Three dimensional dynamo theory in the magnetosphere

We have solved in this paper the three dimensional dynamo equation consistent with the conditions in the magnetosphere. The conductivity we have adopted here is that for a fully ionised but highly rarefied gas in a magnetic field. The velocity field is based on the measurements of the convection patterns made by different satellites. The solution obtained of the dynamo equation is presented here in the most general form so that it can be used when the various parameters are known to a higher degree of accuracy in future. We have then made a model calculation based on the particular solution of the inhomogeneous differential equation and have computed the components of the current as well as the isointensity curves in the midday-midnight meridional plane. as well as on the dawn-dusk meridional plane. These theoretical results have then been matched with observations.The passing away on December 30, 1971 of Professor Sarabhai prevented his seeing this final write up.     

Ex-seafarers shore-based employment: the current UK situation

The decline of the British shipping industry has had a significant impact on those sectors of the UK economy which have traditionally relied on ex-seafarers as a source of skilled labour. An in-depth study of the impacts of this problem was undertaken in 2003 to consider the implications of developments which have taken place in the industry since 1996. The UK economy's requirement for people with seafaring experience to fill land-based jobs was assessed, together with the implications of any shortfall. This paper considers the demand aspects of changes which have occurred since 1996.     

Influence of temperature on the physiological responses of the bivalve Brachidontes striatulus and its significance in fouling control.

Heat treatment offers an alternative method of fouling control to chlorination in power plants. In order to optimise such a procedure it is important to understand the responses of fouling organisms to elevated water temperatures. In this paper we report results of experiments on the lethal and sub-lethal effects of temperature on the bivalve Brachidontes striatulus which is one of the major foulants in the process seawater heat exchangers of Madras Atomic Power Station located at Kalpakkam, on the east coast of India. The important physiological activities, such as, oxygen consumption, filtration rate, byssus thread production and faecal matter production were studied at temperatures varying from 20 to 38 degrees C. Three different size groups [3-5 mm shell length (group 1), 6-10 mm (group 2), 11-15 mm (group 3)] of B. striatulus were used for the experiments. The results showed physiological activities were maximum at 35 degrees C, minimum at 20 and 38 degrees C. Physiological activities increased with size except for byssus thread production, which did not show any trend. Survival times showed a reduction from 30 h at 39 degrees C to < 1 h at 45 degrees C and were independent of body size.     

A Comparative Evaluation of the Geotechnical Index Properties of Clayey Sediments along the West Coast of India

Sediment core samples collected during geotechnical surveys along the West Coast of India in the near shore areas of Arabian Sea have generated data on the geotechnical index properties of clayey sediments up to nearly 5 m depth below seafloor. A comparative study of three sectors within themselves is attempted before carrying out a final evaluation between the sectors. Cohesive clayey sediments of Gujarat sector are comparable though widely variant in a few aspects; in the Maharashtra-Goa-Karnataka sector though, plasticity levels and clay type vary, and activity and consistency levels are quite similar. Though broadly comparable, the clayey sediments of Kerala-Tamilnadu sector have quite diverse characteristics that fail to conform to any particular pattern as each area has an exclusive set of geotechnical properties.     

Neogene oceanographic variations recorded in manganese nodules from the Somali Basin

A detailed study of a nodule from the Somali Basin dated by ²³⁰Th_excess was correlated with the paleoceanographic events recorded in Site 236 (Leg 24) Deep Sea Drilling Project (DSDP) cores. Tentative indications are that the phase of nodule accretion starting with the development of pillar structure at a depth of 20 mm in the nodule around 13 Ma coincides with increased Antarctic Bottom Water (AABW) flow and an elevated calciumcarbonate compensation depth (CCD).

The Late Miocene lowering of the CCD is represented by the mottled zones between 8 and 18 mm in the nodule is characterised by an abundant silicate component (>20%) of aeolian origin. The Miocene/Pliocene boundary (5 Ma) occurs at a depth of about 8 mm and is represented by the development of pillar structure and a minimum of aeolian dust (10.3%).

The increased biological productivity of the Somali surface water since the Middle Miocene is demonstrated by the increasing C_org content of the nodule (from 0.11 to 0.19%) towards its surface.     

