bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphodynamics of the world’s large tropical rivers drive a carbon pumping mechanism  
Authors: Salerno Luca , Camporeale Carlo
Published: March 2024

This study investigates the eco-morphodynamic activity of major tropical rivers in the Tropics, aiming to quantify the carbon flux originating from riparian vegetation into inland waters. Employing a comprehensive multi-temporal analysis of satellite data, developed on the Google Earth Engine cloud computing platform, spanning from 2000 to 2019, at a spatial resolution of 30 meters, we focused on all tropical rivers with a width exceeding 200 meters. Our research reveals the existence of a highly efficient Carbon Pump mechanism, where river morphodynamics play a pivotal role in driving carbon export from the riparian zone. This, in turn, stimulates net primary production through a synergistic process involving floodplain rejuvenation and colonization.The quantification of this unique pumping mechanism underscores its substantial contribution, alone accounting for an annual mobilization of 12 ± 0.96 million tons of carbon in these tropical rivers. We identified distinct signatures of fluvial eco-morphological activity that serve as proxies for assessing the carbon mobilization capability linked to river dynamics. The study also delves into the interplay between river migration and carbon mobilization, shedding light on the potential impacts on the carbon intensity of planned hydroelectric dams in the Neotropics.We highlight the significance of the river-carbon nexus, emphasizing the necessity for a comprehensive approach in formulating effective water policies that consider the intricate relationships among river dynamics, carbon flux, and environmental phenomena. 
Trends in snow persistence at the Central Pyrenees derived from 40 years of Landsat satellite images
Authors: Navarro Planes Martí , Cea López Cristina , Pons Xavier , Pesquer Mayos Lluís , Gómez Gener Lluís
Published: March 2024

An accurate quantification of the spatiotemporal dynamics of seasonal snow is essential for understanding and predicting the impacts of climate change on mountain regions and their feedback on global climate. This is especially critical in southernmost Mediterranean mountains such as the Pyrenees, where the extent of seasonally snow-covered zones (or persistent snow areas) are expected to decrease more abruptly than other mountain regions of the world. Here we use 40 years of Landsat satellite images (from 1984 to 2023) to study the trend in snow surface area and snow persistence (the fraction of time that the snow remains on the ground) across different spatial scales (from catchment to region) within the Central Pyrenees, Spain. In addition, snow surface data has been correlated with altitude and incident solar radiation to understand the role of topography on driving snow persistence distribution patterns.
Unraveling Heterogeneous Fluid Pathways in Basaltic Lava Flow Facies: Implications for subsurface CO2 Storage
Authors: Auzemery Antoine , Bailly Cédric , Carlos Pallares , Nader Fadi , Schmitz Julien
Published: March 2024

Unlocking the Potential of Subsurface Geological Formations for Sustainable Energy and CO2 Storage necessitates a nuanced understanding of fluid dynamics, notably within diverse volcanic facies. Addressing pivotal challenges entails delving deeper into reactive flow physics and minimizing uncertainties in geological assumptions, particularly pertaining to top seals and vertical reservoir barriers. This study examines the complexities of fluid flow within reactive volcanic porous media, specifically focusing on fractured lava sequences, presenting a promising avenue for future energy storage strategies. Stemming from a comprehensive field study in the Faroe Islands, our research seeks to unravel the reservoir architecture and fluid pathways within fractured lava sequences, with a specific emphasis on two distinct basaltic lava flow facies: the Compound and Tabular lava flows.Leveraging techniques such as drone-based photogrammetry, geological surveys, geochemical and petrophysical data, we seek to construct 3D synthetic reservoir models of these contrasting volcanic facies. The Compound facies at Vidoy showcases lobe-like structures formed from ancient fluid lava tunnels, favoring subsequent fracturing in an alveolar network. In contrast, the Tabular facies at Suduroy, characterized by massive (10m thick) layers, exhibits contrasting microlithic cores with limited porosity and highly porous tops, featuring corded facies networks. This diverse cooling structure engenders partitioned permeability pathways, with predominantly vertical fracturing across the lava flow and horizontal networks at its porous tops.These findings yield crucial insights into the heterogeneous nature of fluid pathways within distinct volcanic facies, establishing the groundwork for refining models crucial for sustainable energy storage strategies. Addressing challenges tied to limited subsurface data and geophysical resolution underscores the need for refined methodologies in evaluating volcanic reservoir properties. This research significantly contributes to upscaling properties in basaltic porous formations, deepening our understanding of their potential as reservoirs or seals for sustainable energy storage solutions.
Towards operational mapping and estimation of snow cover phenology parameters in the Atlas Mountains, Morocco, using multi-sensor satellite data and Google Earth Engine. 
Authors: El jabiri youssra , Boudhar Abdelghani , Htitiou Abdelaziz , Sproles Eric , Bousbaa Mostafa , Bouamri Hafsa , Chehbouni Abdelghani
Published: March 2024

