Several of Earth's intraplate volcanic provinces are hard to reconcile with the mantle plume hypothesis. Instead, they exhibit characteristics that are more compatible with shallower processes that involve the interplay between uppermost mantle flow and the base of Earth's heterogeneous lithosphere. The mechanisms most commonly invoked are edge‐driven convection (EDC) and shear‐driven upwelling (SDU), both of which act to focus upwelling flow and the associated decompression melting adjacent to steps in lithospheric thickness. In this study, we undertake a systematic numerical investigation, in both 2‐D and 3‐D, to quantify the sensitivity of EDC, SDU, and the associated melting to key controlling parameters. Our simulations demonstrate that the spatio‐temporal characteristics of EDC are sensitive to the geometry and material properties of the lithospheric step, in addition to the magnitude and depth‐dependence of upper‐mantle viscosity. These simulations also indicate that asthenospheric shear can either enhance or reduce upwelling velocities and the associated melting, depending upon the magnitude and orientation of flow relative to the lithospheric step. When combined, such sensitivities explain why step changes in lithospheric thickness, which are common along cratonic edges and passive margins, only produce volcanism at isolated points in space and time. Our predicted trends of melt production suggest that, in the absence of potential interactions with mantle plumes, EDC and SDU are viable mechanisms only for Earth's shorter‐lived, lower‐volume intraplate volcanic provinces.

Internal waves are the natural response of a stratified fluid to thermal or mechanical perturbations, whether periodic (e.g., tides) or localized in time (e.g., sudden wind gusts or thermal forcing), and are therefore ubiquitous in the ocean. Internal waves are associated with significant fluxes of energy (e.g., Waterhouse et al., 2014) and momentum (e.g., Naveira Garabato et al., 2013;Shakespeare & Hogg, 2019) that act to mix and force the ocean. The quantification of internal waves-and their attendant fluxes-is therefore of significant interest to the oceanographic community and has been the focus of many numerical modeling campaigns in recent years. Quantifying internal wave fluxes in the output of such models requires first identifying and separating the wave component of the flow from other signals.In lower resolution models, internal waves are readily identified as high-frequency (sub-daily) motion, as compared to the much slower (monthly to yearly) "mean" flow consisting of currents, jets and mesoscale eddies (e.g., the 0.  25 E model of Simmons & Alford, 2012). In such models, which do not resolve the high-frequency ocean submesoscale (usually identified as sub-10 km horizontal scales and daily timescales; e.g., Shcherbina et al., 2013;Thomas et al., 2008), internal waves are the only high-frequency signal, making their identification straightforward via a direct temporal filter at fixed points in space (an Eulerian filter). However, as computer power increases, models are simultaneously resolving both submesoscales

We examine the separate contributions to spurious mixing from horizontal and vertical processes in an ALE ocean model, MOM6, using reference potential energy (RPE). The RPE is a global diagnostic which changes only due to mixing between density classes. We extend this diagnostic to a sub-timestep timescale in order to individually separate contributions to spurious mixing through horizontal (tracer advection) and vertical (regridding/remapping) processes within the model. We both evaluate the overall spurious mixing in MOM6 against previously published output from other models (MOM5, MITGCM and MPAS-O), and investigate impacts on the components of spurious mixing in MOM6 across a suite of test cases: a lock exchange, internal wave propagation, and a baroclinically-unstable eddying channel. The split RPE diagnostic demonstrates that the spurious mixing in a lock exchange test case is dominated by horizontal tracer advection, due to the spatial variability in the velocity field. In contrast, the vertical component of spurious mixing dominates in an internal waves test case. MOM6 performs well in this test case owing to its quasi-Lagrangian implementation of ALE. Finally, the

Most of Earth's volcanism is concentrated at tectonic plate boundaries, representing the surface manifestation of either passive decompression melting at mid-ocean ridges (e.g., Phipps Morgan et al., 1987;Sengör & Burke, 1978) or volatile-induced melting at subduction zones (e.g., Peacock, 1990;Tatsumi et al., 1986). However, a significant and widespread class of volcanism occurs within plates or across plate boundaries. These so-called intraplate volcanic provinces cannot be explained through plate tectonic processes and require an alternative generation mechanism. Mantle plumes, hot, buoyant columns that rise from Earth's core-mantle boundary to its surface (e.g., Morgan, 1971), are commonly invoked to explain age-progressive volcanic tracks that grow older in the direction of plate motion. At the young end of these tracks, volcanism