bluuebunny/crossref_metadata_2025 huggingface dataset:
Oscillatory Melancholia state of the Atlantic Meridional Overturning Circulation in an intermediate-complexity climate model
Authors: Börner Reyk , Mehling Oliver , von Hardenberg Jost , Lucarini Valerio
Published: March 2024

The Atlantic Meridional Overturning Circulation (AMOC) is considered a tipping element of the earth system featuring bistability: for a given external forcing, a strong and a weak circulation state coexist as competing attracting states of the system. In the presence of random fluctuations, noise-induced transitions between the competing states are possible, posing a risk of abrupt AMOC tipping even without crossing a critical forcing threshold. It is thus crucial to better understand the stability landscape of the earth system with a multistable AMOC, particularly the properties of the boundary separating the basins of attraction of the strong and weak AMOC states. For weak noise, transitions are expected to cross the basin boundary at so-called edge states or "Melancholia states", typically chaotic saddles which are attracting on the boundary but asymptotically unstable. Here we find an edge state between the two stable AMOC states in an earth system model of intermediate complexity, PlaSim-LSG. Our approach is based on an edge-tracking technique that allows to construct a pseudo-trajectory on the chaotic saddle. We characterize the climatic and dynamical properties of this edge state and map out its location in different projections of state space. Near the edge state, the AMOC strength exhibits strong transient oscillations which we link to the ongoing physical processes. We relate our findings to the theory of unstable chaotic sets and discuss implications for the predictability of potential AMOC tipping in the future.
Characterisation of drainage dynamics of karst landscapes over Europe
Authors: Olarinoye Tunde , Weber Nane , Gleeson Tom , Marx Vera , Liu Yan , Hartmann Andreas
Published: March 2024

Karst aquifers play a crucial role as water sources globally, with several European countries relying significantly on them for their water supply. Managing these aquifers is challenging due to their subsurface hydraulic heterogeneity. Hydrological modeling has proven valuable, offering insights into the hydraulic dynamics and management of karst water resources. However, characterizing karst drainage attributes at large catchment and regional scales remains challenging, hindering the incorporation of spatial heterogeneity and complexity in large-scale models and leading to unrealistic estimations in karst regions. This study addresses the issue by providing the first regional estimation of karst drainage attribute across Europe, this attribute is herein called Karstification Index (KI). Leveraging a newly developed automated karst spring recession analysis tool, and extensive climatic and physiographic datasets, we applied a regression-based regionalization model to estimate slow and quick flow parameters in karstic landscapes. By estimating KI as the ratio of quick to slow flow parameters, we were able to identify sub-regions with higher and lower degrees of karstification. Our findings highlight the significance of drainage density metrics, particularly in combination with specific climate signals, as predictors of KI. The regionalization model demonstrated high performance, validated by high R2 values, especially in well-gauged European catchments. Encouraged by these results, the analysis is being extended to a global scale, marking the first attempt to estimate karstic drainage attributes globally. We believe that this large-scale parameterization of karstification will enhance regional and global karst water resource management. By improving the parameterization and consideration of karst processes in large-scale hydrological models, our research contributes to a more accurate understanding of karst aquifers on a global scale.
East Antarctic Ice Sheet response to ocean forcing during the Middle Miocene Climate Transition: Insights from Prydz Bay
Authors: Evangelinos Dimitris , van de Flierdt Tina , Paredes Eduardo , D. Pena Leopoldo , Cacho Isabel
Published: March 2024

Understanding ocean-ice sheet interactions in the geological past is critical for evaluating the ice sheet sensitivity to ocean forcing in future climate warming. Geological evidence suggests major oceanographic changes across the Southern Ocean during the Middle Miocene Climate Transition (MMCT) (~15-12 Million years ago (Ma)). However, the response of the East Antarctic Ice Sheet to these changes remains poorly constrained. Here we explore ocean-ice interactions during the MMCT by presenting data from two marine sedimentary cores along a latitudinal transect offshore Prydz Bay (East Antarctica). Ocean Drilling Program (ODP) Site 1165 is located on the continental rise off Prydz Bay (64◦27.27o S, 67◦13.08o E, 3537.5 water depth) and ODP Site 744 is located on the Southern Kerguelen Plateau (61o 34.66´S, 80o 35.43´E, 2307 m water depth). Neodymium and strontium isotopic compositions of fine-grained (< 63μm) detrital sediments from ODP Site 1165 were generated to constrain potential changes in sediment provenance, revealing potential changes in ice sheet dynamics (expansion/retreat). Neodymium isotope ratios (εNd) from fossil fish teeth from ODP Site 744 were used to trace regional water masses and Southern Ocean circulation changes for the same period. Additionally, marine productivity records generated from both ODP sites were used to track changes on the position of the Southern Ocean frontal system. We report an equatorward migration of the Southern Ocean frontal system around 13 Ma, associated with global climate cooling, sea ice expansion and CO2 decline during the MMCT. Despite this major ocean-climate reorganization, our data suggest the presence of a rather stable and large ice sheet in the Prydz Bay throughout the MMCT, implying that the ice sheet was less sensitive to ocean forcing during the MMCT.
Passive seismic survey across the fault-zone of Introdacqua, central Italy: the subsurface geological structure role on the site amplification pattern 
Authors: Pischiutta Marta , Mercuri Alessia , Fina Federico , Salvini Francesco , Minarelli Luca , Cultrera Giovanna , Di Giulio Giuseppe
Published: March 2024

