bluuebunny/crossref_metadata_2025 huggingface dataset:
Triassic collision of the Qinling Orogen: Evidence from granulite metamorphism of the Foping gneiss dome
Authors: You Jiali , Yang Zhao
Published: March 2024

Triassic collisional assemblage between the North China Block (NCB) and South China Block (SCB) along the Qinling Orogen still remains controversy in timing and process. As an indicator, collision-type granulite well records textural evidences of orogenic crustal alteration induced by continental collision. Located at the narrowest part of the Qinling Orogen, the Foping gneiss dome exposed pelitic and mafic granulites, migmatite and granitoids, which are critical to understand the Triassic tectonic evolution history of the Qinling Orogen. Representative pelitic granulite, mafic granulite, and pelitic schist samples from the Foping dome were selected to obtain the P-T-t paths to reveal the collision timing and process, through an integrated study of petrography, mineral chemistry, estimation of P/T conditions and U-Pb geochronological dating. Our results indicate that these granulites experienced granulite facies peak metamorphism at 6.2-7.4 kbar/ 805-855 °C and followed by retrograde metamorphism at 3.4-4.7 kbar/ 605-715 °C with characteristic of clockwise P-T paths. The pelitic schist underwent peak and retrograde stages at P/T conditions of 4.9-5.1 kbar/ 590-605 °C and 3.5-3.7 kbar/ 510-520 °C, respectively, and consisting clockwise P-T paths. Zircon U-Pb dating gives an inherited age of ca.580-573 Ma, which indicates the protoliths of the Foping granulites probably derived from Neoproterozoic. In addition, it also generates a peak metamorphic age of ca.247-240 Ma, revealing the collision onset of the Qinling Orogen at Early-Middle Triassic. Integrated results of zircon and monazite U-Pb analyzing yield retrograde age at ca.208-198 Ma, constraining the collision termination at Late Triassic. Together with the previous studies in the Qinling-Dabie Orogen, we propose that the collision between the SCB and the NCB occurred in the Qinling Orogen, and it is coeval with the collision time of late Permian-Middle Triassic in the Dabie Orogen, and ends at ca.208-198 Ma. Then the > 70o main clockwise rotation occurred in Jurassic-Cretaceous probably.
Predicting Sulfide Precipitation in Magma Oceans on Earth, Mars, and the Moon Using Machine Learning
Authors: ZhangZhou Johnny , Li Yuan , Chowdhury Proteek , Sen Sayan , Ghosh Urmi , Xu Zheng , Liu Jingao , Wang Zaicong , Day James
Published: March 2024

The sulfur content at sulfide saturation (SCSS) in silicate melts plays a pivotal role in governing the behavior of chalcophile elements in planetary magma oceans. Numerous high-pressure experiments have been conducted to determine SCSS, employing various regression methods to capture the thermodynamic characteristics of the system. However, existing empirical equations have shown limited predictive accuracy when applied to laboratory measurements. In this study, we have compiled and analyzed 542 experimental datasets encompassing diverse sulfide and silicate compositions under varying pressure-temperature (P-T) conditions (up to 24 GPa and 2673 K). Employing empirical equations, linear regression, Random Forest algorithms, and a novel hybrid approach combining empirical fits for P-T conditions with Random Forest modeling for compositions, we have developed multiple SCSS models. These models have been rigorously compared with laboratory measurements. Our findings reveal that the Random Forest and hybrid models exhibit exceptional predictive performance (R2 = 0.82–0.91, mean average error [MAE] < 746 ppmw S, residual mean standard error [RMSE] < 972 ppmw S) in comparison to previous empirical models (R2 = 0.28–0.69, MAE = 622–1,170 ppmw S, RMSE = 1,070–1,744 ppmw S). Linear regression falls in between the performance of classical and machine learning models. Furthermore, we have applied our hybrid model to predict SCSS during the solidification of magma oceans on Earth, Mars, and the Moon. A comparison of our model results with expected sulfur contents in residual magma oceans, calculated through mass balance, offers valuable insights. Our analysis confirms that sulfides precipitated during the early accretion phases of Earth and Mars, but not on the Moon. Subsequently, evolving compositions of magma oceans offset increasing sulfur concentrations, preventing sulfide precipitation during intermediate stages of crystallization. Late-stage sulfide precipitation, contributing significantly to the bulk-silicate sulfur abundances of Earth, Mars, and the Moon, occurred at shallow depths (120–220 km, 40–320 km, and
Deciphering orbital-scale precipitation changes in the northern East Asian monsoon region: insights into the roles of terrestrial and oceanic moisture sources
Authors: Xie Xiaoxun , Liu Xiaodong
Published: March 2024

