bluuebunny/crossref_metadata_2025 huggingface dataset:
Revisiting the relationship between the North Pacific decadal variability and the Kuroshio Extension bimodality
Authors: Wang Qiang
Published: March 2024

The Kuroshio Extension (KE) bimodality has important effects on the ocean environment, ecosystem and climate. Previous studies have revealed that the Kuroshio Extension (KE) bimodality is mainly determined by the westward-propagating Rossby wave triggered by the North Pacific decadal variability such as PDO or NPGO: the positive (negative) phase of NPGO corresponds to the stable (unstable) KE state. However, the KE state and the NPGO seem to be decoupled since 2017, during which the NPGO takes a negative phase but the KE is in a stable state. This study employs the Convergent Cross Mapping (CCM) method to investigate the causality between the KE bimodality and NPGO. Simultaneously, we divide the KE region into the upstream (west of 146°E) and downstream regions. It is found that the NPGO has a significant causal impact on the downstream KE state. But the effect on the upstream KE state significantly weakens around 2017. Further analysis indicates that the upstream KE state is mainly caused by eddy activity in the Kuroshio large meander region south of Japan. In particular, the changes in the eddy activity affect the downstream advection of eddies and induce changes in the Kuroshio position over the Izu ridge, which cause different states in the KE upstream region. Therefore, we should not only consider the NPGO change, but also the eddy activity change in the Kuroshio region south of Japan when understanding and predicting the KE low-frequency variability.
Wave-Convection Interactions Amplify Convective Parameterization Biases in the South Pacific Convergence Zone
Authors: Chen Yuanrui , Chu Wenchao , Wright Jonathon , Lin Yanluan
Published: March 2024

Climate models have long struggled to realistically simulate the South Pacific Convergence Zone (SPCZ) and its variability. For example, the default Zhang-McFarlane (ZM) convection in the Community Atmosphere Model version 5 (CAM5) produces too much light precipitation and too little heavy precipitation in the SPCZ, with this bias even more pronounced in the SPCZ region than in the broader tropics. In this presentation, we show that implementing a recently developed convection scheme in the CAM5 yields significant improvements in the simulated SPCZ during austral summer and describe the main reasons behind these improvements. In addition to intensifying both mean rainfall and its variability in the SPCZ, the new scheme produces a larger heavy rainfall fraction that is more consistent with observations and a state-of-the-art reanalysis. This shift toward heavier, more variable rainfall amounts is linked to increases in both the magnitude and altitude of diabatic heating associated with convective precipitation, thereby intensifying lower tropospheric convergence along the SPCZ axis and increasing the extent to which convection influences the upper-level circulation. Increased diabatic production of potential vorticity in the upper troposphere increases the distortion effect exerted by convection on transient Rossby waves passing through the SPCZ region. The much weaker distortion effects in simulations using the ZM scheme mean that waves are more likely to propagate continuously through the region rather than dissipate locally, thereby reducing updrafts and weakening convection within the SPCZ. Our results outline a dynamical framework for evaluating model representations of tropical-extratropical interactions within the SPCZ region and clarify why convective parameterizations that produce a more realistic top-heavy profile of deep convective heating are beneficial to representing the SPCZ and its variability.
Is PREMA exclusively associated with LLSVPs?
Authors: Liu Jingao , Cai Ronghua , Pearson Graham , Giuliani Andrea , van Keken Peter , Oesch Senan
Published: March 2024

Studies of ocean island basalts (OIBs) have identified a “Prevalent Mantle” component (or PREMA) that appears to represent one of the fundamental constituents of Earth’s mantle. Recent documentation of this signature in deep-sourced kimberlitic magmatism has increasingly linked PREMA with thermochemical structures above the core mantle boundary (LLSVPs). Yet, kimberlites provide geographically limited sampling of Earth’s mantle, which makes it difficult to identify the spatial association between LLSVPs and the PREMA component sampled by these magmas. To further investigate the global distribution of the PREMA mantle component, we utilize a much more widespread class of mantle-derived magmatism – global Cenozoic alkali basalts, nephelinites and basanites (‘sodic basalts’ hereafter) – that are derived from both continental and oceanic settings. Statistical treatment of the available ~3500 geochemical and isotopic analyses of Cenozoic sodic basalts worldwide shows that at low degrees of melting these magmas exhibit similar Sr-Nd-Hf isotopic characteristics to PREMA. There is no apparent spatial relationship between the distribution of PREMA-like sodic basalts and LLSVPs, implying that the PREMA component is not exclusively associated with LLSVPs. The PREMA-like signature of low-degree sodic basalts occurs in both OIBs and continental magmas, negating an exclusive link to continental lithosphere. Geochemical modelling and mantle convection simulations indicate that PREMA could have been generated soon after Earth accretion, experiencing only minimal melting or enrichment, and then scattered throughout the mantle, including the upper mantle, rather than being the result of mixing between depleted and enriched mantle components. This work indicates that PREMA probably represent a widespread fusible component that can be mingled with other components at various scales to generate all types of mantle magmatism.
Investigating Cloud Microphysical Properties: A Comprehensive Study Using High-Resolution Numerical Simulations and Observations in the Indian Ocean Region
Authors: El Gdachi Samira , Tulet Pierre , Rechou Anne , Burnet Frederic , Leriche Maud
Published: March 2024

