Ocean dynamics at the submesoscale play a key role in mediating upper-ocean energy dissipation and dispersion of tracers. Observations of ocean currents from synoptic mesoscale surveys at submesoscale resolution (250 m–100 km) from a novel airborne instrument (MASS DoppVis) reveal that the kinetic energy spectrum in the California Current System is nearly continuous from 100 km to sub-kilometer scales, with a k-2 spectral slope. Although there is not a transition in the kinetic energy spectral slope, there is a transition in the dynamics to non-linear interactions at scales of O(1 km). Barotropic kinetic energy transfer across spatial scales is enabled by interactions between the rotational and divergent components of the flow field at the submesoscale. Kinetic energy flux is intermittent but can be large, particularly at submesoscale fronts. Kinetic energy is transferred both downscale and upscale from 1 km in the observations of a cold filament.

In this work we present a unique set of coincident and collocated high- resolution observations of surface currents and directional properties of surface waves collected from an airborne instrument, the Modular Aerial Sensing System (MASS), collected off the coast of Southern California. High-resolution observations of near surface current profiles and shear are obtained using a new instrument, DoppVis, capable of capturing horizontal spatial current variability down to 128m resolution. This data set provides a unique opportunity to examine how currents at scales ranging from 1-100 km modulate bulk (e.g. significant wave height), directional and spectral properties of surface gravity waves. Such observations are a step toward developing better understanding of the underlying physics of submesoscale processes (e.g. frontogenesis and frontal arrest) and the nature of transitions between mesoscale and submesoscale dynamics.

The dynamical pathways of subduction, by which water from the oceanic surface mixed layer makes its way into the pycnocline, are influenced by both mesoscale (geostrophic) frontogenesis and submesoscale (ageostrophic and vertical) frontogenesis in the mixed layer. In frontal zones, subducted water masses that are tens of kilometers in extent can be identified in the pycnocline for days to months. Here, we explore the pathways and mechanisms for subduction with only weak surface forcing using a submesoscale-resolving numerical model of a mesoscale front. We use particle tracking to identify Lagrangian trajectories that exit the mixed layer. By identifying the subducting water parcels, we study the evolution of their dynamical properties from a statistical standpoint. The velocity and buoyancy gradients increase as water parcels experience frontogenesis and subduct beneath the mixed layer into the stratified pycnocline. We find that water parcels subduct within coherent regions along the front. These coherent subduction regions set the length scales of the subducted features. As a result, the vertical transport rate of a tracer has a spectrum that is flatter than the spectrum of vertical velocity. An examination of specific subduction events reveals a range of submesoscale features and frontogenesis processes that support subduction. Contrary to the forced submesoscale processes that sequester low PV anomalies in the interior, we find that PV can be elevated in subducting water masses. The rate of subduction that we estimate is of similar magnitude to previous studies (~100 m per year), but the pathways that are unraveled in this study along with the Lagrangian evolution of properties on water parcels, emphasize the role of submesoscale dynamics coupled with mesoscale frontogenesis.

Inequalities persist in the geosciences. White women and people of color remain under-represented at all levels of academic faculty, including positions of power such as departmental and institutional leadership. While the proportion of women among geoscience faculty has been catalogued previously, new programs and initiatives aimed at improving diversity, focused on institutional factors that affect equity in the geosciences, necessitate an updated study and a new metric for quantifying the biases that result in under-representation . We compile a dataset of 2,531 tenured and tenure-track geoscience faculty from 62 universities in the United States to evaluate the proportion of women by rank and discipline. We find that 27% of faculty are women. The fraction of women in the faculty pool decreases with rank, as women comprise 46% of assistant professors, 34% of associate professors, and 19% of full professors. We quantify the attrition of women in terms of a fractionation factor, which describes the rate of loss of women along the tenure track and allows us to move away from the metaphor of the ‘leaky pipeline’. Efforts to address inequities in institutional culture and biases in promotion and hiring practices over the past few years may provide insight into the recent positive shifts in fractionation factor. Our results suggest a need for 1:1 hiring between men and women to reach gender parity. Due to significant disparities in race, this work is most applicable to white women, and our use of the gender binary does not represent gender diversity in the geosciences.