In this work we perform a detailed passive seismic survey in proximity of a shear zone in the Introdacqua area, central Italy, around the permanent seismic station IV.INTR of the Italian seismic network RSN. This station is located on a prominent ridge (width of about 200 m, relative height of about 240 m), and is affected by a clear directional amplification between 1 and 3 Hz, with maximum amplification along N160° azimuth, as shown by HVSRs calculated using both seismic events and ambient noise recordings (CRISP database, www.crisp.ingv.it). This effect was confirmed by 11 ambient noise measurements performed nearby station IV.INTR in the framework of an agreement with the Italian Civil Protection. Since the maximum amplification occurs parallel to the topography elongation, it is not explainable through the topo-resonant model (e.g. Géli et al. 1988).In this work, to better investigate the anomalous seismic response, as well as the areal extension of the directional effect, we implement an array of further 32 ambient noise measurement points, including a larger area around the topography. We find that the directional effect along N160° azimuth is gathered only at measurement sites close to IV.INTR, disappearing when increasing distances (over 300 m). A detailed structural geological survey suggests the presence of intensely fractured rocks produced by a fault located close to station IV.INTR, fractures strike being concentrated around N70°-80° azimuth, transversally to the directional effect. This is in agreement with several literature papers suggesting that across fault zones directional amplification is transversal to the prevailing fracture strike (e.g. Pischiutta et al., 2023, and references therein).The Introdacqua study case suggests that anomalous amplification patterns can be found on topography as an effect of the subsurface geological structure, rather than being produced by the sole convex shape. Since topographic irregularities and rock fractures often coexist in tectonically active zones, this is a key point to interpret amplification at sites with pronounced topography. For this reason, Introdacqua was chosen as a test-site in the of the ongoing INGV-GEMME international project, whose aim is the study of the seismic site response in complex 3D geological and morphological settings, and the deep investigation of the wave propagation by using 3D numerical modeling, to provide guidelines for future site characterization.
Flexural Pumping and the Origins of Petit-Spot Volcanism
Authors: Vannucchi Paola , Shi Yanan , Yang Ting , Fujie Gou , Morgan Jason P.
Published: March 2024

Most volcanic activity on Earth is linked to well-known processes like plate tectonics and mantle plumes, typically through mechanisms such as flux-melting in subduction zones and decompression-melting at ridges and mantle plumes. However, recent discoveries point to a different origin for some intraplate volcanism, a key example being 'Petit-Spots'—small volcanic mounds that erupt on incoming plates near subduction zones. Here we propose that flexural pumping, occurring as the subducting slab unbends, transports fluids released by intra-slab dehydration to the slab's base where these fluids induce flux-melting in the warm slab base and asthenosphere beneath the slab. Counterflow in the buoyant asthenosphere beneath the subducting plate further expands the region of petit-spot volcanism. This mechanism not only explains the origin of petit-spot volcanism but also suggests a broader conceptual model for generating low-degree melts in the oceanic asthenosphere.
Wappfruit, a project for the optimization of the irrigation in agriculture: final results
Authors: Canone Davide , Gisolo Davide , Nari Luca , Pettiti Francesca , Gentile Alessio , Ferraris Stefano , Barezzi Mattia , Garlando Umberto , Demarchi Danilo
Published: March 2024

The Wappfruit project objective is to optimize the irrigation techniques for water and energy saving in fruit orchards in the Piemonte Region, Northwest Italy. The stakeholders of the project are Politecnico and the University of Torino, Piemonte Region, Agrion Foundation for Research in Agriculture, Astel S.r.l. (for the industrialisation of the experimental hardware developed by Politecnico di Torino), and three farms (“La Marchisa” and “Lorenzo Sacchetto” – apple orchards and “Paolo Vassallo” – actinidia orchard).  In each farm, two areas were identified, an “experimental area” where the new set-up was tested and a control area where the farmers continued the irrigation as usual.In the year 2023, the Wappfruit project has shown the potentiality of a smart irrigation solution composed of two kinds of IoT (Internet of Things) nodes employing LoRa technology and governed by a 24/7 server script, written in Python, that acquires soil matric potential and decides the opening and closure of the irrigation pumps in real-time. The soil matric potential thresholds, identified in 2022 and early 2023, (-60 kPa and -25 kPa at 20 cm of depth for the activation of the irrigation, respectively in the apple and Actinidia orchards; -50 kPa at 40 and 20 cm of depth and -18 kPa at 20 cm of depth, for the deactivation of the irrigation, again respectively for apple and Actinidia orchards) were verified again after a campaign in which soil parameters (saturated soil water content, infiltration velocity at saturation) were measured. These values were used for new model simulations that included irrigation. The thresholds for the apple orchards were confirmed, whereas new thresholds were identified for the Actinidia: -12 kPa (activation) and -5 kPa (deactivation). Results highlight that these thresholds can activate and deactivate the irrigation appropriately. The 2022 simulations show a matric potential in agreement with the measures collected (R between 0.51 and 0.88). Moreover, the 2023 simulations with modelled irrigation show a good agreement with the measures in the experimental area. Both the simulations and the real optimized irrigation generally show lower values if compared with the irrigation of the farmers (range: 13 – 217.5 mm/ha), with an exception in one apple orchard, where the model suggests more irrigation than expected, likely because of an overestimation of the water infiltration velocity. The hardware/software design and implementation have shown that low-cost low-power electronic devices and artificial intelligence can be reliable and very inexpensive for water and energy savings. The remote control of the system is another important achievement. Moreover, optimized irrigation does not affect the vegetation productivity and increases the fruit quality.
Sorption of Persistent, Mobile, and Toxic (PMT) and very persistent, very mobile (vPvM) substances onto pyrogenic carbonaceous materials
Authors: Xu Jiaqi , Cama Jordi , Teixido Marc
Published: March 2024