 Located at 21°07'S, 55°32'E, Reunion Island, a mountainous island in the Indian Ocean, is an extraordinary site for studying the formation and life cycle of slope clouds. The island is influenced by southeast trade winds, reaching peak intensity in winter (June-August) and moderating during summer (December to February). These winds create pronounced conditions along the southwest and northeast edges, accompanied by a leeward circulation in the northwest, notably in the Maïdo area. Sea and valley breezes converge on the slopes of Maïdo, facilitating the advection of oceanic air masses and initiating convection on the mountainous terrain. Duflot et al. (2019) have substantiated that this convective process leads to the daily formation of clouds, typically exhibiting shallow vertical development and containing minimal water content.An intensive measurement campaign, BIOMAÏDO (Bio-physicochemistry of Tropical Clouds at Maïdo), took place from March 11 to April 7, 2019, at Reunion Island, in order to study the chemical and biological composition of the air mass, the formation processes of secondary organic matter in heterogeneous environments, the dynamics and evolution of the boundary layer, and the macro- and micro-physical properties of clouds.In this study, cloud microphysical properties are examined and analyzed using observations from the campaign, followed by a comparison with a high-resolution (100m horizontal resolution) numerical simulation with the Meso-NH model. Among the two microphysical schemes (ICE3 and LIMA; Liquid Ice Multiple Aerosol), the model is initialized with the two-moment microphysical scheme LIMA, which is parameterized using aerosol CCN properties initialization derived from ground aerosol measurements (3 modes) and vertical balloon profile aerosol concentrations.Firstly, a sensitivity study on the microphysical scheme will be presented. It demonstrates that clouds form simultaneously in both schemes. However, clouds exhibit greater vertical development in the ICE3 scheme. Additionally, cloud dissipation occurs an hour earlier in the LIMA scheme.Subsequently, an analysis through a microphysical variable balance will be conducted to identify the primary thermodynamic processes characterizing the formation and dissipation of slope clouds.
Large-Eddy Simulations of the Isotopic Signatures of Arctic Mixed-Phase Stratocumulus Clouds Under Different Surface and Atmospheric Conditions
Authors: Hu Zizhan , Wright Jonathon
Published: March 2024

Mixed-phase stratocumulus clouds in the polar region affect high-latitude climate in many ways, not least by regulating the boundary layer moisture and energy budgets. Sea ice coverage and thickness are decreasing sharply under global warming, changing the characteristics of the surface underlying much of the polar boundary layer, and the circulation patterns that govern lower tropospheric temperature and humidity inversions may change as well. Given the strength of ocean-ice-atmosphere interactions in the polar boundary layer, it is imperative to understand how different surface and atmospheric inversion conditions affect cloud formation and characteristics from both microphysical and macrophysical perspectives. Stable water isotopes have excellent potential as a tool to study the water cycle in the polar boundary layer, but their applications to understanding mixed-phase clouds in the polar region are limited by the lack of both direct observations and isotope-enabled models at appropriate spatial and temporal scales. Recent observational campaigns such as MOSAiC have observed isotopic composition at and near the Arctic surface under a range of different conditions, creating opportunities to expand the use of isotopes in Arctic water cycle research. Previous research has also established the ability of large-eddy simulations (LESs) to explicitly resolve boundary layer processes in the Arctic region and simulate the sensitivity of Arctic clouds to different atmospheric and surface conditions. To better exploit the potential of recent isotopic observations, we have developed an isotope-enabled large eddy model based on the PyCLES (Python Cloud Large Eddy Simulation) model framework to close some of the gaps between observations and modeling in the study of polar boundary layer clouds. iPyCLES is equipped with a two-moment microphysics scheme and includes representations of all essential isotopic fractionation processes at the surface and within clouds. In this presentation, we briefly introduce a series of sensitivity experiments targeting different surface and tropospheric inversion conditions to evaluate the isotopic signatures of surface-ice-atmosphere interactions within the polar boundary layer. The simulations are based on two well-studied field campaigns conducted near Barrow, Alaska, one in spring and one in autumn. Together with standard metrics of cloud evolution and turbulence mixing, isotope ratios in water vapor, cloud liquid and ice, and snow are tracked during the simulation. Isotopic signatures of each experiment are evaluated for their potential to provide observable constraints on polar clouds and boundary layer processes.
New insights of the Heinrich events inferred by speleothems from Northeast Brazil
Authors: Zhang Haiwei , Cheng Hai , Cruz Francisco W. , Auler Augusto S. , Spötl Christoph , Wang Xianfeng , Stríkis Nicolás M. , Zong Baoyun , Edwards R. Lawrence
Published: March 2024