The lack of knowledge about the temporal variability, or snow cover phenology and its spatial variation poses enormous challenges to water resource managers who mostly rely on a few weather stations with limited spatial coverage which prevents them from having a complete understanding of snow changes as a whole. Meanwhile, the free availability, wide-coverage, frequent updating, and long-term time horizon make data from programs such as Landsat and Sentinel-2 a valuable data source for reliable snow data information at an unprecedented spatial scale.In this context, this research aims to derive the snow phenology parameters (first day of snowfall, last day of snow melt; and snow duration) over Morocco’s Atlas Mountains by combining over 10,000 images from Landsat-8 and Sentinel-2 satellites for four hydrological years (2016-2021) to create a harmonized product with a time interval of about 3 days using Google Earth Engine platform. The time series produced allowed us to create detailed maps of snow cover and extract a homogeneous normalized difference snow index (NDSI) profile over the four years whereby we were able to determine the optimal threshold to separate the presence of snow from its absence.  The results showed that derived seasonality snow metrics provide considerable variation in both time and space, where an increase in snowpack measurement values at higher elevations can be observed. The experimental results demonstrate that the proposed workflow can accurately derive snow seasonality timing with almost a day and a half delay than the in-situ observed dates and with an overall accuracy equal to 0.96.  We expect these results to benefit various applications such as hydrological modeling, natural hazards, and regional climate change studies.
Constraining atmosphere-terrestrial-aquatic carbon cycle processes at national and ecoregional scales with radiocarbon data: Introducing the Radiocarbon Inventories of Switzerland (RICH) project
Authors: Eglinton Timothy , Graven Heather , Hagedorn Frank , Szidat Soenke , Brunmayr Alexander , Duborgel Margaux , Geissbuehler Dylan , Laemmel Thomas , Minich Luisa , Mittelbach Benedict , Rhyner Timo , White Margot
Published: March 2024

New constraints on carbon exchanges between atmospheric, terrestrial and aquatic systems are needed to reduce uncertainty in future predictions of the global carbon cycle and climate change. Radiocarbon is a powerful tool for studying the carbon cycle due to its to its ~5700-year half-life that sheds light on processes occuring on centennial to millenial timescales, as well as the 14C “bomb spike” resulting from above-ground nuclear weapons testing in the mid-20th Century that serves as a tracer of carbon flow among more rapidly cycling pools. The “Radiocarbon Inventories of Switzerland” (“RICH”) project is a collaborative initiative that involves undertaking a first-of-its-kind, national-scale 14C survey spanning all major carbon pools and encompassing the five different Swiss ecoregions. The project is acquiring a comprehensive “snapshot” of 14C measurements for carbon species in the atmosphere, soils and the hydrophere (e.g. 14C in atmospheric and soil-derived gas samples, 14C in bulk samples and different sub-fractions of soil, water and sediment samples), and developing historical context through 14C analysis of natural archives and of archived samples spanning the pre-bomb era to the present. The measurements are being used to study various carbon cycle processes, including turnover rates of different soil carbon fractions, budgets of riverine carbon, and anthropogenic emissions of CO2 and CH4. New, integrated atmospheric-terrestrial-aquatic carbon cycle models are being developed and calibrated, and existing models are being evaluated. This presentation will outline the goals and scope of the RICH project, and provide illustrations of the information that is now flowing from this collaborative undertaking. The project structure is envisioned to serve as template that can be  adapted in carbon cycle studies on regional to global scales, and the scientific outcomes will be relevant not only to Switzerland but also to the broader understanding of carbon cycle processes.
Identifying and accounting for the Coriolis effect in satellite NO2 observations and emission estimates
Authors: Potts Daniel , Timmis Roger , Ferranti Emma , Vande Hey Joshua
Published: March 2024

Recent developments in atmospheric remote sensing from satellites have made it possible to resolve daily emission plumes from industrial point sources around the globe. Wind rotation aggregation coupled with statistical fitting is commonly used to extract emission estimates from these observations. These methods are used here to investigate how the Coriolis effect influences the trajectory of Sentinel-5P observed emission plumes and assesses the impact of this influence on satellite-derived emission estimates. Of the 16 industrial sites investigated, 9 showed the expected curvature for the hemisphere that they reside in, 5 showed no or negligible curvature, and 2 showed opposing or unusual curvature. The sites that showed conflicting curvature reside in topographically diverse regions, where strong meso-γ-scale (2–20 km) turbulence dominates over larger synoptic circulation patterns. For high-curvature cases, the assumption that the wind-rotated plume aggregate is symmetrically distributed across the downwind axis breaks down, which impairs the quality of statistical fitting procedures. Using annual nitrogen oxide (NOx) emissions from Matimba power station, South Africa, as a test case, not compensating for Coriolis curvature resulted in an underestimation of NOx emissions of ∼ 9 % on average for the years 2018 to 2021. This study is the first formal observation of the Coriolis effect and its influence on satellite-derived emission estimates, and it highlights both the variability in the emission calculation methods and the need for a standardised scheme for these data to act as evidence for regulators. 
Published in ACP: https://doi.org/10.5194/acp-23-4577-2023
Data integration and simple water balance analysis of the Sopron Botanical Garden’s hydrometeorological station data
Authors: Muraközy Lili , Kalicz Péter , Kiss Márton , Gribovszki Zoltán
Published: March 2024

