Spatiotemporal Variations and Associated Environmental Factors of Coastal Polynyas in the Kara–Laptev Seas from 2003 to 2025

Coastal polynyas in the Kara–Laptev Seas regulate winter air–sea exchange and sea-ice production, but neighboring polynya systems can behave differently. This study examines January–April variability of the Ob–Yenisey (OY), western Laptev Sea (WLS), and eastern Laptev Sea (ELS) polynyas from 2003 to 2025 using passive-microwave sea-ice concentration, ERA5 winds and air temperature, AMSR-MPR sea-surface temperature, TOPAZ4b sea-ice thickness, and AO/ENSO indices. The three regions show distinct spatiotemporal variations. The OY exhibits the only significant increase in accumulated polynya area (+1.72 × 104 km2 day a−1), the WLS has the largest interannual variability and the most frequent large-area events, and the ELS is most strongly concentrated in late March and April. NW has the clearest same-day or one-day-lead association with opening, consistent with wind-driven mechanical divergence, while coastline orientation and landfast-ice geometry are associated with differences in regional responses. Hierarchical partitioning (HP) assigns the largest daily relative statistical allocation to SST in the WLS and ELS; because this association is predominantly synchronous, it is interpreted as an ice–ocean state relationship rather than as a demonstrated antecedent control. Annual associations are more region dependent and include NW, T2M, SST, and SIT. AO is positively correlated with polynya activity, whereas ENSO has no consistent relationship.