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<title>Institute's contributions</title>
<link href="http://drs.nio.org/drs/handle/2264/1" rel="alternate"/>
<subtitle/>
<id>http://drs.nio.org/drs/handle/2264/1</id>
<updated>2017-07-09T18:01:28Z</updated>
<dc:date>2017-07-09T18:01:28Z</dc:date>
<entry>
<title>Upwelling intensity modulates N2O concentrations over the western Indian shelf</title>
<link href="http://drs.nio.org/drs/handle/2264/5112" rel="alternate"/>
<author>
<name>Sudheesh, V.</name>
</author>
<author>
<name>Gupta, G.V.M.</name>
</author>
<author>
<name>Sudharma, K.V.</name>
</author>
<author>
<name>Naik, H.</name>
</author>
<author>
<name>Shenoy, D.M.</name>
</author>
<author>
<name>Sudhakar, M.</name>
</author>
<author>
<name>Naqvi, S.W.A.</name>
</author>
<id>http://drs.nio.org/drs/handle/2264/5112</id>
<updated>2017-03-03T21:30:13Z</updated>
<published>2016-01-01T00:00:00Z</published>
<summary type="text">Upwelling intensity modulates N2O concentrations over the western Indian shelf
Sudheesh, V.; Gupta, G.V.M.; Sudharma, K.V.; Naik, H.; Shenoy, D.M.; Sudhakar, M.; Naqvi, S.W.A.
Repeat measurements of dissolved nitrous oxide (N&lt;sub&gt;2&lt;/sub&gt;O) along two transects of the western continental shelf of India in 2012 revealed high concentrations of 45±32 nM (off Kochi) and 73±63 nM (off Mangalore) during the summer monsoon (SM). N&lt;sub&gt;2&lt;/sub&gt;O concentrations increased nonlinearly during the peak of the SM upwelling, when low O&lt;sub&gt;2&lt;/sub&gt; (&lt;25 µM) conditions prevailed in the water column. Off Kochi, N&lt;sub&gt;2&lt;/sub&gt;O levels fell gradually from the fall intermonsoon (20±8 nM) to the winter monsoon (8.8±2 nM) and remained low (9.2±5.2 nM) through the spring intermonsoon season. The N&lt;sub&gt;2&lt;/sub&gt;O supersaturation off Kochi (574±720%) was presumably due to its high yield during sediment denitrification, whereas the higher N&lt;sub&gt;2&lt;/sub&gt;O supersaturation observed off Mangalore (1046±885%) was due to its production during denitrification in both the anoxic water column and the underlying sediments. Such distinctive biogeochemical behavior between these two shelf segments is at first augmented by the natural origin of intense upwelling at Mangalore relative to Kochi wherein suboxic to anoxic oxygen minimum zone waters spread from offshore to the shelf of Mangalore, over which the runoff and terrestrial nutrients supply acts in unison. Following new zonal extrapolation approach, our revised estimate of N&lt;sub&gt;2&lt;/sub&gt;O effluxes from the southwestern Indian shelf (7–14°N) was four times lower (0.019–0.039 Tg y-1) than previous estimate. Nevertheless, further studies are needed to refine the N&lt;sub&gt;2&lt;/sub&gt;O effluxes from the entire western Indian shelf to monitor its modification due to expansion/intensification of the coastal low-O&lt;sub&gt;2&lt;/sub&gt; zones and also to ascertain its actual N&lt;sub&gt;2&lt;/sub&gt;O contribution to the world oceans.
</summary>
<dc:date>2016-01-01T00:00:00Z</dc:date>
</entry>
<entry>
<title>Pseudofaults and associated seamounts in the conjugate Arabian and Eastern Somali basins, NW Indian Ocean- New constraints from high-resolution satellite-derived gravity data</title>
<link href="http://drs.nio.org/drs/handle/2264/5111" rel="alternate"/>
<author>
<name>Sreejith, K.M.</name>
</author>
<author>
<name>Chaubey, A.K.</name>
</author>
<author>
<name>Mishra, A.</name>
</author>
<author>
<name>Kumar, S.</name>
</author>
<author>
<name>Rajawat, A.S.</name>
</author>
<id>http://drs.nio.org/drs/handle/2264/5111</id>
<updated>2017-03-03T21:30:13Z</updated>
<published>2016-01-01T00:00:00Z</published>
<summary type="text">Pseudofaults and associated seamounts in the conjugate Arabian and Eastern Somali basins, NW Indian Ocean- New constraints from high-resolution satellite-derived gravity data
Sreejith, K.M.; Chaubey, A.K.; Mishra, A.; Kumar, S.; Rajawat, A.S.
