bluuebunny/crossref_metadata_2025 huggingface dataset:
Recognizing distinctiveness of SSP3-7.0 for use in impact assessments
Authors: Shiogama Hideo , Fujimori Shinichiro , Hasegawa Tomoko , Hayashi Michiya , Hirabayashi Yukiko , Ogura Tomoo , Iizumi Toshichika , Takahashi Kiyoshi , Takemura Toshihiko
Published: March 2024

Because recent mitigation efforts have made the upper-end scenario of the future GHG concentration (SSP5-8.5) highly unlikely, SSP3-7.0 has received attention as an alternative high-end scenario for impacts, adaptation, and vulnerability (IAV) studies. However, the ‘distinctiveness’ of SSP3-7.0 may not be well-recognized by the IAV community. When the integrated assessment model (IAM) community developed the SSP-RCPs, they did not anticipate the limelight on SSP3-7.0 for IAV studies because SSP3-7.0 was the ‘distinctive’ scenario regarding to aerosol emissions (and land-use land cover changes). Aerosol emissions increase or change little in SSP3-7.0 due to the assumption of a lenient air quality policy, while they decrease in the other SSP-RCPs of CMIP6 and all the RCPs of CMIP5. This distinctive high-aerosol-emission design of SSP3-7.0 was intended to enable climate model (CM) researchers to investigate influences of extreme aerosol emissions on climate. Here we show that large aerosol emissions in SSP3-7.0 significantly suppress future increases in precipitation. We recommend IAV researchers to compare impact simulations at the same warming level between SSP3-7.0 and SSP5-8.5 to examine the effects of aerosols in the case that such analyses are adequate. We also recommend ScenarioMIP for CMIP7 to exclude scenarios with extreme policies of aerosols (and land-use land-cover changes) from Tier 1 experiments and instead include them in Tier 2. Reference: Shiogama, H., et al. Nat. Clim. Chang. 13, 1276–1278 (2023). https://doi.org/10.1038/s41558-023-01883-2
Attribution using analogues: a case study of the Western European flood event of July 2021 
Authors: Thompson Vikki , Coumou Dim , Philip Sjoujke , Kew Sarah , Pinto Izidine
Published: March 2024

In July 2021 a cut-off low pressure system brought extreme precipitation to Western Europe. Record daily rainfall totals led to flooding that caused loss of life and substantial damage to infrastructure in Germany, Belgium, and the Netherlands. By identifying flow analogues – dynamically similar events - in both reanalysis data and large ensembles of climate model simulations we can investigate how the dynamics involved in this event are changing through time. Analogue methods are increasingly used in event attribution, we highlight considerations that must be made when using such methods. For July 2021, we show that similar low pressure systems are occurring more frequently, and the lows are deepening through time. We find some analogues persist for much longer than was seen in July 2021. These dynamical changes effect surface impacts of such events. Such unprecedented events will become increasingly likely in a warming climate, and society must adapt to reduce future impacts. 
Benefits of increasing soil organic carbon to reduce drought stress in maize under climate change
Authors: Turek Maria Eliza , Holzkämper Annelie , Nemes Attila
Published: March 2024

Increasing frequencies and intensities of drought periods are likely to aggravate conflicts between agricultural demands and other human and ecological demands for water resources. Improving the natural soil water retention capacity can help to defuse these conflicts and at the same time strengthen climate mitigation, biodiversity, and food security. Increasing soil organic carbon content (SOC) is seen as a promising negative emission technology for the agricultural sector, with the co-benefit of potentially increasing the soil water retention capacity. We tested how different levels of SOC at varying soil depths influence in the transpiration reduction caused by drought stress (Treddry) in maize under current and future climatic conditions. We used the SWAP (Soil Water Atmosphere Plant) model validated utilizing information from a long-term lysimeter for a typical Swiss soil and applied it at three distinct climatic regions. A pedotransfer function (PTF) was used to indirectly assess the effects of SOC on soil hydraulic properties that affected the drought stress. Study findings revealed that increasing SOC down to 65 cm depth is beneficial to reduce drought limitations in maize. These benefits are minimal if SOC is only increased in the top 25 cm but become considerable if SOC is increased down to 65 or 135 cm depth. With a 2% addition of SOC down to 65 cm depth, a considerable average transpiration gain of 40 mm can be reached. It appears that a greater or deeper SOC addition would not return substantial extra benefits in terms of offsetting more crop drought stress rooting in the changing climate.
Unravelling metal mobilising processes in the Kolumbo volcano Au-rich SMS using Pb isotopes.
Authors: Hector Simon , Ahmad Qasid , Patten Clifford G. C. , Chiaradia Massimo , Kilias Stephanos , Nomikou Paraskevi , Kolb Jochen
Published: March 2024

