bluuebunny/crossref_metadata_2025 huggingface dataset:
Amino sugars indicate microbial extracellular polymeric substances (EPS) in soil
Authors: Leme Oliva Rebeca , Bahadur Khadka Umesh , Vogt Carla , Dyckmans Jens , Georg Joergensen Rainer
Published: March 2024

Biofilms are a matrix of extracellular polymeric substances (EPS) produced by microorganisms in several environments. When they form in soils, biofilms provide fitness advantages for the microbial community, but also several other benefits for the soil ecosystem, such as aggregation and improving the water retention of soils. Amino sugars (AS) are thoroughly used as indicators for soil microbial necromass as they are not produced by plants. Further, the origin of galactosamine (GalN), the second most common AS present in soils, has not yet been identified, because unlike other AS such as muramic acid or glucosamine, GalN has rarely been found as cell a wall component. In this study, we hypothesized that GalN would therefore be an indicator for microbial EPS. In order to assess this, we have carried out two incubation experiments with bacterial and fungal species commonly found in soils. In the first experiment, we induced EPS production in two fungal and two bacterial species and determined AS in the cell culture and in the extracted EPS. As a result, we found that not only GalN, but also mannosamine were fully removed from the medium by EPS extraction, showing that they are integral parts of the EPS matrix. In the second experiment, ten bacterial and ten fungal species were incubated either with or without a quartz surface for attachment and also either with a glycerol- or starch-based medium. Following microbial incubation, we extracted the EPS and measured four components: total proteins, carbohydrates, DNA, and amino sugars. We observed EPS composition shifted according to the microbial growth conditions, suggesting that each biofilm component may have distinct functions within the matrix. The presence of a surface, for instance, increased the production of proteins, carbohydrates, and DNA in the EPS fraction, while total AS amounts decreased. Additionally, only the production of EPS-carbohydrates augmented with increasing substrate complexity, while the production of EPS proteins, DNA, and amino sugars decreased under the same conditions. Overall, our results reinforce the significance amino sugars have in the microbial necromass fraction, not only as cell wall components, but also as integral parts of biofilms; calling attention to the importance of biofilms for soil organic carbon stocks in soil.
Land-Atmosphere interactions in urban areas
Authors: Bounoua Lahouari , Ed-Dahmany Noura , Thome Kurtis
Published: March 2024

We model and evaluate the interactions between urban surface physical characteristics and components of the surface climate. We combine Landsat and MODIS data to characterize urban surfaces and describe the vegetation and its phenology in a biospheric model. This presentation focuses on the impacts of urbanization on the terrestrial carbon uptake, surface water runoff, and the surface temperature.
We show that in the continental US (CONUS), the carbon sequestration lost to urban land transformation represents 1.8% of the total. The simulations indicate that impervious surfaces expel about 12% of rainwater as surface runoff compared to only 3.2% over natural lands; and continental-scale summer average monthly mean temperature in cities is 1.9 ° C ± 0.6 ° C warmer than in surrounding rural areas.
Key words: urban temperature, carbon sequestration, surface runoff, urban heat island
 
Fine Characterization of Leafing Phenology to Rainfall Regime Shifts in the Brazilian Atlantic Forest by Optical and Microwave Remote Sensing
Authors: Bell James Bruce , Carnaval Ana Carolina , Michelangeli Fabian , McDonald Kyle
Published: March 2024

Tropical forests are crucial for the global biosphere, but their seasonal dynamics are poorly understood. Seasonally dry forests' green-up follows rainfall, while wet forests with evergreen trees show no such pattern due to sufficient water availability. Optical remote sensing methods struggle to characterize the leafing phenology in wet forests due to insensitivity to water content and cloud interference. Using radar remote sensing data, we can track the cyclical pattern of water content in plant tissues, complementing optical data and improving vegetation classifications. Over evergreen forests, a vegetation index from optical data will therefore likely lag behind microwave data due to decoupling of photosynthesis and water accumulation while seasonal forests may show a smaller lag. To test this, I extracted time series (2019-2021) of vegetation indices (EVI2 and RVI) derived from Sentinel-2 surface reflectance and Sentinel-1 microwave backscatter imagery over 1-ha sampling plots in two common vegetation types in the Atlantic Forest of Brazil: evergreen broadleaf and seasonal semi-deciduous forest in Google Earth Engine (GEE). To characterize seasonality in each forest, I modeled annual variation in canopy green-up and water accumulation as both first-order and third-order harmonic functions in GEE. I found unexpected and large asynchrony (lag) of up to four months between the seasonal green-up (based on the optical index) and water accumulation (based on the microwave index) in both seasonal semi-deciduous and evergreen broadleaf forests referenced from the start of season. Depending on the modeling method used, green-up/water accumulation lag in the evergreen broadleaf forest was actually smaller that the semi-deciduous forest by nearly a month. This suggests that introducing lag information in seasonality may not enhance the differences between forest canopy seasonality patterns already indicated by optical amplitude. Alternatively,it may reveal greater sensitivity of evergreen broadleaf forests than semi-deciduous forests to abnormal meteorological conditions such as El Niño, since I found support for significant declines in total rainfall based on IMERG rainfall estimates over the study region in the last 20 years.
Wildness estimation of large rivers
Authors: Zong Shuo , Sanchez Théophile , Mouquet Nicolas , Pellissier Loïc
Published: March 2024

