bluuebunny/crossref_metadata_2025 huggingface dataset:
Some Thoughts on Causal Inference, the Scientific Method, and Data Assimilation
Authors: Ghil Michael , Carrassi Alberto , de Viron Olivier
Published: March 2024

Causal inference is at the heart of the scientific method as usually practiced. Still, Karl Popper (The Logic of Scientific Discovery, 1935/1959)  tells us that a theory in the empirical sciences can never be proven: it can only be falsified, meaning that it can, and should, be scrutinized with decisive experiments. Even so, nobody that I know writes or publishes papers to disprove one’s own theory, only an opposing theory. And the debate rages on.At the heart of this session lies the question of whether, and how, one can prove, rather than just disprove, a causal link between phenomena in the empirical sciences. The session deals specifically with statistical, as opposed to dynamical methods. These methods have the advantage that they are essentially indifferent to any laws of, or other accumulated heuristic ideas on, the field to which they are being applied: whether the time series one considers are from the environmental sciences, biology or medicine does not matter, only their length and accuracy does.Judea Pearl (e.g., Stat. Surveys, 2009) made an important observation on how to transcend the saying that “Correlation is not causation” by pointing out that standard methods of statistical analysis rely on the stationarity hypothesis of the phenomena being examined. Crucial questions, however, like the causal role of anthropogenic forcing in climate change, deal precisely with the causes of nonstationarity. In particular, Pearl suggested counterfactual analysis as an essential approach in establishing criteria for the necessary and sufficient character of a given cause for a given phenomenon. Thus, the common approach of detection and attribution in the climate sciences only covers the sufficiency aspect of anthropogenic forcing, and more can be done (Hannart et al., BAMS, 2016; Clim. Change, 2016).The present talk will cover four specific aspects of these broad issues: (i) the distinction between information transfer, including both linear correlations and nonlinear extensions thereof, and true causation; (ii) the divergent results of some widely, and not so widely, used methods of studying information transfer (Krakovska et al., PRE, 2018; Kossakowski et al., Psychol. Methods, 2021; Delforge et al., HESS, 2022); (iii) shared variability of climatic time series (De Viron, GRL, 2013; ); and (iv) the uses of data assimilation in applying counterfactual theory to nonstationary phenomena (Carrassi, QJRMS, 2017; Metref et al., QJRMS, 2019).Conclusions will include the obvious one that statistical studies of causal inference have to be complemented by dynamical ones.
From Ice to Deep Water Fans: Seismic Geomorphology Reveals the Story of a Glacigenic Basin Floor Fan offshore West of Shetland
Authors: Caruso Simona , Maselli Vittorio , Rea Brice , Spagnolo Matteo
Published: March 2024

This study uses 3D seismic reflection data to conduct a detailed seismic geomorphology analysis of a portion of a glacigenic basin fan system located offshore West of Shetland in water depths greater than 1000 m.These deposits lie downslope from a gully system linked to the Foula wedge trough mouth fan, with both systems remarkably preserved at the present-day seafloor. While the seafloor morphology has received extensive attention in existing literature, the basin fan system subsurface structure, particularly its 3D geometry and distribution, remains less understood. This study lifts the veil, unveiling its basal surface and internal architecture in unprecedented detail. The 3D seismic characterisation reveals a complex basin channel network with linear, diverging erosional features and distinctive terminal lobes. These lobes exhibit stacked and backstepping patterns. The seismic geomorphology showcases features indicative of both debris flows and turbidites. This intricate interplay suggests a complex shelf-to-basin sediment transport and deposition mechanism.The integration of this newfound evidence with existing regional bathymetry, helped pinpoint the source of the main basin distributary channels to two of the downslope gullies.  This suggests that, initially, high energy flows remained somewhat confined within the basin area allowing erosion. These local-scale insights shed light on different sediment delivery processes and their impact on basin fans development. Ultimately, these findings contribute to a more comprehensive understanding of the Foula wedge large-scale dynamics, particularly the influence of meltwater pulses driven by paleo-morphology, substrate characteristics, and unique ice-sheet behaviour during the Pleistocene glaciations.
Deep learning methods for modeling infrasound transmission loss in the middle atmosphere
Authors: Janela Cameijo Alice , Le Pichon Alexis , Brissaud Quentin
Published: March 2024

Accurate modeling of infrasound transmission losses (TLs) is essential to assess the detection thresholds of the global International Monitoring System (IMS) infrasound network, quantify their spatial and temporal variations, and refine interpretations of signals generated by events of interest. Among the existing tools, the method based on parabolic equations resolution (PEs) enables TLs to be modeled finely, but its computational cost does not currently allow exploration of a large parameter space for real-time prediction, making it inapplicable for operational monitoring applications in the framework of the Comprehensive Test Ban Treaty (CTBT).To reduce computation times, Brissaud et al. (2022) explored the potential of convolutional neural networks (CNNs) trained on a large set of regionally simulated wavefields (>1000 km distance from the source) to predict TLs with an error of 5 dB compared to PE simulations with negligible computation times ( 0.05 s). However, this new method shows both larger errors in upwind conditions, especially at low frequencies, and causal issues with winds at large distances from the source affecting ground TLs close to the source.To reduce prediction errors, we introduce a new Deep Learning method, seeking to predict TLs from globally simulated effective sound velocity fields (>4000 km distance), based on a Convolutional Recurrent Neural Network (CRNN) capable of accounting the sequentiality of the propagation phenomenon. This tool can be used to compute global detectability maps of infrasound events in an operational context.
Case study of Water-Energy-Food Nexus management in Northwest China
Authors: Wang Xiaojun , Sun Jiaqi , Zhang Jianyun , Jiang Yanan
Published: March 2024