Gold-rich seafloor massive sulfides (SMS) form in various marine hydrothermal environments, including continental volcanic arcs, where magmatic fluids may contribute significantly to the metal budget of the hydrothermal system. To track the origin of metals and unravel the mineralising processes at play in Au-rich SMS formation (i.e. hydrothermal leaching of country rocks or magmatic degassing), we investigated the volcanic/basement rocks and Au-rich SMS of the Kolumbo submarine volcano (Greece). We combine in-situ Pb isotope analysis of the sulphide mineralisation and whole rock Pb isotope analysis of volcanic and basement rocks. During magmatic evolution, crustal material assimilation slightly shifts Pb isotope ratios toward more radiogenic values defining a differentiation trend from andesite to rhyolite. The mineralisation, dominated by pyrite with episodic galena, sphalerite, chalcopyrite and Sb-Pb sulfosalts formation, has Pb isotopes ratios pointing toward an igneous source. Galena and Sb-Pb sulphosalts have Pb isotopes ratios similar to volatile-saturated trachytic magma indicating Pb mobilisation during magmatic degassing, while Pb isotopes ratios in pyrite matches volatile-poor post-degassing rhyolite, suggesting Pb mobilisation by hydrothermal leaching of rhyolite. Lead isotope ratios reveals that Pb at Kolumbo is sourced from igneous rocks but the mechanisms for metal transfer vary from rhyolite leaching by hydrothermal fluid circulation to episodic input of magmatic fluid able to provide Ag, As, Au, Cu, Hg, Pb, Sb, Tl in addition to Pb. The magmatic evolution of Kolumbo highlights the diversity and complexity of metal mobilising magmatic-hydrothermal processes involved in Au-rich SMS formation.
Comparative Analysis of a LSTM and a Rainfall-Runoff Model for Catchment Runoff Simulation: Advancing Hydrological Modelling and Forecasting
Authors: Hotzel Anika , Mudersbach Christoph
Published: March 2024

Hydrological modelling is an important tool for understanding and predicting runoff behaviour in catchments. It is essential for flood risk management and flood forecasting. This study conducts a comparative analysis of two modelling approaches: a Long Short-Term Memory (LSTM) neural network model and a conventional rainfall-runoff model. Both models are used to simulate runoff dynamics in a catchment in Bavaria, Germany.LSTM models are known for their ability to capture temporal dependencies and nonlinear relationships in sequential data. This research aims to comprehensively evaluate and compare the performance, accuracy, and predictive capabilities of the physical rainfall-runoff model widely used in hydrology against the LSTM model. The objective is to replicate the intricate processes governing rainfall-induced runoff. This study analyses the ability of the LSTM model to predict runoff patterns by leveraging historical hydrological data and meteorological inputs. The model learns from temporal sequences of precipitation and other relevant factors. The traditional rainfall-runoff model, which operates on established hydrological principles and parameterizations, is also assessed for its accuracy in simulating runoff within the same catchment. The comparison includes assessments of prediction accuracy, model robustness under varying conditions, computational efficiency, and the ability to capture the complex non-linear relationships inherent in hydrological processes.The results of this study have important implications for the further development of hydrological modelling techniques. Understanding the comparative strengths and limitations of the LSTM model against the conventional rainfall-runoff model provides valuable insights for improving the accuracy and reliability of runoff predictions. Such information can improve decision making in flood risk management, assist in more accurate flood forecasting and help reduce the loss of human life. By identifying the comparative effectiveness of these modelling approaches in reproducing the complex dynamics of runoff, this research aims to advance the field of hydrological modelling and pave the way for more robust and accurate prediction tools.
The 2023 record low Antarctic sea ice traced to synergistic influences of preconditioning, wind-induced transport and the ice albedo feedback
Authors: Wang Jinfei , Massonnet François , Goosse Hugues , Luo Hao , Yang Qinghua , Barthélemy Antoine
Published: March 2024

Antarctic sea ice extent (SIE) reached a new record low of 1.79 million km2 on 21 February 2023, 38% lower than the climatological average. In this study, we trace this record back to its possible origins by providing a detailed view on the evolution of the coupled ocean-atmosphere-sea ice system during the 12 months that preceded the event (March 2022 to February 2023). The impact of preceding winter and spring conditions on the summer minimum is assessed with the help of observations, reanalyses, and output from a regional ocean-sea ice coupled model NEMO3.6-LIM3. We find that the 2022-2023 annual cycle was characterized by consistently low SIE values throughout the year preceding the record, by anomalously high SIE melting rates in December 2022, and by circumpolar negative SIE anomalies in almost all basins of the Southern Ocean in February 2023. Through autumn and winter (March to August 2022), advection-induced positive air temperature anomalies inhibited the development of sea ice in the Weddell and Bellingshausen Seas, which preconditioned an ice-free state in the Bellingshausen Sea as early as October 2022. Concurrently, strong southerly winds in the Eastern Ross Sea caused by an anomalously deep Amundsen Sea Low in spring (September to November) transported significant volumes of sea ice northward, contributing to severe melting offshore in December and, through increased divergence near the coast, triggered the ice-albedo feedback onshore. As a consequence, a coastal polynya appeared in the western part of the Amundsen Sea due to stronger surface sea ice melting. This ice-albedo feedback was unusually active in late 2022 and favored accelerated melt towards the minimum in February 2023. This study highlights the impacts of multifactorial processes during the preceding seasons to explain the recent summer sea ice minima.
Understanding past changes in Australian droughts and their drivers
Authors: Grant Matt , Ukkola Anna , Vogel Elisabeth , Hobeichi Sanaa , Pitman Andy , Hartley Andrew
Published: March 2024

