Comparison of wave and current measurements to NORA10 and NoNoCur hindcast data in the northern North Sea

The objective of this study is to compare metocean design criteria for waves and currents based on measured and hindcast data and by that provide some insight in the expected differences. At the Norwegian Continental Shelf (NCS), the Norwegian Reanalysis Archive (NORA10) hindcast for wind and waves and the Northern North Sea Current Hindcast Study (NoNoCur) for currents are available. A comparison of NORA10 wave and NoNoCur current data to recent wave and current measurements during May 2011 to October 2015 at four locations in the northern North Sea has been done. For waves, significant wave height (H (s)), spectral peak period (T (p)), and wave direction are compared, and for currents, current speed (C (s)) and direction at two water depths. Scatter and qq-plots of H (s), T (p), and C (s) and directional roses, summary statistics, and time histories of H (s) and C (s) are provided. In addition, the extreme values of H (s) are estimated, the conditional log-normal distribution for T (p) given H (s) is discussed, and the H (s)-T (p) contour lines are established. Good agreement between NORA10 and measured wave data in the northern North Sea is demonstrated. The NORA10 H (s) is found to be slightly more conservative than the measured H (s). The NoNoCur data corresponds well to current measurements in the northern North Sea. However, the NoNoCur data does not correspond as good as the NORA10 data corresponds to measured data. Consequently, NORA10 can be recommended to be used for wave design criteria at NCS, while NoNoCur must be further developed and used with caution.