bluuebunny/crossref_metadata_2025 huggingface dataset:
Applications of geophysical techniques for the analysis of the internal structure and understanding of the hydrological system of the Kinzl Covered Glacier, Cordillera Blanca, Peru 
Authors: Chacca Luna Velnia , Jara Infantes Widmark Harrinson , Cosi Fajardo Manuel Antonio , Aquino Morales Milagros Lizbeth , Mamani Yampi Leila , Cachay Sara , Torres Lázaro Juan Carlos
Published: March 2024

The Cordillera Blanca is currently home to 384 covered glaciers, which constitutes 46.5 % of the total of 825 covered glaciers registered in the 20 glacier ranges of Peru, according to data provided by the Glacier Inventory 2023 (INAIGEM, 2023). Therefore, in the framework of climate fluctuations driven by global warming, covered glaciers stand out as crucial elements, as their level of thawing is much slower in response to climate variability and in contrast to their debris- free glacier counterparts. This characteristic consolidates them as increasingly essential and valuable water resources.The objective of the study is to determine the physical characteristics of the Kinzl Covered Glacier, located in the Cordillera Blanca, by applying the geophysical methods of ground penetrating radar (GPR) and vertical electrical sounding (VES). The methodology employed includes georadar profiling and point soundings to understand the composition and distribution of materials and the physical properties of the glacier. From the detailed analysis of electrical soundings and georadar profiles, a correlation of both methods has been achieved through the resistivities obtained and established for similar environments, with phases of reflected signals coming from the contours of the interfaces identified in the radargrams analysed and interpreted. This correlation has provided us with a comprehensive understanding of the internal characteristics of the Kinzl Covered Glacier, where three horizons have been identified: The first horizon composed of variable surface debris, ranging from 2 to 9 metres thick, with resistivities that remain above 16k Ohm.m; the second horizon composed of massive ice with debris, fluctuating between 40k and 300k Ohm.m and with thicknesses ranging from 40-60 metres, parallel to this horizon we also have massive ice corroborated by values of 400k and 6000k Ohm.m with thicknesses exceeding 60 metres and below this we have a third horizon composed of bedrock with average resistivity between 1.2k and 9k Ohm.m. These data found in the Kinzl Covered Glacier fit with those frequently found in glacial-periglacial deposits in the Andes.The results provide a comprehensive understanding of the internal characteristics of the Kinzl Covered Glacier, highlighting its relevance for understanding the complexity and implications for glacial dynamics. These findings are valuable for numerical modelling, glacier risk management and water resource management.
Evolution trend of snow cover and simulation of snowmelt runoff in upper reaches of Lancang River
Authors: Zhang jujia
Published: March 2024

Affected by global climate change, the variations of snow cover and snowmelt runoff in the high cold region has raised an increasing concern. Snowmelt water is an important component of spring runoff in the Lancang River basin, and it is of great significance for the scientific operation of cascade hydropower stations in the Lancang River basin to master the variation law of snow cover in the upper reaches of the Lancang River and accurately simulate the snowmelt runoff process. Based on the remotely sensed snow cover data from 2000 to 2019, the Mann-Kendall trend test method was used to analyze the spatio-temporal variation of snow cover in the upper reaches of Lancang River. An snowmelt runoff model was established, and the PSO algorithm was introduced to determine the model parameters to simulate the snowmelt runoff process. The results show that the snow cover in the upper reaches of Lancang River showed no significant increase in spring, autumn and winter, and no significant decrease in summer. The average annual snow cover in spring, summer, autumn and winter was 0.16, 0.06, 0.13 and 0.17, respectively. The snow cover in the southwest and north of the Lancang River source area increased in all seasons, while the snow cover in the southeast area decreased. Among them, the increase of snow cover in the northwest reaches the largest in winter, up to 3%/a. The SRM model has good applicability in the upper reaches of the Lancang River, and the certainty coefficients of calibration period and verification period are 0.87 and 0.78, respectively, and the results have a certain implication for the simulation of snowmelt runoff in the alpine region.
Assessing the Evolution of Intensity – Duration – Frequency Curves over Greece: A Comparative Study between 2016 and 2023
Authors: Serafeim Athanasios V. , Emmanouil Stergios , Perdios Anastasios , Langousis Andreas
Published: March 2024

