positive SST anomalies over both the equatorial eastern–central Pacific and Indian Oceans, representing El Niño effects in developing and decay years, respectively. Although El Niño peaks in winter, the correlations between winter El Niño and Indian SAT peak in the subsequent June, representing a post–El Niño summer capacitor effect associated with positive SST anomalies over the north Indian Ocean. These results have important implications for the prediction of Indian summer climate including both SAT and summer monsoon onset over central India.
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S. N. PANDEY, R. BHATLA, MANOJ K. SRIVASTAVA, and R. K. MALL. "Floods and hazardous heavy rainfall in India: Comparison between local versus oceanic impact." Journal of Agrometeorology 12, no. 1 (June 1, 2010): 40–43. http://dx.doi.org/10.54386/jam.v12i1.1265.
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India, leading to heavy rainfall. Such heavy rainfall result in floods for wider region of northern India, and, which, finally, causes loss of agriculture, human and animal’s life, outbreak of diseases/ epidemics, and thus affecting national economy. An attempt has therefore, been made to analyze the disastrous events that occurred in the summer monsoon months over different states in India for the period 1981-2000. The analyses included the raining event which were active, but, caused due to- or without the monsoonal-systems that were formed in north Indian Ocean. Results showed that West Bengal was the mostly affected state during monsoon season, where both, local as well as monsoonal systems were equally responsible for heavy rainfall/ flood events. The local atmospheric phenomenon affected highly to Uttar Pradesh, West Bengal, Gujarat, and Maharashtra, whereas for systems that were associated with the north Indian Ocean and Bay of Bengal, the states of West Bengal and Orissa were the mostly affected states. From the study, it may be concluded that all the heavy rainfall related disastrous weather events formed over different states in India was not only due to systems developed over Oceans, rather, local atmospheric phenomena had equally important contributor of similar affects, particularly for northern and western India.
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JOSEPH, PV, and PV PILLAI. "Air-sea interaction on a seasonal scale over north Indian Ocean -Part II. : Monthly mean atmospheric and oceanic parameters during 1972 and 1973." MAUSAM 37, no. 2 (April 11, 2022): 159–68. http://dx.doi.org/10.54302/mausam.v37i2.2217.
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Monsoon-Indian Ocean interaction is examined in detail using 5-dcgree square monthly mean data of ocean and atmosphere of two consecutive years of contrasting monsoon rainfall, 1972 and 1973. There was a major monsoon failure (drought) in 1972; in 1973 India had excess rainfall during the monsoon season.
It is found that north Indian Ocean is colder than normal (negative SST anomaly) during the months prior to monsoon of 1972" During this –period upper tropospheric sub-tropical westerlies (monthly mean) intruded equatorwards over soJ1tlfAsia, farthest south over the Arabian Sea longitudes. The weak monsoon of June to Septemb~72 produced a warm SST anomaly over tropical Indian Ocean on account of decreased cooling of the ocean surface layer during the monsoon season due to decreased upwelling, particularly off the coasts of Somalia and Arabia, decreased wind mixing, decreased evaporation, and decreased clo1.lding. The positive SST anomaly of large spatial extent thus created persisted from October 1972 to May 19-73. The upper tropospheric circulation over south Asia during this period had equatorial easterlies (instead of westerlies) and increased strength of the sub-tropical westerly jet stream over north India. These results agree with observations and GCM simulations over Pacific Ocean with warm SST anomalies. Monsoon of 1973 was good and cold SST anomalies again appeared over north Indian Ocean from October 1973.
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Brown, J., C. A. Clayson, L. Kantha, and T. Rojsiraphisal. "North Indian Ocean variability during the Indian Ocean dipole." Ocean Science Discussions 5, no. 2 (June 9, 2008): 213–53. http://dx.doi.org/10.5194/osd-5-213-2008.
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Abstract. The circulation in the North Indian Ocean (NIO henceforth) is highly seasonally variable. Periodically reversing monsoon winds (southwesterly during summer and northeasterly during winter) give rise to seasonally reversing current systems off the coast of Somalia and India. In addition to this annual monsoon cycle, the NIO circulation varies semiannually because of equatorial currents reversing four times each year. These descriptions are typical, but how does the NIO circulation behave during anomalous years, during an Indian Ocean dipole (IOD) for instance? Unfortunately, in situ observational data are rather sparse and reliance has to be placed on numerical models to understand this variability. In this paper, we estimate the surface current variability from a 12-year hindcast of the NIO for 1993–2004 using a 1/2° resolution circulation model that assimilates both altimetric sea surface height anomalies and sea surface temperature. Presented in this paper is an examination of surface currents in the NIO basin during the IOD. During the non-IOD period of 2000–2004, the typical equatorial circulation of the NIO reverses four times each year and transports water across the basin preventing a large sea surface temperature difference between the western and eastern NIO. Conversely, IOD years are noted for strong easterly and westerly wind outbursts along the equator. The impact of these outbursts on the NIO circulation is to reverse the direction of the currents – when compared to non-IOD years – during the summer for negative IOD events (1996 and 1998) and during the fall for positive IOD events (1994 and 1997). This reversal of current direction leads to large temperature differences between the western and eastern NIO.
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SINGH, O. P. "The association between the north Indian Ocean and summer monsoon rainfall over India." MAUSAM 49, no. 3 (December 17, 2021): 325–30. http://dx.doi.org/10.54302/mausam.v49i3.3638.
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Utilizing the marine meteorological data of the period 1961-81, the sea level pressure (SLP) and sea surface temperature (SST) distributions have been obtained on a 5° grid-mesh over the north Indian Ocean area bounded by 0°- 25°N, 50°- l00°E for each individual year. It has been found that the SLP and SST fields for the month of May provide predictive indications of subsequent summer monsoon rainfall over India. Significant negative correlations have been found between the mean SLPs of May over the latitudinal belts 5°-10°, 10°- 15°, 15°-20° and 20°-25°N of Arabian Sea and Bay of Bengal and all India rainfall departures of succeeding summer monsoon season. The mean SST gradient over the Arabian Sea between 7.5°- 17 .5°N during May has been found to have significant positive correlation with all India rainfall of subsequent monsoon. The study suggests that certain functions of SLP and SST of May over the north Indian Ocean can prove to be useful predictors for subsequent summer monsoon rainfall over India.
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MOHAPATRA, M., and S. ADHIKARY. "Modulation of cyclonic disturbances over the north Indian Ocean by Madden - Julian oscillation." MAUSAM 62, no. 3 (December 14, 2021): 375–90. http://dx.doi.org/10.54302/mausam.v62i3.316.
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The relationship of genesis and intensity of cyclonic disturbances (CDs) over the north Indian Ocean with the Madden – Julian Oscillation (MJO) has been examined using 33 years (1975 - 2007) data of MJO index and best track of (CDs) developed by India Meteorological Department (IMD). The MJO index based on outgoing long wave radiation (OLR) and zonal wind in upper (200 hPa) and lower (850 hPa) troposphere (Wheeler and Hendon, 2004) has been used for this purpose.
The MJO strongly modulates the genesis and intensity of CDs over the north Indian Ocean. However there are other factors contributing to cyclogenesis over the north Indian Ocean, as about 60% of cyclogenesis during monsoon and post-monsoon seasons are not significantly related with MJO. While the probability of cyclogenesis during monsoon season is higher with MJO in phase 4 and 5 (Maritime Continent), that during post-monsoon season is higher with MJO in phase 3 and 4 (east Indian Ocean and adjoining Maritime Continent). It indicates that while possibility of genesis during monsoon season is significantly suppressed with active MJO at phase 1, 7 and 8 (Africa, western Hemisphere and adjoining Pacific Ocean), there is no significant relationship between genesis and active MJO at phase 1, 7 and 8 during post-monsoon season. The anomalous cyclonic circulation at lower levels over central and north Bay of Bengal in association with MJO at phase 4 and 5 favours enhanced probability of cyclogenesis over the Bay of Bengal during monsoon season. The anomalous easterlies in association with MJO at phase 1 and development of anomalous ridge over south India in association with MJO at phase 7 and 8 which are weak monsoon features lead to suppressed cyclogenesis over north Indian Ocean during this season. The anomalous north-south trough in easterlies embedded with cyclonic circulation over the south west/west central Bay of Bengal in association with southerly surge over the region during active MJO in phase 3 and 4 most favourably influences the convection and enhances the probability of cyclogenesis over the north Indian Ocean during post-monsoon season.