Chemical pollution is recognized as a global problem, arising from trace organic contaminants (TOrCs), such as the emerging persistent mobile, and toxic (PMT) and very persistent, very mobile (vPvM) organic compounds. Rapid urbanization has increased impervious surfaces, facilitating the deposition and accumulation of pollutants. Additionally, stormwater acts as a transportation conduit for this PMT/vPvM substances, functioning as a surface pollutant wash-off, discharges into water bodies, and decreases the urban water quality. Green infrastructure, mainly designed to mitigate flood risk and recharge aquifers, may contaminate the soil-groundwater system. It is therefore crucial to develop cost-effective remediation technologies to enhance the removal of polar contaminants before reaching the aquifer.In this study, a laboratory-based removal evaluation for 20 cost-effective PCMs (e.g., activated carbons and standard biochars) towards 34 PMT/vPvM target compounds (covering a wide range of uses, e.g., biocides, additives, herbicides) has been conducted. Preliminary results show that activated carbon (GAC), regenerated activated carbon (RAC) and MSP700 biochar exhibit strong adsorption capabilities for PMT compounds. The pyrolysis temperature, surface area, and aromaticity of the PCM play a crucial role in the adsorption process. The sorption kinetics for a suite of eight representative PMT compounds (covering a broad range of physicochemical properties) is better reproduced using a pseudo-second order (PSO) model, indicating a diffusion-controlled process. Sorption equilibrium for most adsorbates is achieved within 48 h. GAC, with the highest specific surface area, exhibits rapid adsorption, whereas MSP700 biochar shows the slowest adsorption rates. Furthermore, the sequence of adsorption capacity for the studied adsorbates is: neutral > positive > negative. Finally, the identification of GAC, RAC, and MSP700 as effective adsorbents for PMT/vPvM substances offers valuable insights for next-generation urban water management.
Inferring North Atlantic Deep Water Transports from Ocean Bottom Pressure at the Western Boundary
Authors: Thomas Maik , Shihora Linus , Dobslaw Henryk
Published: March 2024

Estimating oceanic transports of volume, heat, carbon, and freshwater is fundamental to understanding the ocean’s role in the evolving climate system. Unique in this context is the Atlantic Meridional Overturning Circulation (AMOC) that comprises a net northward transport of relatively warm water at depths of ≲1 km throughout the Atlantic basin, compensated at ≳1–5 km by a colder net southward return flow.While in-situ measurements, such as the RAPID array at 26.5°N, are considered the 'gold standard' to monitore changes in the AMOC, measurements at many latitudes and the detection of e.g. basin-wide modes are non feasible.However, variations in the overturning are to a good degree accompanied by associated changes in oceanic bottom pressure which opens up new avenues of AMOC monitoring through bottom pressure recorders or even through future satellite gravimetry measurements. Here, we investigate the connection between changes in the Atlantic overturning and associated variations in bottom pressure along the western continental shelf in a suite of ocean models. This includes high resolution simulations from a CMIP6 FESOM run by AWI, the regional VIKING20X model by GEOMAR. We investigate to what degree the transport variations can be inferred from bottom pressure signatures alone, limitations of the approach and especially how such signatures could be implemented into a future iteration of the ESA ESM. This would allow the inclusion the these transport-related OBP changes in dedicated simulation studies for future satellite gravimetry missions.
Methodologies for climate tipping points analysis and risk assessments in TIPMIP
Authors: Donges Jonathan F. , Dennis Donovan P. , Loriani Sina , Sakschewski Boris , Wunderling Nico , Winkelmann Ricarda
Published: March 2024

