bluuebunny/crossref_metadata_2025 huggingface dataset:
Weathering effects on microplastic production in fishing rope hauler operations:  mechanical abrasion 
Authors: Song Young Kyoung , Kim U-Seong , Kim Tae-Hoon
Published: March 2024

While land-basd sources of plastic pollution have garnered increasing attention in recent years, ocean-based sources have been less thoroughly examined. The objective of this study was to quantify and characterize the production of microplastics on the surface of fishing ropes during the operation of a hauler on a fishing boat. The simulation of the fishing process (operating the hauler) was conducted in two phases to assess quantification, size distribution, and shapes of particles produced from the fishing ropes due to mechanical abrasion with the hauler.Initially, we simulated the fishing operation using the hauler with varying weights at 0, 5, 10, 15, and 20 kg (weight-varied hauler simulation, WVHS). Subsequently, we simulated the fishing operation using the hauler according to the frequency of hauler operation (0, 5, 10, 15, and 20 times) with weights of 5kg and 50kg (frequency-varied hauler simulation, FVHS). All fragmented particles were identified using a FTIR microscope (Nicolet iN10 MX; Thermo Fisher Scientific) equipped with a linear array detector, employing 25 μm steps over one section (~12 × 12 mm) in reflection mode.In the results of WVHS experiment, the abundance of fragmented particles larger than 10 mm on the surface of the PP rope increased with the weight due to mechanical abrasion. The observed values were 31±1.2 particles/m (5kg), 52±21 particles/m (20kg), 69±44 particles/m (35kg), and 77±5.7 particles/m (50kg) when lifting each weight using the hauler. The estimated regression equation was y=1.383x+15.538 (F=4.585, p=0.001). In the FVHS experiment, the abundance of produced particles peaked at 10 times and subsequently sustained a steady state in particle abundance for the 5 kg weight. For the 50 kg weight, the peak occurred at 5 times of hauler simulation, with subsequent reductions and a steady state in particle abundance. Our research offers essential information to estimate the microplastic production on fishing ropes during hauler operating, providing valuable insights into the impact of fishing activities on microplastic production in marine environments.
Resisting the unknown: Enhancing resistivity imaging of the crust through a multidisciplinary approach from µ- to km-scale at the DIVE DT-1B drill site
Authors: Tholen Sören , Toy Virginia , Hawemann Friedrich , Mansouri Hadis
Published: March 2024

Geophysical methods based on the conductivity of electrical currents through the subsurface (IP, ERT, magnetotellurics) are commonly used to identify mineral deposits or aquifers, for which large conductivity contrasts exist between host rock and target. These methods may also provide insights about tectonic processes, such as when rock masses contain partial melt, or are affected by active deformation. However, further advances in electrical imaging of rocks at depth are hindered by the lack of understanding of the relative contributions of paragenesis, fabric, and active processes to electrical conductivity. The ICDP project DIVE (Drilling the Ivrea-Verbano ZonE) provides a unique opportunity to evaluate these parameters by combining samples and measurements from up to ~580 m depth with a wide range of geophysical surface surveys.The DT‑1B drill core comprises lower crustal rocks consisting mostly of metapelite and amphibolite with embedded pegmatitic lenses. We took 25 samples from these main lithologies that cover the major variations in fabric (e.g., foliation strength, continuity and style, grain size), as well as intervals rich in micro fractures, hydrous alteration, or highly conductive phases (graphite, sulfide). We focus on two main research questions: (1) How do aspects of rock fabrics such as style and strength of foliation or mineral content and the connectivity of conductive phases affect the electrical properties, and (2) can these micro-scale, fabric-induced electrical properties be extrapolated to larger scales?Fabric analysis and quantification of mineralogy are carried out at thin-section scale by optical and electron microscopy (EDX, EBSD). Computed tomography (CT) performed on small cylinders drilled from the same samples allows the microstructural data to be extended into the third dimension. The CT ably reveals the elongation and alignment of sulfides, the style, and continuity of the foliation which is defined by biotite, and in places graphite- or sulfide-decorated fracture systems. Measurement of electrical properties of the same cylinders under various fluid saturation conditions and a wide frequency range completes the comprehensive database, enabling us to detect and model electrical pathways in the lower crust.To scale from the micro to the macro scale, these results will be compared to the data from electrical surveys carried out around the DT-1B drill hole. Results will expand the applicability of resistivity imaging for a wide range of future, structural applications.
Calibrating stable Sr isotope proxy for paleo-oceanographic studies: Insights from δ88/86Sr variability in modern and Holocene coastal marine system in South Australia 
Authors: Farkas Juraj , Shao Yuexiao , Mosley Luke , Tyler Jonathan , Tibby John , Eisenhauer Anton
Published: March 2024