The genesis of CDs is more sensitive to phase than the amplitude while the intensification of CDs is more dependent on the amplitude of MJO. Comparing monsoon and post-monsoon seasons, the modulation of genesis, intensification and duration of CDs by the MJO is more during the monsoon season than the post-monsoon season.
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SARKAR, PARTHAPRATIM, PRASHANTH JANARDHAN, and PARTHAJIT ROY. "Indian Ocean Dipole : Assessing its impacts on the Indian Summer Monsoon Rainfall (ISMR) across North East India." MAUSAM 72, no. 4 (November 1, 2021): 821–34. http://dx.doi.org/10.54302/mausam.v72i4.3550.
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The Indian Ocean Dipole (IOD), a climatic anomaly, results in sustained sea surface temperature (SST) variations between tropical western and eastern Indian Ocean temperatures. In this study, we studied the variations to inculcate the teleconnections between IOD and Indian summer monsoon rainfall (ISMR) distribution across the country for the period 1960-2020 for all the three phases of ISMR. We analyzed rainfall, SST and low-level wind circulation anomalies for the above mentioned time horizon. Positive IOD events noticeably resulted in increase in summer monsoon rainfall distribution across the country respectively while its negative counterpart led to decrease in rainfall except for the commencement phase of ISMR. The variations in SST, wind circulation and moisture movement processes across the Indian Ocean characterize significant changes in rainfall during the positive and negative phases of IOD especially during the recent decades (1991-2020). The recent time horizon also witnesses enhanced low-level equatorial jets (LEJ) across the equatorial Indian Ocean and the Arabian Sea during the positive IOD events as compared to the prior decades (1960-1990). The effect of moisture convergence zone is also analyzed which results in above rainfall conditions across northeastern and central India. Conversely, negative IOD events were found to subdue any such moisture movement mechanisms. Furthermore, and additional investigation to analyze the effect of IOD on the retreating/withdrawal monsoon across northeast India has been done and it has been observed that a stronger positive IOD is detrimental to the seasonal rainfall (May- September) over North East India (-0.7 one month lag correlation). Furthermore, the DMI index of April-May presented a clear indication of monsoon activity over the area during the withdrawal or retreating phase of the summer monsoon, i.e., during September.
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SARKAR, PARTHAPRATIM, PRASHANTH JANARDHAN, and PARTHAJIT ROY. "Indian Ocean Dipole : Assessing its impacts on the Indian Summer Monsoon Rainfall (ISMR) across North East India." MAUSAM 72, no. 4 (November 10, 2021): 821–34. http://dx.doi.org/10.54302/mausam.v72i4.597.
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The Indian Ocean Dipole (IOD), a climatic anomaly, results in sustained sea surface temperature (SST) variations between tropical western and eastern Indian Ocean temperatures. In this study, we studied the variations to inculcate the teleconnections between IOD and Indian summer monsoon rainfall (ISMR) distribution across the country for the period 1960-2020 for all the three phases of ISMR. We analyzed rainfall, SST and low-level wind circulation anomalies for the above mentioned time horizon. Positive IOD events noticeably resulted in increase in summer monsoon rainfall distribution across the country respectively while its negative counterpart led to decrease in rainfall except for the commencement phase of ISMR. The variations in SST, wind circulation and moisture movement processes across the Indian Ocean characterize significant changes in rainfall during the positive and negative phases of IOD especially during the recent decades (1991-2020). The recent time horizon also witnesses enhanced low-level equatorial jets (LEJ) across the equatorial Indian Ocean and the Arabian Sea during the positive IOD events as compared to the prior decades (1960-1990). The effect of moisture convergence zone is also analyzed which results in above rainfall conditions across northeastern and central India. Conversely, negative IOD events were found to subdue any such moisture movement mechanisms. Furthermore, and additional investigation to analyze the effect of IOD on the retreating/withdrawal monsoon across northeast India has been done and it has been observed that a stronger positive IOD is detrimental to the seasonal rainfall (May- September) over North East India (-0.7 one month lag correlation). Furthermore, the DMI index of April-May presented a clear indication of monsoon activity over the area during the withdrawal or retreating phase of the summer monsoon, i.e., during September.
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Kabir, Rubaiya, Elizabeth A. Ritchie, and Clair Stark. "Tropical Cyclone Exposure in the North Indian Ocean." Atmosphere 13, no. 9 (September 2, 2022): 1421. http://dx.doi.org/10.3390/atmos13091421.
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The North Indian Ocean is a region with a high coastal population and a low-lying delta, making it a high-risk region for tropical cyclone impacts. A 30-year period from 1989–2018 has been used to examine the TC landfalling exposure in the North Indian Ocean and its changes by considering 30 years of IBTrACs data, ERA5 atmospheric data, and 20 years of TRMM and DAV data. A total of 185 TCs made landfall in the NIO during the 30-year period with the majority of the TCs making landfall during the pre- and post-monsoon seasons. Rainfall associated with landfalling TCs decreased in the last 10 years of analysis (2009–2018) compared to the first 10 years of available data from 1999–2008. During the monsoon, TC activity is relatively lower compared to the post-monsoon periods, even though higher accumulated TC-associated rainfall typically occurs during the monsoon period, particularly along the eastern coastlines of the Arabian Sea and the Bay of Bengal. The TC winds impact most of the Bay of Bengal coastline, including Sri Lanka. The spatial distribution of landfalling TCs changes with the season, with most of the landfalling activity occurring during the pre- and post-monsoon periods. Interestingly, more recent TC activity has shifted to the northeast India and Bangladesh coasts, suggesting that these regions may be more vulnerable to TC impacts in the future.
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Anderson, R. Charles. "Do dragonflies migrate across the western Indian Ocean?" Journal of Tropical Ecology 25, no. 4 (July 2009): 347–58. http://dx.doi.org/10.1017/s0266467409006087.
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Abstract:In the tropical Indian Ocean, the Maldive Islands lack surface freshwater, so are unsuitable for dragonfly reproduction. Nevertheless, millions of dragonflies (Insecta, Odonata; mostly globe skimmer, Pantala flavescens) appear suddenly every year starting in October. Arrival dates in the Maldives and India demonstrate that the dragonflies travel from southern India, a distance of some 500–1000 km. Dates of arrival and occurrence coincide with the southward passage of the Inter-tropical Convergence Zone (ITCZ). Circumstantial evidence suggests that the dragonflies fly with north-easterly tail winds, within and behind the ITCZ, at altitudes over 1000 m. It is proposed that this massive movement of dragonflies is part of an annual migration across the western Indian Ocean from India to East Africa. Arrival dates in the Seychelles support this hypothesis. Dragonflies also appear (in smaller numbers) in the Maldives in May, with the onset of the southwest monsoon, suggesting a possible return migration from Africa. These proposed migrations of dragonflies, regularly crossing 3500 km or more of open ocean, were previously unknown. It is known that these dragonflies exploit ephemeral rain pools for reproduction; the monsoons and ITCZ bring not only alternating, seasonal rains to India and Africa, but also appropriate winds for dragonflies to follow those rains. Several bird species migrate from India across the western Indian Ocean to wintering grounds in Africa. They do so at the same time as the dragonflies, presumably taking advantage of the same seasonal tail winds. Many of these birds also eat dragonflies; the possible significance of this was not previously appreciated.
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Chung, Chul Eddy, and V. Ramanathan. "Weakening of North Indian SST Gradients and the Monsoon Rainfall in India and the Sahel." Journal of Climate 19, no. 10 (May 15, 2006): 2036–45. http://dx.doi.org/10.1175/jcli3820.1.
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Abstract Sea surface temperatures (SSTs) in the equatorial Indian Ocean have warmed by about 0.6–0.8 K since the 1950s, accompanied by very little warming or even a slight cooling trend over the northern Indian Ocean (NIO). It is reported that this differential trend has resulted in a substantial weakening of the meridional SST gradient from the equatorial region to the South Asian coast during summer, to the extent that the gradient has nearly vanished recently. Based on simulations with the Community Climate Model Version 3 (CCM3), it is shown that the summertime weakening in the SST gradient weakens the monsoon circulation, resulting in less monsoon rainfall over India and excess rainfall in sub-Saharan Africa. The observed trend in SST is decomposed into a hypothetical uniform warming and a reduction in the meridional gradient. The uniform warming of the tropical Indian Ocean in the authors’ simulations increases the Indian summer monsoon rainfall by 1–2 mm day−1, which is opposed by a larger drying tendency due to the weakening of the SST gradient. The net effect is to decrease the Indian monsoon rainfall, while preventing the sub-Saharan region from becoming too dry. Published coupled ocean–atmosphere model simulations are used to describe the competing effects of the anthropogenic radiative forcing due to greenhouse gases and the anthropogenic South Asian aerosols on the observed SST gradient and the monsoon rainfall.