The Tipping Point Modelling Intercomparison Project (TIPMIP) is an international initiative that aims to systematically improve our understanding of potential tipping dynamics in different components of the Earth system and to assess the associated uncertainties (www.tipmip.org). By linking and evaluating different models through a systematic framework, TIPMIP aims to fill critical knowledge gaps in Earth system and climate risks by improving their assessment at different levels of anthropogenic forcing and associated long-term commitments and irreversibilities. The Methods and Risk Assessment Working Group of TIPMIP will further develop the methodological foundations of this systematic approach to the study of tipping dynamics in domain-specific and coupled Earth system  numerical models to support future assessment reports and comprehensive risk analyses. In this contribution, we introduce the Methods and Risk Assessment Working Group within TIPMIP, and highlight relevant lines of methodological development to be pursued, including: (i) systematic and automated detection of tipping points and critical transitions in model output and Earth observation data for TIPMIP (e.g, the TOAD framework), (ii) detection of non-linear regime shifts in time series data for TIPMIP beyond amplitude shifts, e.g. transitions between more regular and more erratic variability (e.g. the pyunicorn toolkit), and (iii) probabilistic analysis and emulator approaches of risks for triggering tipping events and cascading tipping dynamics at different levels of anthropogenic forcing (e.g. the pycascades approach).
Linking synoptic flow and city dynamics: PANAME observations of the Paris urban boundary layer  
Authors: Kotthaus Simone , Haeffelin Martial , Céspedes Jonnathan , Ribaud Jean-François , Dupont Jean-Charles , Drouin Marc-Antoine , Martinet Pauline , Lemonsu Aude
Published: March 2024

Atmospheric boundary layer dynamics form in response to synoptic flow and surface-atmosphere exchanges. Over cities, the complex roughness and additional heat from storage and anthropogenic emissions clearly affect atmospheric stability, with implications for heat risk and pollution dispersion. This work examines how the specific dynamics of the Paris region urban atmosphere interact with the synoptic flow using observations from a dense measurement network.The interdisciplinary PANAME initiative is a framework coordinating the synergy of numerous projects that are studying the Paris atmosphere using both numerical modelling at various scales and novel observations. The measurement network not only includes dense surface station measurements and turbulent flux towers, but also ground-based atmospheric profile remote sensing and additional radiosonde measurements within the city. This work exploits observations from automatic lidars and ceilometers (ALC), Doppler wind lidars (DWL), and microwave radiometers (MWR) that are operated along a suburban-urban transect to collect simultaneous profiles of air temperature, wind, turbulence, and aerosol characteristics at high vertical and temporal resolution. The continuous observations from a network of compact ground-based remote sensing instruments are shown to be extremely valuable for an improved understanding of the complex processes that govern the urban atmosphere as they are highly variable in space and time.The complex dynamics of the urban atmospheric boundary layer are explored through advanced measurement products, such as low-level jet characteristics and mixed layer heights. We evaluate how different indicators of atmospheric stability from synergy of multiple remote sensing profile data can portray the spatial and temporal variations in urban boundary layer dynamics. The work highlights the importance of atmospheric boundary layer dynamics as a crucial driver for near-surface conditions.
OGC Web APIs to Make Data Available in the Green Deal Data Space
Authors: Masó Joan , Brobia Alba , Zamzov Malte , Serral Ivette , Hodson Thomas , Palma Raul , Bastin Lucy , Lush Victoria
Published: March 2024

The Green Deal Data Space is born in the big data paradigm where sensors produce constant streams of Earth observation data (remote sensing or in-situ). The traditional and manual organization of data in layers is no longer efficient as data is constantly evolving and mixed together in new ways. There is a need for a new organization of the data that favors users and in particular can be considered ready for use. The AD4GD project proposes a threefold solution: A new information model, dynamic multidimensional datacubes and OGC APIs for data query and filtering. The use of data in the context of the Green Deal is difficult due to the wide heterogeneity of data sources (many times expressed in different data models) and different semantics used to represent data, and the lack of sufficient interoperability mechanisms that enable the connection of existing data models. The solution is a framework composed by a suite of ontologies implemented in line with best practices, reusing existing standards and well-scoped models as much as possible and establishing alignments between them to enable their interoperability and the integration of existing data. This approach was successfully applied to object based data stored in a RDF triple store e.g. vector data and sensor data) in the agricultural sector. The traditional representation of static two-dimensional layers needs to be replaced by a dynamic view where time becomes an extra dimension. In addition, other dimensions emerge such as the height in atmospheric and oceanic models, the frequency in hyperspectral remote sensing data or the species in a biodiversity distribution model. These dimensions define a data cube that offers an entry to a constantly evolving world. The dimensions in the datacube as well as the values stored in the cube cells (a.k.a. attributes) should be connected to the concepts in the Information Model. In the big data paradigm access to individual layers is difficult due to the dynamic nature of the data. Instead we need a set of modern APIs as an entry point to the data in the data space. The OGC APIs offer a set of building blocks that can be combined together with other web API design principles to build the Green Deal Data Space data access APIs. Users will be able to get the necessary data for modeling and simulating the reality using the OGC APIs endpoints described in the OpenAPI description document. The OGC APIs include the concept of collections as an initial filtering mechanism but a filtering extension using CQL2 is in advanced draft status. It is fundamental that the OGC APIs are also capable of generating detailed metadata about the extracted subset including data sources, producer information and data quality estimations.AD4GD is a Horizon Europe project co-funded by the European Union, Switzerland and the United Kingdom.
Estimating Pleistocene ice thickness from pillow lava melt inclusions in the south-central highland of Iceland
Authors: Collins Harrison , Bali Eniko , Gudmundsson Magnus T.
Published: March 2024

