bluuebunny/crossref_metadata_2025 huggingface dataset:
Sea-level rise projections of Petermann Glacier, Greenland, modeled using synchronously coupled subglacial hydrology and ice flow dynamics
Authors: Ehrenfeucht Shivani , Morlighem Mathieu , Rignot Eric , Dow Christine
Published: February 2023

Greenland ice shelves are known to display seasonal speedups of ice velocity which can be attributed to ice front position or to meltwater runoff, depending on which glacier is being examined. However, it remains uncertain if the seasonality of glacier speed will be impacted by climate change in the coming century. Current projections of glacier dynamics under 21st century climate forcings do not include subglacial hydrology, so it also remains unknown if it will play any important role in evolving glacier dynamics under different climate change scenarios, or ultimately have an impact on sea-level rise projections. Here we present a model with synchronous coupling of ice dynamics and subglacial hydrology applied to Petermann Glacier in northern Greenland. Petermann exhibits a summer-time acceleration of roughly 15% as compared to its baseline winter velocity, which is likely the result of subglacial hydrology. Although it has been relatively stable in recent years, as one of the largest marine terminating glaciers in northern Greenland, whether or not Petermann remains stable will have a significant impact on the sea-level contribution of the northern sector of the ice-sheet. We use climate through 2100 to investigate how the subglacial hydrologic system may evolve in a warmer climate and to test if including hydrology changes the stability of Petermann under future climate scenarios using the Ice-sheet and Sea-level System Model (ISSM) which includes the Glacier Drainage System (GlaDS) model. We compare glacier evolution and projected sea-level rise for three model configurations: one with synchronously coupled subglacial hydrology and ice dynamics, a second with asynchronous coupling where subglacial hydrology is calculated with static ice geometry and velocity but ice dynamics are calculated using effective pressure from GlaDS output, and a third where subglacial hydrology is excluded entirely from the model setup.  Results show a significant increase in projected sea-level rise by the end of the century and differing patterns of grounding line migration and ice thinning when subglacial hydrology is included in the model configuration for Petermann.
The potential of tree-ring chronologies to global-change studies in the tropics: a quantitative review
Authors: Groenendijk Peter , Babst Flurin , Granato Souza Daniela , Locosselli Giuliano , Mokria Mulugeta , Pumijumnong Natshuda , Trouet Valerie , Panthi Shankar , Zexin Fan , Zuidema Pieter ,   Tropical Tree-ring Network
Published: February 2023

Tropical forests and woodlands are key components of global carbon and water cycles and due to their importance we need to better understand present and future tropical tree growth responses to climatic variation. Tree-ring analyses provide long-term datasets from which such responses can be derived. A substantial number of tropical tree-ring chronologies exist with hundreds of topical tree species showing potential for tree-ring analyses. Despite this large potential, a quantitative analysis of the distribution and characteristics of tropical tree-ring chronologies is missing. We compiled a network of >490 tropical ring-width chronologies to assess their geographic and climatic distribution, and the gaps therein. To evaluate the potential for climate reconstructions we assessed the timespan covered by these chronologies, the strength of their common growth signal (rbar), where the strongest climate-growth correlations are found, and how these chronology attributes correlate with mean climatic conditions per site. Finally, we used species-distribution modelling to identify regions with high potential for building long chronologies. We answer these questions at pantropical level and address important differences between continents and between angiosperms and gymnosperms. Tropical chronologies have been built in all continents and tropical climate types but chronology building is biased towards high-elevation locations and gymnosperms, with clear gaps in warmer and wetter climates, on the African continent and for angiosperm species. Chronology length correlated negatively with mean annual temperature (MAT), while the common growth signal decreases with increasing mean annual precipitation (MAP) and MAT. Drier sites have the most responsive chronologies: the strength of the precipitation-growth correlations decreases with increasing MAP, but showed no correlation with MAT. Tropical dendrochronological studies already cover a substantial part of the tropics and most areas are expected to have 5 to 15 species with potential to generate centennial chronologies. This study wil provide an important basis to select species and areas to expand dendrochronological studies to underrepresented areas and improve our understanding of the climatic drivers of tropical forest tree growth. 
Underestimation of reported methane emissions, and air pollutant loadings, from upstream oil and gas activities in Canada
Authors: Lavoie Martin , Risk David , MacKay Katlyn , Bourlon Evelise
Published: February 2023

Canada was an early adopter of methane regulation in the oil and gas sector, and recently announced a more ambitious goal to reduce 75% of methane emissions by 2030. New stricter methane regulations should also help reduce loading of air pollutants typically associated with methane emissions (H2S, VOCs, ozone). To examine regional emission trends and to derive an inventory estimate for Canada’s upstream oil and gas sector, we measured methane emissions at 6650 sites across six major oil and gas producing regions in Canada. Our research suggests that methane emissions from the oil and gas industry are underestimated in Canada by ~1.5. For Canada’s largest producing province, Alberta, we found a greater than 1000-fold variation in methane intensity per unit of fossil energy production within the cohort of oil and gas producers. Producer self-published methane emission intensities in ESG materials showed a low bias and tended to mirror regulatory submissions that require reporting only on specific source types. Our measurements suggest that methane-associated pollutants produced by oil and gas activities are also underestimated and communities near these activities may face higher loading of methane-accessory contaminants than might be predicted by Canada’s National Pollutant Release Inventory (NPRI). Using accepted pollutant emission factors, reported flaring and other combustion activity, the federal methane inventory, and our methane measurements, we generated air quality exposure maps reflecting air pollutant loads on Canadian communities. Stricter methane regulation has the potential to significantly decrease methane, but also pollutant loads in several heavy oil communities including the Lloydminster - Bonnyville area.
Assessment of phthalic acid esters (PAEs) in waters of the Atoyac River basin, Puebla-Tlaxcala, Mexico
Authors: Vázquez Tapia Ivón , Mora Abrahan , Dueñas-Moreno Jaime , Mahlknecht Jürgen
Published: February 2023