Ocean water yields an integrated global signal of geological and biological processes operating on our planet, which in turn control the marine C cycle, oceanic alkalinity budget and atmospheric CO2 levels. Therefore, reconstructing the chemical and isotope composition of seawater and/or coastal waters through time represents one of the main research objectives of earth system evolution studies.Here we present stable and radiogenic Sr isotope variations (δ88/86Sr and 87Sr/86Sr) measured in waters and carbonates from modern and Holocene coastal marine system in South Australia (Coorong Lagoon/Murray River Estuary) that is connected to the Southern Ocean, thus exhibiting large gradients in water chemistry, salinity and carbonate saturation (Mosley et al. 2023; Shao et al. 2021). The studied hydrological system shows a large salinity range from brackish (70 psu) and oversaturated (SI ~1) waters. In contrast, the isotopically light and systematically lower stable Sr isotope signatures (< 0.35‰) are documented in brackish waters that are also undersaturated with respect to CaCO3 minerals (SI < 0). Overall, these results point to the primary control of carbonate dissolution versus precipitation phenomena, and thus CaCO3 saturation, on the δ88/86Sr proxy in the modern coastal marine system.Finally, we will also illustrate how a coupled δ88/86Sr and 87Sr/86Sr approach can be applied for paleo-salinity reconstructions of the coastal marine systems, such as the Coorong Lagoon, based on the Sr isotope analysis of recent and fossil carbonate archives (bivalve shells) recovered from local sediment cores (Shao, 2022). Briefly, available results and geochemical modeling of the Sr isotope data from Holocene fossil shells suggest that over the last ~2400 years the Coorong Lagoon become progressively more evaporitic, exhibiting a temporal shift from a purported brackish paleo-lagoon to the present-day hypersaline carbonate producing system.    References Farkas et al. (2024) Treatise on Geochemistry, Third Edition. Elsevier (Book Chapter 00086)Mosley et al. (2023) Marine Pollution Bulletin, 188, 1-16.  Shao (2022) PhD Thesis, University of Adelaide Shao et al. (2021) GCA, 293, 461-476.  
Holocene temperature changes in southeastern China reconstructed from stalagmite fluid inclusions
Authors: Liang Zeyuan , Zhang Haiwei , Tian Ye , Cheng Hai , Spöt Christoph , Cai Yanjun , Zhang Rui , Zong Baoyun , Ning Youfeng
Published: March 2024

The long-term trends of Holocene temperature obtained from reconstructions and simulations are inconsistent and have been controversial. Paleoclimate reconstructions suggest a gradual cooling after the Holocene climatic optimum, while model simulationss show continued warming. This is the long-standing Holocene conundrum. It is argued that some Holocene temperature reconstructions may be influenced by summer temperature bias. Therefore, finding proxy indicators less influenced by temperature seasonality is crucial in resolving the conundrum. Additionally, temperature reconstruction records in Southeast China are not yet comprehensive, the sensitivity of various proxies, uncertainties in chronology, and the uneven distribution of proxy records have led to significant differences in temperature reconstruction results. Stalagmites inside cave are in a relatively stable environment, and cave monitoring shows that the cave temperature is usually stable and represents the local annual mean temperature. Therefore, utilizing the water stable isotopes from stalagmite fluid inclusions can more accurately reconstruct local annual mean temperatures. This study used hydrogen and oxygen isotopes of three stalagmite samples (SN35, SN38, and SN42) from the Shennong Cave in Southeast China to reconstruct a temperature record for the Holocene (9 ka-0.8 ka). By employing a conversion function between calcite fluid inclusion water isotopes and annual mean temperature, we found the reconstructed cave temperature is ~19.1°C from 2-0.8 ka BP, consistent with the modern local annual mean temperature of 19.1°C, indicating these stalagmites could precisely record the local annual temperature changes. The reconstructed Holocene record shows a slight overall upward trend during the period of 9-0.8 ka BP, in agreement with model simulation results. The records also show a significant drop in temperature around 5.2 ka BP and a further abrupt change in temperature around 4.2ka BP, which may have had an important impact on the origin and decline of Liangzhu, a well-developed neolithic culture in the lower reaches of the Yangtze River.Our new record provides new evidence to resolve the Holocene temperature conundrum.
Chemical-Based Event-Stratigraphic Correlation along the Japan Trench by XRF-CS Chemical Fingerprint and Multivariate Statistics
Authors: Lin Jun-Ting , Huang Jyh-Jaan , Ikehara Ken , Strasser Michael , Hsu Ta-Wei , Su Chih-Chieh , Shao Yu-Hsun , Wu Yen-Hsi , Amano Astuko
Published: March 2024