Wild rivers are an invaluable resource that play a vital role in maintaining healthy ecosystems and providing ecosystem services. These rivers provide habitat for a wide variety of plant and animal species. However, the increasing pressure of human activities has been causing a rapid decline of biodiversity and ecological function. But there is currently no map available that identifies the river segments that remain under good conditions, which would be worth protecting and conservation. The quality of the river in terms of wildness is multidimensional and difficult to measure with simple remote sensing products such as land cover and human modification products. However, by using remote sensing images with machine learning methods, we were able to better improve our abilities to provide a detailed map of river wildness with high spatial resolution. Citizen science, which involves engaging non-experts in scientific research, has become an increasingly popular tool for collecting data and expanding the scope of scientific inquiry. In this study, we combine citizen science, machine learning and remote sensing images to map the wildness of large rivers globally. We built a reference database of annotated images thanks to the contribution of citizen scientists through a web application. The application asks each participant to rank two images based on their wilderness for multiple rounds. Then, the rankings were then used to assign a wildness score to each image using the true skill algorithm. Finally, we used this dataset to train an artificial neural network to identify the wildness of river sections. The performance of the model was evaluated using a preliminary test on a geographically separated subset of the data. This river wildness map will provide invaluable insights for conservation initiatives and enable targeted actions to safeguard and restore the remaining wild rivers. 
Observations and year-on-year increase of warm surface waters entering the Ross Ice Shelf cavity
Authors: Sheehan Peter , Heywood Karen
Published: March 2024

Antarctica's solar-warmed surface waters subduct beneath the region's ice shelves as a result of Ekman forcing. In December 2022, an ocean glider collected unprecedented observations of such waters beneath the Ross Ice Shelf, during a serendipitous four-day foray into the sub-glacial cavity; the glider surveyed the cavity in high resolution between the ice base and a depth of 200 m. During most of this period, a 50 m-thick layer of water with a high chlorophyll concentration, which must have come from the Ross Sea polynya and which has the same properties as waters immediately beneath adjacent sea ice, was in contact with the ice base. Super-cooled water was also sometimes observed to be in contact with the ice base. When warm water was present, temperature in the uppermost 5 m decreased towards the ice base in near-perfect agreement with an exponential fit. When super-cooled water was present, no such decrease was observed. From these observations, we estimate the heat loss from the ocean to overlying ice sheet. From re-analysis output, we demonstrate that Ekman forcing drives a heat into the sub-glacial cavity sufficient to contribute significantly to near-front melting of the Ross Ice Sheet. We further show that there has been an increase in the Ekman heat flux into the cavity over the last four decades (i.e. since 1979); this is driven by an increase in the heat content of the seasonally ice-free waters of the Ross Sea polynya, immediately in front of the ice shelf. Interannual variability of the Ekman heat flux, however, is driven not by ocean heat content, or indeed by sea ice cover, but by interannual variability of the along-front zonal wind stress.
Investigation of sea level variations and trends in the Baltic Sea from geometric and gravimetric observations
Authors: Qiu Fenghe , Gruber Thomas , Pail Roland
Published: March 2024

