bluuebunny/crossref_metadata_2025 huggingface dataset:
Long-Term Effects of Silphium perfoliatum on Soil Pore Dynamics and Organic Carbon Accumulation
Authors: Lucas Maik , Rohlmann Lina , Deiglmayr Kathrin
Published: March 2024

Perennial bioenergy crops like Silphium perfoliatum (cup plant) are a promising alternative to currently used energy crops such as maize because of their positive feedbacks on various soil properties including carbon sequestration, edaphon activity and erosion control. This study investigates the long-term impact (over 10 years) of the cup plant on soil organic carbon and soil structural parameters in comparisons to a to a nearby ploughed reference site.We employed tension infiltrometers to measure water infiltration rates at two soil depths (5 and 45 cm). Following this, 100 cm³ aluminum soil cores were extracted for X-ray computed tomography at a resolution of 35 µm. The image analysis, enhanced by machine learning, classified structures including roots, particulate organic matter (POM), biopores, and two types of soil matrix: dense and loose, the latter indicating higher carbon content or more pores slightly below image resolution. The dataset was complimented by the determination of total carbon content and the root length distribution with RhizoVisionExplorer.The results indicate significant differences in pore structure, primarily in the topsoil, where the cup plant site showed a greater volume of biopores than the reference site. In contrast, the subsoil differences were less marked. Organic carbon content analysis demonstrated a notable increase in the upper soil layer (10-15 cm) at the cup plant site, contributing to a higher soil organic carbon stock than the reference site. However, this effect diminished with depth, becoming negligible at 50-55 cm. In the topsoil, extensive bioturbation/biomixing was observed, as indicated by the darker, more loosely structured soil matrix, which often had the shape of biopores. This bioturbation, which mixed particulate organic matter (POM) into the soil, significantly enhanced soil organic carbon, as evidenced by linear regression analysis.These findings underscore the substantial impact of the perennial cup plant in enhancing soil structure and carbon content, particularly in the topsoil.
Estimating the annual accumulation of the Khumbu Glacier, Nepal, using weather station data
Authors: Graves Benjamin
Published: March 2024

Estimates of glacier accumulation are a vital part of determining annual glacier mass balance. Here, the annual accumulation of the Khumbu Glacier, Nepal, is estimated using data from a dense network of high-altitude weather stations in the Khumbu Valley, extending to the summit of Mount Everest. Observations of precipitation phase are used to refine methods of phase modelling using logistic regression in conjunction with weather station and precipitation gauge data. Seasonal temperature lapse rates and spatio-temporal patterns of precipitation are inferred from weather station data, and observed precipitation is adjusted for snow undercatch based on modelled precipitation phase and wind speed. These methods are then combined and distributed over the glacier surface to produce an overall estimate of seasonal and annual accumulation rates of the Khumbu Glacier. 
Towards a theory for the formation of sea stacks
Authors: Fowler Andrew , Ng Felix , Kember Guy
Published: March 2024

Sea stacks are isolated cliff-bound columnar islands, which are formed as shore-line cliffs are eroded by ocean wave action. We have developed a theory which aims to explain how they can be formed, and in this talk we will provide a description of the mathematical model in its present form, some analytic insights into its behaviour, and some numerical computations of the solutions.The key idea in the model is that eroded cliffs provide shore-line debris which enhance erosive power during storms, thus providing a positive feedback which enables spatial instability of a uniformly receding cliff face. Important ingredients in the model are along-shore boulder transport, and a newly-introduced ‘cliff energy length’, both of which provide regularising effects on what would otherwise be an ill-posed (and thus physically meaningless) model.We provide analytical and numerical results which may provide insight into the formation of headlands and inlets, and we also discuss the potential application of the model to the formation of sea stacks.
A Stacking Ensemble Method for Comprehensive Flood Susceptibility Mapping in Yemen
Authors: Ghaleb Mustafa , Al-Areeq Ahmed , Al-Areeq Nabil , Saleh Radhwan , AbuDaqa Anas , kawara Atef
Published: March 2024

The necessity of flood risk mapping is critical for effective planning and disaster response, particularly in flood-prone regions like the Qaa'Jahran watersheds in Dhamar, Yemen. This research implements various machine learning methods, including Support Vector Machines (SVM), K-Nearest Neighbors (kNN), Random Forest (RF), Artificial Neural Networks (ANN), and Logistic Regression (LR), with the latter also functioning as the meta-model in our stacking ensemble approach for mapping flood susceptibility. The process began with creating a flood inventory map using SAR images and historical flood records. Our model integrates the individual strengths of each technique and employs a meta-model to synthesize their forecasts. This stacked ensemble approach demonstrated superior performance over each model alone, achieving a remarkable AUC score of 0.9848 compared to the individual scores of SVM, LR, kNN, ANN, and RF. It also surpassed two innovative models, ABRBF and TPOT, in accurately pinpointing all high-risk zones identified in historical flood data. This advancement in flood risk mapping for the Qaa'Jahran watersheds exemplifies the potential of our model in enhancing disaster management and prevention efforts. It offers a significant tool for identifying at-risk areas and guiding mitigation strategies to safeguard communities in Dhamar, Yemen, against the catastrophic impacts of flooding.
On the impact of thunder on cloud droplets and ice crystals
Authors: Kourtidis Konstantinos , Stathopoulos Stavros
Published: March 2024

