Source regions of oxygen maxima in intermediate depths of the Arabian Sea.

1966 ◽  
Vol 17 (1) ◽  
pp. 1 ◽  
Author(s):  
DJ Rochford
Keyword(s):  
Indian Ocean ◽  
Arabian Sea ◽  
Structural Features ◽  
The South ◽  
The North ◽  
Source Regions ◽  
South Indian ◽  
Indian Central ◽  
South West Monsoon ◽  
The Indian Ocean

Oxygen maxima, in relation to σt salinity maxima and minima, and other hydrological structural features, have been examined along three meridional sections of the Indian Ocean. These relations have provided a background for the interpretation of the water mass sources of oxygen maxima of the whole Indian Ocean. After grouping these oxygen maxima according to density, their salinities have been used to identify mixing circuits in which the following waters are involved: from the south (1) South Indian Central, (2) Subtropical oxygen maximum, (3) Antarctic Intermediate; from the east (4) Equatorial Frontal water; and from the north (5) Persian Gulf, and (6) Red Sea. The principal routes whereby oxygen-rich mixtures of these waters enter the Arabian Sea, during the south-west monsoon, have been determined. The directions of flow along several of these routes agreed with measured directions of current flow. Where these currents disagreed the measured current was generally very weak.

The phosphate levels of the major surface currents of the Indian Ocean

1967 ◽  
Vol 18 (1) ◽  
pp. 1 ◽  
Author(s):  
DJ Rochford
Keyword(s):  
Indian Ocean ◽  
High Salinity ◽  
Average Rate ◽  
North Indian Ocean ◽  
Surface Currents ◽  
The South ◽  
South Indian Ocean ◽  
The North ◽  
South Indian ◽  
South West Monsoon

The principal surface currents of the north Indian Ocean are much richer in phosphate (greater than 0.25 �g-atom/l) than those of the south Indian Ocean (less than 0.15 �g-atom/I). In summer large areas of the surface waters of the south-east Indian Ocean have a very low phosphate content (less than 0.10 �g-atom/l). These waters are by far the lowest in phosphate of the whole Indian Ocean. Their salinity-temperature- phosphate relations show that waters from two regions, the South Equatorial Current in the north and the high salinity belt around 30-35� S., contribute to their formation. Waters of this high salinity belt are carried northward into the low phosphate region by the West Australian Current in summer. These high-salinity waters most probably form by evaporation of an upper 50-m mixed layer of waters of the south-east Atlantic drifting eastward in the south Indian Ocean at an average rate of 15 cm per sec. In the eastern Indian Ocean north of 10�S., surface phosphate levels in summer are governed by the circulation of the richer phosphate waters of the counter current. In winter the circulation of richer phosphate waters of the South-west Monsoon Current governs the phosphate level.

Anthropogenic iron deposition alters the ecosystem and carbon balance of the Indian Ocean over a centennial timescale

2020 ◽  
Author(s):  
Anh Pham ◽  
Takamitsu Ito
Keyword(s):  
Indian Ocean ◽  
Arabian Sea ◽  
Ocean Basin ◽  
Ecosystem Dynamics ◽  
Carbon Uptake ◽  
The South ◽  
Nutrient Deposition ◽  
The North ◽  
The Indian Ocean ◽  
The Impact

<p>Phytoplankton growth in the Indian Ocean is generally limited by macronutrients (nitrogen: N and phosphorus: P) in the north and by micronutrient (iron: Fe) in the south. Increasing anthropogenic atmospheric deposition of N and dissolved Fe (dFe) into the ocean can thus lead to significant responses from marine ecosystems in this ocean basin. Previous modeling studies investigated the impacts of anthropogenic nutrient deposition on the ocean, but their results are uncertain due to incomplete representations of Fe cycling. We use a state-of-the-art ocean ecosystem and Fe cycling model to evaluate the transient responses of ocean productivity and carbon uptake in the Indian Ocean, focusing on the centennial time scale. The model incorporates all major external sources and represents a complicated internal cycling process of Fe, thus showing significant improvements in reproducing observations. Sensitivity simulations show that after a century of anthropogenic deposition, increased dFe stimulates diatoms productivity in the southern Indian Ocean poleward of 50⁰S and the southeastern tropics. Diatoms production weakens in the south of the Arabian Sea due to the P limitation, and diatoms are outcompeted there by coccolithophores and picoplankton, which have a lower P demand. These changes in diatoms and coccolithophores productions alter the balance between the organic and carbonate pumps in the Indian Ocean, increasing the carbon uptake in the south of 50⁰S and the southeastern tropics while decreasing it in the Arabian Sea. Our results reveal the important role of ecosystem dynamics in controlling the sensitivity of carbon fluxes in the Indian Ocean under the impact of anthropogenic nutrient deposition over a centennial timescale.</p>