The present study demonstrated the presence of phthalates in the Atoyac River, considered the second most polluted river in Mexico. The results showed that 9 PAES were detected in river water of the 15 PAES studied. Among the detected PAES, Bis-(2-methoxyethyl) phthalate (DMEP), Bis(4-methyl-2-pentyl) phthalate (BMPP), Di-n-hexyl phthalate (DNHP) and Dipentyl phthalate (DPP) had concentrations higher than those reported in highly polluted worldwide rivers.The main source of phthalate pollution in the river was the discharges of untreated or poorly treated wastewater coming from the metropolitan area of Puebla and Tlaxcala states, which holds hundreds of industries. The distribution study of the sampling sites indicated that the highest concentrations of phthalates were detected in industrial areas.  Sources of phthalates can be related to the presence of chemical plants, textile production, uses of solvents in the production of paper and mainly in the manufacture of plastic products.In addition, the concentrations of the five most detected phthalates throughout the Atoyac River basin showed a decrease in the lotic water body (Valsequillo reservoir), which acts as a sewage oxidation lagoon, degrading some organic pollutants (including phthalates) present in the river waters
The study of the changes in precipitation induced by intensified urbanization and climate change by observational records
Authors: Huang Jinhui Jeanne
Published: February 2023

Both climate change and intensified urban development will affect the temporal and spatial distribution of rainfall. There is still a lack of relatively quantitative and comparative studies. Most cities in China entered the rapid urbanization stage around 2000. This study focuses on the megacities Beijing, Shenzhen and Hong Kong. Based on rainfall observation data and land use and other remote sensing image data, this study investigates the impacts of the impervious areas on the temporal and spatial changes of short-duration and long-duration heavy rainfall before and after rapid urbanization. The impact of climate change on rainfall intensity is also analyzed. The results show that there are huge spatial shifts in rainfall after rapid urbanization. For example, it is observed that the center of the heavy rainfall shifts from northeast to southwest, and the hydrological homogenous areas in Beijing have increased from two to three after rapid urbanization. Meanwhile, with the influence of climate change, the intensity of rainfall is increasing, but due to urbanization, the increase varies greatly in each hydrological homogenous area. Shenzhen and Hongkong, the neighbor cities without physical boundaries, have entered into different urbanization stages since 1990. Hong Kong has developed very slowly, while Shenzhen has developed very rapidly. As a result, the short-duration heavy rainfall is mainly concentrated in Shenzhen, and the long-duration heavy rainfall is mainly concentrated in Hongkong. The short-duration heavy rainfall in Shenzhen mostly occurs at noon, while that in Hong Kong mostly occurs in the morning. The urbanizations of Hong Kong and Shenzhen are different, which resulted in different impacts on rainfall in these two cities. This study examines the impact mechanisms of urbanization and climate change on rainfall in cities in different climate zones. It provides scientific basis in supporting the city planning and the development of resilient cities.
Middle Jurassic at Praia da Mareta, Algarve
Authors: Assunção Maria
Published: February 2023

Portugal is known for its extraordinary beaches and inviting climate. But on our beaches there is much more to discover than just sun and sea. There is a country rich in geological data that allows us to reconstruct our history.By observing geological occurrences in a given location, it is possible to understand what kind of environments existed and how they evolved. Aspects such as present lithologies or fossils allow deducing environments that existed in the past and, through tectonic and geomorphological aspects, it is possible to deduce how the site evolved after the deposition of strata.Praia da Mareta, located in the Algarve Basin, is a place of high scientific and didactic value of the Portuguese South Zone’s Geological Heritage, particularly important for reconstructing the history of the Earth in the Jurassic period. This contemporary basin of the Lusitanian Basin (West Rim) would have been formed during the opening of the Tethys and Atlantic Ocean, undergoing an inversion, a phenomenon induced by the collision of the African and Eurasian plates in the Upper Cretaceous. At Praia da Mareta, the rocks that emerge are practically from the Middle Jurassic to the Upper Jurassic.Due to this, Praia da Mareta is an excellent example of how the Algarve region, so known for its beaches, has an admirable geological wealth and still little explored by tourists.One of the goals of this work is to develop interest in geology and geological research, to develop science for citizens, involving them in geoscientific research. Simplifying geological information and developing interest in geoscientific research brings citizens closer to nature, promoting sustainability and heritage protection, namely geological heritage.
Energetic Particles in the Outer Heliosphere
Authors: Mostafavi Parisa , Hill Matthew , Kollmann Peter , Brandt Pontus , McNutt Ralph , Stern Alan , Shrestha Bishwas , Bagenal Fran , Singer Kelsi , Verbiscer Anne , Spencer John
Published: February 2023