The development and regular revision of the Greek National Flood Risk Management Plans (FRMPs) serve as direct response to the guidelines introduced by the Floods Directive (Directive 2007/60/EC) of the European Parliament and of the Council, in order to effectively mitigate and manage potential risks related to extreme precipitation events. The current study presents a comparison between: a) the Intensity-Duration-Frequency (IDF) curves obtained in 2016 over Greece using the Koutsoyiannis et. al (1998) methodology, and b) their 2023 revised version using a more recent approach (Koutsoyiannis, 2022; Iliopoulou et al., 2022).Through a comparative analysis of the two distinct IDF sets, we assess the inherent statistical variability of rainfall fields and its probable influence on extreme rainfall estimation. Focus is on determining both the nature and extent of potential spatiotemporal alternations, while identifying emerging trends and possible abnormalities that indicate substantial shifts in precipitation patterns, thus enhancing understanding of the evolution of flood risk over Greece.As the IDF curves form the cornerstone of Flood Risk Management Plans, it is crucial to identify significant variations in their profiles over short periods of time. Consequently, the current work highlights the necessity for regular updates of the national Flood Risk Management Plans, in accordance with the Floods Directive guidelines, while identifying areas that exhibit substantial statistical variability. Ultimately, the obtained results will allow for the development of robust decision-making frameworks, enabling stakeholders and policymakers to develop flexible and compliant mitigation strategies against potential hydrological hazards to protect the community and infrastructural assets. ReferencesIliopoulou, T., Malamos, N. and Koutsoyiannis, D. (2022) Regional ombrian curves: design rainfall estimation for a spatially diverse rainfall regime, Hydrology, 9(5), 67, https://doi.org/10.3390/hydrology9050067.Koutsoyiannis, D., Kozonis, D. and Manetas, A. (1998) A mathematical framework for studying rainfall intensity-duration-frequency relationships, Journal of Hydrology, 206 (1-2), pp 118-135, https://doi.org/10.1016/S0022-1694(98)00097-3.Koutsoyiannis, D. (2022) Stochastics of Hydroclimatic Extremes - A Cool Look at Risk, 2nd Edition, ISBN: 978-618-85370-0-2, 346 pages, Kallipos Open Academic Editions, Athens, 2022, https://doi.org/10.57713/kallipos-1.
Frictional behavior of chlorite in large-displacement experiments under hydrothermal conditions
Authors: Qin Weifeng , Yao Lu , Shao Tongbin , Feng Wei , Chen Jianye , Ma Shengli
Published: March 2024

The frictional properties of faults are primarily controlled by their mineral composition, as well as ambient and deformation conditions, such as temperature, pore fluid, normal stress, and slip displacement. While many studies have been conducted to decipher how temperature and pore fluid may affect the frictional behavior of faults, less attention has been paid to the slip displacement effects, especially under hydrothermal conditions. By employing a rotary shear apparatus equipped with an externally-heated hydrothermal pressure vessel, we conducted large-displacement (up to 521 mm) friction experiments on chlorite under temperature (T) of 25 to 400℃ and pore water pressure (Pp) of 30MPa. The imposed effective normal stresses were 200 MPa and the slip rates ranged from 0.4 to 10 μm/s. The experiments unveiled significant slip strengthening in chlorite within the temperature range of 25 to 400 °C. Moreover, with increasing temperatures, there was an overall increasing trend in both the rate of slip strengthening and the ultimate frictional strength. For example, under T = 25 °C, the friction coefficients at displacements of 5, 90, and 521 mm were 0.33, 0.49, and 0.59, respectively, in contrast to 0.46, 0.79, and 0.88, respectively, at the same three displacements under T =400 °C. Under all the temperature and displacement conditions, chlorite exhibited velocity strengthening behavior without discernible temperature dependence, although the velocity-dependence parameter (a-b) increased with slip displacement. Microstructural analysis revealed that, the entire layer of the chlorite gouge experienced pervasive and intense shear deformation after slip of 521 mm, with extremely remarkable grain-size reduction. The thermogravimetrical and FTIR data of the deformed chlorite samples, together with the microstructural data, suggest that the dehydroxylation and the distortion of crystal structure of chlorite might occur during the friction experiments conducted at T ≥ 200 °C. Such changes may explain the more pronounced slip strengthening of chlorite with increasing temperatures towards 400 °C. This explanation can be further demonstrated by a comparative experiment conducted under varying temperatures (400°C for the first 100 mm of slip, followed by 25°C for the rest of 100 mm slip), wherein the friction coefficient at T = 25°C during the latter stage of slip remains as high as that at T = 400°C. These findings highlight the importance of slip displacement in controlling the frictional strength and its variations of chlorite-bearing faults at depths, and have profound implications for understanding the fault slip behaviors and earthquake mechanisms in subduction zones.
Hotter Mantle Precludes Supercontinent Assembly in Pacific Hemisphere
Authors: Mitchell Ross , Doucet Luc
Published: March 2024

There are strikingly contrasting predictions about which oceans will close to create Earth’s next supercontinent, namely the introversion (close the Atlantic), extroversion (close the Pacific), and orthoversion (close other orthogonal oceans) models. We demonstrate that recently obtained seismically inferred hotspot temperatures exhibit a deep mantle hemispheric dichotomy, with hotspots in the Pacific hemisphere being statistically hotter than those in the African hemisphere. This stronger thermal upwelling in the Pacific rules out that the Pacific Ocean may be closing as continents tend to drift down, not up, long-wavelength topography. Extroversion is therefore not viable for the formation of the next supercontinent.
The origin of water in the large igneous provinces: constraints from hydrogen isotope
Authors: Liu Jia , Xia Qunke , Zhou Jingjun
Published: March 2024

