bluuebunny/crossref_metadata_2025 huggingface dataset:
Theory and fluid simulations of ion and electron acoustic instabilities in Parker Solar Probe observations close to the Sun.
Authors: Afify Mahmoud Saad , Dreher Jürgen , Innocenti Maria Elena
Published: March 2024

Multiple electron and ion beams have been observed by the Parker Solar Probe (PSP) in the low solar atmosphere (Sun et al. 2021; Liu et al. 2023). In the presence of two resonant counter-steaming ion and electron populations, we expect the development of ion and electron acoustic instabilities, respectively (Mozer et al. 2020; Chen et al. 2020; Verscharen et al. 2022). Ion acoustic waves have indeed been observed by PSP (Mozer et al. 2021 a,b, 2023a) with characteristics that differ from previous observations. The latter is a coupled pair of high and low frequencies. Moreover, they have an electrostatic nature and a long duration of several hours. Their importance comes from the absence of whistler waves very close to the Sun, which seem to play a major role in heat flux regulation further away from the Sun (Halekas et al. 2021; Micera et al. 2021) and the recent observations that ensure the heating of core electrons and ions during the existence of such electrostatic waves (Kellogg 2020; Cattell et al. 2022; Mozer et al. 2022, 2023b). Employing the theory and multi-fluid simulations for both ion and electron acoustic instabilities (Kakad et al. 2013; Kakad & Kakad 2019; Afify et al. 2023) in plasma regimes compatible with PSP observations gives reasonable results. However, this study will be complemented by kinetic simulations with a fully kinetic code that implements solar wind plasma expansion self-consistently, EB-iPic3D (Innocenti et al. 2019), since the fluid analysis is unable to address the contribution of resonant electrons when the wave phase velocity is close to the electron thermal velocity. Indeed, the fluid simulations can capture decently the linear stage of these instabilities while becoming less accurate in the nonlinear stage (Kakad et al. 2014). This study highlights many phenomena, such as the mechanism behind the onset and propagation of different time domain structures such as electron and ion acoustic waves, how they modify the electron-ion velocity distribution functions, and the heating of the core electrons and ions.
Evaluation of Ozone Profile and NO2 vertical column densities of Geostationary Environment Monitoring Spectrometer (GEMS) in China
Authors: Ahmad Naveed , Lin Changqing , K.H. Lau Alexis , Kim Jhoon , Qin Kai , Li Chengcai , C.H. Fung Jimmy
Published: March 2024

Ozone (O3) and nitrogen dioxide (NO2) are critical atmospheric trace gases due to their role in air quality, oxidative chemistry, and climate forcing. Both O3 and NO2 were formerly monitored from space on a daily basis using sun-synchronous polar orbiting satellite instruments. However, the Geostationary Environment Monitoring Spectrometer (GEMS) now provides hourly measurements during the daylight hours over East Asia. Since GEMS is a newly launched satellite instrument, to check the accuracy and uncertainties associated with the first version of its dataset, there is a need for its evaluation through ground-based instruments over the Chinese region. This study presents the systematic evaluation of GEMS hourly measurements of Column Amount NO2 (NO2 VCDs) and Ozone Profile (O3P) by using ground-based measurements. The MAX-DOAS measurements were conducted in Xuzhou in eastern China for one week of each of the four seasons in 2021 to have a better representation of both high and low NO2 concentrations. NO2 variations were well captured in all seasons by both instruments, with higher VCDs in winter and lower during the summer.  A good correlation (R = 0.82) between MAX-DOAS and GEMS was found. However, GEMS underestimated the NO2 VCDs with a consolidated mean deviation (without seasonal discrimination) by -1.87 ± 8.73 x 1015 molec/cm2. The comparison of hourly GEMS NO2 VCDs with in-situ measurements available across China for 2021 has shown a good correlation coefficient of around 0.4-0.6 and higher, particularly in the highly polluted region of the North China Plain. Then, to evaluate the GEMS ozone profile, we used Ozonesonde measurements available for 2021 in Hong Kong, situated in the southern part of China. For the vertical profile of ozone in the troposphere and lower stratosphere, GEMS and Ozonsonde depicted a similar pattern. However, in the troposphere, the Ozonesonde measurements were slightly underestimated, while in the stratosphere, GEMS showed underestimation. It is pertinent to mention that both instruments depicted peak ozone concentrations at an altitude of around 24 to 27 km. The correlation between the two instruments was good, particularly in the lower troposphere (R = 0.74) at 4 km. Further, the lowest layer of the GEMS ozone profile was compared with in-situ measurements for 2021 across the entire Chinese region, and a good correlation coefficient (R: 0.4 - 0.6) was observed. These findings are meaningful scientific advancement enhancing our understanding of the potential of the first geostationary satellite instrument to monitor atmospheric trace gases (O3 and NO2) hourly. More robust validations are recommended in other regions to understand the uncertainties associated with the local conditions and to further improve the GEMS products in future versions of datasets.
Groundwater level reconstruction using long-term climate reanalysis data and deep neural networks 
Authors: Chidepudi Sivarama Krishna Reddy , Massei Nicolas , Jardani Abderrahim , Henriot Abel
Published: March 2024

