Seasonality of tropospheric ozone and water vapor over Delhi,India: a study based on MOZAIC measurement data     

Lokesh K. Sahu  Shyam Lal  Valérie Thouret  Herman G. Smit 《Journal of Atmospheric Chemistry》2009,62(2):151-174

Tropospheric distributions of ozone (O₃) and water vapor (H₂O) have been presented based on the Measurements of OZone and water vapor by Airbus In-Service AirCraft (MOZAIC) data over the metro and capital city of Delhi, India during 1996–2001. The vertical mixing ratios of both O₃ and H₂O show strong seasonal variations. The mixing ratios of O₃ were often below 40 ppbv near the surface and higher values were observed in the free troposphere during the seasons of winter and spring. In the free troposphere, the high mixing ratio of O₃ during the seasons of winter and spring are mainly due to the long-range transport of O₃ and its precursors associated with the westerly-northwesterly circulation. In the lower and middle troposphere, the low mixing ratios of ∼20–30 ppbv observed during the months of July–September are mainly due to prevailing summer monsoon circulation over Indian subcontinent. The summer monsoon circulation, southwest (SW) wind flow, transports the O₃-poor marine air from the Arabian Sea and Indian Ocean. The monthly averages of rainfall and mixing ratio of H₂O show opposite seasonal cycles to that of O₃ mixing ratio in the lower and middle troposphere. The change in the transport pattern also causes substantial seasonal variation in the mixing ratio of H₂O of 3–27 g/kg in the lower troposphere over Delhi. Except for some small-scale anomalies, the similar annual patterns in the mixing ratios of O₃ and H₂O are repeated during the different years of 1996–2001. The case studies based on the profiles of O₃, relative humidity (RH) and temperature show distinct features of vertical distribution over Delhi. The impacts of long range transport of air mass from Africa, the Middle East, Indian Ocean and intrusions of stratospheric O₃ have also been demonstrated using the back trajectory model and remote sensing data for biomass burning and forest fire activities.  相似文献   

Plane symmetric inhomogeneous perfect fluid universe with electromagnetic field in Lyra geometry     

Anirudh Pradhan  Shyam Sundar Kumhar 《Astrophysics and Space Science》2009,321(2):137-146

A new class of plane-symmetric inhomogeneous cosmological models of perfect fluid distribution with electro-magnetic field based on Lyra’s geometry is obtained by considering a time dependent displacement field. The source of the magnetic field is due to an electric current produced along the z-axis. Only F ₁₂ is a non-vanishing component of electromagnetic field tensor. To get the deterministic solutions, the free gravitational field is assumed to be of Petrov type-II non-degenerate. It has been found that the displacement vector β(t) behaves like cosmological term Λ which is consistent with the recent observations of type Ia supernovae. It is also observed that β(t) affects entropy. Some geometric and physical behaviour of the models are also discussed in presence of magnetic field.   相似文献   

Inhomogeneous cosmological models with electromagnetic field in general relativity     

Raj Bali  Ghan Shyam Singh 《Astrophysics and Space Science》1987,134(1):47-54

In this paper inhomogeneous cosmological models with perfect fluid distributions in presence of electromagnetic field is obtained. Various physical and geometrical properties of the model in presence of electromagnetic field are also discussed.  相似文献   

Flexibility monitoring of offshore platforms     

S. Shyam Sunder  Seng Kiong Ting 《Applied Ocean Research》1985,7(1):14-23

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Numerical modeling of dredging effect on berthing structure     

Kasinathan Muthukkumaran  Ranganathan Sundaravadivelu 《Acta Geotechnica》2007,2(4):249-259

Piles and diaphragm wall-supported berthing structure on marine soils are loaded laterally from horizontal soil movements generated by dredging. The literature on the adequacy of the finite element method modeling of berthing structure to analyze their behavior during dredging is limited. This paper describes a finite element approach for analyzing the lateral response of pile and diaphragm wall during dredging. Piles are represented by equivalent sheet-pile walls and a plane strain analysis using the finite element method is performed. Results from the finite element method are compared with full-scale field test data. Full-scale field test was conducted on a bearing structure to measure the lateral deflection on pile and diaphragm wall for their full length using inclinometer during dredging in sequence. The finite element method results are in good agreement with full-scale field results. Conclusions are drawn regarding application of the analytical method to study the effect of dredging on piles and diaphragm wall-supported berthing structures.  相似文献   

An assessment of uncertainties in fatigue analyses of steel jacket offshore platforms     

James Kawamoto  S. Shyam Sunder  Jerome J. Connor 《Applied Ocean Research》1982,4(1):9-16

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Biostratigraphic Analysis of the Top Layer of Sediment Cores from the Reference and Test Sites of the INDEX Area     

Shyam M. Gupta 《Marine Georesources & Geotechnology》2000,18(3):259-262

Radiolarian fossil study in the sediment cores collected during the pre- and postdisturbance cruises of the Environmental Impact Assessment (EIA) Indian Ocean Experiment (INDEX) program of deep sea mining in the Central Indian Ocean Basin suggests a pronounced directional deposition of fossil radiolarians exhumed during the deep sea benthic disturbance experiment. The relative occurrences of the Stylatractus universus species that became extinct ~0.425 million years before present were mostly confined to the older and deeper strata of the sediment of the disturbance tract in the southwestern direction. This pattern is remarkable and suggests that the disturbance plume has been preferentially redeposited in the southwestern direction. This observation is in concurrence with the prevailing southwestern abyssal current during the disturbance experiment in the Central Indian Basin.  相似文献   

Climate change and water resources in the Bagmati River Basin,Nepal     

Mukand S. Babel  Shyam P. Bhusal  Shahriar M. Wahid  Anshul Agarwal 《Theoretical and Applied Climatology》2014,115(3-4):639-654

This paper characterizes potential hydrological impact of future climate in the Bagmati River Basin, Nepal. For this research, basinwide future hydrology is simulated by using downscaled temperature and precipitation outputs from the Hadley Centre Coupled Model, version 3 (HadCM3), and the Hydrologic Engineering Center's Hydrologic Modeling System (HEC-HMS). It is predicted that temperature may rise maximally during the summer rather than winter for both A2 and B2 Special Report on Emissions Scenarios (SRES) scenarios. Precipitation may increase during the wet season, but it may decrease during other seasons for A2 scenario. For B2 scenario, precipitation may increase during all the seasons. Under the A2 scenario, premonsoon water availability may decrease more in the upper than the middle basin. During monsoons, both upper and middle basins show increased water availability. During the postmonsoon season, water availability may decrease in the upper part, while the middle part shows a mixed trend. Under the B2 scenario, water availability is expected to increase in the entire basin. The analysis of the projected hydrologic impact of climate change is expected to support informed decision-making for sustainable water management.  相似文献