Large igneous provinces (LIPs), characterized by massive basaltic lava flows and rapid formation over short time frames, exert profound effects on Earth's environment, climate, and mineral resources. Although prior studies have revealed that high water content in the mantle sources would be a critical factor for the genesis of LIPs, the origin of water in their mantle sources remains debated, posing a critical challenge for understanding the geodynamic context of LIP formation and associated deep mantle processes. The water can derive from the primordial components that build the earth, or from the earth surface carried by the subducted oceanic slabs. Here, we conducted coupling analysis of water contents and hydrogen isotopes of the melt inclusions and quenched glasses from the high 3He/4He picrites in Western Greenland and low-Ti type picrites from Emeishan large igneous province. The results show that the high H2O/Ce (>1300) and normal mantle like D/H ratio of the primary magma are distinct to that of the oceanic island basalts and Archean komatiites. Combining the high mantle potential temperature and non-arc like trace elemental patterns, we suggest that the ELIP taps highly hydrous reservoirs in the deep mantle, potentially with water inherited from earth-building materials or the less dehydrated subducted oceanic lithosphere. Our work also raises the caution that the traditionally combined water content and δD analysis for OHMs does not necessarily allow the accurate determination of water concentration of the primary magma. For Western Greenland picrites, the results show water contents from 850 to 1050 ppm by weight, but large variable δD from -75± to -140±8 ‰, which forms the trends well modeled by the kinetic fractionation driven by inward water diffusion into the melt inclusions. The primary δD of the these picrites were inferred to be around -80 ‰, consistent with the recent results for the high 3He/4He submarine basaltic glasses from Loihi, Hawaii. Thus, our work may support a globally consistent primordial water in the origin of chondritic material.
Improved long-range forecasts in South Korea through integrated forecast information
Authors: Kim OKYeon , Im Seul-Hee , Kim Gaeun
Published: March 2024

We explored the objective methods to improve long-range forecasting through enhanced forecast skills and integrated forecast information. The objective process we used in this study includes the selection of monitoring factors for more reliable monthly seasonal forecasts. Therefore, we chose the three most significant monitoring factors, i.e., ENSO, snow cover over Eurasia Continent and Arctic sea ice. We first examined the effect and response of the monitoring factors on the boreal winter temperature in South Korea. To improve the information related to the ENSO in seasonal forecasting, the impact of the tropical precipitation which act as an oceanic ENSO forcing was investigated. As one of the important monitoring factors for boreal winter temperature prediction, we analyzed the availability of the index describing austral Eurasian snow cover. We also analyzed the usage of Arctic conditions for predicting monthly temperature for boreal winter. We then investigated how well the effect and response of the factors are simulated in the operational seasonal models. Finally, the link between observation-based monitoring factors and model-based prediction is proposed for objective forecasting.
Vulnerability assessment of groundwater recharge under extreme climate change in coastal area watershed of South Korea
Authors: Woo So Young , Chang Sun Woo , Kim Mingyu
Published: March 2024

In recent times, climate change leads to the occurrence of extreme weather phenomena such as heavy rainfall, severe drought, heatwaves, and cold spells. From the perspective of the watershed hydrologic cycle, these changes have resulted in adverse effects, including an increase in surface runoff, evapotranspiration, and a decrease in groundwater recharge. Coastal areas, in particular, have a greater reliance on groundwater compared to inland watershed, making water resources vulnerable to climate change. Therefore, in this study, the Soil and Water Assessment Tool (SWAT) was implemented for the An-Seong-cheon watershed (1,627 km2), which is adjacent to the coastal region in South Korea. The SWAT was calibrated and validated for runoff and evapotranspiration. The estimation of groundwater recharge was conducted based on the calibrated water balance components, the average recharge was calculated to be 21.2% for the study area. Subsequently, extreme climate change scenarios were selected, by examining the Shared Socioeconomic Pathway (SSP) scenarios derived from the Intergovernmental Panel on Climate Change's Assessment Report 6 (AR6). The extreme climate change scenarios will be applied to the SWAT model to project future changes in groundwater recharge. Ultimately, the purpose of study is to evaluate the climate change vulnerability of groundwater recharge based on land cover characteristics within the coastal watershed.Key words: Coastal area, Climate Change, Groundwater recharge, Vulnerability Assessment, SWATAcknowledgeResearch for this paper was carried out under the KICT Research Program (project no.20230166-001, Development of coastal groundwater management solution) funded by the Ministry of Science and ICT.
Improving Biochar Suitability for Arid-Land Use: Impact of Elemental Sulfur and Compost on Acidification and Biological Activation
Authors: Al Rabaiai Ahmed , Menezes-Blackburna Daniel , Al-Ismailya Said , Janke Rhonda , Al-Alawi Ahmed , Al-Kindi Mohamed , Bol Roland
Published: March 2024