Nonthermal energetic pickup ions (PUIs), created in the heliosphere by charge exchange between solar wind ions and interstellar neutral atoms, play an essential role in understanding solar wind evolution in the outer heliosphere and the structure and dynamics of the global heliosphere. New Horizons spacecraft, launched in 2006, is now located at about 55 au from the Sun, exploring the outer heliosphere, and is the only spacecraft equipped with proper instruments to measure nonthermal energetic pickup ions (PUIs) in the outer heliosphere for the first time. Its observations showed that energetic PUIs dominate the internal pressure of the outer heliosphere, with PUI pressures larger than the thermal solar wind and magnetic pressures outside ~ 20 au. At these distances, PUIs contribute substantially to heating and slowing down the solar wind. Moreover, New Horizons observations showed that PUIs mediate shock waves in the outer heliosphere. Here, we give an overview of the energetic particles in the outer heliosphere and their effect on shocks. We present the in situ observations of the hydrogen and Helium PUIs made by New Horizons' SWAP and PEPSSI instruments. Finally, we present some of the most important open questions related to the outer heliosphere that future studies and space missions should address.
Recycling mercury at a convergent margin from Nankai Trough to southwest Japan
Authors: Takeuchi Akinori , Masuda Harue
Published: February 2023

In the southwest Japan, located at the eastern edge of Eurasian plate, dehydrated water from subducting Philippine Sea Plate from the Nankai Trough issues without magmatic activity as thermal brines. Those brines contain high amounts of mantle derived components, and mercury may be one of those components. Mercury contamination is found in shallow groundwaters (>0.1 µg/kg) and soils (>200 µg/kg) along peripheral active faults of Osaka Basin, where subducting slab from the Nankai Trough appears deeper than the surroundings. Occurrence of the mercury contaminated groundwater also corresponds to the areas of deep low frequency tremor, which is known as a phenomenon occurring in relation to dehydration from subducting slab.In order to specify the source(s) of mercury above described, mercury concentration and stable isotopes were analyzed for the sediments down to 2200 mbsf (meters below seafloor) taken from drilled cores at Kumano-nada basin IODP Site 0002, where accreted oceanic and forearc sediments are deposited. The mercury concentration, ranging 30-240 µg/kg, except three of 330-820 µg/kg of samples taken from ≥2000 mbsf. The range of 30-240 µg/kg is the same as those of surface sediments of ocean bottom of the study area. The high concentrations seemed due to high contribution of volcanogenic materials. The mercury stable isotopes values, –0.26 to –0.83 ‰ for δ202Hg and no shift of Δ199Hg and Δ201Hg, indicating geogenic origin without biogenic and/or photochemical alteration. The isotope values are in the similar range of those in the shallow groundwater in the Osaka Basin. The isotope values of δ202Hg are slightly smaller than that of mantle (0 ‰). These observations would be direct evidence that the mercury deposited in the subducting slab comes up with upwelling fluids.Ocean scientific drillings have dissolved material cycles and the associating geological phenomenon, especially related to volcanic and seismic activities, at convergent margins related to subduction factory. From the point of views of concentration of useful elements, subduction factory is an important role for formation of ore deposits mainly via magmatic and the associating hydrothermal activities, which also cause the contamination of toxic elements. However, this study gives possible contamination of hydrosphere and pedosphere with toxic elements via non-volcanic tectonic activity.
Mineral Association Analysis: Predicting unknown mineral occurrences and improving our understanding of mineralogy
Authors: Prabhu Anirudh , Morrison Shaunna M. , Eleish Ahmed , Fox Peter , Golden Joshua J. , Downs Robert T. , Perry Samuel , Burns Peter C. , Ralph Jolyon , Hazen Robert M.
Published: February 2023

Minerals are the oldest surviving materials from the formation of our solar system. They are time capsules that store and provide information about the evolution of Earth and other planetary bodies. In addition to being a cornerstone of geoscience research, minerals also have economic, industrial and commercial importance in many sectors of society. One of the fundamental questions in mineralogy and geosciences in general is “Where to find minerals?”. Due to the complex and intertwined nature of natural systems, it has been hard to predict the occurrences of minerals. However, with increase in the volume and accuracy of mineral data and rise of mineral informatics, data science and analytics methods can be developed to answer this fundamental question in mineralogy.  In this contribution, we present “mineral association analysis”, a method to: 1) Predict the mineral inventory for any existing locality. 2) Predict previous unknown localities for any given mineral. Mineral association analysis is a machine learning method that uses association rule learning to find interesting patterns based on mineral occurrence data. Using mineral association analysis, we have been able to predict locations of critical minerals, such as minerals with Li- and Th-bearing phases, predict the mineral inventory of mars analogue sites, and even understand how mineralization and mineral associations changed through deep time.
G3P: A global data set of groundwater storage variations based on satellite gravimetry
Authors: Sharifi Ehsan , Güntner Andreas , Haas Julian , Dorigo Wouter , Jäggi Adrian , Ruz Vargas Claudia ,   G3P team
Published: February 2023