Geometric and gravimetric measurements both have proven to be robust approaches to analyzing sea level changes. The relationship between them is also worth exploring. In this research, the geometric signal and gravimetric signal as well as volume variations in Baltic Sea are compared during the period from 2002.4 to 2016.12. Ideally, the geometric signal should be the sum of gravimetric signal and volume variations, which is so-called sea-level budget. Here, the geometric signal is selected as altimetric data from multi missions combined with in-situ observations from tide gauges. The Mascon solutions are used as gravimetric signals while the volume variations are represented by steric height derived from Baltic Sea Physics Reanalysis model. The Baltic Sea is divided into four regions and the sea level budget equation is applied in each region. The results reveal the gravimetric and volume components exhibit satisfying correlations with geometric signals, which are larger than 0.85 in all four regions. The north region has the least correlation due to the sea ice problem. Furthermore, the comparison underscores the dominance of the gravimetric signal, contributing to approximately 90% of the total sea level change. On the other hand, the sea level trend is estimated by both geometric signal and the sum of gravimetric and volume components. The difference between the two trends in each region is mainly caused by ocean bottom deformation, primarily influenced by glacier isostatic adjustment (GIA). In the processing of mason, the GIA effect is already removed but the geometric signal contains ocean bottom deformation. Therefore, it is necessary to consider the land deformation during the trend comparison. However, because of the sea level equation, the sea level does not change as much as ocean bottom changes, but much smaller. Here we employ the geoid change from NKG2016LU as a trend correction in ocean bottom deformation. The findings contribute valuable insights for predicting sea level changes in the Baltic Sea, emphasizing the significance of accounting for gravitational and volumetric factors along with ocean bottom deformation in sea-level research.
GNSS-based orbit and geodetic parameter estimation by means of simulated GENESIS data
Authors: Arnold Daniel , Miller Alexandra , Kobel Cyril , Montenbruck Oliver , Steigenberger Peter , Jäggi Adrian
Published: March 2024

The ESA GENESIS mission, which obtained green light at ESA's Council Meeting at Ministerial Level in November 2022 and which is expected to be launched in 2027, aims to significantly enhance the accuracy and stability of the Terrestrial Reference Frame (TRF). This shall be achieved by equipping one satellite at approximately 6000 km altitude with well-calibrated instruments for all four space-geodetic techniques contributing to TRF realizations, i.e., Global Navigation Satellite Systems (GNSS), Satellite Laser Ranging (SLR), Very Long Baseline Interferometry (VLBI) and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), and by exploiting the such realized very precise space collocations.The GENESIS satellite is foreseen to carry a zenith- and nadir-pointing GNSS antenna to track (at least) GPS and Galileo signals. Because of its very high altitude, GENESIS will cover much larger nadir angles as seen from the GNSS transmitting antennas, compared to receivers at ground or in low Earth orbit. This will partly result in GNSS observations with lower signal-to-noise ratios. Furthermore, to date, only little reliable information is available on the GNSS transmit antenna gain and carrier phase patterns at very large nadir angles. These problems lead to questions with respect to the best possible exploitation of GNSS data by GENESIS, e.g., whether phase pattern calibrations will need to be performed by means of tracked GNSS data (which would weaken the GNSS contribution to GENESIS).The aim of this study is to assess the impact of GNSS transmit antenna phase pattern errors on the GNSS-based POD of GENESIS, as well as global GNSS network solutions for GNSS orbits and clock corrections, Earth rotation and geocenter parameters and station coordinates based on GNSS observations from GENESIS and terrestrial stations. To accomplish this, we employ simulated GNSS pseudo-range and carrier phase data for GENESIS and ground stations, which have been generated based on detailed link-budget computations and a comprehensive set of transmit antenna gain patterns. The data are used for closed-loop simulation investigations, which allow to compare the reconstructed orbit and geodetic parameter solutions to the simulation truth and offer a quantification of the impact of transmit antenna phase pattern uncertainties on the estimated parameters.
New insights on global fire extremes from object-based fire inventories
Authors: Andela Niels
Published: March 2024

Natural ecosystems are fundamental to biodiversity and reaching net-zero, but are at increasing risk from disturbance events like drought and fire. Across many landscapes, fire responds non-linearly to drought and temperature changes, obscuring evolving fire risk until critical thresholds are breached. In particular, in the absence of natural or human-made barriers, growing fire perimeters result in non-linear increases of daily burned area over the lifetime of any individual fire. Fuel conditions and structure further determine the velocity at which fires can spread across the landscape. Predicting fire extremes remains notoriously difficult due to these non-linear responses and complex interactions of natural and managed landscapes, short observational time-series from satellites, and rapid regional trends in climate and human activity.  One potential new avenue of exploring fire extremes is through the use of novel object-based fire inventories, like the Global Fire Atlas or Amazon Dashboard. Here we use these novel approaches to assess several recently unfolding fire extremes, with special attention to South America. We find that fire extremes can both unfold within a single season or drought year, as well as over the course of multiple years with continued heightened fire activity across a particular landscape. Further characterization of fire types, based on unique characteristics of each fire object, helps better separate climate and land-use driven variability and change in fire extremes. Our results provide novel insights in the underlying mechanisms driving exceptional fire activity, which can inform estimates of future change and land management strategies.
Impact of accumulation rate on firn core water isotopic records from a same region of Adelie Land with high katabatic winds
Authors: Fourré Elise , Orsi Anaïs , Tcheng Titouan , Brückner Louisa , Jacob Roxanne , Lassalle Bernard Coralie , Baubant Léa , Jossoud Olivier , Prié Frédéric , Minster Bénédicte , Agosta Cécile , Leroy-Dos Santos Christophe , Casado Mathieu , Favier Vincent , Magand Olivier , Lemeur Emmanuel , Teste Grégory , Cauquoin Alexandre , Werner Martin , Landais Amaëlle ,   ASUMA raid team
Published: March 2024