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Perez, Rosa Maria. "Subalternity across the Indian Ocean: the Sidis of Gujarat." Asian Review of World Histories 8, no. 1 (February 6, 2020): 61–82. http://dx.doi.org/10.1163/22879811-12340064.
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Abstract In Gujarat, as in other states of India, the Sidis illustrate the long-term African existence in India, which was dominantly analyzed through Eurocentric categories substantiated either by the semantics of slavery or, more recently, by the paradigm of the African diaspora in the world. Both were mainly produced in and for the North Atlantic realm. This article aims at identifying the intersection between the two margins of the Indian Ocean grounded on an ethnohistory of the Sidis of Gir, in Saurashtra. As an anthropologist, it is at the level of contemporary Indian society within the dialectic and dialogic framework of relationships between the Sidis and the other groups that I observed them, being aware of the discontinuities existing within this category on the one hand and, on the other, of a common idiom through which the Sidis communicate their “Africanness.”
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GOYAL, SUMAN, M. MOHAPATRA, PRIYANKA KUMARI, S. K. DUBE, and KUSHAGRA RAJENDRA. "Validation of Advanced Dvorak Technique (ADT) over north Indian Ocean." MAUSAM 68, no. 4 (December 2, 2021): 689–98. http://dx.doi.org/10.54302/mausam.v68i4.768.
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The Advanced Dvorak Technique (ADT) has been installed in India Meteorological Department experimentally since 2014. There is a need to validate this technique before it’s used operationally. Hence a study has undertaken to validate ADT (V8.1.3B) & ADT (V8.2.1) based on all the TCs (34 Knots & above) over the North Indian Ocean during 2014 & 2015 (total 7 no.). The performance of ADT has been compared with manual T number. It indicates that ADT (V8.2.1) overestimates by about 1 T number as compared to manual T number of 1.0 to 2.5 and underestimates by about 0.5 to 1 T number as compared to manual T number of 4.0 to 5.5. Further comparison with CIMSS ADT indicates that IMD ADT underestimates by about 1 T number compared to T number based on CIMSS ADT.
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Bhattacharya, Sumanta, Jayanta Kumar Ray, Shakti Sinha, and Bhavneet Kaur Sachdev. "THE GROWING RELATION BETWEEN CHINA AND PAKISTAN AND ITS INFLUENCE ON INDIA AND ITS CHALLENGES AHEAD." International journal of multidisciplinary advanced scientific research and innovation 1, no. 9 (November 29, 2021): 184–89. http://dx.doi.org/10.53633/ijmasri.2021.1.9.04.
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China and Pakistan diplomatic relation started from 1951 which has grown over the years. China is providing humongous weapons, aircrafts and submarines to Pakistan in spite Pakistan being in debt and now Turkey has also started to provide military weapons to Pakistan, the ultimate aim to is attack India .The string of pearls is a geopolitical strategic to surround Indian peninsular from all sides by creating naval base in its neighbor countries .The economic corridor of China and Pakistan is also a weapon to keep a check on India and amplify Pakistan influence in the Indian Ocean region by providing them powerful submarines. However due to China’s belt and road initiative project which is one of the most financial risk projects has made china lost its appetite to provide money for large infrastructure projects especially in Pakistan, the disagreement between Pakistan and China on CPEC has stopped the work ahead. China is also supporting the Maoist, North- East insurgency and terrorist groups in India by providing those arms and has also attacked India through Cyber warfare. China through the string of pears, CPEC, Belt and Road initiative is trying to encircle India. Keyword: China, Pakistan, India, CPEC, String of pears, military, diplomatic relations, Indian Peninsula, Indian Ocean
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Hanim, Nisfa, Yusli Wardiatno, Dyah Perwitasari, Ali Suman, and Achmad Farajallah. "New record of Charybdis goaensis (Decapoda: Brachyura: Portunidae) in Indonesia." BIO Web of Conferences 19 (2020): 00010. http://dx.doi.org/10.1051/bioconf/20201900010.
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The first report of Charybdis goaensis Padate, Rivonker, Anil, Sawant & Krishnamurthy, 2010 was from Goa, India in 2010 year. Its occurrence in Indonesia is the second report in the world. The samples were harvested by a fisherman in Sibolga city and Natal district-Mandailing Natal Regency, North Sumatera. We recorded three males and ten females of Charybdis goaensis, which consists of juveniles and ovigerous females. Both sampling locations are in one coastline in west coast Sumatera which faces directly to the Indian Ocean. We assumed that the dispersal of this species through the Indian Ocean is at their larval phase.
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Seshan, Radhika. "Intersections: Peoples, ports and trade in seventeenth-century Surat and Madras." International Journal of Maritime History 29, no. 1 (February 2017): 111–22. http://dx.doi.org/10.1177/0843871416679118.
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The article discusses the ways in which, in the seventeenth century, as India drew the attention of more Europeans, both as private traders and as part of larger east India companies, networks of contacts were established. Two ports in particular, Surat and Madras (now Chennai), became points of intersection of Europeans and Asians, through the multi-pronged trade networks that linked these two ports to other ports in the Indian Ocean world, through traders from across regions. Focus is on the English in particular, as their main port of trade for Mughal North India was Surat, and Madras, their first fortified establishment on the coast of India.
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Asif, Dr Muhammad. "Blue Economy and Power Politics in the Indian Ocean: Challenges and Opportunities." Journal of Nautical Eye and Strategic Studies 2, no. 2 (March 12, 2023): 2–37. http://dx.doi.org/10.58932/mulg0003.
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In order to meet the future global economic challenges, the understanding of the dynamics of the Oceans, in terms of trading aspect, is as essential for the international states as Oxygen is important for the survival of the human beings. This study is an effort to explore the Indian Ocean in the context of "Blue Economy". The Indian Ocean has been presented by the maritime strategists, as an important alternate option, in terms of the increasing dependency of the Middle East, Africa, and Asia on natural resource flows. As being the third-largest ocean in the world, it has grown its’ significance in global politics over the past three decades. It has unique geographic structure, bounded by Australia toward the South-East, Africa in the West and Asia in the North and East. Inspite of enjoying substantial size, expanding population and abundant natural resources, it has long been comparatively neglected in global geopolitics by the superpowers in 20th century. But now, rapidly growing economic challenges compelled the international states to take the Indian Ocean from economic perspective. The objectives of the study are to examine the dynamics of the Indian Ocean from both strategic and economic perspectives, to highlight the challenges, facing by China and Pakistan as a result of the Indian Maritime Strategy in the Indian Ocean and the presence of US naval forces there and finally, to identify those areas where Pakistan-China might be able to take advantage of the Indian Ocean, in the perspective of the Blue Economy. The qualitative study has been grounded, based on secondary data by applying the theory of balance of power. Finally, it offered some recommendations for China and Pakistan regarding how to address the problems that the US and India have placed in the Indian Ocean.
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KHOLE, MEDHA. "Inter-annual and decadal variability of sea surface temperature (SST) over Indian Ocean." MAUSAM 56, no. 4 (January 20, 2022): 803–10. http://dx.doi.org/10.54302/mausam.v56i4.1036.
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With the discovery of a dipole in Indian Ocean Sea Surface Temperature (SST), the Indian Ocean has been gaining an increasing importance in the context of global climate. SST is one of the important oceanic parameters controlling the ocean climate. In view of this importance, an attempt has been made in this study to examine the inter-annual and inter-seasonal variability of SST over (i) Equatorial Indian Ocean (5° N - 5° S and 50° E - 100° E) and (ii) North Indian Ocean (5° N - 20° N and 50° E - 100° E), during the period 1961-98. The values of seasonal SST anomaly over these sectors of Indian Ocean are computed for the four standard meteorological seasons over India, viz., Winter (January - February), Pre-monsoon (March - May), SW Monsoon (June - September) and Post-Monsoon (October - December). The variability of seasonal SST anomaly is examined, using various standard statistical methods and procedures, on inter-annual as well as decadal time-scale and the results are inter-compared. The SST anomaly over both the above sectors of Indian Ocean, for all the four seasons, shows an increasing trend during 1961-98, more particularly and prominently, after mid-1970s.
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BACHIOCHI, DAVID, BHASKAR JHA, and T. N. KRISHNAMURTI. "The effect of Indian Ocean warming on the Indian Monsoon: An atmospheric model study." MAUSAM 52, no. 1 (December 29, 2021): 151–62. http://dx.doi.org/10.54302/mausam.v52i1.1684.