Water vapor is the essential substance for precipitation and a crucial component of the global hydrological cycle. Quantifying the contributions of terrestrial and oceanic moisture sources is crucial for comprehending regional precipitation and hydroclimate changes. Previous studies have extensively investigated the East Asian summer monsoon and its precipitation changes using geological climate records, but it remains unclear how water vapor from different source regions affects the orbital-scale precipitation change in East Asia. In this study, a long-term transient simulation using a water vapor tracking climate model was conducted for the past 300 kyr to investigate the contributions of terrestrial and oceanic moisture sources to precipitation changes in the northern East Asian monsoon region (NEA, 35-45°N, 105-120°E). The results showed that for the climatologically annual NEA precipitation, the global land source was the primary moisture source, accounting for approximately 57.6% of the total precipitation, followed by Pacific Ocean source contributing 20.9%, while other sources had a minor contribution. The orbital-scale changes of annual NEA precipitation, dominated by the precipitation of the rainy season from May to September, were mainly characterized by a significant 23-kyr cycle and a weak 100-kyr cycle. Analyses of water vapor sources found that the significant 23-kyr cycle in NEA precipitation was caused by the superposition of the synchronous 23-kyr cycles of precipitations from the land and Pacific Ocean sources, while the nonsynchronous 100-kyr cyclic changes of precipitations from the land and Pacific Ocean sources led to the weak 100-kyr cycle of NEA total precipitation. The dominant 23-kyr cycle of NEA precipitation reflects the effect of precession forcing, while the weak 100-kyr cycle implies the impact of the high-latitude ice sheet forcing, which triggers the antiphase change in the moisture contribution rates of the land and Pacific sources in the glacial-interglacial cycle. This study highlights the importance of terrestrial and oceanic moisture sources associated with external forcings in understanding the orbital-scale East Asian monsoon precipitation changes. As a preliminary attempt to track the orbital-scale variations of the terrestrial and oceanic moisture sources of East Asian monsoon precipitation by conducting a water vapor tracking transient simulation, this study provides new insights into the temporal-frequency characteristics and physical mechanisms of orbital-scale East Asian monsoon precipitation variations from the perspective of water vapor sources.
A Novel Backtracing Model to Study the Emission of Energetic Neutral Atoms at Titan
Authors: Tippens Tyler , Roussos Elias , Simon Sven , Liuzzo Lucas
Published: March 2024

To study the emission of energetic neutral atoms (ENAs) at Titan, we have developed a novel model that takes into account a spacecraft detector’s limited field of view and traces energetic magnetospheric particles backward in time. ENAs are generated by charge exchange between Titan’s atmospheric neutrals and energetic magnetospheric ions. By tracing these ions through the draped electromagnetic fields in Titan’s environment, we generate synthetic ENA images and compare them to Cassini observations from the TA flyby. Our model can reproduce the intensity and morphology of the observed images only when field line draping is included. Using a realistic detector geometry is necessary to determine the influence of this draping on the ENA images: the field perturbations eliminate a localized feature in the emission pattern, which is a different effect than found by previous models utilizing an infinitely extended detector. We demonstrate that ENA observations from TA contain signatures of the time-varying Saturnian magnetospheric environment at Titan: the modeled ENA emission morphology and the effect of field line draping are different for the background field vectors measured during the inbound and outbound legs of TA. The visibility and qualitative effect of the draping on observed ENA images vary strongly between different detector locations and pointings. Depending on the viewing geometry, field line draping may add features to the synthetic ENA images, remove features from them, or have no qualitative effect at all. Our study emphasizes the challenges and the potential for remote sensing of Titan’s interaction region using ENA imaging.
Snow depth variation and its relation with climate variability in China
Authors: Saydi Muattar , Tang Guoping , Ding Jianli , Wang Zhengang
Published: March 2024

Various climatic factors and their interactions affect alterations in China's snow depth. However, a measure of the relative importance of climatic factors regarding the variance in reginal snow depth is lacking. Here, we use a large dataset, quality-controlled daily observations from 1,665 meteorological stations, and statistical regression modelling to identify main drivers and their contributions regarding regional variability and trends in China's snow depth and snow depth-climate relationships from 1951 to 2019. Results show that seasonal snow depth alterations are substantial in China and caused by various climatic drivers. In winter, changes in snow depth across the northwest and northeast of China exhibit a more general increasing trend, while changes in snow depth across the Tibetan Plateau and the remaining regions of China show a more common decreasing trend. The observed positive trends in the northwest and northeast of China mainly respond to augmentation in solid precipitation, explaining nearly 60% of the total interannual variance, and snow accumulation in fall. For the Tibetan Plateau, the negative snow depth anomaly seems to respond to the rising air temperature below the freezing point along with some secular changes in solid precipitation and shallower fall snowpacks. All these trends in winter snow depth over the northwest, northeast, and Tibetan Plateau of China translate into the properties of spring snow depth, accounting approximately for 30% of the total interannual variance in spring snow depth in these regions. In the milder central north and south of China, snow accumulation is not evident. Besides solid precipitation and rising air temperature below the freezing point, atmospheric humidity is also notable for its effect on the interannual variance in winter snow depth in these regions. In spring, however, China's snow depth exhibits a general reduction. Particularly, the central north of China, has experienced the greatest reduction of nearly 50% in spring snow depth during the recent two decades. In fall, on the other hand, changes in snow depth are mostly insignificant in China, but the stronger signal of reduction mainly occurs on the Tibetan Plateau. Moreover, in spring and fall, the negative effect of warming climate on snow depth becomes remarkably more important. It seems that about 13–33% (12–50%) of the total interannual variance in the widespread decrease (insignificant perturbation) of China's spring (fall) snow depth are caused by the rising air temperature below the freezing point.
The Dominant Role of the Tibetan Plateau and the Antarctic in Establishing the Atlantic Meridional Overturning Circulation
Authors: Tong Mingjun , An Fengli , Yang Haijun
Published: March 2024

