bluuebunny/crossref_metadata_2025 huggingface dataset:
Indicators of the Activity Associated with Concealed Feeding Volcanic Fluids in the Tatun Volcano Group, Northern Taiwan
Authors: Pu Hsin-Chieh , Lin Cheng-Horng , Lee Hsiao-Fen , Lai Ya-Chuan , Shih Min-Hung , Hong Guo-Teng , Lee Po-Tsun
Published: March 2024

We analyzed 3,330 earthquake focal mechanisms and the fumarolic gases in the Tatun Volcano Group (TVG) during 2018–2021. Between June/2020 and June/2021, we found a concealed inflation beneath a depth of 2 km. We indicate this inflating mechanism was associated with the feeding volcanic fluids, which induced the past inflating cases in the TVG before 2018. We deliberated about the feeding features regarding this and the past cases and purpose three indicators to monitor such concealed activities, including the inflating indicator associated with the behaviors of earthquake faulting, heating indicator determined by the systematically high HCl/CO2 ratios, and discharging indicator displayed by the lasting high St/CO2 ratios. Using these indicators, we concluded that it was not rare during the last one decade that the concealed activities whose volcanic fluids were discharged occasionally.
Adaptions of tree individual morphology and stem wood density to multiple climate and soil characteristics gradients
Authors: Song Xiang , Li Jinxu , Zeng Xiaodong
Published: March 2024

The tree height–diameter at breast height (H–DBH) and crown radius–DBH (CR–DBH) relationships as well as wood density are key for forest carbon/biomass estimation, parameterization in vegetation models and vegetation–atmosphere interactions. Although the H–DBH relationship has been widely investigated on site or regional scales, and a small amount of studies have involved CR–DBH relationships based on plot-level data, few studies have quantitatively verified the universality of these two relationships on a global scale. Moreover, in current Earth System Models/Dynamic Global Vegetation Models (ESMs/DGVMs), wood density is also oversimplified, being defined either as a uniform constant or as plant functional type-dependent (PFT-dependent) constants worldwide. Such oversimplifications may lead to simulation biases in morphology of woody PFTs, ecosystem transition and vegetation-atmosphere interactions.In our study, the ability of 29 functions to fit the H–DBH and CR–DBH relationships for six different plant functional types (PFTs) are evaluated on a global scale, based on a global plant trait database. Then, the relationships between H-DBH, CR-DBH, wood density and climate are investigated. This work provides a valuable foundation for parameterization improvements in vegetation models, and some clues to forest field investigations.
Application of marine organisms at multi-trophic level to study the integrated biological responses induced by microplastics through food-chain
Authors: Di Yanan , Zhao Ruoxuan , Xu Jianzhou
Published: March 2024

Microplastics (MPs, smaller than 5 mm) are ubiquitous and difficult to be degraded in environment. It is more easily to be ingested by the organism and cause a series of harms through the food chain. Based on the survey of MPs distribution in the intertidal zone along our coast and the development of fast MPs detection methods by using Hyperspectral image recognition, we use a typical marine food chain (microalgae-mussels-crabs) to investigate the trophic transfer and the relative toxic effects by environmental MPs. The polyethylene particles (10-45 μm) was selected as representative MPs to investigate the induced biological effects in microalgae, marine mussels and crabs, and the potential mechanisms under different exposure scenarios, including both water-born and trophic transfer exposure. The results showed that the algae could absorb on the surface of MPs, which not only damaged algal cells, but also changed surface characteristics of MPs to affect the feeding of mussels. In addition, MPs could be ingested and accumulated in the consumers with significant exposure concentration dependence and tissue specificity. Biomarkers from different levels in mussels and crabs showed that MPs could induce the increased ingestion rate, decreased lysosomal membrane stability, the changes of the activity of antioxidative responses. In addition, MPs indeed caused more serious stress responses in organisms at higher levels in food chain through the trophic transfer under the mechanism to balance the antioxidant defenses and metabolism system. To our best knowledge, this research is the first study to focus on trophic transfer induced biological responses by MPs in marine organisms. It provides an important research model and scientific basis for the future exploration of eco-toxic effect of environmental MPs.
Implementation of machine learning approaches to monitor pre-eruptive swarms at Piton de la Fournaise volcano
Authors: Menager Marine , Duputel Zacharie , Retailleau Lise , Ferrazzini Valérie , McBrearty Ian
Published: March 2024

