Abnormal Waves Generated by Polar Lows: Evaluation of Expectancy

Polar lows are the most intense subclass of mesocyclones developing at high latitudes above ice-free sea surface. These dangerous phenomena are capable of generating high wind waves even when cyclone is stationary. Moreover, as in case of tropical cyclones, a trapped-fetch effect may occur, i.e., when a polar low translates, waves in its right sector remain under high wind forcing for a prolonged time and grow to anomalous heights. Here we provide a model evaluation of the probability of appearance of such anomalous waves using a recently suggested wave enhancement criterion for moving extreme events and a new polar low climatology. As found, a significant part of the observed polar lows is capable of generating anomalously high waves. Frequency of appearance of abnormally high waves with heights exceeding given level (e.g. 6, 8, 10m) in the area of interest is presented.