bluuebunny/crossref_metadata_2025 huggingface dataset:
Re-discharges on preexisting negative leader channels of a positive cloud-to-ground lightning flash 
Authors: Sun Zhuling , Qie Xiushu , Liu Mingyuan , Li Fengquan
Published: March 2024

Using the lightning VHF interferometer, three types of discharges on the preexisting negative leader channels of a positive cloud-to-ground lightning flash were observed. The first type involved small-scale cluster discharges during the simultaneous development of the upper horizontally negative leader and downward positive leader before the return stroke. These discharges exhibited similar characteristics and radiation features as the needle-like discharges on the positive leader. Over time, their occurrence positions progressed toward the head of the negative leader, and some cluster discharges had the potential to develop into new negative branches. The other two types of re-discharges occurred after the return stroke. Immediately after the return stroke, rapid discharges initiated near the head of the negative leader, developed along the preexisting negative leader channel, and caused the decayed negative leaders to progress forward again. Subsequently, numerous lateral discharges breaking down the air occurred, distributed widely throughout the negative leader channel. These discharges developed rapidly, gradually slowing down over time until the long continuous current ended. In comparison to the positive leader discharges before the return stroke, which showed no obvious recoil leader discharges, the negative leader channel was more prone to extinguish. These re-discharges on the preexisting negative leader channel were influenced by both radial and longitudinal electric fields of flash channels, and they could also generate a backward surging current wave to sustain the discharge process on the positive leader or grounded channel.
Enhanced Continental Runoff Prediction through Differentiable Muskingum-Cunge Routing (δMC-CONUS-hydroDL2)
Authors: Bindas Tadd , Song Yalan , Rapp Jeremy , Lawson Kathryn , Shen Chaopeng
Published: March 2024

Recent advancements in flow routing models have enabled learning from big data using differentiable modeling techniques. However, their application remains constrained to smaller basins due to limitations in computational memory and hydrofabric scaling. We propose a novel methodology to scale differentiable river routing from watershed (HUC10) to continental scales using the δMC-CONUS-hydroDL2 model. Mimicking the Muskingum-Cunge routing model, this approach aims to enhance flood wave timing prediction and Manning’s n parameter learning across extensive areas. We employ the δHBV-HydroDL model, trained on the 3000 GAGES-II dataset, for streamflow predictions across CONUS HUC10 basins. These predictions are then integrated with MERIT basin data and processed through our differentiable routing model, which learns reach-scale parameters like Manning’s n and spatial channel coefficient q via an embedded neural network. This approach enhances national-scale flood simulations by leveraging a learned Manning’s n parameterization, directly contributing to the refinement of CONUS-scale flood modeling. Furthermore, this method shows promise for global application, contingent upon the availability of streamflow predictions and MERIT basin data. Our methodology represents a significant step forward in the spatial scaling of differentiable river routing models, paving the way for more accurate and extensive flood simulation capabilities.
Perspectives Through the Eyes of Primary School Students: A Visual Journey
Authors: D'Addezio Giuliana
Published: March 2024

Starting in 2005, the Istituto Nazionale di Geofisica e Vulcanologia (INGV), initiated a project involving the creation of calendars designed for schools, featuring drawings from a contest for primary school children. Each year, schools eagerly participate by submitting pupils' drawings on specific themes, which vary annually and align with Earth science subjects. Engaging primary school children in this project serves a dual purpose: it brings them closer to science and provides an opportunity to explore their perspectives on the Earth, science, the environment, and sustainable behavior. In fact, children's artwork can offer valuable insights into their feelings and thoughts about the world and its workings. Drawing plays a crucial role in children's development, as it fosters imagination and serves as an effective means of expressing emotions.Over the years, we have collected more than 35,000 drawings. We have decided to analyze this extensive and unique dataset by comparing drawings related to competitions with similar and comparable main topics, such as children's perceptions of science, scientists, and their views on the Planet Earth, its sustainability, and its future. The methodology involves a qualitative and statistical analysis of the drawings, representing the first comprehensive comparison of drawings created by primary school children across the entire Italian territory. This spans a decade or more, providing insights into how children's visions of Earth science subjects have evolved over time.Furthermore, the results contribute to evaluating how science is portrayed, assessing whether it has fostered a shared understanding and a less stereotyped image. Additionally, we aim to examine how environmental science and sustainable behavior are conveyed to the future leaders of the world. 
Precessional effects on West Africa summer monsoon intensity and duration
Authors: Shi Xiaoxu , Yang Hu , Liu Jiping , Lohmann Gerrit , Werner Martin
Published: March 2024

