Abstract The lack of sea ice in Antarctic coastal polynyas enables strong ocean‐to‐atmosphere heat fluxes and intense sea‐ice production. Although these features are primarily driven by intense offshore winds, their impact on local atmospheric conditions remains poorly understood. This study employs a high‐resolution polar Weather Research and Forecasting model configuration over the Prydz Bay region, East Antarctica, home to two major coastal polynyas: Cape Darnley and Mackenzie Bay polynyas. Sensitivity experiments over three winters (2014–2016) comparing simulations with and without polynyas reveal a marked and spatially confined atmospheric response. Polynya openings induce substantial surface heat release (up to 700 W m −2 ), warming near‐surface air by over 5 K and triggering convection and clouds. This results in a thickening of the atmospheric boundary layer and the development of stronger surface winds (up to 4 m s −1 ) that converge toward a low‐pressure anomaly. A particular emphasis is placed on the mechanisms controlling wind anomalies, using a dedicated wind tendency analysis. This diagnosis highlights that the processes involved depend on location and altitude within the polynya region and involve a balance between vertical mixing, horizontal advection, and pressure gradient forces—vertical mixing acting as the initiating factor. This study provides a novel modeling framework used to isolate the atmospheric response to coastal polynyas, overcoming limitations of previous studies and coarse‐resolution models. It offers new insights into the role of polynyas in modulating regional climate and improving understanding of the processes driving their dynamics.
Noël et al. (Thu,) studied this question.