Water, energy, and food constitute essential resources crucial for human survival and development. Water security, energy security, and food security are critical issues related to human sustainable development. Northwest China is endowed with abundant energy and mineral resources. Simultaneously, the region serves as a significant reserve base for grain production in China. However, Northwest China faces challenges related to water scarcity. The rapid increase in water demand for energy development and agricultural production intensifies competition for water resources among food and energy. Water scarcity has emerged as a significant constraint on the development of the energy and food industries in the region. Given the interrelated, mutually restrictive, and interdependent nature of water, energy, and food, scientifically revealing and coordinating the Water-Energy-Food (WEF) interaction in Northwest China holds great scientific significance. To address this, we selected two cases in Northwest China: Ningdong Energy and Chemical Industry Base and Yulin City. Firstly, we proposed and developed an agent-based water–energy–food model based on MESA library for Ningdong Energy and Chemical Base. This model aims to simulate the complex dynamic interactions in the supply and demand process of WEF sectors under different scenarios. Secondly, for Yulin City, we constructed a Water-Energy-Food Integrated Management Model to deal with multiple Uncertainties, called IMMU-WEF model. This model was employed to explore the water resources allocation mode, agricultural planting structure, energy exploitation and production mode in Yulin City under uncertain conditions. Through the two cases, we aim to provide a valuable reference for the management of WEF nexus in Northwest China. This has significant implications for ensuring the sustainable economic and social development of Northwest China. Keywords: Water-energy-food nexus; multi-agent based modeling; IMMU-WEF model; Northwest China
On the use of probabilistic network models to assess spatially compound events in a warmer world
Authors: Graafland Catharina Elisabeth , Casanueva Ana , Manzanas Rodrigo , Gutierrez José Manuel
Published: March 2024

Probabilistic network models (PNMs) have established themselves as a data-driven modeling and machine learning prediction technique utilized across various disciplines, including climate analysis. Learning algorithms efficiently extract the underlying spatial dependency structure in a graph and a consistent probabilistic model from data (e.g. gridded reanalysis or climate model outputs for particular variables). The graph and probabilistic model together constitute a truly probabilistic backbone of the system underlying the data. The complex dependency structure between the variables in the dataset is encoded using both pairwise and conditional dependencies and can be explored and characterized using network and probabilistic metrics. When applied to climate data, PNMs have been demonstrated to faithfully uncover the various long‐range teleconnections relevant in temperature datasets, in particular those emerging in El Niño periods (Graafland, 2020).The combination of multiple climate drivers and/or hazards that contribute to societal or environmental risk are the so-called compound weather and climate events. These compound events can be the result of a combination of factors over different dimensions: temporal, spatial, multi-variable, etc. (Zscheischler et al. 2020). In particular, spatially compound events take place when hazards in multiple connected locations cause an aggregated impact. In this work we apply PNMs to extract and characterize most essential spatial dependencies of compound events resulting from concurrent temperature and precipitation hazards, either in the same location or spatially connected, which can be relevant for agriculture. Furthermore, PNMs are used to propagate evidence of different levels of observed and projected global warming to assess the possible evolution of compound events in a changing climate.ReferencesGraafland, C.E., Gutiérrez, J.M., López, J.M. et al. The probabilistic backbone of data-driven complex networks: an example in climate. Sci Rep 10, 11484 (2020). DOI: 10.1038/s41598-020-67970-yZscheischler, J., Martius, O., Westra, S. et al.  (2020). A typology of compound weather and climate events. Nat Rev Earth Environ 1, 333–347, doi: 10.1038/s43017-020-0060-z.AcknowledgementThis work is part of Project COMPOUND (TED2021-131334A-I00) funded by MCIN/AEI/10.13039/501100011033 and by the European Union NextGenerationEU/PRTR. 
Synergy in art-science collaborations: Finding a common language to convey ocean research through art
Authors: Ryan Svenja , Ummenhofer Caroline C. , Ehrens Deb , Xu Hong , Megathlin Linda , Getsinger Meghan
Published: March 2024

