We present an analysis of the electrokinetic coupling equations for capillary flow developed in a previous work by the same authors where an extension to Pride's theory encompassing partially saturated porous rocks was derived. One of the main hypotheses of the model establishes that the non-wetting fluid phase must be connected across the averaging volume, which may not be the case near full wetting phase saturation. To overcome this limitation we develop new expressions for the model

Eulerian and semi-Lagrangian schemes are often used to simulate the Earth’s oceans and atmosphere, but it has been proposed that a fully Lagrangian approach may be more computationally efficient in terms of simulation runtime. In this presentation, a Lagrangian particle-based framework is proposed to perform global high-resolution fluid simulations on the sphere. Our approach builds off of existing techniques that represent particles as power cells (a generalization of Voronoi cells) to simulate incompressible fluids. The efficiency of the power diagram calculation is of utmost importance since this Lagrangian framework requires calculating several power diagrams at each time step of the fluid simulation. For now, we focus on geometrical aspects of this problem, particularly the fast calculation of power diagrams on the sphere. We present a parallel technique for calculating Voronoi and power cells on the sphere by applying the radius of security theorem along with a hierarchical triangular mesh to compute the nearest neighbors of every site. Next, we compare our approach with existing techniques for computing spherical Voronoi diagrams. Depending on the distribution of the sites, our approach enables 10 million Voronoi cells to be calculated in about 12 - 15 seconds on a 10-core laptop (about 9 - 10 seconds to compute the nearest neighbors and 3 - 5 seconds to compute the Voronoi diagram), which is faster than MPI-SCVT (3x), STRIPACK (76x) and the method used by scipy.spatial.SphericalVoronoi (5x). Finally, we use our technique for calculating power diagrams to demonstrate a particle-based approach for simulating incompressible fluids on a rotating sphere using the Gallouët-Mérigot scheme and discuss future plans to extend the framework to simulate more general fluid flows.

Solar activity can be captured by obaservations of Extreme Ultra Violet irradiance. The solar radio flux is often used as an index for the Extreme Ultra Violet irradiance, chiefly because of the ease of measuring it from the earth. Often referred to as the $F_{10.7}$, the value of the radio flux is enhanced by its long observation period that dates as far back as 1947. Forecasts of this proxy of solar activity can also be used as inputs to impact models. Impact models include atmospheric density models that are valuable for predictions of drag in near-earth satellite orbits. The National Oceanic and Atmospheric Administration (NOAA) has been providing point forecasts of $F_{10.7}$ since 1997 on a weekly basis. Meanwhile, the past decade has witnessed new efforts to develop forecasting models of the $F_{10.7}$. The majority of these efforts take a deterministic approach to evaluate their respective forecasting performance. This paper provides a statistical baseline for producing and evaluating probabilistic forecasts of solar activity. The key idea is to acknowledge variations in forecast uncertainty over the solar cycle and convert point forecasts into probabilistic distributions. We contrast ways of producing such distributions and argue that the level of solar activity should be taken into account. The baseline distributions are climatology and distributions based on a state-dependent persistence model. A probabilistic version of NOAA forecasts is produced and evaluated against these baselines to infer their information content at all the lead times considered. The lead times considered are 1 to 27 days.

Global uncoupled storm-resolving simulations using the ICOsahedral Non-hydrostatic (ICON) model with prescribed sea surface temperature show a double band of precipitation in the Western Pacific, a feature explained by reduced precipitation over the warm pool. Three hypotheses using an energetic framework are advanced to explain the warm pool precipitation bias, and they are related to 1) high-cloud radiative effect, 2) too-frequent or highly efficient precipitating shallow convection, and 3) surface heat fluxes in light near-surface winds. Our results show that increasing surface heat fluxes in light near-surface winds produce more precipitation over the warm pool and a single precipitation band in the Western Pacific. Further improvements were stronger near-surface winds over the Western Pacific and a moister and warmer tropical troposphere, but these improvements were not enough to fully overcome the existing biases. Simulations with an increased high-cloud radiative effect did not affect precipitation over the warm pool, and according to the energetic framework, due to compensation between the radiative effect and both, surface heat fluxes and circulation. Moreover, the representation of shallow convection did not affect warm pool precipitation. Thus, our results show the importance of the feedback between winds, surface heat fluxes, and convection for a correct representation of the oceanic tropical rainbelt structure in regions of weak sea surface temperature gradient as the warm pool.

