WAM validation studies in the North Indian Ocean using NCMRWF analyzed wind fields

With the launch of Oceansat-I (IRS-P4), it became a reality to carry out validations of third generation wave model 3g-WAM in the North Indian Ocean region using the IRS-P4 analyzed wind fields provided by the National Centre for Medium Range Weather Forecasting (NCMRWF), New Delhi, India. However, the model predicted wave fields were to be still analyzed and further validated using all available field measurements which was the primary task before the scientific community. This study, describes the wave model validation studies carried out at Naval Physical and Oceanographic Laboratory (NPOL), Cochin, India through a collaborative research programme between NPOL and Space Application Centre (SAC), as part of the IRS-P4, MSMR Utilization Programme. Under this collaborative programme, 3g-WAM wave hindcasts were carried out for the Indian Ocean from 30°E to 120°E and 30°S to 30°N using the analyzed winds of NCMRWF and appropriate open sea boundary inputs. WAM was executed using six hourly input fields over 1.5°x1.5° grid resolution. The outputs of the model such as wave height, peak wave period, mean wave period and mean wave directions were compared with the time-series buoy measurements of National Institute of Ocean Technology (NIOT), Chennai, India and other available measurements. Comparisons between the predicted and observed wave parameters were very encouraging. However, the model predictions of significant wave height were overestimated during the extreme wind and wave conditions. By and large, the WAM predictions were quite reliable for the south-west monsoon (May-September) periods in spite of the limitations. These validation studies have revealed that, the performance of WAM was satisfactory and the hindcast wave fields of WAM for the North Indian Ocean can be utilized for various user applications in the deep waters over 30 meter