Marine gravity data derived from satellite altimeters are effective tools in mapping fine-scale tectonic features of the ocean basins such as pseudofaults, fracture zones and seamounts, particularly when the ocean basins are carpeted with thick sediments. We use high-resolution satellite-generated gravity and seismic reflection data to map boundaries of pseudofaults and transferred crust related to the Paleocene spreading ridge propagation in the Arabian and its conjugate Eastern Somali basins. The study has provided refinement in the position of previously reported pseudofaults and their spatial extensions in the conjugate basins. It is observed that the transferred crustal block bounded by inner pseudofault and failed spreading ridge is characterized by a gravity low and rugged basement. The refined satellite gravity image of the Arabian Basin also revealed three seamounts in close proximity to the pseudofaults, which were not reported earlier. In the Eastern Somali Basin, seamounts are aligned along NE-SW direction forming ~300 km long seamount chain. Admittance analysis and Flexural model studies indicated that the seamount chain is isostatically compensated locally with Effective Elastic Thickness (T&lt;sub&gt;e&lt;/sub&gt;) of 3-4 km. Based on the present results and published plate tectonic models, we interpret that the seamounts in the Arabian Basin are formed by spreading ridge propagation and are associated with pseudofaults, whereas the seamount chain in the Eastern Somali Basin might have probably originated due to melting and upwelling of upper mantle heterogeneities in advance of migrating/propagating paleo Carlsberg Ridge.
</summary>
<dc:date>2016-01-01T00:00:00Z</dc:date>
</entry>
<entry>
<title>The origin and tectonic setting of precambrian greywacke of Ribandar-Chimbel, Goa, India: Petrological and geochemical evidence</title>
<link href="http://drs.nio.org/drs/handle/2264/5110" rel="alternate"/>
<author>
<name>Fernandes, G.Q.</name>
</author>
<author>
<name>Iyer, S.D.</name>
</author>
<author>
<name>Kotha, M.</name>
</author>
<id>http://drs.nio.org/drs/handle/2264/5110</id>
<updated>2017-03-03T21:30:11Z</updated>
<published>2016-01-01T00:00:00Z</published>
<summary type="text">The origin and tectonic setting of precambrian greywacke of Ribandar-Chimbel, Goa, India: Petrological and geochemical evidence
Fernandes, G.Q.; Iyer, S.D.; Kotha, M.
The Precambrian greywacke of Ribandar-Chimbel belonging to the Sanvordem Formation of the Goa Group, India, has been studied for petrography and analyzed for major trace elements. The greywacke is characterized by angular to sub-round grains of quartz, feldspar, biotite, chlorite and clay minerals. The abundance of clay in the matrix seems to have influenced the Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; content and the K&lt;sub&gt;2&lt;/sub&gt;O/Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; ratio. The variation diagrams indicate a decreasing trend of TiO&lt;sub&gt;2&lt;/sub&gt;, Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;, Fe&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; and MgO; whereas Na&lt;sub&gt;2&lt;/sub&gt;O and CaO exhibit a scatter which could be a result of the variable presence of feldspar within the sediments. The immobile elements, vanadium (25 to 144 ppm), nickel (up to 107 ppm) and chromium (up to 184 ppm), reflect abundance of clay minerals. The greywacke shows strongly fractionated REE patterns with LaN/YbN = 8 to 26 and with higher total REE abundances (up to 245 ppm). The low REE enrichment and depletion in heavier REE with prominent negative Eu anomaly (Eu/Eu*= 0.54 to 0.79) suggest a derivation of the greywacke from an old upper continental crust composed chiefly of felsic components. Petrological evidence and geochemical data suggest that the deposition of the greywacke largely took place in a deep to shallow basin that progressively changed from that of a continental island arc to an active continental setting
</summary>
<dc:date>2016-01-01T00:00:00Z</dc:date>
</entry>
<entry>
<title>Effect of submarine canyons on tsunami heights, currents and run-up off the southeast coast of India</title>
<link href="http://drs.nio.org/drs/handle/2264/5109" rel="alternate"/>
<author>
<name>JayaKumar, S.</name>
</author>
<author>
<name>ManiMurali, R.</name>
</author>
<author>
<name>Baldock, T.E.</name>
</author>
<id>http://drs.nio.org/drs/handle/2264/5109</id>
<updated>2017-03-03T21:30:11Z</updated>
<published>2016-01-01T00:00:00Z</published>
<summary type="text">Effect of submarine canyons on tsunami heights, currents and run-up off the southeast coast of India
JayaKumar, S.; ManiMurali, R.; Baldock, T.E.
Tsunami numerical model studies are mostly focused on inundation and run-up onto the coast. Fewer studies have been aimed at investigating role of submarine canyons on the tsunami heights, currents and run-up. The influence of submarine canyons and ridges in the Palar-Cauvery region off southeast coast of India on the 2004 December Boxing Day tsunami is considered in this study. Numerical modeling was carried out to study tsunami heights and currents in the vicinity of the submarine canyons as well as the variation of tsunami heights at 10 m water depth. Comparisons between the tsunami wave energy density at 10 m depth and the onshore run-up height observations showed a good correlation for select locations, with the run-up heights being about 3% of the wave energy density. However, the local topography in the run-up zone also strongly influences the local run-up, which reduces direct correlations between run-up and nearshore tsunami height.
</summary>
<dc:date>2016-01-01T00:00:00Z</dc:date>
</entry>
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