Heinrich events (HEs), characterized by massive and rapid ice-rafted debris from Laurentide Ice Sheet into the Labrador Sea as far south as the Iberian Margin, are observed in some stadial periods during the last glacial, however, it is still unclear regarding to the trigger and response mechanism of the HEs. A landmark work by Wang et al. (2004) was one of the first studies to associate tropical rainfall in southern Hemisphere with HEs, showing wet periods in tropical northeastern Brazil, a region that is currently semi-arid but very sensitive to the hydroclimate changes related to the cold events occurred in the northern Hemisphere, are synchronous with HEs in the North Atlantic. After two decades, we have a new chance to study the relationship between hydroclimate in NE Brazil and cold events in the North Atlantic in the light of much more new speleothem records obtained from TBV and TBR caves, NE Brazil. Here we show evidence of stalagmite growth periods and δ18O records during the last 90 kyrs from NE Brazil, in addition to the HEs observed by Wang et al. (2004), we have newly found wet periods during the HE2 and HE3 and GS 5-8 that were not discovered before. It indicates that previous conclusions that the orbital insolation also modulated these events on millennial timescales need to be reinterpreted, and also provides new insights to understand the mechanisms of the HEs and why the HEs only occurred in some Heinrich Stadials. Additionally, we also compare detailed structures of each HE inferred from cave δ18O records in NE Brazil with sea surface temperature and other records in the Atlantic realm, which deepens our understanding of the trigger-response mechanisms of the HEs and its effect on the hydroclimate in the NE Brazil.
The Southern Ocean’s role in the global carbon cycle over the last 800 kyr constrained using reconstructions of the CO2 system
Authors: Xu Chen , Crumpton-Banks Jessica , Shankle Madison , Pelly Megan , Jurikova Hana , Yu Jimin , Opdyke Bradley , Hillenbrand Claus-Dieter , Burke Andrea , Rae James
Published: March 2024

The critical role of the Southern Ocean in controlling the Pleistocene atmospheric CO2 oscillations is widely acknowledged. However, owing to sampling difficulties surrounding Antarctica, the underlying mechanism and associated pathway of ocean-atmosphere CO2 exchange in the Antarctic Zone (AZ) of the Southern Ocean remains mysterious. Here, we present a new planktonic δ11B record from sediment core PS1506 (68.73°S, 5.85°W) that tracks the pH and surface pCO2 of the AZ over the last 8 glacial cycles. These data are complemented by benthic B/Ca and carbonate preservation indices; due to the location of this core on the continental margin of the eastern Weddell Sea, these data allow us to track the source CO2 chemistry of the dense Antarctic waters that feed the ocean’s lower overturing cell. We find coherent CO2 change between surface and deep waters, indicating persistent formation of AABW that transfers Antarctic surface water signals to depth. Critically, we discover abrupt AZ CO2 decline during glacial onset conditions, coinciding with initial atmospheric CO2 drawdown, highlighting the AZ’s key control on glacial-interglacial CO2 change. After assessing proposed drivers, our findings implicate shifts in Southern Ocean circulation linked to changes in sea ice and/or the Southern Hemisphere westerlies in this glacial onset CO2 change, while productivity, solubility, and sea ice 'lid' effects appear insignificant or counterproductive in this region and time interval. Overall, these reconstructed CO2 system dynamics provide critical insights into Southern Ocean carbon cycling and the associated influence on the atmosphere.
The Regional Impact of Ecological Restoration in the Arid Steppe on Dust Reduction over the Metropolitan Area in Northeastern China
Authors: Zhou Chaowei , Feng Xiaoming
Published: March 2024

A massive ecological restoration program has been implemented in northern China with the aim of protecting the Beijing-Tianjin-Hebei the metropolitan area of eastern China from dust events. However, some current studies have cast doubt on the efficacy of such ecological restoration projects, partly due to the constraint of available water in northern China, leading to poor survival rates of planted trees in semiarid regions (15%). In this study, using a logical framework combining statistical analysis, partial least-squares path model analysis, and a regional climate model (RegCM) simulation with multisource dust indicators, we found that there was a reduction of dust in northern China that was synchronous with the increase in vegetation growth after ecological restoration. In contrast to previous reports of a decrease in wind speed due to ecological restoration, this study found that the increase in vegetation had an insignificant impact on local wind speed (p = 0.30). Instead, ecological restoration mainly reduced the sand emission in the steppe areas by improving the soil conditions of the underlying surface and hence contributed 15% of the reduction of dust events in the BeijingTianjin-Hebei metropolitan area through dust transmission (p = 0.002). The effect of ecological restoration in the northern steppe on dust reduction in the northeastern metropolitan area of China should not be overstated.
A study of differences in PM2.5 concentrations at similar synoptic meteorological fields during the seasonal PM2.5 management from 2015 to 2019
Authors: Chae Daeun , Kim Jiseon , Yoo Jung-Woo , Lee Soon-Hwan
Published: March 2024