Megathrust earthquakes in subduction zones, such as the AD 2011 Tohoku-oki earthquake, are known to generate turbidity currents that transport sediment into deep marine trenches, creating distinctive event deposits. These deposits are pivotal in submarine paleoseismology, which seeks to extend earthquake records and assess disaster potentials by meticulously analyzing the spatiotemporal distribution of these deposits through precise distinction and correlation. In our research, over 800 meters of sediment cores from 15 sites along the Japan Trench were collected during the International Ocean Discovery Program (IODP) Expedition 386, focusing on these event deposits to trace earthquake history. Utilizing X-ray Fluorescence Core Scanning (XRF-CS), we performed efficient and non-destructive high-resolution analysis of the chemical characteristics of these deposits. Our methodology integrates XRF-CS data with multivariate statistical techniques, such as Principal Component Analysis (PCA) and Cluster Analysis (CA). This integration enables us to objectively differentiate and correlate event deposits based on their unique chemical properties. Significant discoveries were made at Site M0083, where we detected variations in background sediments and event deposits associated with major historical earthquakes, including the AD 1454 Kyotoku and AD 869 Jogan events. These unique chemical fingerprints were also traced to adjacent trench-fill basins at sites M0089 and M0090, revealing consistent event-stratigraphic sequences across the basins and affirming the efficacy of our chemical-based correlation technique. In our ongoing analysis, we aim to explore the diverse chemical fingerprints of background sediments, turbidite bases, and turbidite tails. This investigation seeks to uncover potential spatial and stratigraphic provenance changes, and includes examining mineral and biogenic compositions, such as clay minerals and smear slides, to elucidate the reasons behind variations in chemical signals. Our findings underscore the effectiveness of combining chemical analysis with statistical methods for event-stratigraphic correlation. This novel approach not only sheds light on provenance changes but also helps establish a detailed spatiotemporal distribution framework for event deposits along the Japan Trench. Moreover, this integrated methodology could inform subsequent sampling strategies by objectively selecting sampling locations based on the chemostratigraphy framework. It also has the potential to be adapted to other research areas that require event-stratigraphic correlation and comprehensive spatiotemporal analysis.
The capability of deep learning model to predict atmospheric compositions across spatial and temporal domains
Authors: Han Weichao , He Tai-Long , Jiang Zhe , Wang Min , Jones Dylan , Miyazaki Kazuyuki , Shen Yanan
Published: March 2024

Machine learning (ML) techniques have been extensively applied in the field of atmospheric science. It provides an efficient way of integrating data and predicting atmospheric compositions. However, whether ML predictions can be extrapolated to different domains with significant spatial and temporal discrepancies is still unclear. Here we explore the answer to this question by presenting a comparative analysis of surface carbon monoxide (CO) and ozone (O3) predictions by integrating deep learning (DL) and chemical transport model (CTM) methods. The DL model trained with surface CO observations in China in 2015-2018 exhibited good spatial and temporal extrapolation capabilities, i.e., good surface daily CO predictions in China in 2019-2020 and over 10% independent observation stations in China in 2015-2020. The spatial and temporal extrapolation capabilities of DL model are further evaluated by predicting hourly surface O3 concentrations in China, the United States (US) and Europe in 2015-2022 with a DL model trained with surface O3 observations in China and the US in 2015-2018. Compared to baseline O3 simulations using GEOS-Chem (GC) model, our analysis exhibits mean biases of 2.6 and 4.8 µg/m3 with correlation coefficients of 0.94 and 0.93 (DL); and mean biases of 3.7 and 5.4 µg/m3 with correlation coefficients of 0.95 and 0.92 (GC) in Europe in 2015-2018 and 2019-2022, respectively. This analysis indicates the potential of DL to make reliable atmospheric composition predictions over spatial and temporal domains where a wealth of local observations for training is not available.
Non-stationary geostatistical modeling of daily rainfall over complex topography
Authors: Benoit Lionel , Lucas Matthew , Allard Denis , Giambelluca Thomas
Published: March 2024

In mountains, topography-atmosphere interactions generate orographic effects which make windward slopes usually wetter than leeward ones, and highlands wetter than lowlands. The transitions between wet and dry areas can occur within few kilometers, which creates strong horizontal gradients of rainfall statistics such as frequency of occurrence, daily mean accumulation, or extreme intensities. This spatial variability of rainfall statistics breaks the hypothesis of stationarity on which rely most geostatistical models that are used for the spatial analysis of rainfall data. Using stationary models to process non-stationary data can lead to a degraded performance in spatial prediction (e.g., mapping rainfall by interpolation of sparse rain gauge observations) and to unrealistic rainfall features in simulations (e.g., emulation of synthetic rain fields using a stochastic rainfall generator).  To overcome these limitations, we present in this work a fully non-stationary trans-Gaussian geostatistical model dedicated to the spatial analysis of daily rainfall over complex topography. This model allows not only for a non-stationary marginal distribution of daily rainfall accounting for rainfall intermittency and non-Gaussian intensity, but also for a non-stationary covariance structure of Matérn type that models the spatial dependencies.The model is tested for the Island of Hawai‘i (State of Hawaii, USA) where rainfall gradients are amongst the strongest on Earth and can reach 1000 mm.year-1/km. To make our model operable in practice, we designed a procedure to infer model parameters from rain gauge observations that are freely available in near-real-time on the Hawai‘i Climate Data Portal. Model assessment demonstrates good skills at reproducing the spatial variability of daily rainfall occurrence, intensity distribution and spatial dependencies.
GEMS ozone product evaluation using ozonesonde measurements during the ACCLIP campaign
Authors: Kim Joowan , Oh Subin , Bak Juseon , Koo Ja-Ho , Park Sang Seo , Lee Won-Jin
Published: March 2024

