New bioavailable nitrogen (N) from biological nitrogen fixation (BNF) is critical for the N budget and productivity of marine ecosystems. Nitrogen-fixing organisms typically inactivate BNF when less metabolically costly N sources, like ammonium (NH4+), are available. Yet, several studies observed BNF in benthic marine sediments linked to anaerobic sulfate-reducing bacteria (SRB) and fermenting firmicutes despite high porewater NH4+;concentrations (10-1,500 μM), making the importance of and regulating controls on benthic BNF unclear. Here, we evaluate BNF sensitivity to NH4+ in model anaerobic diazotrophs, the sulfate-reducer Desulfovibrio vulgaris var. Hildenborough and fermenter Clostridium pasteurianum strain W5; in sulfate-reducing sediment enrichment cultures, and in sediment slurry incubations from three Northeastern salt marshes (USA). BNF in sulfate-reducing cultures and sediments is highly sensitive to external NH4+, with a threshold for BNF inhibition of [NH4+] < 2 μM in cultures and < 9 μM in sediment slurries. The prevalence of SRB-like sequences in sediment-derived nitrogenase (nifH) genes and transcripts in this and other studies of benthic BNF along with an analysis of benthic NH4+ porewater data suggests a broad applicability of the inhibition thresholds measured here and the confinement of benthic BNF to surficial sediments. The timing of inhibition, fast NH4+ drawdown, and sediment heterogeneity are factors that can complicate studies of benthic BNF sensitivity to NH4+. We propose a simple theoretical framework based on the affinity of the NH4+ transporter to explain NH4+ control of BNF and improve biogeochemical models of N cycling.

Hilal ERDOGAN1*, Pelin OZMEN 2, Hayrun Nisa BULBUL31 Nevsehir Haci Bektas Veli University, Faculty of Dentistry, Department of Endodontics, Nevsehir, Turkiye. ORCID: 0000-0001-5219-46932 Nevsehir Haci Bektas Veli University, Faculty of Dentistry, Department of Basic Sciences, Department of Medical Microbiology, Nevsehir, Turkiye. ORCID: 0000-0001-9496-30323 Nevsehir Haci Bektas Veli University, Institute of Science and Technology, Department of Molecular Biology and Genetics, Nevsehir, Turkiye. ORCID: 0000-0001-6843-417x* Corresponding authorCorrespondence author: Hilal ERDOGANNevsehir Haci Bektas Veli University, Faculty of Dentistry, Department of Endodontics, 2000 Evler Mah. Zübeyde Hanım Cad. 50300, Nevşehir/Turkiye. Email:[email protected]: +90 (384) 228 10 00-22009ORCID ID: 0000-0001-5219-4693Acknowledgments: The authors deny any conflicts of interestFunding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.All authors have contributed significantly, and all authors are in agreement with the manuscript.

Midstream oil and gas infrastructure comprises vast networks of gathering and transmission pipelines that connect upstream extraction sites to downstream processors, exporters, and consumers. In the United States (US), public policies and corporate decisions continue to promote the extraction and consumption of oil and gas, and they have prompted a wave of proposals for gathering and transmission pipelines in recent years. The ongoing build-out of midstream infrastructure calls for close scrutiny of associated human health risks and related societal impacts. Urgency is warranted considering that at least part of this infrastructure, the US natural gas pipeline network, is concentrated more heavily in areas of high social vulnerability than areas of low social vulnerability, highlighting inequity in the distribution of societal harms. Emerging research on ways in which midstream pipelines affect Indigenous peoples and rural communities in the US demonstrates the complex nature of potential harms. The spatial distribution of midstream infrastructure, together with the complexity of societal impacts underscore the need to clearly understand and carefully consider these impacts during infrastructure planning and permitting. We offer recommendations for scientists and decision-makers who are interested in evaluating these impacts through the lens of environmental justice.

