bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow rule for unsteady flows of spherical and non-spherical grains down rough inclined planes
Authors: Wu Yanbin , Guo Zixiao , Pähtz Thomas , He Zhiguo
Published: March 2024

Based on laboratory experiments, Pouliquen (1999) uncovered a universal scaling law for the average velocity v of homogeneous flows of spherical grains down rough inclines [1]: , where g is the gravitational acceleration, h the flow thickness, and hs(θ) the thickness below which the flow stops depending on the inclination angle θ. Today, this so-called “flow rule” is well established in the field and has served as a critical test for continuum granular flow models [2]. However, based on more accurate measurements for granular materials composed of either spherical or non-spherical grains, Börzsönyi and Ecke (2007) found and pointed out that this revised flow rule was predicted by a two-dimensional granular kinetic theory [3, 4]. In addition, for non-spherical grains, they noticed deviations from this rule at large h/hs. Both Pouliquen and Börzsönyi and Ecke assumed that the granular flows in their experiments were steady.Here, we report on new systematic experiments for granular materials composed of spherical glass beads, different kinds of non-spherical sands, and grain-size-equivalent mixtures of these. Their careful analysis reveals a new grain-shape-dependent flow rule that resolves the above contradictions in the current literature and provides quantitative evidence for the statement that the deviations observed by Börzsönyi and Ecke can be attributed to the flows not having reached the steady state.[1] Pouliquen O. Scaling laws in granular flows down rough inclined planes[J]. Physics of fluids, 1999, 11(3): 542-548.[2] Kamrin K, Henann D L. Nonlocal modeling of granular flows down inclines[J]. Soft matter, 2015, 11(1): 179-185.[3] Börzsönyi T, Ecke R E. Flow rule of dense granular flows down a rough incline[J]. Physical Review E, 2007, 76(3): 031301.[4] Jenkins J T. Dense shearing flows of inelastic disks[J]. Physics of Fluids, 2006, 18(10).
Analysing the relation between changepoint year, elevation, and land cover over lower Columbia River basin in North America
Authors: Hamid Injila , Jothiprakash Vinayakam
Published: March 2024

Three homogeneity tests were carried out on the lower Columbia River basin namely, Standard normal homogeneity test, Pettit test and Buishand test for daily gridded rainfall data having spatial resolution of 0.5o spanning a period of 43 years from 1980 to 2022. These tests were employed to estimate the breakpoint year for each grid and plotted on a map for spatial visualization. It was observed that a close relation follows between the elevation of a place, its changepoint year and the land use land cover of that area. The elevation of an area affects the direction of propagation of moisture laden winds that are developed over the Southwestern part of US from Pacific Ocean and gulf of California. And eventually governing where and how much precipitation they will bring. Additionally, the land cover of an area governs the amount of evapotranspiration and hence the pressure difference between the moisture laden winds and the atmosphere over that land cover. When the daily precipitation records of 4 decades were analysed for homogeneity and changepoint year observed spatially, it was noted that a particular elevation and land cover showed similar breakpoint and a trend is being followed. This study provides a novel way of understanding the behaviour of changing precipitation patterns taking into account the long-term variability of 4 decades.Keywords: Homogeneity test, Change point analysis, Land use land cover, Lower Columbia River basin
The WInd VElocity Radar Nephoscope (WIVERN): a candidate mission for the ESA Earth Explorer
Authors: Battaglia Alessandro , Illingworth Anthony , Tridon Frederic , Kollias Pavlos , Maahn Maximilian , Hohenegger Cathy , Scarsi Filippo Emilio
Published: March 2024

The WIVERN (WInd VElocity Radar Nephoscope, www.wivern.polito.it) concept (Illingworth et al., 2018), is one of the two remaining candidate missions of the ESA Earth Explorer program. The mission is now entering Phase A, which is expected to end in July 2025 with, at the ESA User Consultation Meeting, the final selection of the mission that will be launched in 2032.WIVERN promises to complement the Aeolus Doppler wind lidar that measures predominantly clear air winds by globally observing, for the first time, the vertical profiles of winds in cloudy areas. The mission will also strengthen the cloud and precipitation observation capability of the Global Observing System by providing unprecedented revisit time of cloud and precipitation vertical profiles. The mission hinges upon a single instrument, i.e., a dual-polarization Doppler W-band scanning cloud radar with a circular aperture non-deployable main reflector larger than 3 m. The WIVERN antenna conically scans a large swath (of about 800 km) around nadir at an off-nadir angle of about 38o at 12  revolutions per minute. This viewing geometry allows daily revisits poleward of 50°, 20-km horizontal resolution, and approximately 1-km vertical resolution (Battaglia et al., 2022). A key element to achieve Doppler accuracy and large Nyquist folding velocity is the use of closely spaced pulse pairs with polarization diversity (one pulse is H polarised, the other V polarised). In this paper we will discuss the status of the mission including the updated scientific objectives and outline some of the technical challenges of the measuring technique. We will also present examples of Level 2 products with particular focus on the cloud and precipitation products highlighting the benefit of the improved sampling and of the reduced clutter particularly over ocean surfaces compared to nadir-looking radars.Illingworth, A. J., and Coauthors, 2018: WIVERN: A New Satellite Concept to Provide Global In-Cloud Winds, Precipitation, and Cloud Properties. Bull. Amer. Meteor. Soc., 99, 1669–1687, https://doi.org/10.1175/BAMS-D-16-0047.1. 
Battaglia, A., Martire, P., Caubet, E., Phalippou, L., Stesina, F., Kollias, P., and Illingworth, A.: Observation error analysis for the WInd VElocity Radar Nephoscope W-band Doppler conically scanning spaceborne radar via end-to-end simulations, Atmos. Meas. Tech., 15, 3011–3030, https://doi.org/10.5194/amt-15-3011-2022, 2022.
 