Analyzing the water balance of long-lived plant communities, like forests, requires centuries long monitoring of hydrometeorological processes. Long-term measurements, however, are essential for assessing the effects of climate change as well. In Sopron, meteorological records—one of the first systematic analyses in Hungary—started in 1711. From 1925.06.01 to 1974.04.24, the Botanical Garden's meteorological station at the University of Sopron was the city's official station. In 1974, the official station was relocated to Kuruc Hill Observatory. The remaining instruments in the Botanical Garden were still functional. The presentation goes over the basic data processing for hydrometeorological purposes, error analysis, the integration of the station's data, simple water balance estimation and FAI (forest aridity index) analysis.The following joint projects (143972SNN project and the TKP2021-NKTA-43 project) supported the preparation of this paper. TKP2021-NKTA-43 has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary (successor: Ministry of Culture and Innovation of Hungary) from the National Research, Development and Innovation Fund, financed under the TKP2021-NKTA funding scheme.Supported by the ÚNKP-23-2-III-SOE-176 New National Excellence Program of the Ministry for Culture and Innovation from the source of the National Research, Development and Innovation Fund.
How many species of loess mollusks were there in Serbia from MIS 24 to MIS 2?
Authors: Radaković Milica G. , Marković Slobodan B.
Published: March 2024

There were multiple attempts to investigate mollusks from loess sediment in Serbia, as this natural archive covers a great part of the northern territory of Serbia. However, these approaches did not have a large temporal coverage, as usually only the loess from the last glacial cycle was studied, rarely reaching the Middle Pleistocene. In recent years this research was extended until the MIS 24, according to the Danube loess stratigraphy (Marković et al., 2015). Here we present the latest information about snail species that lived in glacial conditions over the northern province of Serbia, Vojvodina. We enriched the list of found mollusks from earlier studies, by exploring the two oldest loess-palaeosol sections in Serbia, which when compiled into a composite profile cover almost one million years (Veliki Surduk – Stari Slankamen). Some problems exist when compiling all the findings of snail species in other loess sections in Serbia, such as the lack of stratigraphic interpretation in the early studies. This is why found shells from such locations can not be included in this list. We found that Chondrula tridens, Granaria frumentum, Helicopsis striata, Pupilla muscorum, Pupilla triplicata, Vallonia costata, Clausilia dubia, as well as Milacidae, Limacidae and Agriolimacidae were present from the earliest periods of loess accumulation in Serbia. The prevalent malacological assemblage of loess observed in Serbia during glacial periods suggests a predominance of mild climatic conditions characterized by a steppe environment. Conversely, less prevalent species indicate more rigorous environmental conditions, persisting during the coldest phases of certain glacials. Originally, the list of mollusks from Veliki Surduk – Stari Slankamen section included 41 species, but after adding the mollusks found in other profiles in Serbia, the list now has 62 species. The lowest diversity of mollusks was found in MIS 8. On the other hand, there were 55 species in the period MIS 2-4, but they are very diverse in their environmental preferences. Refinements and updates to this dataset require subsequent malacological investigations, which may yield the discovery of hitherto unrecorded species or the incorporation of newly identified taxa of the nine loess units formed during glacial conditions in Serbia.
A novel machine learning approach for estimating snow depth in the European Alps from Sentinel-1 imagery
Authors: Dunmire Devon , Lievens Hans , Brangers Isis , Boeykens Lucas , De Lannoy Gabriëlle
Published: March 2024

Despite the critical importance of understanding trends in snow depth and mass for making informed decisions about water resources and adaptation to climate change, these properties are challenging to quantify, especially in remote, mountainous areas with complex topography.  The increasing availability of frequent, high resolution synthetic aperture radar (SAR) observations from active microwave satellites has provided the opportunity to provide high-resolution estimates of mountain snow depth at large spatial and frequent temporal scales. As a result, novel approaches have been developed for SAR-based snow depth retrievals utilizing C-band microwave imagery. These SAR-based methods are not without their own set of limitations and are challenged by shallow snowpacks, high vegetation cover, and wet snow conditions. Here, we seek to overcome these existing challenges by developing a machine learning approach to estimate snow depth over the European Alps using Sentinel-1 imagery, an optical satellite-based snow cover product, and static information such as elevation, slope, aspect, topographical position index and forest cover fraction. We demonstrate that our machine learning approach can more accurately estimate snow depth than existing methods at independent in-situ test sites throughout the Alps and has especially improved performance in deep snow and wet snow conditions. Using feature importance scores, we also investigate when and where the Sentinel-1 data provides the most benefit for snow depth estimation. Our approach optimizes the use of Sentinel-1 imagery by learning when these observations are effective for retrieving snow depth, while relying on other topographical information when Sentinel-1 observations are not suitable.
Spatio-temporal evolution of permeability during quasi-static fault growth in granite
Authors: Brantut Nicolas , Aben Frans , Farsi Ado
Published: March 2024