Due to rapid urbanization and population growth, high aerosol pollution in the Korean Peninsula has become a major environmental concern. High concentrations of PM2.5 in atmosphere is not only highly hazardous to humans, but also contributes significantly to visibility degradation and climate change. In study, K-means clustering analysis was performed to classify major synoptic patterns on the Korean Peninsula during the seasonal PM2.5 management from 2015 to 2019. Also, we analyzed synoptic patterns according to the air quality on each cluster by dividing the PM2.5 pollution standard into four levels to identify the differences in the occurrence of PM2.5 concentrations in the similar meteorological environment. As a result, the synoptic patterns were classified into five clusters (C1~C5). The clusters (C1, C3, C4) with pressure gradient from east to west showed differences of PM2.5 concentrations in Seoul as the pressure gradient between east and west changed. The clusters (C2, C5) with pressure gradients from south to north had different PM2.5 concentrations in Seoul depending on the location and intensity of high pressure located in southeast of the Korean Peninsula and the intensity and location of high- and low-pressure systems located in the North Pacific and Kamchatka Peninsula, respectively. This study confirmed that air quality can vary depending on the location and strength of high- and low-pressure systems in the similar synoptic meteorological environment.
On solving the nonlinear geodetic boundary value problem using mapped infinite elements
Authors: Minarechová Zuzana , Macák Marek , Čunderlík Róbert , Mikula Karol
Published: March 2024

The numerical approach for solving the nonlinear geodetic boundary value problem based on the finite element method with mapped infinite elements and itterative procedure is developed and implemented. In this approach, the 3D semi-infinite domain outside the Earth is bounded only by the triangular discretization of the whole Earth's surface and extends to infinity. Then the BVP consists of the Laplace equation for unknown disturbing potential which holds in the domain, the nonlinear boundary condition given directly at computational nodes on the Earth's surface, and regularity of the disturbing potential at infinity. In experiments, a convergence of the proposed numerical scheme to the exact solution is tested and then the numerical study is focused on a reconstruction of the harmonic function above the Earth's topography.
Cold Atom Interferometry Accelerometers for Future Satellite Gravity Missions
Authors: Knabe Annike , Schilling Manuel , Romeshkani Mohsen , HosseiniArani Alireza , Fletling Nina , Kupriyanov Alexey , Müller Jürgen , Beaufils Quentin , Pereira dos Santos Franck
Published: March 2024

Satellite gravity missions are a powerful tool to measure the global Earth’s gravity field and consequently provide important information for geosciences. However, improvements in spatial and temporal resolution are required for many applications. Simulation studies are performed to quantify the influence of improved sensors, orbit parameters and measurement concepts on the recovered gravity field solution. The investigations focus primarily on accelerometers by evaluating the concept of Cold Atom Interferometry (CAI) accelerometers and their combination with electrostatic accelerometers for future satellite gravity missions.The CAI noise behavior is mainly estimated based on the quantum projection noise, but also challenges due to the longer duration of the measurement cycle are investigated. The results of the low-low Satellite-to-Satellite Tracking (ll-SST) closed-loop simulations indicate, on the one hand, benefits from the addition of CAI and reveal, on the other hand, the dominance of background modeling errors. Furthermore, the combination of ll-SST and cross-track gradiometry is studied. In order to significantly benefit from an additional cross-track gradiometer, it has to achieve a low noise level of 1 mE and the angular velocity measurements have to ensure high accuracies.We acknowledge the support by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Project-ID 434617780 – SFB 1464 and under Germany’s Excellence Strategy – EXC-2123 Quantum-Frontiers – 390837967, the support by Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) for the project Q-BAGS and the European Union for the project CARIOQA-PMP (Project-ID 101081775).
Subduction thermal structure and megathrust earthquakes under the Mariana arc
Authors: Ji Yingfeng , Qu Rui , Zhu Weiling
Published: March 2024

Due to the steep subduction of a highly concave slab, researchers have characterized megathrusts under the Marianas as among the coldest and curviest plate coupling interfaces in various circum-Pacific subduction zones. Seismic tomography indicates that the heterogeneous underlying plate varies markedly in its subduction angle, velocity, and flexure along the strike and dip, while their effects on the thermal structure and intraslab earthquake occurrence remain enigmatic. By incorporating the 3-D MORVEL velocity and state-of-the-art slab geometry into thermomechanical modeling, we estimated the 3-D subduction thermal state and hydrothermal regime below the Marianas. We find that (1) the concave slab geometry and the complexity of the intraslab velocity variation in the Marianas are associated with a heterogeneous along-strike thermal regime and a cold mantle wedge beneath the central Marianas; (2) amphibolitization and eclogitization of subducted oceanic crust cause variations in fluid pressure and fluid release from the subduction interface, which may influence the distribution of interface seismicity in the Mariana system; (3) the concentration of active hydrothermal vents in the trench > 8 km deep is accompanied by a large temperature gradient and subsequent remarkable slab dehydration in the southern Marianas; and (4) slab dehydration (> 0.02 wt%/km) from 30 to 80 km indicates notable fluid release and potential fluid migration in subduction channels, which may correspond to the large water flux at depth beneath the Marianas.
Reconsidering hydropower in the African energy transition
Authors: Giuliani Matteo , Castelletti Andrea , Carlino Angelo , Arnold Wyatt
Published: March 2024