The changes of summer monsoon precipitation over West Africa has been well documented for the past climate. However, the specific changes in the onset, withdrawal, and duration of the WASM have not been explored extensively due to the lack of high temporal resolution reconstructions.Solar insolation, which reaches its maximum during boreal summer, acts as the primary energy source for the monsoon system. The precession of Earth's orbit regulates the occurrence of perihelion and aphelion and the length of the summer season. To examine the role of precession on the WASM, we conducted 24 time-slice simulations, altering the precession angle from 0° to 345° with a 15° interval.Using simulated daily precipitation for West Africa, we analyzed the intensity, onset, withdrawal, and duration of the summer monsoon in our model study. Our findings reveal that precession has a significant influence on the intensity and duration of the WASM. Generally, during the northern summer, if Earth is closer to perihelion, the WASM tends to be stronger but shorter. Conversely, if Earth is closer to aphelion, the WASM is weaker but has a longer duration.These results emphasize the importance of considering the orbital effect on the WASM intensity and duration over a precessional cycle.
eLMA: Supercells over the Upgraded Ebro 3D Lightning Mapping Array and High-speed Observations of Lightning in the Near-Ultraviolet
Authors: van der Velde Oscar , Romero David , López Jesús , Montanyà Joan , Pineda Nicolau
Published: March 2024

In 2011, the Ebro 3D Lightning Mapping Array was the first LMA installed outside the USA, consisting of 12 stations in 2012-2014 and was subsequently split in half in 2015 to facilitate a LMA in Colombia.Thanks to research infrastructure service funding from the Spanish government and the European Union (MCIN/AEI/10.13039/501100011033/ and NextGenerationEU, project EQC2021-006957-P), the Ebro LMA has been upgraded to a wider area network operating 15 latest technology LMA stations operating on solar power in the Ebro Valley region (western Catalonia and eastern Aragón). New services are offered: (1) Real-time tracking of lightning flashes across northeastern Spain, available to the public via the website elma.upc.edu. (2) Archive of plotted data that can be browsed freely, including for the old Ebro LMA data. (3) Raw/processed data can be requested. (4) LMA rental is possible for field campaigns.We developed a new processing & visualization tool for flash/thunderstorm analysis and future integration with the new EUMETSAT Lightning Imager (LI). It is written in the Julia programming language for its speed of processing with the Makie interactive graphics package. Additionally, we present a new tool for displaying regional maps of actual (not computed) LMA station contributions to assess the network performance. The capabilities of the new Ebro LMA are showcased with record-setting horizontal lightning flashes, several large-hail producing supercells with high flash rates, a lightning hole, and rising turrets of small flashes and sparks at the cloud top, which can now be isolated and analyzed with the Julia visualization tool. The electrical evolution features of these supercells are examined in relation to their timeline of severe weather production.Additionally, a Vision Research Phantom TMX 6410 and UV-sensitive Lambert HiCATT 25 image intensifier with optics and filters were acquired, and is also available to third parties via eLMA rental services. During spring/summer 2023 it has been successfully used to image lightning leaders through a 337 nm optical narrowband filter (10 nm width) similar to imaging systems of the Atmosphere-Space Interactions Monitor (ASIM), at speeds of 65,000 to 320,000 frames per second. We found that observation distances 418 ms long continuing current negative return stroke (cut off by end of buffer) was observed. Also, the system captured elves, nocturnal optical emissions at the base of the ionosphere (85 km) over Mediterranean winter thunderstorms, clearly showing the typical double-wave structure originally reported by photometer arrays.
The Impact of Volcano-Generated Tsunamis on the Safety of Moored Vessels: The 2022 Tonga Incident.
Authors: Padilla Álvarez Sergio , Quiroga Iñigo Aniel , Gonzalez Mauricio , Omira Rachid , Kim Jihwan , Baptista Maria Ana
Published: March 2024

The atmospheric tsunami resulting from the eruption of the Tonga volcano on January 15, 2022 (Tonga22) marked an unprecedented occurrence, encompassing a Volcano-Meteorological Tsunami (VMT) with global ramifications. This study examines the comprehensive effects of Tonga22 on moored vessels, employing a spectral and hydrodynamic analytical framework. The aftermath of the event, including edge waves, resonance phenomena, and wave amplification in specific regions such as La Pampilla port in Peru, revealed substantial maritime challenges. Notably, a vessel in La Pampilla reported the rupture of mooring ropes, a remarkable incident occurring 10,000 kilometers away from the Tonga volcano, manifesting 15 hours post-eruption and resulting in the spillage of over 11,000 barrels of crude oil.Our research aims to contribute to a nuanced understanding of the Tonga22 event by employing advanced spectral and hydrodynamic analyses. The primary focus lies in assessing its impact on mooring loads within the complex marine port environment. We postulate that atmospheric acoustic waves, a consequence of the volcanic eruption, pose hydrodynamic threats to vessels in port areas, potentially leading to mooring breakage.Utilizing the Boussinesq model, validated at the local scale in Callao Bay, we establish a foundation for our mooring system model. This model, applied to a vessel analogous to the one docked at La Pampilla Port, aims to discern the nuanced influence of VMT on overstressing and mooring breakage during the Tonga22 event.Our simulation results underscore the pivotal role of VMT in the displacement and loss of positioning of vessels. Moreover, atmospheric waves are revealed to significantly elevate mooring stresses, with a particular emphasis on the starboard quarter moorings in this specific case.This research sheds light on a critical realization—the Tonga22 event highlights the inadequacies of existing tsunami early warning systems (TWC) in detecting and managing tsunamis induced by acoustic waves originating from volcanic sources. These findings contribute to the ongoing discourse on maritime safety and hazard preparedness.
The Stratospheric Gravity Wave Field and Momentum Fluxes Produced by Isolated Supercells
Authors: Rosamond Luke , Nolan David , Dai Yi , Heale Chris
Published: March 2024