In the lightning channel pressures can be of the order of 100 atm and hence in the produced thunder, sound pressure levels (SPL) can be very high. Additionally, the thunder frequency spectra have peaks for peal and claps at around 100 Hz and around 50 Hz for rumble sounds, with intracloud lightning having peaks at even fewer Hz. These low frequencies are ideal for acoustically induced orthokinetic agglomeration of droplets. Thunder occurs in cloud environments where not only large numbers of droplets are present, but additionally the shockwave front expands at supersonic velocities and hence could cause near the lightning channel modulations of droplet size distributions and increase ice crystals numbers through e.g. vibrational breakup. We present calculations for the two mechanisms above (orthokinetic agglomeration and vibrational breakup) for typical cloud droplet sizes and concentrations, including also clouds containing desert dust. In thunderstorm conditions, it is found that acoustic orthokinetic agglomeration of droplets can be very effective and can produce very rapidly changes in the mean cloud droplet diameter. Also, it is found that the critical flow velocities, over which breakup occurs, is easily exceeded near the lightning channel and will lead to droplet and ice crystal breakup. We note that all models of ice crystal generation in clouds substantially underestimate the observed ice crystal numbers, and the mechanism presented here may be responsible for the discrepancy. We also note that these processes need further study to assess how they could interfere with the lightning generation process itself, through both charge redistribution in the modified droplet size distribution spectra, as well as the increase in vertical and turbulent transport velocities of the smaller ice crystals resulting from breakup. 
Compound hot extremes at an urban site based on climatic and bioclimatic indices 
Authors: Founda Dimitra , Pierros Fragiskos , Katavoutas George
Published: March 2024

Over the past decades, extreme weather phenomena like hot extremes and heat waves (HWs) stand out as a major threat for humans and ecosystems. Compound extremes are understood as simultaneous, concurrent or sequential extreme events, taking place at a single or different locations. Compound extreme events may exacerbate the risk and increase associated adverse impacts, compared to individual events.In the study, we examined the occurrence of compound hot extremes at an urban site of the eastern Mediterranean over a century-long period, using the historical climatic records of the National Observatory of Athens (NOA, 1897-2023). Compound hot extremes are defined as concurrent daytime and nighttime hot extremes, namely cases when both, daily maximum (Tmax) and daily minimum (Tmin) air temperatures are above a predefined threshold value. The threshold values for Tmax and Tmin were set equal to 36.7 oC and 25.9 oC respectively, corresponding to the 90th percentile of the summer Tmax and Tmin distributions at NOA, over the reference period 1981-2010. Likewise, we examined compound heat waves, defined as sequences of at least 3 consecutive days when both Tmax and Tmin exceed the predefined thresholds. Analysis has shown that 60% of the total number of compound hot extremes and compound heat waves in Athens (NOA) was observed from 2000 onwards. Besides, 57% of the daytime HWs over the whole study period constitute also compound HWs, while this percentage increases to 72% after the 2000s, indicating an increase in nighttime HWs, very likely related to the urban heat island effect. In addition to the hot extremes based on air temperature, we have also estimated compound daytime and nighttime extremes related to human thermal comfort, using the bioclimatic index UTCI (Universal Thermal Climate Index), accounting also for relative humidity, solar radiation and wind speed conditions. Compound hot extremes based on UTCI were defined as the cases when the daily maximum UTCI value  was above the index threshold indicating ‘at least very strong heat stress’ (UTCI > 38), and simultaneously, the daily minimum UTCI value was above the index threshold indicating ‘at least moderate heat stress’ conditions (UTCI > 26). The analysis detected 45 compound hot extremes based on UTCI from 1960-2023, with 34 of them occurring after the 2000s, suggesting a dramatic increase in the frequency of cases with heat-related thermal discomfort throughout the whole day and night.  The higher frequency of compound hot events was observed during the extreme years 2007, 2021 and 2023. 
Hoop Stresses in Free Subduction on a Sphere
Authors: Ribe Neil , Chaillat Stephanie , Gerardi Gianluca , Chamolly Alexander , Li Zhonghai
Published: March 2024

Because Earth's tectonic plates are doubly curved shells, their mechanical behavior during subduction can differ significantly from that of flat plates. We use the boundary-element method to study free (gravity-driven) subduction in 3-D spherical geometry. The model comprises a shell with thickness h and viscosity η1 subducting in a viscous planet with radius R0. Our focus is on the magnitude of the longitudinal normal membrane stress (`hoop stress'), which has no analog in Cartesian geometry. Scaling analysis based on thin-shell theory shows that the resultant (integral across the shell) of the hoop stress obeys the scaling law Tφ ∼ (η1h W/R0) max(1, cotθ) where θ is the colatitude and W is the velocity of the shell normal to its midsurface that is associated with bending. We find that the state of stress in the slab is dominated by the hoop stress, which is 3-7 times larger than the downdip stress. Because the hoop stress is compressive, it can drive longitudinal buckling instabilities. We perform a linear stability analysis of a subducting spherical shell to determine a scaling law for the most unstable wavelength, which we compare with observed shapes of trenches in the Pacific ocean. 
Constraining Hydrological Sensitivity in Tropical Oceans
Authors: He Jie
Published: March 2024

