A climatology of vessel icing for the subpolar North Atlantic Ocean

Vessel icing resulting from sea spray is a significant risk to maritime operations in the high latitudes. Despite the acknowledged risk that it imposes, there is limited climatological information that can be used for assessment and mitigation purposes. Here we use a parameterization of the icing rate that has been validated against observed cases of vessel icing and the Interim Reanalysis from the ECMWF (ERA-I) to develop the first climatology of the vessel icing for the wintertime subpolar North Atlantic. Three regions, the Labrador Sea, the Iceland Sea and the Greenland Sea, are examined in further detail. In all three regions, the icing rate and the frequency of occurrence of vessel icing increases towards the ice edge. The Labrador Sea is shown to have the highest risk of icing followed by the Greenland Sea and then the Iceland Sea. In particular, icing rates in excess of 4 cm h−1 are predicted to occur approximately 35%, 20% and 10% of the time during the winter in the Labrador, Greenland and Iceland Seas, respectively. On the monthly mean time scale, the severity of icing in all three regions is determined, to lowest order, by the location and depth of the Icelandic Low and its subsidiary feature, the Lofoten Low. In addition, heavy icing events in all three regions are shown to be associated with the passage of synoptic scale low-pressure systems that trigger cold air outbreaks.