Pattern of seismic energy release from Koyna as seen at Gauribidanur     

H.S.S. Sharma  Gurajada S. Murty 《Tectonophysics》1982,83(3-4)

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Pi Gruis: Molecular identifications and spectral classification     

P. S. Murty 《Astrophysics and Space Science》1983,94(2):295-305

Identifications of the molecular absorption features in the visible spectrum of the S star Pi Gruis are presented. Moderate dispersion spectrum of π¹ Gru covering the region 5800–7300 Å, demonstrates the presence of a multitude of molecular bands. Wavelength measures of well over 150 red-degraded band heads are listed. Nearly 80% of the observed features are identified with the ZrO, LaO, YO, and CeO molecules. Many molecular bands due to ZrO, YO, and CeO are reported identified for the first time. Neither TiO molecular features nor any Ba compounds are detectable. As a consequence of the presence of bands due tos-process oxides and the absence of TiO bands, π¹ Gru may be classified as a pure S star. Observed predominance of the ZrO molecule suggests that both the phenomenon of Zr abundance enhancements and chemical equilibrium conditions with a carbon/oxygen ratio between 0.95 and 1.0 may be at play in the atmospheres of cooler pure S stars.  相似文献   

Nitrogen in diamond‐free ureilite Allan Hills 78019: Clues to the origin of diamond in ureilites     

V. K. Rai  S. V. S. Murty  U. Ott 《Meteoritics & planetary science》2002,37(8):1045-1055

Abstract— Nitrogen and noble gases were measured in a bulk sample and in acid‐resistant carbon‐rich residues of the ureilite Allan Hills (ALH) 78019 which has experienced low shock and is free of diamond. A small amount of amorphous carbon combusting at ≤500 °C carries most of the noble gases, while the major carbon phase consisting of large crystals of graphite combusts at ≥800 °C, and is almost noble‐gas free. Nitrogen on the other hand is present in both amorphous carbon and graphite, with different δ¹⁵N signatures of ?21%_o and +19%_o, respectively, distinctly different from the very light nitrogen (about ?100%_o) of ureilite diamond. Amorphous carbon in ALH 78019 behaves similar to phase Q of chondrites with respect to noble gas release pattern, behavior towards oxidizing acids as well as nitrogen isotopic composition. In situ conversion of amorphous carbon or graphite to diamond through shock would require an isotopic fractionation of 8 to 12% for nitrogen favoring the light isotope, an unlikely proposition, posing a severe problem for the widely accepted shock origin of ureilite diamond.  相似文献   

A corrected 3-D SPH method for breaking tsunami wave modelling     

Jinsong Xie  Ioan Nistor  Tad Murty 《Natural Hazards》2012,60(1):81-100

A 3-D large eddy simulation model that was first transformed to smoothed particle hydrodynamics (LES-SPH)-based model was employed to study breaking tsunami waves in this paper. LES-SPH is a gridless (or mesh-free), purely Lagrangian particle approach which is capable of tracking the free surface of violent deformation with fragmentation in an easy and accurate way. The Smagorinsky closure model is used to simulate the turbulence due to its simplicity and effectiveness. The Sub-Particle Scale scheme, plus the link-list algorithm, is applied to reduce the demand of computational power. The computational results show that the 3-D LES-SPH model can capture well the breaking wave characteristics. Spatial evolution features of breaking wave are presented and visualized. The detailed mechanisms of turbulence transport and vorticity dynamics are demonstrated as well. This application also presents an example to validate the SPH model.  相似文献   

Sea Level Changes Along Bangladesh Coast in Relation to the Southern Oscillation Phenomenon   总被引：1，自引：1，他引：0  

O. P. Singh Tariq Masood Ali Khan  Tad S. Murty  Md. Sazedur Rahman 《Marine Geodesy》2013,36(1):65-72

Interannual variations of sea level along the Bangladesh coast are quite pronounced and often dominate the long-term sea level trends that are taking place. The El Niño/Southern Oscillation (ENSO) induced variation is an important component of interannual mode of variations. The present article deals with the relationship between the sea level variations along the Bangladesh coast and the Southern Oscillation phenomenon. The mean tide level data of monsoon season (June to September) pertaining to Hiron Point (in Sundarbans) and Char Changa (on the mouth of Meghna River) have been analyzed and correlated to the Southern Oscillation Index (SOI). The annual variation of mean tide level in the coastal areas of Bangladesh reveals that the tide level reaches its peak during the monsoon season. The maximum tide level during the calendar year is recorded in August. Thus, it is not surprising that the inundation of the coastal belt of Bangladesh due to the floods is most common during the summer monsoon season, especially from July to September. Therefore, the sea level variations during the monsoon are of paramount importance to Bangladesh. The results of the present study show that both at Hiron Point and Char Changa there is a substantial difference between the mean tide level during the El Niño and La Niña monsoons. The mean tide level at Hiron Point is higher by about 5 cm during August of La Niña years as compared to that during the El Niño years. The difference at Char Changa, which is located at the mouth of Meghna River, is much higher. This is probably due to the increased fresh water discharge into the Meghna River during La Niña years. Thus at the time of crossing of a monsoon depression, the chances of widespread inundation are higher during a La Nin~a year as compared to that during an El Niño year. The Correlation Coefficients (CCs) between Mean Tide Levels (MTLs) at Hiron Point and Char Changa and the SOI during September (at the end of monsoon) are +0.33 and +0.39 respectively. These CCs are statistically significant at 90% and 95% levels, respectively. These results may find applications in the preparedness programs for combating sea level associated disasters in Bangladesh.  相似文献   