This study presents an comprehensive evaluation of Geostationary Environment Monitoring Spectrometer (GEMS) ozone products using daily ozonesonde data measured during the Asian Summer Monsoon Chemical and Climate Impact Project (ACCLIP). The analysis uses a total of 38 ozonesonde measurements along with atmospheric reanalysis to better understand ozone variability and circulation impacts during the Asian summer monsoon. It shows significant variability of tropospheric and lower stratospheric ozone related to convective activities associated with the Asian monsoon rainband and strong anticyclone in the upper troposphere and lower stratosphere (a.k.a. Tibet high). The comparison of the ozonesonde data and GEMS ozone products reveals GEMS’s capability to capture these variabilities, and also highlights its potential utility in the studies of chemical transport and regional-scale air quality in Asia.
Constraining a plant hydraulics-enabled land surface model with microwave radiometry: impact of temporal resolution
Authors: Konings Alexandra , Holtzman Natan , Wang Yujie , Wood Jeffrey , Frankenberg Christian
Published: March 2024

Vegetation water content (VWC) plays a key role in transpiration, plant mortality, and wildfire risk. Although land surface models now often contain plant hydraulics schemes, there are few direct VWC measurements to constrain these models at global scale. A potential solution to this data gap is passive microwave remote sensing, which is sensitive to temporal changes in VWC. Here, we test that approach by using synthetic microwave observations to constrain VWC and surface soil moisture within the Climate Modeling Alliance Land model. We further investigate the possible utility of sub-daily observations of VWC, which could be obtained through a satellite in geostationary orbit or combinations of multiple satellites. These high-temporal-resolution observations could allow for improved determination of ecosystem parameters, carbon and water fluxes, and subsurface hydraulics, relative to the currently available twice-daily sun-synchronous observational patterns that cannot single-handedly capture the two most informative times of the diurnal cycle (i.e. pre-dawn and mid-day). We find that incorporating observations at four different times in the diurnal cycle (such as could be available from two sun-synchronous satellites) provides a significantly better constraint on water and carbon fluxes than twice-daily observations do. For example, the root mean square error of projected evapotranspiration and gross primary productivity during drought periods was reduced by approximately 40%, when using four-times-daily relative to twice-daily observations. Adding hourly observations of the entire diurnal cycle did not further improve the inferred parameters and fluxes.
Vanadium Enrichments of Meta-Gabbroic Rocks in central part of the Menderes Massif (Türkiye): The Incremental Effect of Magmatism and Metamorphism in Highly Siderophile Environments
Authors: Sutcu Naside Merve , Doner Zeynep , Unluer Ali Tugcan , Kumral Mustafa
Published: March 2024

Especially in the context of renewable energy, vanadium (V) is an important component of energy storage technology. Gabbroic rocks in crustal environments may host a considerable amount of V-bearing minerals such as magnetite, and ilmenite. This study focuses on primary V occurrences in Precambrian-Cambrian aged meta-gabbroic rocks of the Alaşehir-Manisa area in the central part of the Menderes Massif (Türkiye). The primary purpose of the study is twofold; 1) to determine the V potentiality of meta-gabbro and 2) to reveal the enrichment mechanism by determining the mineralogical and geochemical properties of gabbroic formations. The meta-gabbroic rocks in the study area can be divided into three subgroups based on the size distribution (fine, medium, and coarse) of the minerals. The ore-bearing minerals observed in the meta-gabbroic rocks are construed by magnetite, ilmenite, titanomagnetite, rutile, pyrite, and hematite. The high-grade metamorphism of Menderes Massif progressively affected the gabbroic rocks resulting in the partial and complete transition of ilmenite minerals to rutile. However, the effect of metamorphism gradually decreases from outward to inward zones of the intrusion allowing an intact vanadiferous ilmenite-rich core in the entire gabbro body. The V enrichments are both hosted by oxide and sulphide-bearing phases. While the oxide phases are constituted by ilmenite and Ti-magnetite exsolutions, the sulphide minerals are pyrite and minor chalcopyrite. The V content of the studied meta-gabbro range from 281 to 628 ppm, with an average of 514 ppm. Contents of SiO2, Al2O3, Fe2O3, MgO, TiO2, and P2O5 are between 68.8-38.9%, 7.93-15.4%, 6.87-17.8%, 3.21-8.86%, 1.24-5.64%, 0.19-1.13%, respectively. V shows moderate to strong correlation with Ti, Zn, and Ga (R2= 0.51, 0.86, and 0.87, respectively) and there is a lack of correlation with Fe, Ni, and Cu indicating V3+ ion substituted Fe3+ in magnetite and Ti3+ in ilmenite. The other meta-gabbro intrusions of Menderes Massif generally lacked Ti-V enrichments, therefore Alaşehir meta-gabbro intrusion may gain economic importance in case of a tighter supply trend of these critical elements.Keywords: Vanadiferous gabbro; Magnetite; Ilmenite; Menderes Massif; Alaşehir-Manisa (Türkiye)
Monitoring global 30-m impervious surface changes from 1985 to 2020 using dense time-series Landsat imagery
Authors: Zhang Xiao
Published: March 2024