Integrating functional strategies to optimize temporal forest carbon sink potential
Authors: Liu Daijun
Published: March 2024

Increasing water stress on forests is emerging as a global phenomenon, resulting in the episodes of tree mortality, canopy die-offs and declines in ecosystem resilience, threatening the progress of global carbon neutrality. The role of tree functional strategies is pivotal in regulating forest ability to cope with water stress. To date, the species-level water stress strategies including closing leaf stomatal early, investing in stronger water transport structures, dropping leaves, storing water and developing deeper roots are well documented. However, how strategies found at the tree or species level scale up to characterise forest communities and their variation across regions is not yet well-documented. By combining eight water stress-related functional traits with forest inventory data from the USA and Europe (219,518 plots), we investigated the community-level trait coordination and the biogeographic patterns of water stress strategies for woody plants, and analysed the relationships between the strategies and climate factors. We found that the range of water stress strategies which dominated at community-level were consistent with those available at species-level. Traits associated with acquisitive-conservative strategies formed one dimension of variation, while leaf turgor loss point, associated with stomatal water strategy, loaded along a second. Surprisingly, spatial patterns of local water stress strategies were better explained by temperature than by aridity, suggesting a greater selective pressure on water demand over supply. These findings provide a basis on which to build predictions of forest response under water stress which are grounded in the dominant functional strategy, with particular potential to improve understanding of forest carbon sink potential in a changing climate.
Where could surface water be used for Managed Aquifer Recharge (MAR) in the Besòs catchment, considering quantity and quality aspects? 
Authors: Scrinzi Luciana , Pérez Sandra , Pujades Estanislao
Published: March 2024

In many parts of the world, including the Mediterranean region, climate projections indicate less average runoff available and more frequent extreme rainfall events. Several sub-catchments in the river basin district of “Cuencas Internas de Catalunya” already need to address an irregular availability of surface water and a high vulnerability to floods in a changing climate, as well as water quality issues in streams and aquifers. In this context, aquifers can play a key role as natural reservoirs to buffer the effects of climate change, although challenges exist to keep a balance between groundwater recharge (inflows) and discharge (outflows) while preserving water quality. With the Besòs catchment as a study area, monitoring data from 2007 to 2023 was gathered from the database of the Catalan Water Agency. Spatial distribution of surface water and groundwater hydrochemistry (CE, Cl, NO3-, PO43-, TOC, pH, T) were analyzed and contrasted for different river stretches, as well as time series of river flow and groundwater levels in alluvial aquifers. Potential interactions between rivers and underlying aquifers and differences in water quality were inferred through descriptive statistics and non-parametric tests for selected areas. Sites where Managed Aquifer Recharge (MAR) could be potentially implemented were identified, considering quantity and quality aspects at catchment scale as well as physical aquifer properties. These preliminary results will guide the development of numerical models where different schemes will be tested of MAR methods (e.g.: streambed channel modifications, bank filtration, water spreading, wells recharge) and recharge sources (e.g.: rivers and streams runoff, reclaimed water) for climate adaptation. 
Fault reactivation in clay-rich rocks – effects of water-clay interactions
Authors: Rast Markus , Madonna Claudio , Selvadurai Paul A. , Salazar Vásquez Antonio , Wenning Quinn , Ruh Jonas B.
Published: March 2024