Precipitation is an important aspect of the climate and is expected to change from increasing greenhouse gases. However, model projections of precipitation changes are stubbornly uncertain, particularly in tropical regions. It has been long recognized that much of the uncertainty in tropical precipitation changes is rooted in the uncertainty in sea surface temperature (SST) changes. But unfortunately, constraining SST changes at regional scales has been quite difficult. Here, we advocate that instead of fixating on regional SST changes, it is much more productive to focus on constraining precipitation sensitivity to SST changes (i.e., hydrological sensitivity). We show that local hydrological sensitivity varies widely among the state-of-the-art global climate models, but it can be effectively constrained by honing in on specific aspects of the observed precipitation-SST relationships. We find that despite the large inter-model disagreement, regional hydrological sensitivity in tropical oceans is accurately projected by the CMIP6 multi-model averages.
Attribution of tropical sea surface temperature change on extreme precipitation over the Yangtze River Valley in 202
Authors: Wang Qian , Zhai Panmao , Zhou Baiquan
Published: March 2024

Record-breaking extreme precipitation occurred over the Yangtze River Valley (YRV) in June-July 2020. The impact of climate change on this event is examined from the perspectives of key physical processes including synoptic-scale circulation pattern and tropical sea surface temperature (SST) forcing based on self‐organizing map approach and the regularized optimal fingerprinting method. The results indicate that the increase in extreme precipitation over the YRV has accounted for 69% of the increase in total precipitation since 1961. Both the amount and frequency of extreme rainfall during the Meiyu period in 2020 broke the historical record since 1961. The SST warming in tropical Indian Ocean (TIO) and tropical Atlantic Ocean (TAO) lead to the anomalous anticyclone in the Northwest Pacific, which further aggravate the occurrence of extreme precipitation in the YRV. Human influence is the primary cause for the observed SST rise in TIO and TAO since 1961, to which anthropogenic greenhouse gas emissions contribute the most. Quantitatively, the changes of TIO and TAO SST caused by anthropogenic forcing are 0.12℃/10a and 0.08℃/10a, respectively. Such SST warming drives the frequency change of synoptic-scale circulation patterns through air sea interaction. The higher occurrence likelihood of circulation patterns conducive to precipitation in all forcing experiment than that in natural forcing proves that the extreme precipitation in the YRV in 2020 is attributable to human-induced climate change.
Updates of a Global CO2 Emission Inventory (1960–2019) with Highly Resolved Source Information
Authors: Xu Ruibin
Published: March 2024

A CO2 emission inventory with highly-resolved spatial granular and source categories provides valuable information for scientific research on climate change. Here we present an updated CO2 emission inventory, the Global Emission Modeling System for CO2 (GEMS-CO2) covering the period from 1960 to 2019, based on a previous inventory (PKU-CO2) and incorporating highly-resolved spatial and sectoral information. This inventory was developed using a bottom-up approach and incorporates subnational activity data, emission factors, and combustion efficiency. It includes 225 countries/regions, seven sectors (energy, industry, transport, residential, commercial, agriculture, and industrial process), five fuel types (coal, oil, gas, waste, and non-renewable wood fuel) and 16 industrial processes, making up a total of 92 source categories. Notably, we account for carbon emissions from parts of wood fuel due to non-renewable wood harvesting. We further differentiate the residential and commercial sectors into 38 fuel sub-types and the transport sector into 20 sub-types, mainly focusing on road and navigation vehicles. Emissions are presented in annual and monthly resolutions (mainly covering monthly residential energy consumption), with a spatial resolution of 0.1º × 0.1º. Our inventory aligns with some global inventories but differs slightly from others. Results show that from 1960 to 2019, human activity contributed to a cumulative emission of 1352.0 (1265.3–1443.6 as inter-quartile range) Gt CO2 and annual emissions increase threefold from 9.1 Gt CO2 yr-1 in 1960 to 36.7 Gt CO2 yr-1 in 2019. This increment is mainly driven by bituminous and natural gas in energy sector, passenger gasoline, motor vehicle diesel, domestic aviation, pig iron and cement production, and bituminous and natural gas in industry sector. In residential sector, the combustion of natural gas and LPG are key increasing drivers while the coal use is decreased, indicating a shift from coal to oil and gas under the increasing energy needs. Our high-resolution map presents high emission densities in China, USA, India, Japan, and some Europe countries for year 2019. Developing Asian countries, especially China, India, and Malaysia, show highly-varied emission densities for a recent decade. Overall, our inventory provides detailed datasets, particularly in the residential, commercial, and transport sectors, for comprehensive research on climate change mitigation and adaptation.
Research informing policy to adapt to climate change: a case study from the Murray-Darling Basin, Australia
Authors: Post David
Published: March 2024