The Global Gravity-based Groundwater Product (G3P) developed a satellite-based groundwater storage anomaly (GWSA) data set as a prototype for a future product within the EU Copernicus Climate Change Service. As the world’s largest distributed freshwater storage, GW is a key resource for mankind, industrial, and agricultural demands. In Copernicus, there is no service available yet to deliver data on this fundamental resource, nor is there any other data source worldwide that operationally provides information on changing groundwater resources in a consistent way, observation-based, and with global coverage. Therefore, G3P developed the global data set of groundwater storage variations as a cross-cutting extension of the existing Copernicus portfolio. G3P capitalizes from the unique capability of GRACE and GRACE-FO satellite gravimetry as the only remote sensing technology to monitor subsurface mass variations, and from other satellite-based water storage products to provide a data set of groundwater storage change for large areas with global coverage. G3P is obtained by using a mass balance approach, i.e., by subtracting satellite-based water storage compartments (WSCs) such as snow water equivalent, root-zone soil moisture, glacier mass, and surface water storage from GRACE/GRACE-FO monthly terrestrial water storage anomalies (TWSA). For a consistent subtraction of all individual WSCs from GRACE-TWSA, the individual WSCs are filtered in a similar way as GRACE-TWSA, where optimal filter types were derived by analyses of spatial correlation patterns. G3P groundwater variations are provided for almost two decades (from 2002 to 2020), with a monthly resolution, and at a 0.5-degree spatial resolution globally.In this contribution, we also illustrate selected results of the G3P-based GWSA data set, including the global trends of groundwater storage and the uncertainties of the GWSA data as well as of the contributing storage compartments. The GWSA is also evaluated against in-situ groundwater observations, using 13 large aquifers worldwide with available in-situ groundwater observations. Results show a high correlation between the variations of in-situ groundwater data and G3P-based GWSA for most of the aquifers, such as the Ogallala aquifer, Floridan aquifer, Paris Basin, South of Outer Himalayas aquifer.This study has received funding from the European Union’s Horizon 2020 research and innovation programme for G3P (Global Gravity-based Groundwater Product) under grant agreement nº 870353.
The Observations of Deimos from the Emirates Mars Infrared Spectrometer (EMIRS)
Authors: Smith Nathan , Edwards Christopher , Osterloo Mikki , Christensen Philip , Anwar Saadat , Pilinski Emily , Wren Paul , Noss Dale , Rios Ken , Dickenshied Scott , Al Matroushi Hessa , Deighan Justin , Parker Jeffrey , Sharaf Omran
Published: February 2023

We present the initial views of the surface of Mars’ outer moon Deimos as observed by the Emirates Mars InfraRed Spectrometer (EMIRS), a Fourier transform infrared spectrometer observing from 6-50 µm with a spectral sampling of up to 5 cm-1. The primary science goal of the Emirates Mars Mission (EMM) is to study the variability in Mars’ atmosphere. As part of a coordinated campaign, the EMM spacecraft has adjusted its orbit into a resonance with Deimos, where it will periodically fly by the moon. Beginning the spring of 2023, EMIRS will collect numerous thermal infrared spectra of Deimos’ surface with a spatial resolution ranging from ~1-10 km. These observations will be the best-resolved infrared views of Deimos to date. Our planned observations achieve nearly complete global coverage of the surface, and span a range of local solar times, enabling investigations of both compositional and thermophysical properties. We will discuss these observations and initial findings. 
The search for path-dependency mechanisms using physically-based soil-landscape modelling of landslides
Authors: Temme Arnaud , Sadeghnejad Mostafa , Singh Sodhi Harsimran , Samia Jalal
Published: February 2023

The spatial pattern of landslide susceptibility is a key input for decision making by many natural hazard agencies. Therefore, the estimation of landslide susceptibility maps has received much attention in the last decades. Increasingly, such maps are produced by statistical methods that relate the locations of observed landslides to geofactors such as slope steepness or vegetation density. Almost without exception, these susceptibility assessments are entirely spatial. At the same time, recent studies of large multitemporal landslide datasets have shown empirically that landslide susceptibility changes over time as well as space, as a result of the impact of recent nearby landslides. In at least two study sites, places near previous landslides are temporarily more susceptible to landsliding, sometimes substantially so. Several candidate mechanisms underlie this form of complexity (called path-dependency) in the landslide system, and targeted field measurements in landslide-prone study sites should be recorded to fully understand which mechanism is most important.Awaiting such measurements, physically-based mechanistic modelling of landslide impacts in the soil-landscape system can help explore the possible mechanisms. Here, we report on our development of landslide simulation capabilities in soil-landscape evolution model LORICA. In this model, landslides affect not only surface elevation, but also local soil and vegetation properties. Since other processes in the model also affect these properties, the impact of landslides is not permanent. Applied to a hypothetical soil-landscape, this model allows us to explore whether a) local topographic effects such as oversteepening, b) temporarily changed soil hydraulic parameters, or c) disruption of vegetation and roots, are the most likely mechanisms behind landslide path-dependency.
Observed trends in the snow-to-liquid precipitation ratio over Romania
Authors: Amihăesei Vlad-Alexandru , Micu Dana Magdalena , Dumitrescu Alexandru , Cheval Sorin , Bîrsan Marius-Victor , Sfîcă Lucian
Published: February 2023

