Analysis of wave time series in the Estonian coastal sea in 2003–2014

• Main Author: Ülo Suursaar
• Format: Article
• Language: English
• Published: Estonian Academy Publishers 2015-11-01
• Series: Estonian Journal of Earth Sciences
• Subjects: wave modelling; wave measurements; fetch; storms; wind climate; Baltic Sea.
• Online Access: http://www.kirj.ee/public/Estonian_Journal_of_Earth_Sciences/2015/issue_4/earth-2015-4-289-304.pdf

Statistics of hindcast wave series were studied at eight differently exposed fetch-limited Estonian coastal sea locations (Harilaid, Kihnu, Kõiguste, Matsi, Neugrund, Sundgrund, Suurupi and Letipea). Based on episodic wave measurements obtained with the bottom mounted Recording Doppler Current Profiler in 2006–2014, a model for significant wave height was calibrated separately for those locations; using wind forcing data from Estonian coastal meteorological stations, a set of hourly hindcasts were obtained over the period from September 2003 to December 2014. Fourier analysis of monthly time series with regard to both average wave conditions and high wave events showed a distinct seasonality with specific amplitudes and the phases that differed by about a month between the locations. In addition, spectra of hourly time series indicated diurnal variations (24 and 12 h harmonics) and a consistent background noise following – 5/3 power law between the periods of 2 h and 4 days. Deseasonalized monthly data were used to analyse trends and extreme deviations (wavestorms). The possible trends, being obviously parts of longer variations, were not statistically significant over the studied 11 years. The lists of the most outstanding storms were different depending on the site.