Clay-rich rocks play an important role in critical practical applications, particularly as natural barriers in nuclear waste repositories and subsurface caprocks for CO2 storage. The interaction between electrostatically charged clay minerals and polar fluids (e.g., water) can lead to swelling or, under confined conditions, build-up of swelling stress. Fault closure by swelling in clay-rich rocks has been the focus of many studies. However, it remains unclear how water-clay interactions affect the stability of pre-existing faults, considering that in addition to changes in frictional properties, the stress state may also change due to the build-up of swelling stress.This study addressed this gap by conducting triaxial friction experiments on oblique saw-cut cylindrical samples. The upper half of the sample consisted of a clay-rich rock (Opalinus claystone) and the lower half of a permeable sandstone (Berea sandstone). The first set of experiments determined the friction slip envelope of the sandstone-claystone interface without fluid injection, at confining pressures ranging from 4 to 25 MPa, and a constant axial loading rate of 0.1 mm/min. These experiments showed a frictional strength well below Byerlee’s law, indicating that the Opalinus claystone dictates the strength of the two-material interface.Friction experiments with fluid injection were then performed at confining pressures of 10 and 25 MPa with a constant piston position (no axial loading) and an initial differential stress of about 70% of the expected yield stress. The aim was to compare the fluid pressures required to initiate slip in scenarios with and without fluid-clay interactions. For this, the experiments involved stepwise increases in fluid pressure through the injection of either deionized water (a polar fluid) or decan (a non-polar fluid). In one of the decane and one of the water injection experiments, fibre-optic strain sensors were attached to the sample surface. This allowed us to differentiate between poroelastic deformation within the matrix, deformation due to water-clay interaction, and elastic relaxation due to slip along the saw cut.The friction slip envelope based on decane injection experiments is within the uncertainty of the friction slip envelope based on the experiments with no fluid injection. In contrast, the water injection experiments indicate a weakening of the frictional interface. We interpret this weakening to be due to the transition of the claystone from a solid rock to a mud close to the saw-cut surface. This weakening was evident even at ambient fluid pressure, although the apparent stress state was below the yielding stress, indicating the need to consider swelling stress in initial water injection scenarios. In summary, our data suggest that water-clay interactions may reactivate pre-existing faults due to (1) the change of the frictional properties and (2) the build-up of swelling stress.
PPM+W, an improved version of the Piecewise Parabolic Method advection scheme: Description, evaluation and implementation in the CHIMERE model.
Authors: Mailler Sylvain , Pennel Romain , Menut Laurent , Cholakian Arineh
Published: March 2024

We have developed a new advection scheme for Eulerian models by combining the Piecewise Parabolic Method “PPM” (Colella, 1984) and the Walcek scheme (Walcek, 2000). The concept is to keep the excellent accuracy of the PPM scheme in the areas of smooth gradient, and to use the flux modifications of Walcek to improve over the PPM scheme in the vicinity of extrema. This combination forms a new advection scheme that we call PPM+W (“Piecewise Parabolic Method + Walcek”). We have studied the properties of this new scheme in the idealized framework of ToyCTM v1.0.1, an academic model including advection and stiff chemistry mimicking tropospheric photochemistry, including inert species and reactive species such as nitrogen oxide, ozones and radicals. This study shows that PPM+W reduces advection error by 10-30% compared to both the Walcek scheme and the PPM scheme. The efficiency of PPM+W is also good: the computation time for PPM+W is not higher than in the classical PPM scheme. Following these results, PPM+W has been implemented in the CHIMERE chemistry-transport model (CHIMERE v2023r1), and could also be useful for other models including atmospheric and oceanic models.Apart from the design of this new advection scheme, we present a novel method to evaluate advection schemes in contexts where mixing is weak / negligible, and show that this novel method gives results consistent with more classical methods, without requiring the knowledge of the exact solution.References:  Colella, P. and Woodward, P. R.: The piecewise parabolic method (PPM) for gas-dynamical simulations, J. Comput. Phys., 54, 174-201, https://doi.org/10.1016/0021-9991(84)90143-8, 1984  Mailler, S., Pennel, R., Menut, L., and Cholakian, A.: An improved  version of the piecewise parabolic method advection scheme: description  and performance assessment in a bidimensional test case with stiff  chemistry in toyCTM v1.0.1, Geosci. Model Dev., 16, 7509–7526,  https://doi.org/10.5194/gmd-16-7509-2023, 2023Walcek, C., Minor flux adjustment near mixing ratio extremes for simplified yet highly accurate monotonic calculation of tracer advection, J. Geophys. Res., 105, 9335–9348, https://doi.org/10.1029/1999JD901142, 2
Debris flow catchments and landscape evolution in the northern Colombian Andes
Authors: Aristizábal Giraldo Edier Vicente , Korup Oliver
Published: March 2024

Fans are cone-shaped depositional landforms composed of a mixture of sediments, mainly derived from debris flow processes at the catchment scale. In mountainous terrains located in humid climates, debris flows are fundamental agents of landscape evolution and a highly destructive natural hazard. In the northern Colombian Andes, fans have been traditionally occupied by human settlements, which has also produced a long history of disasters in many settlements located on fans. For example, a debris flow on November 13, 1985, devastated the city of Armero, killing approximately 22,000 people and causing economic losses totaling over $US 339 million. In 2017, the city of Mocoa was affected by a debris flow where 333 people died, 130 houses were destroyed, and 1461 were partially affected.Debris-flow risk is likely to increase as a consequence of the increasing magnitude and frequency of extreme weather and rapid population growth over the past few decades. Hence, identifying fan spatial distribution and debris flow occurrences is important for land use planning. In this study, we implemented geomorphometric analyses in the northern Colombian Andes to understand debris flow occurrence in terms of landscape evolution. Using digital elevation models, fan inventory, morphometric parameters, and geomorphic indices associated with the drainage network at the catchment scale, the close interconnection between debris-flow hazards and landscape evolution is explained.The results show a clear spatial pattern of fans location and debris-flow-prone basins with knickpoint upstream migration and transient-state catchments, those characterized by high values of Ksn, hypsometric index and constraint values of 𝛘. Those findings suggest that landscape evolution indexes could improve debris flow susceptibility assessment at regional scale.
Quieting of hydraulic tremor: sudden changes in frictional conditions in subglacial channels
Authors: Chmiel Małgorzata , Caldera Nicoletta , Walter Fabian , Olivier Gerrit , Farinotti Daniel , Guadagnini Alberto , Gräff Dominik , Köpfli Manuela , Gimbert Florent
Published: March 2024