In the regions with temperate climate, solid precipitation usually prevails during the winter time. However, a warming climate could alter the timing of snow accumulation and resulted amounts with major impact on the hydrological cycle. This study analyses the changes in the monthly snow-to-liquid precipitation ratio (SLPR)  over the October-May interval in Romania, based on daily precipitation, air temperature and snow depth data provided by 114 weather stations from the national meteorological monitoring network, over the 1961-2021 period. The observed trends showed a country-wide and significant decline in SLPR. The most notable decline is observed during the late winter and early spring months (February-March), with decreasing trends at over 70% of the weather stations, although only 20% suggest statistically significant changes (p value < 0.05). The autumn months (October and November) depict no statistically trends. The trends observed in the late spring (April and May), show a strong decline in SLPR for most mountain weather stations (above 1,000 m), at rates that could exceed 5% per decade (e.g., Tarcu weather station, 2,200 m, the Southern Carpathians). Evidence of elevation dependency of SLPR trends has been found in spring. The results show that the SLPR declines with altitude, especially in April (R2 = .30) and May (R2 = .67), when the correlations are statistically significant (p<0.05).This work was co-funded by the European Social Fund, through Operational Programme Human Capital 2014-2020, project number POCU/993/6/13/153322, project title  “Educational and training support for PhD students and young researchers in preparation for insertion into the labor market”.   
New ice core proxy for reconstructing past wind variability in the Atlantic sector of the Southern Hemisphere Westerly Wind belt
Authors: Tetzner Dieter , Thomas Elizabeth , Allen Claire
Published: February 2023

The Southern Hemisphere Westerly Winds play a critical role in the global climate system by modulating the upwelling and the transfer of heat and carbon between the atmosphere and the ocean. Since observations started, the core of the westerly wind belt has increased in strength and has contracted towards Antarctica. It has been proposed that these deviations are among the main drivers of the observed widespread warming in West Antarctica. However, the lack of long-term wind records in the Southern Hemisphere mid-latitudes hinders our ability to assess the wider context of the recently observed changes.Here, we present the diatom record preserved in an ice core retrieved from the Ellsworth Land region, West Antarctica. The diatom abundances and species assemblages from this ice core represent the regional variability in wind strength and atmospheric circulation patterns over the Atlantic sector of the Southern Ocean. We use this novel proxy to produce an annual reconstruction of winds in the Atlantic sector of the Southern Hemisphere Westerly Wind belt over the last 300 years. This wind reconstruction allows tracking changes in the strength and position of the westerly winds during the late Little Ice age and exploring the link between the recent increase in wind strength, greenhouse gases and ozone depletion in the atmosphere.
Influence of future 2-degree-global-warming regional sea-ice loss on the Arctic stratospheric polar vortex
Authors: Xu Mian , Screen James , Tian Wenshou , Zhang Jiankai
Published: February 2023

Using multi-model large-ensemble simulations from Polar Amplification Model Intercomparison Project (PAMIP), this study investigates the response of stratospheric polar vortex (SPV) to future sea-ice loss over Barents-Kara-Seas (BKS) and Sea of Okhotsk (SOK). On average across seven models, BKS sea-ice loss weakens the SPV during winter (November-February) through enhancing planetary wave-1, while SOK sea-ice loss strengthens the SPV in late winter and early spring (January-April) through weakening planetary wave-2. The weakened SPV induced by BKS sea-ice loss is more robust across models than the strengthened SPV induced by SOK sea-ice loss. Divergent magnitudes of SPV responses across models can be well explained by divergent planetary-scale wave responses to BKS sea-ice loss, but less so for SOK sea-ice loss. A linearized barotropic model yields similar planetary-wave responses to the PAMIP models and provides further evidence that local warming induced by sea-ice loss over the two regions modifies the near-surface wave source.
Exploring the relative contributions of fluid and solid phases in debris flow barrier impact
Authors: Hirsch Esme , Woods Joshua , Mulligan Ryan , Take Andy
Published: February 2023

Landslide barrier structures constructed on high-risk slopes are a useful strategy to halt and retain debris to protect vulnerable downslope infrastructure and inhabitations. To appropriately design these systems, an estimate of the likely volume, thickness, and velocity of the flow is required immediately prior to interaction with the barrier. These characteristics of the flow, when combined with an analytical model or numerical simulation of the impact, define the structural demand on the barrier. In this study, we use the large Queen’s University Landslide Flume to explore the relative contributions of the fluid and solid phases of a multi-phase flow on the structural demand on a barrier. Impact forces following dam break experiments of up to 1 m3 of material, released from the top of a 6.5 m long slope inclined at 30 degrees are explored for releases of pure water, dry granular particles, and fully-saturated granular water-grain mixtures. Impacting the barrier at approximately 4-5 m/s, temporal impact behaviour captured using ultrahigh speed imaging is correlated with the time series of impact load. Quantitative comparisons are then made between the observations of impact force by each class of flow to predictive equations published in the literature, highlighting the degree of match, hypotheses for observed discrepancies, and the relative contributions of the fluid and solid phases.
The effect of altered moisture availability on greenhouse gas emissions in sub-alpine peatlands in southern Australia
Authors: Wong Vanessa , Ferguson Rory , Moore Joslin
Published: February 2023