The Murray-Darling Basin in south-eastern Australia is one of the world’s largest rivers, draining an area of just over 1 million square kilometres. The basin drains about one-seventh of the Australian land mass and is the 16th longest river in the world. However, being located on the driest continent on Earth, its discharge is relatively small, averaging just 767 m3/s, far smaller than the discharge from any other similarly sized river worldwide.Despite the relative lack of water, the Murray-Darling Basin is one of the most significant agricultural areas in Australia. In 2008, the Murray-Darling Basin Authority was formed with a mandate to manage the basin in an integrated and sustainable manner. Water reform in the basin has been a world-first in terms of the scale of intervention, but it has led to numerous conflicts in terms of access to water. The ability to manage the basin adequately relies on appropriate research being carried out in order to determine how much water is currently available, where it is currently being used, and how water availability and use are likely to change into the future.Climate change projections for the Murray-Darling Basin indicate a future that is likely to be hotter, with more frequent and intense droughts, accompanied by a reduction in cool season rainfall, particularly in the south of the Basin. As this is where the majority of runoff is generated, this is likely to lead to reductions in water availability, with a median reduction of around 20%.The Murray-Darling Basin Plan was brought into force in 2012 and is due for review in 2026. CSIRO is carrying out hydroclimate research to assist policy makers to better understand the likely changes in water availability, and consequent adaptation options available to them. This presentation will summarise the likely climate change impacts on water availability and assess how best to deal with the uncertainties associated with these projections.
Future Intensification of Marine Heatwaves in Marine Protected Areas
Authors: Cho Eun Byeol , Kwon Eun Young , Timmermann Axel
Published: March 2024

Marine Protected Areas (MPAs) are designated areas aimed at preserving marine ecosystems. However, they encounter the persistent obstacle of increasing ocean temperature. The occurrence of extreme warming events, known as Marine Heatwaves (MHWs), poses a significant threat to the delicate balance of marine ecosystems within MPAs. To understand the future changes in marine heatwaves (MHWs) in these regions, it is crucial to utilize advanced climate modeling capable of accurately capturing regional bathymetric features in MPAs, like coastlines, continental shelves, or islands. In this study, we utilized the SSP585 greenhouse warming simulations conducted with the OpenIFS-FESOM2 coupled model (AWI-CM3, 31 km atmosphere resolution, 4-15 km ocean resolution) to explore future changes in MHWs in the epipelagic to the upper mesopelagic zones (0-500m depth) of the global MPAs. In the current climate, MHWs in the MPAs exhibit greater maximum intensity and higher frequency than the global averages. However, MHWs in MPAs have shorter durations, leading to a lower cumulative intensity. The average warming rate within the MPAs is similar to or slightly lower than the average warming rate of the global ocean. Nevertheless, the MPAs are expected to see a 20% greater increase in the cumulative intensities of MHWs compared to the global ocean, from the past to the future. The findings suggest that marine protected areas (MPAs) are more susceptible to extreme temperature events compared to open ocean zones. Our findings underscore the significance of addressing anthropogenic warming to safeguard MPAs, emphasizing the need for prompt measures to mitigate these impacts and protect these vital marine ecosystems. 
Modelling the effects of long-term tillage practices on soil organic carbon stocks in Pyhra
Authors: Toth Marton , Davies Jess , Quinton John , Stumpp Christine , Klik Andreas , Mehdi-Schulz Bano , Liebhard Gunther , Strauss Peter , Strohmeier Stefan
Published: March 2024

In contrast to conventional tillage, conservation practices can increase carbon storage in the topsoil. However, it remains unclear how soil organic carbon (SOC) changes under future climate, which would be essential striving towards sustainability. Process-based models are useful for exploring future environmental changes and understanding how systems may respond to multiple future drivers. Here, we applied the model N14CP, an integrated terrestrial C-N-P cycle model, to a nearly three-decadal long-term field experimental site in Lower Austria to simulate and determine the impacts of conventional tillage (CT), mulch tillage (MT), and no-till (NT) practices in combination with climate scenarios on SOC stocks in the topsoil (0-15 cm). Presumably, the experimental site was used as a grassland for centuries before being converted into conventionally tilled arable land in 1970; the MT and NT tillage plots were laid out in 1994. Since then, the study site was comprehensively sampled in 2002, 2013, and 2023. The research quantifies the long-term SOC stock changes from 1994 to 2100, considering the three tillage practices and RCP4.5 and RCP8.5 climate scenarios in the near (2021-2050) and far (2071-2100) future. The N14CP model performed well with the measured and simulated data validation. Based on our estimations, the NT is the only tillage practice that could increase SOC stocks between 1994 to 2100. However, considering +1.4 °C and +2.3 °C (RCP4.5) as well as +1.3 °C and +4.0 °C (RCP8.5) potential changes in the short-term and late-term future led to a decrease in the carbon stocks in the NT topsoil. SOC stock significantly decreased under CT and MT. Since the NT was the tillage practice that could retain the topsoil carbon, it can be considered an appropriate approach to deal with climate change in comparable agro-ecosystems.
Application of ground motion model (GMM) considering rupture directivityto earthquake early warning (EEW) system in Taiwan
Authors: Weng Chin-Ting , Kuo Chun-Hsiang , Huang Hsin-Hua , Chao Shu-Hsien
Published: March 2024

