The use of geophysical tools for subsurface characterization is a common practice in environmental studies and georesources engineering. The electrical conductivity of the subsurface is strongly influenced by the different properties of the subsurface such as pore fluid chemistry, and consequently, by subsurface processes that affect the spatial distribution of that chemistry, such as the mixing dynamics of pore fluids. In the context of freshwater-saline water interaction in coastal areas, changes in solute spatial distribution are coupled to density-driven flow, which can thus be monitored via geoelectrical measurements. Here, we study the Rayleigh Taylor instability and subsequent convection occurring due to the density difference between two miscible liquids when the lighter one is positioned on top of the denser one, a configuration that is relevant for saltwater-freshwater interactions in coastal aquifers. We simulate the convective process and monitor it numerically by computing the transverse apparent conductivity of the medium in time, as the convection develops. We then look for correlations between the geoelectrical signal and a global scalar measure of the convective process' advancement, namely the variance of the solute concentration field.

After three foreshocks the day before (M5.0, M4.7 and M4.1, respectively), a strong M6.4 Petrinja earthquake occurred on December 29, 2020, followed by thousands of aftershocks (the strongest was a January 6 M5.0 earthquake). This paper presents a unique multihazard sequence of complex events resulting in numerous cover-collapse sinkhole failures. Although the area heavily impacted by the earthquake was larger than 1,000 km2, all 91 sinkholes appeared within a 4 km2 area surrounding Mečenčani and Borojevići villages located 20–25 km SE of the epicentral area, during the three months following the main earthquake. That area was also previously prone to seldom sinkhole appearances, as evidenced by 45 documented fossil sinkholes. All 91 sinkholes opened as post-seismic events; the first one (the second biggest, 10.8x9.8 m in diameter and 3.6 m deep) started to open six hours after the strongest earthquake. The biggest sinkhole, 25x23 m in diameter and 11.7 m deep, opened seven days after the main earthquake and one day before the strongest aftershock; its total volume is larger than volume of all other 90 new sinkholes combined. The Mečenčani and Borojevići villages surroundings is the only area where a 4–15 m thick sequence of Holocene soil built of unsaturated low plasticity clays with gravel and sand interlayers and lenses covers the heavily karstified carbonate bedrock composed of alternating highly porous Miocene limestones and calcarenites. The unconfined aquifer within a soil is underlain by a well-permeable confined karst aquifer in which the water pressure during wet periods becomes subartesian to artesian, enabling significant erosion and formation of numerous caverns at the soil–limestone contact. Continuous removal of eroded sediment by groundwater flow through karstified systems in carbonates gradually expands cavernous space until a final cover-collapse. The 2020–2021 Petrinja earthquake sequence significantly accelerated these processes, resulting in 91 cover-collapse sinkholes opened during a three-months period, instead of usually one sinkhole opened every few years as reported by local people. It is interesting to note that during the strongest earthquake the water level in the unconfined aquifer was very close to the surface, and in the underlying karst aquifer artesian conditions prevailed.

The most reliable way to develop poverty maps is through household surveys. However, in many developing countries, economic data from household surveys are infrequent. As a result, a data gap has emerged, making it impossible to identify and understand the locations of poor people. New approaches that integrate household survey data with non-traditional data sources (such as satellite imagery, call records, Wikipedia, google street view) using machine learning allows for improved resolution and scale in poverty mapping. Nevertheless, these studies developed poverty maps for study areas located in the same geographical region and did not map the location of poor people at the finest level (building level). Integrating income level from household survey data and building footprints from OpenStreetMap data with high-resolution satellite imagery, we extract the building rooftop images and classify them into two classes as poor(< = $5.50/day) and non-poor(> $5.50/day) based on the international poverty lines given by the world bank. We use these rooftop images as training data, develop a deep learning classification model, and estimate whether a building is poor or non-poor. We use physical factors like building area, elevation with rooftop images for transfer learning to contribute to the model’s accuracy. We attempt to build a versatile model that maps the locations of poor and non-poor people at the building level by developing, calibrating, and validating the model for Myanmar, Thailand, and Nicaragua study areas. Our findings show that for the model to travel well intra-regionally and inter-regionally, the study areas should be from the same geographical regions with similar roof types and percentages of people living in poverty. Combining the rooftop with income level is a fitting parameter to measure poverty, and roof color plays a crucial role along with the roof texture, shape to increase the model’s accuracy. The proposed methodology helps develop poverty maps for different income levels ($1.90, $3.20, $21.70, or any desired income level) from limited household survey data. This research study identifies the location and the total number of poor households living in a specific region which helps plan for effective poverty reduction, urban planning, and disaster prevention tailored to local conditions.