A document by Malasani Chakradhar Reddy. Click on the document to view its contents.

As the use of unmanned aerial vehicles (UAVs) expands, wind and turbulence observations near surface in urban areas are crucial for safe flight planning. In summer 2021, a field campaign was conducted in the suburbs of Seoul, South Korea, using UAV equipped with a sonic anemometer. Horizontal winds were measured at 1-Hz up to 150 m above ground level during research flights. From 1-Hz winds, the cube root of energy dissipation rate (EDR), an objective measure of turbulence intensity, was computed using inertial dissipation methods. Stronger turbulence was observed at lower altitudes near surface than at higher altitudes, likely due to dominant surface shears. Regionally, higher EDRs were found in walk roads along rivers compared to building-surrounded areas, likely due to flows blocked by buildings. Current results highlight need for strategic UAV flight planning considering turbulence at different altitudes and urban structures, supporting safer UAV flight routing.

The high latitude oceans are problematic for satellite estimations of precipitation due to the high frequency of occurrence of light drizzle and snowfall. Microwave radiometric observations are sensitive to integrated cloud water path but lack skill in distinguishing precipitation onset from cloud water and cloud ice due to radiation scattering. Precipitation radars to date have lacked sensitivity to drizzle and cloud radars have suffered from both the uncertainties inherent in Z-R relations and poor sampling due to nadir-only scans. This study optimally combines coincident active and passive microwave observations from CloudSat’s Cloud Profiling Radar (CPR) and the Advanced Scanning Microwave Radiometer (AMSR2) to resolve cloud and hydrometeor distribution parameters and to force consistency between the two independent sets of coincident observations. The result is an estimation of drizzle frequency and intensity that are consistent with both the CPR and AMSR2 observations for the high latitude oceans. This study finds that zonal means of retrieved high-latitude drizzle below 0.25 mm hr-1 from these combined observations (0.263 mm day-1) falls slightly above those of CloudSat estimates (0.244 mm day-1), provided by the 2C-RAIN-PROFILE and 2C-SNOW-PROFILE products (Lebsock, 2018; Wood and L’Ecuyer, 2018), and far below that of radiometer-only estimates (0.920 mm day-1) provided by GPROF (Kummerow et al., 2015).

A document by Jordan Laser. Click on the document to view its contents.

A document by Christine Olson. Click on the document to view its contents.

Ocean Networks Canada (ONC) straddles the nexus between community relations, infrastructure installations, and data storage. As such, ONC has opportunities to partner with Indigenous communities and incorporate CARE Principles (Collective Benefit, Authority to Control, Responsibility, Ethics) from the point of engagement through to implementation and curation of Indigenous data. To further our commitment to CARE, ONC is implementing Local Contexts label compatibility into our metadata and dataset architecture. Local Contexts can help Indigenous communities reassert their cultural authority to dictate to users how their own data are to be collected, managed, displayed, accessed, and used (Local Contexts, 2024) while hosted on ONC’s data repository. Data agreements are binding agreements between ONC and our various partners – including Indigenous communities – to establish conditions and rules for our continued collaborations. Sensitive datasets can be restricted at the discretion of the community, and a pathway exists in which data users can make requests if they wish to pursue access to the restricted data. ONC as a custodian and distributor does not hesitate to relinquish ownership of data to further promote Indigenous data sovereignty and governance. A stake in ownership of community-based monitoring data is not a necessity for ONC but is rather a discussion to have with our Indigenous partners. License and Policy attribution to the data can be decided during negotiation of the data agreement between parties, where we can then apply Creative Commons (2024) Licenses or other licenses as deemed fit by the community. These processes are set during the consultation phase, however. Indigenous communities are dynamic, and their needs can change over time. What happens if a community wishes to change one of these previously agreed-upon rules? Local Context Labels are one way for Indigenous communities to flex their authority to control the data which they own. When a community changes their project labels, it will get picked up in ONC’s dataset metadata and landing pages. In practice, this is one method communities can leverage to prompt new amendments of agreements by ONC. These labels can also be used by communities to express traditional heritage, biocultural phenomena, or other notices of significance directly to the end-user. In a pilot project, ONC will develop the software architecture to support Local Context labelling. Using guiding documents and best practices, ONC will implement this in our underlying metadata profiles such DataCite Fabrica and ISO19115. Further software development will make labels visible in our Dataset Landing Pages (DOIs). The labels will be inherited directly from the Local Contexts application programming interface (API) of projects associated with our Indigenous partner communities. Since there are currently no partner communities using Local Contexts, ONC will also design a “mock community” with ONC-owned data to provide tangible examples of Local Contexts dataset integration to our partners and the broader scientific community. Should the pilot project be deemed successful, ONC will then fully implement Local Contexts compatibility with our production version of ONC’s Oceans 3.0 Data Portal. Communities ONC engages with will then have the option to utilize Local Contexts to further their own Indigenous data governance and sovereignty.

