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The development of informal science learning programs (ISLPs) is a growing strategy among scientists seeking to engage communities. However, little scholarship exists on higher education ISLPs, limiting best practices for program development. This article explores the perceived impacts for student learners and scientist instructors of an international ISLP focused on marine science, using a mixed-methods approach of questionnaires, interviews, a task-based focus group, and participant observation. Learners perceived an increase in research skills and knowledge, and identified positive impacts associated with networking and forming connections. Learners did not significantly change their attitudes toward marine science or beliefs about careers in science. Instructors felt they helped advance their field and perceived positive impacts from cultural exchange, whereas only a few identified professional development impacts. This study suggests that higher education ISLPs should focus on creating space for different types of connections and increasing how scientists' participation is valued within the profession.

Tides and Earth-Moon system evolution are coupled over geological time. Tidal energy dissipation on Earth slows Earth's rotation rate, increases obliquity, lunar orbit semi-major axis and eccentricity, and decreases lunar inclination. Tidal and core-mantle boundary dissipation within the Moon decrease inclination, eccentricity and semi-major axis. Here we integrate the Earth-Moon system backwards for 4.5 Ga with orbital dynamics and explicit ocean tide models that are "high-level" (i.e., not idealized). To account for uncertain plate tectonic histories, we employ Monte Carlo simulations, with tidal energy dissipation rates (normalized relative to astronomical forcing parameters) randomly selected from ocean tide simulations with modern ocean basin geometry and with 55, 116, and 252 Ma reconstructed basin paleogeometries. The normalized dissipation rates depend upon basin geometry and Earth's rotation rate. Faster Earth rotation generally yields lower normalized dissipation rates. The Monte Carlo results provide a spread of possible early values for the Earth-Moon system parameters. Of consequence for ocean circulation and climate, absolute (un-normalized) ocean tidal energy dissipation rates on the early Earth may have exceeded today's rate due to a closer Moon. Prior to ∼3Ga , evolution of inclination and eccentricity is dominated by tidal and core-mantle boundary dissipation within the Moon, which yield high lunar orbit inclinations in the early Earth-Moon system. A drawback for our results is that the semi-major axis does not collapse to near-zero values at 4.5 Ga, as indicated by most lunar formation models. Additional processes, missing from our current efforts, are discussed as topics for future investigation.

Motivated by the importance of mixing arising from dissipating internal waves (IWs), vertical profiles of internal‐wave dissipation from a high‐resolution regional ocean model are compared with finestructure estimates made from observations. A horizontal viscosity scheme restricted to only act on horizontally rotational modes (such as eddies) is introduced and tested. At lower resolutions with horizontal grid spacings of 2 km, the modeled IW dissipation from numerical model agrees reasonably well with observations in some cases when the restricted form of horizontal viscosity is used. This suggests the possibility that if restricted forms of horizontal viscosity are adopted by global models with similar resolutions, they could be used to diagnose and map IW dissipation distributions. At higher resolutions with horizontal grid spacings of ∼250 m, the dissipation from vertical shear and horizontal viscosity act much more strongly resulting in dissipation overestimates; however, the vertical‐shear dissipation itself is found to agree well with observations. Plain Language Summary: Oceanic mixing impacts circulation, stratification (layering by density), and the uptake and transport of heat and nutrients. Over most of the ocean, mixing is caused by the breaking (turnover) of internal waves lying on the interfaces of density layers. Most ocean models do not contain a resolved internal wavefield, and therefore must parameterize internal wave (IW) mixing based upon external information. Recently developed high‐resolution ocean models with credible representations of internal waves may make it possible to map and understand global IW mixing without use of external information. Here we compare vertical profiles (profiles in depth) of IW dissipation in a regional model, which can be used to understand sensitivities to numerical schemes and grid spacings. With grid spacings that are attainable in global models, modeled dissipation profiles lie somewhat close to observed profiles, as long as certain choices are made within the numerical schemes. One numerical dissipation scheme is designed to realistically remove energy from eddy fields, which are the non‐wavelike motions in the ocean, and we have adapted this scheme to act less strongly on internal waves. Using this modified scheme, we find that high‐resolution global models may already be able to map IW dissipation. Key Points: Vertical profiles of internal wave (IW) dissipation in high‐resolution regional ocean simulations are compared with observed profilesProfiles in runs with a restricted form of horizontal viscosity and resolutions attainable in global models are close to observationsResults suggest high‐resolution global models can be used to map IW dissipation after numerical sensitivities are tested in regional models [ABSTRACT FROM AUTHOR]