Australia is frequently exposed to considerable impacts from severe and widespread droughts. Despite this, a comprehensive understanding of the past trends and drivers of Australian droughts remains elusive. Existing studies have often characterised past trends based on changes in mean values rather than the extremes. However, given Australia’s exceptionally variable climate, this may fail to capture the full nature of the country’s drought trends. Furthermore, studies often rely on a limited number of drought indicators and may not encompass the diverse meteorological, hydrological and ecological conditions contributing to drought.This work explores past drought trends in Australia using multiple drought indicators. We analyse changes in traditional drought metrics, including precipitation, runoff and soil moisture, defining droughts as time periods below the 15th percentile. We complement these metrics with an impacts-based drought indicator built from government drought reports using machine learning. We explore the drivers of drought trends using explainable machine learning methods, and consider multiple drivers including large-scale climate features, land surface properties and past conditions. Using a diverse range of metrics allows for a more comprehensive analysis of drought changes experienced over the past decades and will provide greater insight into the main drivers behind Australian droughts.
Direct Estimation of Carbon Emissions from High Latitude Fires: The Adapted FREM Approach
Authors: Maslanka Will , Wooster Martin
Published: March 2024

Landscape fires are a widespread natural phenomenon that directly influences carbon cycling through the combustion of organic material. Space-based remote sensing, including Active Fire (AF), remains the only way to estimate wildfire activity accurately on the regional-to-global scale. Fire emission inventories generally fall into two categories. “Bottom-up” methodologies rely on observations of AF counts, Fire Radiative Power (FRP), or burned area to estimate the amount of biomass burned, or “Top-down” methodologies, which directly relate observations of FRP to landscape fire emission estimates. Bottom-up methods tend to have a reliance on uncertain parameters, such as pre-fire fuel load and combustion completeness, or a conversion factor between FRP and fuel consumption rate. The Fire Radiative Energy Emission (or FREM) approach is one such top-down methodology that has removed such a reliance, by directly relating FRP to observed rates of emissions, such as CO or aerosols, but has so far been used with geostationary FRP data only. Whilst very effective at lower latitudes, due to the poor spatial resolution and extreme viewing geometry of geostationary data at higher latitudes, the approach is not applicable for fires in this region in its current format. However, by using polar orbiting FRP data and making use of the high latitude orbital convergence, this study looks to adapt the FREM approach to deliver direct estimation of carbon emissions for high latitude (>60°N) landscape fires. We use direct observations of FRP, from Suomi-NPP, NOAA-20 and MODIS, along with observations of Total Column Carbon Monoxide from TROPOMI onboard Sentinel-5P. A series of cloud-free plumes and associated FRP data were identified in Deciduous and Evergreen Needleleaf biomes in North America and Russia in the summers of 2019 – 2023. The resulting emission coefficients and emission totals were compared to pre-existing top-down and bottom-up emission coefficients and totals from the FEER, GFAS, and GFED inventories for high latitude fires between 2018-2023. This adapted FREM approach is shown to provide direct emission estimates without recourse to significant assumptions and can do so in real time – opening up a new avenue for real-time fire emission estimation at high latitudes.
Effect of horizontal flow on the age field along the Dome C – Little Dome C flow line
Authors: Chung Ailsa , Parrenin Frédéric , Mulvaney Robert , Vittuari Luca , Frezzotti Massimo , Eisen Olaf
Published: March 2024

We present a 2.5D pseudo-steady state inverse model applied to the flow lines from Dome C to LDC and from Dome C to North Patch (an area ~10km NE of Dome C). The model is constrained by radar horizons dated from 10-476 ka using the EPICA Dome C (EDC) ice core. We interpolate and extrapolate the age-depth relationship using these horizons. The simplicity of our 2.5D numerical integration scheme results in an efficient computation time allowing us to use inverse methods to determine an average accumulation rate over the past 800 ka, a mechanical ice thickness and the thinning parameter which describes the shape of vertical velocity profile. The inverted mechanical ice thickness allows us to infer either the melt rate or the thickness of a layer of stagnant basal ice.The model shows that the EDC-LDC flow line is dominated by melting on in the upstream sections, and further downstream, there is a thick layer of stagnant ice over the LDC mountainous bedrock relief. Our results show to what extent the Beyond EPICA - Oldest Ice drill site is affected by horizontal flow from upstream at the dome and the implications for the age-depth profile of the ice core currently being drilled. The deepest oldest ice at the drill site, comes from 10-15 km upstream. However, the differences between the model and observations cannot be fully explained by horizontal flow. We also show that North Patch is a promising potential oldest ice site but more high-resolution radar surveys would be required to constrain this. This model could be applied to other areas of Antarctica of Greenland such as the flow lines from Dome Fuji to EDML or at from Ridge B to lake Vostok or from GRIP to EGRIP.This work is part of the network of DEEPICE PhD projects associated with the Beyond EPICA drilling project which aims to recover a continuous 1.5 million year old ice core from Little Dome C in Antarctica. 
Impact of AMV on rainfall intensity distribution and timing of theWest African Monsoon in DCPP-C-like simulations
Authors: Mohino Elsa , Monerie Paul-Arthur , Mignot Juliette , Diakhaté Moussa , Donat Markus , Roberts Christopher David , Doblas-Reyes Francisco
Published: March 2024