This study aimed to enhance the quality of biochar for applications in arid lands by employing elemental sulfur (S, 0.013%) as an acidifying agent and compost (10%) as a biological activator. The addition of elemental sulfur significantly reduced the biochar pH, with the most substantial decrease from 8.1 to 7.2 observed when co-amended with vermicompost was used. Elemental sulfur markedly increased the water-soluble concentrations of calcium (Ca) by 147% and 105%, as well as magnesium (Mg) by 929% and 447% in compost and vermicompost, respectively. This suggests a decline in biochar basicity due to acid mineral dissolution and desorption. Sulfate (SO42-) levels showed the greatest increase when compost was co-applied with sulfur, indicating more efficient oxidation in this treatment. FT-IR analysis revealed increased carbonyl groups (C=O) and decreased alkyne (C≡C) groups in compost and vermicompost-treated samples, while sulfur treatment resulted in the decrease of hydroxyl groups, but only in the presence of vermicompost. SEM-EDX analysis demonstrated changes in the elemental composition and microscale pore structure of biochar samples after incubation with sulfur. Sulfur amendments stimulated substrate-induced respiration, particularly in biochar amended with sulfur (BS, 0.011 ug CO2- C/g/h) and biochar with vermicompost (BV, 0.18 ug CO2- C/g/h) treatments. Microbial diversity (Shannon H) significantly increased in compost treatments with sulfur amendment from 3.08 to 4.52, while it decreased in vermicompost from 4.25 to 4.02. Vermicompost treatments (BV, BVS) exhibited higher microbial evenness (0.27 and 0.28) and equitability (0.67) diversity indices. The bacterial community structure was significantly influenced by all treatments, with sulfur reducing the abundance of Proteobacteria by 30% in the presence of compost and 8% with vermicompost, while increasing the abundance of Actinobacteria by 18% and 4% for compost and vermicompost treatments, respectively.Multivariate principal component analysis (PCA) indicated that soluble sulfate was associated with specific sulfur-oxidizing bacterial clusters, which were differentially expressed under different compost treatments. Integrating biochar with sulfur and compost emerges as a promising sustainable technology for managing alkalinity, enhancing soil fertility, and improving agricultural productivity in arid regions. 
IDS contribution to the first update of the ITRF202
Authors: Moreaux Guilhem , Lemoine Frank , Capdeville Hugues , Štěpánek Petr , Otten Michiel , Nahmani Samuel , Pollet Arnaud , Schreiner Patrick
Published: March 2024

In anticipation of the first update of the 2020 realization of the International Terrestrial Reference Frame (ITRF2020), the International DORIS Service (IDS) Combination Center is participating in the estimation of DORIS stations positions/velocities as well as Earth Orientation Parameters (EOPs), using DORIS data. These computations are based on the latest weekly multi-satellite series from all four IDS Analysis Centers and two IDS Associated Analysis Centers, from January 2021 to December 2023.The primary objectives of this study are to analyze the DORIS contribution to this first update of the ITRF2020 in terms of: (1) geocenter and scale solutions, (2) station positions and week-to-week repeatability, and (3) Earth Orientation Parameters (EOPs).Comparisons with the IDS 19 series time extension (contributing to ITRF2020) will highlight the benefits of the new models, including the latest DORIS missions (e.g. HY-2C, HY-2D, Sentinel-6A MF), and the addition of two new IDS contributors. Additionally, this study will assess the impact of new strategies designed to mitigate perturbations caused by the South Atlantic Anomaly (SAA) on certain DORIS missions.
Crystallisation history of magmatic sulphide droplets in intra-oceanic arcs
Authors: Schäfer Wiebke , Keith Manuel , Regelous Marcel , Klemd Reiner , Kutzschbach Martin
Published: March 2024

Valuable understanding regarding the behaviour of chalcophile elements in magmatic systems can be gained by examining magmatic sulphide droplets, which are the solidified remnants of previously immiscible sulphide liquids [1-2]. We analysed the trace element composition of sulphide droplets by LA-ICP-MS, creating a comprehensive data set for volcanic and plutonic rocks from intra-oceanic arcs.We observed a significant enrichment of elements like Zn, Cd, Sn, Te, and Bi in sulphide droplets from lava samples compared to those hosted by gabbro xenoliths, which cannot be attributed to the fractionation of olivine, spinel, or magnetite [3-5]. These compositional differences are likely the result of changing sulphide droplet composition during cooling and solidification of the silicate melt. This process involves continuous sulphide segregation or re-equilibration with the silicate melt. A key aspect of our suggested model is sulphide droplets' resorption or partial remelting, particularly of the Cu-Fe-rich intermediate solid solution proportion. This process is driven by pressure decrease during magma ascent, leading to an increase in sulphur solubility in the silicate melt [6], which potentially liberates elements like Cu, Au, Zn, Bi, Te, and Ag from the sulphide droplet to the silicate melt. Our findings further suggest that subsequent magma stagnation and fractional crystallisation lead to a second stage of sulphide saturation, likely dominated by the elements previously liberated from the intermediate solid solution.The complex crystallisation history indicates that sulphide droplet formation during silicate melt evolution in subduction-related settings is a non-equilibrium process. We further propose that volatile saturation preceding the second stage of sulphide segregation from a silicate melt enriched in chalcophile elements liberated from intermediate solid solution could result in particularly metal-rich fluids (e.g., Cu, Au, Bi, Te) with a high ore-forming potential in magmatic-hydrothermal environments. [1] Wood, B. J. and Kiseeva, E. S. (2015), Earth and Planetary Science Letters, 424, 280-294. [2] Patten, C. et al. (2013), Chemical Geology, 358, 170–188. [3] Distler, V. V. et al., (1983), Initial Reports of the Deep Sea Drilling Project, 69, 607-617. [4] Keith, M. et al. (2017), Chemical Geology, 451, 67–77. [5] Schäfer, W. et al., in prep. [6] Peach et al. (1990), Geochimica et Cosmochimica Acta, 12, 3379-3389.
Investigating the Heat Source of Yangbajing Geothermal Field, South Tibet, with Magnetotelluric Data
Authors: Lei Lulu , Jin Sheng , Dong Hao , Wei Wenbo , Ye Gaofeng , Zhang Letian
Published: March 2024