A document by Dani Jones. Click on the document to view its contents.

A document by Josh. Click on the document to view its contents.

Solar eruptive phenomena result in irregular processes in solar wind plasma and interplanetary magnetic field. Most high-speed streams, interplanetary shock waves, and other irregularities propagate to the heliosphere's edge non-independently from each other. One such mutual impact is the effective acceleration of charged particles at fronts of shock waves driven by the Coronal Mass Ejections (CMEs). In our study, we review a few fast-forward shock waves that affected differently the spectra, intensities, and species of energetic particles in the interplanetary space from January to May 2023. IP shocks were identified based on data from the Proton Alpha Sensor (PAS) of the Solar WindAnalyzer (SWA) and the Magnetometer (MAG). Simultaneously, we analyze some specific features in the effectivity of the charged particle acceleration for some selected phenomena mentioned using data and spectrograms of energetic particles observed by the Electron Proton Telescope (EPT), the SupraThermal Electrons and Protons (STEP), and the SupraThermal IonSpectrograph (SIS), of the EPD suite. We demonstrate that shock waves are not the only objects that influence the peculiarities in parameters of energetic particles in the heliosphere. The magnetic flux ropes, wave foreshocks, short- and long-duration magnetic holes, and other plasma structures should be considered from the point of view of affecting the spectral, temporal, and spatial parameters of energetic particles.This work is supported by the “Long-term program of support of the Ukrainian research teams at the Polish Academy of Sciences carried out in collaboration with the U.S. National Academy of Sciences with the financial support of external partners”.

The equatorial cold tongue region has not warmed up in response to historical radiative forcing in the real world, contrary to the strong warming often simulated by climate models. Here we demonstrate that climate models fail to represent one or both of the key processes driving observed sea surface temperature (SST) pattern formation: a realistic surface wind stress pattern shaping subsurface cooling through wind-driven circulation changes, and effective connectivity between subsurface and surface temperatures via upwelling and mixing. Consequently, none of the models approximate the observed lack of cold tongue SST warming and strengthening of zonal SST gradient across the equatorial Pacific. Further, those that come closest achieve this due to interhemispheric warming differences rather than equatorial dynamics as observed. Addressing different origins of subsurface cooling in observations and simulations, and how they connect to SST, will lead to improved understanding of tropical Pacific SST changes to date and how they will evolve in the future.

Sediment-rich mélange diapirs have been suggested to transport key chemical slab signatures and volatiles to arc magma sources. Here, we assess the phase equilibria, buoyancy and implications for chemical geodynamics of a previously unexplored hydrous shaly-rich mélange (5-10 wt.% H2O) with minor ultramafic component (9:1 ratio) from deep forearc to subarc depths (2-3 GPa and 700-1150°C). Their solidi lie between <645 to ~700°C and upon partial melting, produce dacitic to rhyolitic melts (water-free basis) in coexistence with abundant biotite, pargasitic-amphibole, and quartz (low dense minerals), garnet, and enstatite (rutile/Ti-magnetite ± apatite) that favors the onset of diapirs in thinner mélange channels (<100m) with lower mélange and mantle viscosities in all slab geotherms. At >850°C the low dense mineral abundance decreases, and the mélange loses buoyancy, requiring thicker mélange channels (>100-800m) with higher mélange and mantle viscosities. Thinner and thicker mélanges form smaller (<1 km radius) and larger diapirs (>1 km radius), respectively. While smaller are more susceptible to mineralogical equilibration, lose buoyancy and stall, larger diapirs may sustain buoyancy and relaminate under the arc crust. High LILE/HFSE signatures in most arc lavas may be explained by aqueous fluids and low degree mélange partial melting (<850°C) within the channel or a diapir close to the channel where rutile/apatite/Ti-Fe-oxides minerals are stable, and the presence of garnet impart high LILE/HREE. Although high degree partial melts due to diapirism or slab tears explain dacitic to rhyolitic arc lavas, they would not fractionate HFSEs from LILEs to explain the high HFSE/LILE arc lava signature.