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The results from an atmospheric modeling study using the Florida State University Global Spectral Model indicate that, in years such as 1997 when the Indian Ocean SSTs are large, the Indian monsoon exhibits a typical behaviour. During that year, an extended shift of the tropical convergence zone towards the north played a role in the regional Hadley cell anomalies. The local warm boundary conditions in the northwestern Indian Ocean aided the high rainfall anomaly in Western India during the model simulations. The upper level structure, exhibited in terms of the global velocity potential is slightly shifted east for 1997, but with the correct sign. This structure shows regions of convergence over Indonesia where severe drought had occurred. The performance of the model rainfall over the equatorial Indian Ocean was uncanny for most seasons studied. Overall, the model performed best over the oceanic regions.
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Krishnamurti, T. N., A. Thomas, Anu Simon, and Vinay Kumar. "Desert Air Incursions, an Overlooked Aspect, for the Dry Spells of the Indian Summer Monsoon." Journal of the Atmospheric Sciences 67, no. 10 (October 1, 2010): 3423–41. http://dx.doi.org/10.1175/2010jas3440.1.
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Abstract The year 2009 was a major drought year for the Indian summer monsoon with a seasonal deficit of rainfall by 21.6%. Standard oceanic predictors such as ENSO and the Indian Ocean dipole are not consistent for these dry spells. There are a host of other parameters such as the Himalayan ice cover, the Eurasian snow cover, the passage of intraseasonal waves, and even accumulated effects of Asian pollution that have been considered for analysis of the dry spells of the monsoon. This paper presents another factor, the western Asian desert air incursions toward central India, and emphasizes the formation of a blocking high over western Asia as an important feature for these dry spells. The blocking high advects descending very dry air toward central India, portrayed using swaths of three-dimensional trajectories. This is a robust indicator for dry spells of the monsoon during the last several decades. This dry air above the 3-km level over central India strongly inhibits the vertical growth of deep convection. Some of the interesting antecedents of the formation of the blocking high include an eastward and somewhat northward extension of the ITCZ over North Africa, a stronger than normal local Hadley cell over North Africa, a strong subtropical jet stream over the southern Mediterranean, and strong conversions of anticyclonic shear vorticity to anticyclonic curvature vorticity. The dynamical antecedents of the aforementioned scenario in this study are related to many aspects of North African weather features. They are portrayed using both reanalysis datasets and ensemble modeling using a suite of coupled atmosphere–ocean models.
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Chen, Jiepeng, Jin-Yi Yu, Xin Wang, and Tao Lian. "Different Influences of Southeastern Indian Ocean and Western Indian Ocean SST Anomalies on Eastern China Rainfall during the Decaying Summer of the 2015/16 Extreme El Niño." Journal of Climate 33, no. 13 (July 1, 2020): 5427–43. http://dx.doi.org/10.1175/jcli-d-19-0777.1.
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ABSTRACTPrevious studies linked the increase of the middle and low reaches of the Yangtze River (MLRYR) rainfall to tropical Indian Ocean warming during extreme El Niños’ (e.g., 1982/83 and 1997/98 extreme El Niños) decaying summer. This study finds the linkage to be different for the recent 2015/16 extreme El Niño’s decaying summer, during which the above-normal rainfalls over MLRYR and northern China are respectively linked to southeastern Indian Ocean warming and western tropical Indian Ocean cooling in sea surface temperatures (SSTs). The southeastern Indian Ocean warming helps to maintain the El Niño–induced anomalous lower-level anticyclone over the western North Pacific Ocean and southern China, which enhances moisture transport to increase rainfall over MLRYR. The western tropical Indian Ocean cooling first enhances the rainfall over central-northern India through a regional atmospheric circulation, the latent heating of which further excites a midlatitude Asian teleconnection pattern (part of circumglobal teleconnection) that results in an above-normal rainfall over northern China. The western tropical Indian Ocean cooling during the 2015/16 extreme El Niño is contributed by the increased upward latent heat flux anomalies associated with enhanced surface wind speeds, opposite to the earlier two extreme El Niños.
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RAJEEVAN, M., R. K. PRASAD, and U. S. DE. "Cloud climatology of the Indian Ocean based on ship observations." MAUSAM 52, no. 3 (January 11, 2022): 527–40. http://dx.doi.org/10.54302/mausam.v52i3.1722.
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Surface cloud data based on synoptic observations made by Voluntary Observing Ships (VOS) during the period 1951-98 were used to prepare the seasonal and annual cloud climatology of the Indian Ocean. The analysis has been carried out by separating the long-term trends, decadal and inter-annual components from the monthly cloud anomaly time series at each 5° × 5° grids.
Maximum zone of total and low cloud cover shifts from equator to northern parts of India during the monsoon season. During the monsoon season (June-September), maximum total cloud cover exceeding 70% and low cloud cover exceeding 50% are observed over north Bay of Bengal. Maximum standard deviation of total and low cloud cover is observed near the equator and in the southern hemisphere. Both total and low cloud cover over Arabian Sea and the equatorial Indian Ocean are observed to decrease during the ENSO events. However, cloud cover over Bay of Bengal is not modulated by the ENSO events. On inter-decadal scale, low cloud cover shifted from a "low regime" to a "high regime" after 1980 which may be associated with the corresponding inter-decadal changes of sea surface temperatures over north Indian Ocean observed during the late 1970s.
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SlNGH, J. P., and D. S. PAI. "An oceanic model for the prediction of southwest monsoon rainfall over India." MAUSAM 47, no. 1 (December 14, 2021): 91–98. http://dx.doi.org/10.54302/mausam.v47i1.3694.
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Nine new oceanic predictor for long range forecasting of Indian summer monsoon rainfall been identified utilizing the marine meteorological data of the North Indian Ocean and the monsoon rainfall data of the period 1961-91. In order to develop a reliable regression model the principal component analysis (PCA) of original variables has been done. Five parameters having maximum influence on first principal component, which is having highest correlation with the monsoon rainfall are : wind power in the atmospheric boundary layer over the north Indian Ocean between Equator and 100 N, mean evaporation over the Arabian Sea (00 -150 N) mean sea surface temperature (SST) gradient over the Arabian Sea between 7.50 – 17.50 N, mean evaporation over Bay of Bengal between Equator and 100 N and mean sea level pressure (SLP) over the Arabian Sea, each pertaining to the month of May. A multiple regression model for all Indian rainfall of southwest monsoon season has been developed using the principal components which have got good cor-relations with the monsoon rainfall. The model was tested for all the years from 1987 to 1991 and it has been found that the predicted values of all India summer monsoon rainfall of all the years except 1989 were very close to the actual values. However, there was a substantial difference between the predicted and actual rainfall of 1989 summer monsoon.
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Yadav, Ramesh Kumar, and Mathew Koll Roxy. "On the relationship between north India summer monsoon rainfall and east equatorial Indian Ocean warming." Global and Planetary Change 179 (August 2019): 23–32. http://dx.doi.org/10.1016/j.gloplacha.2019.05.001.
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Andrej Dávid, Andrea Galieriková, Jiří Tengler, and Vlatka Stupalo. "The Northern Sea Route as a New Route for Maritime Transport between the Far East and Europe." Communications - Scientific letters of the University of Zilina 23, no. 2 (April 1, 2021): A74—A79. http://dx.doi.org/10.26552/com.c.2021.2.a74-a79.
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Asian countries such as China, Malaysia, India or Bangladesh belong to the largest producers of consumer goods in the world that is mainly transported by container vessels to other parts of the world. One of the busiest maritime trade route is the route between Europe and Asia. It leads through the North Pacific, Indian and the North Atlantic Oceans and their seas. There is also an alternative trade route that runs along the coast of the Russian Federation across the Arctic Ocean. On one hand the ice in this area is gradually declining due to global warming, on the other hand the duration of navigation times is being extended for several months of the year. One of the advantages of this route is the reduction of sailing times between Asian and European maritime ports. The basic goals of the paper are to focus on the current transport situation on this trade route and a new trade route that leads along the coast of Russia.
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SCRIPTER, MATTHEW J., W. WAYNE PRICE, and RICHARD W. HEARD. "Redescription of Deltamysis holmquistae Bowman & Orsi, 1992 (Crustacea: Mysida: Mysidae), a mysid species new to the Atlantic Ocean with observations on the taxonomic status of Kochimysis Panampunnayil & Biju, 2007." Zootaxa 4729, no. 4 (January 31, 2020): 501–18. http://dx.doi.org/10.11646/zootaxa.4729.4.3.