Accurately mapping impervious surface dynamics has great scientific significance and application value for urban sustainable development research, anthropogenic carbon emission assessment and global ecological environment modeling. In this study, a novel and automatic method by combining the advantages of spectral generalization and automatic sample extraction strategy was proposed and then an accurate global 30 m impervious surface dynamic dataset (GISD30) for 1985 to 2020 was produced using time-series Landsat imagery on the Google Earth Engine cloud-computing platform. Firstly, the global training samples and corresponding reflectance spectra were automatically derived from prior global 30 m land-cover products after employing the multitemporal compositing method and relative radiometric normalization. Then, spatiotemporal adaptive classification models, trained with the migrated reflectance spectra of impervious surfaces from 2020 and transferred pervious surface samples in each epoch for every 5°×5° geographical tile, were applied to map the impervious surface in each period Furthermore, a spatiotemporal consistency correction method was presented to minimize the effects of independent classification errors and improve the spatiotemporal consistency of impervious surface dynamics. Our global 30 m impervious surface dynamic model achieved an overall accuracy of 90.1% and a kappa coefficient of 0.865 using 23,322 global time-series validation samples. Cross-comparisons with five existing global 30 m impervious surface products further indicated that our GISD30 dynamic product achieved the best performance in capturing the spatial distributions and spatiotemporal dynamics of impervious surfaces in various impervious landscapes. The statistical results indicated that the global impervious surface has doubled in the past 35 years, from 5.116×105 km2 in 1985 to 10.871×105 km2 in 2020, and Asia saw the largest increase in impervious surface area compared to other continents, with a total increase of 2.946×105 km2. Therefore, it was concluded that our global 30 m impervious surface dynamic dataset is an accurate and promising product, and could provide vital support in monitoring regional or global urbanization as well as in related applications.
How lake breezes impact convection on the Tibetan Plateau: A large-eddy simulation study
Authors: Han Cunbo , Zhang Yunshuai , Ma Yaoming
Published: March 2024

Lake breezes are verified to play an important role in atmospheric boundary-layer development, convection triggering, and the transition from shallow to deep convection. The Tibetan Plateau (TP), known as the “Asian water tower”, contains more than 50% of China’s lakes in terms of area. In his study, we investigated the convection development in summer afternoons over lakeside land on the TP, the interaction between lake breezes and shallow convection triggering, the effect of lake diameter on the transition from shallow to deep convection, and the mechanism of soil moisture changes in lakeside land affecting the convection development. Using the WRF-LES model, which couples the lake model and land surface model in an idealized configuration, we performed two sets of idealized simulations with varying lake diameter and soil moisture content in the WRF-LES and found that: 1) larger lakes produce stronger lake breeze circulations and more moisture is advected from the lake to the lakeside land and lifted, creating wetter and boarder shallow convective clouds which accelerating the transition to deep convection; 2) The dryer soil induces stronger lake breeze circulations, which is beneficial for lifting the air parcels and generating moisture advection to maintain shallow convection over the lakeside land; 3) However, shallow convective clouds cannot be moistened and widened and develop into deep convection without sufficient evaporation from the ground surface in dry soil moisture conditions. Our simulation results highlight the importance of the horizontal and vertical transport of moisture by the lake breeze circulations in moistening and broadening shallow convective clouds and developing into deep convections.
The Acceleration of Uplift in the Central Taurides due to Continental Fragment Collision in the Subduction Zone of the Eastern Anatolian Region
Authors: Clark Stuart , Lou Peigen
Published: March 2024

The dynamics of subducting lithosphere with an embedded continental fragment is complex, with rapid changes in plate kinematics, mantle flow and uplift of the overriding plate as the fragment impacts the trench. However, the sequence and timing of the effects is often difficult to constrain, leading to uncertainties in the exact causes for particular subduction zones. We conducted 2D and 3D numerical modelling of subduction with Underworld2.0 to investigate the interactions between the subducting lithosphere and an embedded continental fragment, the Eratosthenes Seamount in the Cyprus subduction zone. Due to the uncertainty in the size of the continental crust around the Eratosthenes Seamount, we varied the size of the fragment from 200 km to 400 km (trench perpendicular) and compared to 3D model with a fixed seamount. The 3D model matches the regional seismic tomography models that show the absence of lithosphere on the subducting slab ahead of the continental fragment. In all the models, the subduction zone first develops as expected as the continental fragment approaches the trench. As the fragment contacts the trench at 6.5 Ma, the first uplift in Anatolia is experienced. However, the pace of uplift increases dramatically at 450 ka as the slab tear develops and the mantle flow pattern changes. The observed uplift rate before 450 ka is 0.07 mm/yr while after 450 ka, the uplift rate increases to 3.21 – 3.42 mm/yr. The model that best matches the size of the fragment is 200 km with a rate of 0.04 mm/yr before 450 ka and 1.76 mm/yr after 450 ka. The reference uplift rate from the model without the slab break-off from 450 ka is only 0.02 mm/yr.  The models demonstrate that the slab tear and break-off caused by the impact of the Eratosthenes Seamount causes the uplift observed and in particular is responsible for the more rapid uplift rates observed since 450 ka in the Central Taurides. 
The effect of surge inundation on shallow groundwater salinity in the coastal low-lying poldered area of southwest Bangladesh-a 3D model investigation
Authors: Tsai Chi San , Mo Hoque , Butler Adrian P
Published: March 2024