Our recent research underscores the pivotal roles of the Tibetan Plateau and Antarctica in the development of the Atlantic Meridional Overturning Circulation (AMOC). This study rigorously investigates how these two regions collectively influence the AMOC, using coupled model’s sensitive experiments that sequentially introduce the Tibetan Plateau followed by Antarctica (TP2AT), and then in the reverse order (AT2TP). The rise of the Tibetan Plateau markedly alters atmospheric moisture transport patterns in the Northern Hemisphere, leading to a fresher North Pacific and a saltier North Atlantic. This change is the key to shifting deep-water formation from the North Pacific to the North Atlantic, thereby initiating the AMOC. Antarctica’s contribution is primarily linked to its impact on the strength and position of atmospheric westerlies over the high latitudes of the Southern Hemisphere, which strengthens the AMOC by enhancing Ekman upwelling and Agulhas leakage in the Southern Ocean. The synergistic effect of the Tibetan Plateau and Antarctica is instrumental in forming the contemporary pattern of the AMOC. The TP2AT scenario is more effective in establishing the AMOC compared to AT2TP. In the latter scenario, a strong Pacific Meridional Overturning Circulation (PMOC) exists before the introduction of the Tibetan Plateau. The rise of the Tibetan Plateau must first terminate the PMOC before initiating the AMOC.
New approach to the tendencies of coastal dynamics of the Curonian Spit based on wave reanalysis data 
Authors: Brazdžiūnas Pranciškus , Pupienis Donatas , Jarmalavičius Darius , Žilinskas Gintautas
Published: March 2024

The Curonian Spit is 98 km long, while Lithuania has a 50 km stretch of coastline. The evolution of the Curonian Spit is linked to the alongshore northward sediment transport. However, varying tendencies of coastal dynamics have been observed between the different sections. Hydrodynamic and aeolian processes, generated by the prevailing westerly winds have been identified as the main factors controlling the coastal dynamics. The reasons for inconsistent coastal trends along different sections in a relatively short coast stretch (50 km) remain unclear, despite similar coastal morphology and similar prevailing hydrometeorological conditions.The previous studies on Curonian Spit coastal development were based on wind, sea level and visual wave observation data collected only in two hydrometeorological (Klaipėda and Nida) stations. The limited spatial distribution of this data allowed only assumptions to be made about the influence of wave regime on the coastal dynamics of the Curonian Spit in different stretches.The aim of this study was to analyse the spatial variability of the changes in wave regime along the Curonian Spit sea coast and investigate their relationship with the changes in sediment volume. The main goal of this study is to identify the impact of wave regime on the variance of coastal development along the Curonian spit.The spatial variance of sediment volume was calculated from the 12 cross-shore levelling profiles from the 2003-2019 period. Wave parameters were analysed using Baltic Sea long-term wave reanalysis data, generated with WAM spectral wave model by the Finish Meteorological Institute (FMI). The yearly changes in mean wave parameter values were compared to the sediment volume at the corresponding measurement points using Pearson correlation and regression analysis.Sediment accumulation in varying magnitude were observed along the entire Lithuanian coast of the Curonian Spit during the study period. The homogeneous changes of wave parameters were established along the entire spit, meaning that the highest and the lowest waves usually occur at the same sites. Significant negative correlation (r= -0.5‒ -0.7; p
Contribution of programming language to novel mine risk assessment project
Authors: Mabe Fogang Pieride , Huo Bingjie
Published: March 2024

When excavating a tunnel, the stresses are distributed asymmetrically along the tunnel cross-section. Other factors, particularly slope friction force and excavation speed, can also contribute to the deformation and displacement of a tunnel. Despite this, several authors have used the complex potential method to predict the ground deformation surrounding the tunnel. However, their applicability to the ground response caused by the asymmetric stress distribution around the mine wall is analyzed in this context. This project, therefore, proposes an approximate solution on the slope to predict the mine cross-section deformation. The solution is based on the complex potential method to predict analytically and numerically the ground deformation around the tunnel. However, two variables called the “complex potential functions” for the Laurent series expansion are used for the stress redistribution to the tunnel boundary conditions. Data from the Datong mine case are used to justify the proposed analytical solutions. The solution is an essential guide for analyzing deformations in complex geological conditions and structures, such as steeper slopes.
Atmospheric deposition and its impacts in China over the last four decades and beyond
Authors: Yu Qian
Published: March 2024