Alongside topographic forcing, deep moist convection makes a significant contribution to the global budget of upward momentum transport by gravity waves. Long-lived thunderstorms with rotating updrafts, known as supercells, produce strong and highly variable vertical motions over several hours. This study uses an idealized modeling framework in WRF to simulate supercells and their associated gravity waves up to 60 km altitude for multiple different wind profiles and convective modes. In contrast to many previous studies, the supercell is brought to an end and the simulations continue until most of the wave energy has dissipated. Thus, upward momentum transport can be computed over the entire life cycle of the storm and its associated waves, providing a more complete picture of the total impact of the event. The shapes of the wind profiles in the upper troposphere and lower stratosphere are found to strongly control the total momentum and energy transported into the upper stratosphere, so varying the stratospheric wind profile illuminates the behavior of the gravity waves in the stratosphere, particularly their vertical propagation. We also investigate the extent to which different modes of supercell structure, such as high-precipitation, low-precipitation, and classic supercells, lead to different intensities and spectra of the resulting gravity waves. In addition, the WRF model diabatic heating and vertical motions will be used as forcing conditions for stratospheric models such as MAGIC and CGCAM for the purposes of 1) comparison to WRF results between 20 and 60 km, and 2) so that wave propagation, momentum transport, wave breaking, and momentum deposition can be evaluated to altitudes above 80 km.
Inverse hydrological modeling to infer historical snow mass based on streamflow records
Authors: Wiersma Pau , Mariéthoz Grégoire
Published: March 2024

Mapping the dynamics of snow water equivalent (SWE) is critical for understanding the hydrology of mountain regions. While methods to reconstruct SWE exist, they usually rely on either remote sensing data or the presence of in-situ observations. Streamflow observations can be considered an indirect and delayed observation of catchment-wide SWE, but despite their broad spatial and temporal availability, their potential for SWE reconstructions has not been explored so far.In this study, we investigate how much SWE information can be extracted from the streamflow record, both in terms of its total mass as well as its spatial distribution. To this end, we set up an inverse streamflow-based SWE reconstruction framework that can operate without remote sensing data or in-situ snow observations. As a basis, we use a distributed hydrological model with a temperature-index snow model at 1km resolution, which generates SWE reconstructions from a set of prior snow and climate parameters and translates them into streamflow. By using the streamflow observations to optimize these parameters, we obtain SWE reconstructions that better match the streamflow.However, there is likely a multitude of SWE reconstructions that all lead to the same streamflow, which is defined as an ill-posed inverse problem. In order to find out by how much the streamflow can constrain the prior SWE reconstructions, we perform an experiment with synthetic observations. Using synthetic observations instead of real observations eliminates both model and observation errors, allowing us to focus solely on the nature of this ill-posed problem.Firstly, we select a set of soil, snow and climate parameters to generate synthetic SWE observations and their corresponding streamflow. All parameters are kept constant over the entire period except the parameter controlling the snowfall bias correction, which is set to fluctuate on a yearly basis and consequently also needs to be optimized for each year separately. Then, we run a single calibration to attempt to rederive these parameters and reconstruct the synthetic observations. Finally, we analyze our posterior ensemble of parameter sets and SWE reconstructions and quantify the resemblance to the synthetic streamflow and SWE observations. We expect to find a near-perfect match with the synthetic streamflow observations, a strong constraint of the total catchment-wide SWE but a weak constraint of the spatial distribution of this SWE.
Microplastics in the Alpine watercycle – A combination of methods to cover the widest possible size range 
Authors: Liedermann Marcel , Pessenlehner Sebastian , Mayerhofer Elisabeth , Schöner Wolfgang , Ribitsch Doris , Gübitz Georg , Gmeiner Philipp
Published: March 2024