The ocean is at the heart of our climate system and understanding its role as a driver and modulator is critical in times of a changing climate, posing serious threats to our ecosystem and societies. This increases the need to communicate science in novel ways. Here we present outcomes, lessons-learned and future plans of artist-scientist collaborations as part of the Synergy II project – a collaboration between the Art League Rhode Island and the Woods Hole Oceanographic Institution. Self-selected pairs of scientists and artists collaborate with the goal to create a ‘common language’ using the arts to illustrate and communicate science. Through extensive conversations we examined the scientific and artistic process, and were surprised and delighted at the similarity of so many aspects of our work. We spoke in-depth about the challenges of communicating big ideas and numbers in meaningful ways and how we all had to be compelling storytellers. Produced artwork comprises a set of 3D kinetic sculptures created out of printed canvas, introducing the audience to a warming ocean and impacts of extreme temperatures on ecosystems and society more broadly. While the form captures the constantly moving and swirling motions of the ocean, the printed layers on the canvas also aim to convey the thrill of discovery and the complexity of our research, from data acquisition (now and in the past), coding to visualization and ultimately conveying a message. Other artwork highlights the role of ocean salinity in digitally layered 2D prints, capturing the central, yet underappreciated, role of the oceans for the global water cycle and ocean dynamics: the artwork conveys salinity as a critical metric tracking moisture export at the ocean’s surface, as well as different water masses being defined by different temperature and salinity compositions – and how new salinity sensing capabilities from space provide new insights into ocean dynamics and predictive capabilities for rainfall on land. As new collaborations begin, we strive to learn from our past experiences and venture into new exciting art projects that come together with existing artwork under the umbrella of Synergy II and expand on community engagement and outreach to involve K-12 education. These collaborations have added a new enriching dimension to all our work, both scientifically and artistically.
Vertical features of the ionospheric holes during rocket launches observed by the Sanya Incoherent Scattering Radar
Authors: Ding Feng , Yue Xinan , Cai Yihui , Wang Junyi , Zhao Linxuan
Published: March 2024

Previous observations shows that during rocket launches, the water in the plume released by rockets usually caused a wide range of ionosphere electron density depletion. While a number of publications devoted to the horizontal variations of such ionosphere holes, observation of the vertical features of ionosphere holes has seldom been reported. In this paper, we used the Sanya Incoherent Scattering Radar (SYISR) to observe the vertical variations of the ionosphere hole during two rocket launch events in year 2022. Both the rockets passed through the topside ionosphere over the China South Sea, with an estimated minimum distance of ~100-300 km from SYISR. About ~15 min after the rocket launch, we observed the ionosphere hole with an altitude range of ~200-800 km. The maximum electron density depletion of -20% occurred at ~420 km, with a duration of 2.2 hours. Based on the observations, we discussed the diffusion of water molecules and its influences on altitude distribution of the ionosphere holes during the rocket launches.
Advances in hydrogeological knowledge of the island of El Hierro (Canary islands) through the construction of a 3D geological model
Authors: Baquedano-Estévez Carlos , Marazuela Miguel Ángel , Martínez-León Jorge , Cruz-Pérez Noelia , Hernández-Gutiérrez Luis Enrique , Santamarta Juan Carlos , de La Losa Almudena , García-Gil Alejandro
Published: March 2024

Due to the critical importance of groundwater in the Canary Islands, it is essential to understand and properly manage the water resources of these regions. Modelling of aquifer systems now provides valuable geoscientific information for their identification, protection and sustainable use. By means of a geological modelling procedure, using the GeoModeller programme, the first 3D geological model of the volcanic island of El Hierro has been produced. The 3D model was created from the Digital Terrain Model, geological maps, geological sections and lithological data from hydraulic works. Eleven formations covering the entire island have been identified, allowing the description and interpretation of the main hydrogeological units and known geological structures relevant to the regional scale. This 3D geological model will serve as the basis for developing, using the FEFLOW code, the first hydrogeological and geothermal model of the island, allowing progress to be made in the sustainability of the island's aquifers.
Bottom-up approach to estimate the present and future air emissions under different policy scenarios in Tier-2 non-attainment city in India
Authors: Sharma Manuj , Jain Suresh
Published: March 2024

Air quality degradation in Tier 2 non-attainment Indian cities is a rising concern as the air pollution level is alarmingly increasing, similar to metropolitan cities. Efficient urban air quality management measures in Tier 2 non-attainment cities require a comprehensive emission inventory to support the air pollution abatement strategies. The present study developed a detailed emission inventory of the primary criteria pollutants (PM10, PM2.5, SO2, NOx, CO) and NMVOCs accounting for all the urban anthropogenic sources. The bottom-up emission estimate technique was applied to the Vijayawada metropolitan region, one of India's most polluted tier 2 cities. The emission load of PM10, PM2.5, SO2, NOx, CO, and NMVOCs over Vijayawada were estimated to be 5.65 Gg, 2.13 Gg, 1.38 Gg, 8.91 Gg, 17.17 Gg, and 2.33 Gg respectively in 2021. Road and construction dust accounted for 74% of PM10 and 45% of PM2.5, whereas active motorized vehicular activities significantly contributed to CO (78%) and NOx emissions (69%), and the industrial sector accounted for 96% of the overall SO2 emission load across Vijayawada.Further, various strategies were tested to project the emission load of PM10, PM2.5, SO2, and NOx under the Business as Usual (BAU) and Alternative (ALT) scenarios for 2025 and 2030, respectively, to evaluate the increased and reduced emission potential. Under the BAU scenarios, the key factors for future projections of sectoral activity data are the population and economic growth of Vijayawada. The BAU scenarios indicated an overall emission increase of 12% and 36% in PM10, 4% and 22% in PM2.5, and 5% and 11% in SO2, whereas the overall NOx emissions are estimated to be reduced by 13% and 14% in 2025 and 2030 respectively. Introducing the BSVI emission standards and phasing out older vehicles were the key scenarios for reducing NOx emissions under BAU scenarios. The strategies tested under the ALT scenarios considered the multi-sectoral control actions declared or proposed by national and state governments owing to the potential to reduce air pollution in the study area. Advanced control techniques, coupled with shifting towards cleaner fuels, may show the potential to reduce the overall PM10 emissions by 13% and 15%, PM2.5 by 16% and 23%, SO2 by 24% and 48%, and NOx emission by 20% and 32% in 2025 and 2030 respectively, under ALT scenarios. The study findings provide a comprehensive emission database encompassing pollutants, sources, and area-specific quantitative information for Tier 2 non-attainment cities. The research outcome will also be used as the guiding tool by the scientific community, air quality researchers, and policymakers for designing practical and feasible air pollution abatement strategies and management plans to provide clean air for present and future generations at the city level.Keywords: Emission Inventory, Scenarios development, Urban anthropogenic sources, Mitigation measures, Non-attainment cities
Variation in Fe2+ / Fe3+ in hydrous silicates in subducted oceanic crust
Authors: Whitney Donna , Hanel Sara , Wilke Max , Rosa Angelika
Published: March 2024