The state and evolution of subglacial channels strongly impact glacier motion and as a result the mass balance of flowing ice bodies. Yet, the subglacial environment is difficult to access and thus often poorly constrained over significant temporal and spatial scales. This limits our understanding of complex subglacial hydraulic processes and consequently ice dynamics.Seismology can help overcome these observational constraints, providing new insights into fundamental processes in the cryosphere, such as frictional sliding and subglacial water flow. However, different seismogenic processes of the cryosphere often overlap in both time and space. Differentiating between them and interpreting associated seismic signals require appropriate methodological and instrumental approaches.Here, we investigate subglacial channel dynamics at the Rhone glacier (Switzerland) over one month in the summer of 2020, focusing on periods coinciding with glacier sliding episodes. To this end, we leverage the sensitivity of near-bed borehole geophones combined with seismic interferometry and beamforming techniques.We show that the hydraulic tremor, generated by turbulent water flow and resulting pressure variations acting against the subglacial channel bed and walls, acts as a dominant, stable, and coherent noise source. Beamforming analysis reveals the directional stability of the hydraulic tremor and points toward the junction of two subglacial hydraulic channels from which stick-slip asperities originate. The analysis also reveals instances of sudden hydraulic tremor quieting, in agreement with previous observations before and after seismogenic sliding episodes. We explain this quieting as sudden changes in frictional conditions within the subglacial channel corresponding to a rapid transition between a fully and partially filled channel. We discuss channel properties (geometry and bed conditions) that are needed to satisfy the physical conditions for the frictional quieting mechanism. Our analysis offers new insights into the complex mechanical interactions between ice, water, and bed properties and the hydraulic control of glacier sliding.
Reliable Ozone Measurements in Volcanic Plumes: A Way to Resolve the Volcanic Ozone Enigma
Authors: Rüth Maja , Karbach Niklas , Bobrowski Nicole , Platt Ulrich , Geil Bastien , Hoffmann Thorsten , Bräutigam Ellen , Kuhn Jonas
Published: March 2024

In addition to CO2 and sulphur dioxide (SO2), volcanic plumes also contain reactive halogen species. Bromine monoxide (BrO) can reliably be quantified by remote sensing measurements and is known to catalyse ozone (O3) destruction. Therefore, local O3 depletion is commonly assumed inside volcanic plumes.Contrary to popular belief, a calculation comparing atmospheric turbulent mixing with the rate of O3 destruction inside the (young) plume suggests no significant halogen catalysed O3 loss (1% or less) in the plume.So far, however, O3 and its concentration distribution in volcanic plumes have only been insufficiently determined since commonly used short-path ultraviolet (UV) absorption O3 monitors show a severe, positive interference with SO2, an abundant volcanic gas.This interference problem can be overcome by using a chemiluminescence (CL) O3 monitor, a standard technique for O3 measurements in the 1970s (and still the standard instrument for air pollution monitoring), which shows no interference with trace gases in volcanic plumes and therefore allows reliable O3 measurements in volcanic plumes.However, field measurements with existing CL O3 monitors are challenging, since they are usually heavy and bulky. We therefore designed an improved and lightweight version of the CL O3 instrument (1kg, shoebox size), which can be easily carried or mounted onto a drone, thus opening up completely new measurement possibilities.After test measurements in Heidelberg, including ground-based as well as drone-based measurements, during which we determined vertical O3 profiles, we performed drone-based O3 measurements in the plume of Etna volcano. The latter data show an anti-correlation between O3 and simultaneously determined SO2, suggesting an O3 depletion of up to ~60% in the plume of Etna. This raises the question which – probably unknown - process leads to this observed O3 depletion.
Transport mechanisms of Asian dust aerosol to the Tibetan Plateau
Authors: Zhang Xinyi , Wang Tianhe
Published: March 2024

Dust aerosols originating from major deserts of the surrounding Tibetan Plateau (TP), i.e., the Taklamakan Desert on the northern side, the Thar Desert on the southern side, and the Karakum Desert on the western side, can frequently assault the TP and greatly influence the regional climate over the TP. Airborne dust over the Tibetan Plateau (TP) influences the local climate by warming the atmosphere and altering cloud properties. Additionally, dust settling on ice and snow can accelerate their melting, impacting the hydrological cycle. A new Source-Tracing of Airborne Dust algorithm based on HYSPLIT was developed to evaluate the dominant remote sources and their contributions, based on the space-based lidar measurement and reanalysis dataset. Th Taklamakan, Karakum, and Thar deserts were found to be the most significant contributors. Furthermore, the transport mechanisms of Asian dust aerosols from the dominant remote sources were explored by combining the synoptic analysis and circulation classifications. These new findings pave the way for further revealing the contribution of dust aerosol from remote source to the melting of ice and snow on the TP and local climate change.
Towards a realistic modelling of gravimetric errors in future missions equipped with quantum sensors
Authors: de Teixeira da Encarnacao Joao , Siemes Christian , Daras Ilias , Strangfeld Aaron , Zingerle Philipp , Pail Roland
Published: March 2024