Previous studies agree on an impact of the Atlantic Multidecadal Variability (AMV) on total seasonal rainfall amounts over the Sahel. However, whether and how AMV affects the distribution of rainfall or the timing of the West African Monsoon is not well known. Here we seek to explore these impacts by analyzing daily rainfall outputs from climate model simulations with an idealized AMV forcing imposed in the North Atlantic, which is representative of the observed one. The setup follows a protocol largely consistent with the one proposed by the Component C of the Decadal Climate Prediction Project (DCPP-C). We start by evaluating model's performance in simulating precipitation, showing that models underestimate it over the Sahel, where the mean intensity is consistently smaller than observations. Conversely, models overestimate precipitation over the Guinea Coast, where too many rainy days are simulated. In addition, most models underestimate the average length of the rainy season over the Sahel, some due to a too late monsoon onset and others due to a too early cessation. In response to a persistent positive AMV pattern, models show an enhancement in total summer rainfall over continental West Africa, including the Sahel. Under a positive AMV phase, the number of wet days and the intensity of daily rainfall events are also enhanced over the Sahel. The former explains most of the changes in seasonal rainfall in the northern fringe, while the latter is more relevant in the southern region, where higher rainfall anomalies occur. This dominance is connected to the changes in the number of days per type of event: the frequency of both moderate and heavy events increases over the Sahel’s northern fringe. Conversely, over the southern limit, it is mostly the frequency of heavy events which is enhanced, affecting the mean rainfall intensity there. Extreme rainfall events are also enhanced over the whole Sahel in response to a positive phase of the AMV. Over the Sahel, models with stronger negative biases in rainfall amounts compared to observations show weaker changes in response to AMV, suggesting systematic biases could affect the simulated responses. The monsoon onset over the Sahel shows no clear response to AMV, while the demise tends to be delayed and the overall length of the monsoon season enhanced between 2 and 5 days with the positive AMV pattern. The effect of AMV on the seasonality of the monsoon is more consistent to the west of 10ºW, with all models showing a statistically significant earlier onset, later demise and enhanced monsoon season with the positive phase of the AMV. Our results suggest a potential for the decadal prediction of changes in the intraseasonal characteristics of rainfall over the Sahel, including the occurrence of extreme events.
Impacts of demersal fishing on sedimentary organic matter: a global meta-analysis.
Authors: Sciberras Marija , Paradis Sarah , Tiano Justin , De Borger Emil , Bradshaw Clare , Morys Claudia , Pusceddu Antonio , Ennas Claudia , Soetaert Karline , Puig Pere , Masque Pere
Published: March 2024

Marine sediments represent a hot spot of ecosystem services, but their integrity is increasingly put at risk by anthropogenic disturbance, most notably by demersal fisheries. The need for global action to minimize the impacts of destructive fishing techniques on the marine environment is urgent. The urgency to act, however, needs to be met with caution, as scientists are pushed for action, global predictions of trawling impacts are tempting, yet poor validation and oversimplified assumptions can lead to large uncertainties. We visit the scientific literature on trawl studies to map out current evidence from the literature and report on a global meta-analysis to quantify the effects of demersal fishing on sedimentary and biogeochemical properties. Studies examining the direct impacts of bottom fishing revealed significant reductions in total organic carbon (TOC; -10%), chlorophyll-a (Chl-a, -10%), phaeopigments (-21%) and proteins (-24%), and largest impact was detected on surficial sediment (0-2 cm). Implications of methodological biases as a result of inappropriate sampling in trawl studies and the importance of context-dependency for effect size is flagged up. Environmental parameters such as bottom current velocity and surface primary productivity significantly influenced both the direction and magnitude of fishing effects. We highlight where the lack of evidence lies that might create bias in regional and global models that require empirical data for validation. The objective is to summarize current knowledge and to direct future studies towards more robust analysis of the impacts of bottom trawling, which will provide a basis of sound advice to fisheries managers and policy makers.
On the limit imposed by variable atmospheric pressure for the observation of small terrestrial rotations around horizontal axes
Authors: Widmer-Schnidrig Rudolf , Brotzer Andreas
Published: March 2024