In addition to causing atmospheric pollution, anthropogenic emissions also have impacts on ecosystems through atmospheric deposition, e.g., acidification and eutrophication owing to acid deposition (i.e., sulfur and nitrogen deposition). China currently has the globally highest acid deposition, yet research on its status, impacts, causes, and controls is lacking. Here, we compiled data and calculated critical loads regarding acid deposition. The results showed that the abatement measures in China have achieved a sharp decline in the emissions of acidifying pollutants and a continuous recovery of precipitation pH, despite the drastic growth of the economy and energy consumption. However, the risk of ecological acidification and eutrophication showed no significant decrease. With similar emission reductions, the decline in areas at risk of acidification in China (7.0%) lags behind Europe (20%) or the USA (15%). This was because, unlike Europe and the USA, China's abatement strategies primarily target air quality improvement rather than mitigating ecological impacts. Given that the area with the risk of eutrophication induced by nitrogen deposition remained at 13% of the country even under the scenario of achieving the dual targets of air quality and carbon dioxide mitigation in 2035, we explored an enhanced ammonia abatement pathway. With a further 27% reduction in ammonia by 2035, China could largely eliminate the impacts of acid deposition. This research serves as a valuable reference for China's future acid deposition control and for other nations facing similar challenge.
Testing multiple ambient noise methodologies to map the basement of small-scale sedimentary basins
Authors: Diaz Jordi , Ventosa Sergi , Schimmel Martin , Ruiz Mario , Macau Albert , Gabàs Anna , Martí David , Akin Özgenç , Verges Jaume
Published: March 2024

The potential of different ambient noise methodologies to map the geometry of a small-scale sedimentary basin has been tested using data acquired in the Cerdanya Basin (eastern Pyrenees). We present results based on a 1-year long broad-band deployment covering a large part of the Eastern Pyrenees and a 2-month long high-density deployment covering the basin with interstation distances around 1.5 km. The explored techniques include autocorrelations, ambient noise Rayleigh wave tomography, horizontal-to-vertical spectral ratio, and band-pass filtered ambient noise amplitude mapping. The basement depth estimations retrieved from each of these approaches, based on independent datasets and different implicit assumptions, are consistent, showing that the deeper part of the basin is located in its central part, reaching depths of 600-700 m close to the Têt Fault trace bounding the Cerdanya Basin to the NE. The results show also that when high-density seismic data are available, HVSR and ambient noise amplitude analysis in a selected frequency band are useful tools to quickly map the basement of a sedimentary basin. On the other hand, surface wave tomography, more complex to obtain, provides detailed information on the 3D velocity structure. Besides this methodological aspect, our results help to improve the geological characterization of the Cerdanya Basin and will provide further constraints to refine the seismic risk maps of an area of relevant tourism and economic activity.
Global and Regional Hydrological Impacts of Global-Scale Forest Expansion
Authors: King James A. , Weber James , Lawrence Peter , Roe Stephanie , Swann Abigail , Val Martin Maria
Published: March 2024

Global-scale afforestation, reforestation, and forest restoration have gained significant attention as climate change mitigation strategies due to their significant carbon dioxide removal (CDR) potential. However, there has been limited research into the unintended consequences of increasing global forest cover from a biophysical perspective. Using the Community Earth System Model version 2 (CESM2), we apply a plausible global forestation scenario, which aligns with current net zero proposals and commitments, within a Paris Agreement-compatible warming scenario to investigate the land surface and hydroclimate response. Compared to a control scenario where land use is fixed to present-day levels, the forestation scenario is significantly cooler at low latitudes (0.8°C-3.0°C) by 2100, driven by a 10% increase in evaporative cooling in forested areas. However, shifts from grassland or shrubland to forest (afforestation) lead to a doubling of plant water demand in some regions, causing significant decreases in soil moisture (5% globally) and water availability (10% globally) in regions with increased forest cover. While there are some increases in low cloud and seasonal precipitation over these regions, with lower and in some places negative cloud radiative forcing, the impacts on large-scale precipitation and atmospheric circulation are limited. This contrasts with the response of precipitation to simulated large-scale deforestation reported in previous modelling studies, which significantly decreased low-latitude rainfall. The forestation scenario demonstrates local cooling benefits in low latitudes without major disruption to global hydrodynamics beyond those already projected to result from climate change, in addition to the cooling associated with CDR. However, the water demands of extensive afforestation of non-forest biomes have implications for its viability given uncertainty in future precipitation changes, especially in the tropics.
A new deep sea reference record for the Paleocene-Eocene Thermal Maximum: IODP Expedition 392 Site U1580 (Agulhas Plateau, Southwest Indian Ocean)
Authors: Westerhold Thomas , Bohaty Steve , Penman Donald , Burkett Ashely , Dallanave Edoardo ,   Expedition 392 Scientists
Published: March 2024