The Yangbajing geothermal field, located in the south part of the Tibetan plateau is the largest high-temperature geothermal system of the whole plateau. Numerous hydrological, geological, and geothermal studies have been conducted to gain insights into the heat source of the geothermal system. Geothermal studies show that heat flow in this area is extremely high. However, heat flow contributed by the crustal radiogenic heating together with mantle heating still can not explain the anomalously high heat flow (~116 mW/m2) here. In this study, we use the high-resolution 3D electrical resistivity models, generated from magnetotelluric data in the Yangbajing region of southern Tibet, that image zones of enhanced conductivity in the middle crust. Such features may relate to partial melts (or magma chambers) with a melt fraction of more than 19%. Here, with the help of other available data, primarily hydrothermal and geochemical data, we estimated the heat flow generated by the partial melts in this area. Furthermore, we performed a set of simulations to reproduce the thermal evolution of the magma chambers in this region. our results indicate that the magma chambers below the study region may provide sufficient heat flow to fill the relatively large heat flow gap (~20.25 mW/m2 ), apart from the mantle heat conduction and radiogenic heating for the geothermal system. In addition, the thermal evolution simulations show that the magma chambers beneath the Yangbajing geothermal system may remain relatively warm, after the long cooling procedure. Our results highlight the possible contribution of the magmatic heat generation to the Yangbajing geothermal system, and reveal that crust contributes a significant proportion of the total surface heat flow (~70.75 mW/m2) in the Yangbajing geothermal field, which is much higher when compared with the typical rift basins in China.
The Green Curriculum To Fight Against Climate Change
Authors: Olğun Hayriye
Published: March 2024

In the socioeconomically challenged Narlıdere Boarding Middle School, a project addressing environmental challenges was implemented. This self-sufficient model engaged students and parents in decision-making, focusing on UN Sustainable Development Goals. In this case, I improved a Green curriculum, including some implementations towards school and science lessons. These activities were implemented during one school year for 6th, 7th, and 8th-grade students. Here are the key concepts and applications of these implementations:Waste management at school was the main goal. Within this scope, recycling bins were placed in the school based on the idea that not all waste is garbage. The recyclable waste was sent to the nearby Bitlis Solid Waste Management Facility (BIKA).Domestic waste generated in the school canteen was evaluated as compost, and greenery was grown with the produced compost.Soap was made from the accumulated waste oil in the school canteen, and the soaps produced were used in the school. In this context, students brought the waste oil accumulated in their homes to the waste oil collection point at the school to be evaluated in the same context.An educational trip to BIKA for waste management and recycling was organized. Scientific knowledge was provided to the students in this field.We conducted an analysis of local water sources and mapped them with students.To be aware of our environment, we created a plant map of our local area using mobile applications. We collected rocks, classified them, and made an exhibition from them.We also built an insect hotel to raise awareness of the little animals that we share our lives with. I aimed to make my students aware of nature.The project notably increased environmental initiatives, aided national exhibition participation, and improved students' expressive abilities. Positive feedback and student engagement laid the foundation for broader project dissemination. This study highlights the significance of green skills in combating climate change for a sustainable future.Steps aligned with the Sustainable Development Goals enhanced students' environmental awareness and waste perception. Soap production from waste oil contributed to the economy and improved students' skills. There was a noticeable increase in environmental projects at school. Educational activities facilitated students' participation in national exhibitions. The science fair strengthened students' expression skills. Positive feedback throughout the process laid the groundwork for wider project dissemination. Embracing sustainable steps became the primary motivation for students. This study can be seen as a valuable step towards a sustainable future, emphasizing the importance of green skills in fostering awareness regarding climate change.
IHRF Coordination Center, a newly established IAG/IGFS component to ensure the sustainability of the IHRS/IHRF
Authors: Vergos Georgios S. , Sánchez Laura , Barzaghi Riccardo
Published: March 2024