Ubiquitous acoustic gravity waves in the atmosphere lead to elastic deformations of the Earth’s surface via ambient barometric pressure variations at ground level. The induced ground deformations are composed of vertical and horizontal displacements as well as ground tilts or equivalently ground rotations around horizontal axes. To make inferences about background levels of rotational ground motions we exploit the fact that ground tilts are sensed by both suitably oriented gyroscopes, as well as horizontal component accelerometers through tilt coupled gravity.  Based on 20 years of data from the Global Seismic Network (GSN) we estimate coherence and admittance between ambient atmospheric pressure and horizontal acceleration from collocted sensors.Since atmospheric acoustic gravity waves propagate too slowly to efficiently excite Rayleigh waves in the Earth, we attribute horizontal accelerations which are coherent with pressure to tilt coupled gravity. Based on this line of reasoning and by restricting the analysis to time windows with high coherence, we can estimate lower bounds of background tilt and background rotation rate for all GSN stations and for the GSN as a whole. We find that below 20mHz and in the least noisy time windows the  pressure induced background rotation rate is 30dB higher than similar estimates based on the assumption that the terrestrial noise floor for rotations around a horizontal axis is defined by Rayleigh wave motion.A notable consequence of the above findings is that for frequencies below 20 mHz  atmospheric pressure induced ground tilts lead not only to the well established large difference between background noise levels for vertical and horizontal seismic accelerations, but also for rotations around vertical and horizontal axes.  We will present preliminary new rotational low noise models valid for frequencies below the band of the marine microseisms. The caveat for such models is that they are drived from inertial seismometers and not from gyroscopes. Data from the ROMY gyroscope are analyzed in a companion poster by Brotzer et al. in this same session SM3.3
Non-stationary design rainfalls for Australia
Authors: Jayaweera Lalani , Wasko Conrad , Nathan Rory , Johnson Fiona
Published: March 2024

Action needs to be taken in response to the changes in future flood risk due to the impact of global warming on the magnitude and frequency of extreme rainfalls. Projected changes in extreme rainfalls can be used to estimate the associated changes in design flood estimates using Intensity-Frequency-Duration (IFD) curves in combination with event-based flood models. IFD curves are estimated from records of historical annual maxima across different storm durations and exceedance probabilities. Past studies investigating changes in extreme rainfall across Australia have been limited in scope as they have focused on single durations, single exceedance probabilities, or limited regional extents. This means that we do not yet have a comprehensive understanding of how projected changes in extreme rainfalls impact on IFD curves.Here, to fill this gap, we investigate the changes in extreme rainfall changes across different storm durations and exceedance probabilities across 42 stations which span the entire continent of Australia. We begin with examining the trend in annual maximum rainfall across 16 different storm durations (6 min to 7 day) using the Theil-Sen slope estimator, testing for statistical significance using the Mann-Kendall test. To extrapolate 1% annual exceedance probability, we fit non-stationary Generalized Extreme Value Distributions (GEVs) at each site. Non-stationarity was assessed by varying the location parameter, varying the scale parameter, and varying both the location and scale parameters as a linear trend in time.We find that the short duration (1 hr and 1 day) show fewer positive trends with some sites exhibiting negative trends. Based on Akaike Information Criteria, the GEV models which varied either the location parameter, or both the scale and location parameters, were found to be superior. However, when changes in quantile estimates were examined for rare exceedance probabilities (up to the 1 in 100 AEP), it was found the GEV model which only varied the location parameter was unable to capture the increased rate of change in extreme rainfalls. Accordingly, we conclude that changes in extreme rainfalls is best represented by non-stationary models that incorporate changes in both location and scale parameters.
Strong (Mw>6.0) earthquakes along the KTFZ: implications for recurrence pattern and seismic coupling
Authors: Papadimitriou Eleftheria , Karakostas Vassilios
Published: March 2024

The Kefalonia Transform Fault Zone (KTFZ) in central Ionian Islands (Kefalonia and Lefkada Islands), Greece, exhibits the fastest rates of relative plate motion in the Mediterranean. It constitutes an active boundary and comprises five manor fault segments with a total length of nearly 120km, and are characterized by fast long–term rates of displacements of about ~25mm/yr for Kefalonia segments and ~15 mm/yr for Lefkada segments. Strike slip faulting with moment magnitudes Mw up to 7.0 characterizes the largest earthquakes, whereas the five almost along strike faults have been the sites of numerous earthquakes of moment magnitude, Mw, 5.0–7.0 during the past 50 years. The KTFZ in its entire length is much more active at the Mw>6.0 level than a comparable length of either the North Aegean Trough or Corinth rift, which are the most fastly deforming areas in the area of Greece. Alteration of active periods comprising multiple earthquakes with much longer quiescent periods is the mode of strong earthquake occurrence, with prevailing clustering over the period when historical information is available. The fast rate of plate motion, maximum size of earthquakes and relatively short repeat times make these fault segments suitable to seek for recurrence behavior that approaches quasi–periodic and its potential implications to the cyclic mode of seismogenesis. Recurrence of M6.0 earthquakes along nearly the same fault segment is attempted after evaluating the location of the historical events, based on all available macroseismic descriptions. These estimations are then compared with computed simulated catalogs.The computed depths of earthquakes along the KTFZ are accurate enough to ascertain centroid depths as indicators of the downdip width of seismic faulting. With aftershock relocation we constrained the seismogenic layer in Kefalonia and Lefkada segments equal to 14 km (between depths of 3 and 17 km) and 10 km (between depths of 5 and 15 km) respectively, corresponding to downdip widths of 19 and 12 km, respectively. We compared these constraints with the calculated downdip width from a segment’s length along strike, moment release and relative plate motion ‘assuming’ full seismic coupling. The good correlation between the two support the high degree of coupling along the KTFZ.Acknowledgments: Funded by the European Union. Views and opions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or European Commission – Euratom. Neither the European Union nor the granting authority can be held responsible for them.  
Tracking dune blowouts to constrain prehistoric droughts in the Nebraska Sand Hills (Great Plains, USA)
Authors: Kreutzer Sebastian , Schmidt Christoph , Kadereit Annette , Hanson Paul
Published: March 2024