Plastic waste as a permanent pollutant in the environment is of increasing concern due to its largely unknown long-term effects on biota. The occurrence in rivers, has, compared to research in the oceans, only become the focus of scientific investigations in the last few years. The Austrian Alps in particular are largely unexplored in this respect. Therefore, the Alplast project addresses microplastic transport from the glaciers at the summit over steep mountain torrents to the lowland rivers and aims in conducting a first inventory of the alpine area. Specifically, analyses of microplastic occurrences are being carried out from the Sonnblick glacier via the Rauriser Ache, the Salzach, the Inn and the Danube and are intended to expand the understanding of processes with regard to the behaviour of microplastics in the water cycle from the glacier to the valley. The influence of snowmelt as well as the temporal development, which can be determined from ice cores, are of great interest. In addition, questions regarding the origin and distribution of plastic in flowing waters as well as the possible biological degradation by microorganisms will be clarified.Since the sampling areas cover entire catchments at different altitudes, different methodologies and devices are used. For the studies on the glaciers, the snow cover as well as ice cores are sampled and analysed. In the rivers a multi-point method is used due to the spatial distribution of plastic particles in the river cross-section. But the net samples at different depths are combined with isokinetic pump sampling in order to detect the widest possible size range. Isokinetically taken pump samples have the great advantage that a weighting process takes place directly during sampling. This means that samples can be taken in different areas (high and low flow velocities) of the cross-section (together with the nets) and then a composite sample can be analysed for the profile. Particle counts, classification and the measurement of concentrations and loads are then used to determine quantities and the most common types of plastics in the alpine environment. The measuring stations were selected in such a way that more and more potential microplastic sources are added in the course of the catchment in order to achieve the best possible process understanding regarding the origin and fate of the plastic waste.
Understanding the Amazon's Atmospheric Hydrology: Insights from ERA5 Data and Directional Transport Analysis 
Authors: Sanchez Hernandez Karel Aldrin , Corzo Perez Gerald Augusto , Santos Granados German Ricardo , Gacharna Gonzalez Juan Manuel , Tami Riveros Carlos Alfredo , Hernandez Torres Guillermo , Herran Gustavo , Gutierrez Diego , Rubiano Fabio
Published: March 2024

The atmospheric dynamics of the Amazon, critical for global environmental stability, have faced increasing influence from numerous El Niño and La Niña events in recent decades. While reanalysis data has incorporated these events through models and measurements, the intricate mechanics of spatial and temporal water vapor transport remain unclear. In this study, we present a preliminary analysis of these dynamics, utilizing over twenty years of ERA5 monthly data over atmospheric layer. Our investigation was constructed on two primary scales, each offering unique insights. The first scale aims to replicate and validate the system's seasonality concerning the Intertropical Convergence Zone (ITCZ), those patterns allow evaluating some patterns and its effects in land hydrological process observed along the basin integrating specific methods and models to clarify how the seasonality was replicated and validated. On the second scale, we delve into smaller hydrological sub-units of the Amazon, identifying their contribution to water recycling, and net fluxes across the basin boundaries. We provide an innovative estimation of transport paths using a 4 cardinal directional approach (brubaker box scheme modified) that makes possible identificate, analyse and understanding, water sources and sinks and its relevance in the normal hydrological production and synergically systems 

The findings indicate the system's relatively stable dynamics in terms of water vapor sources and altitudinal variation across atmospheric layers. Our methodology introduces a novel framework for calculating comprehensive trajectories of water vapor transport from a hybrid lagrangian-eulerian approach, significantly enhancing our understanding of the Amazon's hydrological cycle from an atmospheric perspective. 

To provide more precision, we specify that the stability observed in the system pertains to water vapor sources and altitudinal variation. These stable dynamics contribute valuable insights into the intricate water vapor transport mechanisms in the Amazon. Additionally, we highlight the implications of our findings for future research in understanding how to create alternatives to mitigate some impacts of El Niño and La Niña events on the Amazon's atmospheric dynamics. 
The role of the arts in a community-based participatory research project
Authors: Macouin Melina , Tastevin Yann-Philippe , Dutrait Claire
Published: March 2024

Recycling metals such as iron and lead appears crucial for sustainable development, but metal recycling often results in poor quality of life for people living near recycling sites. Transdisciplinary approaches, involving researchers from the physical, natural, and social sciences and humanities working with non-academic partners, are now recognized as essential for tackling such a challenging Anthropocene issue. However, collaboration and understanding between partners are often hampered by the specific modes of communication and concepts used by each community.We present here the beneficial role of the arts in a community-based participatory research project addressing the impacts of metal recycling activities in West Africa, particularly in terms of air pollution. In Senegal (Africa), the town of Sébikotane has become a rapidly growing urban center with three recycling plants (steel and lead batteries). The project aims to produce, jointly evaluate, and share knowledge on air quality in this urban area in transition, far from official measurements. The team includes researchers from geosciences, aerology, anthropology, literature, and botany. Artists, the city council, an NGO, and citizens are officially and actively involved in the project as non-academic partners.We will show how the different artistic productions helped to implement and share knowledge along the project, especially the participatory part, and promoted efficient communication between all partners. Forum theater, live sketching, literature, and design provided effective artistic means to translate concepts and share knowledge. The collaboration between artists and scientists facilitated the elaboration of ethical rules governing the project's stance.
 DeepFuse: Towards Frequent Flood Inundation Monitoring using AI and EO
Authors: Dasgupta Antara , Sahu Rakesh , Hybbeneth Lasse , Waske Björn
Published: March 2024