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The first occurrences of the estuarine mysid Deltamysis holmquistae Bowman & Orsi from the Atlantic Ocean are documented from sites on the eastern Florida and northwest Gulf of Mexico (Texas) coasts of North America. Based on examination of type material and specimens from Florida and Texas, considerable morphological variability and additional characters were observed necessitating a rediagnosis of the monotypic genus Deltamysis and a redescription of D. holmquistae. As a result of these new taxonomic criteria, the Indian Ocean species, Kochimysis pillaii Panampunnayil & Biju, described from southwest coastal India, is subsumed as a junior synonym of D. holmquistae. The current distribution of this apparently invasive species is probably due to maritime commerce. The geographical location of the endemic or source populations of D. holmquistae remains undetermined; however, its co-occurrence in California with three introduced Asian mysids suggests a northern Indian Ocean or northwest Pacific origin.
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GHANEKAR, S. P., S. G. NARKHEDKAR, and D. R. SIKKA. "Progress of Indian summer monsoon onset and convective episodes over Indo-Pacific region observed during 2009-2014." MAUSAM 67, no. 4 (December 8, 2021): 803–28. http://dx.doi.org/10.54302/mausam.v67i4.1409.
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Summer monsoon onset progress from the oceanic region of Southeast Bay of Bengal / Andaman Sea (Oceanr) up to extreme southwestern part of India (Kerala) for the years 2009 to 2014 is investigated. Synoptic weather information, INSAT/KALPANA-1 as well as cloud imageries archived from Dundee Satellite Receiving Station for May and early June for these years are used in the analysis. Upper-air reanalyzed winds from NCEP/NCAR and OLR data archived through NOAA satellites are also used. During the study period, the dates of monsoon onset as well as the time required for the advancement of onset from Oceanr to Kerala have shown a large variation. An attempt is made to investigate the causes for such variations. The results indicate that intense disturbances which formed over north Indian Ocean in 2009, 2010, 2013 and 2014 and over west-north Pacific Oceanic region in 2011 and 2012 have contributed for the same. Analysis is carried out, limiting its focus to bring out the role of these convective events in the observed variation of onset timing and its progress by taking case to case review of these events and bringing out their influence through synoptic analysis. Utility of this information in prediction of the progress of Indian summer monsoon onset is also brought out.
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RAY, T. K. "Sea surface temperature and southwest monsoon over India." MAUSAM 42, no. 1 (February 28, 2022): 71–76. http://dx.doi.org/10.54302/mausam.v42i1.2848.
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Importance of sea surface temperature (SST) over the Arabian Sea, Bay of Bengal and the north Indian Ocean is studied in relation with the formation and m1intenan';e of the southwest monsoon over India. SST over southeast Arabian Sea close to the west coast of India becomes maximum before the onset of monsoon over Kerala. Crossing of the equator by southern hemispheric warm water seems to be related with the early or late onset of the monsoon. Magnitude of the difference between SST and air temperature during pre-onset weeks gives valuable hints for early/late and excess/deficient monsoon. A large warm winter mass up to the depth of 100 metres shifts towards the west coast of India before the onset of the monsoon. In 1979, back and forth movement of this water mass seems to be related with the different phases of the monsoon over India.
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Mohapatra, M., B. K. Bandyopadhyay, and D. P. Nayak. "Evaluation of operational tropical cyclone intensity forecasts over north Indian Ocean issued by India Meteorological Department." Natural Hazards 68, no. 2 (March 14, 2013): 433–51. http://dx.doi.org/10.1007/s11069-013-0624-z.
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MOHAPATRA, M., D. P. NAYAK, R. P. SHARMA, and B. K. BANDYOPADHYAY. "Evaluation of official tropical cyclone track forecast over north Indian Ocean issued by India Meteorological Department." Journal of Earth System Science 122, no. 3 (June 2013): 589–601. http://dx.doi.org/10.1007/s12040-013-0291-1.
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BALAKRISHNAN, T. K., A. K. JASWAL, S. S. SINGH, and H. N. SRIVASTAVA. "Principal component analysis of monthly mean Area surface temperature over the Arabian Sea, Bay of Bengal and north Indian Ocean for two Contrasting sets of monsoon years." MAUSAM 44, no. 1 (December 31, 2021): 69–76. http://dx.doi.org/10.54302/mausam.v44i1.3778.
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The spatial distribution and temporal variation of the monthly mean SSTA over the Arabian Sea, Bay of Bengal and the north Indian Ocean were investigated for a set of contrasting years of monsoon over the period 1961-80 for months April through July using Empirical Orthogonal Function (EOF) technique with a view to identify regions that are significantly related to the monsoon rainfall. Over 75% of the total variance is, explained by the first mode EOF. SSTA over the north and northeast Arabian Sea during pre-monsoon months were found to be possible indicators of the ensuing monsoon activity. The higher eigen vectors in May over northeast Arabian Sea may signal good monsoon and vice versa. In June there is a marked contrast in the distribution of SST over the Arabian Sea between the two sets of the years the eastern Arabian Sea IS warmer for the deficient monsoon years while the entire Arabian Sea except over the extreme north Arabian Sea is cool during good monsoon years. There is formation of SSTA over the equatorial Indian Ocean area close to Indonesian island commencing from May which is more marked in June and is positively correlated with seasonal rainfall activity over India.
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Prasanna, V., and H. Annamalai. "Moist Dynamics of Extended Monsoon Breaks over South Asia." Journal of Climate 25, no. 11 (June 2012): 3810–31. http://dx.doi.org/10.1175/jcli-d-11-00459.1.
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In the present research to identify moist processes that initiate and maintain extended monsoon breaks over South Asia moisture and moist static energy (MSE) budgets are performed on the newly available European Centre for Medium-Range Weather Forecasts Interim reanalysis (ERA-Interim) and ensemble integrations from a coupled model. The hypothesis that interaction between moist physics and regional circulation and the role of cloud–radiation feedbacks are important is tested. Budget diagnostics show that dry advection is the principal moist process to initiate extended breaks. Its sources are (i) regional anticyclonic circulation anomalies forced by equatorial Indian Ocean negative rainfall anomalies advect low MSE air from north to central India, and (ii) rainfall enhancement over tropical west Pacific forces cyclonic circulation anomalies to its northwest as a Rossby wave response, and the northerlies at the poleward flank of this circulation advect air of low MSE content from north. The dominance of anomalous wind acting on climatological moisture gradient is confirmed from an examination of the moisture advection equation. A partition of various flux terms indicates that over central India, due to an increase in upwelling shortwave and longwave fluxes, radiative cooling increases during extended breaks. Here, enhanced rainfall over the equatorial Indian Ocean promotes anomalous radiative warming due to trapping of upwelling fluxes. The differential radiative heating anchors a local Hadley circulation with descent over central India. A direct implication of this research is that observational efforts are necessary to monitor the three-dimensional moisture distribution and cloud–radiation interaction over the monsoon region that would aid in better understanding, modeling, and predicting extended monsoon breaks.
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Majumder, Amit. "An Empirical Study on Socio-Economic Conditions of Fishermen of North-East Coastal Region of India." IRA-International Journal of Management & Social Sciences (ISSN 2455-2267) 11, no. 2 (May 22, 2018): 69. http://dx.doi.org/10.21013/jmss.v11.n2.p2.
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<p>Fishing is recognised as a source of food since the Stone Age. A fisherman is the one who is involved in the process of capturing fish and other species from a water body for living and earning purposes, which started with an objective of survival and transformed into a source of business. According to the Food and Agriculture Organisation (FAO) of the United Nations, fish output in India doubled between 1990 and 2010. India acquires 8129 kilometres of marine coastline involving over 1.5 million people who are directly or indirectly related to fishing industry. Being a natural consumable resource it contributes to food security of India, fish is considered as a consumable source and an income source simultaneously. Traditionally, there exist primarily two forms of fishing-Inland Fishing and Marine Fishing. While the former is preferable to the local customers in India due to variety of tastes, on the other hand the Marine Fishing is considered as one of the significant foreign exchange earners as well as suppliers of huge nutritional requirements for this vast population. Nearly 60 per cent of Indian fish productions are coming from coastal fishing. To step up deep-sea fishing activities, in 1977 the Government extended its territorial control over 200 nautical miles in the ocean. This zone was termed as ‘Exclusive Economic Zone’ (EEZ). About 6.3% of global fish production as well as 1.1% of Indian GDP and 5.15% of agricultural GDP is contributed by Indian fishing industry.</p>
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Heidarzadeh, Mohammad, Alexander Rabinovich, Satoshi Kusumoto, and C. P. Rajendran. "Field surveys and numerical modelling of the 2004 December 26 Indian Ocean tsunami in the area of Mumbai, west coast of India." Geophysical Journal International 222, no. 3 (June 4, 2020): 1952–64. http://dx.doi.org/10.1093/gji/ggaa277.