Assessing long-term changes in groundwater is crucial for understanding the impacts of climate change on aquifers and for managing water resources. However, long-term groundwater level (GWL) records are often scarce, limiting understanding of historical trends and variability. In this study, we present a deep learning approach to reconstruct GWLs up to several decades back in time using recurrent-based neural networks with wavelet pre-processing and climate reanalysis data as inputs. GWLs are reconstructed using two different reanalysis datasets with distinct spatial resolutions (ERA5: 0.25◦ x 0.25◦ & ERA20C: 1◦ x 1◦) and monthly time resolution, and the performance of the simulations was evaluated.  Long term GWL timeseries are now available for northern France, corresponding to extended versions of observational timeseries back to the early 20th century. All three types of piezometric behaviors could be reconstructed reliably and consistently capture the multidecadal variability even at coarser resolutions, which is crucial for understanding long-term hydroclimatic trends and cycles. GWLs’multidecadal variability was consistent with the Atlantic multidecadal oscillation. From a synthetic experiment involving a modified long-term observational time series, we highlighted the need for longer training datasets for some low frequency signals. Nevertheless, our study demonstrated the potential of using DL models together with reanalysis data to extend GWL observations and improve our understanding of groundwater variability and climate interactions. 
 Effects of paleosol on collapsibility of loess sites under immersion test conditions
Authors: Lin Li
Published: March 2024

The presence of multiple layers of red paleosol in loess strata poses challenges due to its high hardness, which hinders easy collapse when encountering water. This characteristic significantly affects the measurement results of the collapsible amount of loess strata. However, there is currently a lack of reports on the control effect of paleosol on collapsibility, resulting in a deficiency in the theoretical basis for the scientific selection of collapsibility in these strata. This paper aims to address this gap by analyzing the differences in self-weight collapsibility between indoor and outdoor conditions under various paleosol layers in different areas and strata. The analysis is based on statistical results from immersion tests conducted in the Loess Plateau. Furthermore, the research focuses on two test sites in Xi'an and conducts large-scale immersion tests, considering measurements such as water diffusion, changes in water content, soil pressure, and cumulative collapsibility under different test conditions. The study investigates the influence of paleosol layers on water infiltration and their role in controlling total weight collapse.The final results indicate that the presence of a paleosol layer prevents collapsibility from transferring to the lower layer and inhibits water infiltration, thereby reducing total collapsibility. Discrepancies between measured and calculated collapsibility values are positively correlated with the number of ancient soil layers. This research provides valuable insights into the collapsibility mechanism of paleosol-loess strata.
Degassing from The Nord Stream Leaks as seen from space : an analog for submarine volcanic eruptions. 
Authors: de Michele Marcello , Carazzo Guillaume , Raucoules Daniel
Published: March 2024

Submarine volcanic activity, constitutes a significant portion of Earth's volcanic events and presents challenges for direct observation due to its predominantly deep-sea occurrence. Despite the rarity of direct observations, insights garnered from shallow eruptions and hydrothermal vents aid in understanding these phenomena. Here, we use the Nord Stream 2 gas leaks in the Baltic Sea region as an analogue to investigate the link between gas emissions at depth and surface manifestations, akin to shallow submarine volcanic degassing. Our study focuses on the mechanical interaction between gas bubbles surfacing from the Nord Stream 2 incident and the resultant sea waves measureable with Sentinel-2 satellite data. We explore the capability of this optical sensor to measure wave celerities and directions generated by the gas plumes impacting the sea surface, inferring gas flow rates at the source. Through a combination of theoretical modeling and satellite-based observations, we measure the kinematic of concentric waves resulting from gas bubble surfacing, presenting a novel method to estimate gas flow rates. Analysis of wave celerities suggests an equilibrium regime, enabling the derivation of gas output rates at depth. Our findings indicate that Sentinel-2 satellite-based measurements can capture and characterize surface waves, offering indirect insights into the dynamics of submarine volcanic gas emissions. We determine a flow rate range of 265 to 400 m³/h, translating to methane gas emissions of 630 to 950 tons/h if considering a source at 70m depth. Furthermore, the use of high-resolution optical satellite missions extends beyond this particular study, holding promising capabilities of detection and characterization of degassing events associated with submarine volcanic eruptions, such as those observed near Mayotte island. The application of our method offers a broader spectrum of observational tools for studying submarine degassing phenomena and complements strategies recommended by the International Methane Emissions Observatory (IMEO) for methane emission characterization. Our study adds up to the methods that advances our understanding of underwater degassing processes and also holds implications for early volcanic unrest detection and risk assessment.  Figure 1. Location of the study area and zooms on the gas leak. Contains modified Sentinel-2 data [2023]. 
Exploring the effect of vegetation photosynthesis phenology on wildfire dynamics
Authors: Lai Gengke , Li Jialing , Wang Jun , Wu Chaoyang , Zhang Yongguang , Zohner Constantin M. , Peñuelas Josep
Published: March 2024