The abrupt onset of the Paleocene-Eocene Thermal Maximum (PETM) 56 million years ago represents one of the largest transient greenhouse gas-driven global warming event in the last 100 million years. Caused by a geologically rapid injection of exogenic carbon into the ocean and atmosphere system, the PETM is associated with large-scale ocean acidification. Related widespread dissolution of marine pelagic carbonate deposits, particularly in the early stages of the event, complicates marine paleoclimatic reconstructions and the establishment of robust age models at many sites. Recently, a new deep-sea sediment record spanning the PETM was recovered from the southern Agulhas Plateau in the Southwest Indian Ocean during International Ocean Discovery Program Expedition 392. The uppermost Paleocene/lowermost Eocene interval at Site U1580 was drilled in two parallel holes at 2560 m water depth, and consists of 75‒95% carbonate across the event, with a reduction to 75‒65% at the PETM onset. X-ray fluorescence-derived core scanning elemental data at 5mm and 10mm resolution and an unprecedented high-resolution bulk carbonate stable carbon and oxygen isotope record define a new marine composite reference record for the PETM at this site. The record is comparable to Ocean Drilling Program Site 690 (2914 m water depth) in the Atlantic sector of the Southern Ocean, where the event was first described and is still a primary reference sequence for paleoclimate reconstructions. Unlike Site 690, however, Site U1580 elemental data shows a clear cyclicity throughout the event that can be utilized for cyclostratigraphy. Additionally, the highly resolved bulk carbonate stable carbon isotope record provides a new reference for global correlation, which establishes a new benchmark for the different phases of the PETM. Here we present this new record and discuss the implications for timing and duration of the event, and set the stage for multi-proxy paleoclimate reconstructions spanning the PETM at IODP Site U1580.
Nutrient balance as a tool in multi-objective forest management aiming at climate change mitigation and other ecosystem services
Authors: Palviainen Marjo , Laurén Annamari
Published: March 2024

Forests are expected to provide several ecosystem services, such as wood production, clean water and carbon sequestration and storage, simultaneously. The basic aerial unit of forest management is gradually changing from stand to catchment scale. Catchment scale management of forest nutrient balance is an important part of modern forestry. A leap towards holistic management of ecosystem services through customised forest management strategies has become possible when high resolution forest, terrain, and soil data can be combined with detailed process-based ecosystem models. We have developed catchment level, spatially distributed nutrient balance and hydrology models, which calculate location-specific forest growth, carbon and nutrient dynamics, and the nutrient export to water courses. Model applications have shown that the nutrient export is very unevenly distributed throughout catchments: 5 % of the catchment area can produce 25% of the nitrogen export. This identification of nutrient export hotspots facilitates knowledge-based planning of forest operations and cost-efficient locating of water protection. We have found that catchments may also contain locations where the stand growth is nutrient limited. This opens the possibility for precision fertilization in which the quality, dose and timing of the fertilization can be adjusted so that the site-specific nutrient supply meets the nutrient demand. Our simulations indicate that especially in peatland forests, fertilization together with water and forest management can effectively improve wood production, decrease carbon emissions and control nutrient export to watercourses.  Furthermore, these models can be used to compare different harvesting methods and forest management strategies with respect to multiple ecosystem services. Process-based ecosystem models including nutrient balance and geospatial high-resolution data are particularly useful in forecasting the effects of climate change allowing development of pro-active adaptation schemes in a specific catchment.
Decreasing carbon emissions in boreal peatland forests using fertilization and less intensive drainage in current and changing climate
Authors: Laurén Annamari , Palviainen Marjo
Published: March 2024

Different climate scenarios predict a clear rise in temperatures and a modest increase in precipitation to high latitudes. In forested peatlands, the consequent lowering of the water table and increasing peat temperature will enhance organic matter decomposition leading to higher nutrient release and CO2 emissions from the peat. These biogechemical changes will fundamentally alter the management schemes of peatland forests. Hydrological and biogeochemical processes in forested peatlands are complicated, interlinked and characterized by different feedback mechanisms. In addition, all these are dependent on weather conditions, peat characteristics, drainage dimensions, and stand structure.  High-resolution geospatial data combined with process-based ecosystem models provides a solution in searching for new forest management schemes that balance between different ecosystem services. We have developed this kind of ecosystem model, peatland simulator SUSI, and applied it to study how manipulation of drain network, ash fertilization and forest management affect tree growth, greenhouse gas balance and nutrient export to water courses under different temperature and rainfall scenarios. We found that without a change in the water management, the stand growth, the soil C emissions and nitrogen export to water courses will increase substantially. However, less intensive drainage together with ash fertilization helped to mitigate the harmful effects of changing climate whilst keeping the stand growth in adequate level. 
Mineralogy and P-T conditions of Superior- type Iron Formation fromBundelkhand Craton, North Central India
Authors: Bisht Bhanu Pratap Singh
Published: March 2024