A fundamental observation regarding oceanic subduction systems is that the starting material of subduction (MORB) is less oxidized than a major end-product (primitive magma in arcs), likely as a result of infiltration of mantle source regions by oxidized components from the subducted slab. Important redox-sensitive elements in slabs are S, C, H, and transition elements such as Fe and Mn. Fe is important because it is volumetrically significant, and release of other redox agents by dehydration reactions in subducted altered oceanic crust is controlled in part by Fe3+/∑Fe. Lawsonite (Lws) and epidote-group minerals (EGMs) are hydrous Ca-Al silicates that are key phases in subduction-zone H2O and element cycling owing to their composition and abundance, and the Lws-EGM transition has been linked to significant changes in fluid composition. Fe is a major component in most EGMs and a more minor but common component in Lws. Fe in Lws and metamorphic EGMs is generally assumed to be entirely Fe3+ that substitutes for Al in octahedral sites. However, results of Fe-XANES analyses for Lws and EGMs in blueschist and eclogite were acquired at the European Synchrotron Radiation Facility and show a wide range of Fe3+/∑Fe. Results for Lws appear robust because there are no signs of beam damage during analysis and there does not appear to be a strong orientation effect (linear dichroism). EGMs similarly show no beam damage effects but, in contrast to Lws, show significant variation in XANES spectra and resulting calculated Fe3+/∑Fe as a function of orientation. Although Fe in some Lws analyzed is entirely Fe3+, Lws and EGMs from New Caledonia blueschists contain substantial Fe2+. Work is in progress to determine what controls Fe3+/∑Fe in Lws and EGMs, but a preliminary conclusion is that Fe2+ in these phases in subducted oceanic crust may be greater than currently known, with implications for phase equilibria calculations and understanding of subduction redox conditions and processes.
Bioeconomy gaps and opportunities in restored Atlantic forests
Authors: Krainovic Pedro , Paulo Romanelli João , Helena Porcari Simões Laura , Rodrigues Souza Lukas , Brower Rens , Flávia Boeni Ana , G. Massi Klécia , A. P. Toledo Cássio , R. Rodrigues Ricardo , C. Souza Vinicius , B. Chaves Rafael , de-Miguel8 Sergio , H. S. Brancalion Pedro
Published: March 2024

Forest restoration faces persistent challenges for its financial viability due to high land opportunity costs and insufficient financial returns from restored areas, such as through payments for ecosystem services and timber production. A potential financial pathway is to develop non-timber forest products with bioeconomic potential. Here, we explore the bioeconomic potential of native tree species growing in different types of new wooded lands in Atlantic forests. First, we established 25 30 𝚡 30 m plots in natural regeneration, degraded forest remnants, and actively managed areas (eucalyptus monoculture and active restoration) in the Paraíba Valley, southeastern Brazil, where we sampled all woody individuals with dbh ≥ 5 cm, totaling 284 native tree species. Then, we conducted a literature review and patent survey on the biotechnological potential of the species sampled. Based on this review and survey, we calculated the proportion of sampled species with patents and assessed the species used and general characteristics of patents registered among prominent companies in the market. We found 168 (70%) species with a biotechnological potential based on the presence/absence of articles reporting uses for medicine, cosmetics, food, and other market segments, such as bioinsecticides, bio fertilization, construction, and manufacturing. In the sampled areas, species offer varied potential for use, with higher potential in spontaneous environments. Araucaria angustifolia was the most extensively studied species, with 246 research papers, followed by Euterpe edulis (205), Baccharis dracunculifolia (188), Dodonaea viscosa (170), Cedrela odorata (158), Copaifera langsdorffii (139) and Hymenaea courbaril (132). We found patents worldwide, distributed across more than 20 countries, for the sampled species. The medicinal use of leaf chemicals accounts for the largest use in our survey. Despite these numbers, we found that less than 5% of the investigated articles reported evaluations of final products, while most provided results from in vitro, in vivo, or chemical analytics descriptions. Most patents registered by companies are related to exotic and non-tree species, many associated with existing commodity chains, reinforcing the need to integrate bioeconomy and forest restoration agendas better.
Using In Situ Airborne Measurements to Evaluate Pandora Ground-based Remote Sensing Formaldehyde Data Products
Authors: St. Clair Jason , Wolfe Glenn , Hanisco Thomas
Published: March 2024