Cold Atom Interferometry (CAI) stands poised as a groundbreaking technique in satellite gravimetry, offering unparalleled precision and unbiased measurements. Despite the numerous studies on CAI's conceptual measurement techniques, attitude reconstruction accuracy poses a critical challenge. This submission seeks to bridge this gap by conducting an analysis of state-of-the-art attitude sensors and their suitability for upcoming quantum low-low satellite-to-satellite and gravity gradiometry missions utilizing CAI instruments.Acknowledging the immense promise of Cold Atom Interferometry, we emphasise the need to put this conceptual potential in the context of the accuracy of attitude reconstruction, a factor that significantly influences the feasibility of Quantum Space Gravimetric (QSG) missions. We examine the specifications, strengths, and limitations of attitude, acceleration, position and inter-satellite distance sensors to combine them realistically in scenarios specific to quantum low-low satellite-to-satellite and gravity gradiometry missions relying on CAI instruments. We also analyse the classic counterparts, offering valuable insights into the conceptual mission configurations that benefit the most from CAI-based observations. Our findings contribute not only to the advancement of the use of CAI technology in future graviemtric missions but also to the broader understanding of the intricate interplay between cutting-edge measurement techniques and the supporting instrumentation required for their successful implementation.This work is supported by the European Space Agency, under the project Quantum Space Gravimetry for monitoring Earth’s Mass Transport Processes (QSG4EMT), which has the general objectives to analyse future QSG mission architectures with ultimate goal to optimally exploit the performance of quantum sensors for retrieving temporal variations of Earth’s gravity field, evaluate the impact of mission configurations on the quality of the retrieved gravity field models and support the evolution of user requirements for future QSG missions.
Modeling variably saturated water flow within planned covers of a hypothetical potash tailings pile
Authors: Silva Monsalves Felipe Edgardo , Graf Thomas
Published: March 2024

Potash mining to obtain potassium generates large quantities of solid waste composed mainly of sodium chloride, accompanied in lesser quantities by magnesium sulfate and magnesium chloride, as well as insoluble clay minerals. The solid waste is disposed off on the ground surface to form tailings piles. In central Germany, there are dozens of potash tailings piles, some of which are more than two hundred meters high and form a unique landscape due to their appearance and lack of vegetation. Potash tailings are therefore exposed to climatic conditions such as rainfall, which may potentially dissolve salt, thus affecting the surrounding ecosystem including surface water bodies and groundwater. The environmental impact can likely be mitigated by applying soil covers over the potash tailings to limit and, in the best case, prevent the contact of the percolating water with the saline core of a pile. The efficiency of the soil covers is increased by applying a perennial vegetation layer to reduce the amount of water infiltration by interception, evaporation and plant transpiration. Therefore, the design of a cover system is based on the hydrological processes of the site, which include precipitation, surface runoff, evapotranspiration, in- and exfiltration and the water storage capacity of the soil. In addition, the type of soil cover and thus its hydraulic characteristics, the number of layers, the thickness of each layer, as well as the angle of slope of the layers can significantly influence the long-term efficiency of the cover. In conclusion, understanding the synergy between the soil cover and the potash tailing is essential to determine the effects caused on the surrounding environment, in particular on groundwater. The objective of this research work focuses on the numerical simulation of variably saturated water fluxes, in particular the creation of a water balance between surface runoff, in- and exfiltration and evaporation loss to the atmosphere in the soil cover. For this purpose, different configurations of vegetation covers are investigated and the capillary barrier effects are analyzed for each of them. The water flow through the potash tailing produced by the remaining infiltration through the vegetation cover is modeled for a hypothetical geometrical setting of a representative tailings pile.
DDE-Outcrop3D: A new pathway to the Deep-time Earth
Authors: Wang Xia , Zhong Hanting , Chen Jianhua , Lin Zongqi , Wang Bingqian , Hou Mingcai , Li Yalin , Wang Chengshan
Published: March 2024