In tight crystalline basement rocks such as granite, faults are known to be substantially more hydraulically conductive than the rock matrix. However, most of our knowledge of rock permeability in the laboratory and in the field relies on indirect inference, static measurements, or before/after datasets, and the spatio-temporal evolution of the permeability field during faulting remains unknown. Specifically, we would like to determine at which stage of the faulting process does permeability change most, and the degree of permeability heterogeneity along shear faults.We conducted a series of triaxial deformation experiments in initially intact Westerly granite, where faulting was stabilised by monitoring the acoustic emission rate. At many stages from pre- to post-failure states, we paused deformation and imposed macroscopic fluid flow to characterise the overall permeability of the material. In addition, we measured the pore pressure distribution in the sample, and estimated apparent permeability at different locations along the fault, from the intact ligaments to damaged regions. We monitored the propagation of the macroscopic shear fault by locating acoustic emissions.We find that average permeability increases dramatically (by around 3 orders of magnitude) near the peak stress, where the fault (as seen by acoustic emission locations) is not yet through-going. Post-peak evolution shows a more gradual increase in overall permeability, with local heterogeneities remaining along the fault, primarily controlled by small-scale fault geometry and the existence of undamaged regions as imaged by acoustic emission locations.We conclude that permeability change and fluid flow focussing occurs at very early stages of faulting, and do not require substantial slip. Our results highlight the key role of fault geometry in the fine-scale permeability structure of basement rocks. 
Modeling Earthquake Dynamics and Fault Poromechanics in the BedrettoLab FEAR Project: Opportunities & Challenges
Authors: Dal Zilio Luca ,   FEAR team
Published: March 2024

Understanding earthquake initiation, propagation, and arrest is critical for mitigating seismic risks, yet these processes remain among the most complex natural phenomena to decipher. The ERC-Synergy project FEAR (Fault Activation and Earthquake Ruptures), conducted within the Bedretto Underground Laboratory for Geosciences and Geoenergy (BedrettoLab), offers a pioneering approach to investigate these intricate mechanics. Here, we highlight the unique challenges and opportunities presented by the FEAR project, with a particular focus on computational earthquake physics and its potential to enhance our understanding of fluid-induced seismic events on broadband seismic arrays. Located ~1.5 kilometers beneath the Swiss Alps, BedrettoLab provides an unparalleled setting for a detailed study of earthquake mechanics. The FEAR project utilizes this exceptional environment to induce and monitor small-scale seismic events. By employing hydraulic stimulation on selected faults near the BedrettoLab tunnel, the project aims to initiate and observe earthquakes of approximately magnitude ~1.0. These refined methods provide a controlled setting to study the intricate details of earthquake processes closely, offering a chance to push the boundaries of current understanding of earthquake physics.Central to the FEAR project is the development and testing of hydro-mechanical computational methods capable of replicating various injection protocols. These methods systematically test a range of constitutive laws that govern the evolution of fault friction, integrating insights from laboratory experiments with fully inertial elastodynamic modeling of earthquake processes. This approach allows us to investigate the poroelastic response of the rock mass, examining how seismic and aseismic slip interact in space and time, and assessing the dynamic evolution of pore-fluid pressure due to processes such as shear-induced dilatancy and compaction. Furthermore, we employ 3D dynamic rupture simulations to explore conditions controlling either self-arresting or run-away rupture. These simulations provide critical insights into wave spectrum and attenuation near BedrettoLab, enabling us to predict the peak ground velocity (PGV) of anticipated magnitude ~1 earthquakes. This innovative modeling approach represents a significant opportunity to advance our understanding of fault mechanics and the influence of fluid interactions.In conclusion, the FEAR project within BedrettoLab provides a unique and controlled environment to study the mechanics of earthquakes. The challenges posed by this research are matched by the significant opportunities it offers for advancing our understanding of seismic phenomena. By focusing on innovative modeling techniques and integrating multidisciplinary data, this project aims to shed light on the complex dynamics of fault activation and rupture, ultimately contributing to more accurate seismic hazard assessments and safer geoenergy practices.
If there is a problem, we are the solution
Authors: esen seyran
Published: March 2024

 If there is a problem, we are the solutionAs a physics teacher for seven years, I have discovered that students learn best by doing and enjoying the subject when they love it. By using the project-based learning (PBL) method, I observed that when they encountered a problem, they made the best use of their knowledge and skills and produced solutions. We discussed the problem of global warming for our world, and throughout the year, we aim to find solutions together as students by researching alternative solutions to solve this problem. Every year, we exhibit our work at the school's science fair and provide the opportunity for other students to examine the work done. In this way, they learn different solutions together. That's why I chose the topic "if there is a problem, we are the solution" for the poster session.I plan to show examples of the projects my students have done, what problems or challenges they solved, how they worked and eventually developed a product or presentation, and how I guided them in my poster.
Approaching mass (im)balance when using artificial DNA tracer using DNA extraction methods
Authors: Köhler Sören , Foppen Jan Willem , Chifflard Peter , Leese Florian , Schadewell Yvonne
Published: March 2024