Eruptions of Piton de la Fournaise volcano (Reunion Island, France) are preceded by intense pre-eruptive seismicity swarms characterized by hundreds, or even thousands of micro earthquakes (magnitude < 2). These volcano-tectonic events are triggered by the upward migration of magma toward the surface and their location provides important information regarding the future eruption location. Yet, regarding the large number of earthquakes, it is difficult to locate them all during seismicity swarms. Hence, we have implemented an approach at the Piton de la Fournaise Volcano Observatory (OVPF-IPGP) based on machine learning to automatically detect and locate these events.. First, we use PhaseNet to pick P and S waves from 17 seismic stations installed on and around the volcano. Then, phase association and source location are done using a Graph Neural Network (GNN) approach called GENIE (Graph Earthquake Neural Interpretation Engine). To implement GENIE specifically at Piton de la Fournaise, we trained the code with seismic stations and velocity models used by OVPF-IPGP to monitor the volcano.. After phase association, we perform a final hypocenter localization using the probabilistic approach of NonLinLoc. To study the results quality, we compare origin time and source location to the OVPF manual catalog as well as a catalog resulting from template matching and double-difference relocation. In particular, we focus on pre- and syn-eruptive time-periods for multiple eruptions since 2014 in order to investigate the effect of elevated seismicity rate and eruptive tremor on the performance of the workflow. We also assess to what extent the quality of the resulting automatic locations are sufficient to provide an indication of the future eruption site without expert manual input.Applying this approach allows us to improve the monitoring of the seismicity at Piton de la Fournaise volcano. A work in progress is to implement the same approach over the entire island of La Réunion, which will enable the monitoring of other active areas in the region.
The mid-crustal low-velocity zones in Iceland revealed by multimodal surface wave
Authors: Zhang Sen , Chen Xiaofei
Published: March 2024

The evolution of the Icelandic crust has been significantly influenced by magmatism associated with the Icelandic hotspot and the Mid-Atlantic Ridge. The spreading mid-ocean ridge and fissure swarms create favorable conditions for magma migration, feeding active volcanic activities on the surface. Previous receiver function studies have reported the mid-crustal low-velocity zone (MCLVZ) as a crucial characteristic. However, it is absent in the previous model representing the overall features of Iceland. Recently, the frequency-Bessel transform method (F-J method) has been proposed, enabling the effective extraction of multi-mode dispersion curves from ambient noise data. We collect continuous seismic data from the HOTSPOT network in Iceland for 2 years, as well as other supplementary data, covering the main regions of Iceland. Using the F-J method, we extract multi-mode dispersion curves of 0.02-0.4 Hz. Subsequently, we obtain an Icelandic average Vs model, including an MCLVZ with an amplitude of 3%. Moreover, through the analysis of local region data, we identify MCLVZs in the western fjords and the central volcanic zone of Iceland. Our results supplement the previously lacking MCLVZ feature in the Icelandic average structure, suggesting the presence of MCLVZs in both volcanic and non-volcanic regions of Iceland. The elevated temperature and partial melting associated with the volcanic activity may be not the sole reasons for MCLVZs. Further research on the distribution of MCLVZs in Iceland is needed in the future.
Quantitative reconstruction of a single super rainstorm using daily resolved δ18O of land snail shell
Authors: Wang Guozhen , Dong Jibao , Yan Hong
Published: March 2024

A “once-in-a-millennium” super rainstorm battered Zhengzhou, central China, from 07/17/2021 to 07/22/2021 (named “7.20” Zhengzhou super rainstorm). It killed 398 people and caused billions of dollars in damage. ​A pressing question, however, is whether rainstorms of this intensity can be effectively documented by geological archives to understand better their historical variabilities beyond the scope of meteorological data. Here, four land snail shells (Cathaica fasciola) were collected from Zhengzhou in 2021, and weekly to daily resolved snail shell δ18O records from June to September of 2021 were obtained by gas-source mass spectrometry (GSMS) and secondary ion mass spectrometry (SIMS). The daily resolved records show a dramatic negative shift between 06/18/2021 and 09/18/2021, which has been attributed to is related to the “7.20” Zhengzhou super rainstorm. Moreover, the measured amplitude of the shell δ18O shift caused by the “7.20” Zhengzhou super rainstorm is consistent with the theoretical value estimated from the flux balance model and local instrumental data within the error range. Our results suggest that the ultra-high resolution δ18O of land snail shells have the potential to reconstruct local synoptic scale super rainstorm events quantitatively. And the proposed “best practice” of current work indicated that fossil snail shells in sedimentary strata can be valuable material for investigating the historical variability of local super rainstorms under different climate background conditions.
Integrative Analysis of Electrical Conductivity and Hydraulic Properties in Assessing Shallow Slope Stability
Authors: Yang Ya-Sin , Yeh Hsin-Fu , Ke Chien-Chung , Wei Lun-Wei , Chen Nai-Chin
Published: March 2024

This study integrated hydrological surveys with geophysical monitoring methods to obtain the geotechnical insights related to shallow landslides. The varied and complex conditions in subsurface pose difficulties in linking geophysical monitoring data to soil engineering properties. Therefore, we investigated the relationship between hydrological response and slope movement using real-time soil water and electrical conductivity data and displacement monitoring records. By integrating the relationship with the soil water characteristic curve (SWCC) and soil stress characteristic curves (SSCC) established from laboratory tests, we established specific curves that correlate electrical conductivity with soil water and stress. We also extended unsaturated soil shear strength model to relate the matric suction and electrical conductivity. We adopted finite element hydrodynamical model HYDRUS 2D and Slope Cube Module to assess the slope stability of shallow landslides triggered by rainfall. The local factor of safety obtained from numerical simulations were compared with the estimated shear strength values. The results showed that the changes in the shear strength estimated from the electrical conductivity is consistent with that of the local safety factor obtained from numerical simulations. This revealed that the shear strength model with electrical conductivity as a variable can reasonably evaluate slope stability, and is also suitable for analysis related to the hydraulic properties of unsaturated soils. This study can provide guidance for future field monitoring works and serve as a basis for shallow landslide early warning and slope stability assessment.
Importance of mantle serpentinite carbonation in bending faults for the deep carbon cycle
Authors: Huang Yongsheng , Okumura Satoshi , Matsumoto Kazuhisa , Takahashi Naoko , Tang Hong , Wu Guoji , Tsujimor Tatsumi , Nakamura Michihiko , Okamoto Atsushi , Li Yuan
Published: March 2024