This paper examines spectra of horizontal kinetic energy (HKE) in the surface and sub‐surface ocean, with an emphasis on internal gravity wave (IGW) motions, in global high‐resolution ocean simulations. Horizontal wavenumber‐frequency spectra of surface HKE are computed over seven oceanic regions from two global simulations of the HYbrid Coordinate Ocean Model (HYCOM) and three global simulations of the Massachusetts Institute of Technology general circulation model (MITgcm). In regions with high IGW activity, high surface HKE variance in the horizontal wavenumber‐frequency spectra is aligned along IGW linear dispersion curves. For both HYCOM and MITgcm, and in almost all regions, finer horizontal resolution yields more energetic supertidal IGW continuum spectra. The ratio of high‐horizontal‐wavenumber variance in semi‐diurnal and supertidal motions relative to lower‐frequency motions, a quantity of great interest for swath altimetry, depends on the model employed and the horizontal resolution within the model, implying that quantitative predictions of the partition between low‐ and high‐frequency motions taken from particular simulations should be treated with care. The frequency‐vertical wavenumber spectra, frequency spectra, and vertical wavenumber spectra from the models are compared to spectra computed from McLane profilers at nine locations. In general, MITgcm spectra match the McLane profiler spectra more closely at high frequencies (|ω| > 4.5 cpd). In both models, vertical wavenumber spectra roll off more steeply than observations at high vertical wavenumbers (m > 10−2 cpm). The vertical wavenumber spectra in such models is an important target for improvement, due to turbulence production and dissipation that takes place at high vertical wavenumbers. Plain Language Summary: Recently, a small but growing number of global ocean models have begun to employ simultaneous tidal and atmospheric forcing. At the same time, increasing supercomputer power has allowed for simulations of oceanic motions with increasing accuracy, increasing feature (spatial) resolution, and more frequent time slices. Global ocean models with fine grid spacing, and simultaneous tidal and atmospheric forcing, host a vigorous spectrum of high‐frequency waves that control mixing over most of the ocean water column, and are important for many operational oceanography challenges. As an example of the latter, high‐resolution global internal wave models have been used to study the relative partition of high‐frequency versus low‐frequency motions at the small horizontal scales that will be measured by the new Surface Water Ocean Topography mission. The partition described above depends on the model employed and the grid spacing employed within that model, meaning that conclusions about the partition are dependent on the model used to estimate it. Comparisons between the models and vertically profiling instruments indicate that resolving fine scale motions in the vertical direction, where ocean mixing takes place, is not yet handled well by the models. Modeling of fine‐vertical scale motions is therefore an important future research direction. Key Points: Vertical wavenumber spectra of internal gravity wave kinetic energy in two high‐resolution global models are compared to observed spectraModels under‐estimate motions at high vertical wavenumbers (small vertical scales), flagging this as a target for model improvementThe ratio of high‐ versus low‐frequency surface kinetic energy at small horizontal scales is dependent on the model and grid spacings employed [ABSTRACT FROM AUTHOR]