The International Association of Geodesy (IAG) introduced the International Height Reference System (IHRS) in 2015 as the international standard for the accurate determination of physical heights worldwide. The primary vertical coordinates are geopotential numbers referenced to a conventional Wo value. The realization of the IHRS is the International Height Reference Frame (IHRF), which corresponds to a global network of reference stations with precise reference coordinates, geopotential numbers specified in the IHRS and (X, Y, Z) coordinates in the International Terrestrial Reference Frame (ITRF). In the framework of the IAG and after a strong international collaboration the scientific foundations of the IHRS have been outlined and a first realization of the IHRF has been computed. In that frame, it has been deemed necessary to ensure the long-term sustainability of the IHRF by establishing a new dedicated component within the IAG gravity field related services. Recently (December 2023), the IAG has accepted the establishment of the IHRF Computation Center (IHRF-CC) as a central coordinating body under the responsibility of the International Gravity Field Service (IGFS) with direct adherence to the IGFS Central Bureau (IGFS CB), composed of individual modules taking care of the main components of the IHRF. These modules are the IHRF Reference Network Coordination, the IHRF Conventions’ Coordination, the IHRF Associate Analysis Centers, and the IHRF Combination Coordination. In this work we outline the main components of the IHRF-CC, the objectives and goals foreseen, the main responsibilities of its component as well as their planned interrelation, complementarity and synergies in order to deliver its main products. The latter refer to the IHRS standards and conventions and their update; the update of the IHRF network and status; the IHRF computation cookbook; computation of offsets to national and regional vertical datums; and finally, IHRF station coordinates for the global core network and contributions to regional and national densifications. Finaly, we outline the first steps taken to formulate the IHRF-CC components and initiatives to begin normal operation.
Diagnostics of Northern Hemisphere blocking as simulated by Korean Integrated Model (KIM)
Authors: Cho Keon-Hee , Lee Eun-Hee
Published: March 2024

Blocking is one of the important meteorological phenomena that triggers severe weather in mid-latitudes. The blocking is considered a significant challenge in model predictions, and various studies have been conducted to enhance model predictability of blocking. For these reasons, this study aims to diagnose blocking using the KIM, discuss errors caused by blocking, and utilize it for further analysis. The method used to detect blocking involved the reversal method, considering conditions lasting for more than 5 days. We classified blocking into two types based on the direction of Rossby-Wave Breaking (RWB) during the sustained period. It was found that the classified blocking exhibits different impacts and areas of mid-latitude severe weathers. The distinction for the impacted areas of blocking based on the RWB enabled the definition of the influenced area for the classified blocking. Using this approach, we diagnosed patterns of errors observed in various experiments through the KIM.
Millennial scale monsoon variability over the last 250,000 years in the Arabian Sea
Authors: Lückge Andreas , Hollstein Martina , Mohtadi Mahyar , Schefuß Enno , Steinke Stephan
Published: March 2024

Dansgaard-Oeschger oscillations and Heinrich events described in Greenland ice cores are also visible in the climate of the monsoon realm as documented in Arabian Sea sediments. However, little is known about these millennial scale fluctuations beyond the reach of the Greenland ice cores. Here, we present high-resolution geochemical and micropaleontological data from two sediment cores located offshore Pakistan, extending the monsoon record to the past 250,000 years in millennial scale resolution.The stable oxygen isotope (d18O) record of the planktic foraminifera G. ruber shows a strong correspondence to Greenland ice core d18O, whereas the d18O signal of benthic foraminifera (U. peregrina and G. affinis) reflects patterns similar to those observed in Antarctic ice core records. Distinct shifts in benthic d18O during stadials are interpreted to show frequent injections of oxygen-rich intermediate water masses of Southern Ocean origin into the Arabian Sea. Alkenone SSTs show variations between 23 and 28°C. Millennial scale SST changes of 2°C are modulated by long-term SST fluctuations. Interstadials and the cold phases of interglacials are characterized by sediments enriched in organic carbon (TOC) whereas sediments with low TOC contents appear during stadials. Abrupt shifts (50-60 year duration) at climate transitions, such as interstadial inceptions, correlate with changes in productivity-related and anoxia-indicating proxies. Interstadial inorganic data consistently show that enhanced fluxes of terrestrial-derived sediments are paralleled by productivity maxima, and are characterized by an increased fluvial contribution from the Indus River. The hydrogen isotopic composition of terrigenous plant waxes indicates that stadials are dry phases whereas humid conditions seem to have prevailed during interstadials. In contrast, stadials are characterized by an increased contribution of aeolian dust probably from the Arabian Peninsula. Heinrich events are especially dry and dusty, indicating a dramatically weakened Indian summer monsoon and increased continental aridity.These results strengthen the evidence that North Atlantic temperature changes and shifts in the hydrological cycle of the Indian monsoon system are closely coupled, and had a massive impact on regional environmental conditions such as river discharge and ocean margin anoxia. These shifts were modulated by changes in the supply of water masses from the Southern Hemisphere.
Effects of dust source change, weathering and pedogenesis on loess sediments revealed by combined magnetic and geochemical studies – opportunities and challenges
Authors: Jordanova Diana , Jordanova Neli
Published: March 2024