Pervasive salinity in soil, surface water and groundwater is a significant challenge in many coastal poldered areas of Bangladesh. These areas are characterized by their vulnerability to cyclone-induced surge inundation due to the low-lying flat topography and their concave coastal profile. The surge water leads to the areas being inundated, which may result in elevated salinity levels in surface water and groundwater. High salinity can affect the availability of potable water and have a serious impact on agriculture, ecosystems, and the health of coastal communities. To effectively address the issue of groundwater salinity in these coastal areas, a comprehensive understanding of the contributing causes is required. A 3D model, HydroGeoSphere, was developed to examine the effect of surge inundations on surface and groundwater salinities. This model coupled surface and subsurface domains, using surge levels data from Chittagong station and a digital elevation model from USGS Earth Explorer. Evaporation and monsoon data were collected at the pond of the DAB site (Dacope, Khulna, Southwest coastal Bangladesh). The results show that even one year after the storm surges, salinity levels in the surface and near-surface areas remained elevated. The high salinity levels near the surface area may be primarily due to the surge water being trapped in depressions, as well as the effects of evaporation reducing the water content of the soil, leaving concentrated salt behind. Also, low-permeable sediments in the area may contribute to the persistent high salinity levels. The modelled groundwater salinity distributions showed good agreement with the measured groundwater salinity distributions derived from electrical conductivities obtained in 14 tube wells at various depths and locations along a cross-section.
Present-day stress field in Sichuan-Yunnan region based on comprehensive updated earthquake focal mechanisms catalog
Authors: Tian JianHui , Gao Yuan , Li Ying
Published: March 2024

The Sichuan-Yunnan region of the SE and E margin of the Tibetan Plateau, situated at the transitional nexus between the seismically-active intensely-deformed Tibetan Plateau and the tectonically stable Yangzi block with comparatively low seismicity, has experienced substantial geological transformations during the Quaternary. Given the pronounced seismicity, there is an escalating imperative for an accurate and refined distribution of the stress field in the region. To unravel the contemporary stress state within major active blocks and along active faults in the study area, an elaborate computation of their tectonic stress field is undertaken by comprehensive updated earthquake focal mechanisms catalog. The tectonic stress field in Sichuan-Yunnan region exhibits obvious lateral variations, with the principal compressive stress direction demonstrating a notable correlation with the azimuth of the P axis. The directions of the stress field show a variation from north to south at ~ 28°N. The directions of the maximum and minimum principal compressive stress in the north show nearly E-W compression and N-S tension, respectively. Conversely, in the south, there is a discernible clockwise rotation trend from east to west. Localized normal faulting stress regimes are observed in the middle section of Xianshuihe fault and southwest side of Litang fault. The extensional environment of the former may be attributed to the tectonic activities such as block translation, clockwise rotation and vertical uplift, as well as the clockwise rotation of the Xianshuihe fault from NW-SW to NNW-SSE. The latter may be related to the extensional structures, rift basins and the normal fault movements in the crust formed by the detachment of the plates and delamination of the mountain roots at the end of Triassic. We also found that the tectonic stress field under the large faults, such as Longmenshan fault, Red River fault, Xiaojiang fault and Lijiang-Xiaojinhe fault, show segmented variation. The findings yield invaluable insights into the intricate dynamics of tectonic deformation along the SE margin of the Tibetan Plateau [supported by NSFC Projects 42330311, 42074065 & 41730212].
Changes in Photospheric Lorentz Force in Eruptive and Confined Solar Flares
Authors: Maity Samriddhi Sankar , Sarkar Ranadeep , Chatterjee Piyali , Srivastava Nandita
Published: March 2024

Solar flares are known to leave imprints on the magnetic field at the photosphere, often manifested as an abrupt and permanent change in the downward-directed Lorentz force in localized areas inside the active region. Our study aims to differentiate eruptive and confined solar flares based on the vertical Lorentz force variations. We select 26 eruptive and 11 confined major solar flares (stronger than the GOES M5 class) observed during 2011-2017. We analyze these flaring regions using SHARP vector-magnetograms obtained from the NASA's Helioseismic and Magnetic Imager (HMI). We also compare data corresponding to 2 synthetic flares from a delta sunspot simulation reported in Chatterjee et al. We estimate the change in the horizontal magnetic field and the total Lorentz force integrated over an area around the polarity inversion line (PIL) that encompasses the location of the flare. Our results indicate a rapid increase of the horizontal magnetic field along the flaring PIL, accompanied by a significant change in the downward-directed Lorentz force in the same vicinity. Notably, we find that all the confined events under study exhibit a total change in Lorentz force of < 1.8 x 10^22 dyne. This threshold plays an important factor in effectively distinguishing eruptive and confined flares. Further, our analysis suggests that the change in total Lorentz force also depends on the reconnection height in the solar corona during the associated flare onset. The results provide significant implications for understanding the flare-related upward impulse transmission for the associated coronal mass ejection.
Characterising transport and emplacement mechanisms of volcanic debris avalanches through 3D Micro Tomography. 
Authors: Procter Jonathan , Mills Shannen , Zernack Anke , Mead Stuart , Stevenson Andrew , Arhatari Benedicta
Published: March 2024