2023 has witnessed a record-breaking extreme wildfire season in Canada from coast to coast, following closely to the unprecedented wildfire outbreaks in 2019/20 Australia and 2021 Siberia, causing far-reaching threats on terrestrial carbon stock, air quality, and human society. The heightened wildfire activity in specific regions prompts us to rethink the underlying factors driving the global wildfire dynamics. Climate change has been recognized as an important factor in amplifying wildfire risk, mainly through increasing temperature and reducing relative humidity. However, the role of vegetation productivity and phenology on wildfire dynamics remains elusive, even though which can exacerbate or mitigate the climate-induced fire risk. Importantly, changes in vegetation phenology can cause biophysical feedback to the climate system and land surface by modulating the exchanges of water and energy between land and the atmosphere. Considering the climate feedback of vegetation phenology, we hypothesize that peak photosynthesis timing (PPT) can contribute to wildfire activity. To explore it, we provide comprehensive analyses using multiple satellite-based photosynthesis observations from solar-induced chlorophyll fluorescence (SIF), and wildfire activity from national fire perimeters and MODIS global burned area records from 2001 to 2018, as well as diverse methodologies and models. In response to changes in various biological and climatic factors, we find PPT has advanced 1.10 ± 0.57 days per decade at a global scale. This earlier PPT acts to expand the extent of wildfires, with an increase in the global average burned fraction by 0.021% (~2.20 Mha) for every additional day of PPT advancement. Satellite observations and the Earth system modeling consistently reveal that this expansion is attributed to the intensified drought conditions during the potential fire season, induced by the earlier PPT that can modulate the global patterns of temperature, precipitation, and surface soil moisture. Furthermore, current fire-vegetation models participating in the FireMIP project underestimate the sensitivity of burned area to PPT, despite reproducing their negative correlation. Our findings highlight the importance of climate-vegetation-fire feedback loops in future prediction of wildfire dynamics and the strategy of climate change adaptation and mitigation.
Evaluation of supraglacial lake depth estimation techniques using Sentinel-2, ICESat-2, TanDEM-X, and in situ data, along with an analysis of rapid drainage events over Northeast Greenland
Authors: Lutz Katrina , Sommer Christian , Humbert Angelika , Braun Matthias
Published: March 2024

Supraglacial lakes are dynamic hydrological features that play a significant role in surface mass balance estimations. These lakes act as conduits for surface and subglacial runoff, the amount of which varies quite strongly based on the local surface temperature, rainfall, and snowpack thickness. Additionally, supraglacial lakes tend to undergo impactful events called rapid drainages, during which a crack opens at the lake bed, draining the meltwater to the glacier bed within hours or days. Not only does this contribute to glacier mass loss and freshwater influx into the ocean, but it can also cause temporary glacier speed-ups due to the reduction of friction on the glacier bed. Currently, the influencing factors involved in triggering these rapid drainages are minimally understood. This research firstly focuses on the comparison of several lake depth estimation methods in order to be able to accurately monitor seasonal lake development and quantify meltwater volumes. Secondly, the temporal and spatial variances in rapid drainages in Northeast Greenland, specifically over Zachariae Isstrom and Nioghalvfjerdsfjorden (79N Glacier), are evaluated in order to understand underlying causes and to quantify the amount of meltwater lost through them. Several established and novel supraglacial lake depth estimation methods are evaluated in this research, comprising of (1) a radiative transfer model based on Sentinel-2 data, (2) an empirical equation derived from ICESat-2 lake crossings and Sentinel-2 data, (3) an empirical equation derived from in situ sonar data gathered in Northeast Greenland and Sentinel-2 data, and (4) TanDEM-X elevation data. These four methods are directly compared on five supraglacial lakes in Northeast Greenland, highlighting the advantages and limitations of each method. Furthermore, the three methods based on Sentinel-2 imagery are applied to the peak melt dates in Northeast Greenland over the 2016 to 2022 melt seasons to understand seasonal variations. Finally, individual lakes are tracked throughout the seven melt seasons to allow for a detailed assessment of rapid drainage occurrences in the region. Overall, insight into the behavioral patterns and influencing factors involved with the rapid drainages of supraglacial lakes and the amount of meltwater lost from them has been gained. 
Biochar enhanced microbial carbon use efficiency, while reducing mineralization of added and native soil organic carbon
Authors: Karhu Kristiina , Kalu Subin , Seppänen Aino , Mganga Kevin , Sietiö Outi-Maaria , Glaser Bruno
Published: March 2024