Serpentinite carbonation contributes to the deep carbon (C) cycle. Recently, geophysical and numerical studies have identified considerable hydrothermal alterations in deep bending faults beneath outer-rise regions, implying potentially significant C storage in the slab mantle. However, quantitative determination of C uptake in outer-rise regions is lacking. Here, we experimentally constrained the serpentinite carbonation in H2O–CO2–NaCl fluids under bending fault conditions to estimate C uptake in the slab mantle. We found that serpentinite carbonation produced talc and magnesite along the serpentinite surface. The porous reaction zones (49.2% porosity) promoted the progress of the carbonation reaction through a continuous supply of CO2-bearing fluids to the reaction front. Strikingly, NaCl effectively decreased the serpentinite carbonation efficiency, particularly at low salinities (< 5.0 wt%), which is likely attributed to the reduction in H2O and CO2 activities (aH2O and aCO2) and transport rate of reactants, the change in pH of fluids, and the enhancement of magnesite solubility. We fitted an empirical equation for the reaction rate of serpentinite carbonation in bending faults and found that this reaction could contribute to a flux of 25–100 Mt C/yr in subduction zones. Our results shed new light on the deep C cycle and the serpentinite carbonation in environments with high salinities.
Criteria for selection of technology to exploit groundwater in water scare area in Vietnam
Authors: Trieu Duc Huy , Bui Du Duong , Tong Ngoc Thanh , Nguyen Quang Huy , Pham Van Hung , Pham Ba Quyen
Published: March 2024

The solutions for water extraction in the high mountains of the North commonly used are rainwater storage, dug wells, drilled wells, springs, and hanging lakes, etc. These solutions have basically met the water needs of the people. However, many water supply works operate inefficiently and operate inflexibly. In this study, 19 criteria belonging to 4 groups: a group of criteria on water resources; a group of criteria on economic and technical; a group of criteria on the social and a group of criteria on the environment have been established to select technologies for exploiting water sources suitable for high mountains and water scarcity to ensure long-term and efficient operation of the project. GIS approach was used, and criteria were integrated using Analytical Hierarchy Process (AHP) method (Saaty, 1980) to select suitable water resources extraction technology with high mountains and water scarcity. The research results show that the evaluation criteria to determine the area to apply technological solutions for sustainable exploitation of suitable water sources and the weights of the established criteria ensure a consistent ratio (CR< 10%) according to the hierarchical analysis method.
Sardinia Salty Pond area for CAL/VAL activities for supporting hyperspectral orbiting mission
Authors: Musacchio Massimo , Silvestri Malvina , Melis Titi , Rabuffi Federico , Casu Marco , Buongiorno Maria Fabrizia
Published: March 2024

A comparative analysis was conducted between the data acquired by ASI-PRISMA (Agenzia Spaziale Italiana-PRecursore IperSpet-trale della Missione Applicativa) and DLR-EnMAP (German Aerospace Center - Environmental Mapping and Analysis Program), along with field spectrometer measurements. The chosen test site, situated at the 'Sale’e Porcus' pond in Western Sardinia, Italy, exhibits notable homogeneity, rendering it an ideal location for calibration purposes. The two agencies, ASI and DLR, acquired three remote sensing data acquisitions from July 14th(DLR-EnMAP), 15th (ASI-PRISMA) and 22nd (DLR-EnMAP) 2023. On the data acquired on July 22nd, DLR-EnMAP showed an overestimation of radiance in the VNIR region compared to both ASI-PRISMA (15th July) and the DLR-EnMAP data (14th July). However, all datasets closely align up to 2500 nm across all the considered days. Despite a slight time acquisition difference of 8 days, the relative mean difference between reflectance values estimated by ASI-PRISMA and DLR-EnMAP on the test area is approximately 5%. The maximum relative difference occurs at the spectral range's beginning and end, reaching around 10%. The study delves into the relationship between the averaged ground truth reflectance values characterizing the test site and the reflectance values derived from official catalogues. FieldSpec measurements validate the quality of reflectance estimations for both ASI-PRISMA and DLR-EnMAP.
Synthetic Aperture Radar SLC data compression using Mean-Scale Hyperprior architecture
Authors: Léonard Cédric
Published: March 2024

