Setup and evaluation of a SWAN wind wave model for the Sea of Marmara

Abstract

A high-resolution SWAN wind wave hindcast model was implemented for the Sea of Marmara. For this, we focused firstly on the quality of two data sources for the wind forcing, viz., the ERA-Interim winds from the ECMWF and CFSR winds from the NOAA/NCEP. These were compared against wind measurements for 2013 collected at the Silivri offshore buoy in the north of the Sea of Marmara. A sensitivity analysis was performed to find the optimal numerical settings and wind source. This analysis showed that the CFSR winds are most suited for wave modeling in the Sea of Marmara. As the Sea of Marmara can practically be considered as deep water, we calibrated the SWAN model for different combinations of wind input and whitecapping source terms. The calibration was performed by varying the whitecapping coefficient for different combinations. The model setting giving the lowest errors and highest correlation via sensitivity analysis was determined as the calibrated model. Thirdly, the calibrated model was validated against measurements at the Silivri buoy for the years 2014, 2015 and 2016. This validation confirmed that the calibrated SWAN model with CFSR wind forcing performed better than the default settings. Lastly, the performance of the calibrated SWAN model was assessed for different wave height ranges, wind sources, annually and per season, their directional properties using wind and wave roses, their distribution function and Quantile Quantile plots along with extreme waves. The calibrated model offers almost the same extreme waves with different recurrent periods as the measurements.