Biochar can increase long-term soil organic carbon (SOC) storage due to its polyaromatic structure. In addition to the recalcitrant carbon (C) contained in the biochar itself, biochar can also increase SOC storage by adsorption or organic matter on its surfaces, and reduced decomposition rate of native SOC (negative priming). Limited number of studies have looked at how biochar affects decomposition and stabilization of fresh C inputs, and native SOC decomposition. To fill this knowledge gap, we conducted a laboratory incubation study, where we followed the fate of added 13C-labeled glucose in a fine-textured agriculturally used soil (Stagnosol) amended with two different biochar levels corresponding to 15 and 30 Mg ha-1 in field conditions. Biochar addition reduced mineralization of SOC and added 13C glucose, while increasing microbial biomass and microbial carbon use efficiency (CUE). Most of the added biochar, as well as remaining 13C were found in the free particulate organic matter (POM) fraction after 6 months, indicating that added 13C glucose was preserved within the biochar particles. Our closer study of 13C amino sugar fraction extracted from the biochar particles revealed that the microbes that had efficiently grown on the added 13C glucose in the presence of biochar, were retained as dead microbial residues inside the biochar pores. This microbial route could provide a way for additional formation of rather recalcitrant C in the form of microbial residues in the presence of biochar, which could with time contribute to building SOC stock in biochar amended soils beyond the C present in biochar itself. We found that biochar also increased the portion of occluded POM in the treatments without 13C glucose addition, demonstrating that increased soil occlusion following biochar addition reduced SOC mineralization. The effects were found to be dose-dependent, i.e. higher biochar application rate resulted in lower mineralization rate of native SOC and of added 13C-glucose.
The entanglement of microorganisms and mineral matrices in a hyperarid environment – observations by SEM imaging and biomarker analysis from the Atacama Desert
Authors: Prater Isabel , Mißbach-Karmrodt Helge , König Kathrin , Friedrich Daniel , Heim Christine
Published: March 2024

In hyperarid deserts like the Atacama Desert, biota face additional aggravations beside the dryness, e.g. high UV radiation and often high surface temperatures. However, even under these extreme conditions, diverse microbial communities thrive on and within the sediment and interact strongly with their mineral substrate. Common habitats for microbial communities in this environment are fog-receiving surfaces and endolithic zones within evaporite crusts. Endolithic microorganisms are highly adapted to both the substrate and severe water limitations and colonize protected cracks, niches, and caverns within translucent rocks and crusts. They have the potential to alter mineral components and stimulate the formation of secondary minerals as they redistribute moisture and potentially extract crystal water. Processes like these are the starting point of pedogenesis and, even if proceeding extremely slowly, affect the shape of the surface.To elucidate the relationship of microbial communities with the mineral matrix, we investigated the biogeochemical traces of microbial communities and their spatial distribution on and within gypsum and halite crusts from different regions within the Atacama Desert in Northern Chile. We combined imaging techniques (scanning electron microscopy, SEM) and biomolecular methods (gas chromatography-mass spectrometry, GC-MS/MS and nuclear magnetic resonance, NMR) to obtain a deeper insight into the entanglement of microorganisms and evaporitic crusts. Tight interactions of bacteria and fungi with the mineral matrix were revealed by SEM. Short-chain membrane fatty acids (C14-C18) indicated recent bacterial activity in all samples analyzed. Extracellular short-chain acids (C6-C12) and carbohydrates of the extracellular polymeric substances (EPS) make up to 75% of the total biomass within evaporites which point to efficient desiccation buffers and protection mechanisms against UV radiation. Furthermore, the sticky EPS leads to the biochemical stabilization of mineral aggregates by agglutination, which was also visible with SEM.
Time matters: photosynthetic vs. weathering-induced C drawdown and the role of dust inputs along a one-million-year soil weathering gradient on the Galápagos Islands
Authors: Zehetner Franz , Gerzabek Martin H. , Shellnutt J. Gregory , Chen Pei-Hao , Candra I Nyoman , Huang Kuo-Fang , Lee Der-Chuen
Published: March 2024

The Galápagos archipelago, a chain of islands formed by hotspot volcanism on the Nazca tectonic plate, exhibits a pronounced rock age gradient with distance from the volcanic hotspot from west to east. Here, we investigate chemical weathering along a soil chronosequence (1.5 to 1070 ka) under humid conditions. Our results show considerable loss of base cations already in the early to intermediate phases of weathering (e.g. 95% of Na and 78% of Mg lost from the topsoil after 26 ka) and almost complete loss from the entire profile in soils older than 800 ka. Depletion of Si was less pronounced, with topsoil losses of 24% and 63-68% after 26 ka and >800 ka, respectively. Total weathering flux and associated CO2 consumption rates estimated from profile-scale element losses in this study exceeded catchment-scale estimates reported for other volcanic islands or global averages during the early weathering phase, but were much lower in the intermediate and late phases. Nevertheless, total C drawdown was dominated by soil organic C sequestration (70-90% share) rather than inorganic, weathering-induced CO2 consumption during early pedogenesis (≤4.3 ka), and the relative importance switched in the intermediate and late phases (90-95% share of weathering-induced C drawdown at ≥166 ka). Dust deposition derived from a nearby ocean sediment core was 800 ka). Our results suggest that (1) young volcanic surfaces are very efficient (inorganic and organic) C sinks, (2) the development of thick soil covers at advanced pedogenic stages effectively shields the underlying rocks from further weathering, and (3) dust inputs become an increasingly important biogeochemical factor in such highly weathered environments.
Sewage Derived Microplastic and Anthropogenic Fibre Retention by Integrated Constructed Wetlands 
Authors: Warren Richard , Cooper Richard , Mayes Andrew , Nolte Stefanie , Hiscock Kevin , Tosney Jonah
Published: March 2024