Whereas water isotopic records from polar deep ice cores can be interpreted at first order in terms of site temperature, the isotopic signature recorded in shallow cores from Adelie Land (coastal East Antarctica) is less straightforward to decipher (Goursaud et al. 2017, 2019; Leroy-Dos Santos, PhD 2021, 2023). The origin of moist air masses bringing precipitation, the influence of blowing snow, redistribution or sublimation strongly imprint the isotopic signal recorded in firn cores of this region where katabatic winds blow hard. Nonetheless these firn archives are our best way to reconstruct the recent past climatic trend and variability in this area where meteorological monitoring is very sparse and recent.
In this study we compare the water isotopic profiles from firn cores (20 to 70m deep) drilled only a few kilometers apart, in the so-called “D47” area, about 150km inland from Dumont d’Urville at an altitude of 1500m. This site is characterized by very strong katabatic winds and mean accumulation rates can locally vary by several tens of percent. We can thus investigate the effect of very locally different deposition conditions on the isotopic records while the recorded regional climate is the same.
Mapping the extent and land use intensity of shifting cultivation with Planet Scope imagery and deep learning in the Democratic Republic of Congo 
Authors: Yang Wanting , Tong Xiaoye , Li Sizhuo , Ortiz Gonzalo Daniel , Fensholt Rasmus
Published: March 2024

Shifting cultivation, in which primary or secondary forest plots are converted into agriculture for one to two years and then left fallow, is often deemed responsible for tropical deforestation. However, the general attribution of deforestation to areas under shifting cultivation is debatable if considering also the component of forest regrowth during the fallow phase, which is an essential part of a mature shifting cultivation system. Yet, little is known about the extent of small-size cropped fields and fallow stages, which are needed to derive information about the temporal development between small-size cropped fields and fallow in shifting cultivation landscapes.The primary objective of our study is to develop a deep learning-based framework to quantify land use intensity in tropical forest nations such as the Democratic Republic of Congo (DRC) using 4.7-m multi-temporal Planet Basemaps from 2015 to 2023. By employing a convolutional neural network image classification model, we first identified the shifting cultivation landscapes. Secondly, utilizing two-phase imagery, we delve into the temporal development of shifting cultivation, determining whether the landscape continues to be characterized by this practice. Thirdly, the shifting cultivation landscapes were segmented into cropped fields, young fallow, old fallow and old-growth forest/primary forest. Lastly, we used a deep learning regression model to quantify the intensity of shifting cultivation within identified areas. This last step adds depth to our analysis, by offering nuanced insights into the varying practices associated with shifting cultivation practices. Our study in DRC offers a detailed spatio-temporal dataset of the dynamics of shifting cultivation serving as a stepping stone to better understand its impacts on forest loss.
Poroelastic Deformation at Soufrière Hills: A New Perspective on Volcano Deformation Dynamics 
Authors: Alshembari Rami , Hickey James , Pascal Karen , Mantiloni Lorenzo , T. McCormick Kilbride Brendan
Published: March 2024

Volcano deformation studies often neglect the role of the porous, crystal-rich magma reservoirs in modulating surface deformation patterns. Our study examines the current deformation at Soufrière Hills Volcano (SHV) in its ongoing intra-eruptive unrest, with an emphasis on the influence of a mush-dominated, poroelastic magma reservoir. Using 3D finite element models constrained by 14 continuous GPS stations, our findings indicate deformation caused by ongoing melt injection into a low permeability (4.7 x 10-10 m2) reservoir with the injection source located at 16.5 km depth below sea level. Our models show that the melt supply likely decreased linearly from ~1.9 to ~0.3 m3/sec between 2010 and 2022, fitting the recorded decreasing GPS displacement rates. Projective modelling indicates a potential full cessation in melt injection around mid-2024 ± 2 years, but poroelastic melt diffusion will continue, deforming the surface and potentially impacting the stability of the reservoir. Future expansions of this study will incorporate dynamic magma property changes from existing thermodynamic models to represent pressure, temperature and volatile-dependent magma evolution. Our study sheds light on the understanding of deformation patterns at volcanoes, particularly those with crystal-abundant magma reservoirs like SHV.
Helium-isotope data and groundwater ages of 700 shallow and deep groundwater sites in and around the Austrian Eastern Alps 
Authors: Kralik Martin , Brielmann Heike , Humer Franko , Sültenfuß Jürgen
Published: March 2024