Volcanic communities near long-lived stratovolcanoes are susceptible to the significant threat associated with edifice collapse events which produce volcanic debris avalanches. These events can have runout distances > 100 km and are the largest mass flows on Earth with volumes ranging from 0.1 to 100 km3 which have the potential to bury large sectors of the landscape posing a severe risk to people and infrastructure. However, the emplacement mechanisms of these large destructive phenomena are still poorly understood with the inability to accurately quantify the physical parameters such as frictional regimes, velocity, and temperature which contribute to the extreme runout. The internal structure and minerology of the avalanche deposits hold the key to understanding the transportation mechanisms. During transportation inter-particle collision and shearing occurs reducing grainsize and generating new minerals such as Pseudotachylytes, Frictionites and Silica polymorphs along shear zones between larger clasts and along the base of the flow. Twenty-five volcanic debris avalanches and rock avalanches of varying sizes were sampled from New Zealand and the USA to provide a representative variety of flow types to better understand transportation mechanisms. Using 3D Micro-Computed Tomography at the Australian Synchrotron the internal structure of the avalanche deposits were analysed to identify different minerals and structures present. Analysis of the microstructures of the samples show a variety of different fracture patterns that can be categorized based on the different source lithologies sampled as well as the different rheological emplacement conditions from the collapse and flow.  Features seen at the micro-scale mimic larger centimeter to meter scale features traditionally observed in the flow.  Investigating the formation of new minerals along collision and shear zones can provide insights on the physical constraints of the flow e.g., velocity and temperature. Data from this study will provide quantitative input parameters forming the foundation for developing a model for transportation and emplacement of long-runout volcanic debris avalanches. Data from these models can be used to assess the volcanic debris avalanche hazards from volcanoes globally, better informing risk assessments.
Drought risks based on changes in atmospheric evaporative demand due to plant response to CO2 levels
Authors: Ha Kyung-Ja , Yeo Ji-Hye , Kim Daeha , Lee Hyeonho
Published: March 2024

The temperature and CO2 increase due to global warming are expected to exacerbate atmospheric water demand, worsening future drought conditions. Recent studies have revealed that evapotranspiration is regulated by stomatal response in response to CO2 increase. However, understanding droughts defined based on evapotranspiration remains incomplete as it does not adequately integrate plant responses to anticipated drought conditions. In this study, we aimed to evaluate the frequency and extent of future drought events by comparing the Evaporative Stress Index (ESI) using two potential evapotranspiration (Ep) values capturing atmospheric evaporative demand. The first Ep utilized past data and predictions from the Coupled Model Intercomparison Project Phase 6, assuming a constant surface resistance (rs) without considering plant responses. The second Ep accounted for the sensitivity of rs to increased CO2. Our findings indicate a significant increase in rs due to elevated CO2, leading to substantial changes in drought frequency and extent. While both non-vegetative response and plant response are expected to increase in future scenarios, an ESI that ignores plant responses tends to overestimate drought risk. Therefore, our study emphasizes the importance of integrating the sensitivity of rs to evaporative demand and CO2 level increases when assessing drought risk.
Abrupt increase in Arctic-Subarctic wildfires following permafrost thawing in a warmer climate
Authors: Kim In-Won , Timmermann Axel , Kim Ji-Eun , Rodgers Keith , Lee Sun-Seon , Lee Hanna , Wieder William
Published: March 2024

Greenhouse warming is accelerating permafrost thaw and the risk of wildfires in the northern high latitudes. However, the impact of permafrost thaw on Arctic-Subarctic wildfires and the associated release of greenhouse gases and aerosols is less well understood. Here we investigate the effect of future permafrost thaw on Arctic-Subarctic wildfires using the CESM2 large ensemble simulations forced by the SSP3-7.0 greenhouse gas emission scenario. We find that an increase in soil permeability induced by rapid permafrost thawing leads to an abrupt increase in sub-surface runoff and a decrease in soil moisture over the Arctic-Subarctic region. This sudden soil drying causes a significant increase in surface air temperature and a decrease in relative humidity during summer. The resulting soil drying and atmospheric dryness lead to a rapid intensification of wildfires in western Siberia and Canada in the mid-to-late 21st century.
Distribution and valuation of the biological carbon pump and its carbon sequestration:  Implications for international area-based management and climate finance
Authors: Berzaghi Fabio , Pinti Jerome , Aumont Olivier , Maury Olivier , Wisz Mary
Published: March 2024

Marine organisms, from plankton to fish, provide a wealth of ecosystem services, including carbon sequestration in a process known as the ocean’s biological carbon pump (BCP). The BCP brings carbon from the atmosphere to the ocean depths where it is stored for decades to centuries. Although parts of the ocean’s BCP are under threat from human activities,  BCP carbon sequestration rarely features as an objective in efforts to protect ocean spaces. Moreover, although BCP carbon sequestration services could support discussions of conservation and climate finance,  its economic value has yet to be estimated in space and time.Biogeochemical modeling and mapping efforts have grown in recent years, and emerging results could potentially help to fill in important spatially explicit and economic knowledge gaps that could inform the protection of the BCP. We developed a new metric to map and quantify the global ocean’s BCP long-term carbon sequestration and computed its value on a potential carbon market. We show the  global spatial patterns and valuation in relation to geopolitical and management boundaries, and highlight options for governance and management. Our results highlight potential opportunities for preserving the climate services of the BCP both nationally and in areas beyond national jurisdiction , and can be used to inform discussions about marine protected areas, environmental impact assessment, and conservation finance.
The structure of Jupiter and Saturn's winds below the cloud level - insights from high harmonics gravity measurements
Authors: Galanti Eli , Kaspi Yohai , Durante Daniele , Iess Luciano
Published: March 2024