High loads of microplastics and anthropogenic fibres can be discharged from wastewater treatment plants (WWTPs) into surface water bodies. Integrated Constructed Wetlands (ICWs) are potentially well suited to provide a cost-effective mitigation solution at small WWTPs where conventional treatment is prohibitively expensive. ICWs consist of a series of connected ponds (receiving all of their inflow from WWTP effluent) that are planted with diverse native vegetation, and are thus designed to improve downstream water quality. This study aimed to assess the microplastic and anthropogenic fibre retention efficiency of two ICWs (Northrepps and Ingoldisthorpe) in Norfolk (UK) over a 12-month period. Water samples were collected at approximately monthly intervals from the inlet and outlet of each wetland (n = 54) between June 2022 and May 2023, and fine bed sediment samples were collected from the Northrepps ICW (n = 23). Northrepps ICW received on average 351,588 (± 223,986) anthropogenic fibres day-1, with a retention rate of 99.3 %. No seasonal variation was observed in retention efficiency. Ingoldisthorpe ICW intermittently received anthropogenic fibres in low concentrations, with an average of 11,448 (± 518) day-1 and a retention rate of 100 %. Microplastics and anthropogenic fibres were prevalent in sediment samples of the first cell of Northrepps ICW, averaging 10,090 items kg-1 dry sediment, while none were found at concentrations above the limit of detection in the second or third cell. Of the 369 fibres analysed by ATR-FTIR, 55 % were plastic (dominated by polyester). Of the 140 suspected microplastic fragments analysed by ATR-FTIR, 73 % were confidently identified as plastic (mostly polystyrene, polyethylene, or polypropylene). This study demonstrates how ICWs can effectively retain sewage effluent derived microplastics and anthropogenic fibres. However, the accumulation of plastic waste in ICWs may complicate long term management and their cost-effectiveness. Research into the minimum size of the first cell to ensure that microplastics are retained within a small area of the overall wetland is recommended to improve long term management prospects.
Modeling Long-term Dissolved Organic Carbon Patterns Using Environmental Variables     
Authors: Wang Kezhen (Jenny) , Mukundan Rajith , Gelda Rakesh K. , Frei Allan
Published: March 2024

Organic matter (OM) in rivers is an important food source to sustain aquatic ecosystem health. However, in surface water supply systems where chlorination is often used for disinfection, OM is also a precursor for the carcinogenic and mutagenic disinfection byproducts (DBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs). Effective management of OM in rivers to maintain both aquatic ecosystem functions and high water-supply quality requires better understanding of the OM transport patterns, where dissolved organic carbon (DOC) can be used as a surrogate measurement of OM. Analysis of DOC data on a watershed scale to estimate fluxes and to determine long-term trends remains challenging, largely due to the spatial and temporal variations in DOC, and low sampling frequency. To help improve the understanding of DOC sources and export processes, we compared long-term temporal patterns in six watersheds in the New York City (NYC) Water Supply System, which supplies drinking water daily to over 8.5 million people in NYC and one million people in the upstate counties. Firstly, we compared six empirical water quality models for DOC prediction. The models include flow-based linear regression (LM), dynamic linear models (DLMs), LOAD ESTimator model (LOADEST), Weighted Regressions on Time, Discharge, and Season (WRTDS), multiple linear regression (MLR), and general additive models (GAMs). Given the differences in dominant land-use and hydrological conditions in the study watersheds, we found that GAMs produced the most robust results. Secondly, we used GAMs with multiple predictor variables to predict long-term daily DOC concentrations in the six study watersheds, which allowed better trend analysis and flux estimates than using the routine grab-sample data with inconsistent sampling frequencies. Lastly, we compared the relationships between temporal patterns in DOC and watershed features to investigate the regional differences, focusing on the watershed mechanistic processes associated with DOC by parsing out the climate signals from the historical trends. The results show that hydrology plays a larger role on DOC temporal patterns in some watersheds whereas nutrient associated production processes are more important in others. The study presents a better performing approach than the solely hydrology driven models and can inform targeted monitoring strategies for DOC management in water-supply source waters.
Assessing the quality of citizen-science rainfall data based on station setup
Authors: Droste Arjan , Boonstra Marchien , Ten Veldhuis Marie-Claire , Bogert Marit , Schleiss Marc , De Vries Sandra
Published: March 2024

The Delft Measures Rain Citizen-Science programme has been running for several years in the city of Delft, the Netherlands. Within this programme, interested citizens can apply to receive a low-cost Alecto WS5500 weather station, to measure local meteorological parameters in their own garden. Currently there are over 45 of these citizen-science weather stations spread across neighbourhoods in Delft, capturing rainfall variability in different urban microclimates. However, the scientific quality of these specific stations has never been tested, and from previous work we know that rigorous quality assurance is necessary in order to get meaningful (precipitation) data. Thus we have installed 8 Alecto stations in The Green Village outdoors urban climate field lab at the TU Delft. Stations have been explicitly installed in ways that a citizen might do: slightly tilted, next to a wall (simulating the limited open garden space of a Dutch urban residence), on top of a shed as well as free-standing. These different measurement setups, combined with a row of stations installed in the same way right next to one another, allow us to investigate the bias caused by less-than-ideal station installation, as well as systematic errors related to the tipping bucket mechanism and sensor drifts. Initial results show a general overestimation of the Alecto compared to reference stations and radar observations, and a discernible negative bias caused by sheltering effects of plants and, to a lesser extent by walls.
Modern spatial distribution of diverse retrogressive thaw slumps in West Siberia
Authors: Nesterova Nina , Tarasevich Ilya , Leibman Marina , Kizyakov Aleksander , Nitze Ingmar , Grosse Guido
Published: March 2024