Despite the increase in the number of Earth Observation satellites with active microwave sensors suitable for flood mapping, the frequency of observations still limits adequate characterization of inundation dynamics. Particularly, capturing the flood peak or maximum inundation extent, still remains elusive and a major research gap in the remote sensing of floods. Rapidly growing archives of multimodal satellite hydrology datasets combined with the recent deep learning revolution provide an opportunity to solve this problem adequate observation frequency. DeepFuse is a scalable data fusion methodology, leveraging deep learning (DL) and Earth Observation data, to estimate daily flood inundation at scale with a high spatial resolution. In this proof-of-concept study, the potential of Convolutional Neural Networks (CNN) to simulate flood inundation at the Sentinel-1 (S1) spatial resolution is demonstrated. Leveraging coarse resolution but temporally frequent datasets such as soil moisture/accumulated precipitation data from NASA’s SMAP/GPM missions and static topographical/land-use predictors, a CNN was trained on flood maps derived from S1 to predict high-resolution flood inundation. The proposed methodology was tested in southwest France at the confluence of its two main rivers, Adour and Luy, for the December 2019 flood event. The predicted high-resolution maps were independently evaluated against flood masks derived from Sentinel-2 using the Random Forest Classifier. First results confirm that the CNN can generalize some hydrological/hydraulic relationships leading to inundation based on the provided inputs, even for some rather complex topographies. However, further tests in catchments with strongly divergent land-use, hydrological, and elevation profiles is necessary to evaluate model sensitivity towards different land surface conditions. Achieving daily cadence for flood monitoring will enable an improved understanding of spatial inundation dynamics, as well as help develop better parametric hazard re/insurance products to effectively bridge the flood protection gap.
The potential for neutral tori at Uranus and Neptune
Authors: smith howard
Published: March 2024

Neutral Tori are generally a result of particles escaping from a planetary atmosphere, its rings or satellites through internal source mechanisms or interactions with the magnetosphere. These particles then form a population of co-orbiting neutral particles that provide a source of plasma to the magnetosphere as well as drive dynamics and chemistry. Thus, understanding neutral tori provides key (sometimes unique) insight into planetary magnetospheres, moon source characterization and understanding, and ultimately can provide insight to past, present and future of magnetospheres. Current increased neutral torus research had provided significant insight into Saturn and Jupiter’s magnetosphere and gas giants in general. These results indicated great potential for improving our understanding the magnetospheres of Uranus and Neptune whose orientations offer the possibility of magnetospheric configurations not previously observed. Here, we will discuss how the Gas Giant neutral torus state of understanding has signifcaintly increased and may provide an analogy for what we may expect from studying these features on Ice Giants. We also present some preliminary modeling to speculate on the possible presence of neutral tori at Uranus and Neptune.
Agroclimatic zoning methodology for selection of suitable crop in water limited Mediterranean areas
Authors: Faraslis Ioannis , Dalezios Nicolas , Alpanakis Nicolas , Tziatzios Georgios , Spiliotopoulos Marios , Sakellariou Stavros , Sidiropoulos Pantelis , Dercas Nicholas , Brissimis Vagelis
Published: March 2024

The agroclimatic classification identifies zones for efficient use of natural resources leading to optimal crop production. In water limited availability regions, such as the Mediterranean region, one problem is the quantification of water use in agriculture in view of the social problems linked to the performance of irrigated systems. The aim of this paper is the development of agricultural sustainable zones, in a typical water limited Mediterranean region, namely Thessaly in Greece. To achieve this, time series analysis with sophisticated geoinformatics techniques is applied. The agroclimatic classification methodology is based on three-stages: first, the microclimate features of the region are considered using aridity and vegetation health indices leading to water limited growth environment (WLGE) zones based on water availability; second, landform features and soil types are associated to WLGE zones to identify non-crop specific agroclimatic zones (NCSAZ); finally, specific restricted crop parameters, are combined with NCSAZ creating the suitability zones for sustainable agriculture. The results are promising as compared with the current crop production systems of the study area under investigation. Due to climate change, the results indicate that arid and semi-arid regions are also faced with insufficient amounts of precipitation for supporting rainfed annual crops. Finally, the proposed methodology reveals that the combination of Remotely Sensed techniques could be a significant tool for creating, shortly, detailed and up to date agroclimatic zones.Keywords: Agroclimatic zoning; Hydroclimatic zoning; Non-crop specific zoning; Crop-specific zoning; Agricultural suitability zones, Mediterranean agroecosystems
Machine Learning Based Closure Optimization for the Unified Convection Parametrization 
Authors: Nascimento Janaina , Banducci Alessandro , Li Haiqin , Grell Georg
Published: March 2024