Droughts are amongst the most significant natural hazards in the central and southern Great Plains (USA). Chronologies of droughts and related dune activity phases in the Great Plains are paramount for understanding the frequency and magnitude of these potential risks. Beyond historical records, the timing and magnitude of droughts can be revealed only from sediment archives. Our joint DFG/SNF project, CONSTRAIN, aims to provide a new, accurate, and precise temporal placement of prehistoric droughts in the Great Plains, specifically the Nebraska Sand Hills, over the last 1,500 years. We combine methodological research (zircon luminescence dating, luminescence screening) with high-resolution quartz OSL dating to better understand the regional landscape dynamics. Our collaboration is currently in a pilot phase, performing the first methodological tests and identifying suitable archives for dating.In our first field season, we sampled sand blowouts in the Nebraska Sand Hills identified from LiDAR data. These widespread crater-like depressions (Stubbendieck et al., 1989) are similar to modern blowouts but are grass-covered, suggesting they are likely prehistoric. Still, they remain poorly studied. The blowouts are deflation hollows that seem unrelated to anthropogenic activity or disturbance through wild animals. Instead, they likely formed from drought events that resulted in aeolian deflation on dune crests, but they were either of lower magnitude or shorter-lived than droughts that reactivated the dunes that last moved between 1,000 to 600 years ago (Mason et al., 2004; Miao et al., 2007; McKean et al., 2015).Our contribution presents field luminescence screening results from 141 samples and the first optically stimulated luminescence (OSL) quartz ages derived from standard measurements testing the hypothesis that the naturally occurring blowouts are related to partial dune reactivation phases between 800 to 200 years ago.ReferencesMason, J. A., Swinehart, J. B., Goble, R. J., and Loope, D. B.: Late-Holocene dune activity linked to hydrological drought, Nebraska Sand Hills, USA, The Holocene, 14, 209–217, https://doi.org/10.1191/0959683604hl677rp, 2004.McKean, R. L. S., Goble, R. J., Mason, J. B., Swinehart, J. B., and Loope, D. B.: Temporal and spatial variability in dune reactivation across the Nebraska Sand Hills, USA, The Holocene, 25, 523–535, https://doi.org/10.1177/0959683614561889, 2015.Miao, X., Mason, J. A., Swinehart, J. B., Loope, D. B., Hanson, P. R., Goble, R. J., and Liu, X.: A 10,000-year record of dune activity, dust storms, and severe drought in the central Great Plains, Geology, 35, 119–4, https://doi.org/10.1130/g23133a.1, 2007.Stubbendieck, J., Flessner, T. R., and Weedon, R.: Blowouts in the Nebraska Sandhills: The Habitat of Penstemon haydenii, Proceedings of the North American Prairie Conferences, 223–225, 1989.
TRACING 2021-2024 – Feedback on international events to develop novel strategies of sediment tracing in catchments and river systems
Authors: Evrard Olivier ,   TRACING Event organisers and participants
Published: March 2024

Several innovative techniques have been developed recently opening up new avenues to establish the assessment of sediment flux in the critical zone. These innovative techniques include the tracing or “fingerprinting” methods to identify the sources and quantify the dynamics of sediment and particle-bound contaminants. However, the use of these techniques is often associated with several methodological and statistical limitations, that are often reported although rarely addressed in the framework of concerted actions taken at the level of the international scientific community.This presentation will present the main outcomes of the Thematic School organised in 2024 and the Scientific Meeting Days organised in 2022 and 2023 as a follow-up of a first training week organised in 2021 to bring together international experts working on these topics together. Based on the publication of an opinion paper (https://link.springer.com/article/10.1007/s11368-022-03203-1), new strategies to publish and disseminate sediment tracing databases will be presented. An example of formatted dataset will be given, with the objective to test research hypotheses based on multiple datasets adopting the same format of data/meta-data. Other perspectives regarding improvements of the sediment fingerprinting method in terms of modelling, tracer options and selection will also be presented.
Impacts of extreme land-use change on wind profiles and wind energy according to regional climate models  
Authors: Wohland Jan , Hoffmann Peter , Lima Daniela C.A. , Breil Marcus , Asselin Olivier , Rechid Diana
Published: March 2024