Artificial tracers play an important role in hydrological studies that aim to identify subsurface flow paths. Tracers can be used to investigate water transit times but also, for example, to assess if a structure is leak-proof. Recently, artificial DNA (artDNA) has been proposed as a tracer alongside traditional tracers such as salt. However, like traditional tracers, artDNA suffers from input tracer mass loss. This is even more pronounced in the case of artDNA. Different approaches were proposed to improve the recovery of tracer mass and thus reach the required limit of detection and quantification required for the analysis. Using column tests, a controlled experiment was designed to examine the recovery success of DNA extraction and the detachment from soil via a buffer. In each case water was spiked with artDNA, flushed through the column and subsequently the remaining molecules recovered using a magnetic bead extraction method. The ongoing experiments will show the enhancement of artDNA tracer recovery by using methods for DNA extraction from molecular biology. Further, to recover potential substrate-bound artDNA and possibly identify one source of the observed mass imbalance, a phosphate-containing buffer of high pH was used to detach artDNA from the substrate inside the column. The results will be cross-factored by comparing the recovery of tracer mass in the plain eluate vs. the DNA extracted from the eluate and by determining the substrate-bound artDNA in both cases. Insights from this experiment and the methodological advancement will be fundamental for the use of artDNA-based tracing in hydrological research.
Thermo-compositional model of the South African cratonic mantle obtained from seismic and gravity data
Authors: Tesauro Magdala , Kaban Mikhail , Youssof Mohammad
Published: March 2024

Xenolith data reveal lateral and vertical compositional variations of the upper mantle of the Precambrian cratons, indicating a different degree of refertilization with respect to the most depleted mantle in iron components, characterizing the oldest Archean cratons. The South African cratonic region is composed of the Kaapvaal and Zimbabwe craton, both of Archean age, having deep and fast lithospheric roots, which are likely depleted in heavy constituents. In contrast, there exist regions, such as the Limpopo belt, a terrane that was trapped between the Kaapvaal and Zimbabwe cratons during their collision (2.6–2.7 Ga), and Bushveld Complex, an area characterized by intraplate magmatism occurred 2.05 Ga, whose negative velocity anomalies in the upper mantle, indicate a more fertile composition due to metasomatism. To unravel the origin of these anomalies and link them to the tectonic history of the area, we apply an integrative technique based on a joint interpretation of the seismic tomography and gravity data, which can discern temperature and compositional variations. To this aim, we combine the global surface seismic tomography model [1] with the embedded regional model [2], derived from teleseismic tomographic inversion of the S-body wave dataset recorded by the Southern African Seismic Experiment. The combined seismic model is inverted for temperature, assuming an initial composition, representative of a refertilized upper mantle [3], using a mineral physics approach [4]. The composition and temperature of the upper mantle are iteratively changed, increasing progressively the amount of iron depletion, to fit the residual density, obtained from the joint inversion of the residual gravity and residual topography. The great advantage of using both the gravity field and residual topography lies in their different dependence on the distribution of density heterogeneities (depth and size). In a second type of inversion we included the GOCE gravity gradient [5]. The obtained results show that the most depleted lithosphere is confined at depth lower than 100 km, generating a temperature higher than ~200, with respect to that of a refertilized lithosphere. The Southeastern Terrane of the Kaapval craton are characterized by thicker and more depleted cratonic roots than the Zimbawe craton. The presence of a depleted mantle below the cratonic crust may indicate that the crust and mantle have been connected since the craton formation. These results, related to the different structures and properties of the upper mantle, improve our understanding of the evolution of the South African cratonic lithosphere.References[1] Schaeffer and Lebedev, 2013. https://doi.org/10.1093/gji/ggt095[2] Youssof et al., 2015. http://dx.doi.org/10.1016/j.epsl.2015.01.034[3] Griffin et al., 2004. doi:10.1016/j.chemgeo.2004.04.007[4] Conolly, 2005. doi:10.1016/j.epsl.2005.04.033[5] Kaban et al., 2022. doi.org/10.1007/s00024-021-02925-
Simulation of atmospheric organic aerosol with the 2D volatility basis during the SPRUCE-22 field campaign
Authors: Uruci Petro , Skyllakou Ksakousti , Matrali Angeliki , Pavlidis Damianos , Kaltsonoudis Christos , Pandis Spyros
Published: March 2024