Measurements of boundary layer formaldehyde (HCHO) are valuable for air quality monitoring, both because HCHO is classified as an air toxic by the US EPA and because HCHO concentrations directly reflect recent VOC oxidation and therefore are a diagnostic for ozone production. The Pandora network, with instruments deployed across the US and around the world, is a promising source of boundary layer HCHO data but previous evaluation of Pandora HCHO data was limited to total column HCHO at two sites during one campaign. Here we extend the evaluation to include Pandora tropospheric column and profiling data products derived from differential optical absorption spectroscopy (DOAS) operation. NASA’s SARP-East program provided a unique opportunity to evaluate the Pandora DOAS data products with profiling spirals by an airborne in situ payload that included the NASA Goddard CAFE HCHO instrument. Comparison of CAFE and Pandora data will be presented with the goal of better informing the Pandora data community of its performance.
Tweedsmuir Glacier, Alsek River, and the salmon migration that wasn’t
Authors: Shugar Dan , Flowers Gwenn , Cronmiller Derek , Mingo Laurent , von Finster Al , Sharp Meghan
Published: March 2024

Sockeye salmon are an important species both ecologically as well as culturally. At some point in the recent geological past, as substantiated by Indigenous oral history and ecological data, sockeye would migrate up Alsek River through the St Elias Mountains into southwest Yukon. But they no longer do so, and river-blocking surges of Nàłùdäy (Lowell Glacier), which translates to ‘Fish Stop’, have been blamed. During multiple surges over the past few thousand years, Nàłùdäy impounded massive glacial lakes, which drained catastrophically and transported vast quantities of gravel and boulders downstream. Although Nàłùdäy has not blocked Alsek River since the late 1800s, sockeye have yet to recolonize this stretch of the river. In this study, we suggest a recent advance of Tweedsmuir Glacier, about 65 km downstream of Nàłùdäy, caused Alsek River to carve the narrow Turnback Canyon into bedrock. This canyon, which stretches for ~10 km along the glacier’s terminus and in places is only a few metres wide, produces a functionally insurmountable velocity barrier to upstream fish migration. The ultimate goal of the study is to determine whether Alsek River was rerouted in the recent geological past, cutting off the sockeye salmon migration. Our specific objectives are to (1) determine whether an ancestral paleochannel of Alsek River exists beneath Tweedsmuir Glacier; (2) establish the chronology of canyon incision and determine whether it was related to rapid drainage of ice-dammed lakes at Nàłùdäy; and (3) evaluate whether the subglacial topography may be conducive to Alsek River abandoning Turnback Canyon as the glacier retreats, creating a gentler stretch of river allowing fish to reach upstream habitat. Between 2019 and 2022, we collected more than 450 line-km of airborne and ground-based ice-penetrating radar data over the lower glacier to map the subglacial topography with the intent of determining whether a paleochannel might exist up which sockeye may have traveled prior to Neoglacial advances. Results suggest that the terminal lobe of Tweedsmuir Glacier is up to ~500 m thick and in some places the bed is up to ~100 m below sea level. Based on preliminary analyses of the radar data, it is conceivable that Alsek River could abandon Turnback Canyon for the lower elevation terrain, as the glacier retreats in the coming decades and centuries. Terrestrial cosmogenic nuclide dating of the canyon walls using 36Cl suggests that the canyon was cut within the last thousand years, and very quickly, possibly in a single episode of downcutting.
Impact of Capillary Number, Fluid Viscosity Ratio, and Fracture Closure on Two-Phase Flow Regimes in Geological Fractures: An Experimental Study
Authors: Rezaei Amin , Gomez Francesco , Borgman Oshri , Neuweiler Insa , Meheust Yves
Published: March 2024

Accurately predicting fluid-fluid interface displacement in fractured reservoirs is paramount for optimizing subsurface operations, particularly in the context of enhanced oil recovery and geological carbon sequestration (GCS). However, a comprehensive understanding of two-phase flow behavior in fractures, including the impact of fracture closure, fluid viscosity ratio, and capillary number, is yet to be achieved. To address this challenge, we have developed an analog experimental setup to investigate the intricate relationship between fracture surface roughness and fluid-fluid interface displacement. Our experimental setup features a transparent fracture flow cell with self-affine rough-walled surfaces that are matched to each other above a chosen length scale (denoted below as the correlation length) and a precisely controlled mean aperture. Realistic synthetic fracture geometries were generated numerically. They are characterized by their Hurst exponent, fracture closure, and correlation length. High-speed imaging captures the dynamic spatial distribution of fluid phases within the fracture plane during drainage processes in a given fracture geometry. The mean aperture can be varied between experiments for a given geometry of the fracture walls. We investigate a comprehensive range of capillary numbers, spanning both viscous and capillary-dominated regimes, vary viscosity ratios, and characterize the resulting displacement regimes. Our results reveal a profound impact of fracture closure and correlation length on trapping efficacy, particularly in the capillary-dominated regime. These findings can be interpreted in terms of residual trapping of CO2 during GCS in fractured reservoirs.
A framework for setting soil health targets and thresholds in agricultural soils 
Authors: Matson Amanda , Fantappiè Maria , Campbell Grant A. , Miranda-Vélez Jorge F. , Faber Jack H. , Gomes Lucas Carvalho , Hessel Rudi , Lana Marcos , Mocali Stefano , Smith Pete , Robinson David , Bispo Antonio , van Egmond Fenny , Keesstra Saskia , Saby Nicolas P.A. , Smreczak Bozena , Froger Claire , Suleymanov Azamat , Chenu Claire
Published: March 2024