Regressive thaw slumps (RTSs) are permafrost landforms formed by the thawing of ice-rich permafrost or the melting of massive ground ice. The West Siberian Arctic (Yamal and Gydan peninsulas) is an area with widespread distribution of RTSs due to continuous permafrost and massive tabular ground ice close to the surface. The initiation of RTS in the region strongly affects the environment by altering vegetation and topography and releasing carbon. Roads and railways are also affected by RTS occurrence.  There is still no complete understanding of the true RTS distribution and its environmental controls in the West Siberian Arctic because of the remote location of the region. A remote sensing technique can be used to enhance our understanding of the characteristics of RTS over a large area. However, automated mapping of RTSs has certain limitations, including the lack of ground truth data, the large number of false-positive detections, and the ambiguity in interpretation. Moreover, the polycyclic nature of RTS development leads to a very complex spatial aggradation with numerous overlapping or nested RTSs. This poses additional challenges for mapping.Based on theoretical and field studies, we developed a classification to capture the main morphological and environmental parameters of RTS nature visible on satellite imagery. To minimize false-positive detections we performed in-detail manual mapping of the RTSs in West Siberia using multiple sources including the ESRI satellite base map, Google Earth satellite base map, and Yandex Maps satellite base map. Each point was classified by several parameters: morphology, spatial aggradation, concurrent cryogenic processes, terrain position, and attachment to the base level. Field experience and data at the key sites, as well as a helicopter-based inventory, helped to perform verification and estimate accuracy.We identified more than 4000 RTSs. The spatial distribution of identified RTSs demonstrates clusters over the western Yamal Peninsula and central-northern Gydan Peninsula. This research aims at a comprehensive analysis of the spatial distribution of classified RTS concerning regional geological, climate, and other available environmental data. Our results are valuable for understanding the nature of this widespread phenomenon in the Arctic.
Active Kinematics of the Greater Caucasus from Seismological and GPS Data: A Review
Authors: Pasquaré Mariotto Federico , Tibaldi Alessandro , Bonali Fabio Luca , Corti Noemi , Pedicini Martina , Gulam Babayev , Nino Tsereteli
Published: March 2024

The convergence between the Arabian and the Eurasian plates resulted in the development of the Greater Caucasus (GC) and the Lesser Caucasus fold-and-thrust belts, separated across most of their length by the Transcaucasian depression. The whole sub-horizontal shortening of the Caucasus was quantified at hundreds of kilometers and, according to several studies, reached its maximum rate in the Miocene-Pliocene. At present, convergence between the Eurasian and African-Arabian plates is still active, producing widespread deformation within the mountain belt and in surrounding regions, as testified to by seismological, paleoseismological and GPS data.Understanding the active tectonics of the Caucasus is of paramount importance for a better assessment of geohazards, especially seismic hazard. Moreover, there is a major concentration of residents in Tbilisi, the capital of Georgia, hosting 1.2 million citizens, and in Baku, the capital of the Azerbaijan Republic, with over 2.3 million citizens; both cities are located in active tectonic basins at the southern foothills of the GC. Hundreds of rural villages are scattered in the mountain regions, and all were built without taking into consideration antiseismic criteria. All the above shows that the Caucasus and Transcaucasus regions are subject to an extreme seismic hazard and risk.Here, we describe the active kinematics of the Greater Caucasus (territories of Georgia, Azerbaijan and Russia) through an integrated analysis of seismological, structural-geological and GPS data. Alignments of crustal earthquake epicentres indicate that most seismic areas are located along the southern margin of the mountain belt and in its north-eastern sector, in correspondence of major, activeWNW-ESE faults, parallel to the mountain range. Focal Mechanism Solutions (FMS) delineate dominant reverse fault kinematics in most sectors of the mountain belt, although swarms of strike-slip FMS indicate the presence of active transcurrent faulting, especially along the southeastern border of the Greater Caucasus. The mountain belt is characterized by dominant NNE-SSW-oriented P-axes. In the central-southern sector, in correspondence of the local collision between the Lesser and Greater Caucasus, P-axes are mainly NNW-SSE oriented. GPS data show dominant motions to the NNW, with rates increasing in eastward direction. All observations are consistent with a component of eastward escape of the central-eastern part of the Greater Caucasus.
Bridging geological and geodetic observations for the 1700 Cascadia earthquake with an earthquake cycle model
Authors: Qin Weilun , Govers Rob , D’Acquisto Mario , Barlow Natasha , Riva Riccardo
Published: March 2024

