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Minimal time ship routing is studied between Mumbai port (India) to Mombasa port (Kenya) using model hindcast wave climate over the Arabian Sea. With the launch of IRS-P4 (OCEANSAT-I), it became possible now to carry out routine wave hindcasting over the Indian Ocean. The MSMR channel of the satellite gives scalar wind, which is analyzed at NCMRWF, India, for converting to vector winds. The same is used as input to third-generation spectral wave model WAM for regional grid system for simulating the rough weather period of July 2000. This simulated wave climate formed the basis for computing effective ship velocity in the irregular seaway. This study gives a quantitative estimation of change in ship velocity in the open Indian Ocean for a bulk carrier. The minimal time path is charted using Dijkstra's algorithm for optimum route voyage. The optimum track information has broad scope for obtaining a safer route, least time route by avoiding delay in schedule with minimum fuel consumption. 相似文献
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This paper describes the development of a wave prediction system for the west Iberian coast. The implemented wave prediction system is based on two state-of-the-art spectral wave models, WAM for the ocean area and SWAN for the nearshore. However, because of its extended geographical space the SWAN model will include some generation effects in the coarse SWAN simulations, complemented by wave transformation effects near the coast. The system was validated by means of extended hindcast runs in various regions belonging to the continental Portuguese coastal environment, which were compared with buoy data, focusing on the extreme energetic events and both direct comparisons and statistical results are presented. 相似文献
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Raj Kumar Suchandra A. Bhowmick Sulagna Ray Vihang Bhatt Suhe Surendran Sujit Basu Abhijit Sarkar Vijay K. Agarwal 《Natural Hazards》2009,49(2):275-291
Accurate prediction of ocean surface waves is a challenging task with many associated difficulties. Availability of good quality
wind and wave information from satellite platforms inspired the scientific community to assimilate such data in various spectral
wave models for enhancing the accuracy of prediction. Over the Indian Ocean, which is the region of interest for the present
study, wave heights in extreme situation can go up to 12–14 m, thereby increasing the probability of coastal hazards. This
region is further governed by the southern ocean swells that propagate thousands of kilometers. These are, in general, not
well captured by the spectral wave models. Therefore, assimilation of altimeter data in open ocean wave model WAM has been
attempted with the aim of enhancing the quality of prediction of significant wave height. Further, simulated wave spectra
have been assimilated in a coastal wave model SWAN. This assimilation has been found to significantly improve the prediction
of the height of wind waves as well as swell waves.
V. Bhatt and S. Surendran are former students of Meteorology and Oceanography Group, Space Applications Centre, ISRO, Ahmedabad. 相似文献
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The present paper describes the set-up and application of the third-generation wave model — WAM Cycle 4 to the Black Sea. The wind fields are calculated by a regional atmosphere model (REMO), which was driven with the conditions from the global NCEP re-analysis project. These atmospheric data are used to force the state-of-the-art WAM model. The validation is done by comparison of wave model output against directional buoy measurements registered at three deep-water locations and wave gauge data taken at a point in intermediate depth near the Black Sea coast. The results reveal that agreement between modeled and measured data is satisfactory and the quality of the simulations increases under more energetic and severer wind and wave conditions. Following the validation, a 41-year wave hindcast was implemented spanning the period 1958–1998. 相似文献
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The performance of two well accepted formulations for white capping and wind input of third generation wave models, viz., WAM-3 and WAM-4, were investigated using parallel unstructured SWAN (PunSWAN). Several alternative formulations were also considered to evaluate the effects of higher order steepness and wave number terms in white capping formulations. Distinct model configurations were calibrated and validated against available in situ measurements from the Gulf of Mexico. The results showed that some of the in situ calibrated models outperform the saturation level calibrated models in reproducing the idealized wave growth curves. The simulation results also revealed that increasing the power of the steepness term can enhance the accuracy of significant wave height (Hs), at the expense of a higher bias for large waves. It also has negative effects on mean wave period (Ta) and peak wave period (Tp). It is also demonstrated that the use of the quadratic wave number term in the WAM-3 