The Ethiopian sector of the East African Rift system (the Main Ethiopian Rift, MER) and Afar rift showcase advanced stages of continental breakup. Here the interplay between active continental rifting and rift-induced volcanism poses key questions regarding the mantle geodynamics of late-stage rift development. A particular subject of interest is the presence of hot mantle upwellings in the sub-rift mantle, which are inferred from geophysical imaging. Magma generation in the sub-rift asthenosphere depends on the temperature, lithology, and composition of the upwelling mantle material. Geophysical observations of the sub-rift mantle must therefore be supported by petrological studies aimed at understanding the physico-chemical conditions of melt production. In this study we investigate melt generation beneath the MER and Afar using a mantle melting model constrained by olivine crystallization temperatures and rare-earth element (REE) concentrations, both observed in rift zone lavas. Olivine crystallization, a proxy for magma liquidus temperature, is directly related to the thermodynamic and geochemical conditions of the melting mantle. Through application of an olivine-spinel aluminium exchange thermometer, we provide the first petrological olivine crystallization temperatures for MER and Afar basalts (1177±16°C and 1263±43°C respectively). A multi-lithology mantle melting model subsequently allows for inversion of our olivine crystallization temperatures and observed REE concentrations of rift magmas to estimate the temperature, lithology, and composition of the Ethiopian mantle. Our results suggest that the crystallization temperatures and REE distributions measured at the MER and Afar necessitate elevated mantle temperatures (Tp ≥ 1450 °C) relative to ambient mid-ocean ridge mantle. A thick mantle lithosphere (~60 km) is also required to provide deep garnet-field mantle melting inferred from REE distributions. We additionally conclude that an enriched and fusible pyroxenitic mantle component is necessary to match crustal melt thicknesses and observed REE concentrations. The composition of this pyroxenitic lithology is further explored through our inversions, and the contributions of enriched pyroxenitic melts to rift volcanism in the MER and Afar are subsequently compared.

Open, interdisciplinary science inevitably relies heavily on standards. Standards are those often unseen agreements that we take for granted when systems and processes are working fine. Yet standards work is perpetual, laborious, and sometimes contentious, especially for standards to work across diverse disciplines. Standards development, maintenance, and implementation is a complex, ongoing socio-technical process. NASA has developed a progressively open science policy and strategy that calls for the establishment of a data standards process reaching across the five diverse divisions of the Science Mission Directorate. This is a delicate exercise. We, therefore, seek to apply a holistic yet pragmatic approach to developing and maintaining a standards process. We adopt an ecological philosophy that focuses on the interactions within the data ecosystem and how standards facilitate those interactions. We couple high-level analysis with on the ground experimentation. We began by 1) mapping information ecosystem components (e.g. data centers, missions, services, protocols, users), 2) establishing how the components interact (e.g. sharing (meta)data, funding, personnel exchange), and 3) modelling system dynamics (e.g. creation of products from multiple data centers, redundant processes, shared services). The goal is to apply understanding of the ecosystem to real world applications (e.g. planning a new mission, implementing new policy requirements, improving process efficiency, etc.). We have also conducted studies of historical standardization efforts, documenting lessons learned and cautionary tales. We then contrast this more abstract work with real examples. We reviewed and assessed multiple existing standards development processes both within and external to NASA. We now work to implement an initial test process which can be further optimized. We seek to define a consistent approach for assigning persistent identifiers for research objects, especially for the purposes of citation. The experience from this relatively ‘simple’ test case adds a pragmatic perspective on how researchers and engineers actually work. This presentation will review the details of this methodology and our initial findings.