Subduction earthquake cycles are known to produce distinctive patterns of crustal motion, providing critical insights into the details of plate interface coupling and rupture behavior. Retrieving these patterns in the Cascadia subduction zone poses a significant challenge, particularly because the 1700 great Cascadia earthquake (Mw>=9.0) occurred more than three centuries ago.Previous studies of the megathrust earthquake cycle along the Cascadia margin focused on either the geologically constrained coseismic rupture, or on the present-day interseismic coupling patterns based on geodetic observations. There thus is a gap in the comprehensive understanding of the earthquake cycle, particularly in the integration of available geological and geodetic evidence.Our study aims to bridge this gap and unify the insights preserved in both records. To do so, we develop a three-dimensional viscoelastic earthquake cycle model with realistic slab geometry, crustal thickness, and topography. We simulate the coseismic, postseismic, and interseismic stages of the earthquake cycle by alternately locking and releasing asperities, which are derived from geodetic coupling (Li et al., 2018) and geological rupture (Wang et al., 2013) studies.Our results show a good match to convergence-parallel interseismic velocities from the geodetic observations of McKenzie and Furlong (2021). Considering the subsidence signal in the geological record, a good fit can be obtained by a combination of coseismic slip and early afterslip. We find that our results are largely determined by the slab geometry, although factors like asperity configurations, downdip limits of the slab-crust interface, and mantle viscosity structure influence the model predictions.
Process-based modeling of the streamflow generation in a highly glaciated Alpine headwater catchment since the last little Ice Age (i.e., 1850).
Authors: Hofmeister Florentin , Fan Xinyang , Pfeiffer Madlene , Labuhn Inga , Marzeion Ben , Schaefli Bettina , Chiogna Gabriele
Published: March 2024

The streamflow generation related to snow and glacier melt is particularly sensitive to temperature fluctuations and, hence, highly affected by global warming. However, the non-linear and complex interaction between streamflow contributions originating from snow melt versus glacier melt and being transferred to stream via the subsurface complicates the investigation of climate-induced changes in high-elevation catchments. We used the physically-based hydrological model WaSiM to simulate the climate-induced changes in the streamflow generation in the Kaunertal (Austria), a highly glaciated Alpine headwater catchment. The simulations extend from the last little Ice Age (i.e., 1850) to 2015. Large-scale climate processes of a general circulation model (GCM) were dynamically downscaled with the Weather Research & Forecasting Model (WRF) to the central Alpine region at a 2 km spatial resolution from 1850 to 2015. The WaSiM model parameters were transferred from a WaSiM configuration driven by station data and partly optimized by a manual calibration on observed streamflow. For model evaluation, a multi-objective approach was chosen considering streamflow, SWE, snow cover duration, and glacier mass balances. The hydrological model results showed a good representation of the individual components and seasonal streamflow generation. However, difficulties exist in the spatial representation of the heterogeneous and small-scale differences in the snowpack. In addition, there are limitations in the simulation of glacier evolution using WaSiM over long periods (> 30 years) in highly glaciated catchments, as WaSiM does not contain an ice flow routine that can simulate the glacier dynamics during advance or retreat. Despite the cascade of uncertainties in this complex model chain (i.e., GCM, WRF, WaSiM), the results of the long-term simulation show interesting dynamics and enable an analysis of streamflow generation for periods where no observational data is available. For instance, glacier melt indicates a high dependence on the development of summer temperatures (i.e., JJA). The rising temperatures led to an earlier onset of snow and glacier melt, which shifted the streamflow regime and increased the daily streamflow magnitude, especially from 1995 onwards. The next step will be the comparison of the hydrological model results with those from other headwater catchments in the eastern Central Alps with a different degree of glaciation. The novelty lies in comparing 165 years of simulated streamflow and the contributions from snow and glacier melt. This comparison will validate the transferability and generalizability of the complex model chain and the simulation results.
What is polluting Delhi’s air? A quantitative review from 1990 to 2022
Authors: Guttikunda Sarath , Dammalapati Sai Krishna , Pradhan Gautam , Jawahar Puja
Published: March 2024

“How bad is Delhi’s air quality?” and “What are the main sources of Delhi’s air pollution problem?” are perennial questions in India, despite Delhi being the most studied city. Delhi’s air pollution peaks during the winter months starting with Diwali and post-harvest agricultural waste burning in late October and early November and deteriorates further with lower surface temperatures resulting in an increase in demand for space heating. The pollution levels are the lowest during the monsoon months of July and August, but not negligible. This cyclical nature also overlaps with the overall interest in the topic of air pollution and efforts to address the issue, peaking at the start of the winter pollution episodes, with the most the media coverage (based on the number of articles published), public interest (based on social media activity and google search trends), and political will (based on the number of political statements made). This review of Delhi’s air quality from 1990 to 2022 from data, sectoral, judicial, and institutional perspectives is published as an open access data resource and covers databases and story lines on (a) geography and meteorology (b) changes in ambient air quality (as PM2.5 concentrations) using information from ground measurements, reanalysis fields, and satellite retrievals (c) source apportionment studies (d) sectoral history of road transport, agricultural waste burning, residential (cooking and heating) emissions, open waste burning, construction sector (including brick kilns), road dust, power generation and demand, and diwali fireworks and (e) judicial and institutional engagement. All the data resources collated for this review are accessible @ https://www.urbanemissions.info
Repurposing former underground coal mines by deploying emerging renewable energy and circular economy technologies
Authors: Riesgo Fernández Pedro , Krzemień Alicja , Fidalgo Valverde Gregorio , Marqués Sierra Antonio Luis , Iglesias Rodríguez Francisco Javier
Published: March 2024