African nations are striving to meet increasing energy demands driven by population growth and improving living standards. To reduce emissions, many national capacity expansion plans are attempting to use low-carbon electricity sources and exploit the untapped continental hydropower potential with 300 new hydropower projects planned for a total of around 100 GW of new installed capacity. However, climate, socio-economic, and technological changes are making these investments in new dams more risky and less economically efficient.In this talk, we discuss the role of hydropower projects across different power capacity expansion pathways in Africa. Our multi-scale analysis is built on an integrated modeling framework that combines an Integrated Assessment Model (GCAM), an energy system planning model (OSeMOSYS-TEMBA), a power system model (PowNet), and a strategic river basin-scale reservoir system model. This framework allows the simulation of different future scenarios that harmonize global climate policies, land-use change, climate impacts on water availability, final energy demands, and multipurpose reservoir operations.Our results show that, depending on the scenario considered, between 32 and 60% of the proposed hydropower capacity is not cost-optimal. Moreover, our analysis suggests that hardly any new hydropower will be built after 2030, meaning that its role in terms of installed capacity and generation will gradually decrease in favor of solar and wind power. Besides, floating photovoltaics might also represent a low-impact alternative to hydroelectric dams, producing 20-100% of the electricity from planned hydroelectric dams depending on the scale of deployment of this new technology on existing hydroelectric infrastructure at the African power pool scale. Lastly, we show how policy fragmentation between developed and developing countries in their approach to land use change emissions can have negative side effects on local water demands, producing favorable conditions for the realization of extensive agricultural projects in Africa that increase local irrigation demands and constrain the availability of water resources for hydropower production.These findings show that strategic planning of water-energy systems is essential to navigate the complex landscape of hydropower development in Africa. By adopting a systemic approach, African nations can identify cost-efficient climate-resilient hydropower projects that will contribute in securing a sustainable and resilient energy future.
25 years recording of the long-base fluid tiltmeter installed at 2.850 m a.s.l. observatory on Etna volcano
Authors: Gambino Salvatore , Privitera Laura , Bonaccorso Alessandro , Falzone Giuseppe , Laudani Giuseppe , Ferro Angelo
Published: March 2024

Etna is a very active volcano with frequent eruptions and it is well controlled through different monitoring techniques. Continuous control of ground deformation is also provided by tilt measurements especially through a network of short-base borehole sensors. Since 1996 this network has been integrated with a long-base fluid tiltmeter installed in two 80 m long tunnels present at the high altitude (2,850 m a.s.l.) volcanological observatory of Pizzi Deneri (PDN) located on the summit area of the volcano. The instrumentation was created with an innovative configuration composed of mercury, free to move along the entire length of 80 m in response to the ground tilt, and laser sensors to measure the changes of the mercury level at the ends of the length where this fluid is positioned. In this study for the first time we present the entire set of 25 years of data (1997-2022) recorded by this instrumentation. During this long time interval, the Etna volcano was characterized by numerous main eruptions due to dyke intrusions. The tilt variations recorded in the short term during the rapid intrusive phases are presented and discussed. These signals contributed to the modeling of eruptive processes, and in particular in the case of the 2002-2003 eruption they contributed to the real-time understanding of the ongoing eruptive phenomenon, supporting the correct hazard assessment. In the medium-long term (years to decades) the signal maintained a trend that cumulated approximately 200 microrads on both components during the entire observation. PDN long term is primarily affected by the dynamics of the marked sliding of the entire eastern sector of the volcano.
Global soil carbon storage and stability informed by the particulate and mineral-associated organic carbon fractions
Authors: Chen Ji , Cotrufo M. Francesca , Sun Siyi
Published: March 2024

Separating soil organic carbon (SOC) into particulate (POC) and mineral-associated organic carbon (MAOC) fractions has provided fundamental knowledge on the structure and protection of SOC. However, the global distribution and key drivers of POC and MAOC remain elusive. Here, we compiled a global database of POC and MAOC with 2744 observations across six continents. Initial analysis showed that the mean POC was 2.73 kg m-2 and MAOC was 3.85 kg m-2 at 0-30 cm. At the global scale, POC and MAOC accounted for 39.98 % and 63.48 % of SOC, respectively. The global distribution of POC and MAOC was driven collectively by vegetation, climatic, and soil attributes. The lowest POC and MAOC stock were observed in cropland, suggesting the possibility of increasing C sequestration in soils by using management practices that increase POC and MAOC in croplands. Despite this great potential, we predicted the largest reduction in MAOC in cropland under future climate change, highlighting the high vulnerability of SOC stock in cropland. Understanding the role of environmental controls in the global distribution of POC and MAOC could help designing terrestrial carbon sequestration strategies.
Unconventional Gas Potential of Black Shales from Silurian Findikli Formation in northwestern Anatolia, Türkiye: Characterization of Geochemistry
Authors: Doner Zeynep
Published: March 2024