Paleoclimate records show that Iceland was at times fully covered during Pleistocene glaciations. Models and data for the last glacial maximum indicate that the ice sheet at this time extended several tens of kilometers beyond the present coast. In contrast, much is known about the extent of the ice sheet during other times of the Weichselian glaciation, and very little information exists on possible variations of earlier glaciations. The regions near Þórisvatn, Jökulheimar, and Bláfjöll in the south-central highland of Iceland contain many outcrops of Pleistocene pillow lavas. The volatile contents in the glassy rims of pillow lavas may record the ambient pressure during eruption. This could offer insight into syn-eruptive glacier thickness. 15 samples were collected from three sample locations near Þórisvatn, one near Jökulheimar, and four near Bláfjöll from August 14 to August 15, 2023. Samples were crushed and sieved into 0.5-2.0 mm grains, and the glassiest grains were double polished with thicknesses between 88–219 µm for FTIR analysis. The spectra showed strong similarity to FTIR spectra of Holuhraun samples of similar thickness. H2O contents of the samples varied between 0.22–0.32 wt%, with a median of 0.30 wt%. CO2 was under the detection limit of the FTIR analyses. This may be an artifact of polishing grains too thin, and thus separate analyses with thicker grains will be carried out to accurately assess ambient pressure due to pressure model sensitivity to CO2. Further analysis will include S concentrations, which will be used alongside H2O and CO2 to calculate a precise ambient pressure with the Sulfur_X model (Ding et al., 2023). The derived parameters will be used to estimate glacier thickness.
Exploring the impact of the vertical grid spacing for the climate simulated in a global storm-resolving model
Authors: Schmidt Hauke
Published: March 2024

In recent years, great efforts have been made to reduce the horizontal grid spacing of atmospheric models to a few kilometers to build so-called Global Storm-Resolving Models (GSRMs). However, the vertical grid spacings used in these models are generally of the same order of magnitude as those used in classical climate models with horizontal grid spacings of a few hundred kilometers. From previous sensitivity experiments with a variety of model types, from direct numerical simulations to these classical climate models, it is known that especially the simulation of clouds can strongly depend on the vertical model resolution. To test the importance of the vertical grid spacing in GSRMs we have performed simulations with the ICON atmospheric model at 5 km horizontal grid spacing and with between 55 and 540 vertical layers, corresponding to maximum tropospheric vertical grid spacings between 800 and 50 m.  Here we present results of these simulations. They results show that for most of the variables considered, halving the vertical grid spacing by half has a less pronounced impact than halving the horizontal grid spacing, but the effect is not negligible. For example, for each halving of the vertical grid spacing, coupled with necessary reductions in the time step length, cloud liquid water increases globally by approximately 7%, while it decreases by roughly 16% when halving the horizontal grid spacing. Both the grid spacing and the time step contribute to these effects. Comparison of selected climate variables with observations shows that model biases are only in some cases reduced by higher vertical resolution, because of the dominance of model biases with other origins.
Relative contributions to suspended sediment variability under extreme events (Gironde Estuary, France)
Authors: Tavora Juliana , El Hourany Roy , Fernandes Elisa , Sotollichio Aldo , Salama Suhyb , van der Wal Daphne
Published: March 2024

The frequency and intensity of extreme events associated with climate change are projected to increase continuously in the coming decades. Within these scenarios, the effects and ramifications of extreme events on coastal ecosystems are still poorly understood. In particular, the spatiotemporal footprint of extreme events is required to devise a strategy for better mitigation of impacts. Satellite data provide a unique spatial capability to address the effects of extreme events, for example, on Suspended Particulate Matter (SPM) in coastal waters. However, the low temporal resolution (e.g., associated with cloud disturbances) leads to small or insufficient samples to capture the dynamics of a given coastal system. On the other hand, although hydrodynamic sediment transport models provide continuous spatial-temporal estimates of SPM, refining their realistic flow of SPM importation or accurate sediment class distribution, especially capturing extreme events, remains challenging.The new generation of statistical approaches comprising machine learning techniques is a valuable tool for comprehensive cube data time series of satellite remote sensing data with spatial and temporal gaps. Here, we propose a machine learning framework.  The framework allows not only filling spatial gaps in satellite imagery (compromised due to cloud disturbances) but also the estimation of the spatial estuarine domain affected by extreme events in river discharge and windbursts. Preliminary results also suggest that SPM dynamics is largely influenced by hydrodynamic forcings (river discharge, tides, winds), but depth can also play a significant role. Our study demonstrates that machine learning might be useful to synthesize coherent spatial and temporal distribution patterns of SPM variability, highlighting where extreme events most and least likely affect the estuarine system. The latter provides valuable insights for coastal management, such as prioritizing regions mosltly influence by extreme events for ecological monitoring and maintenance of critical habitats.
Investigation of combined regional trends of extreme precipitation and temperature in southern Italy
Authors: Nikravesh Gholamreza , Senatore Alfonso , Mendicino Giuseppe
Published: March 2024

