Journal d'océanographie et de recherche marine
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Wave Hindcast Experiments Using Wam Cycle 4.5.3 - Validation with In situ Measurements in the North Indian Ocean

Swain J, Umesh PA, Rao AD and Mishra SK

In this investigation, the execution of the wave model WAM Cycle 4.5.3 was evaluated; based on the forcings by two distinct wind fields namely ERA-40 and QuikSCAT-NCEP Blended winds in the North Indian Ocean. Using the past analysed winds (hindcasting) and with boundary conditions generated from 1° x 1° global runs the wave model have been implemented for the North Indian Ocean from 50°E to 100°E and 0°N to 30°N. The model simulated parameters namely significant wave height (Hs), mean wave periods (Tc), mean wave direction, swell wave height (Hsw), swell wave period (Tsw) and swell wave directions are presented. Further, the predicted waves are compared against in-situ wave measurements. The simulated wave parameters obtained as outputs from numerical simulations such as Hs and Tc; collocated in space and time have been compared with buoy measurements in the Arabian Sea and Bay of Bengal with the aid of statistical error indicators. Comparison between the predicted and observed wave parameters are very encouraging, excepting the higher model estimates of significant wave height and the disagreement in lower wave heights at few buoy locations. Further, the sensitivity of the model to two different wind fields was analyzed and it is noted that the blended winds could accurately reproduce Hs and Tc at the buoy locations. The present study suggests that, WAM Cycle 4.5.3 model predictions are quite reliable for the Indian seas using the analysed wind fields such as ERA-40 and QuikSCAT/NCEP Blended wind fields. However, the performance of wave model was best when blended winds were used. Despite several limitations, the results reveal that the performance of third generation wave model is promising and the correlation and deviation of simulated and measured waves are critically inspected.