Tropical cyclones (TCs) are one of the most fascinating examples of organized convection. In idealized simulations of rotating radiative-convective equilibrium (RRCE), TCs can self-emerge without the need for a pre-existing disturbance. In a recent study, Ramírez Reyes and Yang (2021) showed that in contrast to prevailing knowledge (e.g., Muller and Romps (2018)), spontaneous TC genesis can occur without radiative and surface-flux feedbacks. Here we explore the hypothesis that under these conditions, the moisture-entrainment-convection (MEC) feedback is responsible for the spontaneous TC genesis. In the MEC feedback, a moister environment favors new deep convective events, and their associated large-scale circulations and detrainment processes further moisten the environment, leading to aggregation of deep convection. We examine the role of the MEC feedback in spontaneous TC genesis using RRCE simulations (Ramírez Reyes and Yang, 2021), in which we weaken the MEC feedback by relaxing the clear-sky specific humidity to its horizontal average throughout the entire column. TCs can still self-emerge when we weaken the MEC feedback, but TC intensity monotonically decreases as we reduce the relaxation time scale. TCs can no longer appear in the 100-day simulations when the relaxation time scale is reduced to 3 hours. We then relax the clear-sky specific humidity to its horizontal mean at individual vertical layers and find that weakening the MEC feedback below 7km significantly decreases TC intensity. However, nudging specific humidity above 7km has a much weaker impact. We will also present further analyses to test the hypothesis by using vorticity, the available potential energy (APE) budget and a vertically resolved moist static energy framework (Yao, Yang, Tan 2021). Ramírez Reyes, A., & Yang, D. (2020). Spontaneous Cyclogenesis without Radiative and Surface-Flux Feedbacks. arXiv preprint arXiv:2004.08662. Muller, C. J., & Romps, D. M. (2018). Acceleration of tropical cyclogenesis by self-aggregation feedbacks. Proceedings of the National Academy of Sciences, 115(12), 2930-2935. Yao, L., Yang, D., & Tan, Z. M. (2020). A Vertically Resolved MSE Framework Highlights the Role of the Boundary Layer in Convective Self-Aggregation. arXiv preprint arXiv:2008.10158

Post-wildfire mudflows have intensified in recent years due to extreme wildfire occurrence, causing significant damage and infrastructure threats. However, despite recent advancements, across-scale geotechnical characterization of mudflow onset and flow behavior remains a challenge. We present a novel experimental and theoretical understanding of the sand type and rain intensity roles on mudflow onset and composition, integrating micromechanics and laboratory experiments. The analysis shows that hydrophobic fine sand, a consequence of wildfires, significantly enhances raindrops’ downhill velocity and splash due to Cassie-Baxter-type surface, as opposed to medium or coarse sand, which affects raindrops as Wenzel surface wettability model. We use micromechanical and single-drop interactions with sand particles to explain erosion on the intermediate scale laboratory tests. Raining experiments on hydrophobic sloped flumes evaluate different slope failure mechanisms in fine, medium, and coarse hydrophobic sand as erosion patterns and seepage induced infinite slope failure in the case of embedded hydrophobic layers. The sand type also affects the spatio-temporal dynamic of erosion onset and distribution of eroded material and overflown rainwater. Surprisingly, we detected a possible equilibrium state where the eroded surface roughness changes affect water overflow and lead to an equilibrium state with very little subsequent erosion under constant rain intensity. On the other hand, erosion gradually increases after the rain starts, reaches a peak, and then subsides very quickly in coarse sand. In contrast, fine sand erosion continues for a longer time but decreases as the surface roughness increases. Furthermore, micromechanical investigation of mixtures of hydrophobic sands, water, and air gives an insight into air entrapment during flow and transport of mudflows. Hydrophobic sand particles attach to air bubbles and form agglomerates, contributing to the mixture heterogeneity and affecting flow and transport properties. Sand particle size, due to gravity, also plays a role in the amount and size of resulting agglomerates. Covering air bubbles with attached sand particles decreases the post-wildfire mudflow density up to 33% in laboratory conditions.