This presentation introduces the Research Fund for Coal and Steel (RFCS) GreenJOBS project, which approach is premised on leveraging five competitive advantages of underground coal mines to deploy emerging renewable energy and circular economy technologies:(1) mine water for geothermal and green hydrogen. Geothermal energy is a renewable source that harnesses the heat from inside the earth, in our case, through the water that floods the mines. From a certain depth, the temperature of the subsoil is constant regardless of the season. Thus, a continuous and accessible energy source is available all year round. On the other hand, mine water represents an essential raw material for producing green hydrogen by electrolysis;(2) connections to the grid that can be adapted to inject the electricity produced;(3) large waste heap areas for installing photovoltaic/wind;(4) deep shafts suitable for unconventional pumped hydro storage using dense fluids that has a smaller footprint and higher energy density than conventional pumped hydro energy systems; and(5) fine coal waste for recycling into dense fluids employed by the unconventional pumped hydro storage; artificial substitutes for soils from coal waste and wastes from closely located agricultural industries, coal-fired power plants, and water plants; and rare earths from fine coal wastes.The objective is to provide mining companies with two innovative business plans: a Virtual Power Plant where the energy produced will be sold to the grid or used to power electro-intensive industries or companies with constant energy consumption located close to mines, such as aluminium factories or green data centres; and a Green Hydrogen Plant where renewable hydrogen will be produced by electrolysis of mine water and electricity from renewable sources.
Velocity profile in steady flow with submerged flexible vegetation
Authors: Meng Zekun , Wang Ping
Published: March 2024

Flexible submerged vegetation plays a pivotal role in ecosystem. Exploring the relationship between flexible vegetation deformation and flow velocity distribution is essential due to the complex disturbance caused by the bending characteristics of vegetation in water flow. Previous studies have typically relied on constant drag coefficients to predict vertical velocity distribution. However, the broad range of drag coefficient variability in flexible vegetation presents challenges in coefficient selection. In this paper, the developed prediction model of velocity profile based on multi-factor-dependent drag coefficient is derived by cantilever beam theory, dual-layer averaged velocity model and the relationship between the averaged inclination angle and Cauchy number, and the application of this prediction model is highly favorable. Meanwhile, a new analytical expression for depth-averaged drag coefficient of submerged vegetation with deformation angle and Reynolds number is proposed. These equations can reflect the influence of submergence as well. The findings of this study may provide valuable insights into the variability of drag coefficients and the flow structure with submerged flexible vegetation. And it can serve as a foundational basis for the restoration and management of freshwater ecosystems.
Enhanced daytime secondary aerosol formation driven by gas-particle partitioning in downwind urban plumes
Authors: Cai Mingfu , Ye Chenshuo , Yuan Bin , Zheng Ee , Yang Suxia
Published: March 2024

Anthropogenic emissions from city clusters can significantly enhance secondary organic aerosol (SOA) formation in the downwind regions, while the mechanism is poorly understood. To investigate the effect of pollutants within urban plumes on organic aerosol (OA) evolution, a field campaign was conducted at a downwind site of the Pearl River Delta region of China in the fall of 2019. A time-of-flight chemical ionization mass spectrometer coupled with a Filter Inlet for Gases and Aerosol (FIGAERO-CIMS) was used to probe the gas- and particle-phase molecular composition and thermograms of organic compounds.  For air masses influenced by urban pollution, strong daytime SOA formation through gas-particle partitioning was observed, resulting in higher OA volatility. The obvious SOA enhancement was mainly attributed to the equilibrium partitioning of non-condensable (100.5 μg m-3) organic vapors. We speculated that the elevated NOx concentration could suppress the formation of highly oxidized products, resulting in a smooth increase of condensable (100.5 μg m-3) organic vapors. Evidence showed that urban pollutants (NOx and VOCs) could promote daytime SOA formation by increasing the OH production rate. Our results highlight the important role of urban anthropogenic pollutants in SOA control in the suburban region.
 Aware of Climate Change
Authors: Jagurinoska Ruzhica
Published: March 2024

 Aware of Climate ChangeLifting аwareness for climate change and understanding of environmental issues among students in classroom is essential. GLOBE Pedosphere protocols were integrated into my classroom by teaching methodologies as an innovative approach to enhance climate change education. The Pedosphere, which encompasses the soil as a crucial component of the Earth's system, offers a unique perspective to comprehend climate change.My strategy is to take students out of the classroom and let them be in charge in collecting data by respecting the protocols and practical activities.Practical activities such as soil sampling, analysis, and understanding soil structure, temperature, texture, humidity or soil color as health indicators can elucidate the relationship between soil dynamics and climate change processes. GLOBE visualization system helps the students to explore the relation between elevation and temperature and begin learning how to make important patterns evident in visualizations, or to compare and detect data distinction on the GLOBE net all over the world.Leveraging and comparing data with real-world data by GLOBE Visualisation System make students achieve deeper understanding of environmental processes. New knowledge encourages critical thinking and problem-solving skills among students.By fostering a deeper connection with the Pedosphere, students become informed and proactive contributors to sustainable solutions addressing climate change on a local and global scale.