Organic aerosol (OA) constitutes a major fraction of the sub-micrometer atmospheric particulate matter and is either emitted directly into the atmosphere as primary organic aerosol (POA) or formed by the partitioning onto pre-existent particles of low vapor pressure products of the oxidation of volatile, intermediate volatility, and semivolatile organic compounds (VOCs, IVOCs, and SVOCs respectively) as secondary organic aerosol (SOA). The oxidation of these compounds results in thousands of mostly unspecified oxygenated products making our understanding of SOA formation mechanisms incomplete. The volatility basis set (VBS) is a framework that has been designed to simplify these oxidation systems and to allow SOA simulation in chemical transport models (CTMs). The VBS describes the evolution of OA using a set of surrogate species with effective saturation concentrations that vary by 1 order of magnitude (referred to as 1D-VBS). This framework was extended by a second dimension (2D-VBS) to include the oxidation state (2D-VBS), which is important to quantify the degree of oxidation. Three main reasons led to this extension. First, the disadvantage of the 1D-VBS is that compounds with similar saturation concentrations can have different properties and reactivities. Second, the available measuring techniques have increasing capabilities, and they can provide detailed information about the composition of ambient and smog chamber OA (e.g., oxidation state). Third, CTMs often have difficulties in reproducing field observations.In this work, different parametrization schemes on the 2D-VBS framework were evaluated using measurements collected in the SPRUCE-22 field campaign in a remote forest area of the eastern Mediterranean site (Pertouli, Greece) in the summer of 2022. Field measurements suggested that most of the OA in the site was highly processed secondary anthropogenic and biogenic OA and also aged biomass burning OA.  The results of the default version of the model indicated both underprediction of the total OA level and its oxygen-to-carbon ratio (O:C). A series of hypotheses are tested involving the chemical aging of atmospheric OA to close the gap between the measurements and model predictions.  
Water Quality Assessment for River Ganga in Kanpur City, Uttar Pradesh, India using Machine Learning model
Authors: Umare Shubhangi , Thawait Ajay Kumar , Dhawane Sumit , Kumar Sachin
Published: March 2024

The river Ganga, revered as a lifeline of North India, is facing severe water quality degradation due to various man-made activities. The city of Kanpur, Uttar Pradesh, India, located on the west bank of the river Ganga, is known for its leather industrial area. The city produces approximately 450 million litres of municipal sewage and industrial effluent, most of this flowing directly into the holy river Ganga. Due to this, the Ganga River basin pollution is increasing daily, and to overcome this problem scientifically, there is a need to develop different models for water quality, which has been growing in recent years. The key focus of the study is to determine the Water Quality Index (WQI) along with developing a model to assess the changes in water quality over a decade in the Ganga River basin in Kanpur City. The dataset includes monthly measurements (2015-2023) of pH, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total coliform at seven distinct locations in Kanpur city, encompassing both upstream and downstream areas. Artificial Neural Networks (ANNs) were employed to construct a model to pretend, along with forecasting, the levels of dissolved oxygen (DO). The model has a notable level of accuracy in predicting dissolved oxygen (DO). The scatter plots comparing the actual and anticipated levels of dissolved oxygen (DO) during the training and testing periods exhibited a strong coefficient of determination (R2) with values of 0.90 and 0.92, respectively. Results show that the ANN model can predict water quality effects in advance, and thus, it helps to take protective actions to preserve the river free from pollution.
Keywords: Water Quality, River Ganga, Artificial Neural Network, Dissolved Oxygen.
Climate change impact assessment on the hydrological regime of the upper Ganga Basin
Authors: Ranjan Rajeev , Singh Praveen , Goswami Ajanta , Ojha Chandrashekhar , Jain Sanjay
Published: March 2024

The Hindu Kush region of the Himalayas is a valuable source of fresh water and is facing significant challenges due to its sensitivity to temperature and precipitation. Our study emphasizes Devprayag a snow-dominated area in the upper Ganga Basin. The study uses SPHY and CMIP6 Shared Socioeconomic Pathways (SSP2 4.5 and SSP5 8.5) data to project future changes in the hydrological variables.
Historical observations from 1985 to 2014 already indicate a notable increase in total runoff. The most significant increase is seen in rain runoff, followed by glacier melt and base flow. Interestingly, snowmelt has exhibited a decreasing trend over the last three decades. The hydrological system undergoes more intense changes, likely due to an increase in climatic variables.
By the end of the 21st century, the SSP 8.5 scenario predicts a rise in average annual temperature and precipitation. The SSP 8.5 scenario shows a more pronounced and rapid increase in total runoff, snow melt, and glacier melt compared to SSP 4.5. Our simulations suggest significant impacts on the hydrological regime and water balance of the region, particularly at Devprayag, where an increase of 63.21% in total flow is expected compared to 2015. Despite initial fluctuations, our analysis indicates a substantial increase in total runoff under SSP 8.5 by 2100, over 60% higher than the base year levels. This reflects a marked escalation in runoff rates over time, in line with the expected intensification of the hydrological cycle under this scenario.
Increasing footprints of flash drought over the Indus River Basin
Authors: Khurshid Tahira , Qiongfang Li , Rahim Akif
Published: March 2024

