Eruptive prominences of 1980 april 27 observed during STIP interval — X

Observations and analyses of two similar eruptive prominences on the north-east limb observed on 1980 April 27 at 0231 and 0517 UT, which are associated with the Boulder active region No. 2416 are presented. Both the eruptive prominences gave rise to white-light coronal transients as observed by C/P experiment of High Altitude Observatory on the Solar Maximum Mission. Type II and moving type IV radio bursts are reported in association with the first Hα eruptive prominence at 0231 UT. Both the Hα eruptive prominences showed pulse activity with a quasi-periodicity of about 2–4 min. We estimate a magnetic field in the eruptive prominence of about 100 G and a build-up rate ∼ 10²⁶ ergs^-1. The high build-up rate indicates that the shearing of the photospheric magnetic field, which fed the energy into the filament, was rapid. It is proposed that fast-moving Hα features must have initiated the observed coronal transients. From Hα, type II and coronal-transient observations, we estimate a magnetic field of 2.8 G at 1.9R⊙ from the disc centre, which agrees well with the earlier results.     

Time variability of the Hei 10830 Å line profile

We have studied the time-dependent behaviour of the Hei 10830 Å line. These studies show that (i) the fluctuations of the line width are uncorrelated with the equivalent-width fluctuations and (ii) the autocorrelation curves for the equivalent-width fluctuations are broader than those for line-width fluctuations. These results could be interpreted as the signatures of the eruption of density inhomogeneities, like spicules, into the altitudes of formation of the Hei 10830 Å line.     

Substitution of Natural Gas for Coal: Climatic Effects of Utility Sector Emissions

Substitution of natural gas for coal is one means of reducing carbon dioxide (CO₂) emissions. However, natural gas and coal use also results in emissions of other radiatively active substances including methane (CH₄), sulfur dioxide (SO₂), a sulfate aerosolprecursor, and black carbon (BC) particles. Will switching from coal to gas reduce the net impact of fossil fuel use on global climate? Using the electric utility sector as an example, changes in emissions of CO₂, CH₄,SO₂ and BC resulting from the replacement of coal by natural gas are evaluated, and their modeled net effect on global mean-annual temperature calculated. Coal-to-gas substitution initially produces higher temperatures relative to continued coal use. This warming is due to reduced SO₂ emissionsand possible increases in CH₄ emissions, and can last from 1 to 30years, depending on the sulfur controls assumed. This is followed by a net decrease in temperature relative to continued coal use, resulting from lower emissions of CO₂ and BC. The length of this period and the extent of the warming or cooling expected from coal-to-gas substitution is found to depend on key uncertainties and characteristics of the substitutions, especially those related to: (1) SO₂ emissions and consequentsulphate aerosol forcing; and (2) the relative efficiencies of the power plantsinvolved in the switch.     

Mean monthly wind driven climatological circulation model of the Bay of Bengal

A special feature of the Bay of Bengal circulation is its seasonal variation in response to the monsoonal winds. In the case of the Bay of Bengal, observationally very little is known about the large scale circulation. Theoretically, the problem of driving the circulation in the Bay of Bengal is more complex than that in other basins because of the presence of large quantities of fresh water discharge from Ganga-Brahmaputra-Meghna river systems, and also because the atmospheric driving forces even within a season are highly variable with frequent occurrences of tropical disturbances. Exploring the nature of the circulation in the Bay of Bengal is a problem of great importance in itself as well as for the critical role this region plays in the genesis of tropical disturbances which are the main source of large scale rainfall over the northern part of the Indian subcontinent. The surface circulation of the Bay of Bengal may, therefore, help in understanding the variation of rainfall over time scales ranging from the subseasonal to the interannual. Keeping this in view, an attempt was made towards the development of an oceanic climatological circulation model for the Bay of Bengal, which explains the seasonal variability of the currents. The model is fully non-linear and vertically integrated, with realistic basin geometry. The treatment of coastal boundaries involves a procedure leading to a realistic curvilinear representation of the western and eastern sides of the Bay of Bengal. This coastal representation has the advantage of taking into account the finer resolution in the shallow regions of the northern Bay. The model is forced by the monthly mean wind stress derived from 30 years (1950–79) of Comprehensive Oceanographic Atmospheric Data Sets (COADS). Special emphasis is given to the southern open boundary condition for the model. For this purpose, sensitivity experiments have been performed with six open boundary conditions and a comparative study of the results has been made. These sensitivity tests for the open boundary condition will help the development of a suitable coupled ocean-atmosphere model for this region. The model-generated main features are in general agreement with the known climatological circulation of the Bay of Bengal.     

Mapping and monitoring of urban landuse of Hisar Town,Haryana using remote sensing techniques

Aerial photographs for the year 1965 and 1975 and Landsat TM (FCC) 1986 data on 1:50,000 scale were used to map and monitor the pattern of growth and development of Hisar Town during the last 20 years. The different landuse categories identified are residential, commercial, industrial, recreational, vacant lands etc. The original shape of the town was nucleated one, but presently it is star-shaped, which is due to extension of the urban centre along the radiating roads. It has mainly elongated itself along the Delhi and Rajgarh roads. The presence of Government Livestock Farm (GLF), Equine Breeding Farm and HAU Farm towards North-west of the town has completely checked its growth on these sides. The total residential-cum-commercial area has nearly doubled during 1965–1975 and trebled by 1986. The change in net area under different types of urban land-use categories, described above has also been calculated. Degraded scrub lands and sandy wasteland on the fringes of the town have been identified where further development can be planned to avoid encroachment on good agricultural lands. Recommendations have been given for future urban planning of the town.     

