Spatial Probability Characteristics of Waves Generated by Polar Lows in Nordic and Barents Seas

Abstract

Polar lows (PLs) are mesoscale, up to 1000 km, rather short lifetime (less than 15–30 h) cyclonic atmospheric systems formed in polar latitudes and associated with cold outbreak events. Strong winds, higher than 15 m/s, can then generate high surface waves which may pose danger to marine and coastal infrastructures. To investigate the probability of high waves generated by PLs in the Nordic and Barents Seas, analysis can be performed using available PL statistical distributions obtained from satellite passive microwave data, MODIS infrared imagery and ASCAT scatterometer data. Classical self-similar laws for wind waves development based on the extended duration concept are used to obtain first-guess estimates of significant wave height and the wavelength of waves generated by PL. All possible combinations of PL parameters (maximum wind speed, lifetime, diameter, translation velocity and direction of propagation) are considered to obtain the occurrence of waves exceeding specified levels, ranging from 2 to 15 m for significant wave height and from 100 to 500 m for wavelength. Particularly, PL-generated waves higher than 4 m occur up to 6 times a year, higher than 8 m occur up to 2–3 times a year, higher than 10 m occur up to once a year, the probability of 12 m waves is one event in several years and 15 m SWHs occur less than once in a decade. The area most affected by strong waves from PLs is the near shore zone around the Scandinavian peninsula, northward from the North Cape. The relative contribution of PLs in the formation of the waves field in the Nordic and Barents Seas is discussed.