          Taiwan is situated in Circum-Pacific Seismic Belt, located on the boundary between the Eurasian Plate and the Philippine Sea Plate. Therefore, it is necessary to evaluate the ground motion intensity in various seismic designs or seismic disaster assessments. Ground motion model (GMM) is employed for this purpose. In addition, earthquake early warning (EEW) system detects seismic activity in real-time and sends alert, providing people with a few seconds of warning before the arrival of damaging seismic waves, i.e., S-waves. Ground motions result in an increase in peak ground values (e.g. PGA and PGV) during a large magnitude earthquake, especially for the region near the forward rupture direction. Most of current GMMs do not consider the effect of rupture directivity, and thus ground motions in the direction of forward rupture propagation may be significantly underestimated. Accordingly, this study utilizes a GMM with consideration of a rupture directivity function (Chao et al. 2020; Convertito et al. 2012) to predict PGA and PGV for several local earthquakes with magnitude larger than 5.5. We estimate rupture direction (Jan et al. 2018) and then apply the above GMM incorporating rupture directivity effect to predict ground motions near real-time for an EEW system in Taiwan. Our aim is to enhance the accuracy of predicting ground motions, especially for the region near the forward rupture direction in which more critical damages are expected in comparison to the opposite direction.
Unusual fault kinematic behaviour and near-surface crustal stress variations before and during an earthquake series in the Vienna Basin (Austria) in spring 202
Authors: Melichar Rostislav , Baroň Ivo , Rowberry Matt , Jelének Jan , Sokol Ľuboš , del Puy Papí Isaba Maria , Freudenthaler Christiane , Hausmann Helmut , Plan Lukas , Grasemann Bernhard , Stemberk Josef , Schultz Richard A. , Bürgmann Roland
Published: March 2024

Short-term earthquake prediction remains one of the primary goals of seismotectonics. Here detailed observations of unusual fault kinematic behaviour and near-surface crustal stress variations are presented from before, during, and shortly after an earthquake series which culminated with two Mw 4.6 and 4.4 events near Breitenau, Vienna Basin, Austria, on 30 March 2021 and 19 April 2021, respectively. The oblique normal NNE-SSW trending Pitten Fault is exposed in Altaquelle Cave close to the southern margin of the Vienna Basin in the eastern Alps, which is known to have hosted several historical earthquakes of Mw = > 5. This cave has developed in Triassic marbles of the Central Alpine Permomesozoic. The observed branch of this active steeply dipping fault is associated with the seismogenic sinistral Vienna Basin Fault and the NE-SW trending Mur-Mürz Fault. To investigate the fault activity, TM71 moiré extensometers have been used to obtain precise three-dimensional records of fault kinematic behaviour at the micron scale while the recently developed SMB2018 protocol has been used to define the stress state associated with each fault reactivation event. The observations were then compared to the Copernicus European Ground Motion Service InSAR time series derived from Sentinel-1 data. From late 2018 to early 2021, the three-dimensional kinematic behaviour of the fault comprised a variety of different on-plane as well as out-of-plane hanging block displacements ranging in magnitude from 3 to 19 μm. Then, around the time of the earthquake series in 2021, four significant displacement events were recorded: (i) 0.186 mm along a vector of 186/-12° (i.e. upward) on 16 March; (ii) 0.615 mm along a vector of 177/-88° (upward) on 26 March; (iii) 0.066 mm along a vector of 013/26° (downward) on 30 March; and (iv) 0.022 mm along a vector of 308/54° (downward) on 11 May. The third of these events occurred on the same day as the largest earthquake. These events are all much larger than any other record of fault displacement recorded in the Eastern Alps since 2013. This contribution details this unusual fault displacement behaviour and compares the calculated stress states with both the focal solutions for each earthquake and InSAR maps of E-W and vertical ground motion. A comprehensive understanding of this important seismotectonic event helps to shed further light on potential earthquake precursory phenomena.
Evaluation of a tool to simulate high resolution mountain SWE from global datasets
Authors: Sourp Laura , Gascoin Simon , Pedinotti Vanessa , Jarlan Lionel , Alonso-González Esteban
Published: March 2024