We investigate whether or not the default ocean-atmosphere turbulent flux algorithm in the Energy Exascale Earth System Model version 2 (E3SMv2) converges to unique surface fluxes. We demonstrate that under certain conditions (i) discontinuities in the underlying equations result in the lack of a solution for the algorithm to converge to, and (ii) more than one set of surface fluxes may satisfy the aforementioned equations, some of which may have non-physical interpretation. These issues underpinning the theoretical foundations of the parameterization have significant impacts on the accuracy and convergence of turbulent fluxes in E3SM.   We address issues of non-existence and non-uniqueness of surface fluxes in E3SM’s default algorithm by (a) regularizing discontinuous exchange coefficients to enforce continuity and allow the algorithm to converge to a solution of the underlying equations, and (b) utilizing an adaptive procedure for selecting limiting values of the Monin-Obukhov length to ensure the underlying equations have a unique solution. The proposed revisions result in significant changes to model latent and sensible heat fluxes which are most notable in boreal winter in the Northern Hemisphere.

Glacier mass loss is one of the main contributors to sea-level rise and poses challenges for future water resources. Refining glacier projections and sources of uncertainty thus supports climate adaptation and mitigation. Here we explicitly quantify the impact of internal climate variability and climate data bias adjustment methods on regional and global glacier projections through 2100 for various emissions scenarios. Uncertainty from internal climate variability is comparable to climate model structural uncertainty in the coming decades at the regional level, but is not a major source of uncertainty in centennial global glacier projections. Bias adjustment options (method and time period) greatly impact projections at regional and glacier scales, but have a smaller impact (~4% of global glacier mass at 2100, relative to 2020) at global scales. In some regions, internal climate variability is larger than climate model structural uncertainty for the entirety of the 21st century, and bias adjustment options can more than double the regional uncertainty by 2100. At the glacier scale, bias adjustments can lead to differences in projected decadal and centennial mass loss of up to 50%, although these greatest differences are associated with the smallest (<1 km2) glaciers. Overall, internal climate variability and climate data bias adjustment methods are important to consider, especially in regional applications, to better estimate uncertainty in future sea-level rise and water resources availability.

Most published shear-wave (VS) velocity models of cratons include a VS increase with depth below the Moho, with a maximum at 100-150 km depth. This feature is seen in regional and global 3D tomography models and in regional 1D VS profiles. Taken at face value, it implies an oscillatory geotherm, with a ubiquitous temperature decrease below the Moho, which is implausible. The VS increase with depth has thus been attributed to strong compositional layering in the lithosphere. One recent model postulated widespread hydration and metasomatism in the uppermost cratonic mantle, decreasing VS just below the Moho. An alternative model suggested a strong enrichment of the lower cratonic lithosphere in eclogite and diamond, increasing VS but implying an unusual lithospheric composition. Here, we assemble a representative dataset of phase-velocity curves of Rayleigh and Love surface waves for cratons globally, including the all-craton averages, averages over regions in southern Africa, and interstation measurements elsewhere. We perform both thermodynamic and purely seismic inversions and show that the sub-Moho VS increase is not required by the data. Models with equilibrium, conductive lithospheric geotherms and ordinary, depleted-peridotite compositions fit the surface-wave data fully. A model-space mapping quantifies the strong trade-off between seismic velocities just below the Moho and at 100-150 km depth, which is the cause of the ambiguity. The reason why most seismic models contain a VS increase with depth below the Moho is regularization that penalizes deviations from global average reference models, which are much slower than cratonic VS profiles.