This study showcases a global, heterogeneously coupled total water level system wherein salinity and temperature outputs from a coarse-resolution ($\sim$12 km) ocean general circulation model are used to calculate density-driven terms within a global, high-resolution ($\sim$2.5 km) depth-averaged total water level model. We demonstrate that the inclusion of baroclinic forcing in the barotropic model requires careful treatment of the internal wave drag term in order to maintain the fidelity of tidal results from the purely barotropic model. By accurately capturing the internal tide dissipation within the coupled system, the resulting heterogeneously coupled model has deep-ocean tidal errors of 2.27 cm, outperforming global, depth-resolving ocean models in representing global tides. Moreover, global median root mean square errors as compared to observations of total water levels, 30-day sea levels, and non-tidal residuals improve by 1.86, 2.55, and 0.36 cm respectively. The drastic improvement in model performance highlights the importance of including density-driven effects within global hydrodynamic models and will help to improve the results of both hindcasts and forecasts in modeling extreme and nuisance flooding. With only an 11\% increase in computational time as compared to the fully barotropic total water level model, this efficient approach paves the way for high resolution coastal water level and flood models to be used directly alongside climate models, improving operational forecasting of total water levels.

Due to their limited resolution, numerical ocean models need to be interpreted as representing filtered or averaged equations. How to interpret models in terms of formally averaged equations, however, is not always clear, particularly in the case of hybrid or generalized vertical coordinate models. We derive the averaged hydrostatic Boussinesq equations in generalized vertical coordinates for an arbitrary thickness weighted-average. We then consider various special cases and discuss the extent to which the averaged equations are consistent with existing model formulations. As previously discussed, the momentum equations in existing depth-coordinate models are best interpreted as representing Eulerian averages (i.e., averages taken at fixed depth), while the tracer equations can be interpreted as either Eulerian or thickness-weighted isopycnal averages. Instead we find that no averaging is fully consistent with existing formulations of the parameterizations in semi-Lagrangian discretizations of generalized vertical coordinate ocean models. Perhaps the most natural interpretation of generalized vertical coordinate models is to assume that the average follows the model’s coordinate surfaces. However, the existing model formulations are generally not consistent with coordinate-following averages, which would require “coordinate-aware” parameterizations that can account for the changing nature of the eddy terms as the coordinate changes. Alternatively, the model variables can be interpreted as representing either Eulerian or (thickness-weighted) isopycnal averages, independent of the model coordinate that is being used for the numerical discretization. Existing parameterizations in generalized vertical coordinate models, however, are usually not fully consistent with either of these interpretations. We discuss what changes are needed to achieve consistency.

A document by Dion Jia Xu Ho. Click on the document to view its contents.

Implicit time-stepping for advection is applied locally in space and time where Courant numbers are large, but standard explicit time-stepping is used for the remaining solution which is typically the majority. This adaptively implicit advection scheme facilitates efficient and robust integrations with long time-steps while having negligible impact on the overall accuracy, and achieving monotonicity and local conservation on general meshes. A novel and important aspect for the efficiency of the approach is that only one linear solver iteration is needed for each advection solve. The implementation in this paper uses a second-order Runge-Kutta implicit/explicit time-stepping in combination with a second/third-order finite volume spatial discretisation. We demonstrate the adaptively implicit advection in the context of deformational flow advection on the sphere and a fully compressible model for atmospheric flows. Tracers are advected over the poles of latitude-longitude grids with very large Courant numbers and through hexagonal and cubed-sphere meshes with the same algorithm. Buoyant flow simulations with strong local updrafts also benefit from adaptively implicit advection. Stably stratified flow simulations require a stable combination of implicit treatment of gravity and acoustic waves as well as advection in order to achieve long stable time-steps.

Flood insurance is an important financial measure for flood risk management. However, a significant protection gap in flood insurance exists in many countries due to high flood insurance costs. Reducing flood insurance costs for both policyholders and insurance companies is crucial for implementing flood insurance. In this study, we derive fundamental mathematical principles for reducing overall insurance costs, including premiums and risk reserves, by introducing the geographic complementarity of flood risk based on portfolio theory. We also propose a reasonable premium allocation framework among multiple individual policyholders using cooperative game theory (CGT), which can benefit all policyholders and achieve stable allocation. The proposed approach is illustrated using China as a case study. The results show that there are low correlation coefficients of flood losses across different provinces and river basins in China, showing high geographic risk complementarity. Compared to independent insurance in each province, national flood insurance can reduce total premiums by 14.8% and total risk reserves by 60.8%. The Yangtze River Basin shows the greatest premium reduction by pooling its internal flood risk, compared with independent insurance by provinces. The Yellow and Huai River Basin shows the greatest premium reduction when pooling national flood risk, compared with pooling risk within individual river basins. In summary, geographic complementarity in flood risk has significant effects on reducing flood insurance costs, implying that China can employ this characteristic to implement a national flood insurance program. Furthermore, the proposed approach can also offer new insights for enhancing catastrophe insurance affordability in more countries.

