A climatology of low-level jets in the mid-latitudes and polar regions of the Northern Hemisphere

A wintertime climatology of the occurrence and characteristics of low-level jets (LLJs) in the Northern Hemisphere mid-latitudes and polar regions was developed. A LLJ detection algorithm was applied to 11years of Arctic system reanalysis data. The highest occurrence of LLJs was associated with strong gradients in topography and with the sea-ice edge. Sea areas fully covered with sea ice also favoured the occurrence of LLJs, however, these areas, including the central Arctic, had fewer LLJs than along the sea-ice edge. LLJs also occurred frequently in the seldom studied Sea of Okhotsk area.