Computational geoscience courses often combine domain science, math, programming, and hardware instrumentation. Ensuring students master all those skills can be daunting for professors, as well as for students who tackle these hybrid classes. Through a series of 3-day in-person workshops, faculty across the geoscience disciplines and allied science fields have collaborated to produce on-line teaching resources and a community of peers to support these multi-faceted but essential Geoscience courses. These resources support Geoscience and Science educators seeking to update their curriculum and even create whole new courses. Topics addressed include approaches to teaching, best practices for working group design, empowering students to self-advocate, building computational skills optimally, and coordinating curriculum across a department and even cross-departments. This e-lightning talk will show the resources available to educators – teaching activities including MATLAB code, presentations on teaching approaches, and course curriculum, among others. It will also highlight relevant MathWorks tools for learning and teaching, from online videos, to free, interactive MATLAB tutorials (MATLAB Onramp and more), to autograding software for MATLAB code (MATLAB Grader), with associated publicly available homework problem sets. Attendees will learn where and how to access these online resources, share their teaching challenges, and participate in future workshops.

Ocean color satellites require routine in-orbit verification and vicarious calibration to maintain accuracy over the mission lifetime and between satellites. The majority of vicarious calibration and validation activities for ocean color satellites are carried out in areas of uniform oceanic and atmospheric optical properties using in situ radiometric data collected from fixed mooring installations or oceanographic ships. These methods have limitations in spatial coverage and in the cost of maintenance and operation. A spatially extensive network of vicarious calibration match-up data points would aid in reducing vicarious calibration uncertainty. To meet these needs, we have developed a new approach to ocean color satellite vicarious calibration and validation. Our system (HYPERNAV) combines accurate, reliable and stable hyperspectral radiometric instruments with autonomous profiling float technologies to provide a cost effective, unattended means for vicarious calibration over periods of years in the open ocean. We present data from laboratory and field experiments of the HYPERNAV system used to characterize system performance and to quantify the end-to-end radiance uncertainty budget. We present match-up comparisons of HYPERNAV field data and coincident water leaving radiance measurements from ocean color satellites, demonstrating the capabilities of the system to provide new vicarious calibration paradigm for ocean-color remote-sensing satellites.

A document by Rowan Alethea Dayton-Oxland. Click on the document to view its contents.

In 2015, Integrated Ocean Discovery Program Expedition 356 drilled along the margin off Western Australian to investigate the history of the Indonesian Throughflow (ITF) and its integral role in the development of global thermohaline circulation and climate. Throughout the expedition, a suite of foraminiferal analyses were employed wherein planktic specimens provided biostratigraphy and an incredibly diverse benthic fauna (~ 260 species) was used to reveal palaeo- water depth, palaeobathymetric setting and variable conditions at the sediment-water interface. Benthic foraminiferal biofacies are particularly sensitive to changes in environmental conditions, have a rapid turnover and are ideal proxies for monitoring physical and chemical changes in marine environments. When this information is combined with lithostratigraphic and other microfossil data, a robust understanding of past environments and past geological events can be reconstructed. Shipboard data were used to isolate horizons of interest for more intense sampling at IODP Site U1461, situated on the North-West Shelf, at 127 m of water depth. The shipboard data revealed a large (~150 m-thick) turbidite horizon hosting benthic foraminifera from a substantially shallower water depth than the horizon immediately preceding the horizon. We present preliminary foraminiferal results combined with shipboard sedimentary descriptions to better constrain the deposit’s occurrence in the biostratigraphic record, use benthic foraminifera to elucidate the deposit’s sedimentary origins and link this event with others in the region to investigate potential catalysts for its deposition.