Groundwater ages provide valuable insights for water managers and users, helping them understand the timeframe required for water quality improvement measures to become effective and the timeframe in which groundwater bodies are renewed. To estimate groundwater ages in important shallow Austrian aquifers more than 700 tritium/helium-3 analyses and some tracer gas (CFC, SF6) investigations were conducted within the national groundwater monitoring and additional research projects. Noble gases 3He, 4 He and 20Ne were measured at the Institute of Environmental Physics (IUP), University of Bremen, Germany and some at the Isotope Hydrology Section of the IAEA in Vienna, Austria. Groundwater ages vary across Austria and within groundwater bodies due to hydrogeological heterogeneities and depending on gradients of precipitation amounts and recharge rates. They range generally between 0 – 25 yrs. Tritium/helium-3 analyses are an essential tool for groundwater age estimation and the respective piston flow model ages of the shallow aquifers are mostly in the range of 0 – 15 years. However, the missing correlation with the sampling depth indicate partly an internal mixing in the observation wells due to large screen lengths.The existent of elevated 4He-concentrations in aquifers with low background U and Th-content are good indicators of the admixture of old groundwater or just increased 4He-fluxes. The 4He concentrations range from air-equilibrium up to 1.6E-03 (cm3 STP /kg).  The 3He/4He- ratio decreases down to 8.0E-08. Preliminary studies of increased 4He-data with major tectonic fault zones indicate a positive correlation. Clear indications of the admixture of mantle helium were discovered at the end of Eastern Alps toward the western border of the Pannonian Basin. [1]        Kralik, M., Humer, F., Fank, J., Harum, T., Klammler, D., Gooddy, D., Sültenfuß, J., Gerber, C., Purtschert, R. (2014): Using 18O/2H, 3H/3He, 85Kr and CFCs to determine mean residence times and water origin in the Grazer and Leibnitzer Feld groundwater bodies (Austria). Applied Geochemistry, 50 (2014), 150-163 http://dx.doi.org/10.1016/j.apgeochem.2014.04.001[2]        Bundesministerium für Land- und Forstwirtschaft, Regionen und Wasserwirtschaft, Grundwasseralter 2009-2021, Wien (2022). (https://info.bml.gv.at/themen/wasser/wasserqualitaet/grundwasser/grundwasseralter2019-2021.html)
Atmospheric deposition of local mineral dust delivers nutrients to the ‘Dark Zone’ of the Greenland Ice Sheet
Authors: McCutcheon Jenine , McQuaid James , Canha Nuno , Barr Sarah , Lutz Stefanie , Roddatis Vladimir , Mayanna Sathish , Tedstone Andrew , Tranter Martyn , Benning Liane
Published: March 2024

The ‘Dark Zone’ refers to a region of low-albedo ice currently prominent along the western margin of the Greenland Ice Sheet (GrIS). The Dark Zone hosts pigmented glacier ice algae that bloom on the ice surface, thereby contributing to darkening and melting of surface ice. These pigmented glacier ice algae grow in association with other impurities found on the ice surface, namely mineral dust. Mineral dust provides inorganic nutrients to the ice surface habitat in the Dark Zone. As such, constraining the abundance, composition, source, and deposition rate of mineral dust is important for understanding the role of mineral dust in glacier ice algal bloom development and thus the further development of the Dark Zone in other areas of Greenland. Here we characterize the mineralogy, geochemistry, and deposition rates of airborne mineral dust delivered to a site in the SW-margin of the Dark Zone during two field campaigns. Mineral dust delivered by both dry deposition and snowfall was composed of very fine-grained (< 1 µm diameter) silicate mineral fragments, and based on the rare Earth element (REE) signature the dust was primarily from local Greenlandic sources. Potential emission sensitivity (PES) hindcast simulations produced using the Lagrangian FLEXible PARTicle (FLEXPART) dispersion model indicated that PES values were highest over Greenland, thereby corroborating the REE geochemical results by indicating that the sampled aerosols were more likely derived from locations above or near Greenland than more distal locations. The deposited mineral dust contained low concentrations of phosphorus, present in the mineral apatite (Ca5[PO4]3[Cl/F/OH]), confirming that atmospheric deposition of mineral dust provides a mechanism for delivering phosphorus to the Dark Zone of the GrIS, thereby fertilizing the glacial ice algal blooms growing on the ice surface. Our findings have crucial implications for the current and future development of glacier ice algal blooms in this region as well as their role in albedo reduction and surface melting across Greenland in a future warming climate.
Lagrangian transport in a multiple-inlet coastal system: the difference between using 3D and depth-averaged currents 
Authors: Duran-Matute Matias , Fajardo-Urbina Jeancarlo M. , Giesbergen Mart , Gräwe Ulf , Clercx Herman J.H. , Gerkema Theo
Published: March 2024