Peatlands store amongst the highest proportion of soil carbon in terrestrial ecosystems, but there is significant concern surrounding the effect climate change, and in particular, altered soil moisture regimes have on carbon cycling in these ecosystems. While greenhouse gas dynamics of boreal and high-elevation peatlands are well-studied in the northern hemisphere, less is known about peatlands in an Australian context. Soils were sampled from Lake Mountain, a sub-alpine peatland in south-eastern Australia at along a transect at four sites; sphagnum, wet peat, mid slope and woodland sites. The soils were incubated for 31 days to determine the effect of altered moisture content on CO2, CH4 and N2O fluxes under controlled conditions. Three moisture scenarios were assessed, a wet, dry and a 14-day wet-dry cycle examined over four sites, with three replicate cores per site. The Lake Mountain peatlands were estimated to store 114.52 Mg ha-1 in the top 20 cm, which is lower than other estimates of high elevation peatlands in south-eastern Australia. There was no effect of treatment on greenhouse gas fluxes, but higher carbon to nitrogen ratio was found to increase CO2 and CH4 fluxes. Some N2O sequestration was also identified. The results suggest that over the short term where soils do not dry out completely, site characteristics have a larger influence on GHG emissions compared to altered moisture availability.
Nonhydrostatic simulation of hyperpycnal river plumes on sloping continental shelves: Flow structures and nonhydrostatic effect
Authors: Chou Yi-Ju , Yeh Yi-Chun
Published: February 2023

We use the SUNTANS model to simulate plunging hyperpycnal plumes on different shelf slopes in idealized domains. Our simulations reveal detailed three-dimensional flow structures in both transient and steady states. An important flow feature is the formation of the triangular suspended sediment concentration pattern at the surface, which results in a flow convergence upon plunging and closely relates to the plume’s three-dimensional flow structure. As the slope is steeper, the triangular pattern becomes shorter in the cross-shore distance, resulting in stronger flow convergence. We show that the nonhydrostatic effect is particularly important before plunging, where the plume is subject to a significant change in the vertical direction. Moreover, the great fluctuations of the velocity field from the hydrostatic calculation result in a much higher eddy diffusivity compared with the nonhydrostatic case, leading to slower sink of the plume while plunging during the transient state. We also conduct depth-integration analysis of both the cross- and along-shore momentum components to examine the bulk effect of the shelf slope, the three-dimensional flow structure, and the nonhydrostatic pressure. We find that the flow convergence due to plunging of the plume provides strong lateral transport of the cross-shore velocity component toward the central line, which leads to the difference between three- and two-dimensional plumes. The flow becomes divergent when the plume forms an undercurrent, in which the lateral transport becomes an important momentum sink.
A hybrid deep learning framework for predicting point-level Alaskan fires
Authors: Seo Hocheol , Kim Yeonjoo
Published: February 2023

Fires in high latitudes are becoming more critical in terrestrial ecosystem modeling. With climate warming and dry weather condition, the fires have spread more, and widespread burning has severely damaged the ecosystem. As the fire dynamics cannot be described with the mass or energy balance equations, the fire models have been developed with different input variables, linked with different vegetation models, and widely coupled with the earth system models (ESMs) or land surface models (LSMs) with different complexities of parameterization. Here, we designed a new approach using hybrid deep learning [Long Short-Term Memory (LSTM) - Artificial Neural Network (ANN)] for predicting Alaskan natural fires and aimed to understand the impacts of fires with from the NCAR community land model 5 – biogeochemistry (CLM5-BGC). This study was conducted based on fire information provided by Alaska Interagency Coordination Center (AICC), which provides the data for each fire point, start date, end date, and total burned area from 2016-2020. As the fire duration was identified as the most important in predicting the burned area, we first trained the LSTM for predicting fire duration (i.e., fire ignition and fire persistence period) with ERA5 atmospheric forcings. Also, we trained ANN to predict the burned area with both ERA5 atmospheric forcings and fire duration. Then, we combined two models (LSTM and ANN) to simultaneously predict the fire days and burned area with climate and vegetation datasets. This hybrid model has the strength to capture large fires (>10000ha), comparing the burned area from CLM5-BGC (Correlation: 0.79). When this hybrid model is coupled with CLM5-BGC, we found that the carbon fluxes changed over Alaska. In particular, total net ecosystem exchange (NEE) increased by more than two times that of only CLM5-BGC, which could primarily affect terrestrial carbon exchanges.AcknowledgementThis work was supported by the Korea Polar Research Institute (KOPRI, PE22900) funded by the Ministry of Oceans and Fisheries and the Basic Science Research Program through the National Research Foundation of Korea, which was funded by the Ministry of Science, ICT & Future Planning (grant no. 2020R1A2C2007670) and by the Ministry of Education (2022R1A6A3A13073233).
Magnetotelluric investigation of the geothermal resources of South-West Ireland: DIG Project
Authors: Ye Tao , Duygu Kiyan , O’Reilly Brian , Meere Patrick , Hogg Colin , Fullea Javier , Bean Christopher , Lebedev Sergei , Chambers Emma , Rezaeifar Meysam , Tomar Gaurav , Scully Aisling ,   DIG team
Published: February 2023