Synthetic Aperture Radar (SAR) images are becoming increasingly important in a variety of remote sensing applications, leading to new missions with higher resolution and coverage, ultimately resulting in an ever-increasing volume of data. This burden on SAR data storage and transmission has established a serious interest in developing compression methods that can obtain higher compression ratios, while keeping complex SAR image quality to an acceptable level. In computer vision, neural network-based RGB image compression has exceeded traditional methods such as JPEG, JPEG2000 or BPG. The Mean-Scale Hyperprior network [1] is an auto-encoder based architecture exploiting the probabilistic structure in the latents to improve compression performance. Auto-encoders are architectures particularly suited for the inherent rate-distortion trade-off of data compression. They also offer an intuitive solution to the on-board image compression problem, as demonstrate for the Φ-Sat-2 mission [2].In this work, we explore efficient SAR image compression, in this regard, we adapt the Mean-Scale Hyperprior architecture to SAR data. We use Sentinel-1 IW mode VV polarization SLC images to build a dataset of diverse scenes: urban areas, forests, mountains and water bodies in dry as well as snow/ice conditions. The central idea being to create an open-source and general dataset of SAR images, in order to compare the performance of the studied architecture with traditional codecs and baseline models, such as the work in [3]. We will experiment with latent sizes, patch size as well as different SAR data representations for the network.References  [1] D. Minnen, J. Ball ́e, and G. D. Toderici, “Joint Autoregressive and Hierarchical Priors for Learned Image Compression,” in Advances in Neural Information Processing Systems, vol. 31, Curran Associates, Inc., 2018.  [2] G. Guerrisi, F. D. Frate, and G. Schiavon, “Artificial Intelligence Based On-Board Image Compression for the Φ-Sat-2 Mission,” IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, vol. 16, pp. 8063–8075, 2023.  [3] C. Fu, B. Du, and L. Zhang, “SAR Image Compression Based on Multi-Resblock and Global Context,” IEEE Geoscience and Remote Sensing Letters, vol. 20, pp. 1–5, 2023.
SeisPolar: Seismic Wave Polarity Module for the SeisBlue Deep Learning Seismology Platform
Authors: Chang I-Hsin , Huang Chun-Ming , Kuo-Chen Hao
Published: March 2024

Responding to challenges from increasing seismic data, our study leverages deep learning to enhance seismic data processing's automation and efficiency. Recognizing Taiwan's unique geological structure, we have developed deep learning models using data from dense seismic arrays since 2018. We have integrated the Transformer model with GAN training techniques for phase picking. Our latest system, SeisBlue, has evolved from phase picking and earthquake location to include magnitude and focal mechanism estimation, primarily using SeisPolar, a CNN model for P-wave polarity classification, crucial for focal mechanism analysis. Additionally, our redesign of the seismic monitoring process emphasizes data pipelines and integrates software engineering technologies, including hardware, system environment, database, data pipelines, model version control, task monitoring, data visualization, and Web UI interaction. The model shows high proficiency in identifying P-wave polarity and deciphering focal mechanisms, with an accuracy of 85%, and precision and recall rates for three categories [positive, negative, undecidable] at [87%, 77%, 53%] and [84%, 80%, 54%], respectively. It notably achieves about 70% Kagan angle under 40 degrees for focal mechanism analysis. This semi-automated workflow, from data processing to phase picking, earthquake location, magnitude determination, focal mechanism estimation and Web UI, significantly boosts seismic monitoring's efficiency and accuracy. It facilitates quicker and more meaningful engagement for researchers in subsequent studies, marking a notable advancement in seismic monitoring and deep learning application.
Links between heat waves, drought, and atmospheric circulation in Central Europe
Authors: Bešťáková Zuzana , Lhotka Ondřej , Stryhal Jan , Kyselý Jan
Published: March 2024

Heat waves and drought are phenomena associated with large negative impacts on society and environment. Their common features include increasing frequency and intensity in recent decades in many regions of Europe, as well as interconnectedness of the factors that contribute to their development. In this study, we evaluate links between heat waves and drought in Central Europe using E-OBS data and ERA-5 reanalysis in the 1979–2022 period. Heat waves are classified according to their 3-dimensional structure of positive temperature anomalies into near-surface, lower-tropospheric, higher-tropospheric, and omnipresent types. We show that the associations to soil moisture conditions and development of flash drought (based on the daily climatic water balance index) differ for the individual heat wave types; the links are most pronounced for near-surface heat waves, illustrating the compound nature of the heat-drought events. We also employ the Jenkinson–Collison classification to identify circulation types with significantly increased frequency during periods of heat waves and droughts, and study changes in their occurrence. The analysis contributes to better understanding of the interrelationships between drought, heat waves, atmospheric circulation and other driving mechanisms.
West African operational daily solar forecast errors and their links with meteorological conditions
Authors: Anquetin Sandrine , Clauzel Léo , Lavaysse Christophe , Tremoy Guillaume , Raynaud Damien
Published: March 2024