The EMC Unified Convection (UC) parameterization combines the Simplified Arakawa Schubert (SAS) and Grell-Freitas (GF) convective parameterizations in order to improve performance on regional and global scales. The UC parameterization uses the average of an ensemble of closures to determine the strength and location of convection. Deficiencies in optimizing the selection of these closures, used in deep convection parameterizations in General Circulation Models (GCMs), at different scales and in changing environmental conditions have critical impacts on climate simulations. Some closures may produce more accurate output in particular environmental conditions but currently the GF parametrization takes a uniform average over all closures. This work uses Machine learning (ML) methods combined with satellite and global model datasets in order to weight the closure average based on location and meteorological conditions. First dimensionality reduction techniques are applied in order to define a set of conditions where certain groups of closures tend to perform better. From these groups a weight vector is generated from the relative error each closure demonstrates compared with observations. A decision tree is then responsible for deciding which weight vectors are best in particular environmental situations. One advantage of this approach is that it is explainable; a human expert familiar with the behaviors of the closures (the conditions where they perform best/worst, etc.) can determine why the decision tree chose the particular weight vector.
Combining Neural Networks and Data Assimilation to enhance the spatial impact of Argo floats in the Copernicus Mediterranean biogeochemical model
Authors: Amadio Carolina , Teruzzi Anna , Pietropolli Gloria , Manzoni Luca , Coidessa Gianluca , Cossarini Gianpiero
Published: March 2024

Biogeochemical-Argo (BGC-Argo) float profiles provide substantial information for key vertical biogeochemical dynamics and successfully integrated in biogeochemical models via data assimilation approaches. Although results on the BGC-Argo assimilation are encouraging, data scarcity remains a limitation for their effective use in operational oceanography. To address availability gaps in the BGC-Argo profiles, an Observing System Experiment (OSE), that combines Neural Network (NN) and Data Assimilation (DA), has been performed here. NN was used to reconstruct nitrate profiles starting from oxygen profiles and associated Argo variables (pressure, temperature, salinity), while a variational data assimilation scheme (3DVarBio) has been upgraded to integrate BGC-Argo and reconstructed observations in the Copernicus Mediterranean operational forecast system (MedBFM). To ensure high quality of oxygen data, a post-deployment quality control method has been developed with the aim of detecting and eventually correcting potential sensors drift. The Mediterranean OSE features three different setups: a control run without assimilation; a multivariate run with assimilation of BGC-Argo chlorophyll, nitrate, and oxygen; and a multivariate run that also assimilates reconstructed observations. The general improvement of skill performance metrics demonstrated the feasibility in integrating new variables (oxygen and reconstructed nitrate). Major benefits have been observed in reproducing specific BGC process-based dynamics such as the nitracline dynamics, primary production and oxygen vertical dynamics. The assimilation of BGC-Argo nitrate corrects a generally positive bias of the model in most of the Mediterranean areas, and the addition of reconstructed profiles makes the corrections even stronger. The impact of enlarged nitrate assimilation propagates to ecosystem processes (e.g., primary production) at basin wide scale, demonstrating the importance of BGC profiles in complementing satellite ocean colour assimilation.
Imaging the Northeastern End of the Mw7.7 Ekinozu Earthquake Rupture along the Çardak-Surgu Fault during the 2023 Kahramanmaraş, Türkiye, Earthquake Doublet
Authors: Delorme Arthur , Yao Wenqian , klinger Yann
Published: March 2024

The Mw 7.7 Ekinozu Earthquake is the second shock of the devastating 2023 Kahramanmaraş earthquake doublet. It ruptured bilaterally along a ~150 km-long stretch of the Cardak-Surgu fault. Along its eastern section, instead of propagating along the Surgu fault to connect with the main East Anatolian Fault where the Mw7.8 shock occurred, the rupture unexpectedly turned to the northeast to propagate along a secondary structure. Surface ruptures and assessment of displacement along that section of the fault have been challenging to map, and these are less documented. This is crucial for unraveling the entire rupture process, fault growth, and related seismic hazards. In this study, we focus on the eastern end of the ~57-km long surface rupture caused by the Mw 7.7 Ekinozu Earthquake. By correlating high-resolution optical images SPOT (pre-earthquakes, resolution 1.5m) and Pléiades (post-earthquakes, resolution 50 cm), we computed displacement maps at 1.5 m ground resolution for the study area. In addition, using the post-event Pleiades images, we meticulously characterized the coseismic surface ruptures in detail. Our mapping presents a segmented surface rupture trace with azimuth variations and several distinguishably complex geometries, such as double bends and branches. Furthermore, our investigation includes precise measurements of on- and off-fault surface displacement with sub-pixel detection over the ~57-km long section. Our findings underscore the significance of detailed interpretations of coseismic surface rupture and coseismic displacement measurements in comprehending the propagation of the seismic rupture.
Testing for adaptation in the observed corn and soy yields in the US Midwest
Authors: Raghuram Adarsh , Coffel Ethan
Published: March 2024