As conventional hydrocarbon resources become depleted and theoretical innovations in hydrocarbon exploration advance, unconventional resources have gained substantial attention from researchers and explorers in recent decades. In the global energy consumption structure, unconventional shale gas progressively assumes a crucial role in the overall energy landscape. This research is motivated by the high probability of deriving gas accumulations encountered in drilling on the northwestern Anatolia (Akcakoca area) offshore from Paleozoic-aged rocks. Studied black shales from the Silurian Findikli Formation in the Sakarya region of northwestern Anatolia are one of the alternative unconventional resources.Working with outcrop samples, this work evaluates the unconventional gas potential by performing geochemical characterization of these black shale samples. Studied samples were analyzed by Rock-Eval Pyrolysis. The present-day total organic carbon (TOCpd) contents range from 0.54 to 1.57 wt.%. High Tmax (up to 504oC) and low Hydrogen Index (HI) values (4-38 mg HC/g TOC) indicate that these shales are thermally over-mature and seem to be a spent hydrocarbon source rock. The remaining hydrocarbon generative potential (S1+S2) of 0.06–0.49 mg HC/g rock also supports this assessment. The recent organic matter type is Type IV kerogen which can yield limited gas products plotting on the H/C versus O/C atomic ratios on the modified Van Krevelen diagram. According to the interpretive of shale gas potential parameters based on Jarvie’s equation reconstructed these black shales originally may have good to very good source rock potential, with the calculated average original values of TOCo being 1.72 wt.% and HIo is 448 mg HC/g TOC. It can be concluded that the characteristics of studied shales seem to be nearly compatible with those of Utica shales in terms of the hydrocarbon generative potential. The studied black shales have lost 95% of their original hydrocarbon potentials, and seem to be a spent hydrocarbon source rock, indicating good risk for gas. However, the source rock may be very deep and deformed from the past to the present day, considering the paleogeographical location and geological evolution of the study area. Further research is required.Keywords: Unconventional Gas Potential, Source Rock, Geochemical Characteristics, Silurian Black Shales, Northwestern Anatolia (Türkiye)
Mechanical Models for East-West Extension within the Pamir Orogen: Insights from of the Holocene slip rate of the Kongur Normal Fault
Authors: Liu Qi , Chen Jie , Li Tao , Xu Jianhong , Di Ning , Luo Ming
Published: March 2024

The Pamir orogen, laying at the northwestern syntaxis of the Indo-Asian collision zone and one of the most tectonically active regions of central Asia, experiences significant extension in its interior. Although internal extension is common in mature orogens, the Pamir is special because (i) its extension is primarily concentrated on the Kongur Extensional System (KES) rather than distributed on multiple normal faults; (ii) the KES is localized at the eastern region of the Pamir rather than centralized, suggesting asymmetric extension; and (iii) extension along the KES decreases southward, instead of decreasing from central portion to its northern and southern ends. Because of these unique characteristics, the causes of internal extension of the Pamir and formation of the KES have inspired numerous investigations, which in turn have led to the proposal of various mechanical models. Defining multi-timescale deformation rates along the KES, especially for late Quaternary and modern slip rate, is prerequisite for better understanding the nature of extension in the Pamir.In this study, we focus on one of the most debated structure within the Pamir: the nearly NNW-trending Kongur Normal Fault (KNF), the most primary and striking part of the KES. This fault is characterized by dramatically increased topography (elevation up to > 7,500 m) which is expressed as lofty Kongur and Muztaghata massif in its footwall. Thermochronology ages suggest that the initiation, largest magnitude of extension and highest long-term exhumation rates along the KES are in the vicinity of the Kongur massif. Although some studies have focused on determining the tectonic activity of the KES since the late Cenozoic, almost no late Quaternary rates estimate yet exists on active fault (KNF) bounding the Kongur massif. Moreover, Glaciers have oscillated considerably throughout the Quaternary at Kongur and Muztaghata massif, offering a unique opportunity to expand our understanding of the role of glaciers in shaping the topography.At Bulunkou, the KNF is branched into two segment. The surface trace of the both segments of KNF is clearly visible as a straight line feature, and characterized by offsets of different geomorphic surfaces. We determined the Holocene slip rates of both segment of KNF through geomorphic mapping on high-resolution DEMs and cosmogenic 10Be exposure dating of boulders on displaced geomorphic surfaces. Finally, we observed a very high Holocene slip rates (even probably can reach to 10-13 mm/a) of KNF at Bulunkou. Correlating our new observations of KNF with kinematics and slip rates along the whole KES, we clarify the role of the KES in accommodating internal extension of the Pamir.
Modeling human migration: a minimalistic mechanistic modelling approach
Authors: Muneepeerakul Rachata
Published: March 2024