Flash drought with the characteristics of sudden onset and rapid intensification poses adverse effects on the agriculture and ecological health of a region. So far, no study has examined the dynamics of flash drought over the Indus River Basin, which has been experiencing rapid hydroclimatic changes from past decades. This study aims to assess the susceptibility of the Indus River Basin to the flash drought and asses its characteristics (i.e., intensity, frequency, extent) between 1970 and 2022. For this purpose, the weekly averaged soil moisture data set of the Global Land Data Assimilation System (GLDAS) was used to identify the events with respect to the different soil moisture layers (0-10cm, 10-40cm, 0-40cm, and 100cm). In this way, the role of most contributing soil layer in the development of flash drought in a particular climatic zone of this basin can be assessed. The study period was sliced into two halves to understand the relationship of flash drought with climatic changes. Based on these results, we conclude that the frequency of flash drought events has increased over the past two decades, which may be related to climatic changes in this region. The intensification rate and severity of flash drought show a positive correlation. Moreover, the spatial extent indicates the signals of flash drought events from Upper to Middle Indus basin. This study offers a baseline understanding for identifying the flash drought standards across the Indus basin.
Sea Level-Influenced Sedimentation in the Lower Brahmaputra Foreland Basin: Unraveling Dynamics and Provenance
Authors: Panda Sandeep , Srivastava Pradeep , Kumar Anil , Pulpadan Yunus Ali
Published: March 2024

The climate-tectonic-sea level relationship in an active mountain belt, like the Himalayas and its foreland, can be better understood by delving into the sedimentary stratigraphy of the alluvial tracts developed in the foreland basins. Alluvial fans, in particular, operate as a natural depository of sediments that can be utilized to assess the role of geological processes working between the source and sink. The physiography of these fans, including channel patterns, aggradation, and incision, is influenced by tectonics, sea level variations, and local factors like precipitation and slope, impacting the availability of eroded materials. This study based on geomorphic mapping, detailed sedimentological analysis, lithofacies analysis, and geochemical (Sr-Nd analysis) provenance characterization, as well as optically stimulated luminescence (OSL) ages of a relict alluvial fan, provides a dated sedimentation framework for the western Assam lowland areas. The fan surface lies ~40 m above mean sea level, is incised, and forms a regional valley terrace T1 composed of meandering channel deposits. Modern braided rivers flow on the T0 surface. The findings suggest that the alluvial fan is composed of three distinct lithofacies associations and aggraded during 27 to 3 ka. The bottom-most cross-bedded gravelly-sandy facies (Phase-1) indicate progradation of the fan during LGM, owing to the increased gradient of the Himalaya-bound rivers. Sheet flood deposits (Phase-2) in the middle facies formed during the Late Pleistocene-early Holocene with rising sea levels and increased precipitation. In the Mid-Late Holocene, the uppermost facies (Phase-3) deposited as rivers, responding to elevated sea levels, lost their gradient, leading to inland sedimentation within muddy meandering channels. Modern-day Gravel Sand transition zone lies much upstream of the transverse rivers in comparison to the gravel sand transition zone of the paleofan. This indicates that alluvial fan was prograding in response of increased gradient of the transverse Himalayan Rivers due to lowered sea level during LGM.  Our analysis found that falling sea level during the late Holocene was associated with greater precipitation and allowed the river to incise, to form gullies over the fan surface and form the valley terrace T1. The gravel units found in borehole stratigraphy of Upper Bengal Delta (located ~100 m below msl) relate to progradation of alluvial fans in response to lowered sea-level rather than an extreme flood events in axial channel of Brahmaputra as envisaged in earlier study. The provenance fingerprinting using Sr-Nd isotopic composition suggest that the deposits of phase-1 and phase-2 were equally sourced from the Higher and lesser Himalaya while the phase-3 deposit along with the sediments of the meander scroll deposit mimicked the composition of the modern-day bed-load which are dominated by Higher Himalayan sediments. 
Effects of two typical gravity wave processes on stratospheric ozone over the Tibetan Plateau based on radiosonde data
Authors: Chang Shujie , He Haotian , Zheng Xiangdong , Wan Lingfeng , Wang Jundong
Published: March 2024

This study analyzes the formation process and propagation characteristics of two typical gravity wave events that occurred over the Tibetan Plateau, based on the radiosonde data from Naqu Station on August 4, 2011 at 7:00-12:00UTC and August 13, 2011 at 8:00-12:00 UTC, as well as the global climate fifth-generation atmospheric reanalysis dataset (ERA5) provided by the European Centre for Medium-Range Weather Forecasts (ECMWF). The effects of the two gravity wave events on ozone are also analyzed. The results show that two gravity wave processes were broken in the tropopause and upper stratosphere respectively. The gravity wave event on August 4 captured the signal well at 400 hPa, showing a northwest-southeast structure and gradually tilting eastward. The signal decayed between 7:00-9:00 UTC, and the gravity wave completely broke and released energy near 150 hPa at 10:00 UTC. The ozone significantly decreased in the region of 200-50 hPa due to ozone exchange between the upper troposphere and lower stratosphere (UTLS). The results on August 13 showed that the gravity wave propagated from the middle stratosphere to the upper stratosphere, exhibiting a northeast-southwest structure and gradually tilting eastward. The signal weakened from the middle stratosphere at 8:00 UTC, and it broke and released energy near 7 hPa at 10:00 UTC. The ozone concentration increased in the region of 20-3 hPa. Both gravity wave events resulted in a decrease in ozone at the tropopause (200-150 hPa) and upper stratosphere (20-3 hPa), mainly due to the mixing of the upper and lower atmospheric layers caused by the gravity wave breaking, leading to ozone exchange.
Recent tendencies of extreme heat events in Italy: from 1991 to present days
Authors: Settanta Giulio , Fraschetti Piero , Lena Francesca , Perconti Walter , Piervitali Emanuela
Published: March 2024