This contribution proposes an integrated analysis of climate regime trends in southern Italy (Calabria Region), focusing on both extreme precipitation and temperature events. Provided several precipitation and temperature observations available in the period 1955-2023 for a relatively dense monitoring network (approximately a rain gauge station per 110 km2 and a temperature station per 100 km2), four precipitation-related variables like total precipitation (PRCPTOT), maximum one-day precipitation (RX1day), maximum five-day precipitation (RX5day) and Consecutive Dry Days (CDD) were chosen. Also, three temperature-based variables were selected, i.e., the maximum of the maximum daily temperatures (TXx), the mean of the mean daily temperatures (Tmean), and the minimum of the minimum daily temperatures (TNn). The trends of these seven selected variables were assessed and combined through three approaches at the annual and seasonal scales, considering each available monitoring station (namely, 134 precipitation and 148 temperature stations). First, we combined PRCPTOT and RX1day to highlight which stations have an increased probability of both drought and flood risks, developing a novel integrated climate regime index (ICRI). Then, we considered the three temperature indices, TXx, Tmean, and TNn, to pinpoint stations that have experienced more robust rising trends. The third analysis combined PRCPTOT, RX1day and temperature (using alternatively TXx, TNn and Tmean) to investigate the compound risk of flood, drought and, to a certain extent, wildfires. The results indicate a rather homogeneous increase of all temperature-related variables, especially starting from 1990, and that since 1955, a considerable number of stations have experienced increasing trends for RX1day and falling trends for PRCTOT. Therefore, most of the territory of the region is more likely to confront water stress, flood and forest fires.
Do temporal changes in soil density affect cosmic ray neutron sensing: a multi-site comparison
Authors: Scheiffele Lena M. , Dimitrova Petrova Katya , Schrön Martin , Nieberding Felix , Bogena Heye R. , Verrot Lucille , García Quiroz María O. , Geris Josie
Published: March 2024

Cosmic ray neutron sensor (CRNS) technology is increasingly promoted in agricultural environments for monitoring of volumetric soil water content (SWC). Among its advantages over traditional measurements is the provision of field-scale representative SWC timeseries without obstruction of management activities. To derive an integrated SWC average at a site, CRNS is typically calibrated using observations of gravimetric SWC, soil organic matter and bulk density (BD). Those variables may in the best case be derived from a large number of soil samples, collected ideally on multiple occasions and under a range of hydrometeorological conditions. Most CRNS applications use an average site-specific value of bulk density derived for a site from ≥1 field calibration and it is considered static over time. While this is a safe assumption for many environments, in agricultural settings, management activities (e.g. tillage) may introduce substantial changes in BD over time. This may affect the accuracy of the CRNS-based SWC estimates, which in turn could affect management decisions (e.g. on irrigation) or modelling efforts, relying on the CRNS estimates as inputs.Therefore, the objective of this work is to quantify the relevance and potential impact of temporal changes in BD both on the estimation of CRNS SWC (e.g. of interest for land managers) and on the neutron count rate. We focused on agricultural environments where temporal changes in BD are deemed relevant. For that we used data from four agricultural sites (three in Germany and one in Scotland, UK) spanning different soil types, level of agricultural management and hydrometeorological conditions. The selected sites are equipped with a stationary CRNS and BD was sampled on 3 or more occasions for sensor calibration. We quantify the differences in estimates of SWC by using the range of average BD values at a site and compare these differences to other sources of uncertainty (e.g. the integration time of neutron counts). We additionally consider existing theories on the interaction of neutrons and soil bulk density to evaluate the direct impact of BD changes on the neutron count rate with dedicated simulations. Finally, we make recommendations on when BD variability and thus its sampling over time may become important for the derivation of CRNS outputs.
Frictional Response of Clay-rich Sandstone to Pore-Pressure Oscillation Throughout Interseismic Periods
Authors: Bigaroni Nico , Mecklenburgh Julian , Rutter Ernest
Published: March 2024