With its commitment to reduce greenhouse gas emissions and harnessing the potential of renewable energy, the West African region is at the forefront of global environmental challenges. This work focuses on the specific aspect of solar energy, which holds significant promise in the region. High quality solar energy forecasts are necessary for solar plants and power systems management, while they remain poorly developed in this region, in particular because of the specificities of the West African climate. We evaluate the errors in Global Horizontal Irradiance (GHI) operational forecast models for two Sahelian solar power plants, Zagtouli in Burkina Faso and Sococim in Senegal, and investigate their links with local meteorological conditions, with a specific focus on clouds and dust aerosols.This work begins by assessing aerosol products and our results support the use of the CAMS reanalysis for the assessment of Aerosol Optical Depth (AOD), particularly with respect to dust aerosols. We then assess the performance of three operational GHI forecast products: the Global Forecast System (GFS, NCEP/NOAA), the Integrated Forecast System (IFS, ECMWF), and SteadyMet (SM), developed by French company Steadysun, which is computed from the previously mentioned Numerical Weather Prediction (NWP) model outputs. The analysis reveals that IFS and SM outperform GFS in terms of forecast accuracy, with SM showing a slight advantage due to its probabilistic nature, which provides valuable information on forecast uncertainty.Closer examination reveals a significant relationship between GHI forecast errors and local meteorological characteristics. These errors are more pronounced during the wet season, primarily attributed to cloud occurrence. Dust events are found to play a secondary role, particularly during the dry season. Correlation analyses underline the main link between forecast errors and cloudiness, while co-occurrence analyses highlight the fact that dust aerosol loading is a secondary factor in forecast errors for the GHI directly or for cloud representation (aerosol-cloud interaction).
Flow-topography interaction over gravelly sand beds and the implications for transport of submarine groundwater discharge
Authors: Klettke Helena , Kandler Leonie , Grundmann Sven , Brede Martin
Published: March 2024

Submarine groundwater discharge is an important pathway of various nutrients and solutes from the land to the ocean. The groundwater discharging across the seabed interface is exposed to the highly dynamic conditions of the coastal ocean. The flow-topography interaction in the benthic boundary layer defines these dynamics and affects how the discharged groundwater is transported and mixed within the water column. Additionally, the flow-topography interaction can also drive convection in the seabed that can enhance fluxes across the seabed interface. To investigate these effects, laboratory experiments are conducted, where waves are generated over gravelly sand beds. In these types of beds, gravel protrudes from the seabed. The protruding part is altered to change its size and effective slope, to quantify their respective impact on the flow conditions. Additionally, water with a fluorescent dye seeps through the seabed, resembling groundwater discharge. A coupled PIV-LIF approach (Particle Image Velocimetry, Laser Induced Fluorescence) is used to measure the velocity field and the concentration of discharged water in the water column simultaneously. Both quantities are then correlated, which gives the turbulent Reynolds flux. This approach grants insights on the distribution, transport, and mixing of discharged water within the water column. Both, the seabed geometry and the wave scenario, significantly influence the turbulent flux. The results show different processes, such as wave pumping and separated vortex pumping, which drive convection in the seabed and alter the discharge rates. This leads to different concentrations of discharged water being measured in the water column, depending on the boundary conditions. While the outcome of these processes can be visualized and quantified in the water column from experimental data, complimentary surface-subsurface modeling holds the potential of additionally resolving the flow field within the seabed and expanding the investigated two-dimensional region to a three-dimensional domain. 
Combining orbital tuning and direct dating approaches to age-depth model development for Chew Bahir, Ethiopia
Authors: Trauth Martin H. , Fischer Markus L. , Foerster Verena , Marwan Norbert , Roberts Helen M. , Schaebitz Frank
Published: March 2024

The directly dated RRMarch2021 age model (Roberts et al., Quaternary Science Reviews, 2021) for the ~290 m long composite core from Chew Bahir, southern Ethiopia, has provided a valuable chronology for long-term climate changes in northeastern Africa. However, the age model has limitations on shorter time scales (less than 1–2 precession cycles), especially in the time range
Remote Sensing Observations of Sulfides and Sulfates for the Geologic Mapping of the Extreme Acidic Environment of Rio Tinto, Spain
Authors: Panza Giacomo , Frigeri Alessandro , Skinner James , Gómez Felipe , Cavalazzi Barbara , Rocchini Duccio , Altieri Francesca , De Sanctis Maria Cristina
Published: March 2024

After its long reputation as an extremely polluted water river and anthropogenic mining waste dump, studies support Rio Tinto (southern Spain, Iberian Pyrite Belt) to be an extremely acidic environment where life relentlessly thrived long before human history. It has become clear that in this extreme environment, there are strong relationships between living and nonliving components at the microscale, resulting in the formation of micro-niche-based ecosystems. The site has therefore become a terrestrial analog of first interest for astrobiological and planetary science studies in terms of the search for life on Mars. The acidic environment is the product of the chemolithotrophic activity of microorganisms aggressively targeting sulfides (pyrite, chalcopyrite), here abundant, causing the leaching of iron and sulfur. This contributes to the formation of a variety of minerals, mainly gypsum, jarosite, goethite, and hematite, all of which have been detected on the Red Planet. Identifying and discretizing sulfides and iron-bearing sulfates from orbit and landed missions has been a relevant method for searching for life on Mars, notably distinguished by its iron-sulfur-rich composition. Similar mapping sulfide and sulfate distributions on easy-to-access terrestrial analog are critical to improving our ability to interpret data from other worlds and contextualize astrobiological observations.  In this work, we present the spectroscopic analysis of remote sensing data over Rio Tinto, focusing on mapping the distribution of sulfides and sulfates as a proxy for the presence of biosignatures. We have studied multi- and hyper-spectral data from orbital and airborne spectrometers, cross-checking evidence from different datasets.   The results of our work have been cartographically formatted and served to support the geologic mapping fieldwork campaign held at the Rio Tinto in November 2023.
Complex Frictional Behavior of Clay and Implications for Slow Slip 
Authors: Volpe Giuseppe , Collettini Cristiano , Taddeucci Jacopo , Marone Chris , Pozzi Giacomo
Published: March 2024