Soil health is a key concept in worldwide efforts to reverse soil degradation, but to be used as a tool to improve soils, it must be definable at a policy level and quantifiable in some way. Soil indicators can be used to define soil health and quantify the degree to which soils fulfil expected functions. Indicators are assessed using target and/or threshold values, which define achievable levels of the indicators or associated soil functions. However, defining robust targets and thresholds is not a trivial task, as they should account for differences in soil type, climate, land-use, management, and history, among other factors.We assessed (through theory and stakeholder feedback) four approaches to setting targets and thresholds: fixed values based on research, fixed proportions of natural reference values, values based on the existing range (e.g. lower quartile of the observed distribution), and targets based on relative change (e.g. a 20% increase of the indicator’s value). Three approaches (not including relative change) were then further explored using case study examples from Denmark, Italy, and France, which highlighted key strengths and weaknesses of each approach. Here, we present a selection of the assessment and case study results, as well as a framework, which facilitates both choosing the most appropriate target/threshold method for a given context, and using targets/thresholds to trigger follow-up actions to promote soil health.  
Using Pandora direct sun and MAX-DOAS formaldehyde columns for evaluating satellite retrievals
Authors: Pandey Apoorva , Place Bryan , Liao Jin , Abuhassan Nader , Cede Alexander , Hanisco Thomas , Lind Elena
Published: March 2024

Atmospheric formaldehyde (HCHO) is a short-lived but ubiquitous product of hydrocarbon oxidation. It is a tracer of hydrocarbon emissions and reactivity. HCHO has been observed from satellite-based instruments for over two decades. Retrievals typically involve (1) fitting slant columns to the observed UV/IR radiances and (2) deriving vertical columns from the slant columns using air mass factors. Air mass factors are calculated using radiative modeling and a-priori vertical HCHO distributions from a chemical transport model. The Pandora instruments form a ground-based remote sensing network that is valuable for validating satellite retievals. Pandora provides total and tropospheric columns of HCHO via direct sun (DS) and Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations in the UV, respectively. Here, we discuss conversion of slant columns to vertical columns for DS and MAX-DOAS Pandora measurements, neither of which involves radiative modeling and a-priori assumptions. We intercompare daily and seasonal variations in Pandora HCHO columns from these two distinct measurement techniques for ‘hotspot’ and ‘background’ sites to demonstrate their robustness and complementary strengths, as well as to estimate their uncertainties. We further examine the inter-site and seasonal variability in satellite (e.g., OMI, OMPS) retrievals relative to Pandora HCHO columns.     
A new metric for assessing planetary surface habitability
Authors: Woodward Hannah , Rushby Andrew , Crawford Ian , Mayne Nathan
Published: March 2024

Planetary surface habitability has so far been, in the main, considered in its entirety. The increasing popularity of 3-D modelling studies of planetary climate has highlighted the need for a new measure of surface habitability. Combining known thermal limits of Earth-based life with surface water fluxes, we introduce such a measure which can be calculated from the climatological output from general circulation model simulations. In particular, we pay attention to not only 'complex' life, but additionally the temperature limits of microbial and extremophilic life which have been vital to the generation of Earth's own biosignatures. This new metric is validated on Earth using ERA5 reanalysis data along with multiple datasets representing Earth-based life, as well as compared to the patterns of habitability of a model ensemble simulating an aquaplanet-Earth.
CS4Rivers: a transdisciplinary approach for monitoring freshwater habitats and their biodiversity.
Authors: Polvani Alessio , Vitillo Chiara , Gumiero Bruna , Galgani Luisa , Di Grazia Francesco , Sanna Venere Stefania , Loppi Stefano , Monaci Fabrizio , Capineri Cristina , Loiselle Steven Arthur
Published: March 2024