Connecting the sources of reactive nitrogen (Nr) emissions to downstream environmental impacts is challenging, since Nr “cascades” through sequential ecosystems. It is therefore important to examine a jurisdiction’s overall Nr emissions to gain perspective on whether total levels and specific forms of Nr emissions are being reduced. We study subnational (provincial) trends and variations in Nr emissions in Canada over 30 years (1990-2017) to examine the effects of key policy, socioeconomic, and technological changes on Nr emissions. We use data from national Nr emissions inventories, agricultural nutrient models, and wastewater treatment reports to estimate specific (N2O, NOx, NH3, and NO3), total (Gg N) and per capita (Kg N / capita) Nr emissions by province. We divide the initial sources of Nr emissions into 1) agricultural-related emissions, 2) fossil-fuel emissions, and 3) waste management emissions. Preliminary results show that annual total Nr emissions in Canada increased between 1990-2000 (1250 Gg to 1490 Gg), and have since decreased (to 1180 Gg). There was a redistribution of the main species of Nr, with decreases of NOx from fossil fuels (from 660 to 488 Gg Nr / year) and increases in agricultural Nr emissions (from 452 Gg to 537 Gg Nr / year). Provincial trends vary. Overall NOx emissions decreased across all provinces due to more stringent vehicle regulations, except in Alberta, where NOx emissions from export-oriented oil production increased. The increase in national agricultural emissions comes primarily from Saskatchewan whose combined agricultural emissions increased from 43 Gg to 97 Gg Nr year. Improving agricultural nitrogen-use efficiency, especially in these provinces, would be a key area for reducing Canada’s Nr emissions. However, given that diesel and gasoline vehicles still contribute 121 Gg Nr / year, electrifying vehicle fleets would also have considerable potential for reducing Nr emissions. Our study demonstrates the variation in and reconfiguration of drivers of Nr emissions at the sub-national scale in Canada, emphasizing the need to consider local contexts and relative contributions of different economic sectors when examining national Nr emissions.

Seawater intrusion (SI) poses a substantial threat to water security in coastal regions, where numerical models play a pivotal role in supporting groundwater management and protection. However, the inherent heterogeneity of coastal aquifers introduces significant uncertainties into SI predictions, potentially diminishing their effectiveness in management decisions. Data assimilation (DA) offers a solution by integrating various types of observational data with the model to characterize heterogeneous coastal aquifers. Traditional DA techniques, like ensemble smoother using the Kalman formula (ESK) and Markov chain Monte Carlo, face challenges when confronted with the non-linearity, non-Gaussianity, and high-dimensionality issues commonly encountered in aquifer characterization. In this study, we introduce a novel DA approach rooted in deep learning (DL), referred to as ESDL, aimed at effectively characterizing coastal aquifers with varying levels of heterogeneity. We systematically investigate a range of factors that impact the performance of ESDL, including the number and types of observations, the degree of aquifer heterogeneity, the structure and training options of the DL models. Our findings reveal that ESDL excels in characterizing heterogeneous aquifers under non-linear and non-Gaussian conditions. Comparison between ESDL and ESK under different experimentation settings underscores the robustness of ESDL. Conversely, in certain scenarios, ESK displays noticeable biases in the characterization results, especially when measurement data from non-linear and discontinuous processes are used. To optimize the efficacy of ESDL, attention must be given to the design of the DL model and the selection of observational data, which are crucial to ensure the universal applicability of this DA method.

We present multi-instrument Juno observations on day-of-year 86, 2017 that link particles and fields in Jupiter’s polar magnetosphere to transient UV emissions in Jupiter’s northern auroral region known as dawn storms. Juno ranged from 42ºN - 51ºN in magnetic latitude and 5.8 – 7.8 jovian radii (1 RJ = 71,492 km) during this period. These dawn storm emissions consisted of two separate, elongated structures which extended into the nightside, rotated with the planet, had enhanced brightness (up to at least 1.4 megaRayleigh) and high color ratios. The color ratio is a proxy for the atmospheric penetration depth and therefore the energy of the electrons that produce the UV emissions. Juno observed electrons and ions on magnetic field lines mapping to these emissions. The electrons were primarily field-aligned, bi-directional, and, at times, exhibited sudden intensity decreases below ~10 keV coincident with intensity enhancements up to energies of ~1000 keV, consistent with the high color ratio observations. The more energetic electron distributions had characteristic energies of ~160 – 280 keV and downward energy fluxes (~70 – 135 mW/m2) that were a significant fraction needed to produce the UV emissions for this event. Magnetic field perturbations up to ~0.7% of the local magnetic field showing evidence of upward and downward field-aligned currents, whistler mode waves, and broadband kilometric radio emissions were also observed along Juno’s trajectory during this timeframe. These high latitude observations show similarities to those in the equatorial magnetosphere associated with dynamics processes such as interchange events, plasma injections, and/or tail reconnection.

