Marine Operation Windows Offshore Norway

A study of the wave conditions in the North Sea, the Norwegian Sea and the Barents Sea is presented in this paper. For each region, one reference location for which there are buoy measurements is selected. For the selected locations, WAM10 hindcast data are obtained from the Norwegian Meteorological Institute (MET Norway). The hindcast data for each location cover the period from 1957 to 2014. First, the hindcast datasets were validated against available buoy measurements — both for extreme value predictions and for application of hindcast data for planning of marine operations. The validation was carried out considering the winter season and the summer season separately. For each season, the datasets for two consecutive months were used. A comparison of the time-series of the hindcast datasets against the buoy measurements showed that the hindcast datasets compared relatively well with the buoy measurements. However, a comparison of the statistical parameters of the hindcast datasets against the buoy measurements showed that the hindcast datasets are slightly conservative in the estimate of the significant wave height for the Barents Sea and the Norwegian Sea. Overall, the data compared well, and the hindcast datasets are therefore considered in the following analysis. Hindcast data from these 57 years show that the wave conditions in the selected Norwegian Sea location is harsher than the wave conditions in both the North Sea and the Barents Sea locations. This is in agreement with the general expected spatial trend in the wave climate on the Norwegian Continental Shelf (NCS). It was also observed that the wave conditions in the selected Barents Sea location are harsher than the wave conditions in the North Sea. These findings are also reflected in the NORSOK N-003 standard on “Actions and Action effects” (NORSOK, 2015). The weather windows for weather-sensitive marine operations, that is, operations with operational reference period not exceeding 72 hours, were established from the hindcast dataset for each of the locations. It was observed that the Norwegian Sea has shorter weather windows, especially in the winter seasons, compared to both the Barents Sea and the North Sea. It was expected that the operational windows would be shorter in the winter seasons in the Barents Sea, due to the occurrence of polar lows. However, the polar lows are few and cause more concern related to forecasting of the weather conditions to start actual marine operations. Generally, the month with the highest probability of weather windows exceeding 72 hours was found to be July for all three locations.