Long-term variations in the monthly anomalies of different wave parameters off the western coasts of Scotland with respect to the regional dominant winds

Abstract EN

The present paper aims at drawing the possible long-term trends of variations in the monthly anomalies of ten wave parameters off the western coasts of Scotland.

The work is based on the hourly records of wind speed during 38 years (January 1973-December 2010) at Tiree meteorological station.

The investigated wave directions are set with respect to the dominant wind directions in the area of investigation.

These are the southern, the western, the south-western and the north-western wind directions.

The Pierson-Moskowitz wave spectrum equation in each wind direction has been used in order to calculate the main wave parameters.

The correlation factor between each examined parameter and the dominant wind speed has also been calculated.

All over the period of investigation, the monthly anomalies of the different wave parameters tended to be cyclic with different cycle periods.

This has only one exception: the wave peak and group velocities in the south-western wind direction.

January 1997 was a month of extreme values for the monthly anomalies of significant wave heights, peak period, wave energy and wave power in the western, south-western and north-western directions.

September, as previously appeared for the wind anomaly variations, is a common month of cycle reverse for the different wave anomalies in the four dominant directions in the area of interest.

In conclusion, the general behaviour of changes in waves off the western coasts of Scotland tends to be cyclic.

A longer time series, than that presently used, will be advantageous in order to strengthen this outcome with more robust investigation.

This concluded cyclic behaviour may positively impact on the engineering work within the wave energy resource off the western coasts of Scotland.