The DIG (De-risking Ireland’s Geothermal Energy Potential) project aims to better understand Ireland’s low-enthalpy geothermal energy potential by integrating inter-disciplinary and multi-scale datasets (Kiyan et al., 2022; Chambers et al., 2022). One aim of the project is to evaluate the geothermal energy potential of the Upper Devonian Munster Basin within the Variscides of southern Ireland. A more specific objective is to focus on the Mallow warm springs area (MWSA) which is sited along the Killarney-Mallow Fault Zone (KMFZ).Two parallel magnetotelluric (MT) profiles have been deployed across the east-northeast trending KMFZ in the MWSA since November 2021 to directly image fault conduits and fluid aquifer sources at depth, within a convective/conductive region associated with the known occurrence of warm thermal springs. This will determine the scale of the geothermal anomaly and hence will evaluate the potential for local- and industrial-scale space heating in the local-scale survey locality.To eliminate the electromagnetic noise from the acquired MT time-series data, we have made efforts to improve the data quality by not only using the new generation Phoenix Geophysics MTU-5C systems but also processing these time-series data with two different processing software; (i.e., FFProc, an improved multivariate robust statistical data processing software (Castro et al., 2021) and EMPower, a commercial remote-reference software from Phoenix Geophysics).The 2-D inversion of these data reveals a striking vertical fault conductor zone (FCZ) extending to depths of at least 4 km beneath the KMFZ. The corresponding 3-D inversion model for these data along the two profiles further confirms the existence of the FCZ. Based on our preliminary results, we propose that the KMFZ is probably the main fault conduit associated with the Mallow warm springs area and the FCZ delineates the fluid pathways associated with the fault zone.
Reconstructing Martian Year 36 column dust optical depth maps using EMM/EMIRS and MRO/MCS
Authors: Montabone Luca , Kleinboehl Armin , Smith Michael , Edwards Christopher , Forget François , Kass David , Millour Ehouarn , Stcherbinine Aurélien
Published: February 2023

Montabone et al., 2015 and 2020, [1, 2] have developed an iterative, weighted, running mean methodology to grid the available retrievals of atmospheric column dust optical depth (CDOD) from multi-annual and multi-instrument spacecraft observations at Mars. The application of this methodology has produced daily gridded maps of CDOD from Martian Year (MY) 24 through 35, using Mars Global Surveyor/Thermal Emission Spectrometer and Mars Odyssey/Thermal Emission Imaging System nadir observations, as well as the estimates of this quantity from Mars Reconnaissance Orbiter/Mars Climate sounder (MRO/MCS) limb observations. Given the lack of dust observations at certain times and locations, the daily gridded maps have missing values at some grid points. Kriging spatial interpolation has been used to produce regular maps that are useful as multiannual dust scenarios for model simulations, and for the Mars Climate Database (MCD) statistics [3].We have now adapted this methodology to include CDOD retrievals from Emirates Mars Mission/Emirates Mars Infrared Spectrometer (EMM/EMIRS) nadir observations in MY 36 [4]. The specificity of EMIRS spatial and temporal coverage as well as the extended nature of its footprint are taken into account when carrying out the gridding. We will present a cross-comparison of maps obtained using only EMIRS retrievals and maps obtained using only MCS retrievals, in the attempt to understand what is the best approach to produce a MY 36 dust scenario that makes the best use of both instruments. We will particularly focus on the evolution of large-scale dust storms in MY 36.References: [1] Montabone, L., et al. (2015) Icarus 251, pp. 65-95, doi: 10.1016/j.icarus.2014.12.034 ; [2] Montabone, L., et al. (2020) J. Geophys. Res. - Planets, doi: 10.1029/2019JE006111 ; [3] http://www-mars.lmd.jussieu.fr (Publicly available dust gridded maps can be currently found up to MY 35 by clicking on the “climatologies of Martian atmospheric dust” link under “Martian dust Climatology”) ; [4] Smith, M.D., et al. (2022) Geophys. Res. Lett. 49, Issue 15, doi: 10.1029/2022GL09963
Combined Effects of Geological Heterogeneity and Discharge Events on Groundwater and Surface Water Mixing
Authors: Nogueira Guilherme , Partington Daniel , Fleckenstein Jan H.
Published: February 2023

