Water characteristics, mixing and circulation in the Bay of Bengal during southwest monsoon

Influence of the freshwater influx, the wind forcing and the Indian Ocean monsoon drift current on the property distributions and the circulation in the Bay of Bengal during southwest monsoon has been quantified. At the head of the Bay, waters of low salinity, affected by the freshwater influx, occupy the upper 90 m water column. The isohaline 34.0 × 10−3 separating these waters from those of underlying saline waters shoals southward gradually and outcrops around 14N, 10N and 6N in the western, central and southeastern regions of the Bay respectively. The wind-stress-curl-induced upwelling effect is confined to depth limits of 50–100 m as is supported by a band of cold (24°–19°C) water in the central Bay. In the southern and central regions of the Bay, the monsoon drift current feeds the large scale cyclonic gyre apart from maintaining the northward flowing boundary current in the eastern Bay. A warm (27°–23°C), saline (35.0–35.2 × 10−3) watermass is advected northeastward along with the monsoon drift current into the Bay up to 14N at the depth limits of 50–100 m. Below this depth, in the western Bay a well-defined southward flow in the form of a boundary current is documented. Intense vertical mixing is inferred at the zones of salinity fronts in the depth limits of 40–100 m and also at deeper depths (\u3e 2200 m) and elsewhere lateral mixing is predominant

Kinetics of Oxidation of Methyl Orange & Methyl Red by V(V)*

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Studies of upwelling along the West Coast of India using geopotential anomaly

As summer is the season of mixing: and winter the season of stratification in the Arabian Sea along the west coast of India, summer minus winter dynamic depth. which takes into account the integrated effects of temperature, salinity and pressure is considered to reveal regional differences of the intensity of upwelling: relative to winter situation. The areas of intensive upwelling a r e thus identified. Stabilities of water layers during summer are examined with respect to those during winter

Nitrogen in stone meteorites and terrestrial standards

Nitrogen contents have been determined by neutron activation method in stone meteorites and silicate standards. Leaching and sieving experiments on standards indicate that contamination from atmospheric nitrogen is negligible. For BCR-1 nitrogen contents show a range from 15 to 62ppm. The study includes 32 chondrites belonging to various classes and six achondrites. Nitrogen is high in C1 and C2 chondrites (500 to 1,000ppm) and in E chondrites (100 - 500ppm). C3 group shows variable amounts of nitrogen. Ordinary chondrites have similar nitrogen contents (~30pm) irrespective of their petrologic group. For all classes of meteorites, chondrules have lower nitrogen compared to the matrix. Dark phases of some gas- rich meteorites are enriched in nitrogen as compared to their light counterparts. Non-magnetic portions have slightly excess N compared to the magnetic portions. Correlation of N with C, In, Bi, Tl, Zn and Cd indicates the presence of two host phases for N

Observed changes in ocean acidity and carbon dioxide exchange in the coastal Bay of Bengal – a link to air pollution

Variations in surface water hydrographic properties and Dissolved Inorganic Carbon (DIC) were evaluated in the coastal Bay of Bengal using observations carried out during March–April 1991 and 2011, including 8 yr monthly time-series observations during 2005 and 2013. The coastal Bay of Bengal is characterised by relatively fresher, more basic and lower pCO2 in 1991 compared to 2011. The rates of decrease in pH, increase in DIC and pCO2 per decade were consistent with global trends in the Southwestern (SW) coastal Bay of Bengal, whereas rates in the Northwestern (NW) coastal Bay of Bengal were observed to be 3–5 times higher. The associated recent increase in sulphate and nitrogen aerosol loadings over NW Bay of Bengal from the Indo-Gangetic Plain and Southeast Asia during winter and spring may be mainly responsible for the increased acidity in recent years. Thus, this region, which was previously considered to be a significant sink for atmospheric CO2, now seems to have become a source of CO2 to the atmosphere

Excess <SUP>36</SUP>Ar in the Efremovka meteorite: a strong hint for the presence of <SUP>36</SUP>Cl in the early solar system

Noble gas studies of fine-grained silicate material of the Efremovka carbonaceous chondrite revealed the presence of excess 36Ar over and above the level expected due to contributions from the trapped and cosmic-ray-produced, both spallogenic and secondary neutron-induced, components. The observed excess in 36Ar can be best explained as due to in situ decay of 36Cl (&#964; = 0.43 Ma) in the analyzed samples and provides a strong hint for the presence of this now-extinct nuclide in the early solar system. Additional experiments that will confirm our observation are proposed. A conservative estimate of an initial 36Cl/35Cl of (1.4 &#177; 0.2) &#215; 10-6 at the time of formation of Efremovka silicates can be made from our data. If we consider a nucleosynthetic origin of 36Cl, the time interval between the last addition of freshly synthesized 36Cl to the solar nebula and the formation of some of the first silicate grains in the nebula could be estimated to be approximately 1 Ma

An Intrathermocline Eddy and a tropical cyclone in the Bay of Bengal

The Bay of Bengal, subjected to monsoonal forcing and tropical cyclones, displays a complex field of ocean eddies. On 5 December 2013 a sub-surface vortex or Intrathermocline Eddy (ITE) composed of water characteristic of the Andaman Sea was observed within the thermocline of the western Bay of Bengal. We propose that the ITE was the product of Tropical Cyclone Lehar interaction on 27 November 2013 with a westward propagating surface eddy from the eastern Bay of Bengal. While Lehar’s interaction with the ocean initially removes heat from the upper layers of the eddy, air-sea flux is limited as the deeper portions of the eddy was subducted into the stratified thermocline, inhibiting further interaction with the atmosphere. The ITE core from 30 to 150m is thus isolated from local air-sea fluxes by strong stratification at the mixed layer base, and its periphery is stable to shear instability, suggestive of longevity and the ability to carry water far distances with minimal modification

Cosmogenic effects in Mbale chondrite

This article does not have an abstract

Seasonal distribution of some oceanographic Parameters off southwest coast of India Relevant to pelagic fisheries

The temperature, salinity and oxygen distributions associated with the thermocline of the shelf and adjacent waters off the southwest coast of India are presented seasonwise. The seasonal differences in the location of the thermocline and the magnitude of the vertical temperature gradient within the thermocline are also presented and discussed. The commercially important pelagic fisheries of the waters are also discussed in the light of environmental conditions

Cosmogenic records in the recently fallen Devgaon (H4) chondrite

A stony meteorite fell in the village Devgaon, Bastar district, Chattisgarh, Central India on 2001 February 12. The meteorite was fully covered with fusion crust and weighed about 12 kg. Chemical composition, cosmogenic nuclear tracks, radionuclides and noble gases have been studied to determine its classification, the preatmospheric size and the irradiation history