Despite its significance, the snow water equivalent (SWE) is poorly characterized in many mountain regions due to i) a lack of in situ measurements and ii) the difficulty to measure the SWE directly from satellite observations. We developed a tool to simulate the spatial distribution of SWE at high resolution (typically 100 m) in any region of interest using SnowModel (Liston and Elder, 2006a, 2006b), global meteorological data (ERA5) and satellite observations of the snow cover fraction (SCF). Satellite observations are used to mitigate errors in the model parameterization and the meteorological forcings using the particle batch smoother  (Margulis et al., 2015). This method consists in computing N perturbed simulations on the whole hydrological season and transforming the simulated SWE in a simulated SCF. In this study, we used the formula linking the SWE and the SCF of the Noah Land Surface Model as the measurement operator. After that, the simulations are compared to remotely sensed SCF data and weighted according to their agreements with the observations. We implemented this data assimilation method with both MODIS and Sentinel-2 SCF data. We are testing it on the Bassies catchment in the French Pyrenees, and on the Tuolumne River Catchment in the Sierra Nevada, USA. In the Bassies catchment, we compare the results with snow depth maps from Pléiade satellites. We perturbed the precipitations with a log-normal law and found a very good agreement between the posterior simulated SCF and the observed one in Bassies as expected. However, the simulated snow depths in this catchment do not match the Pléiades snow depths observations. We added the perturbation of the air temperature with a normal law and found similar results. We also found a very small sensitivity of the posterior snow depth on the empirical parameters of the measurement operator. These results suggest that the SWE-SCF relationship may not be sufficiently informative in the study site of Bassiès.  We will present the extension of this work to the Tuolumne river basin where the Airborne Observatory provides SWE maps over a larger region.
On the decadal changes of Atlantic-Pacific interactions and the effects of external forcing
Authors: Karmouche Soufiane , Galytska Evgenia , Meehl Gerald A. , Runge Jakob , Weigel Katja , Eyring Veronika
Published: March 2024

We show the results of a study investigating the predominant role of external forcing in steering Atlantic and Pacific ocean variability during the latter half of the 20th (and early 21st) century. By employing the PCMCI+ causal discovery method, we analyze reanalysis data, pacemaker simulations, and a CMIP6 pre-industrial control run. The results reveal a gradual (multi)decadal change in the interactions between major modes of Atlantic and Pacific interannual climate variability from 1950 to 2014. A sliding window analysis identifies a diminishing El Niño-Southern Oscillation (ENSO) effect on the adjacent Atlantic basin through the tropical route, coinciding with the North Atlantic trending toward and maintaining an anomalously warm state after the mid-1980s. In reanalysis, this is accompanied by the prevalence of an extra-tropical pathway connecting ENSO to the tropical Atlantic. Meanwhile, causal networks from reanalysis and pacemaker simulations indicate that increased external forcing might have contributed to strengthening ENSO’s opposite sign response to tropical Atlantic variability during the 1990s and early 21st century, where warming tropical Atlantic sea surface temperatures induced La Niña-like easterly winds in the equatorial Pacific. The analysis of the pre-industrial control run underscores that modes of natural climate variability in the Atlantic and Pacific influence each other also without anthropogenic forcing. Modulation of these interactions by the long-term states of both basins is observed. This work demonstrates the potential of causal discovery for a deeper understanding of mechanisms driving changes in regional and global climate variability. Karmouche, S., Galytska, E., Meehl, G.A., Runge, J.,Weigel, K.,& Eyring,V. (2023b, in review). Changing effects of external forcing on Atlantic-Pacific interactions. EGUsphere, 2023, 1–36. https://doi.org/10.5194/egusphere-2023-18
Rift-inversion orogens are the place to be for natural hydrogen gas (H2) exploration
Authors: Zwaan Frank , Brune Sascha , Glerum Anne , Vasey Dylan A. , Naliboff John , Manatschal Gianreto , Gaucher Eric C.
Published: March 2024

Naturally occurring hydrogen gas (H2) represents a potentially major source of clean energy. It has been relatively overlooked so far but has gained more attention recently. The most promising mechanism for large-scale generation of such natural H2 is the serpentinization of mantle material as it reacts with water while it is brought into the “serpentinization window” (i.e., T = 200-350˚C) during mantle exhumation. We study such serpentinization-related natural H2 generation during rifting and subsequent rift inversion by means of numerical geodynamic models. In these numerical models we trace how, when, and where mantle material enters the serpentinization window, as well as when active, large-scale faults penetrate exhumed mantle bodies allowing for water circulation and serpentinization to occur.Although serpentinization-related natural H2 generation is a phenomenon best known from magma-poor rifted margins and slow spreading ridges, we find that volumes of natural H2 generated during inversion may be up to 20 times higher than during rifting, due to the colder thermal regime in rift-inversion orogenic environments. Moreover, suitable reservoirs and seals required for natural H2 accumulation are readily available in rift-inversion orogens, whereas they may not be present when serpentinization occurs in rift or drift settings. Our model results thus provide a first-order motivation to turn to rift-inversion orogens, rather than rifts and rifted margins, for natural H2 exploration. These model-derived insights are supported by indications of natural H2 generation in rift-inversion orogens such as the Western Alps, Pyrenees, and Caucasus.
A tale of two terrane boundaries – variable impact of terrane boundaries on rift geometry in the Great South Basin, New Zealand
Authors: Froemchen Malte , McCaffrey Ken , Phillips Tom , Allen Mark , van Hunen Jeroen
Published: March 2024