Freshwater ecosystems are crucial for life on our planet. These habitats are home to 10% of all known species, including a third of all vertebrates. In the last decades, most of the world’s freshwater ecosystems have suffered dramatic changes and negative impacts mainly due to anthropological activities and global warming. The assessment of riverine habitats quality could be helpful to preserve (or restore) freshwater ecosystems and to counteract biodiversity loss as well. Citizen Science is increasingly adopted in environmental monitoring projects. The increase in spatial and temporal resolution is just one of the strength points of participative projects: these can provide additional data for research purposes and monitoring agencies. In this context, a new CS-based research project called CS4Rivers has been created by the University of Siena and developed within the NBFC - National Biodiversity Future Center. CS4Rivers aims to monitor the biodiversity and the river habitats quality by using a transdisciplinary approach. During the project, several monitoring activities will be carried out: the freshwater chemical quality, the riparian vegetation, the macroinvertebrates, and the biodiversity target species in the fluvial corridor. For each activity, ad hoc sampling and monitoring protocols have been developed. Monitoring activities will be held on the Ombone River and its tributaries (Siena and Grosseto provinces, Tuscany, Italy). The project will last until December 2025. A pilot project has been already launched on the Idice River (Emilia-Romagna region, Italy). Future perspectives of this project will regard the export in national and international context of the transdisciplinary approach adopted in CS4Rivers.
Quantifying the role of interactive chemistry on the anthropogenic effective radiative forcing in Earth System Models
Authors: Mulcahy Jane , Cussac Martin , Olivie Dirk , Nabat Pierre , Michou Martine , Lathiere Juliette
Published: March 2024

Many global climate and Earth system models that participated in CMIP6 did not include fully interactive chemistry mechanisms mainly due to the large associated computational cost of these schemes. A number of studies have recently highlighted the potential importance of enhanced aerosol-chemistry-climate coupling and associated feedbacks for the anthropogenic effective radiative forcing (ERF) of a number of key climate forcing agents such as aerosols (Thornhill et al., 2021), methane (O’Connor et al., 2022) and ozone. The different levels of complexity in both aerosol and chemistry schemes in CMIP6 models has been highlighted as a leading contributor to the large inter-model diversity in the ERF of aerosols and trace gas species (Thornhill et al., 2021). To this end, as part of the EU Horizon project, ESM2025, advanced stratospheric-tropospheric chemistry schemes have been developed and implemented in 2 ESMs, CNRM-ESM and NorESM2, for the first time. Dedicated experiments have been conducted to determine the pre-industrial (1850) to present-day (2014) ERF with these updated models and the UKESM1.1 model, to assess the impact of fully interactive chemistry on the ERF of key forcing agents. In UKESM1.1, which already includes interactive chemistry, the interactive chemistry scheme is switched off and run with a much-simplified aerosol-chemistry mechanism driven by prescribed oxidant fields. We argue the improved realism of representing these aerosol-chemistry-climate interactions is essential for improved cross-model consensus on the magnitude of anthropogenic ERFs of aerosol and key trace gas species.References:Thornhill et al., Effective radiative forcing from emissions of reactive gases and aerosols – a multi-model comparison, Atmos. Chem. Phys., 21, 853–874, https://doi.org/10.5194/acp-21-853-2021, 2021.O’Connor et al., Apportionment of the pre-industrial to present-day climate forcing by methane using UKESM1: The role of the cloud radiative effect. Journal of Advances in Modeling Earth Systems, 14, e2022MS002991. https://doi.org/10.1029/2022MS002991, 2022.
Understanding the moisture source of orbitally controlled changes in northern Sahara rainfall: a multi-proxy speleothem approach
Authors: Lone Mahjoor , Rogerson Michael , Hoffmann Dirk , Luetscher Marc , Spötl Christoph , Mansoura Moez , Kallel Nejib , Elmejdoub Noureddine , Dublyanski Yury
Published: March 2024

The Sahara, the largest hot desert in the world, has witnessed green, humid phases in the past. It is clear that large areas of what is now arid/hyper-arid desert became vegetated, that currently fossil rivers flowed sufficiently to reach the Mediterranean, and that the African Monsoon is key in regulating this variance on the southern margin of the desert. However, what is happening on the northern margin, what regulates those changes and how the different northern and southern rainfall systems combine to affect the interior of the Saraha are poorly known. Closing this knowledge gap is an urgent priority, because climate models predict an enhanced drying under future global warming, but the IPCC give this forecast only “Medium” confidence and it contrasts strongly with those paleoclimatic records which indicate a greener Sahara during the warmer times through the Pleistocene. So, to understand what controlled the northern Sahara in the past, we use a multi-proxy approach using the longest absolute-dated speleothem records from Tunisia in central North Africa. This unique resource allows us to decipher periods of significant rainfall in this region through isotopic measurements and a direct indication of possible moisture sources through fluid inclusions.The records indicate a strong orbital control on past hydroclimatic changes suggesting enhanced rainfall during MIS 3, 5, 7 and 9. The fluid inclusions are consistent with a Western Mediterranean source for most rainfall, with some derived from the Atlantic. For much of the record, deuterium excess is highest in the samples with the most depleted d18O and d2H, which is consistent with some rainfall being derived from Mediterranean-derived high-intensity events, analogous to modern “medicanes”. High deuterium excess is also found during MIS5e, which is the only time the fluid inclusions we report from Tunisia are similar in composition to those we have already published for Libya, indicating an enhanced Eastern Mediterranean source occurred during the Eemian which is not reflected during other times of MIS5.
Generation of spatial grids for hydrometeorological data for estimation of groundwater recharge in tropical aquifers
Authors: Donado Leonardo David , Mercado Omar
Published: March 2024