The shallowest region of subduction megathrust accommodates deformation by a spectrum of seismic modes including continuous aseismic creep and peculiar seismic phenomena as slow slip events. However, the mechanisms behind these phenomena remain enigmatic because they are not explained by conventional frictional models. This because the shallowest regions of subduction zones are characterized by unconsolidated, clay-rich lithologies that, nominally, cannot nucleate seismic events due to their frictionally weak and rate-strengthening attributes. Here we present laboratory friction experiments showing that clay-rich experimental faults with bulk rate strengthening behavior and low healing rate can contemporaneously creep and nucleate slow slip events. These instabilities are self-healing, slow ruptures propagating within a thin shear zone and driven by structural and stress heterogeneities. We propose that the bulk rate-strengthening frictional behavior promotes the observed long-term aseismic creep whereas local frictional mechanism causes slow rupture nucleation and propagation. Our results illustrate the complex behavior of clay-rich lithologies, providing a new paradigm for the interpretation of the genesis of slow slip as well as significant implications for seismic hazard.
Characteristics and Influencing Factors of Convective Boundary Layer Height on the Tibetan Plateau During Different Periods of the Summer Monsoon
Authors: Wang Chunxiao , Ma Yaoming , Han Cunbo , Zhang Yunshuai
Published: March 2024

The study of the atmospheric boundary layer (ABL) on the Tibetan Plateau (TP) is important to understand surface heat and moisture balances, as well as weather and climate change on the TP and surrounding areas. However, studies focusing on the ABL during different monsoon periods across the TP are limited. Here, we investigated the convective boundary layer height (CBLH) during the pre-monsoon, monsoon, and post-monsoon periods using radio sounding data at six research stations on and near the TP. During the pre-monsoon period, the CBLH of TP stations gradually decreased from south to north, peaking at 3444 m. During the monsoon period, there was a gradual decrease in CBLH from north to south, with a peak of 3393 m. Notably, stations heavily influenced by the monsoon (Shiquanhe, BJ, and QOMS stations) experienced declining CBLH as the monsoon advanced, while others saw an increase. During the post-monsoon period, the CBLH at Shiquanhe station, located on the western TP, was consistently highest, reaching a maximum of 3679 m. CBLH increased at Shiquanhe, BJ, and QOMS stations as the monsoon retreated but decreased at the remaining stations. Surface flux observations revealed that stations heavily impacted by the monsoon exhibited a minimal contribution ratio (CR) of sensible heat flux to convective boundary layer (CBL) development during the monsoon period. Furthermore, these monsoon-impacted stations exhibited the highest stability of the mid-lower atmosphere during the monsoon period, hindering CBL development.
The influence of extratropical cross-tropopause mixing on the correlation between ozone and sulfate aerosol in the lowermost stratosphere
Authors: Joppe Philipp , Schneider Johannes , Kaiser Katharina , Fischer Horst , Hoor Peter , Kunkel Daniel , Lachnitt Hans-Christoph , Marsing Andreas , Röder Lenard , Schlager Hans , Tomsche Laura , Voigt Christiane , Zahn Andreas , Borrmann Stephan
Published: March 2024

The composition of the upper troposphere/lower stratosphere region (UTLS) is influenced by long-range or regional transport in the troposphere and stratosphere, vertical transport within convective systems and warm conveyor belts, rapid turbulent mixing, as well as photochemical production or loss of species. This results in the formation of the extratropical transition layer, which has been defined by the vertical structure of CO profiles and studied by now mostly by means of trace gas correlations. Here, we extend the analysis to aerosol particles and derive the ozone to sulfate aerosol correlation in Central Europe from aircraft in-situ measurements during the CAFE-EU/BLUESKY mission in May and June 2020. During the campaign two research aircraft, i.e., DLR-HALO (High Altitude and Long Range Research Aircraft) and DLR-Falcon, were deployed covering an altitude range from the planetary boundary layer up to 14 km altitude and thus probing the UTLS during the COVID-19 period with significant reduced anthropogenic emissions. We operated a compact time-of-flight aerosol mass spectrometer (C-ToF-AMS) to measure the chemical composition of non-refractory aerosol particles in the size range from about 40 to 800 nm. In addition to the C-ToF-AMS data, we use trace gas measurements from both HALO and DLR-Falcon.In our study, we find a correlation between the ozone mixing ratio (O3) and the sulfate mass concentration in the lower stratosphere, between 10 and 14 km for all flights. The correlation is not constant with time but exhibits some variability over the two-week period of the campaign exceeding the background sulfate to ozone correlation. Especially during one flight, we observed enhanced mixing ratios of sulfate aerosol in the lowermost stratosphere, where the analysis of trace gases, such as CO, SO2, H2O, O3 and HNO3 show tropospheric influence during this time. Also, back trajectories indicate, that no recent mixing with tropospheric air occurred within the last 10 days. In addition, we analyzed satellite SO2 retrievals from TROPOMI for volcanic plumes and eruptions. These satellite observations show enhanced volcanic activities in April 2020 on Kamchatka, Russia, with at least one explosive eruption of the Sheveluch volcano reaching the tropopause region and some minor eruptions of different volcanoes into the free troposphere. From these findings, we conclude that gas-to-particle conversion of volcanic SO2 leads to the observed enhanced sulfate aerosol mixing ratios.
Global Ionospheric Responses in Both Hemispheres during the 2015 St. Patrick's Day Storm
Authors: Malvi Bhupendra , Purohit Pramod
Published: March 2024