Loess paleosol sequences carry valuable information on global climate change during the Quaternary. The main geochemical paleoenvironmental proxies rely on the well established sequence of mineral weathering and its products under earth surface conditions. On the other hand, mineral magnetic signal of the loess – paleosol sequences represent easily measurable and sensitive tool for identification and semi-quantification of the degree of secondary alterations of the initial loess substrate. We have analyzed geochemical and magnetic properties of a collection of loess – paleosol sediments from North Bulgaria from 8 profiles, spanning the time interval of the last 800 kyrs. Weathering indices calculated from the bulk geochemical data on major oxides indicate that loess samples are characterized by wide range of Chemical Index of Alteration (CIA) values – from 57.8 to 83.5 with the highest values typically obtained in the oldest deposits, formed during marine oxygen isotope stages (MIS) 16 and 18.  On the other hand, CIA values for paleosols are restricted in the range 73.4 – 82, indicating an intermediate weathering degree. Classic ternary A-CN-K diagram implies dominant role of plagioclase weathering. Magnetic signature of the studied collection shows typical widely observed magnetic enhancement in paleosols as compared to weakly magnetic non weathered loess material. The content of ultra fine grained superparamagnetic magnetite/maghemite give rise to the percent frequency dependent magnetic susceptibility, which shows linear relationship with CIA values, proving the genetic linkage between weathering and pedogenic magnetic fraction. On the other hand, calculated background magnetic susceptibilities χbg for the loess-paleosol couplets included in the study show reverse linear relationship with CIA values for the loess samples. Searching for possible effect of changing dust source areas, we observe decreasing χbg for sites located progressively eastward (longitudes varying from 23oE to 29oE) along with linear increase of χbg with increasing Cr/V ratio, indicative for increasing contribution of mafic component. At the same time, samples from loess horizons with the lowest χbg are characterized by the highest Al2O3/SiO2 values, e.g clay content. Thus, decreasing χbg along W – E transect probably reflects combined effects of dust source change and grain size fining during aeolian dust transportation. The relationships between CIA, χbg and pedogenic magnetic signatures suggest that aeolian dust material was already weathered before its deposition. As a result, the following periods of paleosol formation during interglacial epochs occurred under supply – limited weathering regimes.This contribution is supported by project No KP-06-H34/2 of the Bulgarian National Science Fund
Geochemical and microbiological signatures in the Vega Verde carbonate system, Botijuela, Puna Argentina.
Authors: Stepanenko Tatiana , Alonso Guido , Bahniuk Anelize , Cury Leonardo
Published: March 2024

      Botijuela travertine system is located at the western edge of the Salar de Antofalla at 3433 meters above sea level, the area shows several hot springs still active and several fossilized carbonate deposits. One of the main outcrops of this area is Vega Verde, which develops in a north-south direction where the carbonate deposits start from a vent and reach the Salar de Antofalla basin. In this place, it was possible to observe the development of several microbial ecosystems: non-lithified and lithified microbial mats in the closest area to the vent, as well as cyanobacterial biofilms and lithified stromatolites in the mixing zone between freshwater and thalassic water. In this work, we present the geochemical and mineralogical characterization of these microbial ecosystems. Mineralogically, the lithified ecosystems were composed mainly of calcite, and a less extended Mg-bearing calcite, aragonite, gypsum, and halite. Stable Isotopes C & O analyses showed that the samples from the vent presented an isotopic signature related to hydrothermal origin with δ13C (2,05 – 7,82) and δ18O (-6,59- -9,77) values. While the stromatolite from the Salar de Antofalla (in the mixing zone) showed high δ18O (0,8-1,12) and δ13C (7,63-13,26) values, which suggests that the evaporation process is the main fractionation force.   Although is considered that the main processes driving the travertine mineral precipitation are degassing and evaporation, petrological and SEM analyses showed that microbial activity appears to be contributing to the sedimentological textures of Vega Verde samples rocks. Moreover, the mineral morphologies and carbonate growth structures found in the SEM rock samples were also found in the in vitro carbonate precipitation experiments, but exclusively when microbial mats were present, and not in the negative control. These results suggest a strong influence of hydrothermal flows, evaporation process, and microbiological mediation during the Vega Verde carbonate systems formation.
Estimation of unsaturated hydraulic conductivity from morphological analysis of Xray-CT images
Authors: Ritschel Thomas
Published: March 2024

Water flow in the vadose zone is strongly non-linear due to the feedback of water flow, saturation, and the associated hydraulic conductivity. Therefore, the simulation of unsaturated flow at the continuum scale is notoriously complicated. Yet, not only the solution of the non-linear partial differential equation itself is difficult, also the appropriate parameterization of the unsaturated hydraulic conductivity function poses a challenge. Frequently, hydraulic conductivity is estimated from the water retention curve using capillary bundle models such as the well-established Mualem model or from pedotransfer functions that hardly include information on the actual pore space morphology. Here, a novel approach is presented to estimate the full unsaturated hydraulic conductivity function from a morphological analysis of Xray-CT images in the following way. First, the local pore space morphology is evaluated to obtain pore radius, Euclidean distances to the pore wall, and connectivity measures. Then, a local hydraulic conductivity and capillary forces are calculated for individual voxels of the images. This already permits to estimate the water retention curve and the water distribution inside the pore space at different levels of saturation. These configurations are then used to calculate an associated continuum scale hydraulic conductivity from dry to fully saturated conditions. This approach can be implemented in image analysis software, e.g. ImageJ, in a straight-forward way and may provide much better and specific estimates of the unsaturated hydraulic conductivity that sensitively affects the simulation of fluid flow in soils and the vadose zone provided satisfactory pore space acquisition with Xray-CT is possible.
The Atlantic Jet and European Hydroclimate Extremes During the Past 600 Years
Authors: Bronnimann Stefan , Franke Jörg , Valler Veronika , Hand Ralf , Samakinwa Eric , Lindstad Elin , Burgdorf Angela-Maria , Lipfert Laura
Published: March 2024

