Satellite Multi-Sensor Data Analysis of Unusually Strong Polar Lows over the Chukchi and Beaufort Seas in October 2017

Polar lows (PLs) are intense mesoscale weather systems that often cause severe storm winds in the Nordic Seas but were considered as being exceedingly rare Pacific Arctic region before sea ice decline. Here, we explore four PLs observed on 18–22 October 2017 Chukchi and Beaufort Seas—an area with an exceptionally sparse observation network. The study is based combined use of satellite microwave measurements, well infrared imagery, ERA5, MERRA-2 NCEP-CFSv2 reanalysis data sets. An unusually strong pair developed near marginal zone during a marine-cold air outbreak anomalously low extent conditions. moved southward mesocyclonic system called “merry-go-round”, under upper-level tropospheric vortex cold core. Multi-sensor measurements show that, mature stage, PL had near-surface wind speeds (W) close to hurricane force—over 30 m/s. Comparison analysis W distributions within strongest showed all sets reasonably reproduce median speed underestimate its extreme values by 15–23%. detected only two horizontal scales over 220 km. Tracks identified for good agreement ones obtained from images capturing main features propagation. For track event, ERA5 exhibited most accordance observations tracking error 50–60