Storm-Driven Warm Inflow Toward Ice Shelf Cavities—An Idealized Study of the Southern Weddell Sea Continental Shelf System

Abstract

Sudden peaks in south-westward wind strength (storms) have been observed to drive pulses of enhanced southward currents on the continental shelf east of the Filchner Trough. However, the link between wind and southward flow is not persistent, and it is uncertain which conditions favor the wind-driven pulses that typically bring modified Warm Deep Water southward toward the front of the Filchner Ice Shelf. We run a set of experiments in an idealized numerical model setup and find that storms induce a net southward “warm” (Θ > −1.5°C) volume transport in the trough region throughout the year. This is mainly explained by enhanced barotropic circulation on the shelf. The greatest storm-driven increase in southward heat transport occurs during summer and fall, with an exceptionally large increase in November and December due to storm-enhanced circulation on the shelf and seasonally varying heat content availability south of the shelf break. Analysis of ERA5-data shows that the number of storm days (wind speed >10 m s⁻¹) per year in the region co-vary with SAM. The positive trend in SAM can hence be expected to further enhance the importance of storm-driven southward heat transport toward the Filchner Ice Shelf cavity, which may have consequences for the basal melting.