Exchange between stream water (SW) and groundwater (GW) is an important mechanism controlling water quality in river-corridors. Different works have already recognized the complex interactions between hydrological and geological characteristics for SW-GW exchange fluxes (EF). However, it remains unclear how EF and subsequent SW-GW mixing are affected by different discharge events (e.g., peak discharge magnitude and event duration) that take place within different geological settings (e.g., highly permeable sand units juxtaposed to low permeable silt units). Here, to assess the combined effects of geological heterogeneity and discharge events on the EF patterns and subsequent SW-GW mixing in riparian aquifers, we combined a fully-coupled 3D numerical model with a mixing cell routine using 35 binary sedimentary geological settings (covering five different sand to silt ratios in the alluvial aquifer material) and eight different hydrological scenarios. Our results indicate that geological heterogeneity at the reach-scale has secondary effects on EF patterns and on the resulting net EF, mainly affecting the EF magnitudes. While EF magnitudes increased with increasing sand fractions (and hydraulic conductivity (K) values), including geological heterogeneity in the model generally enlarged SW infiltration, resulting in slightly higher net EF in comparison to the equivalent K homogenous cases. In general, SW-GW mixing under baseflow conditions decreased with increasing sand fractions. Furthermore, mixing was higher in the equivalent homogenous cases (e.g., similar K values) in comparison to the heterogeneous cases. On the other hand, the increase in SW-GW mixing due to discharge events was larger in sand units, as well as in the generated heterogeneous cases in comparison to their equivalent homogeneous cases. The results also indicated that more intense discharge events (higher peak discharge) promoted SW-GW mixing more than longer events presenting similar cumulative discharge values. Our work extends the knowledge on SW-GW mixing, critical for river restoration strategies and for downstream management of dam-regulated rivers, and sheds some light on potential future research direction in integrated SW-GW assessments and modelling.
Extreme agrometeorological events over Zimbabwe: Characteristics and drivers
Authors: Masukwedza Gibbon Innocent , Todd Martin , Lazenby Melissa , Boult Vicky
Published: February 2023

Dry and heat spells have the potential to alter the maize crop’s physiology and ultimately result in low yield. This study proposes a methodology of moving away from the generic dry spell definitions by using the water requirement satisfaction index (WRSI) output from the Tropical Applications of Meteorology using SATellite data – AgriculturaL Early waRning sysTem (TAMSAT-ALERT) as a metric of the impact such events have on the maize crop. We define these objectively identified events as impactful dry spells (IDS). The total exceedance of the maize crop’s upper-temperature optimal threshold is used to capture extreme temperatures during the growing season and is defined as impactful heat spells (IHS). Results of our analysis show that some seasons with relatively low yields were associated with the co-occurrence of severe IDS and IHS events specifically in the establishment and vegetative development phases. This implies that operational drought monitoring models with methodologies similar to that of TAMSAT-ALERT have the potential of inadvertently underestimating yield since they are incapable of incorporating the impact of heat on the crop’s physiology. We also investigate the rainfall characteristics based on the concept of Shannon entropy and show that seasons with relatively high (low) simulated yields are associated with (un)evenly distributed rainfall. Seasons of low simulated yield are shown to be associated with the southward displacement of Tropical Temperate Troughs; an anomalously weak (strong) Angola Low, Mascarene High-Pressure, and St. Helena High-Pressure systems (Mozambique Channel Trough and Botswana High), coupled with regional inhibitive atmospheric conditions for convective cloud development. This is the opposite of atmospheric patterns in seasons with a high simulated yield.
Modelling tectonic flow with discontinuous Galerkin level set method: Case studies and applications for the Neoarchean crustal dynamics
Authors: Wu Qihang , Lin Shoufa
Published: February 2023

We present a new numerical method to simulate the structural patterns emerging from the long-term large-deformation tectonic flows in both two and three spatial dimensions.  The domains of different material properties are each represented by a level set function discretized on a Eulerian mesh with the discontinuous Galerkin method. The level sets are advected by a velocity field provided by a coupled Stokes flow solver. Our method accurately captures the material interface by the adaptive mesh refinement, reduces the computational expenses compared to the traditional particle-in-cell method and offers straightforward handling of geometric splitting and merging.  Under the unified finite element framework, our method promises the flexibility in the choice of mesh geometry as well as the potential for extending to complex rheology.  With passive tracers geat and around areas of interest, the finite strain of the flow field can be integrated through any time interval within the total simulation time.  The strain ellipsoids thus obtained offers the possibility for ground-truthing the simulated deformation patterns with the field structural analysis.  Our results demonstrate identical physical behaviour when compared with established structural geology and geodynamic benchmarks.The style of the crustal dynamics on the Archean Earth has been subject to controversy on whether a vertical tectonic style in the form of Rayleigh-Taylor instability, induced by an inverted density profile, prevails in the early history of the Earth and if so, how the transition to the present-day plate tectonics, characterized by dominantly horizontal movement, is manifested in the rock record.  Equipped with our modelling scheme, we construct numerical models to simulate the lithological distributions and deformation patterns resulted from a synchronous operation of vertical tectonism and horizontal shearing. The latter can be viewed as a possible result of some far-field tectonic boundary condition (e.g. oblique convergence).  Many aspects of the simulation in terms of the map pattern, foliation/lineation trend and strain distribution compare favorably with the field observations in Neoarchean granitoid-greenstone terranes in the Superior Province as well as worldwide.  Therefore, it is concluded that the vertical and horizontal tectonism are not mutually exclusive tectonic regimes  The symbiosis of both tectonic processes is a viable mechanism for establishing the crustal architecture and the deformation pattern we see today in many Neoarchean terranes and might represent a transition from the former to the latter in the Neoarchean.