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ABSTRACT In the aftermath of the 2004 Indian Ocean (Sumatra-Andaman) tsunami, numerous survey teams investigated its effects on various locations across the Indian Ocean. However, these efforts were focused only on sites that experienced major destruction and a high death toll. As a consequence, some Indian Ocean coastal megacities were not examined. Among the cities not surveyed was Mumbai, the principal west coast port and economical capital of India with a population of more than 12 million. Mumbai is at risk of tsunamis from two major subduction zones in the Indian Ocean: the Sumatra–Andaman subduction zone (SASZ) and the Makran subduction zone (MSZ). As a part of the present study, we conducted a field survey of the 2004 Indian Ocean tsunami effects in Mumbai, analysed the available tide gauge records and performed tsunami simulations. Our field survey in 2018 January found run-up heights of 1.6−3.3 m in the Mumbai area. According to our analysis of tide gauge data, tsunami trough-to-crest heights in Okha (550 km to the north of Mumbai) and in Mormugao (410 km to the south of Mumbai) were 46 cm and 108 cm, respectively. Simulations of a hypothetical MSZ Mw 9.0 earthquake and tsunami, together with the Mw 9.1 Sumatra–Andaman earthquake and tsunami, show that the tsunami heights generated in Mumbai by an MSZ tsunami would be significantly larger than those generated by the 2004 Sumatra–Andaman tsunami. This result indicates that future tsunami hazard mitigation for Mumbai needs to be based on a potential large MSZ earthquake rather than an SASZ earthquake.
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Bhattacharya, Bhaswati. "A Note on the Shipbuilding in Bengal in the Late Eighteenth Century." Itinerario 19, no. 3 (November 1995): 167–74. http://dx.doi.org/10.1017/s0165115300021380.
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Both overseas trade and shipbuilding in India are of great antiquity. But even for the early modern period, maritime commerce is relatively better documented than the shipbuilding industry. When the Portuguese and later the North Europeans entered the intra-Asian trade, many of the ships they employed in order to supplement their shipping in Asia were obtained from the Indian dockyards. Detailed evidence with regard to shipbuilding, however, is very rare. It has been pointed out that the Portuguese in the sixteenth century were more particular than their North-European counter-parts in the following centuries in providing information on seafaring and shipbuilding. Shipbuilding on the west coast has been discussed more than that on the eastern coast of India, particularly the coast of Bengal. Though Bengal had a long tradition of shipbuilding, direct evidence of shipbuilding in the region is rare. Many changes were brought about in the history of India and the Indian Ocean trade of the eighteenth century, especially after the 1750s. When the English became the largest carriers of Bengal's trade with other parts of Asia, this had an impact on the shipbuilding in Bengal. It was in their interest that the British in Bengal had their ships built in that province.
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Desai, Gaurav. "Oceans Connect: The Indian Ocean and African Identities." PMLA/Publications of the Modern Language Association of America 125, no. 3 (May 2010): 713–20. http://dx.doi.org/10.1632/pmla.2010.125.3.713.
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Readers of PMLA Recognize 26 Broadway, in New York City, as the Headquarters of the Mla, One of the Major Hubs of Intellectual work in literary and cultural studies in North America. But in the summer of 1840, 26 Broadway was a commercial hub that connected the world of the Atlantic Ocean with the world of the Indian Ocean. Here, in the offices of the New York firm Barclay and Livingston, Ahmad Bin Na'aman, special envoy of the sultan of Zanzibar, Sayyid Said, offered for sale merchandise that had been brought to the United States from Muscat and Zanzibar. The merchandise included “1,300 bags of dates, 21 bales of Persian wool carpets and 100 bales of Mokha coffee” that had been acquired at Muscat and “108 prime ivory tusks, 81 cases of gum copal, … 135 bags of cloves and 1,000 dry salted hides” from Zanzibar (Eilts 32). The cargo had come to New York on 30 April 1840 aboard the Sultanah, a bark owned by the sultan and commanded by William Sleeman, an Englishman. Except for two Frenchmen whose identities are uncertain and two Englishwomen who had sought passage to London, where the ship was headed, most of those on board were African slaves belonging to the ship's officers and hired lascars, Muslim seamen from the lower Konkan and Malabar coasts of India who had been signed on in Bombay, where the ship had been refitted for the transatlantic voyage and from which it first embarked (3). The slaves, we are told, were dressed in garments made of coarse cotton cloth “called merikani, after the country of its manufacture” (4). In his account of the voyage of the Sultanah, Hermann Frederick Eilts writes of “the pungent vapors of cloves, gum copal and coffee (from the ship's cargo), of tar and pitch, of open-hearth cooking in deep, acrid sheep tail's fat, called ghee, of primitive shipboard sanitation and of coconut oil” (4). This account of the “first Arab emissary and the first Arab vessel to visit American shores” is a rich reminder of the historical interconnections in the world (6).
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Bahl, Christopher D. "Transoceanic Arabic historiography: sharing the past of the sixteenth-century western Indian Ocean." Journal of Global History 15, no. 2 (June 25, 2020): 203–23. http://dx.doi.org/10.1017/s1740022820000017.
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AbstractThe early modern western Indian Ocean constituted a dynamic space of human interaction. While scholarship has mostly concentrated on trade and commerce, recent studies have shifted the focus to social and cultural mobilities. This article argues for the emergence of a transoceanic Arabic historiography during the sixteenth century, which reflected on the cultural integration of regions from Egypt, the Hijaz, and Yemen in the Red Sea region, to Gujarat, the Deccan, and Malabar in the subcontinent. Historians from the Persian cosmopolis further north observed a strong cultural connection between Arabophone communities of the western Indian Ocean region. Manuscript collections in India show that Arabic historical texts from the Red Sea region had a readership in the subcontinent. Most importantly, mobile scholars began to compose Arabic histories while receiving patronage at the western Indian courts. Scholarly mobilities fostered cultural exchanges, which increasingly built on a shared history, written, read, and circulated in Arabic during the sixteenth century
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Norman, M., C. Leck, and H. Rodhe. "Interhemispheric differences in the chemical characteristics of the Indian Ocean aerosol during INDOEX." Atmospheric Chemistry and Physics Discussions 2, no. 6 (December 16, 2002): 2373–411. http://dx.doi.org/10.5194/acpd-2-2373-2002.
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Abstract. The water soluble inorganic part of the sub-micrometer aerosol was measured from two research vessels over the Indian Ocean during the winter monsoon season (February and March) as part of the INDOEX project in 1998 and 1999. Additional measurements were made of gas phase SO2 from one of the vessels in 1999. All samples collected north of the ITCZ were clearly affected by continental, anthropogenic sources. A sharp transition occurred across the ITCZ with concentrations of nss-SO42, NH4+ and nss-K+ being lower by a factor of 7--15, >20 and >40, respectively, on the southern side of the ITCZ. The contribution from DMS to the sub-micrometer nss-SO42 was estimated to be up to 40% in clean air north of the ITCZ but less than 10% in polluted air originating from India. South of the ITCZ virtually all nss-SO42 was likely to be derived from oxidation of DMS. The concentration of \\chem{SO_2} decreased rapidly with distance from the Indian coast, the ratio \\SO2nss-SO42 reaching values below 5% after 35 h travel time over the ocean. Surprisingly, MSA, which is derived from DMS, also showed higher concentrations in the sub-micrometer aerosol north of the ITCZ than south of it. This could be explained by the larger sub-micrometer surface area available north of the ITCZ for the condensation of MSA. South of the ITCZ a major part of the MSA was found on the super-micrometer particles. The total amount of MSA, on both sub-micrometer and super-micrometer particles, varied little across the ITCZ. An analysis based on the air trajectories showed that systematic variation in the observed concentrations was associated with variations in the transport from source regions. For example, differences in time since air parcels left the Arabian or Indian coasts was shown to be an important factor for explaining the substantial differences in absolute concentrations.
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Pattanaik, D. R. "Variability of Convective Activity over the North Indian Ocean and its Associations with Monsoon Rainfall over India." Pure and Applied Geophysics 164, no. 8-9 (June 29, 2007): 1527–45. http://dx.doi.org/10.1007/s00024-007-0243-2.