Humans change the climate in many ways, for example, by emitting greenhouse gases or by changing land-use. While studies typically investigate the joint effects of human activity, we here isolate the impact of afforestation and deforestation on winds in the lowermost 350 m of the atmosphere to better understand the role of forests in large-scale wind energy assessments. We use vertically resolved sub-daily output from two regional climate models and compare two extreme scenarios from the LUCAS simulations (Davin et al., 2020). Our results show that afforestation lowers wind speeds by more than 1 m/s in many locations across Europe even 300 m above ground and thus matters at wind turbine hub heights. While adapting the parameters in standard extrapolation allows to capture long-term mean winds well, it remains insufficient to compute wind energy potentials as it fails to capture essential spatio-temporal details, such as changes in the daily cycle. We therefore follow an alternative approach that leverages the vertical resolution of the regional climate models to account for wind profile complexity. Doing so, we report strong changes in wind energy capacity factors due to afforestation and deforestation: they change by up to 50 % in relative terms. Our results confirm earlier studies that land use change impacts on wind energy can be severe and that they are generally misrepresented with common extrapolation techniques. References:Davin, E. L., Rechid, D., Breil, M., Cardoso, R. M., Coppola, E., Hoffmann, P., Jach, L. L., Katragkou, E., de Noblet-Ducoudré, N., Radtke, K., Raffa, M., Soares, P. M. M., Sofiadis, G., Strada, S., Strandberg, G., Tölle, M. H., Warrach-Sagi, K., and Wulfmeyer, V: Biogeophysical impacts of forestation in Europe: First results from the LUCAS Regional Climate Model intercomparison, Earth Syst. Dynam., 11, 183–200, 2020, https://doi.org/10.5194/esd-11-183-2020, 2020Preprint:Wohland, J., Hoffmann, P., Lima, D. C. A., Breil, M., Asselin, O., and Rechid, D.: Extrapolation is not enough: Impacts of extreme land-use change on wind profiles and wind energy according to regional climate models, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2023-2533, 2023
Anticipating critical transitions in multi-dimensional systems driven by time- and state-dependent noise
Authors: Morr Andreas , Riechers Keno , Rydin Gorjão Leonardo , Boers Niklas
Published: March 2024

When approaching a one-parameter bifurcation, the feedbacks that stabilise the initial state weaken and eventually vanish; a process referred to as critical slowing down (CSD). This motivates the use of variance and lag-1 auto-correlation as indicators of CSD in order to anticipate bifurcation-induced critical transitions. Both indicators require a prior dimension reduction to a one-dimensional time series. The use of variance is further limited to time- and state-independent driving noise, strongly constraining its generality. Here, we propose a data-driven approach based on deriving a multi-dimensional Langevin equation to detect local stability changes and anticipate bifurcation-induced transitions in systems with generally time- and state-dependent noise. Our approach substantially generalizes the conditions underlying existing early warning indicators, which we showcase in the example of a two-dimensional predator-prey model. This reduces the risk of false and missed alarms significantly and allows for a more holistic understanding of the multi-dimensional system at hand.
Comparison and analysis of drought indices SPI and SPEI for Belgrade (Serbia)
Authors: Filipovic Lazar , Tosic Ivana
Published: March 2024

Quantifying the intensity of a drought is not an easy task, as one has to take intoaccount multiple parameters, for example rainfall, temperature, soil water content, etc.Numerous indices have been developed to tackle this issue, and some of the most widelyused are standard precipitation index (SPI) and standard precipitation evapotranspiration index(SPEI), which, as the name implies, standardize precipitation and evapotranspiration over apoint for a certain time period and use that as a reference for an estimate of available water.The goal of this work is to analyze these drought indices for a long-term time period,take a look at their correlation and compare them with available records. The theoreticaldifference between the two indices is in the fact that SPEI takes (potential) evapotranspirationinto account, while SPI does not. Since sufficient measured evapotranspiration data was notavailable, potential evapotranspiration was used, calculated by the Thorntwaite method(taking into account temperature and geographical position). Precipitation and temperaturedata was acquired from the station network ran by the Republic Hydrometeorological Serviceof Serbia, for the time period of 1961-2020. Since the SPI and SPEI can be computed fordifferent timescales, in this study the indices for 3-, 6- and 12-months were compared.The results show that despite high correlation between SPI and SPEI (r > 0.9), theirbehavior in regards to drought events shows an important difference. This is visible in thetemporal spread of the dry months. SPEI depicts the last two decades as much drier than SPIdoes, and inversely, the sixties and the seventies as much wetter. Also, for the whole timeperiod, SPEI shows a trend towards more dry conditions, while SPI shows no clear trend.This is a consequence of rising potential evapotranspiration, which in itself is a consequenceof rising average temperatures.The conclusion is that the indices should not be used interchangeably and withtemperature data being as available as precipitation data, SPEI is more representative ofwater budget in the area in question.
4D synchrotron imaging of CO2 transport in reservoir rocks and caprocks: Informing safe CO2 sequestration    
Authors: Taylor Kevin , Wang Ke , Ma Lin
Published: March 2024