On St. Patrick's Day, March 17, 2015, the first historical intense geomagnetic storm (Dst < −200 nT) of the 24th solar cycle occurred. This storm caused complex effects around the globe. Geomagnetic storms are a concern for society, especially the strongest storms and how they affect satellite communications, navigations and power grids. Using Global Positioning System (GPS) data to compute the Total Electron Content (TEC) of the Earth's ionosphere is one of the most common methods used to investigate perturbations in the ionosphere. GPS TEC variations may reveal ionospheric anomalies, which might endanger the continuity and availability of GPS performance metrics. Thus, the ionospheric consequences of geomagnetic storms have been researched intensively for decades but are still not fully understood. This study investigates the ionospheric behaviour during an intense geomagnetic storm that occurred from 14 - 24 March 2015. In particular, we used geomagnetic indices and GPS TEC data from various IGS stations all over the world to give a comprehensive analysis of how the ionospheric total electron content changes in both the northern and southern hemispheres at different latitude and longitude stations.
Phloem transport of tall tree and its diurnal variations
Authors: Dannoura Masako , Takanashi Satoru , Kamakura Mai , Wang Shitephen , Tanabe Tomoko , Fujii Rei , Mochidome Takumi , Paul Sumonta Kumar , Schaefer Holger , Kosugi Yoshiko , Epron Daniel
Published: March 2024

To understand diurnal variations in phloem transport in tall trees, 13C-CO2 pulse labelling experiments were conducted on a 20.4 m tall Chamaecyparis obtusa tree. 13C-CO2 labelling were carried out in the morning and afternoon at close dates in autumn of 2020 and 2022, and in the isotope composition of stem respired CO2 was measured at four heights (17.0, 13.5, 6.23, 1.85 m) along the stem using a carbon stable isotope ratio analyzer (Picarro G2131-i). Small bark samples were taken to observe the anatomy of the phloem and measure the sieve tube radius on the labelled tree.The rate of phloem transport at different positions along the stem differed from day to day. The phloem transport rate was inferred to be low or zero in sunny condition and high (0.15-0.24 m h-1) in cloudy weather and at night. This is consistent with the fact that the sink-source hydrostatic pressure difference (driving force) was higher at night than on sunny days. Daytime and nighttime turgor was calculated using data on midday and predawn water potential, osmotic potential, and gravity potential from similarly sized trees from same site. Using the anatomy data, the maximum phloem velocity in the night was calculated as 0.28 (m h-1).Both approaches revealed that phloem transport of carbohydrates in tall cypress trees took five or six days to reach the roots after they were produced by leaf photosynthesis, and that the rate of phloem transport increased and decreased overtime during transportation depending on weather conditions and day-night alternation.
Precisely dated climate records challenge the Southern Hemisphere glacial aridity paradigm
Authors: Weij Rieneke , Sniderman Kale , Woodhead Jon , Hellstrom John , Brown Josephine , Drysdale Russell , Reed Liz , Bourne Steven , Gordon Jay
Published: March 2024

While global changes in temperature during the last 1.5 Ma are well constrained, the terrestrial response to these changes is less understood, particularly in the Southern Hemisphere. Late Pleistocene ice-age climates are routinely characterised as having imposed moisture-stress on low/mid-latitude ecosystems. This idea is largely based on fossil pollen evidence for widespread, low-biomass glacial vegetation, interpreted as indicating climatic dryness. However, woody plant growth is inhibited under low atmospheric CO2, so understanding glacial environments requires the development of new palaeoclimate indicators that are independent of vegetation. Here, we present two new, well-dated speleothem records from subtropical, southern Australia, both spanning the last three glacial-interglacial cycles. We show that, contrary to expectations, over the past ~350 ka, peaks in southern Australian climatic moisture availability were largely confined to glacial periods, including the last glacial maximum, while warm interglacials were relatively dry. By measuring the timing of speleothem growth in the Southern Hemisphere subtropics, which today has a predominantly negative annual moisture balance, we developed a record of climatic moisture availability that is independent of vegetation and extends through multiple glacial-interglacial cycles. Our results demonstrate that a cool-moist response is consistent across the austral subtropics, and in part may result from reduced evaporation under cool glacial temperatures. Insofar as cold glacial environments in the Southern Hemisphere subtropics have been portrayed as uniformly arid, our findings suggest that their characterisation as evolutionary or physiological obstacles to movement and expansion of animal, plant and, potentially, human populations should be reconsidered.
Estimating near-surface reduction in shear-strength on hillslopes caused by strong ground shaking
Authors: Tanyas Hakan , Xi Chuanjie , Lombardo Luigi , He Kun , Hu Xiewen , Jibson Randall
Published: March 2024