Climatology and hydrology depend significantly on the precise spatial characterization of their variables on continuous surfaces. The interpolation of hydrometeorological data emerges as an essential component, allowing for the estimation of values between observation points and facilitating the creation of detailed and comprehensive datasets. This process is crucial for understanding the climatic and hydrological conditions of watersheds. This work describes applying a methodology for the spatial estimation of meteorological variables through geospatial models.The methodology includes data cleansing and validation to identify and correct outliers or errors, the assessment of model accuracy through cross-validation techniques, and a detailed analysis of the spatial and temporal variability of the data based on data availability in hydrometeorological stations.A geostatistical analysis is conducted, adapted to the peculiarities of each measured hydrometeorological variable, considering relationships with other meteorological variables and secondary information such as altitude, latitude, longitude, and terrain aspect, using multivariable regressions. This improved the data estimation quality due to high correlations between variables.The generation of data grids and their subsequent interpolation allow the creation of detailed maps of hydrometeorological variables in areas without monitoring stations, providing a more comprehensive and detailed view of environmental conditions. The uncertainty associated with the results is evaluated and presented to interpret the generated maps properly.This study, conducted in a Colombian watershed, highlights the applicability of this methodology in basins with limited information. For this purpose, data and maps of temperature, evapotranspiration, and precipitation were generated at different space-time scales of interest, in addition to estimating multi-temporal potential recharge maps.
Using small-magnitude earthquakes to investigate the interplay between seismic and aseismic deformation along the Hellenic Subduction System
Authors: Essing David , Cökerim Kaan , Bocchini Gian Maria , Harrington Rebecca M.
Published: March 2024

The Hellenic Subduction System (HSS) in the eastern Mediterranean is the oldest active subduction margin on earth. It is a segmented boundary that hosts the continuum of faulting styles over a ~200km range in depth and can generate large earthquakes with high tsunamigenic potential.  The complexity of deformation styles and rates leave key aspects of the system poorly understood. For example, historical records of Mw
Hydrogeological vigilance in the Eternal City: Insights from the development and strengthening of Rome's groundwater monitoring network
Authors: La Vigna Francesco , Papiccio Claudio , Roma Mauro , Gafà Rossella Maria , Martarelli Lucio , Silvi Angelantonio , Vitale Valerio , Monti Gennaro Maria , Congi Maria Pia , Bonfà Isidoro
Published: March 2024

The Groundwater Monitoring Network of Rome (GMNR) was born on 2014 when the Environmental Protection Department of Roma Capitale (Municipality of Rome) decided to dedicate the more than 200 existing water wells (mainly developed for green areas irrigation) also for monitoring purposes. The GMNR considerably contributed to the development of the new Hydrogeological Map of Rome on 2015. Recently, by an agreement between Roma Capitale and ISPRA (Geological Survey of Italy) the monitoring activities have been strengthen, several new wells have been surveyed and all data are inserted and are available in a web-GIS system and an interactive map.Each monitoring station visible on the interactive map have a link to a graph showing the trend over time of the measured parameters. In this regard, a system has been developed in order to allow the collection and the entry to the central database of investigated data even in real time by means of portable devices (tablet or smartphone), through a survey form. As a whole, this actually allow the field workers to quickly transmit the measured data - piezometric levels and in situ chemical-physical parameters - from the hydrogeological data collection site to a single online central database.Moreover, recently, thanks to the CARG project (National Geological and Geothematic Cartography), several probes are going to be purchased and to be installed in a selection of the monitoring stations, contributing to the real time data sharing.With the described agreement related to the GMNR, the survey activities are going to lead to a systematic structuring of information relating to the groundwater of the city of Rome, probably developing the first dedicated urban example in Italy, and contributing to enhance the local groundwater resource knowledge and also to increase public awareness in this regard.
Understanding the Drivers of Desertification and Land Degradation (DLD) over the Central Highlands of India
Authors: Mahato Trinath , Kumar Manish
Published: March 2024

Desertification is a worldwide issue receiving broad attention due to deforestation, climate change, and land abuse. In India, nearly 81.4 million ha are undergoing the desertification process. A long-term assessment of the key drivers of desertification and land degradation (DLD) was done over the state of Jharkhand in the central highlands of India. The region is highly vulnerable to desertification and land degradation due to its unique geographical and climatic features, with 68.77% (5.48 Mha) of the total geographical area of 7.97 Mha undergoing DLD. This study aims to quantify desertification in Jharkhand using various satellite imageries and supervised classification using machine learning (ML) techniques. The results showed five distinct classes of DLD cases, i.e., severe, intense, moderate, light, and no desertification. The severe and intense class areas make up about 5.11 Mha (64.43%) of the total geographic area (TGA). The moderate and light classes of DLD make up 0.93 Mha (11.79%) and 1.40 Mha (17.73%) of TGA, respectively. Remarkably, the districts of Giridih, Gumla, Ranchi, Dumka, Jamtara, Deoghar, Garhwa, and Palamu are considered to be the most prone regions to DLD. This study will help to demonstrate the application of remote sensing techniques to quantify DLD-prone regions and severity over the regions, which can help policymakers manage the local administrative bodies and state government departments to demarcate the region to continuously monitor and lay policies to tackle desertification.Keywords: Desertification, Central Highlands, GEE, Random Forest, Vulnerability, Machine Learning