Effect of sea level rise on tidal circulation in the Hooghly Estuary,Bay of Bengal     

P. C. Sinha  Y. R. Rao  S. K. Dube  T. S. Murty 《Marine Geodesy》2013,36(4):341-366

The issue of sea level rise is receiving considerable attention all over the world. Although the Indian stations have shown mixed trends, a positive sea level trend has been noticed in the Hooghly Estuary, situated on the east coast of India. The Hooghly River serves as a navigable waterway to Calcutta and Haldia ports. The river is tidal for nearly 250 km. To study the water levels and tidal currents in the lower part of the Hooghly Estuary, from sea face at Sagar to Hooghly Point, a vertically integrated numerical model has been used. The model is fully nonlinear and uses a semiexplicit finite‐difference scheme to solve the basic hydrodynamic equations on a staggered grid. This model is coupled with a one‐dimensional model, which has been used for the upper estuary from Hooghly Point to Swarupganj, where the flow is unidirectional. The computed water levels and currents are found to be in good agreement with the available observations. This model is applied to study the alterations in tidal circulation for a rise and fall in the sea level. The results have shown a substantial increase in the amplitude and velocities of the tidal wave due to the sea level rise.  相似文献   

Tsunami warning system for the pacific coast of Canada     

W. J. Rapatz  T. S. Murty 《Marine Geodesy》2013,36(2-3):213-220

Abstract

The Tsunami Warning System for the Pacific Coast of Canada, which is part of the International Tsunami Warning System for the Pacific Ocean, is reviewed and major problems are identified. The efficiency of the present warning system is examined in view of the prediction by the international seismological community that major earthquakes are likely to occur in various seismic gaps around the Pacific rim in the near future. Whereas the present system is more or less adequate for the outer coast, at present there is no warning system for tsunamis generated locally in the Straits of Juan de Fuca and Georgia, or in Puget Sounds.  相似文献   

A new objective tsunami magnitude scale     

T. S. Murty  H. G. Loomis 《Marine Geodesy》2013,36(3):267-282

Abstract

Tsunami research has suffered considerably due to the lack of an objective magnitude scale. The Imamura‐Iida Grade Scale, although it has been used until now as a magnitude scale, is not objective, and it is more appropriate to call it a tsunami intensity scale. The tsunami magnitude scale proposed by Abe (1979) is also based on coastal tide gauge records, and this is not truly an objective magnitude scale. A new magnitude scale is proposed here, based on total tsunami energy, and it is demonstrated that this new scale will provide an adequate representation of the whole spectrum of tsunamis, starting from the negligible ones and including those that have devastated whole coastlines.  相似文献   

Investigation of the generation and propagation of low frequency internal waves: A case study for the east coast of India     

A.D. Rao  S.V. Babu  K.V.S.R. Prasad  T.V. Ramana Murty  Y. Sadhuram  D.K. Mahapatra 《Estuarine, Coastal and Shelf Science》2010

SAR (Synthetic Aperture Radar) images in the northwest Bay of Bengal indicate the existence of internal waves and their occurrence and intensity is topography dependent as indicated by in-situ data and satellite information. To complement and comprehend the observations, a three-dimensional Princeton Ocean Model is applied to study the generation and propagation of internal waves. The model domain is configured with a variable curvilinear grid and the input fields comprise bathymetry, initial temperature and salinity, wind stress, air-sea heat flux and tidal information. The numerical investigation indicated a predominant activity of internal waves in the north, and the rationale is three-fold. The first one could be the stable stratification due to fresh water discharge from head-bay major river system, secondly, the significant magnitude/range of the tides and finally, the bathymetry in the coastal waters off Paradip is about 12% shallower compared to that of Visakhapatnam and further south. The cumulative effect of these causes the predominance of internal waves in the north. The core of the energy is essentially in the low-frequency range and the model is able to simulate semi-diurnal and diurnal components reasonably well up to 6 h frequency (0.162 cph).  相似文献   

Morphology of Yardangs Within Nicholson Crater,Mars: Records of Past Fluvial and Aeolian Activities     

Ami J. Desai  S. V. S. Murty 《Journal of the Indian Society of Remote Sensing》2016,44(6):933-948

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