The evolution of continental rifts is influenced by the pre-rift rheology of the lithosphere and discrete lithospheric structures that segment the rift. The Great South Basin, offshore New Zealand, is a Cretaceous rift system that formed across heterogenous basement terranes which influence the rift architecture. Faults locally rotate or splay and segment along these terrane boundaries. While the impact of terrane boundaries on rift architecture is well understood, the temporal evolution of these rotated faults is poorly constrained. Here we use 3D reflection seismic data to investigate the timing and slip rate evolution of the rotated and segmented faults along two terrane boundaries. Our results show that these have a significant but variable impact on rift evolution and architecture: Faults in the Murihiku terrane show asymmetric throw-length profiles and are rotated along the terrane boundary to the Dun Mountain-Maitai terrane, as they detach into shallow crustal fabrics. Faults in the DMM terrane show less evidence of rotation and more symmetric throw-length profiles but are segmented along the DMM and Caples terrane boundary. The curving faults of the Murihiku terrane likely formed early on but remained as isolated segments only linking up during later stages of rifting when other faults became inactive. These results show the influence of the terrane boundaries was not only active early during initial segmentation but also during the linkage of curved fault segments in the later stages of rifting. These results may help understand the temporal evolution of lithospheric and crustal inheritance on rift evolution in other regions around the world like East Africa or North China.  
Generation of sea ice initial conditions for the next Météo-France seasonal forecasting system
Authors: Thottuvilampil Shahulhameed Fousiya , Beuvier Jonathan , Specq Damien
Published: March 2024

Research and development activities around the current Météo-France operational seasonal forecasting system (System 8) are underway to upgrade it to the next version (System 9), along with efforts to improve the initialization of its components. Among these components, sea ice is particularly challenging to initialize. At present, a coupled-nudged initialisation strategy, based on a high-resolution configuration of the CNRM-CM6 climate model, is employed to initialise the System 8, except for the sea-ice. In order to get initial states of sea ice that are consistent with the forecasting model, our procedure consists in making a preliminary continuous run where the ocean and sea ice models are integrated in stand-alone mode, with forcing at the surface from an atmosphere reanalysis.However, in the current operational System 8 – based on the NEMO 3.6 ocean model and the GELATO sea ice model – the initial states of sea ice generated with this procedure are not fully realistic. Results show that the sea ice thickness over the Arctic region in the System 8 initial states is underestimated compared to the reference data. Numerous sensitivity experiments were carried out with the current NEMOv3.6-GELATO system, leading to some minor improvements. Thus, an upgraded version of the ocean model (NEMO version 4.2) coupled to a new sea-ice component (SI3) has been tested (in stand-alone mode, not coupled to the atmosphere) to see if the use of more recent versions of ocean and sea-ice models leads to some improvements in the Arctic sea ice representation. The results are encouraging as the representation of sea ice variables in the Arctic is improved compared to the old version.This incites our team to foresee that System 9 will indeed incorporate the NEMO4.2 and SI3 models, and that the same initialization procedure as before (using these new models) will provide sea-ice initial states closer to those observed.  
Neutron imaging unveils heterogeneous flow patterns in homogeneous porous media and limitations of Darcy-Richards models
Authors: Sternagel Alexander , Rajyaguru Ashish Dinesh , Trevisan Luca , Loritz Ralf , Berkowitz Brian , Zehe Erwin
Published: March 2024

We applied neutron imaging techniques to unveil pore scale flow processes occurring during desaturation of a homogeneous, saturated sand pack. For this purpose, we used a small glass flow cell (2 cm x 2 cm x 0.1 cm) filled with pure, artificial S250 quartz sand. The pore space of the sand was initially fully saturated with double distilled water (DDW). The saturated flow cell was subjected to a series of suction phases with increasing suction tensions to extract water via a bottom outlet, controlled by a vacuum pump. In the first phase, a tension of 0.016 MPa (low suction) was applied for 248 min, followed by 1.14 MPa (mid suction) for 227 min, and finally, 10 MPa (high suction) for 397 min. Throughout the entire duration of the experiment, the flow cell was continuously exposed to neutrons. A back-end detector collected the neutron beams passing through the different matters (sand, water, air) contained in the flow cell and generated snapshot images of the internal pore structure and the water distribution with a pixel resolution of 5 µm at one-minute intervals.The resulting images revealed that water did not redistribute homogeneously during the desaturation of the flow cell, over dimensions of a few millimeters. Despite using “perfectly homogeneous” sand under initially fully water-saturated, controlled conditions, heterogeneous patterns of stable water pockets were observed inside the pore space of the sand, where water became immobilized.These experiments demonstrate that truly homogeneous flow does not occur even under controlled laboratory conditions in a “perfectly homogeneous” porous medium.Subsequent simulations of the experiments with common Darcy-Richards models showed that the macroscopic 1D desaturation time series of the flow cell could be realistically depicted. However, even after parameter calibration and the manual addition of heterogeneity, the microscopic, heterogeneous 2D distribution of water observed inside the flow cell could not be reproduced.This highlights limitations on the applicability of Darcy-Richards models, which may be effective at a macroscopic level but simultaneously fail to represent accurately the internal dynamics of the system. This insight is crucial for the application of Darcy-Richards models and the interpretation of their results.
Reconstructing the Earth in Deep-Time: A New and Open Framework for the PANALESIS Model
Authors: Franziskakis Florian , Vérard Christian , Giuliani Gregory
Published: March 2024