Iron Formations (IF) are economically significant sedimentary rocks primarily formed in the Precambrian evolutionary history of the Earth. In the Precambrian period, Iron Formations were deposited within marine sediments on stable continental margins (superior-type) and in association with volcanic rocks and many volcanic Massive Sulphide (VMS) deposits (Algoma-type). Most scientists agree that for BIF to form, photosynthesis and changing ferrous iron from seawater into mixed-valence iron (oxy-hydroxide) oxides and carbonate phases during oxidation are needed.The present study is based on the Superior-type BIFs from the Girar Supracrustal Belt of Southern Bundelkhand terrane, which mainly consists of Neoarchean K-rich granitoids with a minor volume of a schist complex, TTG, sanukitoids, and mafic-ultramafic layered intrusion. The Girar schist (metasedimentary) belt is mostly made up of two types of rocks: (i) quartzite and (ii) BIFs. There are also some dolomitic marble and chlorite schist lenses close to the quartzite/BIF boundary. The BIFs consist of thick-bedded quartz and hematite with magnetite. The quartzites display low-grade metamorphism of fuchsite- and hematite-bearing quartz arenite with thick meta-argillite (schist) laminae and lesser quartz pebble conglomerates.P-T pseudosection modelling indicates that Fe-carbonates and iron-oxyhydroxides (minnesotaite) are the primary phases that stabilize at 200 – 250 O C, 0.1–0.15 GPa. Subsequently, the low-temperature phases experienced dehydration and decarbonisation reactions with an increase in temperature, leading to the stabilisation of hematite and magnetite. The absence of orthopyroxene in the BIFs suggests these rocks suffer amphibolite faciesmetamorphism, which is uncommon in generally undeformed superior-type BIFs.
The combined  impact of Indian Ocean dipole and ENSO on the North Atlantic-European circulation during early boreal winter in re-analysis and in the ECMWF-SEAS5 hindcast 
Authors: Kucharski Fred , Raganato Alessandro , Abid Muhammad Adnan
Published: March 2024

This study investigates the delayed influence of the Indian Ocean dipole (IOD),  isolated and combined with ENSO, on the early winter North Atlantic-European (NAE) circulation.  Results reveal that a positive IOD induces a strong response in the NAE region during December, leading to a positive North Atlantic Oscillation (NAO)-like pattern. This circulation response also induces a north-south precipitation dipole and a positive temperature anomaly over Europe. The underlying physical mechanism involves a rainfall dipole response to the IOD in the Indian Ocean, persisting into early winter, which triggers a perturbation in the zonal wind within the subtropical South Asian jet (SAJET) region. This initiates a wave-train that propagates northeastward into the North Atlantic. Additionally, a positive IOD enhances transient eddy activity in the European region. Transient eddy forcing provides strong positive feedback to the NAO-like anomaly. While the ECMWF-SEAS5 seasonal hindcast system reproduces the sign of the response, its magnitude is considerably weaker. The possible reasons for this weak response are investigated. The model can reproduce the delayed rainfall dipole response to the IOD, however, the structure of the response shows some differences with the re-analysis. The zonal wind perturbation in ECMWF-SEAS5 in the SAJET region is only about half of the re-analysis magnitude. Moreover, the wave propagation into the stratosphere, as estimated by the 100h𝑃𝑎 eddy heat fluxes, plays a minor role in the re-analysis and the model.
Variability of calving and ice flow during a two-week period using terrestrial radar interferometry
Authors: Dachauer Armin , Kneib-Walter Andrea , Vieli Andreas
Published: March 2024

Frontal ablation at tidewater outlet glaciers is responsible for a major part of mass loss of the Greenland Ice Sheet. This underscores the need to understand the underlying processes, such as calving and ice flow, with regard to global sea level rise. In this study we explore the temporal and spatial variability of calving activity and ice flow at the major tidewater outlet glacier Eqalorutsit Kangilliit Sermiat (also referred to as Qajuuttap Sermia) in South Greenland and thereby try to get insights into the forcing and relationships between these two processes. This requires high-resolution data which we achieve by using a terrestrial radar interferometer. The instrument provides a temporal resolution of 1 minute and a spatial resolution of a few meters and was running continuously for a two-week field period in August 2023. The data shows considerable spatial and temporal variability of both calving activity and ice flow. Parts of the flow variability can be attributed to a diurnal cycle that is forced by surface melt, whereas enhanced calving activity seems to be tightly linked to locations of major subglacial discharge plumes.
Ionospheric irregularity reconstruction using multisource data fusion via deep learning
Authors: Tian Penghao
Published: March 2024