As a net water production entity where unconventional oil and gas extraction operations generate volumes of hypersaline water (known as produced water, PW) greater than they consume, it is imperative to consider what options are available for this new source of water to displace water demand on the nations already struggling water supplies. The increased awareness of the adverse environmental impacts associated with underground injection is expected to drive PW management away from underground disposal. Meanwhile, the lack of data on the chemical constituents and the toxicological characteristics of treated PW has likely hampered regulatory agencies in developing policies that enable advanced PW treatment for reuse. Therefore, until a PW reuse market emerges to justify the costs of advanced treatment, the most viable PW management strategy for operators is to reduce the volume of PW for disposal. This study examines the cost and environmental benefits of adopting on-site thermal evaporation process through data collected from multiple developmental basins – the Rockies, Appalachia, and Haynesville basins using thermal evaporators. We developed a method for assessing the cost benefit and applied to a hypothetical scenario for Eagle Ford shale to demonstrate the potential benefits of thermal evaporation. The challenges and limitations are also discussed in this paper.

Martian layered ejecta craters are theorized to form by tapping into water ice. The inference that some equatorial layered ejecta craters are Amazonian indicates ice has persisted in the tropics. However, detailed spatial and temporal distribution and evolution of this ice remains unknown; which is critical to constraining Mars’ global water cycle and climate change over eons. Here we estimate absolute model formation ages for layered and radial (ballistic) ejecta craters to constrain the spatial and temporal distribution of equatorial ice. The assumption is radial ejecta form where volatiles are not present in significant quantities. Ages are derived from the density of smaller craters superposed on the ejecta blankets. We examine 73 craters in a 30° x 30° area centered at 15ºS, 355ºE, with 44 layered and 29 radial ejecta. Analysis suggests an increasing proportion of layered ejecta craters with increasing diameter. This trend is amplified when considering younger (<3.4 Ga) craters only andwould be in agreement with deeper tropical subsurface ice and a receding ice table. Conversely, it could indicate “armoring” preserves layered over radial ejecta. Layered and radial ejecta craters are mixed over distances comparable to their diameters, which represents an unreasonably short length scale for ground-ice emplacement. This supports intermittent low-latitude surface ice—from excursions to high obliquity—could be responsible. The combination of increasing proportion of layered ejecta with crater size and random spatial distribution may suggest a hybrid model in which buried ice and intermittent, but extensive, tropical glaciers both contribute to layered ejecta crater formation.

A document by Kevin T. Trinh. Click on the document to view its contents.

Van Allen radiation belt electron dynamics are governed by a wide range of physical processes that can simultaneously drive acceleration, transport and loss. However, each individual process can be linked to a specific energy-dependent pitch angle distribution (PAD). We employ a new, unsupervised machine learning technique on 7-years of Van Allen Probe Relativistic Electron-Proton Telescope data and discover that six PADs, two each of: pancake, butterfly, and flattop, successfully describe >70% of classified relativistic PADs. We investigate the occurrence and storm-time evolution of each PAD through 45 geomagnetic storms. We find new populations of PADs, including: “shadowing-like” and wave-particle interaction signatures at low-L, and radial diffusion and substorm injections at higher-L, as well as determining that wave-particle interaction dominated PADs are swamped by radial diffusion processes through geomagnetic storms. Our results clearly demonstrate that PAD characterisation is a key component of understanding Van Allen radiation belt electron dynamics

An unusual salt-rich (SR) and salt-poor (SP) fluid immiscibility (FFI) could occur in a variety of hydrothermal fluids. The segregation of SR fluid from SP fluid provides a potential mechanism for substantial mass enrichment during some ore forming processes. However, the physical properties of SR and SP fluids, which determine the hydrodynamic behaviors of unmixed fluids, have not been well constrained. This study adopted in situ optical observation, quantitative Raman analysis, and the mass conservation law to derive the density of the SR and SP fluids. On this basis, falling sphere viscometry was employed to determine the viscosity of the SR fluid. Results showed that SR fluid exhibited an obviously higher density but comparable viscosity to SP fluid, favoring its high mobility and strong tendency to segregate from SP fluid. Consequently, the FFI could contribute tremendously to mass enrichment during fluid evolution.