During interseismic periods a fault at depth can experience non-constant effective normal stress due to fluctuations in the pore-fluid pressure. Pore-pressure oscillations may influence the healing capability of the fault and ultimately affect its reactivation. Thus, studying the behaviour of faults during interseismic periods is a critical factor in understanding the seismicity. Triaxial tests were conducted using saw-cut (45o) samples of Pennant Sandstone to investigate the influence of pore-pressure oscillations during slide-hold-slide (SHS) tests (th = 900 – 7300s) on its frictional behaviour and fault reactivation. The cylindrical samples were hydrostatically compacted at 30 MPa and pore-pressurized with argon gas at 5, 10 and 18 MPa resulting in effective normal stress (σ’n) 25, 20 and 12 MPa, respectively. Then the saples were deformed at a constant shear displacement rate ≈ 4.5 μm/s. To overcome the displacement hardening tendency of the sample geometry, we servo-controlled the confining pressure so that the resolved normal stress on the sliding surface is kept constant. Experimental observations revealed a significant influence of pore-pressure oscillation on the frictional behaviour resulting in an increase in both frictional healing and creep relaxation. Moreover, this effect was enhanced as the effective normal stress was increased further. To understand better the underling mechanism(s) that influences these time-dependent processes we coupled the frictional results with permeability measured using the oscillating pore pressure method during the SHS tests. Finally, we tested how the pore-pressure oscillation affected the fault reactivation by conducting creep experiments at constant shear stress while the fault was brought to reactivation via progressive increase in fluid pressure. Our results demonstrated how non-constant effective normal stress history during interseismic periods deeply affects the fault behaviour, with important implications for natural and human-induced seismicity.
Ammonia emission measurements from agricultural and industrial structures using an inverse dispersion method accounting for deposition loss
Authors: Valach Alex , Häni Christoph , Bühler Marcel , Mohn Joachim , Schrade Sabine , Kupper Thomas
Published: March 2024

Ammonia emissions produce negative environmental and human health impacts with largest emissions originating from agriculture. Especially in countries with high livestock density, the majority originate from animal housing and application to fields. Measuring total emissions from multiple heterogenous source structures such as farms and waste treatment facilities can be challenging due to losses from transport, deposition, and chemical transformation. Previous studies have shown that quantifying net fluxes at this scale can be achieved by combining concentration measurements up- and downwind of the structures with inverse dispersion modelling to calculate the emissions from a defined source area. However, this method underestimates total emissions, as it does not account for deposition loss, which must be modelled and can introduce large uncertainties (
Assessment of Compound Drought and Hot Extreme Conditions Over West Rajasthan, India
Authors: Gaur Nishant , Chavan Sagar , Singh Amit
Published: March 2024

Compound extremes characterized by simultaneous or consecutive incidence of multipleextreme events (i.e. dry and hot extremes), or fusion of extreme events amplifying theirindividual impacts, or amalgamation of non-extreme events resulting in an extreme impactwhen combined. Our key focus was on understanding compound extremes, particularly theinteraction between prolonged dry spells and intense heat waves. We explored the individualextremes of drought (dry extreme) and high temperatures (hot extreme) using some essentialindices like SPI, STI, WSDI and CDD. Also to better understand these complex events, weemployed two specialized tool, the Compound Drought and Hot Extreme Index (CDHI) andone of the Joint extreme index (JEI) i.e. WDS (Warm and Dry Spell) for meteorologicalsubdivision-17 i.e. west Rajasthan region. Both CDHI and JEIs are used to characterize thejoint occurrence of extreme precipitation and temperature. In this study, we employedtemperature data from the Indian Meteorological Department (IMD), recorded at a resolutionof 1 degree, covering the years 1951 to 2019. Additionally, we gathered monthlyprecipitation data, which was observed at a finer resolution of 0.25 degrees, spanning from1901 to 2019. Moreover, to seamlessly integrate and refine our analyses, we applied 2Dbilinear interpolation, using Euclidean interpolation principles, to align the 0.25-degreegridded precipitation data with the 1-degree gridded framework of temperature. For instance,the SPI values of -1.77 and -2.28 for the monsoon seasons of 1987 and 2002, respectively,suggests that the meteorological drought in 1987 was less severe than in 2002. Conversely,the STI values indicate that 1987 was hotter than 2002, with STI values of 3.15 and 1.91,respectively. Consequently, comparing Compound dry and hot extremes based solely on SPIand STI data proves challenging. Therefore, CDHI served as a valuable metric for comparingthe overall severity of compound drought and hot extremes. A lower CDHI value indicatesmore severe compound drought and hot extremes, and vice versa. The CDHI values for theyears 1987 and 2002 were -2.91 and -2.51, respectively, suggesting severe compound droughtand hot extremes in 1987. Also, as we plotted the time series plot for the meteorologicalsubdivision 17, i.e., west Rajasthan region, it was observed that when the time periods weretiny (1, 3, or 6 months), the SPI, STI, and CDHI frequently moves above or below zero. Butas the time periods were lengthened or increased (12, 24, 36, or 48 months), the SPI, STI, andCDHI responded dilatorily to changes in precipitation, i.e., overall periods with positive andnegative values of indices reduced, but the ones which appeared were longer in duration.
Towards hurricane impact forecasting for the Dutch Caribbean  
Authors: Bloemendaal Nadia , Sluijter Rob , Diepeveen Jos , Koks Elco
Published: March 2024

The Royal Netherlands Meteorological Institute (KNMI) has been responsible for weather forecasting in the Dutch Caribbean (Bonaire, St. Eustatius and Saba – the BES islands) since 2016. And while weather patterns in the Caribbean often exhibit homogeneous characteristics, this region is also prone to some of the most violent storms on earth in the form of hurricanes. The most infamous example of this is Hurricane Irma (2017), which passed close to Saba and St. Eustatius but made a direct landfall on and severely impacted several other Caribbean islands, including Sint Maarten. Over 90% of the buildings on St. Maarten were damaged, including most of the infrastructure on the island. The estimated damage totaled to be around 2.7 billion USD (approximately 200% of the country's GDP).  