Building design codes recommend using nonlinear dynamic analysis for an appropriate assessment of the seismic response of several types of structures. To perform nonlinear dynamic analysis, the recorded ground motion time histories of past events with a certain seismic intensity level compatible with the regional seismological characteristic are usually scarce. Therefore, alternative selection and scaling methods on the previously recorded ground motion data set are commonly employed to overcome this issue. However, the type of method and also the random characteristics of earthquake ground motion data induce variability in the estimation of structural response. In this paper, the effect of code-based ground motion selection approaches is investigated in predicting the seismic demand of masonry structures. The dynamic behavior of the masonry prototype is simulated through a 3D numerical model. The material non-linearities are taken into account by adopting a proper constitute law. The data set of PEER is used as the pool for selection and scaling based on alternative codes, including American standard and Eurocode. Results showed that alternative code-based selection approaches reach various seismic demand levels. Keywords: Ground motion records, PEER data set, Scaling, Code-based selection, Masonry structures, Incremental dynamic analysis

Tropical Instability Vortices (TIVs) have a major influence on the physics and biogeochemistry of the equatorial Pacific. Using an eddy-resolving configuration of the Community Earth System Model (CESM-HR) and Lagrangian particle tracking, we examine TIV impacts on the three-dimensional structure and variability of dissolved oxygen (O2) in the upper equatorial Pacific water column. In CESM-HR, the simulated generation and westward propagation of TIVs from boreal summer through winter lead to the seasonal oxygenation of the upper northern equatorial Pacific, exhibited as a deepening of hypoxic depth west of 120ºW. TIV effects on the equatorial Pacific oxygen balance are dominated by eddy-advection and mixing, while indirect TIV effects on O2 consumption play minor roles. These advective effects reflect the transient displacements of isopycnals by eddy pumping as well as vortex transport of oxygen by eddy trapping, stirring, and subduction. TIVs influence on the upper equatorial Pacific O2 distribution and variability has important implications for understanding and modeling marine ecosystem dynamics and habitats, and should be taken into consideration in designing observation networks in this region.

Polar Cap PC) indices, PCN North based on magnetic observations from Qaanaaq (THL) in Greenland and PCS South based on magnetic data from Vostok in Antarctica, are very useful indices for studies of solar wind-magnetosphere interactions and for space weather monitoring and forecasts. PCN indices are issued from the Danish Space Research Institute (DTU Space) while PCS indices are issued from the Arctic and Antarctic Research Institute (AARI) in St Petersburg. Unfortunately, series of invalid PCS values have been provided from AARI and used in a number of publications issued since the PC index concept was endorsed by the International Association of Geomagnetism and Aeronomy (IAGA) in 2013. The present contribution defines the invalidating features of the PCS indices in question, conveys examples, and discusses the applications in peer-reviewed publications.

From a research data repositories’ perspective, offering data management services in-line with the FAIR principles is becoming more and more of a selling point to compete on the market. In order to do so, the services offered must be evaluated and credited following transparent and credible procedures. Several FAIRness evaluation methods are openly available for being applied to archived (meta)data. However, there exists no standardized and globally accepted FAIRness testing procedure to date. Here, we apply an ensemble of 5 FAIRness evaluation approaches to selected datasets archived in the WDCC. The selection represents the majority of WDCC-archived datasets (by volume) and reflects the entire spectrum of data curation levels. Two tests are purely automatic, two are purely manual and one test applies a hybrid method (manual and automatic combined) for evaluation. The results of our evaluation show a mean FAIR score of 0.67 of 1. Manual approaches show higher scores than automated ones. The hybrid approach shows the highest score. Computed statistics show agreement between the tests at the data collection level. None of the five evaluation approaches is fully fit-for-purpose to evaluate (discipline-specific) FAIRness, but all have their merit. Manual testing captures domain- and repository-specific aspects of FAIR. Machine-actionability of archived (meta)data is judged by the evaluator. Automatic approaches evaluate the machine-actionable features of archived (meta)data. These have to be accessible by an automated agent and comply with globally established standards. An evaluation of contextual metadata (essential for reusability) is not possible. Correspondingly, the hybrid method combines the advantages and eliminates the deficiencies of manual and automatic evaluation. We recommend that future operational FAIRness evaluation be based on a mature hybrid approach. The automatic part of the evaluation would retrieve and evaluate as much machine-actionable discipline specific (meta)data content as possible and be then complemented by a manual evaluation focusing on the contextual aspects of FAIR. Design and adoption of the discipline-specific aspects will have to be conducted in concerted community efforts. We illustrate a possible structure of this process with an example from climate research.