Migration is one of human’s most drastic adaptation strategies against unfavorable conditions. In this work, we developed a minimalistic mechanistic model for human migration, dubbed CHASE, is developed. The model is named after the factors it includes to capture human migration, namely CH = Changing mindset, A = Agglomeration, S = Social ties, and E = the Environment.  Numerical experiments were conducted by subjecting the human agents in the model to two different kinds of disturbances: sudden shocks and gradual changes. Model results revealed highly nonlinear interplay among diversity, distance barrier, and social ties. The results also showed distinct responses to sudden shocks and gradual changes, both in terms of dynamics of the populations and diversity patterns.  Some ongoing and future work will also be briefly discussed.
Flume tests and rheological experiments provide insights into the fluidization of bed material induced by shear thinning during the entrainment of rock avalanches.
Authors: Zheng Yangshuai , Hu Wei
Published: March 2024

In the realm of natural Earth-surface processes, such as mass movements exemplified by rock avalanches, a substantial entrainment of bed material along their trajectory is a common occurrence, amplifying both volume and run-out distance. The heightened mobility of these rapid gravity flows has been frequently ascribed by numerous researchers to the complete or partial fluidization of path material induced by swift undrained loading. An intriguing question arises: are there additional entrainment mechanisms at play in this process? To address this query, we executed a series of flume experiments designed to replicate rock avalanches overriding a saturated bed material. Our experimental findings revealed that the overriding flow induced a state of fluidization in the bed material, rendering it viscous. Furthermore, we observed that the rapid loading by the overriding debris increased pore pressure at the base, although it did not reach the threshold of complete fluidization. Rheological analysis of the bed material unveiled significant shear-thinning behavior, with viscosity diminishing rapidly as shear strain rate increased. Consequently, we posit that the concurrent effects of excess pore pressure at the basal layer and shear-thinning rheology in the flowing mass contributed to the fluidization of bed material and the ensuing extended run-out distance. This discovery offers a plausible natural elucidation for the extraordinary mobility of rock avalanches and holds promise for refining the precision and reliability of numerical simulations through the integration of the viscous model derived from our experimental endeavors.
Testing the predictive capability of the Index of Connectivity (IC) on a 2022 debris-flow event considering the spatial variability of the forcing
Authors: Himmelstoss Toni , Rom Jakob , Kara Diana-Eileen , Betz Sarah , Altmann Moritz , Haas Florian , Becht Michael , Heckmann Tobias
Published: March 2024

Sediment connectivity is an important property of geomorphic systems reflecting the potential to route material through themselves and hence modulating the propagation of geomorphic changes. While the relevance of the concept is clear, connectivity cannot be measured directly and the discussion on the best methods to quantify connectivity is still ongoing. Probably the most frequently used approach is based on the index of connectivity (IC) as it was developed by Borselli et al. (2008) and later adapted by Cavalli et al. (2013) for alpine catchments. This index aims at quantifying the structural connectivity that is governed by the spatial configuration and properties of system components. Nevertheless, the predictive capabilities of this index for functional connectivity, i.e. the actual transfer of sediment between the system components, have not been conclusively validated with field data. Most importantly, previous studies have, to our knowledge, not taken into account the spatial variability of the hydrometeorological forcing that leads to different functional connectivity in locations with similar structural connectivity.In this study, we use a unique dataset to test the predictive capability of the IC for hillslope-channel coupling of debris flows in the Horlachtal, Austria (described by Rom et al., 2023). The dataset consists of aerial imagery and two airborne LiDAR digital elevation models from which n=156 debris flows were mapped and quantified that were triggered by intense rainstorms on July 20th and 23rd, 2022. For this event, adjusted radar data (INCA data from the Austrian meteorological survey, ZAMG, and measurements from weather stations within the study area) give a high-resolution account of the spatial distribution of rainfall intensities and sums. Using these data, each debris flow was characterised with respect to (i) the meteorological forcing that affected its contributing area, (ii) morphometric properties of the latter, (iii) its sediment volume, and (iv) its runout length indicating functional connectivity, i.e. the degree of coupling to the main channel. Then we assessed the influence of structural connectivity (indicated by the IC) and hydrometeorological forcing on the observed functional connectivity. To our knowledge, this is the first study investigating the predictive capacity of the IC taking into account the spatial variability of the forcing. Among others, our results show that the IC is significantly higher for those debris flows that reached the main channel, compared to those that did not.
Impact of small-scale gravity waves on tracer transport
Authors: Knop Irmgard , Dolaptchiev Stamen , Achatz Ulrich
Published: March 2024

