The spatio-temporal variability, trends, and drivers of winter Arctic polynyas

Polynyas, thin-ice or open water regions within the sea ice, have regularly been observed in the Arctic since satellite observations began in the 1970s. Their opening, in response to complex interactions between several drivers, significantly influences the regional weather and climate, ecosystem, and ocean circulation. Yet their monitoring at the pan-Arctic scale is rare since their detection is not trivial. Here, we use three sea ice satellite data products to detect and investigate major Arctic polynya events since 1978, focusing on their winter locations and total area. We compute the polynyas’ recurrence percentage, total number and area, varying the sea ice concentration (30 – 60%) and thickness (10 – 30 cm) thresholds to enhance our analysis robustness. We find that the most active polynya regions are along the coasts of the Laptev Sea, Kara Sea, Franz-Josef Land, northwestern Greenland, and Chukchi Sea. Both total and cumulative polynya areas have significant increasing trends in these regions and at the pan-Arctic scale between 1978 and 2024. In these regions, we find that wind speed and direction have a prominent one-day lag effect on polynya openings, suggesting that they are latent heat polynyas. The air temperature plays a preconditioning role in many regions, but seems to impact most the daily area extent, after the polynyas formed. Under rising temperatures and stronger extreme winds, our results suggest an increase in Arctic polynya activity, although polynyas might then extend into the open ocean, where different processes would drive their opening.