Tracking CO2 transport in subsurface rock during geological carbon sequestration has received significant attention. Although X-ray computed tomography (XCT) imaging techniques, visualization and quantification of CO2 behavior has been undertaken by previous researchers, little attention has been given to the nature of CO2 transport in a reservoir-caprock interface with well-developed pores in the reservoir and micro-fractures in the caprock. As the transition of two different pore systems, this complex system is crucial in controlling the sequestration safety case. We have used advanced time-lapse synchrotron imaging at in-situ pressure and temperature conditions to image the CO2 transport process in such an experimental system, for both gaseous and supercritical phases.Dynamic XCT images of fluids and the pore- and fracture-system in the mudstone and sandstone couplet were acquired at high resolution (effective voxel size 1.625 µm). Strain maps following high-speed gaseous and supercritical CO2 (ScCO2) flooding were modelled using a digital volume correlation (DVC) method to reveal the hydro-mechanical effects. The results suggest that under the influence of brine, high-speed gaseous CO2 will not increase the total pore-throat volume and can even cause a reduction in permeability in sandstone due to fines migration induced by CO2 flooding. Clay behavior, notably dispersion in brine, migration of fines and swelling induced by CO2, plays a notable role in the opening and closing of pores/fracture. Fluid breakthrough occurred at 10.6 MPa during high-speed ScCO2 injection. The significant fracturing effect of high-speed ScCO2 resulted in the connection of natural fractures in the mudstone with newly developed secondary branches and also created larger pore space in the sandstone, leading to an increase in porosity by approximately 2.8 times in the mudstone and 1.6 times in the sandstone. Additionally, there was an approximate increase of 2.6 times and 8.6 times in the permeability of mudstone and sandstone, respectively, after CO2 phase transition. The concentrated strains around the main fracture in the mudstone and web-like strains around the boundary of granular minerals in sandstone show the different modes of action of ScCO2 when passing through a reservoir rock and caprock system. This work is of practical significance in improving understanding of CO2-fluid-rock interaction in a complex reservoir-caprock system.
Utilizing convolutional neural networks for ground-based cloud observations
Authors: Rosenberger Markus , Dorninger Manfred , Weissmann Martin
Published: March 2024

Clouds of any kind play a substantial role in a wide variety of atmospheric processes, e.g. radiation, and moisture transport. Moreover, knowledge of currently occurring cloud types allows the observer to draw conclusions about the short-term evolution of the state of the atmosphere and hence also the weather. However, the number of operational cloud observations is rather decreasing than increasing due to high monetary and personnel expenses. To counteract this trend, we train a multi-input residual neural network architecture from scratch with ground based RGB images, where each instance consists of 4 images. Human cloud observations from nearby SYNOP station Vienna Hohe Warte are used as ground truth. To the best of our knowledge we are the first to classify clouds with this methodology into 30 different classes, which are consistent with the state-of-the-art scheme for operational cloud observations. Of these 30 classes up to three can be observed simultaneously in the same instance, making this a multi-input multi-label classification problem. Additional difficulty stems from highly imbalanced ground truth class distributions, with the most abundant cloud class being observed several hundred times more frequently than the least abundant class, leading to strong biases in the model output. To reduce these biases, class-specific resampling methods are used, which increase the total number of available instances from less than 12,000 to more than 20,000. This resampling is fundamental to get sufficient results.We conducted a large number of experiments covering a variety of model architectures, as well as different loss and class weighting functions. Preliminary results will be shown, which indicate very high precision and sufficiently high recall in most classes of the validation data, especially in those where aggressive resampling strategies have been used. The performance is even better, when classes with visual similarities are combined during validation. Thus, a substantial portion of false predictions can be explained by the model's confusion of similar-looking classes. Results also show that biases due to class imbalances are heavily reduced but are still present. Overall our classifier also shows exceptionally good reliability.With such a machine learning method and a common camera system, clouds can be observed independently and operationally where no human observations are available. This also allows a permanent monitoring of the current state of the weather as well as its short-time evolution. Apart from this, further applications of such an automated cloud classifier may be model verification, or cloud monitoring with high temporal resolution in the proximity of solar power plants. There, upcoming clouds can substantially change the possible energy output, which leads to the necessity of taking precautions. 
Recent enhancement and prolonged occurrence of MJO over the Indian Ocean and their impact on Indian summer monsoon rainfall
Authors: Sasikumar Keerthi , Nath Debashis , Wang Xu , Chen Wen , Yang Song
Published: March 2024

The Madden–Julian oscillation (MJO) is one of the leading modes of tropical intra-seasonal variability, which exerts significant impacts on the weather and climate across the globe, particularly in the tropics. MJO affects the Asian monsoon by producing enhanced and suppressed convection during the active and break periods, respectively. In the recent decades, the heat content of Indo-western Pacific Ocean has increased significantly, which strengthened the MJO activity. Previous studies also have shown that the expansion of Indo-western Pacific warm pool led to the warping of MJO life cycle, which decreases its residence time over the Indian Ocean (IO) and increases over the Pacific Ocean. Here we show that in the boreal summer months, MJO amplitude has strengthened during the global warming hiatus or rapid IO warming period (1999–2015) compared to the previous period (1982–1998). In the later period, MJO exhibits a faster regeneration over the western IO, and its residence time has increased in the western hemisphere and western IO but decreased in the eastern IO and eastern Pacific Ocean. The strengthening of MJO and the readjustment in its residence time are due to the local MJO feedback on the IO and the La Nina like sea surface temperature pattern in the Pacific Ocean. The prolonged MJO activity leads to bursts of rainfall over the Indian subcontinent in Phase 3 and Phase 4, influencing the active spells of the Indian summer monsoon and causing heavy rainfall over central India and East Asia.