The Panalesis model (Vérard, 2019) was developed in a preliminary version according to concepts, methods and tools that follow the work carried out for more than 20 years at the University of Lausanne (Stampfli & Borel, 2002; Hochard, 2008). Although the techniques are relevant, development under ArcGIS® does not allow visibility and easy accessibility of the model to the scientific community.A major effort is therefore underway to migrate the entire model to an open source version using a FAIR approach for research software (Chue Hong et al., 2021). This migration concerns both the plate tectonic maps covering all the world over the entire Phanerozoic and part of the Neoproterozoic, but also the creation of paleoDEMs (global quantified topographies).The Panalesis model and its entire architecture is therefore currently migrated to QGIS (a free and open source geographic information system). TopographyMaker, the software designed to convert polylines from the reconstruction map into a points grid with elevation values is now working as a plugin on QGIS. The output palaeoDEMS will also be published according to the FAIR principles for scientific data management and stewardship (Wilkinson et al., 2016).The development and future refinements of TopographyMaker will enhance the Earth system modelling, especially coupling between models of different shells of the Earth such as atmospheric circulation, climatic evolution, and mantle dynamics. The topography is, for instance, considered a first order controlling factor for CO2 evolution over geological timescales, through silicate weathering (MacDonald et al., 2019).
A slice through time — securing timelines of past climate, global volcanism and human societies
Authors: Sigl Michael
Published: March 2024

Major efforts have been made in recent decades to decipher the climate of the past and its drivers with the help of proxy archives. Reconstructions of past climate variations are of immediate societal relevance because they serve as a baseline for anthropogenic climate change, and help us understand how past societies coped (or failed to cope) with extreme climate events. Good paleoclimatology, however, relies on ever more precise and accurate dates. While many proxy archives provide continuous year-by-year sequences going back many thousands of years, ambiguities in their interpretation introduce time uncertainty which increases over time. As a consequence, natural climate variability is underestimated when time-uncertain climate reconstructions are combined.Through the use of "Miyake events" — novel time markers that are accurate to the year, globally distributed and detectable in different climate archives — it has recently become possible to better date and synchronize some of these climate archives, notably the polar ice-core records. The revised dating of ice cores from both Greenland and Antarctica combined with technological advances based on real-time continuous flow analysis techniques has shed new light on a prominent impact of volcanic eruptions on past climate and human societies. In this talk, I will highlight how we can date ancient eruptions, (sometimes to the season), geochemically identify their provenance and quantify their climate impact potential through emissions of sulfuric gases using large networks of ice cores. Case studies include prominent eruptions from Vesuvius or Santorini as well as eruptions largely unknown to the general public, for example from Alaska. I will discuss linkages to precisely dated proxies (e.g. tree-rings) and documentary records to demonstrate the accuracy of the new ice-core chronologies and to delineate climatic and societal responses to external shocks caused by major volcanic eruptions. In my concluding remarks, I will show how such lessons from the past can help to improve our understanding of past natural climate variability and to quantify global risks arising from volcanic activity in the future.
Physical erosion rates in Ogooué and Mbei Rivers (Gabon, Western Central Africa): insights for Cratonic Catchments.
Authors: Regard Vincent , Carretier Sébastien , Jean-Sébastien Moquet , Choy Sandrine , Blard Pierre-Henri , Bogning Sakaros , Mbonda Auguste Paulin , Mambela Emmanuel , Paiz Marie Claire , Séranne Michel , Charreau Julien , Rouby Delphine , Bouchez Julien , Gaillardet Jérôme , Braun Jean-Jacques
Published: March 2024

We measured the long term physical denudation of the Ogooué River catchment using 10Be. These measurements are averaged over 25-200 ka (average 40 ka), depending on the physical denudation rate. The denudation rate of the Ogooué River catchment is slow (38 t/km2/a, 15 m/Ma), slightly higher than the Equatorial West Africa (from Senegal to Angola, 26 t/km2/a, 10 m/Ma). Physical denudation and chemical weathering fall within the same order of magnitude. Thus, although low, chemical weathering, is substantial compared to physical denudation, its contribution is likely over 30% of the total denudation.Denudation rates are spatially variable (from 10 to 60 t/km2/a) within this large Ogooué River catchment. Over the long term, this variability exhibits a fairly close match of physical denudation/chemical weathering, except in the Batéké Plateaux area, because they are made up of already weathered detrital material and their modern flux of solutes is therefore very low (~9.5 t/km2/a). The spatial distribution is similar to the one described in Moquet et al. (2021)'s work, i.e. the southern part of the catchment is denuding twice as fast as the northern part. We show here that the whole picture did not vary much since 100 ka, as shown by both methods giving consistent results. Faster denudation in the south of the catchment may be related to some more uplift than in the north caused by the south African superswell. 