scholarly journals Art. XXVII.—Notes on Malayalam Literature

1900 ◽  
Vol 32 (4) ◽  
pp. 763-768
Author(s):  
T. K. Krishṇa Menon
Keyword(s):  
Indian Ocean ◽  
Arabian Sea ◽  
The South ◽  
The West ◽  
The Third ◽  
The North ◽  
South West ◽  
The Indian Ocean

Malayalam is the language of the south-west of the Madras Presidency. It is the third most important language of the Presidency, the first and the second being Tamil and Telugu respectively. It is spoken in Malabar, Cochin, and Travancore. Out of a total of 5,932,207 inhabitants of these parts, 5,409,350 persons are those who speak Malayalam. These countries, taken as a whole, are bounded on the north, by South Canara, on the east by the far-famed Malaya range of mountains, on the south by the Indian Ocean, and on the west by the Arabian Sea.

scholarly journals The Geology of Portuguese Nyasaland

1922 ◽  
Vol 59 (5) ◽  
pp. 200-212
Author(s):  
Robert R. Walls
Keyword(s):  
Indian Ocean ◽  
East Africa ◽  
The South ◽  
The North ◽  
Dark Continent ◽  
The Indian Ocean

Portuguese Nyasaland is the name given to the most northern part of Portuguese East Africa, lying between Lake Nyasa and the Indian Ocean. It is separated from the Tanganyika territory in the north by the River Rovuma and from the Portuguese province of Mozambique in the south by the River Lurio. The territory measures about 400 miles from east to west and 200 miles from north to south and has an area of nearly 90,000 square miles. This territory is now perhaps the least known part of the once Dark Continent, but while the writer was actually engaged in the exploration of this country in 1920–1, the Naval Intelligence Division of the British Admiralty published two handbooks, the Manual of Portuguese East Africa and the Handbook of Portuguese Nyasaland, which with their extensive bibliographies contained practically everything that was known of that country up to that date (1920). These handbooks make it unnecessary in this paper to give detailed accounts of the work of previous explorers.

Art. VII.—Notes on Persian Belúchistán. From the Persian of Mirza Mehdy Khán. Published Teheran, July, 1875

1876 ◽  
Vol 9 (1) ◽  
pp. 147-154
Author(s):  
A. H. Schindler
Keyword(s):  
Indian Ocean ◽  
Temperate Climate ◽  
The South ◽  
The West ◽  
The North ◽  
The People ◽  
The Indian Ocean ◽  
The Hill ◽  
Cool Climate

The part of Belúchistán now under Persian rule is bounded upon the north by Seistán, upon the east by Panjgúr and Kej, upon the south by the Indian Ocean, and upon the west by Núrámshír, Rúdbár, and the Báshákerd mountains.This country enjoys a variety of climates; almost unbearable heat exists on the Mekrán coast, we find a temperate climate on the hill slopes and on the slightly raised plains as at Duzek and Bampúr, and a cool climate in the mountainous districts Serhad and Bazmán. The heat at Jálq is said to be so intense in summer that the gazelles lie down exhausted in the plains, and let themselves be taken by the people without any trouble.