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MOHAMMEDNOWSHAD, B., K. K. IDREESBABU, USHA V. PARAMESWARAN, CHARLES G. MESSING, and S. SURESHKUMAR. "The Shallow-water Crinoid Fauna of Lakshadweep Atolls, North-western Indian Ocean." Zootaxa 4789, no. 1 (June 8, 2020): 247–65. http://dx.doi.org/10.11646/zootaxa.4789.1.9.
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A biodiversity survey carried out from 2016 to 2018 by the Department of Science and Technology in the Lakshadweep Atolls, India, recorded six species of shallow-water feather stars new to the archipelago (Comanthus wahlbergii, Comaster schlegelii, Himerometra robustipinna, Dichrometra palmata, Stephanometra indica, and Phanogenia typica). Himerometra sol A.H. Clark, 1912, previously known only from the Maldive Islands, is synonymized under Himerometra robustipinna (Carpenter, 1881). This study brings the total number of shallow-water crinoids recorded from Lakshadweep to ten species. Of the four species collected previously from the archipelago, only Comatella nigra was found in this survey. Of those not collected, Comatella stelligera and Oligometra serripinna are widespread in the Indo-western Pacific region, whereas Heterometra compta is known only from Lakshadweep, and its validity remains uncertain. The known shallow-water crinoid fauna of the archipelago is substantially less diverse than that of the adjacent and environmentally similar Maldive Islands, emphasizing the need for additional research in this island group, in particular, to determine whether the differences are actual or not, and whether they are based on natural conditions versus anthropogenic impacts.
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Mehra, P., S. Mohan, P. Vethamony, K. Vijaykumar, T. M. Balakrishnan Nair, Y. Agarvadekar, K. Jyoti, et al. "Coastal sea level response to the tropical cyclonic forcing in the north Indian Ocean." Ocean Science Discussions 11, no. 1 (February 20, 2014): 575–611. http://dx.doi.org/10.5194/osd-11-575-2014.
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Abstract. The study examines the observed storm-generated sea-level variation due to deep depression (Event-E1) in the Arabian Sea from 26 November–1 December 2011 and a cyclonic storm "THANE" (Event-E2) over the Bay of Bengal during 25–31 December 2011. The sea-level and surface meteorological measurements collected during these extreme events exhibit strong synoptic disturbances leading to storm surge up to 43 cm on the west coast and 29 cm on the east coast of India due to E1 and E2. E1 generated sea level oscillations at the measuring stations on the west coast (Ratnagiri, Verem and Karwar) and east coast (Mandapam and Tuticorin) of India with significant energy bands centered at periods of 92, 43 and 23 min. The surge dome has a duration of 92.6, 84.5 and 74.8 h at Ratnagiri, Verem and Karwar, respectively. However, on the east coast, the sea level oscillations during Thane were similar to those during calm period except for more energy bands centred at periods of ~ 100, 42 and 24 min at Gopalpur, Gangavarm and Kakinada, respectively. Multi-linear regression analysis shows that the local surface meteorological data (daily-mean wind and atmospheric pressure) is able to account for ~ 57% and ~ 70% of daily-mean sea-level variability along the east and west coast of India. The remaining part of variability observed in the sea level may be attributed to local coastal currents and remote forcing.
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Choudhury, Pankaj. "REVERBERATION OF PANDEMIC MIGRANT FOOTPRINTS AND POLICY MANIFESTATION: A PROGRESSIVE STATE APPROACH OF NORTH-EAST INDIA." Journal of Law and Policy Transformation 7, no. 2 (January 1, 2023): 138–51. http://dx.doi.org/10.37253/jlpt.v7i2.7371.
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This is the defining moment of our generation. We are facing a global health crisis, one that is killing people, spreading human suffering, and upending people’s lives. The Covid-19 pandemic and sudden global lockdown across nations has brought migrant livelihoods to a halt. The headlines around Covid-19 are enough to scare us witless. The migrant crisis brought to the fore the unfulfilled obligations of the governments to restore work to its most vulnerable citizens in the era of economic liberalization. The migration debate has become central to political circle which largely involves rehearsing to false dichotomies whereas migrants are in continuous drift. Debate is just not restricted to utility of limited public funds. We have to create an ‘island of opportunities’ in this ‘ocean of distress’. The research poses the questions, namely: 1. How did immigration occur in North-east India? 2) How were the debates relating to migrants from North-east India? 3) How did the government of North-east India respond to the situation of migrants from North-east India during the Covid-19 pandemic? It was found and concluded that growing rural distress with agricultural failing leading to heavy debt burdens was the primary reason of immigration in North-east India. “The Assam Accord” signed between the “Government of India” and the “Leaders of the Assam Movement” in 1985 effectively legitimized all immigrants entering Assam before 24, December 1971. The SHG’s under National Rural Livelihoods Mission (NRLM) and Assam State Rural Livelihoods Mission (ASRLM) had adopted series of remedial measures during the Covid-19 pandemic for people, including migrants from North-east India.
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Norman, M., C. Leck, and H. Rodhe. "Differences across the ITCZ in the chemical characteristics of the Indian Ocean MBL aerosol during INDOEX." Atmospheric Chemistry and Physics 3, no. 3 (May 28, 2003): 563–79. http://dx.doi.org/10.5194/acp-3-563-2003.
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Abstract. The water soluble inorganic part of the sub-micrometer aerosol was measured from two research vessels over the Indian Ocean during the winter monsoon season (February and March) as part of the INDOEX project in 1998 and 1999. Additional measurements were made of gas phase SO2 from one of the vessels in 1999. All samples collected north of the Inter Tropical Convergence Zone, ITCZ, were clearly affected by continental, anthropogenic sources. A sharp transition occurred across the ITCZ with concentrations of nss-SO42-, NH4+ and nss-K+ being lower by a factor of 7-15, >20 and >40, respectively, on the southern side of the ITCZ. The contribution from DMS to the sub-micrometer nss-SO42- was estimated to be up to 40% in clean air north of the ITCZ but less than 10% in polluted air originating from India. South of the ITCZ virtually all nss-SO42- was likely to be derived from oxidation of DMS. The concentration of SO2 decreased rapidly with distance from the Indian coast, the molar ratio SO2/nss-SO42- reaching values below 5% after 35 h travel time over the ocean. Surprisingly, MSA, which is derived from DMS, also showed higher concentrations in the sub-micrometer aerosol north of the ITCZ than south of it. This could be explained by the larger sub-micrometer surface area available north of the ITCZ for the condensation of MSA. South of the ITCZ a major part of the MSA was found on the super-micrometer particles. An analysis based on the air trajectories showed that systematic variation in the observed concentrations was associated with variations in the transport from source regions. For example, differences in time since air parcels left the Arabian or Indian coasts was shown to be an important factor for explaining the substantial differences in absolute concentrations.
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Sato, Tomonori, and Fujio Kimura. "How Does the Tibetan Plateau Affect the Transition of Indian Monsoon Rainfall?" Monthly Weather Review 135, no. 5 (May 1, 2007): 2006–15. http://dx.doi.org/10.1175/mwr3386.1.
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Abstract The roles of the Tibetan Plateau (TP) upon the transition of precipitation in the south Asian summer monsoon are investigated using a simplified regional climate model. Before the onset of the south Asian monsoon, descending flow in the midtroposphere, which can be considered as a suppressor against precipitation, prevails over northern India as revealed by the NCEP–NCAR reanalysis data. The descending motion gradually weakens and retreats from this region before July, consistent with the northwestward migration of the monsoon rainfall. To examine a hypothesis that the dynamical and thermal effects of TP cause the midtropospheric subsidence and its seasonal variation, a series of numerical experiments are conducted using a simplified regional climate model. The mechanical effect of the TP generates robust descending flow over northern India during winter and spring when the zonal westerly flow is relatively strong, but the effect becomes weaker after April as the westerly flow tends to be weaker. The thermal effect of the TP, contrastingly, enhances the descending flow over north India in the premonsoonal season. The descending flow enhanced by the thermal effect of the TP has a seasonal cycle because the global-scale upper-level westerly changes the energy propagation of the thermal forcing response. The subsidence formed by the mechanical and thermal effects of the TP disappears over northern India after the subtropical westerly shifts north of the plateau, the seasonal change of which is in good agreement with that in the reanalysis data. The retreat of the descending flow can be regarded as the withdrawal of the premonsoon season and the commencement of the south Asian monsoon. After that, the deep convection, indicating the onset of the Indian summer monsoon, is able to develop over north India in relation to the ocean–atmosphere and land–atmosphere interaction processes. Northwest India is known to be the latest region of summer monsoon onset in south Asia. Thus, the thermal and mechanical forcing of the TP has great impact on the transition of the Indian monsoon rainfall by changing the midtropospheric circulation.