Equatorial Guinea’s Bioko Island is located in the Atlantic Ocean off the west coast of Cameroon. It is a volcanic island and the first off-shore expression of the Cameroon Volcanic Line. It is home to three shield volcanoes: Pico de Basile, Pico Biao, and Gran Caldera de Luba. Eruptive history is only known for Pico de Basile which erupted within the past 100 years, and steam vents were observed as recently as 2012. There is no permanent seismic monitoring; the closest seismic stations are in Cameroon and have not reported data since 2015. In Nov. 2017 Drexel University researchers, supported by the Bioko Biodiversity Protection Program (BBPP) and the Universidad Nacional de Guinea Ecuatorial (UNGE), installed 4 broadband seismometers. Two more stations were installed in March of 2019. Due to the COVID-19 pandemic data from the two most recent stations has yet to be retrieved and analyzed. Local collaborators reported a station was vandalized. It is unknown at this time how much data was recorded by this station. Preliminary earthquake detection and location was completed using an automated STA/LTA algorithm. S wave arrivals were added manually. Initial locations use the global IASP91 model and events were relocated using a local model. Events cluster into two areas: those near Bioko Island and those near Cameroon. Between 12-Dec-2017 and 17-Feb-2018, 77 events were recorded. Local magnitudes range between 0.16 and 2.61. Of these events, 49 are located near Cameroon and 28 are near Bioko. Most of the depths are upper to mid-crust. Analysis of the entire data set yields 458 events with 367 near Bioko Island and 91 near Cameroon. The range in local magnitude is -0.28 – 3.86. Our preliminary results show seismicity associated with Bioko Island as well as Cameroon. Locations match well with events recorded by a regional network in Cameroon. Stations were serviced in Feb. and Nov. 2018 and March 2019. Failures have been due to water infiltration, vandalism, and heavy cloud cover. Enclosures were redesigned after the Feb. 2018 service. All stations were upgraded to the new design in Nov. 2018 and solar panels were upgraded (20 to 35 watt) in March 2019. The next anticipated service was to be completed in March 2020 but was canceled due to the COVID-19 pandemic. The next anticipated service will occur in March 2022 if travel restrictions allow.

Upon the backdrop of steadily rising global average temperatures, it is the extreme weather events that are arguably more important and impactful than changing averages – especially on human health. This research examines trends in North America of three different parameters of extreme temperature events important to human thermal comfort and public health: their frequency, duration, and spatial extent. Most of the changes are expected; that is, with warmer temperatures there are more frequent extreme heat events that are lasting longer and covering more area. However, we highlight some intriguing divergences from this pattern. For example, despite quickly rising autumn temperatures in northern Canada, a concurrent decrease in temperature variability is resulting in extreme heat events remaining stable and is instead manifest more as significant decreases in extreme cold events. In parts of the western US, even though there is no significant trend in autumn mean temperatures, there is a significant rise in extreme cold events. And, in the southern High Plains in summer, despite little trend in averages, a more negative skew to the distribution is nonetheless leading to significant increases in heat events. Seasonal and geographic variability in the trends of extreme dew point events is also explored. For example, increases in extreme humidity events are ubiquitous throughout most of Canada, particularly in summer; but the US has a northeast (increasing humid events) to southwest (increasing dry events) dichotomy that is strongest in winter. While such nuances might complicate our efforts to broadly generalize the message of climate change, these distinctions suggest a renewed emphasis on local- to regional-scale analyses (rather than larger scales) when providing actionable climate information for planners and policymakers.