Interannual Variability in Sea Surface Height at Southern Midlatitudes of the Indian Ocean

2021 ◽  
Vol 51 (5) ◽  
pp. 1595-1609
Author(s):  
Motoki Nagura ◽  
Michael J. McPhaden
Keyword(s):  
Indian Ocean ◽  
Interannual Variability ◽  
Sea Surface Height ◽  
Wind Forcing ◽  
Sea Surface ◽  
The South ◽  
South Indian Ocean ◽  
Eastern Boundary ◽  
South Indian ◽  
The Indian Ocean

AbstractThis study examines interannual variability in sea surface height (SSH) at southern midlatitudes of the Indian Ocean (10°–35°S). Our focus is on the relative role of local wind forcing and remote forcing from the equatorial Pacific Ocean. We use satellite altimetry measurements, an atmospheric reanalysis, and a one-dimensional wave model tuned to simulate observed SSH anomalies. The model solution is decomposed into the part driven by local winds and that driven by SSH variability radiated from the western coast of Australia. Results show that variability radiated from the Australian coast is larger in amplitude than variability driven by local winds in the central and eastern parts of the south Indian Ocean at midlatitudes (between 19° and 33°S), whereas the influence from eastern boundary forcing is confined to the eastern basin at lower latitudes (10° and 17°S). The relative importance of eastern boundary forcing at midlatitudes is due to the weakness of wind stress curl anomalies in the interior of the south Indian Ocean. Our analysis further suggests that SSH variability along the west coast of Australia originates from remote wind forcing in the tropical Pacific, as is pointed out by previous studies. The zonal gradient of SSH between the western and eastern parts of the south Indian Ocean is also mostly controlled by variability radiated from the Australian coast, indicating that interannual variability in meridional geostrophic transport is driven principally by Pacific winds.

Trend Analysis with a New Global Record of Tropical Cyclone Intensity

2013 ◽  
Vol 26 (24) ◽  
pp. 9960-9976 ◽  
Author(s):  
James P. Kossin ◽  
Timothy L. Olander ◽  
Kenneth R. Knapp
Keyword(s):  
Tropical Cyclone ◽  
Indian Ocean ◽  
Satellite Data ◽  
Formal Analysis ◽  
P Value ◽  
Tropical Cyclone Intensity ◽  
The South ◽  
Cyclone Intensity ◽  
The North ◽  
South Indian

Abstract The historical global “best track” records of tropical cyclones extend back to the mid-nineteenth century in some regions, but formal analysis of these records is encumbered by temporal heterogeneities in the data. This is particularly problematic when attempting to detect trends in tropical cyclone metrics that may be attributable to climate change. Here the authors apply a state-of-the-art automated algorithm to a globally homogenized satellite data record to create a more temporally consistent record of tropical cyclone intensity within the period 1982–2009, and utilize this record to investigate the robustness of trends found in the best-track data. In particular, the lifetime maximum intensity (LMI) achieved by each reported storm is calculated and the frequency distribution of LMI is tested for changes over this period. To address the unique issues in regions around the Indian Ocean, which result from a discontinuity introduced into the satellite data in 1998, a direct homogenization procedure is applied in which post-1998 data are degraded to pre-1998 standards. This additional homogenization step is found to measurably reduce LMI trends, but the global trends in the LMI of the strongest storms remain positive, with amplitudes of around +1 m s−1 decade−1 and p value = 0.1. Regional trends, in m s−1 decade−1, vary from −2 (p = 0.03) in the western North Pacific, +1.7 (p = 0.06) in the south Indian Ocean, +2.5 (p = 0.09) in the South Pacific, to +8 (p < 0.001) in the North Atlantic.

scholarly journals Microseisms associated with disturbed weather in the Indian seas

1930 ◽  
Vol 229 (670-680) ◽  
pp. 287-328 ◽  
Keyword(s):  
North Atlantic ◽  
Arabian Sea ◽  
The State ◽  
The South ◽  
Monsoon Period ◽  
The North ◽  
Steady Vibrations ◽  
South West Monsoon ◽  
Seismic Records ◽  
West Monsoon

