On the Role of Barotropic versus Baroclinic Dynamics in Generating a Taylor Cap at Maud Rise, Weddell Sea

Abstract A Taylor cap originates from the flow’s impingement on a seamount and subsequent formation of a quasi-stagnant volume above it, which isolates water properties and weakens the stratification around it. Our focus is the Taylor cap at Maud Rise, Weddell Sea, as this region is prone to open-ocean polynyas. While previous studies have mainly examined the cap’s formation in a barotropic ocean, little attention has been paid to the role of baroclinic conditions, which are more relevant to the real world. We study the behavior of a Taylor cap in response to ambient stratification and inflow conditions in an idealized model setup. Our investigation explores scenarios ranging from a barotropic setup to a simplified, quasi-realistic stratification associated with thermal wind. In the stratified cases, we determine the relative roles of the barotropic (depth independent) and the baroclinic (depth dependent) flows and investigate the local response of stratification. Our results show that the Taylor cap is primarily generated by the deep barotropic flow and that the baroclinic component only forms a Taylor cap if the velocity at the depth of the seamount is sufficiently large. The baroclinic flow is, however, more effective at producing a doming of isopycnals over the seamount. The limited ability of Maud Rise in trapping water masses stems from the Rise’s large fractional height. Last, we show that higher inflow velocities lead to a shoaling of isopycnals and a reduction of upper-ocean stratification over the seamount, with implications for the potential local onset of deep convection.