Multiple volcanic deposits, both pyroclastic and effusive, have been identified on the surface of Mercury. The modeling of volcanic processes on Mercury, particularly with respect to the amount and composition of volcanic volatiles, is hindered by a lack of existing experiments performed at or near Mercurian conditions. Most notable is Mercury’s extremely reducing nature (3–8 log units below the iron-wüstite buffer), which is well beyond the range of fO2s for which existing thermodynamic models are calibrated. The high carrying capacity of sulfur compared to carbon or hydrogen in reduced magmas, combined with remarkably high S concentrations in Mercurian surface materials, has led to the assumption that S is an important driver of volcanic activity on the planet. However, evidence for a primary graphite floatation crust as well as graphite present within Mercury’s regolith provide a mechanism for C-rich gas production via magma-graphite smelting reaction. Smelting, in which graphite is oxidized to CO and CO2 gas and melt oxide species are reduced to metal (e.g., Cgraphite + FeOmelt = COgas + Fe0metal), would also serve to remove O from the silicate melt, consistent with the production of a remarkably reduced surface environment. We carried out experiments to emulate conditions for graphite-induced smelting of three Mercurian magma compositions at high temperatures (ramped from ambient to 1195–1390 °C) and low pressures (8–10 mbar). The compositions of resultant gases were measured in situ via an evolved gas analyzer, and solid run products were analyzed by electron microprobe. Degassing vapor was always dominated by C-O-H species, and S degassing was not detected in any experiments. No significant C releases were measured in experiments using transition metal oxide-free starting silicate compositions, suggesting that transition metal reduction may be required to oxidize graphite to gas. Experiments that produced vapor formed Fe-Si metal alloy blebs, which were always in contact with residual graphite, strongly supporting metal and gas production via smelting between graphite and melt. Our results indicate that CO and CO2 are likely the most dominant volcanic degassers (and thus drivers of explosive volcanism) on Mercury, and that S degassing plays only a subordinate role, contrary to what has been hitherto assumed.

Digital core techniques based on CT scan imaging can accurately describe the pore space of rocks, which provides a significant tool for studying the influence of rock pore structure on its macroscopic physical properties. However, with the increasingly intensive use of CT scanning in the field of petrophysics, the various artifactual interferences accompanying the imaging itself have become more prominent. Common artifacts in core CT scanning imaging include ring artifacts, star artifacts, and hardening artifacts, etc. The presence of these artifacts greatly affects the imaging quality and as a result further affect the quality of subsequent image processing and segmentation. Therefore, the correction of scanning artifacts is very important. Generally, the artifacts are eliminated by improving scanning experiments or image processing. However, these traditional artifact correction methods, especially for hardening artifacts, have some common problems, such as unclean elimination or poor applicability. To solve the problems, we propose a new method for artifact correction. In this method, we calculate a local correction curve (surface) by sliding the 3D window vertically, and use this curve (surface) to eliminate hardening artifact interference in both vertical and horizontal directions. By applying the method to the digital cores, we find that it is not only effective in removing the effects of multiple artifacts but also in preserving the original slice information. The results show that the same density voxels corrected by bi-directional artifacts in the vertical and horizontal directions were more consistent in the gray-scale distribution, which means that the corrected slices avoided over-segmentation in the central region and extracted the complete pore structure in the edge region. As a result, the corrected high-quality core slices can be obtained. On this basis, we further compare the pore aspect ratio and specific surface area parameters extracted from the corrected and non-corrected slices. It shows that the artifacts correction has a significant effect on the extraction results of pore structure parameters, which reflects the importance of artifact correction in scanning imaging.