Seismologists have often noted the appearance of pronounced microseisms in seismic records when the weather has been disturbed over a neighbouring sea. For instance, the late Dr. KLOTZ suggested a relationship between disturbed weather in the north Atlantic and the largest microseismic movements at Ottawa. Dr. HARRISON, writing in ' Nature,’ November 1, 1924, in continuation of a note* by the present writer, pointed out that well-marked microseisms in the Omori charts at Calcutta invariably confirmed other evidence in the case of the early stages of dangerous cyclones, and were sometimes noticed when the storm centre was so much as 1000 miles south of Calcutta. He did not, however, recall any instance in which microseisms were associated with ordinary rough weather or with an advance of the monsoon. On the other hand, “ investigation at Eskdalemuir of the possible connection between microseismical amplitude and the state of the sea at different points of the British coasts have yielded results of an inconclusive kind. For example, the correlation between the state of the sea and the Microseismic movements of a type, which were quite characteristic of the south-west monsoon period, made their first appearance in the seismograms generally in May with the advance of the monsoon in the south-east Arabian Sea, becoming more and more pronounced as the monsoon currents approached Bombay. They became less marked or disappeared during a temporary break in the monsoon and reappeared with the strengthening of the currents. They were more or less steady vibrations having periods ranging from 4 to 10 seconds.

First occurrence of the moray eel Gymnothorax prolatus Sasaki & Amaoka, 1991 (Teleostei: Anguilliformes: Muraenidae) from the northern Indian Ocean

2015 ◽  
Vol 8 ◽  
Author(s):  
Anil Mohapatra ◽  
Dipanjan Ray ◽  
David G. Smith
Keyword(s):  
Indian Ocean ◽  
Arabian Sea ◽  
Western Indian Ocean ◽  
Northern Indian Ocean ◽  
The North ◽  
First Occurrence ◽  
The Indian Ocean ◽  
First Time ◽  
North Western ◽  
Moray Eel

Gymnothorax prolatusis recorded for the first time from the Indian Ocean on the basis of four specimens collected in the Bay of Bengal off India and one from the Arabian Sea off Pakistan. These records extend the range of the species from Taiwan to the north-western Indian Ocean.

scholarly journals Recent emergence of CAT5 tropical cyclones in the South Indian Ocean

2018 ◽  
Vol 114 (11/12) ◽  
Author(s):  
Jennifer M. Fitchett
Keyword(s):  
Tropical Cyclone ◽  
Indian Ocean ◽  
Tropical Cyclones ◽  
Satellite Imagery ◽  
Storm Damage ◽  
The South ◽  
South Indian Ocean ◽  
The North ◽  
South Indian ◽  
Recent Emergence

The IBTrACS global best track data set endorsed by the World Meteorological Organization provides a valuable global record of tropical cyclone genesis, track and intensity, and spans 1842 to the present. The record is significantly more robust from the late 1970s onwards, as it is supported by satellite imagery. These records indicate that the first tropical cyclone in the South Indian Ocean to intensify to CAT5 status did so in 1994. This date is significantly later than the first CAT5 storms recorded in the IBTrACS database for the Atlantic Ocean (1924) and the North Pacific (1951) recorded from ship records, and half a decade later than those of the North Indian Ocean (1989) and South Pacific (1988), captured from satellite imagery. Following this late emergence, in the period 1990–2000, eight CAT5 tropical cyclones were recorded for the South Indian Ocean. A further four have been recorded for the period 2010–2015. This recent emergence of tropical cyclones attaining category five intensity in the South Indian Ocean is of significance for the forecasting of tropical cyclone landfall and the anticipation of storm damage for the developing economies that characterise the region. Although an increase in tropical cyclone intensity is frequently projected under global climate change scenarios, the dynamics for the South Indian Ocean have remained poorly understood. Notable are early results indicating an increased frequency and poleward migration of these CAT5 storms, concurrent with a poleward migration in the position of the 26.5 °C, 28 °C and 29 °C sea surface temperature isotherms in the South Indian Ocean. Significance: Category 5 tropical cyclones, the strongest category of storms, have only recently emerged in the South Indian Ocean. Since 1989, their frequency of occurrence has increased. This increase poses a heightened risk of storm damage for the South Indian Ocean Island States and the countries of the southern African subcontinent as a result of the strong winds, heavy rainfall and storm surges associated with these storms, and the large radial extent at category 5 strength.

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