Recent records about extreme events linked to high temperatures have enhanced the attention over the heat wave phenomenon. 2022 summer has seen a worrisome heat-related excess mortality in Europe and 2023 is the hottest year of record at the global scale, according to the Copernicus Climate Change Services.Heat waves are a major natural hazard for the most fragile parts of the population. In order to understand their impact, how communities can adapt, and to provide reliable scenarios over the close future, the key point lies in the quantitative addressing of all the aspects that compose heat waves. These include the monitoring of their change in frequency and intensity over time.This study is focused on the analysis of several temperature-extremes indices, including those specifically related to heat waves. Each of them regards a specific aspect, such as number, frequency, duration and severity. The dataset is based upon a set of quality-controlled and homogenized daily maximum and minimum temperature data from more than 250 ground-based weather stations in Italy. To catch the tendencies of the recent Italian climate, the period analysed covers the latest 33 year time span: 1991 – 2023. Data have been extracted for the most part from SCIA, the Italian national system for climate data collection, processing, and dissemination (www.scia.isprambiente.it) and have therefore undergone a series of automatic procedures which ensure the data quality.Two analyses have been used in this study: the first one is based on single stations time series and reports an extrapolated trend of the indices over the Italian territory; the second analysis is targeted to look for a global signal about temperature extremes behaviour and therefore considers stations’ data in an aggregated form. The latter analysis splits the 33 year time frame into three decades plus the last 3 years, to get a statistically robust assessment of climate tendencies over time.The two analyses are found in agreement in depicting a heat wave presence in Italy which is increasing. In particular, half of the stations report an increase of 4 days or more of heat waves per decade, with a national average value of almost 2.5 days per decade. Such behaviour is observed in terms of persistency and intensity too, composing an alarming picture for both the close and the far future. The quantitative findings of the present work can support the development of adaptation measures in the country.This work is supported by the Italian PNC - Investimento E.1- SALUTE AMBIENTE - BIODIVERSITA' - CLIMA, Missione 6 - Linea di Investimento 1.4, progetto: "Cobenefici di salute ed equità a supporto dei piani di risposta ai cambiamenti climatici". Area A-6. Codice PREV-A-2022-12376994 - Financed by the European Union - NextGenerationEU
The recent European droughts within the nudged storyline context
Authors: Rakovec Oldrich , Sanchez Benitez Antonio , Gößling Helge , Samaniego Luis
Published: March 2024

Europe has experienced a series of hot and dry weather conditions with significant socioeconomic and environmental consequences over the past decade. Here, using a novel storyline approach, we examine the extremity of the recent European droughts, and we aim to isolate the thermodynamical component of climate change from changes in atmospheric patterns, which remain controversial in climate model simulations. Our climate analysis is currently based on an ensemble (n=5) of three storyline scenarios (pre-industrial, PI; PD, present-day; 4K warming) using a CMIP6 model (AWI-CM1) with the free-troposphere winds, including the jet stream, constrained toward ERA5 data. The meteorological variables at the land surface are further used as input to a hydrological impact modelling framework using the mesoscale Hydrologic Model (mHM). Regarding the 2022 drought analysis, first, using our experiments, we quantify the extremity of the present-day (PD) European drought against pre-industrial (PI) simulations. The potential evapotranspiration shows an apparent increase across the entire ensemble between the PD and PI periods in all of Europe. The same increase holds for actual evapotranspiration in northern Europe and most of central Europe, while the Mediterranean shows a relative decrease of 15%; however, there is no clear separation between PD and PI ensembles. The river runoff exhibits significant reductions of 35-50% in the Mediterranean regions, while changes between -15% and 15% occur over the rest of Europe (with less agreement on the signal). Second, we compare how the present 2022 droughts will be further amplified under different warming-level climate scenarios. Our results suggest that the 2022 river runoff drought would be much more strongly pronounced for the 4K world concerning the PD period, by up to 50% in the Mediterranean. A clear decline, although of slightly less extremity (-15% up to -40%), would also be projected across the majority of Central Europe. These changes align with observed trends associated with anthropogenic climate change. Our ongoing efforts aim to quantify possible stress on water resources and ecosystems, by providing insights into the potential future hydrological impact of different global warming levels. The aforementioned results will be further extended to address the multi-year drought perspective during the 2018-2022 periods. This work was supported by funding from the Federal Ministry of Education and Research (BMBF) and the Helmholtz Research Field Earth & Environment for the Innovation Pool Project SCENIC.