The positive effects of warm temperatures on crop yields reverses beyond a critical temperature threshold, where sharp decrease in yields is observed for all crops. In the light of warming trends observed globally, adaptation of crops to extreme climatic conditions could be crucial for ensuring a stable food supply in the future. While numerous studies have shown the potential positive impact of adaptation on food security, there is limited evidence showing observed changes in the sensitivity of major food crops to high temperatures at national and global levels. In this study, we use regression models to examine the spatiotemporal variations in critical temperature threshold for corn and soy in the US Midwest. Further, we also examine changes in yield response to exposure to temperatures beyond the critical temperature threshold. Overall, our work tests for the presence of adaptation in the observed yield trends of corn and soy in the US Midwest. 
Impact of cyclic thermal loading on thermal convection along a high-temperature borehole heat exchanger: Laboratory-scale experimental and numerical study
Authors: Djotsa Nguimeya Ngninjio Victorien , Beyer Christof , Bauer Sebastian
Published: March 2024

A series of combined laboratory scale experiments and numerical simulations of a high-temperature borehole heat exchanger (BHE) in a geological porous medium was carried out under dynamic cyclic thermal loading. The main objective of this work was to investigate the influence of the transient charging/discharging cycle time scales on thermal convection and heat transfer characteristics. The experimental unit was constructed with a vertical, grouted coaxial BHE installed in the center of a water saturated coarse sand within a 1.4 m3 cylindrical barrel. Five cyclic experiments at 70°C charging temperature and cycle durations of 6, 12 and 24 hours after a pre-charging phase, and 6 and 12 hours without pre-charging were conducted under well controlled conditions. A dense sensor grid of 129 thermocouples was deployed to record the evolution of the temperature distribution inside the unit and across the boundary. A 2D-axisymmetric numerical model of the experimental unit was developed in OpenGeoSys and validated for the coupled thermo-hydraulic processes in the porous medium by comparison to previously performed short-term static charging/discharging experiments. The model then was applied to simulate the experiments presented here. The model-to-data comparison indicated a very good agreement, and thus was further used to analyse the impact of the cyclic operation on the contribution of thermal convection to overall BHE heat transfer.The results indicated a cumulative increase of sand temperature levels during the first cycles in the experiments without pre-charging and a decrease when cyclic operation was started after a stationary pre-charging stage, until a quasi stable behavior was reached between consecutive cycles. In general, the difference in obtained results between both operating modes for a given cycle duration was only observed within the first three to four cycles. An increase of the magnitude of convective flow characterised by increases of heat transfer rates, Rayleigh numbers, buoyant flow velocities, and temperature gradients with the cycle duration from 6, 12 to 24 hours was found. The estimated contribution of thermal convection to heat transfer at the last cycle decreased from 23% at 24 hours cycle duration to 20% and 18% at 12 and 6 hours with pre-charging, and 21% and 16 % without pre-charging, respectively. These results demonstrate that for the given experimental setup and scale, convective flow can no longer fully develop within the shorter dynamic charging cycle durations, and thus is less effective for increasing the BHE-to-sand heat transfer during heat charging.
Determining influencing factors of climate-growth relationships of European beech across its ecological amplitude
Authors: Leifsson Christopher , Buras Allan , Rammig Anja , Zang Christian ,   Beech Network
Published: March 2024

The prospect for European beech forests (Fagus sylvatica L.) over the course of the 21st century is uncertain due to climate change. In context, climate sensitivity of growth is a valuable indicator of physiological integrity, but its natural variability is poorly understood in productive, closed canopy forests. Climate sensitivity may not only depend on temporal and spatial differences in climatic conditions, but also on trees’ rank progression in the course of forest maturation.Here, we determine how the drought sensitivity of secondary growth in beech varies in space and time according to growth trends, growth variability and climatic conditions. The temporal variability of these variables is determined via a moving window approach using a network of tree-ring sites across the species’ geographical and climatological distribution. The moving window derived variables are applied to a linear mixed-effects model allowing for the estimation of linear, non-linear and interactive effects. Furthermore, dry and wet subsets of the data are supplied individually to determine differences between dry and wet site conditions.Our results indicate considerable variability in climate sensitivity due to complex non-linear and interactive effects of all variables. Generally, drought sensitivity is strongly and positively coupled with growth variability and climatic aridity. The strong non-linear and interactive effects between all variables result in drought sensitivity changing considerably with changes in growth variability and growth trends when climatic conditions are average or wetter than average. However, during dry time-periods, drought sensitivity is consistently high and decoupled from changes in growth trends and growth variability. While these patterns remain relatively similar between dry and wet sites, dry sites show significantly higher drought sensitivity compared to wet sites overall.In conclusion, we found beech’s drought sensitivity to be significantly affected by growth variability, growth trends and climatic conditions. Furthermore, the influence of each variable on drought sensitivity changes drastically as they interact, indicating all these factors need to be considered when interpreting beech’s climate sensitivity.
Development of a Web-Based Decision Support System for Watershed-Scale Agricultural Conservation Management in the United States
Authors: Ozeren Yavuz , Rébillout Luc , Sahin Ahmet , Pophet Nuttita , Al-Hamdan Mohammad , Bingner Ron
Published: March 2024