Transport time scales in estuaries quantify the flushing of the system and are relevant quantities that help to monitor their local and system-wide functioning. Here, we elucidate and quantify the main differences on transport time scales and other related statistics when using passive particles advected by either 3D or depth-averaged currents in an estuarine system. We further relate these differences to the forcing, in particular, wind and freshwater discharge. The analysis is made in the Dutch Wadden Sea: an estuarine system of intertidal basins. Due to computational constraints when using high-resolution 3D currents, we consider two years with contrasting forcing conditions, which were selected after analysis of results based on depth-averaged currents over 36 years (1980-2015). During periods with strong southwesterly winds, mainly related to the stormy seasons (autumn-winter), similar values for the system-wide residence time are found when using 3D or depth-averaged currents. During periods with weak winds, mainly occurring during spring-summer, the residence time computed from depth-averaged currents overestimates the values from 3D currents up to 5-10 days. This was also the case for the anomalous winter of 1996, which is a famous period in the North Sea region due to its low temperatures and lack of strong southwesterly winds. During these weak-wind periods, the difference in the residence is positively correlated to the freshwater discharge. However, despite these observed differences, the temporal variability of the system-wide residence time in the Dutch Wadden Sea is well captured when using depth-averaged currents, i.e., larger residence time during weak wind conditions and smaller during strong wind conditions are observed when using either 3D or depth-averaged currents.
Nicaragua seismicity study in terms of entropy fluctuations in natural time domain
Authors: Flores-Marquez Elsa Leticia , Zambrana-Areas Xochilt Esther , Ramirez-Rojas Alejandro
Published: March 2024

Nicaragua is located on the western margin of the Caribbean plate near its interaction with the Cocos plates. The Caribbean plate is surrounded by four major tectonic plates: Cocos at the southwest, Nazca at the south, the North American and South American to the north and southeast respectively. The Cocos plate subducts the Caribbean plate at rates of aproximately 70 to 90 mm/yr having a steeper dip around 75° and 80°. The Central American subduction zone is seismically active. The associated volcanic arc consists mainly of basaltic-andesitic quaternary volcanic rocks (predominantly pyroclastic and lava flows). The seismicity, although constant, has not exceeded earthquakes of Ms 7.3. We analyzed the period between 2000 and 2023 in terms of entropy in natural time domain. Our analysis in terms of Gutemberg-Richter law shows b-value fluctuation ranging between 0.53 and 1.03 by year. Regarding the analysis of entropy fluctuations, it indicates the correlations are short-range, so we consider that the seismic sequence behaves as a Markovian process.
An Acoustic-Seismo Station for Detection and Early Warning of Debris Flows in Chile
Authors: Palma Lizana Jose Luis , Bello Oscar
Published: March 2024

In 1985, more than 23,000 people died in the town of Armero, Colombia, as a result of a volcanic debris flow (lahar) generated by an eruption of the Nevado del Ruiz volcano. During the 1964 eruption of the Villarrica volcano in Chile, a lahar claimed the lives of 22 people upon reaching the town of Coñaripe. Globally, lahars have resulted in a loss of life and a substantial impact on infrastructure and economic livelihoods. Additionally, the occurrence of non-volcanic debris flows in Chile, such as the Santa Lucía debris flow in December 2017, has highlighted the need for monitoring tools and early warning systems that can reduce risk and ultimately minimise the impact on populations. However, in Chile, there is no appropriate and specific technology for monitoring, detecting, and alarming the occurrence of debris flows. The most significant challenges in developing and implementing such a system are as follows: 1) the components are expensive and must be imported; 2) experts are needed to build monitoring stations and process data; 3) there is a requirement to develop new detection algorithms; and 4) there are no protocols to integrate these types of stations into an early warning system that includes collaboration among different institutions.
 
Research on technologies for the detection of debris flows and other gravity currents based on infrasound and seismic measurements indicates that it is possible to implement an innovative, low-cost, and effective technology for the detection and early warning of debris flows. Some of the most important conclusions from previous research include: 1) the use of infrasound arrays is a suitable and convenient methodology for detecting the occurrence and progress of debris flows, offering significant advantages over other methods; 2) infrasound arrays can detect debris flows several kilometres away, increasing the time between detection and alarm, allowing people to move away from inundation areas; and 3) field studies of the deposits generated by the lahars associated with the 2015 eruption of the Villarrica volcano confirm observations made with infrasound arrays and seismicity.
 