Tephra layers are often used to reconstruct past eruptions. However, accurate interpretation of tephra layers depends on their degree of preservation. We asked: how much volcanological information do terrestrial tephra layers typically retain? We addressed this question with a study of the tephra layer produced by the May 1980 eruption of Mount St Helens, comparing historical records of deposit thickness and grain size distribution with measurements made four decades after the eruption. Using published isopach maps as a guide, we looked for the tephra layer in locations 15 – 600 km from Mount St Helens, selecting sample locations we judged to have high preservation potential. We found that preservation of the 1980 tephra deposit was often extremely good: observed thickness, mass loading and grain size distributions were similar to equivalent measurements made in 1980. However, we also observed high variability in preservation on small spatial scales, and our results indicate that landscape-scale volcanological reconstruction is sensitive to sample number and location, even when many sites display excellent preservation. Tephra preservation is clearly a complex and contingent process influenced by climate, biology, topography, parent material (i.e., grain size, morphology and geochemistry) and time. The relative importance of these factors will vary from place to place. We propose that the only way to tease apart these factors – and to fully understand the information content of tephra layers - is through direct observation of tephra deposits (whether natural or experimental) over extended time periods.

The study of lunar plasma environment’s response to the magnetotail lobe condition is the main subject of our investigation in this report. Photoionization and charge exchange of protons with the lunar exosphere arethe ionization processes included in our model. The computational model includes the dynamics of heavy Na+ pickup and ambient magnetospheric ions. The electrons are considered as a fluid.The lunar interior is considered as a weakly conducting body. In this report we consider for the first time a formation of lunar plasma structures, wakes, and a generation of low-frequency electromagnetic waves by using a self-consistent hybrid kinetic modeling. The input parameters were taken from the ARTEMIS observations. At an early stage the Moon with exosphere and conducting core excites whistler waves in case of Sub-Alfvenic/sonic interaction. At a later stage an excitation of the Alfven wave is observed. The topology of the Alfven waves is approximately similar to the Alfven wing near the planetary moons (Io, Europa etc.). The physics of the Moon-magnetotail lobe interaction is also close to the physics of the interaction between plasma clouds (expanding and not expanding) and ambient magnetospheric plasma. The heavy pickup ions create a large structured halo with space scale of more than 10 R_{E} in the direction of the background field. The modeling also shows an excitation of the compressional waves due to expansion of heavy exospheric pickup ions. The lunar model with weaker interior conductivity excites lower levels of the wave activity. This work was supported by NASA Award (80NSSC20K0146) from Solar System Workings Program (NNH18ZDA001N-C.3-SSW2018). Computational resources were provided by the NASA High-End SupercomputingFacilities (Aitken-Ames, Project HEC SMD-20-02357875).

Analysis of the time-dependent behavior of the buoyant plume rising above Grotto Vent (Main Endeavour Field, Juan de Fuca Ridge) as imaged by the Cabled Observatory Vent Imaging Sonar (COVIS) between September 2010 and October of 2015 captures long-term time-dependent changes in the direction of background bottom currents independent of broader oceanographic processes, indicating a systematic evolution in vent output along the Endeavour Segment of the Juan de Fuca Ridge. The behavior of buoyant plumes is a convolved expression of hydrothermal flux from the seafloor and ocean bottom currents in the vicinity of the hydrothermal vent. Plume behavior can be quantified by describing the volume, velocity and orientation of the effluent relative to the seafloor. Using three-dimensional acoustic images by the COVIS system, we looked at the azimuth and inclination of the Grotto plume in 3 hour intervals and identified a bimodal shift in their bending from NW and SW to SE in 2010, 2011, and 2012 to single mode NW in 2013 and 2014. Modeling of the distribution of azimuths for each year with a bimodal Guassian indicates that the prominence of southward bottom currents decreased systematically between 2010 and 2014. Spectral analysis of the azimuthal data showed a strong semi-diurnal peak, a weak or missing diurnal peak, and some energy in the sub-inertial and weather bands. This suggests the dominant current generating processes are either not periodic (such as the entrainment fields generated by the hydrothermal plumes themselves) or are related to tidal processes. The surface wind patterns in buoy data at 2 sites in the Northeast Pacific and the incidence of sea-surface height changes related to mesoscale eddies show little systematic change over this time period. Given the limited bottom current data for the Main Endeavour Field and other parts of the Endeavour segment, we hypothesize that changes in venting either within the Main Endeavour Field or along the Endeavour Segment have resulted in the changes in background currents. Previous numerical simulations (Thomsen et al 2009) showed that background bottom currents were more likely to be controlled by the local (segment-scale) venting than by outside ocean circulation or atmospheric patterns.