formulation, instead of the existing linear term, ameliorates the Ta underestimation; however, it results in the model being unable to reach any saturation level. In addition, unlike Hs and Tp, it has been shown that Ta is sensitive to the use of the higher order WAM-4 formulation, and the bias is decreased over a wide range of wave periods. However, it also increases the scatter index (SI) of simulated Ta. It is concluded that the use of the WAM-4 wind input formulation in conjunction with the WAM-3 dissipation form, is the most successful case in reproducing idealized wave growth curves while avoiding Ta underestimation of WAM-3 and a potential spurious bimodal spectrum of WAM-4; consequently, this designates another perspective to improve the overall performance of third generation wave models. 相似文献
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The disastrous effects of numerous winter storms on the marine environment in the North Sea and the Baltic Sea during the
last decade show that wind waves generated by strong winds actually represent natural hazards and require high quality wave
forecast systems as warning tools to avoid losses due to the impact of rough seas. Hence, the operational wave forecast system
running at the German Weather Service including a regional wave model for the North Sea and the Baltic Sea is checked extensively
whether it provides reasonable wave forecasts, especially for periods of extraordinary high sea states during winter storms.
For two selected extreme storm events that induced serious damage in the area of interest, comprehensive comparisons between
wave measurements and wave model forecast data are accomplished. Spectral data as well as integrated parameters are considered,
and the final outcome of the corresponding comparisons and statistical analysis is encouraging. Over and above the capability
to provide good short-term forecast results, the regional wave model is able to predict extreme events as severe winter storms
connected with extraordinary high waves already about 2 days in advance. Therefore, it represents an appropriate warning tool
for offshore activities and coastal environment. 相似文献
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This article uses a comparison of four different numerical wave prediction models for hindcast wave conditions in Lake Michigan during a 10-day episode in October 1988 to illustrate that typical wave prediction models based on the concept of a wave energy spectrum may have reached a limit in the accuracy with which they can simulate realistic wave generation and growth conditions. In the hindcast study we compared the model results to observed wave height and period measurements from two deep water NOAA/NDBC weather buoys and from a nearshore Waverider buoy. Hourly wind fields interpolated from a large number of coastal and overlake observations were used to drive the models. The same numerical grid was used for all the models. The results show that while the individual model predictions deviate from the measurements by various amounts, they all tend to reflect the general trend and patterns of the wave measurements. The differences between the model results are often similar in magnitude to differences between model results and observations. Although the four models tested represent a wide range of sophistication in their treatment of wave growth dynamics, they are all based on the assumption that the sea state can be represented by a wave energy spectrum. Because there are more similarities among the model results than significant differences, we believe that this assumption may be the limiting factor for substantial improvements in wave modeling. 相似文献
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We revisit the surge of November 1977, a storm event which caused damage on the Sefton coast in NW England. A hindcast has been made with a coupled surge-tide-wave model, to investigate whether a wave-dependent surface drag is necessary for accurate surge prediction, and also if this can be represented by an optimised Charnock parameter. The Proudman Oceanographic Laboratory Coastal Modelling System-Wave Model (POLCOMS-WAM) has been used to model combined tides, surges, waves and wave-current interaction in the Irish Sea on a 1.85 km grid. This period has been previously thoroughly studied, e.g. Jones and Davies [Jones, J.E., Davies, A.M., 1998. Storm surge computations for the Irish Sea using a three-dimensional numerical model including wave-current interaction. Continental Shelf Research 18(2), 201–251] and we build upon this previous work to validate the POLCOMS-WAM model to test the accuracy of surge elevation predictions in the study area. A one-way nested approach has been set up from larger scale models to the Irish Sea model. It was demonstrated that (as expected) swell from the North Atlantic does not have a significant impact in the eastern Irish Sea. To capture the external surge generated outside of the Irish Sea a (1/9° by 1/6°) model extending beyond the continental shelf edge was run using the POLCOMS model for tide and surge. 相似文献
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