This presentation describes the design of a monitoring, detection, and early warning system for debris flows, including infrasound and seismic sensors; data digitisation, processing, and communication; and the necessary processing algorithms to generate an effective detection and alert. (Note that this is NOT a predictive system requiring the evaluation of meteorological variables.) The equipment includes computational algorithms capable of performing efficient and effective detection, even in the presence of abundant atmospheric noise. Examples of its theoretical performance in both synthetic and real scenarios are presented. We acknowledge the support of FONDEF IT21I0086, ANID, Chile.
 
Robust satellite-based tracking of contrail forming regions
Authors: Robion Louis , Meijer Vincent , Speth Raymond , Eastham Sebastian , Barrett Steven
Published: March 2024

Contrails are estimated to be one of the largest contributors to the aviation sector’s climate impacts. A potential mitigation approach is avoiding flying in regions where contrails form and persist by rerouting aircraft above or below these regions.Implementing such contrail avoidance strategies requires accurately forecasting the location of contrail forming regions. Although models exist, their prediction ability is limited by uncertainties in local weather conditions and contrail modeling. Understanding how these limitations affect our ability to predict contrail formation at a regional scale is necessary to improve forecasting of contrail avoidance regions.To address this, we develop an observational inventory of the evolution of contrail forming regions over the United States. By developing a deep-learning algorithm and ensemble Kalman filter, we generate robust contrail detections on geostationary satellite imagery at a 5-minute frequency. Observed contrail forming regions are tracked over their lifespan allowing for the derivation of properties such as lifetime of the region, or rates of formation of contrails. These observed properties are compared to contrail model outputs using numerical weather prediction data, as well as correlated to patterns such as flight traffic density or spatial extent of the region. We also investigate the variability in conditions across the United States which support contrail formation.Direct comparison of model outputs to large-scale high temporal resolution imagery of contrail forming regions will inform our understanding of contrail formation regions by providing observational evidence as to when and why current predictions can succeed.
Array seismologic insights into Skaftá jökulhlaups (GLOFs), Iceland, 2014-2016.
Authors: Dietrich Thoralf , Eibl Eva P.S. , Pálsson Finnur , Magnússon Eyjólfur , Schwanghart Wolfgang , Ohrnberger Matthias , Heimann Sebastian , Lindner Fabian , Roessner Sigrid
Published: March 2024

GLOFs, glacier lake outburst floods – or by their local type name jökulhlaups – sometimes travel and propagate subglacially. Usually, these subglacial floods can be observed only indirectly using records of the related glacier’s surface deformation derived from GNSS and InSAR techniques. However, these floods can also be monitored by the seismic signals they generate: Flood noise by turbulent water or carried sediments, ice quakes, and others.
At Iceland’s Vatnajökull glacier, floods from the Skaftá cauldrons travel more than 40km below the ice before feeding into the Skaftá river. To study the propagation and the physics of the jökulhlaups, temporal seismic arrays were installed close to the glacier terminus, i.e., west and southwest of Vatnajökull between 2014 and 2016. To locate the generated tremor along the flood propagation path, we used two seismic methods: frequency-wavenumber-analysis (fk-analysis) and match field processing (MFP).
In previous works, we were able to track the subglacial propagation of the flood tremors seismically for four GLOF events occurring between 2014 and 2016. For the discharge-highest flood occuring in October 2015 we were also able to identify seismic signals related to the rising water level downstream at rapids outside of the glacier.
These findings can be directly related to hydrometric and GNSS observations, measured outside and on the glacier respectively. We find that the tremor can be related to the vertical deformation of the glacier after the flood front’s passing: an important insight allowing to reconstruct the glacier’s deformation seismically.
Our results highlight the potential of seismic methods for monitoring subglacial floods, especially in combination with GNSS and hydrometric observations. We emphasize that such multi-method approaches can improve the understanding and quantification of flood characteristics such as their volume, origin, propagation and timing which are critical to effectively provide early warning of subglacial floods.
Assessing Sustainable Approaches to Urban Air Quality: A Study of Malaysia's Largest Conurbation Regions
Authors: Abdul Halim Nor Diana , Latif Mohd Talib , Mohamed Ahmad Fariz
Published: March 2024