Strong and persistent zonal winds at the cloud level characterize both Jupiter and Saturn. Based on  Juno and Cassini's measurements of the low-order gravity harmonics up to J10,  it was shown that the observed cloud-level winds penetrate inward parallel to the planet's spin axis and decay at a depth of around 3,000 km and 9,000 km, respectively. However, because of the limited number of measured gravity harmonics, the latitudinal structure of the flows could not be uniquely determined, so only an overall estimate of their depth was obtained. Here, we present new gravity analyses for both gas giants, based on the original Juno and Cassini measurements,  but in which the magnitude of harmonics higher than J10 is constrained at the less observable high latitudes. This enables resolving the gravity field up to J40 for Jupiter and J20 for Saturn, while being consistent with the previous gravity measurements.  We then use the high harmonics to better constrain the structure of the zonal flows below the observed cloud level, revealing the latitudinal variations in the depth of the flows. We show that for Saturn, the mid-to-high latitude jets must be shallower than the low-latitude winds, while in Jupiter, the low-latitude winds dominate the gravity signal. In the talk, we will review the similarities and differences between the two gas giants arising from our results and discuss their implications for our understanding of gas giant dynamics.
Insights into the September 8, 2023, MW 6.8 earthquake in Morocco: a deep transpressive fault along the High Atlas Mountain belt
Authors: Cheloni Daniele , Famiglietti Nicola Angelo , Tolomei Cristiano , Caputo Riccardo , Vicari Annamaria
Published: March 2024

On September 8, 2023, a magnitude 6.8 earthquake impacted the High Atlas Mountains in western Morocco, approximately 70 km southwest of Marrakesh, resulting in significant devastation and casualties. This study delves into a comprehensive geodetic dataset, utilizing interferometric synthetic aperture radar (InSAR) measurements to analyze the fault segment accountable for the seismic occurrence. Our findings propose two potential fault scenarios: a transpressive NNW-dipping high-angle fault (70°), associated with the Tizi n’Test alignment, or a transpressive SSW-dipping low-angle fault (22°) linked to the North Atlas Fault, where slip (up to 2.2 m) is observed predominantly in deeper sections of the fault. Although seismic catalogs were inconclusive regarding the dip direction of the fault, evidence from mainshock locations, gravity and heat-flow data, along with modeling, and the active shortening direction, collectively indicate the activation of a low-angle, southwesterly dipping oblique thrust of the North Atlas fault during the 2023 Moroccan earthquake. Integrating interferometric analyses with geological, tectonic, and seismological data could be crucial for resolving ambiguities in satellite-based models. This study therefore underscores the complexity of fault identification and the need for a multidisciplinary approach in understanding seismic events.
Microseismic Characteristics: Seasonal Variations, Periodic Changes, and Oceanic Influences in the Korean Peninsula
Authors: Jang Yong-seok , Lee Woo-dong
Published: March 2024

The understanding of microseism-source characteristics has become increasingly important, particularly in the context of retrieving Green's functions, which play a crucial role in various fields of seismology. This study aims to elucidate the characteristics of microseismic sources, encompassing seasonal variations in the activity of primary and secondary microseisms, along with periodic changes observed in microseismic peaks. The analysis involved data from seven stations carefully selected from the Korean Meteorological Administration seismic network, each with over 10 years of continuous data. Employing cross-correlation techniques, we calculated Empirical Green's Functions (EGFs) between 17 station pairs. The averaged spectra of the calculated EGFs revealed two primary peaks, concentrating energy distribution around 18 seconds and in the period range of 2-5 seconds, aligning with the peaks associated with Primary and Secondary microseism. We then categorized spectral energy distribution data into less than and more than 10 seconds, aiming to discern distinct characteristics associated with the two microseismic peaks. Subsequently, we examined average temporal energy variations for each microseism, generating, we say, spectral-time series data by summing and averaging separated energy in the period direction, and calculating energy variations for each period using a multi-filtering technique (MFT). Observing prominent dominant changes with a 1-year period in both Primary and Secondary microseisms, we noted additional periodic variations with 6 months, 3 months, and 2 months in Secondary microseism. Specifically focusing on 1-year period changes, Primary microseism displayed dominance during the summer, with lower energy levels in the winter across the entire area. For Secondary microseism, 1-year period changes often showed the lowest values in the summer and the highest values in the winter. Additionally, in Secondary microseism, maximum or minimum values were observed in the spring and autumn, resembling patterns observed in Primary microseism. Simultaneously, we reconstructed the dominant period of ocean gravity waves from Wave Watch III to explore the effect on microseisms around the stations used in this study. Comparing this data with calculated the spectral time series data of Primary and Secondary microseisms revealed not only a match in the 1-year period but also in detailed phases below 1 year. This implies a close relationship between microseisms around the Korean Peninsula and ocean activities, prompting future research to delve into detailed periodic changes, correlate them with ocean activities, and identify their underlying causes.