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Chowdary, J. S., Anant Parekh, G. Srinivas, C. Gnanaseelan, T. S. Fousiya, Rashmi Khandekar, and M. K. Roxy. "Processes Associated with the Tropical Indian Ocean Subsurface Temperature Bias in a Coupled Model." Journal of Physical Oceanography 46, no. 9 (September 2016): 2863–75. http://dx.doi.org/10.1175/jpo-d-15-0245.1.
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AbstractSubsurface temperature biases in coupled models can seriously impair their capability in generating skillful seasonal forecasts. The National Centers for Environmental Prediction (NCEP) Climate Forecast System, version 2 (CFSv2), coupled model, which is used for seasonal forecast in several countries including India, displays warm (cold) subsurface (surface) temperature bias in the tropical Indian Ocean (TIO), with deeper than observed mixed layer and thermocline. In the model, the maximum warm bias is reported between 150- and 200-m depth. Detailed analysis reveals that the enhanced vertical mixing by strong vertical shear of horizontal currents is primarily responsible for TIO subsurface warming. Weak upper-ocean stability corroborated by surface cold and subsurface warm bias further strengthens the subsurface warm bias in the model. Excess inflow of warm subsurface water from Indonesian Throughflow to the TIO region is partially contributing to the warm bias mainly over the southern TIO region. Over the north Indian Ocean, Ekman convergence and downwelling due to wind stress bias deepen the thermocline, which do favor subsurface warming. Further, upper-ocean meridional and zonal cells are deeper in CFSv2 compared to the Ocean Reanalysis System data manifesting the deeper mixing. This study outlines the need for accurate representation of vertical structure in horizontal currents and associated vertical gradients to simulate subsurface temperatures for skillful seasonal forecasts.
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Andersen, R. Charles, Trevor A. Branch, Anoma Alagiyawadu, Robert Baldwin, and Francis Marsac. "Seasonal distribution, movements and taxonomic status of blue whales (Balaenoptera musculus) in the northern Indian Ocean." J. Cetacean Res. Manage. 12, no. 2 (February 8, 2023): 203–18. http://dx.doi.org/10.47536/jcrm.v12i2.578.
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There is a distinct population of blue whales, Balaenoptera musculus, in the northern Indian Ocean. The taxonomic status of these animals has long been uncertain, with debate over whether this population represents a distinct subspecies, and if so which name should apply. They have most frequently been assigned to B. musculus brevicauda, but are currently considered to be B. m. indica. The movements of these blue whales within the northern Indian Ocean are poorly understood. This paper reviews catches (n = 1,288), sightings (n = 448, with a minimum of 783 animals), strandings (n = 64) and acoustic detections (n = 6 locations); uses ocean colour data to estimate seasonality of primary productivity in different areas of the northern Indian Ocean; and develops a migration hypothesis. It is suggested that most of these whales feed in the Arabian Sea off the coasts of Somalia and the Arabian peninsula during the period of intense upwelling associated with the southwest monsoon (from about May to October). At the same time some blue whales also feed in the area of upwelling off the southwest coast of India and west coast of Sri Lanka. When the southwest monsoon dies down in about October–November these upwellings cease. The blue whales then disperse more widely to eke out the leaner months of the northeast monsoon (during about December to March) in other localised areas with seasonally high productivity. These include the east coast of Sri Lanka, the waters west of the Maldives, the vicinity of the Indus Canyon (at least historically), and some parts of the southern Indian Ocean. The data are consistent with the hypothesis that at least some of the blue whales that feed off the east coast of Sri Lanka in the northeast monsoon also feed in the Arabian Sea during the southwest monsoon. These whales appear to migrate eastwards past the north of Maldives and south of Sri Lanka in about December–January, returning westwards in about April–May
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GUPTA, AKHILESH, and U. C. MOHANTY. "Secondary convective rings in an intense asymmetric cyclone of the Bay or Bengal." MAUSAM 48, no. 2 (December 15, 2021): 273–82. http://dx.doi.org/10.54302/mausam.v48i2.4010.
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ABSTRACT. The severe cyclonic storm with a core of hurricane winds of 4-11 May 1990, which crossed the Indian east coast near Machilipatnarn (Andhra Pradesh), was one of the most intense cyclones in recent years over the Bay of Bengal region of the north Indian Ocean. The storm reported the minimum sea level pressure of 912 hPa, the lowest observed value for any cyclone in the region. The storm exhibited certain interesting structural characteristics. The most striking feature observed was the formation of secondary convective rings wrapped around the primary eyewall. These features were observed for nearly two days by four cyclone detection radars (CDR) located on the east coast of India. The paper presents an analysis of these features. We find that the double eye-wall structure of the storm has undergone a repetitive cycle characterized by the contraction of the outer eyewall and the weakening of the inner eyewall during the life of the cyclone. These interesting characteristics are observed for the first time in the north Indian Ocean for any cyclone. Some of the related aspects of double eyewall features, such as, the possible role of double eyewall structure on the recurvature or turning of the storm and the effect of land obstacle in the development of a secondary eyewall are discussed.
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Anderson, Charles, Isha, Dipani Sutaria, and Asha De Vos. "note on humpback whales (Megaptera novaeangliae) in the central Indian Ocean." J. Cetacean Res. Manage. 23, no. 1 (July 20, 2022): 49–57. http://dx.doi.org/10.47536/jcrm.v23i1.341.
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In the central Indian Ocean, humpback whales (Megaptera novaeangliae) are rare. Records from southern India, Sri Lanka, Maldives and the Chagos Archipelago (n=67) were compiled and show a bimodal pattern of seasonal occurrence. Those occurring during the northern winter (December to April) are known to belong to the Arabian Sea humpback whale population. There have been no humpback whales recorded in Maldives during the northern winter since 2001, suggesting a possible range contraction for the Arabian Sea humpback whale population. Humpback whales occurring during the southern winter (June to October) are assumed to belong to the southwest Indian Ocean population (IWC breeding stock C). In this case, numbers of opportunistic sightings are increasing and the population appears to be spreading northwards as it recovers from commercial whaling, with several recent southern winter records from as far north as 5°N in northern Maldives and southern Sri Lanka. For this southern hemisphere population, calves are first seen in August, with numbers of calves increasing in September and October. For both populations, interactions with regional fisheries, particularly pelagic gillnetting, may be a major cause of mortality.
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Ma, Caihong, Zheng Niu, Yan Ma, Fu Chen, Jin Yang, and Jianbo Liu. "Assessing the Distribution of Heavy Industrial Heat Sources in India between 2012 and 2018." ISPRS International Journal of Geo-Information 8, no. 12 (December 10, 2019): 568. http://dx.doi.org/10.3390/ijgi8120568.
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The heavy industry in India has witnessed rapid development in the past decades. This has increased the pressures and load on the Indian environment, and has also had a great impact on the world economy. In this study, the Preparatory Project Visible Infrared Imaging Radiometer (NPP VIIRS) 375-m active fire product (VNP14IMG) and night-time light (NTL) data were used to study the spatiotemporal patterns of heavy industrial development in India. We employed an improved adaptive K-means algorithm to realize the spatial segmentation of long-term VNP14IMG data and artificial heat-source objects. Next, the initial heavy industry heat sources were distinguished from normal heat sources using a threshold recognition model. Finally, the maximum night-time light data were used to delineate the final heavy industry heat sources. The results suggest, that this modified method is a much more accurate and effective way of monitoring heavy industrial heat sources, and the accuracy of this detection model was higher than 92.7%. The number of main findings were concluded from the study: (1) the heavy industry heat sources are mainly concentrated in the north-east Assam state, east-central Jharkhand state, north Chhattisgarh and Odisha states, and the coastal areas of Gujarat and Maharashtra. Many heavy industrial heat sources were also found around a line from Kolkata on the Eastern Indian Ocean to Mumbai on the Western Indian Ocean. (2) The number of working heavy industry heat sources (NWH) and, particularly, the total number of fire hotspots for each working heavy industry heat source area (NFHWH) are continuing to increase in India. These trends mirror those for the Gross Domestic Product (GDP) and total population of India between 2012 and 2017. (3) The largest values of NWH and NFHWH were in Jharkhand, Chhattisgarh, and Odisha whereas the smallest negative values, the S l o p e _ N W H in Jharkhand and Chhattisgarh were also the two largest values in the whole country. The smallest negative values of S l o p e _ N W H and S l o p e _ N F H W H were in Haryana. The S l o p e _ N F H W H in the mainland Gujarat had the second most negative value, while the value of the S l o p e _ N W H was the third-highest positive value.