Application of the SHE to catchments in India Part 2. Field experiments and simulation studies with the SHE on the Kolar subcatchment of the Narmada River

The results of SHE modelling of the 820 km² Kolar catchment in Madhya Pradesh, Central India are presented. The data collection, the associated field investigations, the calibration and the modelling results are discussed along with the assessment of model parameters. Based on the experiences obtained in this study from modelling and field experiments, the necessity of fieldwork and the hydrological realism of the final model representation of the basin are discussed.     

Confirmation of soil physiographic units through soil mineralogy studies in Yamuna alluvial plain,India

A confirmatory study of soil physiographic units identified through aerial photo interpretation technique, in Yamuna alluvial plain, Haryana is presented here. The area under study is part of Yamuna alluvial plain in Sonepat district, Haryana. Shanwal and Malik (1980) studied and mapped this area (semi-detailed) on 1:25,000 scale through areial photo interpretation technique. The soil profile samples of major soil physiographic units of the area were fractionated into sand, silt and clay. Detail mineralagical studies were carried out through electron microscopic and X-ray diffractometer studies in order to know their nature and origin of the parent material. X-ray diffraction data shows that mineralogy of different fractions (Sand, silt and clay) of soils samples, of different physiographic units were similar except Lavee. In this area mica is the dominant day mineral in the soils followed by Kaolinite, chlorite, vermiculite and smectite in decreasing order of their abundances. The occurance of fibrous minerals in coarse clay and silt fraction of soil samples of Lavee physiographic unit is the interesting feature of this area. The presence of fibrous minerals indicates that this overlain material designated as natural Levee in this area is not the alluvium brought down by the river Yamuna but is aeolian material flown from adjoining deseret of Rajasthan and deposited as stabilized sand dune. The fibrous minerals have been reported earlier in the desert of Rajasthan.     

Nonlinear Rayleigh-Taylor instability in partially ionized plasma and the equatorial spread-F

The nonlinear evolution of the collisional gravitation induced RayleighTaylor (R-T) instability in the equatorialF region is investigated taking into account the finite larmor radius (FLR) effects and the complete ion inertial term in ion equation of motion. A special class of coherent weakly nonlinear modes as solutions to the wave equation describing R-T instability driven modes is obtained. The leading nonlinear effects in the wave equation are found to appear throughV _l, the ion diamagnetic drift which essentially gives the FLR corrections. It is shown that the R-T modes in the equatorialF region can evolve into coherent, nonlinear, almost sinusoidal, stationary wave structures. These structures are found to travel with a constant phase velocity and to have slightly distorted sinusoidal shapes. These results seem to have a good agreement with many of the recent rocket and satellite observations of the equatorial spreadF irregularities.     

Stratigraphy and provenance of Late Palaeozoic diamictites in parts of Garhwal Lesser Himalaya,India

The Garhwal Lesser Himalayan Krol Belt contains two well developed diamictite horizons in the Late Palaeozoic Blaini Formation. Structureless and massive diamictites contain clasts of different shape, roundness and lithologies comprising mainly shale, slate, phyllite, quartzite, vein quartz and limestone dispersed in fine sandy argillaceous and calcareous matrix.Clast composition and petrography of the diamictites and other lithologies of the Blaini Formation reveal the presence of sedimentary and low grade metamorphic rocks in the provenance of the Blaini. The provenance seems to be the Lesser Himalayan terrain of the Simla Slate, Jaunsar and Shali-Deoban carbonates which had probably undergone structural deformation prior to the Late Palaeozoic. Two glacier advances deposited the diamictites near the shoreline of the Krol Basin during Late Palaeozoic.

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Zusammenfassung Im Krol Belt des Kleinen Himalaya sind in der jungpaläozoischen Blaini-Formation zwei Horizonte mit sedimentären Diamictiten enthalten. Die strukturlosen und massiven Diamictite enthalten Klastika verschiedener Form, Rundung und Lithologie. So findet man Schiefer, Phyllite, Quarzite, Gangquarze und Kalke in einer feinsandigen, tonigen Matrix mit Karbonatanteilen. Die Zusammensetzung der Klaste und die Petrographie der Diamictite sowie der übrigen Gesteine der Blaini-Formation zeigen die Anwesenheit von Sedimentgesteinen und schwach metamorphisierten Gesteinen im Einzugsbereich der Blaini-Formation. Dieser Bereich kann die Simla-Schiefer und die Jaunsar- und Shali-Deoban-Karbonate des Kleinen Himalaya mit umfassen, die vermutlich vorjungpaläozoisch metamorphisiert wurden. Während zweier Gletschervorstöße sind die Diamictite randlich im Krol-Becken während des Jungpaläozoikums abgelagert worden.

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Résumé Dans la ceinture de Krol de l'Himalaya mineur, la Formation de Blaini, d'âge Paléozoique supérieur, renferme deux horizons à diamictites sédimentaires. Celles-ci, massives et sans structure interne, contiennent des éléments clastiques de forme arrondi et lithologie différents; ce sont des schistes métamorphiques, des phyllites, des quartzites, du quartz-filonien et des calcaires disposés dans une matrice fine, argilosableuse avec participation carbonatée. La composition des éléments clastiques et la pétrographie des diamictites, comme celles des autres roches de la Formation de Blaini, montrent la présence de roches sédimentaires et de roches faiblement métamorphiques de même provenance que la formation de Blaini; cette provenance peut comprendre les schistes de Simla et les roches carbonatées de Jaunsar et de Shali-Deoban qui furent métamorphisées probablement avant le Paléozoique supérieur. C'est au cours de deux avancées glaciaires que les diamictites ont été déposées en bordure du bassin de Krol pendant le Paléozoique supérieur.

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