Recent observation reveals a stunning fact that the coastal tides are experiencing a rapid change in the last century in several places in the world. To achieve a wide and refined understanding of the phenomenon, high-accuracy tide level data is needed more than ever. In-situ measurements – the traditional and main data source to support tidal harmonic analysis – are often sparse and limited to fixed positions, insufficient to provide information about the spatiotemporal variability of tidal processes beyond the tidal gauges. Satellite altimetry may fundamentally change the situation. This technology measures water level with increased spatial coverage and resolutions. However, satellite altimetry has not been used in tidal analysis due to two major limitations in the harmonic analysis: a) a minimum length of sampled observed data is required to recognize a sufficient number of tidal constituents according to the Rayleigh criterion and b) data sampling/acquisition frequency must be at least two times the major tidal frequencies to avoid the aliasing issue dictated by Nyquist theorem. To address these issues, a novel compressed-sensing approach is proposed to break the limitations. In this method, the prior information of the regional tides (e.g., a reference tidal station near the location of interest) is collected to support a stepwise optimization process to obtain the amplitudes and phase terms of the tide signal for data series with different lengths and time intervals. Instead of least-square-fit approach, stochastic gradient decent is employed using Pytorch. A preliminary study shows that the proposed method can generate the tidal amplitudes and phases with a sampling interval of 16 days and a total data length of 30 days with an acceptable error. The results of this study can be useful to determine an optimum frequency and length for tidal data acquisition for the upcoming SWOT (Surface Water Ocean Topography) satellite, which is supposed to be launched in November 2022 to measure sea and terrestrial water level around the globe for three years and with average revisit time of 11 days.

High producing grazed pastures occupy almost one third of Aotearoa New Zealand (268,000 km2) and produce exported protein to feed more than 40 million people. Trends within farming systems include increasing rates of urea fertiliser use and greater concentrations of N via urine deposition, which enhance N2O emissions and NO3 losses. Focussing on N-sensitive lake catchments, we ask: what tools can reduce uncertainties in the sources and magnitude of N losses, quantify the potential to reduce excess N, and clarify rates of change in N budgets. Dual-isotope NO3 measurements differentiate urine and urea-derived sources (δ15N < 4 ‰) from mineralized soil organic N (δ15N of 4–8 ‰). Nitrate in streams draining the Rotorua region’s pumice soils and aquifers is dominated by urine and urea sources, compared to streams flowing from finer soils that only show these lower δ15N values when large runoff events activate surface flow paths. We have confirmed that shifts in stream water δ2H and δ18O toward the values observed in the major rainfall event coincide with elevated [NO3] and low δ15N representative of urine and urea-derived sources. A combination of δ2H and δ18O and Δ14C in dissolved inorganic carbon (DIC) largely confirmed tritium-based assessments, suggesting lag times of many decades in some aquifers, but rapid responses to recent N inputs elsewhere. In the Southland region, where tile drainage enables effective pasture growth, we explored flow responses in a drainage tile where NO3 consistently showed an imprint of denitrification (δ15N > 12 ‰). In this location following major rainfall, [NO3] remained stable but dissolved organic N concentrations increased, at times associated with stormwater δ2H and δ18O shifts. The Δ14C in DIC yielded apparent ages of several hundred years during low-flow periods, suggesting ongoing breakdown of soil organic matter releases N, which should be considered in farm and catchment N budgets. We conclude that monitoring N concentrations and multiple isotope species can resolve control points of N excess, which reveal targets for potential mitigation. Specifically, N content in clover-ryegrass pastures seasonally exceeds N demand in grazing animals, suggesting alternate species or feeds could reduce animal urinary N excretion, and therefore limit soil-derived N2O emissions and NO3 losses.