In recent years, efforts have been made to include tides in both operational ocean models as well as climate and earth system models. The accuracy of the barotropic tides is often limited by the model topography, which is in turn limited by model horizontal resolution. In this work, we explore the reduction of barotropic tidal errors in an ocean general circulation model (Modular Ocean Model version 6; MOM6) using sub‐grid scale topography representation. We follow the methodology from Adcroft (2013, https://doi.org/10.1016/j.ocemod.2013.03.002), which utilizes statistics from finer resolution topographic data sets to represent sub‐grid scale features with a light computational cost in a structured finite volume formulation. The geometric effect from sub‐grid scale topography can be introduced to the model with only a few parameters at each grid cell. The porous barriers, which are implemented at the walls of the grid cells, are used to modify transport between grid cells. Our results show that the globally averaged tidal error in lower‐resolution simulations is significantly reduced with the use of porous barriers. We argue this method is a potentially useful tool to improve simulations of tides (and other flows) in low‐resolution simulations. Plain Language Summary: In recent years, significant attention has been given to simulating tides in diverse ocean and climate models, because of the roles of tides in impacting sea levels. In order to better predict future sea level changes, it is therefore essential to improve the accuracy of surface tides simulated in numerical ocean models. One known source of errors that could impact the accuracy of modeled tides stems from the accuracy of ocean topography in the models, which relies on how many grid boxes (i.e., model resolution) are used to represent the complicated seafloor elevations. The model's resolution, however, is often constrained by the efficiency of computations. Our objective in this study is to enhance the portrayal of ocean topography at a given resolution to minimize tidal errors. To achieve this, we employ a technique known as "porous barriers," which uses approximations to mimic the effects of ocean topography that would be omitted in the models, without imposing significant computational burdens. Our findings demonstrate that this technique of porous barriers can substantially reduce tidal errors in our ocean model. We also expect a wider application of this technique to numerous other physical processes within the ocean. Key Points: The accuracy of tides in ocean models is affected by the representation of topography, which is constrained by model horizontal resolutionThe geometric effect of the sub‐grid scale topographic features can be approximated in the model with the porous barriersThe porous barriers can significantly reduce globally averaged errors for barotropic tides [ABSTRACT FROM AUTHOR]

Internal tides (ITs) play a critical role in ocean mixing, and have strong signatures in ocean observations. Here, global IT sea surface height (SSH) in nadir altimetry is compared with an ocean forecast model that assimilates de‐tided SSH from nadir altimetry. The forecast model removes IT SSH variance from nadir altimetry at skill levels comparable to those achieved with empirical analysis of nadir altimetry. Accurate removal of IT SSH is needed to fully reveal lower‐frequency mesoscale eddies and currents in altimeter data. Analysis windows of order 30–120 days, made possible by the frequent (hourly) outputs of the forecast model, remove more IT SSH variance than longer windows. Forecast models offer a promising new approach for global internal tide mapping and altimetry correction. Because they provide information on the full water column, forecast models can also help to improve understanding of the underlying dynamics of ITs. Plain Language Summary: Tidal flow over topographic features on the seafloor generates vertical displacements along the interfaces of ocean layers that have different densities. These vertical displacements at tidal frequencies are known as internal tides. Internal tide displacements are largest well below the sea surface, but also display a sea surface height (SSH) signature that is large enough to be measured by satellite altimeters. Removing internal tide signals from satellite altimeter SSH allows for a more accurate accounting of non‐tidal features, including slowly evolving ocean currents and eddies, that are also measured by altimeters. Here, we show that supercomputer ocean forecast simulations of the global internal tide field are able to remove internal tide SSH from satellite altimeter measurements with a skill level that is comparable to the skill of internal tide SSH removal based upon analysis of the satellite altimeter data itself. Thus, forecast models offer a complementary method for this important task. In addition, forecast models provide information on the entire ocean water column, not just the sea surface. Finally, the hourly outputs of forecast models allow for a greater variety of tidal analysis record lengths than can be achieved with altimeter outputs, which report sea surface height fields much less frequently. Key Points: Global ocean forecast models can accurately simulate both long‐term (phase‐locked) internal tides and their short‐term modulationsOcean forecast models offer a useful complement to empirical models for mapping internal tides and correcting altimetry for internal tidesIn regions of strong internal tides, optimal variance reduction in nadir altimetry is attained through short‐term tidal analyses (∼60 days) [ABSTRACT FROM AUTHOR]