The weakening of hillslopes during strong earthquakes increases landsliding rates in post-seismic periods. However, very few studies have addressed the amount of coseismic reduction in shear strength of hillslope materials. This makes estimation of post-seismic landslide susceptibility challenging. Here we propose a method to quantify the maximum shear-strength reduction expected on seismically disturbed hillslopes. We focus on a subset of the area affected by the 2008 Mw 7.9 Wenchuan, China earthquake. We combine physical and data-driven modeling approaches. First, we back-analyze shear-strength reduction at locations where post-seismic landslides occurred. Second, we regress the estimated shear-strength reduction against peak ground acceleration, local relief, and topographic position index to extrapolate the shear-strength reduction over the entire study area. Our results show a maximum of 60%-75% reduction in near-surface shear strength over a peak ground acceleration range of 0.5-0.9 g. Reduction percentages can be generalized using a data-driven model.
Mechanistic Insights into the Selectivity of Sulfidated Zero-Valent Iron Materials in Chlorinated Ethenes Removal: A DFT Study
Authors: Brumovsky Miroslav , Tunega Daniel
Published: March 2024

Chlorinated ethenes (CEs), such as perchloroethene (PCE) and trichloroethene (TCE), are pervasive groundwater contaminants. Owing to their toxic properties, there is a considerable effort for their remediation. In this context, in situ CE chemical reduction using zero-valent iron (ZVI) materials represents a promising strategy. However, the intrinsic low electron selectivity of pristine ZVI often results in its rapid surface corrosion and passivation in subsurface environments. In the last years, sulfidation has emerged as an effective means to enhance the reactive lifetime of ZVI. Despite the efficiency of sulfidated ZVI (S-ZVI) in dechlorinating TCE and trans-1,2-dichloroethene (trans-DCE), a notably lower reactivity has been typically observed for PCE and cis-1,2-dichloroethene (cis-DCE). The mechanisms governing the variable reactivity of S-ZVI with different CEs remain poorly understood.To shed more light on the mechanisms controlling S-ZVI selectivity, we calculated the dechlorination barriers of various CEs at multiple S-ZVI surface models using density functional theory (DFT). Specifically, we focused on the electron transfer-controlled β-elimination reactions, identified as the predominant pathway for CE dechlorination with S-ZVI. Reactions of PCE, TCE, and both cis- and trans-DCE isomers were investigated at different S-ZVI surface sites, including surfaces with varying sulfur coverage. Our calculations revealed that CE dechlorination reactions are both kinetically and thermodynamically more favorable at Fe sites compared to S sites. This finding indicates that the overall promoting effect of ZVI sulfidation on CE degradation is indirect, primarily involving the protection of the ZVI surface from corrosion in water. Sulfur coverage was identified to significantly influence the S-ZVI selectivity for individual CEs. Under low S coverage, the reactivity of Fe sites followed the order trans-DCE ≈ TCE > cis-DCE > PCE, with PCE degradation hindered by steric effects from nearby S atoms. Conversely, at high S coverage, Fe sites were sterically hindered for all CEs, and reactivity was controlled by S sites. In this scenario, energy barriers correlated with the energy of the lowest unoccupied molecular orbital (ELUMO) of CEs in the order PCE < TCE < DCE isomers. These findings demonstrate that the experimentally observed trends in S-ZVI selectivity for individual CEs can be explained by the interplay between the affinity of CEs for electron transfer and steric effects of S atoms at the ZVI surface. AcknowledgmentsThis work was funded by the Austrian Science Fund (FWF), project M 2892-N. The Vienna Scientific Cluster (project no. 70544) is gratefully acknowledged for providing computational resources.
A Time-Space varying Distributed Unit Hydrograph (TS-DUH) for lare-scale operative flash flood forecast
Authors: Hu Ying , Wu Huan , Chen Weitian , Li Chaoqun , Wu Wei , Huang Zequn , Jiang Lulu , Huang Zhijun
Published: March 2024

Increasing threats of flash flood call for effective and operative ways to offer accurate forecasting and warning. In this study, a Time-Space varying Distributed Unit Hydrograph (TS-DUH) based on publicly-available-only data is proposed for efficient flash flood forecasting. As in the traditional spatially distributed unit hydrograph (SDUH) method, TS-DUH initially estimates the runoff travel time (and flow velocity) from each location within a catchment to the outlet based on topographic and hydroclimate characteristics. However, the delineation of the runoff-drainage process is further adjusted by considering the heterogeneous and dynamic runoff contribution caused by rainfall and soil moisture variations. The excess rainfall is estimated by the widely used Global Flood Monitoring System (GFMS) which provides long-term (2000-present) well-archived and real-time operative global runoff datasets from a state-of-the-art DRIVE model (DRIVE-Runoff). An alternative excess rainfall input is taken from the Soil Conservation Service's curve number method (CN-Runoff). The performance of the TS-GUH method is evaluated using 6,324 flash flood events of 281 small-to-medium-sized catchments in the CONUS, with 1,686 events used for calibration. The validation results show that using DRIVE-Runoff is better than CN-Runoff, 99% and 71% of events have KGE values greater than 0 and 0.5, respectively, with a median KGE value of 0.6 and the probability of detection (POD) of flood events 0.9. More importantly, using near real-time satellite rainfall-driven DRIVE-Runoff, long-term flow simulation (2003-2020) without calibration at 803 gauges shows better performance of TS-DUH than the original GFMS, with a median KGE improvement of 0.15. This combined UH and numerical hydrological model approach showed great potential for flash food monitoring and forecasting at regional or global scales.