Integrating detrital zircon U/Pb and whole-rock Nd data throughout the Himalayan arc provides the means to distinguish between the Tethyan (TH), Greater (GH), and Lesser Himalayan (LH) tectonostratigraphic zones within the thrust belt. In the Kaghan valley of northern Pakistan, debate exists over the existence and location of the Main Central thrust (MCT) and the tectonostratigraphic affinity of the rocks in the Hazara-Kashmir syntaxis. Three new detrital zircon U/Pb age spectra and two new εNd(0) values from the footwall rocks of the Batal fault yield 1.0-2.0 Ga age populations and an average εNd(0) value of -13.6. Four new detrital zircon U/Pb age spectra and two new εNd(0) values from the hanging wall rocks have primarily <1.2 Ga age populations and an average εNd(0) value of -16.7. Most detrital zircon analyses exhibit Pb-loss from younger (<600 Ma) intrusive or metamorphic events. The absence of zircon <1.0 Ga in the footwall samples indicates that they are LH rocks, while εNd(0) values indicate that they are not Paleoproterozoic LH rocks, but are comparable to other Meso- and Neoproterozoic LH rocks along the Himalayan arc. Neoproterozoic and younger detrital zircon age populations from the hanging wall samples and the presence of ~47 Ma intrusive leucogranite indicate that these are either TH or GH rocks, with εNd(0) values also consistent with TH or GH values. Combining these data show that the hanging wall rocks are either TH or GH rocks, and that the footwall rocks are Mesoproterozoic LH rocks. In most places, the MCT is defined as GH rocks thrust over LH rocks. However, in NW India, the GH/LH contact is buried in the subsurface, and the MCT at the surface is a TH/LH contact. Therefore, these data define the Batal fault in the Kaghan valley as equivalent to the MCT, with TH/GH rocks thrust over LH rocks, and link it with the Indus River valley to the west in Pakistan and NW India to the east.

Over the last several decades, heat waves have notably increased in frequency, intensity, and duration in the United States. Studies have credited these trends to a warming climate, and therefore, it is expected that extended periods of consistent and abnormally hot temperatures will continue to occur through the 21st century. Heat waves alone can have harmful impacts on the human body, but when coupled with high humidity, these events can become especially threatening. While other studies have assessed the human health effects of extreme humid heat waves, this study aims to determine the source region and pathway of air parcels during these events, while also understanding the land-surface processes that amplify and dampen the amount of atmospheric moisture present as an air parcel reaches a target region. Through the use of the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model, atmospheric moisture exchanges and concentrations are analyzed for the three days prior to a humid heat wave at Boston, MA, Burlington, VT, Albany, NY, and Philadelphia, PA, between June and August of 1980-2019. Four major source regions are identified as being largely responsible for the atmospheric moisture present during heat waves across these cities: the Atlantic Ocean, Gulf of Mexico, Great Lakes, and terrestrial evapotranspiration from the Midwest and Mid-Atlantic regions of the United States. Geographical location and proximity to water of each city has a notable influence on source region and number of humid heat waves occurring throughout the period of study. At Boston and Philadelphia, the two leading sources of moisture are the Atlantic Ocean and Gulf of Mexico, while at Burlington and Albany, the Great Lakes and terrestrial evapotranspiration are more dominant. Stark differences are also noted between the source regions and trajectories of humid versus dry heat waves at a given location. Examining the sources and paths of air parcels leading up to extreme heat events, as well as analyzing the atmospheric-land interactions that take place during that time, will provide a comprehensive understanding into the importance of a given moisture source region on a particular location, and how a warming climate may ultimately alter the degree to which a source region is responsible for atmospheric moisture in the future.