Ionospheric sporadic E layers (Es) are intense plasma irregularities between 80 and 130 km in altitude and are generally unpredictable. Reconstructing the morphology of sporadic E layers is not only essential for understanding the nature of ionospheric irregularities and many other atmospheric coupling systems, but is also useful for solving a broad range of demands for reliable radio communication of many sectors reliant on ionosphere-dependent decision-making. Despite the efforts of many empirical and theoretical models, a predictive algorithm with both high accuracy and high efficiency is still lacking. Here we introduce a new approach for Sporadic E Layer Forecast using Artificial Neural Networks (SELF-ANN). The prediction engine is trained by fusing observational data from multiple sources, including a high-resolution ERA5 reanalysis dataset, Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) radio occultation (RO) measurements, and integrated data from OMNIWeb. The results show that the model can effectively reconstruct the morphology of the ionospheric E layer with intraseasonal variability by learning complex patterns. The model obtains good performance and generalization capability by applying multiple evaluation criteria. The random forest algorithm used for preliminary processing shows that local time, altitude, longitude, and latitude are significantly essential for forecasting the E-layer region. Extensive evaluations based on ground-based observations demonstrate the superior utility of the model in dealing with unknown information. The presented framework will help us better understand the nature of the ionospheric irregularities, which is a fundamental challenge in upper-atmospheric and ionospheric physics. Moreover, the proposed SELF-ANN can make a significant contribution to the development of the prediction of ionospheric irregularities in the E layer, particularly when the formation mechanisms and evolution processes of the Es layer are not well understood.
A systematic bias in future heatwave diagnostics throughout the seasonal cycle
Authors: Meindl Maximilian , Brunner Lukas , Voigt Aiko
Published: March 2024

Human-induced climate change is leading to a warming Earth, resulting in more frequent and intense temperature extremes. Daily temperature extremes can be defined following various approaches, with relative percentile-based thresholds being a common method. Here we explore spatio-temporal heatwaves across the seasonal cycle derived from daily temperature extremes, emphasizing the critical role of the extreme threshold chosen in their definition.To investigate the sensitivity of heatwave characteristics to the extreme threshold definition, we focus on the approach utilizing a so-called moving threshold. This method involves a 31-day running window to increase the sample size for percentile calculations as well as an additional 31-year running window to account for the impact of global warming. We recognize that introducing a seasonal running window may introduce biases in threshold exceedances. To address this issue, Brunner and Voigt (2023) proposed a simple bias correction method, involving the removal of the mean seasonal cycle before percentile threshold calculation, which we also use here to explore effects on downstream impact metrics. We focus on the 99th percentile as threshold and show the potential for a significant bias in the extreme frequency, exceeding 50% in certain regions according to 5 selected CMIP6 models. Our findings further reveal that without bias correction this also leads to a substantial underestimation of derived heatwave properties, in particular area, duration, and magnitude. For the ACCESS-CM2 model, the difference in heatwave area can reach up to 40%, when comparing bias-corrected and not bias-corrected results for the 100 biggest events in the period 1960-1990.Our results contribute to a better understanding of the implications of using a seasonally running window on heatwave characteristics, providing valuable insights for future climate projections. We emphasize the importance of adopting appropriate methods and bias correction techniques to enhance the accuracy of temperature extreme assessments in the context of ongoing climate change. References:Brunner and Voigt (2023): Revealing a systematic bias in percentile-based temperature extremes. EGU General Assembly 2024. EGU24-1722
Power law error growth in a more realistic atmospheric Lorenz system with three spatiotemporal scales
Authors: Bednar Hynek , Kantz Holger
Published: March 2024

Inspired by the Lorenz (2005) system, we mimic an atmospheric variable in one dimension, which can be decomposed into three spatiotemporal scales. This is motivated by and consistent with scale phenomena in the atmosphere. When studying the initial error growth in this system, it turns out that small scale phenomena, which contribute little to the forecast product, significantly affect the ability to predict this product. In other words, a more precise knowledge of the initial condition does not translate into a longer closeness of the forecast to the truth. Lorenz gave a sketch of such error growth. After a fast growth of the small scale errors with saturation at these very same small scales, the large scale errors continue to grow at a slower rate until even these saturate. We will present that scale dependent error growth can be translated into power law error growth. We will explain how parameter values of the power law are related to the error growth properties of the individual scales. We apply the results to the initial error growth of numerical weather prediction systems and show that the validity of the power law would imply a finite prediction horizon.
Impacts of the Tibetan Plateau on aridity change over the Northern Hemisphere
Authors: Gao Zhaokui , Guan Xiaodan , He Bian , Zhao Long , Xie Yongkun , He Yongli , Ji Fei
Published: March 2024

Aridity change in the Northern Hemisphere (NH) is a vital topic in exploring climate change. The Tibetan Plateau (TP) is essential for its role in climate variability over the NH. We applied the ensemble empirical mode decomposition (EEMD) to the aridity index (AI) from 20°-60°N in this study. The EEMD method extracts a set of intrinsic mode functions (IMFs) with various timescales. Results from our analysis reveal that the multi-decadal oscillation of AI makes 35% contribution to the variability of the AI. And the multi-decadal oscillation of the TP thermal forcing makes 18.15% contribution to the multi-decadal variability of the AI, which is often ignored in previous studies. The dynamic and thermal effects of the TP also affect the AI change, which illustrates a mode of meridional difference around 40°N, with wetting in the north and drying in the south. Meanwhile, the dynamic effects of the TP lead to latitudinal difference north of 40°N in Asia, with drying Northeast Asia. Such meridional and latitudinal differences over South Asia, Southeast Asia and southern China are controlled by a high-pressure system from 850 hPa up to 500 hPa, which results in an increase of sinking motion from 20°-40°N with obvious continuous drying effect.
Heat impacts during days and nights under climate overshoot: a single hazard multi-impact approach
Authors: Kropf Chahan M. , Leung Kam Lam , Mc Caughey Jamie W.
Published: March 2024