An automated Web-based decision support tool, Agricultural Integrated Management System (AIMS) is developed to evaluate the impacts of agricultural and channel conservation management practices within any watershed in the United States. AIMS offers a user-friendly Web-GIS framework, enabling convenient interaction with geospatial data layers, automated input data preparation for AnnAGNPS model and visualizing watershed simulation results on any device with internet access. AIMS uses the watershed-scale simulation tool of the USDA Agricultural Research Service (ARS), the Annualized Agricultural Non-Point Source Pollution (AnnAGNPS) model to estimate the runoff, sediment, nutrients, and pesticides that may originate from agricultural areas and impact water quality in rivers, streams, and other water bodies. Running the AnnAGNPS model requires various datasets including topographic, soil, land use and land cover, climate, management data. The topographic data consists of concentrated flows (reaches) and sub-catchments (cells) which are delineated for the entire United States using TopAGNPS, a topographic parameterization program for AnnAGNPS. Soil data is obtained from NRCS Soil Data Access service and processed to produce aggregated data for AnnAGNPS. Historical climate data is derived from the North American Land Data Assimilation System Phase 2 (NLDAS-2) obtained from Hydrology Data Rods. Where NLDAS-2 is unavailable or incomplete, the climate data is supplemented using Daily Surface Weather and Climatological Summaries (DAYMET). The land use data includes the spatial information about the land cover (such as crops) and the management data includes the agricultural operation (such as scheduling of tillage, planting, fertilization, harvesting etc.) performed in the region. The assimilation of the management data to AIMS is currently underway. This presentation summarizes the development of the AIMS framework, dataset preparation for the models, and displays the capabilities of AIMS.
POSEIDON Project: Seismic Hazards in the western Peloponnese - Ionian Islands Domain
Authors: Ranero César R. , Nomikou Paraskevi , Loreto Filomena , Merino Irene , Ferrante Valentina , Lampidou Danai , Nikoli Elisavet , Poulos Serafeim
Published: March 2024

The cruise POSEIDON from 10-22 June 2023, mapped the tectonic structure of the region extending from the western Peloponnese across the Ionian Islands. This is one of the most complex and comparatively little evaluated regions, with demonstrated seismic hazard, in the Mediterranean.The region contains a complex fault system with numerous strands controlling much of the submarine and subaerial relief and with dramatic lateral changes in deformation rates. The fault system has produced large earthquakes, mostly offshore, recorded during the past few decades in the Greek national seismological network. However, the largest recent Mw~6.8-7.0 Kephalonia 1953 event was recorded in few stations available then. This earthquake - possibly the most destructive in recent Greek history - cause the collapse of ~85% of all buildings on Kephalonia Island, ~1k deaths, and ~145k people homeless. However, the 1953 earthquake is poorly understood compared with more recent, albeit less destructive events. The epicentre of the 1953 event is not well constrained, and the location and dimensions of the causative fault are unknown. Likewise, the hypocenter depth of the 1953 event thrust-fault focal mechanism, that occurred E or SE of Kefalonia, is defined from
What controlled the Mediterranean Sea level during the Lago-Mare stage of the Messinian salinity crisis?
Authors: Garcia-Castellanos Daniel , Heida Hanneke , Palcu Dan , Aloisi Vanni
Published: March 2024

Stratigraphic and geochemical evidence suggests that the Mediterranean Sea underwent widespread salinization and a kilometer-scale evaporative drawdown between 5.97 to 5.33 million years ago, during the period known as the Messinian salinity crisis (MSC). The mechanisms responsible for the accumulation of one million cubic kilometers of salt on the sea floor and the impact on terrestrial and marine fauna and on climate are being better understood in the last decades. However, the presence of relatively fresh water sediment containing fossil fauna of eastern (Paratethyan) provenance in the last stages of the MSC poses severe problems to understand the ending of the crisis. These brackish-water deposits, known as the Lago-Mare unit, are sometimes found at elevations close to the present sea level, in apparent contradiction with the coetaneous evaporitic sediment found in deeper, central parts of the Mediterranean. We make use of landscape evolution models calibrated with sediment transport and river incision data to explore plausible scenarios of climate and sea level changes during the MSC. The results show that, upon full isolation, the large initial evaporative sea level fall of the Mediterranean leads to a progressive capture of the waters from nearby lacustrine basins such as the Black Sea or the Pannonian Basin. This drainage area expansion triggers a gradual sea level rise in the Mediterranean. Milankovic climate oscillations superimposed to this trend lead to large-amplitude (500-1000 m) harmonic sea level variations reaching ever-higher levels. This is consistent with the salt precipitation in deeper areas during lowstands and Lago-Mare deposition during highstands in marginal areas. This model may also explain the seemingly contradiction between the high-level Lago-Mare deposits and the km-scale sea level drop estimated from erosion markers and implicit in the Zanclean cataclysmic reflooding model.