The internal wave (IW) continuum of a regional ocean model is studied in terms of the vertical spectral kinetic energy (KE) fluxes and transfers at high vertical wavenumbers. Previous work has shown that this model permits a partial representation of the IW cascade. In this work, vertical spectral KE flux is decomposed into catalyst, source, and destination vertical modes and frequency bands of nonlinear scattering, a framework that allows for the discernment of different types of nonlinear interactions involving both waves and eddies. Energy transfer within the supertidal IW continuum is found to be strongly dependent on resolution. Specifically, at a horizontal grid spacing of 1/48°, most KE in the supertidal continuum arrives there from lower-frequency modes through a single nonlinear interaction, whereas at 1/384° and with sufficient vertical resolution KE transfers within the supertidal IW continuum are comparable in size to KE transfer from lower-frequency modes. Additionally, comparisons are made with existing theoretical and observational work on energy pathways in the IW continuum. Induced diffusion (ID) is found to be associated with a weak forward frequency transfer within the supertidal IW continuum. ID is also limited to the highest vertical wavenumbers and is more sensitive to resolution relative to spectrally local interactions. At the same time, ID-like processes involving high-vertical-wavenumber near-inertial and tidal waves as well as low-vertical-wavenumber eddy fields are substantial, suggesting that the processes giving rise to a Garrett–Munk-like spectra in the present numerical simulation and perhaps the real ocean may be more varied than in idealized or wave-only frameworks. [ABSTRACT FROM AUTHOR]

The decay of the low‐mode internal tide due to the superharmonic energy cascade is investigated in a realistically forced global Hybrid Coordinate Ocean Model simulation with 1/25° (4 km) horizontal grid spacing. Time‐mean and depth‐integrated supertidal kinetic energy is found to be largest near low‐latitude internal tide generation sites, such as the Bay of Bengal, Amazon Shelf, and Mascarene Ridge. The supertidal kinetic energy can make up to 50% of the total internal tide kinetic energy several hundred kilometers from the generation sites. As opposed to the tidal flux divergence, the supertidal flux divergence does not correlate with the barotropic to baroclinic energy conversion. Instead, the time‐mean and depth‐integrated supertidal flux divergence correlates with the nonlinear kinetic energy transfers from (sub)tidal to supertidal frequency bands as estimated with a novel coarse‐graining approach. The regular spaced banding patterns of the surface‐intensified nonlinear energy transfers are attributed to semidiurnal mode 1 and mode 2 internal waves that interfere constructively at the surface. This causes patches where both surface tidal kinetic energy and nonlinear energy transfers are elevated. The simulated internal tide off the Amazon Shelf steepens significantly near these patches, generating solitary‐like waves in good agreement with Synthetic Aperture Radar imagery. Globally, we find that regions of high supertidal energy flux also show a high correlation with observed instances of internal solitary waves. Plain Language Summary: Ocean tides generate internal waves at steep ridges and continental shelves in a stratified ocean. In some regions with strong tidal forcing, surface intensified stratification, and weak background rotation, these waves are observed to steepen into solitary‐like waves. In this process, energy is transferred from the tidal band to higher (supertidal) frequencies and wavenumbers. This study investigates "internal tide steepening" in a realistically forced global Hybrid Coordinate Ocean Model (HYCOM) simulation with a 4‐km horizontal grid spacing. In our simulation, supertidal internal wave energy accounts for about 5% of the total energy available to internal tides equatorward of ±25°. However in some regions, such as the Amazon Shelf and Bay of Bengal, this ratio can be as much as 50%. Along the internal tide beams, the supertidal energy transfers are enhanced in regular spaced "patches" where longer and faster mode 1 semidiurnal internal tides overtake the shorter and slower mode 2 internal tides. In these patches the surface velocities of these waves constructively superpose, enhancing the surface kinetic energy and nonlinear energy transfers. At the Amazon Shelf, sharp‐crested solitary‐like waves that emerge in these patches in the HYCOM simulation are in good agreement with satellite observations. Although nonlinear internal tides are simulated in our global ocean model simulation, higher resolutions are needed to better resolve the energy cascade to smaller scales. Key Points: Supertidal energy (>2.67 cycles per day [cpd]) is elevated at low latitudes, making up to 50% of total tidal energy (>0.9 cpd) in some areasSupertidal flux divergence and surface tidal energy reveal banding patterns due to the interaction between mode 1 and 2 internal tidesSupertidal flux divergence is due to energy transfers from internal tides to higher‐harmonic frequencies as computed with coarse graining [ABSTRACT FROM AUTHOR]