A Study on the Delineation of Coral Reefs in Andaman and Lakshadweep Islands Using RISAT-1 Data

Coral reefs are one of the most diverse of all marine ecosystems and are often referred to as the “rainforests of the sea”. Though they cover less than one per cent of Earth’s surface, they are home to one quarter of all ocean species by providing food and shelter to them. Optical remote sensing has been widely employed for mapping and monitoring coral reefs. But the application of microwave remote sensing has been an alternate domain in this area. This study explores the possibility of utilizing synthetic aperture radar (SAR) data of Radar Imaging Satellite-I, India’s first indigenous microwave satellite to delineate the coral reefs in Andaman and Lakshadweep Islands in the Indian Ocean. The dual polarized data, after reducing the speckle has been classified to delineate the coral reefs in the vicinity of both islands. SAR has a performance comparable with passive optical sensors under favourable conditions of imaging, viz. optimum tidal current and surface winds. The study results are compared with the international coral reef reference map and are found to be highly promising, with an overall accuracy of 98.3% and a Kappa coefficient of 0.944 for fringing reefs in Andaman region. For the atolls in Lakshadweep region, the overall accuracy is found to be 92.99% and the Kappa coefficient is estimated at 0.7377. This study tries to explore a different horizon for microwave remote sensing in coral reef studies. It is seen that, optical and microwave remote sensing can provide a mutually supporting platform in coral reef delineation, in terms of imaging depth as well as climatic conditions.     

Satellite Image Resolution Enhancement Using Nonsubsampled Contourlet Transform and Clustering on Subbands

In this paper two new schemes for resolution enhancement (RE) of satellite images are proposed based on Nonsubsampled Contourlet Transform (NSCT). First one is based on the interpolation on band pass images obtained by applying NSCT on the input low resolution image. Similar to Demirel and Anbarjafari (IEEE Trans Geosci Remote Sens 49(6):1997–2004, 2011), as an intermediate step, the difference between approximation band and the input low resolution image is added with all the band pass directional subbands, to obtain a sharper image. This method is simple and computationally efficient but lacks sharp recovery of the edges due to the interpolation of band pass images. To overcome this, another method is proposed to obtain the difference layer, where dictionary is built using patches which are extracted from high resolution training image subbands. Similar patches from the dictionary are then clustered together. This method gives a much sharper image than the first method. Subjective and objective analysis of proposed methods reveals the superiority of the methods over conventional and other state-of-the-art RE methods.     

Size segregated aerosol mass concentration measurements over the Arabian Sea during ICARB

Mass concentration and mass size distribution of total (composite) aerosols near the surface are essential inputs needed in developing aerosol models for radiative forcing estimation as well as to infer the environment and air quality. Using extensive measurements onboard the oceanographic research vessel, Sagar Kanya, during its cruise SK223B in the second phase of the ocean segment of the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB), the spatial distribution of the mass concentration and mass size distribution of near-surface aerosols are examined for the first time over the entire Arabian Sea, going as far as 58°E and 22°N, within a span of 26 days. In general, the mass concentrations (M _T ) were found to be low with the mean value for the entire Arabian Sea being 16.7 ± 7 μg m^?3; almost 1/2 of the values reported in some of the earlier campaigns. Coarse mode aerosols contributed, on an average, 58% to the total mass, even though at a few pockets accumulation mode contribution dominated. Spatially, significant variations were observed over central and northern Arabian Sea as well as close to the west coast of India. In central Arabian Sea, even though the M _T was quite low, contribution ofs accumulation aerosols to the total mass concentration was greater than 50%. Effective radius, a parameter important in determining scattering properties of aerosol size distribution, varied between 0.07 and 0.4 μm with a mean value of 0.2 μm. Number size distributions, deduced from the mass size distributions, were approximated to inverse power-law form and the size indices (ν) were estimated. It was found to vary in the range 3.9 to 4.2 with a mean value of 4.0 for the entire oceanic region. Extinction coefficients, estimated using the number-size distributions, were well-correlated with the accumulation mode mass concentration with a correlation coefficient of 0.82.     

Talkoot: software tool to create collaboratories for earth science

“Open science,” where researchers share and publish every element of their research process in addition to the final results, can foster novel ways of collaboration among researchers and has the potential to spontaneously create new virtual research collaborations. Based on scientific interest, these new virtual research collaborations can cut across traditional boundaries such as institutions and organizations. Advances in technology allow for software tools that can be used by different research groups and institutions to build and support virtual collaborations and infuse open science. This paper describes Talkoot, a software toolkit designed and developed by the authors to provide Earth Science researchers a ready-to-use knowledge management environment and an online platform for collaboration. Talkoot allows Earth Science researchers a means to systematically gather, tag and share their data, analysis workflows and research notes. These Talkoot features are designed to foster rapid knowledge sharing within a virtual community. Talkoot can be utilized by small to medium sized groups and research centers, as well as large enterprises such a national laboratories and federal agencies.