Heat stress is a significant threat to human health and well-being, particularly in urban areas, and is expected to worsen in the future due to climate change. This study investigates the impacts of heat stress on human health in Lisbon, Portugal, during both days and nights under climate overshoot scenarios. The study employs a single hazard multi-impact approach to assess the health impacts of heat stress, considering both acute and long-term effects. The results show that the impacts of heat stress on human health are unequally distributed across the population, with some parishes being more affected than others. The study also finds that the impacts of heat stress will increase dramatically under current climate policies. In the daytime, heat stress is primarily driven by heat waves and maximum temperatures, leading to acute effects on human health, such as mortality. These effects are most pronounced in certain parishes and are expected to increase significantly even by 2040. Behavioural adaptation strategies such as adapting working hours have some potential to reduce heat impacts in certain settings. At night, heat stress is primarily driven by minimum daily temperatures, leading to sleep loss and long-term effects on health. Adaptation options for mitigating these impacts might require infrastructure investments. These findings highlight the need for targeted adaptation strategies to address the unequal distribution of heat stress impacts even under climate overshoot.
Influences of moisture transport on changes in extreme precipitation in Central Plains Urban Agglomeration, China 
Authors: Chen Yufan , Zhang Shuyu , Chen Deliang , Liu Junguo
Published: March 2024

In recent decades, the Central Plains Urban Agglomeration of China (CPUA) has faced recurring extreme precipitation events (EPEs), causing severe flood disasters, endangering residents, and inducing significant property losses. This study examines the spatiotemporal patterns of summer EPEs in the CPUA from 1961 to 2022. The Hybrid Single-Particle Lagrangian Integrated Trajectory model was used to trace the water vapor trajectories associated with these events and the atmospheric circulations linked to diverse moisture transports were identified. The findings reveal an overall increase in both the intensity and frequency of summer EPEs, particularly intensifying over urban areas while displaying more frequent yet weaker precipitation in mountainous regions. Moisture contributing to these events originates from sources including Eurasia, the northern and southern Western North Pacific, as well as the Bay of Bengal and South China Sea. Notably, contributions from Eurasia and the Northern Western North Pacific have increased, whereas those from the Bay of Bengal and the South China Sea have decreased. Events fueled by Western North Pacific moisture show intensified impacts on urban areas, driven by anomalous anticyclonic patterns and the formation of the Huang-Huai cyclone, inducing vigorous convective activity over the CPUA. The proliferation of the Western North Pacific Subtropical High facilitates warm air transport, converging with colder air from inland areas, resulting in extreme precipitation.
Is it more conservative to use the crab steering during sugar beet harvesting? A case study from Lower Saxony, Germany
Authors: Augustin Katja , Lorenz Marco , Duttmann Rainer , Kuhwald Michael
Published: March 2024

Sugar beet is one of the crops grown in Germany with the highest intensity of traffic on the field. Not only are there very high numbers of passes by the machines during the season, but the sugar beet harvesting vehicles are also among the largest and heaviest machines in use in Germany. The heavy harvesters are also used elsewhere in the world. In order to avoid multiple passes with the heavy wheel loads, the machines can often offset their rear axles parallel to the direction of travel - the so-called crab steering (CS). This distributes the load over a larger area, but also means that more area is covered in the field.This study examines whether the distribution of wheel loads over a larger area using CS shows a significant difference in soil settlement and deformation compared to traffic without the use of crab steering (wCS). Different moisture contents of the soil are taken into account.The model named FiTraM was used to model the traffic. The calculation of the soil deformation is based on empirical formulas, which are specially adapted to this field and the harvester.The subsoil in particular is considered, as soil deformation should be avoided there, since it is difficult and cost-intensive to repair.The results show that there are no significant differences in the distribution of soil deformation between CS and wCS.  In general, the moisture content of the soil determines the extent of deformation. In moist to very wet conditions (approx. 35 - 37 Vol-%), the first pass already achieves such a high degree of soil deformation that it should be avoided in practice. When the soil is dry (approx. 25-30% by volume), no soil deformation occurs in the subsoil in any of the variants - only slight deformation occurs in the topsoil. There are likewise no significant differences between the two traffic variants between 31 and 34 Vol.-% soil moisture.In summary, it can be assumed that a wheel or axle of the beet harvester is already so heavy that it makes little difference whether the machine is running in CS or not. The limiting factors are the total weight and the soil moisture content during traffic.