Outcrops are the basics of geosciences. Investigation of geological outcrops is the bedrock of geological research, but the data acquisition based on traditional fieldwork is often limited by the size and accessibility of the outcrops. Especially in a hundreds-meter scale area, geological studies often rely on single-profile analysis, which makes it challenging to reveal the overall characteristics of systems with spatial heterogeneity (e.g., carbonate deposition, reef complex). For geological education, field excursions are necessary for the students, but the accessibility of the outcrops is seriously impacting the global equality of geological education because of regional conflicts or poverty. Geological heritage outcrops, important outcrops such as GSSP (Global Stratotype Section and Point), or outcrops with both scientific and commercial value need to be documented to prevent future destruction; besides the traditional solutions such as photography or videos, 3D digital outcrops can save more diversified geological information.Utilizing UAVs allows for a cost-effective and highly efficient approach to investigating outcrops. Through close-range photogrammetry employing UAV-captured images, the creation of precise three-dimensional models for outcrops has become feasible, reaching an impressive level of accuracy at the centimeter scale. Under the Deep-time Digital Earth (DDE) framework, the DDE-Outcrop3D platform (outcrop3D.deep-time.org) is an open-access Web platform for real-scene 3D digital outcrops. It is based on the Cesium open-source 3D earth engine, providing functions for multiple data uploading, sharing, information editing, and community outreach. DDE-Outcrop3D platform has 124 digital outcrop models from Asia, Europe, and Africa, all accessible to the public. The latest versions of DDE-Outcrop 3D can provide a new pathway to scientific research and education, and aim to foster broader engagement among researchers, educators, and enthusiasts, providing a valuable resource for immersive exploration and enhanced understanding of geological outcrops.Here, we present the main features of the DDE-Outcrop3D platform and its application scenarios on geological research and education, scientific communication, and preservation of geological heritages. Acknowledgement: This work is funded by “Deep-time Digital Earth”, an IUGS-recognized Big Science Program.
Leveraging High-Performance Computing for Enhanced Lava Flow Forecasting Workflow
Authors: Costa Antonio , Cordrie Louise , Macedonio Giovanni , Ganci Gaetana , Cappello Annalisa , Zuccarello Francesco
Published: March 2024

The integration of lava flow forecasting models with satellite remote sensing techniques marks a significant advancement in quantitative hazard assessment for effusive volcanic eruptions. Within the framework of the DT-Geo project, we are developing a lava flow workflow that harnesses High-Performance Computing (HPC) capabilities, aiming to improve hazard assessment through ensemble-based and data assimilation methods.At the core of the workflow is the VLAVA code, which simulates the lava flow propagation, with temperature-dependent viscosity over a complex topography, erupting from one or more vents. The simulation runs for a given time period (order of one or more days), after which the simulated deposit is compared to the observed  lava flow field and, eventually, the observations are assimilated into the model for a further simulation. The measured data include changes of the eruption source parameters and/or the extension and temperature of the lava flow field. These are derived from direct observations on the field or by remote sensing from airborne, drones or satellites (e.g.: Pléiades, EOS-ASTER, SEVIRI, MODIS, VIIRS, Landsat, Sentinel, etc.). Data assimilation is conducted using PDAF, a dedicated software offering various approaches, including ensemble-based Kalman filters, nonlinear filters, and variational methods.The model output provides the potentially impacted area by lava flows, including thickness and temperature distribution, for both a single scenario (utilized for estimating the impact of a lava flow) and an ensemble of weighted scenarios (for generating probabilistic hazard maps). We present the overarching concept of the workflow and share preliminary results obtained for historical eruptions of Mount Etna.
Deciphering the impact of future individual Antarctic freshwater sources on the Southern Ocean properties and ice shelf basal melting
Authors: Kittel Christoph , Jourdain Nicolas , Mathiot Pierre , Coulon Violaine , Burgard Clara , Caillet Justine , Maure Damien , Lambin Clara
Published: March 2024

The Antarctic ice sheet is losing mass. This mass loss is primarily due to ice shelf basal melting and the subsequent acceleration of glaciers. The substantial freshwater fluxes resulting from ice shelf and iceberg melting affect the Southern Ocean and beyond. As emphasized by some studies, they slow down the decline of Antarctic sea ice and hinder mixing between surface water and Circumpolar Deep Waters, further intensifying ice shelf basal melting. In this context, most studies so far have neglected the impact of surface meltwater runoff , but recent CMIP6 projections using the SSP5-8.5 scenario challenge this view, suggesting runoff values in 2100 similar to current basal melt rates. This prompts a reassessment of surface meltwater future impact on the ocean.  We use the ocean and sea-ice model NEMO-SI3 resolving the sub-shelf cavities of Antarctica and including an interactive iceberg module. We perform thorough sensitivity experiments to disentangle the effect of changes in the atmospheric forcing, increased ice shelf basal melting, surface freshwater runoff and iceberg calving flux by 2100 in a high-end scenario. Contrary to expectations, the atmosphere alone does not substantially warm ice shelf cavities compared to present temperatures. However, the introduction of additional freshwater sources amplifies warming, leading to escalated melt rates and establishing a positive feedback. The magnitude of this effect correlates with the quantity of released freshwater, with the most substantial impact originating from ice shelf basal melting. Moreover, larger surface freshwater runoff and iceberg calving flux contribute to further cavity warming, resulting in a noteworthy 10% increase in ice shelf basal melt rates. We also describe a potential tipping point for cold ice shelves, such as Filchner-Ronne, before the year 2100.
Probing the link between interplanetary magnetic field directional changes and bow shock geometry using simultaneous Cluster-MMS observations
Authors: Munteanu Costel , Teodorescu Eliza , Echim Marius , Voitcu Gabriel , Teodorescu Maximilian , Negrea Cătălin , Dumitru Daniel
Published: March 2024

