Wind-driven coastal polynya variability drives decadal ice-shelf melt variability in the Amundsen Sea

The ice shelves in the Amundsen Sea are being melted rapidly by warm Circumpolar Deep Water (CDW), causing sea-level rise. Ice-shelf melt variability is controlled by the speed of an undercurrent which flows along the continental slope and transports CDW onto the continental shelf. We study decadal variability of the undercurrent and ice-shelf melting using regional ice-ocean simulations. Output from a similar simulation has previously been published, but an error in the ERA5 atmospheric forcing has since been identified and is corrected in this study. Partly consistent with past findings, the undercurrent decadal variability is controlled by variability in coastal sea-ice freshwater fluxes. Perturbation experiments show that the sea-ice freshwater flux variability is driven by winds mechanically opening and closing coastal polynyas. A positive feedback mechanism between the undercurrent and ice-shelf melting is responsible for $25%$ of the resulting variability.