The zonal-mean transport of tracers on a large scale, such as ozone and water vapor, is predominantly governed by the Brewer-Dobson circulation. However, this transport undergoes modifications influenced by small-scale gravity waves (GW) and turbulence resulting from GW breaking. As these dynamics are not completely resolved in weather and climate models, they necessitate parameterization. Given the significant impact of tracers on the Earth's energy budget and surface climate, understanding their transport variations is crucial for accurate atmospheric modeling. Presently, existing GW parameterization schemes neither account for the direct effects of GW tracer transport nor the enhanced tracer mixing due to GW breaking, but only for the indirect effect by driving the mean meridional circulation. Therefore, it becomes imperative to ascertain how and to what extent these small-scale phenomena modify the large-scale transport of tracers. To address this, we employ wave-resolving simulations, specifically investigating the impact of a three-dimensional wavepacket on tracer distribution using a pseudo-incompressible flow solver. Additionally, we extend a GW parameterization scheme, a Lagrangian ray tracer, to incorporate GW-induced tracer transport. Our research demonstrates the non-negligible direct impact of GW on tracer transport. Furthermore, we possibly discuss the influence of turbulent diffusive mixing on tracers. Our aim is to provide a comprehensive understanding of the intricate processes shaping large-scale tracer transport in the atmosphere.
Addressing forest canopy decoupling in eddy covariance flux measurement networks
Authors: Jocher Georg , Kowalska Natalia , Liu Heping , Wharton Sonia , Montagnani Leonardo , Papale Dario
Published: March 2024

The eddy covariance (EC) method is the standard technique for determining forest ecosystem-atmosphere turbulent exchange, however, it encounters a significant challenge: the air masses below the canopy often become decoupled from the air masses above it. Consequently, the EC measurements of scalar fluxes (e.g. H2O and particularly CO2) above the canopy can be biased due to missing signals from below-canopy processes. This decoupling is strongly site dependent and influenced by atmospheric conditions, canopy properties and tower-surrounding topography. Multiple approaches have been developed in the recent decades to address decoupling (e.g. u* filtering, quality flags for flux measurements, storage change evaluations, direct advection measurements), however, all of them appeared to be insufficient to fully tackle the problem. A promising additional approach is based on subsequent EC measurements below and above the canopy. Specifically, examining the correlation of the standard deviation of vertical wind (obtained via sonic anemometers) below and above the canopy provides insight into the coupling state, as this correlation remains linear during fully coupled periods.To date, there is no standardized approach to address decoupling yet, hence, it is commonly not explicitly considered in EC measurement networks and infrastructures such as FLUXNET or ICOS (Integrated Carbon Observation System). A specialized working group within ICOS strives for addressing this by initiating an extensive multi-site experiment. This multi-site experiment aims to i) evaluate the performance of different types of sonic anemometers below canopy for decoupling investigations, ii) explore the spatial heterogeneity of below canopy processes in relation to decoupling, iii) develop a robust procedure to integrate decoupling investigations in the standard processing of EC measurement networks.The anticipated experimental design involves three testing sites chosen to represent a broad range of canopy characteristics. These sites consist of a deciduous broadleaf forest in flat terrain (Lanžhot, Czech Republic), a coniferous forest in mountainous terrain (Renon, Italy), and a tall evergreen needleleaf forest in moderately complex mountain-valley terrain (Wind River, USA). The working group, in collaboration with industry partners, plans to deploy approximately 30 sonic anemometers across these sites. While around 10 sonic anemometers of the same type will be installed at the Wind River site, the rest, comprising different types, will be set up at Lanžhot and Renon. Installations, arranged in an array below the canopy around the primary EC measurement tower, are scheduled to commence in spring 2024, with the goal of year-long data collection to cover all seasons.This presentation will set the proposed experiment on a solid theoretical background, introduce the measurement design and discuss the experiment aims.
Stability regimes and safe overshoots in West and East Antarctica
Authors: Klose Ann Kristin , Winkelmann Ricarda
Published: March 2024

Earth's climate will likely exceed a warming of 1.5°C in the coming decades. Maintaining such warming levels for a longer period of time may pose a considerable risk of crossing critical thresholds in Antarctica and, thereby, triggering self-sustained, potentially irreversible ice loss, even if the forcing is reduced in a temperature overshoot. Due to the complex interplay of several amplifying and dampening feedbacks at play in Antarctica, the duration and amplitude of such warming overshoots as well as their eventual 'landing' climate will determine the long-term evolution of the ice sheet.Using the Parallel Ice Sheet Model, we systematically test for the reversibility of committed large-scale ice-sheet changes triggered by warming projected over the next centuries, and thereby explore (1) the stability regimes of the Antarctic Ice Sheet and (2) the potential for safe overshoots of critical thresholds in Antarctica.We demonstrate crucial features of the Antarctic Ice Sheet's stability landscape for its long-term trajectory in response to future human actions: Given ice-sheet inertia, an early reversal of climate may allow for avoiding self-sustained ice loss that would otherwise be irreversible (for the same reduction in warming) due to multistability of the ice sheet at the basin- and continental scale. While we show that such safe overshoots of critical thresholds in Antarctica may be possible, it is also clear that limiting global warming is the only viable option to evade the risk of widespread ice loss in the long term.