Zinc (Zn) is biogeochemically significant due to its crucial role in biological processes. In the global ocean, there is an apparent coupling between the concentrations of zinc and silicon (Si), and there is a consistent ratio between the two. However, this coupling is observed to be disrupted in the North Pacific Ocean. It has been suggested that this disruption is due to Zn that originates on the continental shelf. However, this explanation relied on the particular circulation field used in the model described in the relevant study. The aim of the current study was to use more realistic circulation fields as the basis of a more accurate evaluation of deep circulation and export production in the North Pacific. We also aimed to analyze the impact of uptake parameters, continental-shelf supply, and regeneration of Zn on the observed Zn–Si decoupling in the North Pacific. Sensitivity experiments employing two distinct circulation fields were performed. It was found that the two circulation fields yielded different decoupling influences: continental-shelf supply or regeneration. A comparison between the two circulation fields also revealed discrepancies in the concentration of regenerated Zn. The main factors causing these differences were found to be the age of the water masses in the North Pacific and the magnitude of export production. Greater export production and a more stagnant circulation field in the North Pacific led to more regenerated Zn and a higher probability of decoupling without the need for an input of Zn from the continental shelf.

 We have characterized the magnitude and spatial extent of observed regional and inter-regional air temperature trends and warming extremes across Antarctica. Prior studies have used localized observational records to analyze air temperature trends across distinct geographical regions, leaving local and inter-regional variations to be undetected. Using the high-resolution temperature product AntAir ICE, air temperature trends and extreme warming events during austral summers were identified across Antarctica for the period 2003-2021. Unsupervised clustering was applied to austral summer and annual mean air temperature trends to divide Antarctica into 12 regions exhibiting similarity in temperature trends. Our results show a significant annual mean cooling trend of - 0.12 °C/Yr for the terrestrial Antarctic Peninsula, and an austral summer (annual) warming trend of + 0.08°C/Yr (+0.07 °C/Yr) in the Ross Sea region’s Victoria Land and Transantarctic Mountains. The spatial extent of each of the 12 clusters’ extreme air temperature events was mapped revealing that West Antarctica has spatially confined events, while East Antarctica events are widespread. ERA5 data indicates that West Antarctica's extreme air temperature events are associated with consistent meridional atmospheric flows. Local to regional extreme warming events in East Antarctica are associated with inland high-pressure systems, which enhance katabatic winds. Localized warming events around complex coastal geographies were detected and appear to be related to mesoscale wind systems such as foehn but require further investigation using mesoscale numerical weather models. This work highlights the necessity for ongoing and new monitoring in regions where critical ecological and physical thresholds are being surpassed.

Waves, rivers, and tides shape delta morphology. Recent studies have enabled predictions of their relative influence on deltas globally, but methods and associated uncertainties have remained poorly known. We address that gap and expand on earlier work that quantified delta morphology within the Galloway ternary diagram of river, wave, and tidal sediment fluxes. We assess delta morphology predictions compared to observations for 31 deltas globally and find a median error of 4% (standard deviation of 11%) in the river, tide, or wave-driven sediment fluxes. Relative uncertainties are greatest for mixed-process deltas (e.g., Sinu, error of 49%) and tend to decrease for end-member morphologies where either wave, tide, or river sediment fluxes dominate (e.g., Fly, error of 0.2%). Prediction uncertainties for delta morphologic metrics are more considerable: the delta shoreline protrusion angles set by wave influence have a median error of 45%, the delta channel widening from tides 25%, and the number of distributary channels 86%. Larger sources of prediction uncertainty are (1) delta morphology data, e.g., delta slopes that modulate tidal fluxes, (2) data on river sediment flux distribution between individual delta river outlets, and (3) theoretical basis behind fluvial and tidal dominance. Future works should address these sources, improving predictions of delta morphology from sediment fluxes that allow us to assess how much climate and global changes affect deltas.