Research on Atmospheric Rivers (ARs) has focused primarily on AR (thermo)dynamics and hydrological impacts over land. However, the evolution and potential role of nearshore air-sea fluxes during landfalling ARs are not well documented. Here, we examine synoptic evolutions of nearshore latent heat flux (LHF) during strong late-winter landfalling ARs (1979–2017) using 138 over-shelf buoys along the U. S. west coast. Composite evolutions show that ARs typically receive upward (absolute) LHF from the coastal ocean. LHF is small during landfall due to weak air-sea humidity gradients but is strongest (30–50 W/m^2 along the coast) 1–3 days before/after landfall. During El Niño winters, southern-coastal LHF strengthens, coincident with stronger ARs. A decomposition of LHF reveals that sea surface temperature (SST) anomalies modulated by the El Niño—Southern Oscillation dominate interannual LHF variations under ARs, suggesting a potential role for nearshore SST and LHF influencing the intensity of landfalling ARs.

One of Venus’ most enigmatic landforms is Baltis Vallis, the longest observed channel on the surface (~7000 km long). Topographic conformity analysis shows that Baltis Vallis was modified over most of its observed wavelengths. Since the source location of Baltis Vallis is not well constrained, we analyze in both flow directions. For the commonly used northern source, topography across all wavelengths appears to be created after Baltis Vallis. However, for the southern source, topographic components with wavelengths longer than ~1900 km might have previously existed. Fourier analysis reveals three characteristic wavelengths, ~110-235 km, ~640±25 km and ~3500±1200 km. The shortest corresponds to deformation belts that cross Venus’ low plains, while the medium currently lacks an explanation. The longest is plausibly associated with the wavelength of dynamic uplift of the crust by mantle plumes. Higher resolution observations provided by the VERITAS mission can help resolve the source location of Baltis Vallis.

The Southern African Magnetotelluric Experiment (SAMTEX) involved the collection of data at over 700 sites in Archean to Proterozoic southern Africa, spanning features including the Kalahari Craton, Bushveld Complex and voluminous kimberlites. Here, we present the first 3D inversions of the full SAMTEX dataset. In this paper, we focus on assessing the robustness of the 3D models by comparing two different inversion codes, jif3D and ModEM, and two different subsets of the data, one containing all acceptable data and the other containing a smaller selection of undistorted, high-quality data. Results show that the main conductive and resistive features are imaged by all inversions, including deep resistive features in the central Kaapvaal Craton and southern Congo Craton and a lithospheric-scale conductor beneath the Bushveld Complex. Despite this, differences exist between the jif3D and ModEM inverse models that derive mainly from the differences in regularization between the models, with jif3D producing models that are very smooth laterally and with depth, while ModEM produces models with more discrete conductive and resistive features. Analysis of the differences between these two inversions can provide a good indication of the model resolution. More minor differences are apparent between models run with different subsets of data, with the models containing all acceptable data featuring higher wavelength conductivity variations than those run with fewer stations but also demonstrating poorer data fit.

South Asia is among the most populous regions of the earth which houses fast-developing economies. The unique geographical settings and socio-economic-demographic structure of the region make it highly vulnerable to the risks posed by climate change as documented by several comprehensive scientific research reports. Human-induced climate change signatures have already been noted in the form of increasing extremes (e.g. cyclones, droughts, floods, heat waves, thunderstorms, etc.), rising sea level, and changing monsoon patterns over the region. Though considerable progress has been made towards understanding the science of climate change, regional climate change consequences are still not well understood and limited by sparse observational networks and inadequate knowledge of region-specific physical processes which often lead to large spread and uncertainties in model projections. Based on the available literature, the chapter highlights the past, present, and future projections of climate over South Asia. Recent advances in observations and dedicated regional and earth system modeling activities over the region are also discussed alongside other emerging methodologies and tools which can lead to overall improvement in understanding of physical processes. We discuss the studies that have been carried out in the past and also the prospective gap areas that can be pursued in future through the use of a combined framework of modern observations-modeling-analysis techniques.