We compiled a catalogue of 117 simultaneous Cluster-MMS magnetosheath crossings in 2017-2021 (http://www.spacescience.ro/projects/twister). The catalogue includes estimates of bow shock orientation for each event. Assuming that the bow shock normal direction does not change significantly during the magnetosheath crossing duration, we estimate the time evolution of θBn as the angle between the 1-minute time-resolution OMNI interplanetary magnetic field (IMF) and the estimated bow shock normal, and we calculate percentages of quasi-perpendicular (45°< θBn
Deglacial AMOC sensitivity in freshwater hosing experiments using CESM
Authors: Latinovic Dragan , Merkel Ute , Prange Matthias
Published: March 2024

The last deglaciation is characterized by a sequence of abrupt climate events, with melting ice sheets as its most distinctive feature. By meltwater release, ice sheets affect the oceanic circulation and modulate the Atlantic Meridional Overturning Circulation (AMOC). Understanding the stability of the AMOC under deglacial boundary conditions is therefore of vital importance for a better understanding of the climate trajectory from the Last Glacial Maximum (LGM) to the Holocene. To this end, we explore the impact of different glacial/deglacial boundary conditions (greenhouse gas concentrations (GHG), orbital parameters, ice-sheet topography) on the stability of the AMOC in freshwater hosing experiments using the Earth system model CESM1.2. This study is part of coordinated activities within the German climate modeling initiative (PalMod). For this purpose, three different configurations with various combinations of boundary conditions are used: (i) Full 15.2 ka boundary conditions, (ii) 15.2 ka boundary conditions except for LGM GHG, and (iii) LGM boundary conditions with 15.2 ka ice-sheet topography. After initial spin-up model integrations (3000-4000 years), freshwater hosing (0.1 Sv and 0.2 Sv; 400-700 years) is performed to each experiment, in which the AMOC is perturbed in the ice-rafted debris belt in the Northern Atlantic Ocean (40°N–55°N, 45°W–20°W). We find that the AMOC is most stable with respect to hosing under full 15.2 ka boundary conditions. Under reduced (LGM) GHG forcing, the AMOC becomes more unstable and collapses with only 0.1 Sv of freshwater hosing. Under certain conditions (15.2 ka boundary conditions with 0.1 Sv hosing) the AMOC exhibits bistability. Abrupt recovery along with an overshoot of the AMOC after removal of the hosing resembles Bølling/Allerød (B/A) warming by its intensity and duration. Finally, spontaneous (unhosed) millennial-scale AMOC oscillations are found under LGM boundary conditions with 15.2 ka ice-sheet topography. In sum, our set of experiments indicates that the deglacial AMOC evolution was the result of a non-linear complex interplay between different forcing factors rather than a simple (linear) response to meltwater forcing.
Isotopic composition in blood as a diagnostic tool of health in large Arctic wildlife
Authors: Hansson Sophia , van Beest Floris , Schmidt Niels Martin , Le Roux Gaël , Gourlan Alexandra , Team Atcaf
Published: March 2024

Although mainly used in archeology and human medicine, recent studies have shown that not only humans but also captive animals exhibit a shift in isotopic ratios of e.g. Cu and Zn in blood when suffering from a deterioration of health. For example, previous studies have shown that the ratio of 65Cu and 63Cu in blood from domestic canines was significantly lower in dogs diagnosed with cancer compared to healthy dogs, and similar results have also been shown for captive wild felids. Yet studies on blood chemistry from wild animals in general, and on Arctic wildlife specifically, are still scarce and the isotopic ratios within such samples, including potential shifts, are entirely unknown. Our aim was therefore to quantify, for the first time, the 65Cu/63Cu ratio in blood from wild and captive muskoxen (Ovibos moschatus) and to test the hypothesis that the isotopic ratio would decrease with a deterioration of health. To test this notion, we collected blood from muskoxen that were either captive (i.e. from zoo’s in Sweden and Denmark), wild (i.e. from long-term wildlife monitoring program in North-East Greenland), or culled (i.e. from population management programs in Norway). These samples were then analyzed for total-chemistry using iCapTQ/HR-ICP-MS analysis and for Cu-isotopic composition using MC-ICP-MS analysis. In addition, ecological traits (i.e. age, sex, body weight, body condition) were registered and blood serum analysis (i.e. SAA, cortisol levels) were performed to provide information on the health status of each animal. Our preliminary results show that the measured 65Cu/63Cu signatures range from -1.55 to 0.22, and appear to cluster with sample group (wild vs captive) in which the captive animals consistently showed higher 65Cu/63Cu signatures vs the wild or culled animals. We also found support for our hypothesis that there is a link between the Cu-isotopic signature and the overall health of the animal as the lowest detected Cu-isotopic signatures were found in animals with low body condition scores and with relatively low values of Fe, yet more data are needed to fully confirm this. Although preliminary, these results still indicate that Cu-isotopic ratios in animal blood can serve as a diagnostic tool to determine the health of large wildlife, which in turn could be used to facilitate and improve wildlife management programs in remote locations such as the Arctic.
Simulating glacial cycles from the Pleistocene to the end of the Anthropocene
Authors: Alvarez-Solas Jorge
Published: March 2024