The jet stream over the Atlantic-European sector is relevant for weather and climate in Europe. It generates temperature extremes, steers moisture and flood-propelling weather systems to Europe or allows blocks to develop and persist leading to drought. Climate change might alter the jet characteristics affecting weather extremes. However, little is known about its interannual-to-decadal variability in the past. In this contribution we present an analysis of strength, tilt, and latitude of the Atlantic-European jet during the past 600 years in a comprehensive monthly climate reconstruction and compare their variability with drought and flood reconstructions in Europe. Summer drought is enhanced in Central Europe in periods with a poleward-shifted jet. An analysis of decadal flood variability shows that flood-rich periods in the warm season in the Alps coincide with an equatorward-shifted jet. In the cold season, a strong jet increases precipitation in Northern Europe, whereas an equatorward-shifted jet leads to frequent floods in Western Europe. Jet position, tilt, and strength are significantly influenced by El Niño and volcanic eruptions, but overall, the forced component is weak. The jet characteristics provide both a mechanism and a diagnostic to analyse decadal hydroclimate variability in Europe. Our 600-year perspective shows that recent changes in the jet are still within the past variability when considering ensemble members separately.  
Lightning-Ionosphere Interactions: An Accurate, Simplified Nighttime Mesospheric Photochemistry Model
Authors: Moore Robert , Santos Joshua
Published: March 2024

Lightning-ionosphere interactions are well documented in the form of observations of fantastic optical emissions such as sprites and elves.  In order to better understand electromagnetic heating of the lower ionosphere (∼60-100 km altitude), a mesospheric photo-chemistry model is employed to interpret lightning-ionosphere interactions. The LIMA atmospheric chemistry model implements >150 chemical reactions, as do similar atmospheric chemistry models, such as WACCM, but the LIMA model has had success modeling so-called Long Recovery Events. Due to the large number of reactions and chemical species involved, however, it can be difficult to identify specific cause and effect mechanisms for the event of interest. This paper presents a simplified mesospheric chemistry model that accurately reproduces lightning-ionosphere interactions predicted by the full 167-reaction LIMA model (it maintains the accuracy of the full LIMA model for electron density, electron temperature, electrical conductivity, and electromagnetic field intensity as a function of time and space throughout the heating process).
Multidecadal meridional dipole mode in the Indian Ocean subsurface ocean heat content
Authors: Amere Anand Babu , Dash Mihir Kumar , Senapati Balaji
Published: March 2024

Multidecadal changes in the background state of the Indian Ocean, such as variations in ocean circulation patterns, sea level and heat storage, can act as a carrier wave for the climate change and other variabilities. The long-term (~60 years since 1958) analysis of subsurface ocean heat content (sub-OHC) in the Indian Ocean exhibits the presence of a dominant multidecadal meridional dipole mode in the region. The analysis shows that until the late 1980s, a basin-wide meridional dipole mode is present, followed by the mode embedded in uniform basin-wide patterns. The trends of thermocline depth and sea surface height also exhibit the similar patterns. It is found that two distinct mechanisms are account for the observed patters in the Indian Ocean. Firstly, Local wind forcing is responsible for the meridional dipole patterns. In the off-equatorial southern Indian Ocean region, wind stress and Ekman pumping velocity trends favor downwelling (upwelling), resulting in thermocline depth deepening (shallowing) during 1958-1975 and 1976-1987, respectively. Secondly, the observed basin-wide warming and cooling trends during 1988-2000 and 2001-2014 are explained by the combined effect of local wind forcing and heat transport from the western Pacific through the Indonesian throughflow.
Tsunami databases in the eastern Mediterranean as new EPOS services
Authors: Papadopoulos Gerasimos , Triantafyllou Ioanna
Published: March 2024

The European Plate Observing System (EPOS) provides research infrastructure, including data and services, in solid Earth science. Recently EPOS decided also to create a Tsunami Core Service (TCS). In addition to the existing databases, we contribute to the TCS initiative by providing two new tsunami databases in the eastern Mediterranean as new EPOS services. The first database compiles data on Tsunami Observation Points (TOPs) of past tsunamis.  For a specific tsunami event the TOPs DB includes the source epicenter, the TOPs names and the corresponding geographical coordinates, names of the localities and a characterization of the tsunami intensity level, K, in each TOP. The second database compiles data on the impact of past tsunamis. Depending on the data availability an effort has been made to introduce quantitative impact data to the extent it is possible (e.g., numbers of fatalities and injuries, numbers of buildings or vessels damaged, etc.). From the impact of a tsunami event the maximum tsunami intensity, K, has been estimated according to the 12-grade scale of Papadopoulos and Imamura (2001). The new service is of great importance since it may help in studies of several kinds such as understanding better of the tsunami source type, determination of the inundation area, verification of tsunami simulation results and tsunami risk assessment.  