While the service industry is generally considered a low-carbon sector, it contributes significantly to global carbon emissions. However, such emissions have typically relied on production-based evaluations without accounting for emissions embodied in international trade. Here, this paper estimates the consumption-based emissions (CBE) of the service industry and investigates the flows of embodied emissions globally using a Multi-regional Input-output model. Structural path analysis (SPA) and decomposition (SPD) methods are used to explore emission reduction paths and the driving factors. Our results show that the CBE of the global service industry not only increased by 63% but now comprised approximately over 30% of global total emissions, with the public and welfare services, health services sectors contributing the most to emissions growth. The consumption-based carbon intensity of the global service industry declined markedly, or nearly one-quarter of global carbon intensity. Advanced countries such as Japan, the UK, and the USA, were identified as the leading net importers of embodied service industry emissions, with air transport and water transport being the primary sources of carbon inflow. Russia was the principal net exporter of emissions. China altered from a net exporter of emissions to a net importer. The results reveal that the second layer had a more pronounced influence on the emissions than other layers, although the contribution of higher layers to emissions steadily increased. Emission intensity effect promoted emissions declines, while the increasing consumption level restrained such decreases. This study aims to provide valuable insights into reducing the emissions of the global service industry.

A novel Python module called PyIRTAM was developed in addition to the previously released PyIRI model. The PyIRI computational approach was extended to work with Real-Time Assimilative Model (IRTAM) coefficients. This enables global approach to the density specification, utilizing computation of the global and diurnal functions and their multiplication with coefficients in the matrix form. PyIRTAM tool is made publicly available through PyPI and GitHub.

We present the first global geospace simulation to reproduce auroral giant undulations (GUs). To identify their magnetospheric drivers, we employ the MAGE (Multiscale Atmosphere-Geospace Environment) model in a case study of a geomagnetic storm for which there were spacecraft- and ground-based observations of GUs. The model reproduces the spatial and temporal scales of the GUs as well as the presence of duskside subauroral polarization streams (SAPS) and plasmapause undulations. Based on our modeling, we are able to identify the magnetospheric drivers of GUs as mesoscale ring current injections which, after drifting westward, create inverted regions of flux-tube entropy (FTE) and subsequent interchange instability. Outward-protruding interchange fingers disrupt shielding of the inner magnetosphere, creating longitudinally-localized ripples in magnetospheric convection equatorward of the magnetospheric instability, which structure the plasmapause and duskside diffuse precipitation. While not causal, SAPS and plasmapause undulations are a consequence of the unstable magnetospheric configuration.

The soil water retention curve (SWRC) is essential for describing water and energy exchange processes at the interface between the solid earth and the atmosphere. Despite its importance, measuring the SWRC using standard laboratory methods is challenging and time-consuming. This paper presents a novel physics-informed neural network (PINN) approach for developing pedotransfer functions (PTFs) to predict continuous SWRCs based on soil texture, organic carbon content, and dry bulk density. In contrast to conventional parametric PTFs developed for specific SWRC models, the PINN learns a non-specific form of the SWRC by effectively integrating both measurements and physical constraints into the training process. This approach allows the estimated SWRC to maintain its physical integrity from saturation to oven-dry conditions, even in scenarios with sparse data. The new approach is particularly effective for tackling the challenges encountered in developing PTFs on large SWRC datasets, which often have an imbalance towards the wet-end and include numerous samples with limited and unevenly distributed measurements. We compared the performance of the PINN with that of a conventional physics-agnostic neural network using a dataset of 4200 soil samples. While both networks performed similarly at the wet-end where data are abundant, the PINN excelled at the dry-end where data are sparse and unevenly distributed, achieving a normalized RMSE of 0.172 compared to 0.522 for the conventional neural network. The SWRC derived from the PINN is differentiable with respect to the matric potential and can be seamlessly integrated into the governing equations of water flow in the unsaturated zone.

After days of intense solar activity, active region AR3664 launched seven CMEs towards Earth producing an extreme G5 geomagnetic storm commencing at 16:45 UT on Saturday May 10, 2024. The storm impacted power grids, disrupted precision navigational systems used by farming equipment, and generated aurora seen around the globe. The storm produced remarkable effects on composition, temperature, and dynamics in the Earth’s thermosphere that were observed by NASA’s Global-scale Observations of the Limb and Disk (GOLD) mission and are reported here for the first time. We use synoptic disk images of ΣO/N2 and neutral temperature (at ~160 km) measured by GOLD to directly link dynamics resulting from the storm with dramatic changes in thermospheric composition and temperature. We observe an apparent rotation simultaneously in ΣO/N2, neutral temperature, and total electron content. Equator-to-pole temperature differences reach 400 K with peak neutral temperatures near 160 km exceeding 1400 K at high latitudes.