The climate of the Pleistocene is characterized by alternating cold (glacial) and warm (interglacial) periods. This cyclicity is mainly caused by the so-called Milankovitch cycles as a result of periodic changes in Earth’s orbital parameters. Many models have already successfully captured the non-linearities of the climate-cryosphere system responsible for the 100 kyrs cycles and the Mid-Pleistocene transition. However, these models widely differ in the number of explicit physical processes included and in the degree of complexity to solve them (from purely conceptual to Earth-system models). In this talk I will present a simple a-dimensional model that sequentially includes ice-sheet dynamics, ice aging and climate-cryosphere feedbacks. This model is able to capture the timing and shape of glacial cycles of the last 2 million years and can also be used to predict future glacial inceptions and thus the duration of the Anthropocene. Following different assumptions of human greenhouse gas emissions, I will show the expected timing of future glacial inceptions as well as the periodicities of the late Anthropocene glacial cycles.
Urban roughness sublayer characteristics: sensitivity to planetary boundary layer schemes and multi-layer urban models
Authors: Zhang Wanliang , Fung Jimmy Chi Hung , Wong Mau Fung Michael
Published: March 2024

The Pearl River Delta (PRD) region in China is characterized by a large fraction of urbanized areas of which the growth rate is unprecedented. Modelling a realistic meteorological field for such a region is challenging mainly due to the uncertainties in the meso-scale numerical model, and the paucity of high-resolution profiler-type observations. In this study, we aim to improve the understanding of the urban effects on the modelled meteorological field in the PRD region by applying different fine-tuned planetary boundary layer (PBL) schemes coupled with two multi-layer urban models and leveraging the high spatial-temporal wind LiDAR observations. Particularly, the momentum in the urban roughness sublayer (RSL, about three times the building height) will be thoroughly investigated using long-lasting profiler-type observations.The Weather Research and Forecast (WRF) model offers a variety of PBL schemes which may feature a non-local transport algorithm under unstable atmospheric conditions. Most PBL schemes utilize the surface layer fluxes calculated based on the Monin-Obukhov similarity theory, acting on the first model layer only. Although this bulk parameterization of surface layer fluxes is appropriate for urban areas occupied predominantly by low-rise buildings, it is unable to reflect the momentum drag and thermal exchange processes when the average building height (H) within a model cell greatly exceeds the height of the lowest model. Multi-layer urban models, Building Effects Parameterization (BEP), and Building Energy Model (BEM) can be coupled with PBL schemes to provide a more realistic interaction between buildings and air within the RSL. Required input for initializing the multi-layer urban models include H and average street width, which can be simply prescribed (assumed) or derived from the local climate zones.Despite many efforts have been made to study the improvements by urban models on the surface meteorological variables, such as 10-m wind speed, 2-m temperature and moisture, little investigation of modelled results has been carried out focusing on the RSL and the entire boundary layer over a long-time series due to scarce observations. Recently, three wind LiDAR units were deployed in Hong Kong, providing us with a valuable opportunity to monitor wind profile evolution continuously at a 25-m and 1-hr resolution and to reveal the transport of surface layer fluxes to the overlying RSL.  In the result section, we first present the wind speed profiles to understand the benefits of a multi-layer urban model compared to the bulk parameterization, justified by the LiDAR observations. Secondly, as the non-local PBL scheme can transport the surface fluxes to non-adjacent cells, a comparison of the momentum flux profile will be presented between local and non-local PBL schemes under different stabilities.
The role of hydrological circulation in the initiation process of debris flows in the Campanian volcanic terrain
Authors: Pace Letizia , Domenico Capolongo , Giovanna Capparelli , Gabriele Clausi , Fabio Dioguardi , Roberto Sulpizio
Published: March 2024

Volcaniclastic debris flows are highly concentrated flows of rock debris, mud and water in which the sediment is of volcanic origin. These phenomena can be syneruptive, posteruptive, or unrelated to an eruption. To be generated, the coexistence of steep slopes, unconsolidated sediments and an adequate amount of water is necessary.The aim of this project is to investigate the role of water circulation in the initiation processes of debris flows to enhance our ability to anticipate potential new debris flows in the Campanian Volcanism area, focusing on the Sarno area. Sarno is a small municipality located in the Vesuvius Volcanism area (western side of the Campanian Apennines) that is sadly infamous for the major debris flow events that, on the 6th of May 1998, destroyed the town and killed around 150 people.The study area exhibits a convergence of geomorphological and lithostratigraphic settings that contribute to enhancing its exposure to hazards: i) the presence of a calcareous bedrock with very steep slopes (30-45°) mantled by ii) an alternation of colluvium and pyroclastic deposits, and iii) natural scarps and man-made cuts that further worsen the stability conditions.This research employs a multimethodological approach including i) geotechnical and rheological analyses of the sediments; ii) X-ray Diffraction for the mineralogical characterisation, particularly of the clay fraction; iii) large-scale experiments to investigate the role of water circulation in the sediments during simulated rainfall in the triggering of volcaniclastic debris flows; iv) in situ Time-Domain Reflectometry measurements at Pizzo D’Alvano for soil moisture vertical distribution and v) simultaneously acquisition-surveys by using a drone-mounted passive radiometer for spatial soil moisture distribution. Integrating these methods aims to achieve understanding of the water content distribution in the debris flow initiation process that could be potentially used in the rainfall-triggered landslide early-warning systems.