ENSO’s changing grip on Bering Sea ice: The emerging control of the North Pacific meridional mode

Bering Sea winter sea ice (BSWI), vital for regional climate, ecosystem, and livelihoods, is significantly influenced by El Niño-Southern Oscillation (ENSO). Here we identify a shift in the ENSO-BSWI relationship. Pre-mid-1990s, traditional eastern Pacific ENSO dominated, driving a positive ENSO-BSWI linkage; Post-mid-1990s, more frequent central Pacific (CP) ENSO events reversed this relationship to negative. Observations and model experiments show CP El Niño coupled with positive-phase North Pacific Meridional Mode (NPMM) redirects poleward-propagating Rossby wave trains, enhancing Bering Sea southerlies. This suppresses ice advection, intensifies warm air intrusion, and reduces sea ice cover (SIC). Strengthened CP ENSO-NPMM coupling and heightened NPMM variability amplify this teleconnection, increasing its influence on winter SIC by 38.9% versus NPMM alone. Our findings underscore the growing role of subtropical and tropical Pacific climate interactions in subarctic sea ice variabil..., , , # ENSO’s changing grip on Bering Sea ice: The emerging control of the North Pacific meridional mode

Dataset DOI: [10.5061/dryad.1rn8pk16q](10.5061/dryad.1rn8pk16q)

## Description of the data and file structure

To examine the impact of anomalous surface winds on SIC, three ocean general circulation model (OGCM) experiments were conducted using the Parallel Ocean Program version 2 (POP2) within the Community Earth System Model version 1.2.2 (CESM1.2.2). These experiments consist of one control simulation (CTRL) and two sensitivity simulations (southerly and northerly wind experiments). The CTRL simulation is forced by global monthly climatological 10-meter winds, implemented with the G_NORMAL_YEAR component sets. The sensitivity experiments are identical to the CTRL, except that observed southerly or northerly wind anomalies are prescribed within the region spanning 160°E–160°W and 50°N–70°N from January to December. The surface wind anomalies are applied based on the partial regressio...