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41.
The significant wave height and wind speed derived for the period 1993–2010 from altimeter data sets over the Arabian Sea, Bay of Bengal, and the Indian Ocean categorized as six zones has been analyzed. The average variation of both significant wave height and wind speed is found to be almost stable for the period of study. The study reveals that the average wind speed increases by about 6cm/sec/year during monsoon and post monsoon in the southern Indian Ocean. The distribution of wind and waves was studied in the context of seasonal variations. In addition, the average inter-annual and intra-annual variations along with the statistical parameters such as standard deviation, and root mean square wave height for the six zones are also reported in this paper. 相似文献
42.
Shyam M. Gupta 《Marine Georesources & Geotechnology》2013,31(3):259-262
Abstract 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
43.
44.
The experimental and theoretical investigations on the behaviour of pontoon-type floating breakwaters are presented. A two-dimensional finite element model is adopted to study the behaviour of pontoon-type floating breakwaters in beam waves. The stiffness coefficients of the slack mooring lines are idealized as the linear stiffness coefficients, which can be derived from the basic catenary equations of the cable. The theoretical model is supported by an experimental programme conducted in a wave flume. The motion responses and mooring forces are measured for three different mooring configurations, and the results are reported and discussed in detail in this paper. The wave attenuation characteristics are presented for the configurations studied. 相似文献
45.
Dynamic pressures on inclined cylinders due to freak waves 总被引:1,自引:0,他引:1
The dynamic pressure distribution around a cylinder tilted along and against the principal wave direction is measured. The cylinder was exposed to the action of random waves in the presence and absence of extreme waves. Six inclinations from the vertical plane, three along and three against the wave direction, were considered. The cylinder in upright position was also studied. The variation of dimensionless peak pressure (pressure maximum/average highest one-third wave height, H1/3) with the relative wave height (maximum wave height/H1/3) for locations facing the wave and at the rear of the cylinder for different angles of inclinations of the cylinder are reported for the two kinds of waves mentioned earlier. The statistical properties of the different asymmetries in the pressure traces are also discussed. 相似文献
46.
Yuling Wu Udaysankar S. Nair Roger A. PielkeSr. Richard T. McNider Sundar A. Christopher Valentine G. Anantharaj 《Boundary-Layer Meteorology》2009,133(3):367-389
Prior numerical modelling studies show that atmospheric dispersion is sensitive to surface heterogeneities, but past studies
do not consider the impact of a realistic distribution of surface heterogeneities on mesoscale atmospheric dispersion. While
these focussed on dispersion in the convective boundary layer, the present work also considers dispersion in the nocturnal
boundary layer and above. Using a Lagrangian particle dispersion model (LPDM) coupled to the Eulerian Regional Atmospheric
Modeling System (RAMS), the impact of topographic, vegetation, and soil moisture heterogeneities on daytime and nighttime
atmospheric dispersion is examined. In addition, the sensitivity to the use of Moderate Resolution Imaging Spectroradiometer
(MODIS)-derived spatial distributions of vegetation characteristics on atmospheric dispersion is also studied. The impact
of vegetation and terrain heterogeneities on atmospheric dispersion is strongly modulated by soil moisture, with the nature
of dispersion switching from non-Gaussian to near-Gaussian behaviour for wetter soils (fraction of saturation soil moisture
content exceeding 40%). For drier soil moisture conditions, vegetation heterogeneity produces differential heating and the
formation of mesoscale circulation patterns that are primarily responsible for non-Gaussian dispersion patterns. Nighttime
dispersion is very sensitive to topographic, vegetation, soil moisture, and soil type heterogeneity and is distinctly non-Gaussian
for heterogeneous land-surface conditions. Sensitivity studies show that soil type and vegetation heterogeneities have the
most dramatic impact on atmospheric dispersion. To provide more skilful dispersion calculations, we recommend the utilisation
of satellite-derived vegetation characteristics coupled with data assimilation techniques that constrain soil-vegetation-atmosphere
transfer (SVAT) models to generate realistic spatial distributions of surface energy fluxes. 相似文献
47.
V. Sundar 《Ocean Engineering》1986,13(4)
A detailed analysis of visually observed wave data off Madras, South East Coast of India reported for a period of ten years is presented and discussed in this paper. The wave characteristics include wave height, wave period and its direction with respect to North. About five different standard distributions were tried to fit the observed data and found that the wave characteristics off Madras do not follow any of these. The wave power potential off Madras is also discussed. 相似文献
48.
49.
The influence of a square base placed at the bottom of a vertical cylinder on the wave induced forces and pressures on the cylinder is reported in this paper. In order to carry out this study, initially, the two dynamic variables on the cylinder in the absence of the base was studied so as to make sure the quality of measurements is satisfactory. The experimental results are compared with MacCamy and Fuchs' theory and the agreement found good. 相似文献
50.
The obstruction to flow around a pile placed in an erodible seabed causes scour leading to changes in the bed elevation in the vicinity of the pile. In the present investigation, scour around piles induced by the seabed current has been studied in a wave flume using model piles of diameters 50, 90 and 110 mm embedded in a silty clay soil bed. The particulate movement due to scour is time dependent and in case of sediments with particle sizes ranging upto clay fractions, the measurement of scour becomes extremely difficult. This paper presents a simplified experimental technique for the measurement of scour depth with time around a pile foundation in a silty clay soil. 相似文献