With its extensive weather forecasting expertise as a solid foundation, KNMI is now moving towards impact-based forecasting through the development of the Early Warning Centre (EWC). For the BES islands, this means that we will design a hurricane impact model, combining KNMI's forecasting experience with impact modeling expertise nested within academia. With respect to the latter, we follow the traditional risk modeling approach and set up a hazard – exposure – vulnerability type of model chain. In such model chain, it is predominantly the choice of hazard data that determines the nature and applicability of the output data. For instance, (ensemble) forecast tracks provide insights into possible impacts of an imminent hurricane. Similarly, using synthetic hurricane tracks from a statistical model like STORM will result in a full spectrum of risk and associated probabilities. We will also incorporate local knowledge to develop and improve exposure and vulnerability input data. 

In this presentation, we discuss the different input datasets needed to build an impact model, and how the different output products can assist weather forecasters in better understanding the impact of imminent hurricanes in the Dutch Caribbean.
Can Virtual Field Trips be used to prepare students for real fieldwork?
Authors: van Bever Donker Jan , Marshal Delia , Maart Rudy , Mayekiso Luyanda , Solomon Henok , Huber Matthew , Mgabisa Nompumelelo
Published: March 2024

As a result of significantly increased class sizes, heightened safety consciousness, significantly increased health and safety regulations, and limited staff resources, a project was started in 2017 to investigate ways and means to improve the impact of field instruction to undergraduate students.This allowed us to hit the ground running when COVID-19 hit the world, as the lock down regulations triggered a switch to teaching remotely. This significantly accelerated the development of our Virtual Field Trips (VFTs), in this case to be able to provide suitable field evidence for the students as group travel to the field was not possible, except the fourth year small groups.VFT’s were therefore developed for use at first year, second year, third year and fourth year level of instruction.  In close collaboration with the instructor responsible for teaching the various courses, three different sets of VFTs were developed:A set of four VFTs for the first year introductory Earth Sciences course, illustrating sedimentary, structural, and igneous features in outcrops as well as hand specimen. Three VFTs were used during practical teaching sessions followed by a test, after which the VFTs were available on-line for self-study. This was followed by the fourth, more comprehensive tour, which was used as an end of practical course test. Comparison of the two test results demonstrated a significant learning gain.One multi outcrop tour was prepared to illustrate the features the field geologist needs to look out for when applying structural geology to slope stability assessment in an engineering geological setting in the context of raising an existing storage dam wall to increase the storage lake capacity. This lecture was followed by a test prior to the VFT after which the same test was applied sfter the VFT. Comparing the results of the two tests demonstrated that the learning gain increased significantly in accordance with the level of education of the participants.Finally, a set of seven tours was built to prepare the fourth-year students prior to going to the field by showing them the various sedimentary features they were to visit in the field. Here we used video explanations on the outcrop, 3D LIDAR specimen and drone videos for the spatial aspect.  In this case the final report prepared by the students after the field excursion was compared with the results of the previous year’s class where no VFT was available and again we could demonstrate a distinct learning gain.In the last case to show the sedimentological features in preparation for the real field trip,  we could demonstrate a positive impact on the outcomes of the field excursion, thus providing an affirmative answer to the question whether VFTs can be used to prepare students for fieldwork.
Melt ponds and atmosphere-ice-ocean exchange in the UK Met Office Unified Model during the Arctic Summertime Cyclones field campaign
Authors: Barrell Christopher , Renfrew Ian , Methven John , Elvidge Andrew
Published: March 2024

Melt ponds play a key role in the Arctic sea-ice surface energy budget. Their reduced albedo compared to the surrounding ice and snow surfaces increases the absorption of short-wave radiation and enhances ice melt. Further, melt ponds affect atmosphere-ice-ocean surface turbulent exchanges of heat, moisture and momentum, which influence the structure of the overlying boundary layer. 

Simulation of melt ponds and surface exchange over sea ice in coupled numerical weather prediction models depends on parameterization schemes that need further development. However, the relationship between sea ice surface conditions and the overlying boundary layer is difficult to constrain due to the lack of in-situ observations in Arctic regions. 

We carried out the Arctic Summertime Cyclones project field campaign in July-August 2022 to make observations of sea-ice surface exchange and cyclone dynamics. Using the British Antarctic Survey MASIN Twin Otter aircraft we observed a range of sea ice surface types, some with a very high melt pond fraction during warm melt conditions, and the overlying atmospheric boundary layer. 

Using these observations to evaluate forecasts from the UK Met Office Unified Model, we show that a combination of deficiencies in the model sea ice field, melt pond representation and surface exchange parameterizations are linked to errors in the simulated boundary layer structure. In particular, the model consistently exhibits surface temperature and albedo biases over sea ice with melt ponds that act as sources of error in the surface energy budget.