The capital of Malaysia has undergone urbanization since the 1980s, which led to the formation of the largest conurbation area, Kuala Lumpur Extended Mega Urban Regions (KLEMUR). This study aims to understand the long-term air quality trends in KLEMUR, particularly concerning land use changes. Statistical and geostatistical analysis in the Geographic Information System (GIS) was used to analyze air pollutants (PM10, O3, NO, NO2, NOx, CO, and SO2) and land use data (built-up areas, vegetation, and water bodies). The results showed increased trends in air pollutants, except for SO2, which decreased due to improvements in fuel consumption. However, the annual mean concentration of PM10 exceeded both the Malaysian Ambient Air Quality Standard (MAAQS) and WHO guidelines. Despite COVID-19 lockdowns, PM10 concentrations remained above recommended limits. The time series results showed only PM10 and O3 were also influenced by the meteorological conditions during the seasonal monsoon. The Principal Component Analysis (PCA) results demonstrated that 53.61-63.42% of the total variance was influenced by motor vehicles and industrial emissions since the strong factor loadings (>0.70) consisted of NO, NO2, NOx, CO, and SO2. The KLEMUR air quality was predominantly affected by motor vehicle emissions since the NO/NO2 ratio exceeded 2.0. The KLEMUR land use increased in built-up lands (4.0%) and there was a simultaneous reduction in vegetation (3.3%) and water bodies (2.3%), causing the spatial distribution of air pollutants to expand from the centre of KLEMUR to the south and north. The KLEMUR land use has a significant impact on NO, NO2, NOx, CO, and SO2 since the air pollutants are positively associated with built-up lands and negatively associated with vegetation and water bodies. The Geographically Weighted Regression (GWR) model was able to determine that about 80–90% of the KLEMUR air pollution was influenced spatially by the changing of built-up lands and vegetation, while only 20–70% of water bodies influenced the air pollution. A sustainable air quality framework was proposed based on these findings by focusing more on land use changing impacts for sustainable cities and clean air without limiting economic growth.
Relationship between sealing faults, pressure domains and fluid-induced seismicity
Authors: Eaton David , Esmaeilzadeh Zahra , Hosseini Navid , Zeinabady Danial , Clarkson Christopher
Published: March 2024

Sealing faults are nearly impermeable barriers that can form boundaries between subsurface pore-pressure domains. In the case of hydrocarbon systems, sealing faults commonly form part of a structural trap; they are thus likely to be important elements for future storage of CO2, hydrogen, and other gases in depleted reservoirs. The Triassic Montney Formation in British Columbia, Canada hosts low-permeability gas reservoirs containing sealing faults that have previously been assumed to compartmentalize pressure domains within a regional transition from overpressured to normally pressured parts of the basin. In this study, we show that the distribution of induced seismicity associated with hydraulic fracturing (HF) exhibits a statistically significant spatial correlation with zones of high lateral gradient in pore pressure. These high-gradient zones are interpreted as sealing fault systems. The largest induced seismicity sequence, including a 4.5 ML mainshock on 2018/11/30, occurred during HF treatments in two horizontal wells, between which there is an exceptionally large contrast (~ 10 MPa) in measured pore pressure. Numerical simulation of a simplified model of a hydraulic fracture intersecting a nearby vertical fault, followed by fault rupture using a rate-state friction rheology, generates results that are in good agreement with observed strike-slip faulting near one of the HF wells. Our study demonstrates that sealing faults exhibit previously unrecognized behaviour that may be important for understanding induced seismicity risk.
Clearcut effects on the spatial distribution of C and N in the soils of a forested headwater catchment in the Eifel, Germany
Authors: Batsatsashvili Maia , Dedden Lea , Gettel Gretchen , Kalbitz Karsten , Wiekenkamp Inge , Bol Roland , Pütz Thomas
Published: March 2024

Riverine systems are distinct components of the natural environment which have significant roles in storing and processing terrestrial carbon. While processing organic matter, rivers release large amount of greenhouse gasses to the atmosphere. In this light, headwater streams are particularly interesting. Due to their high connectivity with the surrounding landscapes, these small streams are strongly influenced by terrestrial inputs of carbon and nitrogen and groundwater inflow. Therefore, despite smaller surface area, their role in C and N cycling is crucial. The amount and character of C and N inputs to headwater streams is highly dependent on soil and vegetation types of the catchment. Soils, connecting the atmosphere, hydrosphere and lithosphere and supporting various ecosystem processes, are believed to exhibit strong responses to ecosystem disturbances. Among these disturbances are climate change impacts and modified landcover.
The aim of this study is to analyze three-dimensional variability of biogeochemical processes in the soils of a forested headwater catchment, following partial clearcut of a spruce forest.
The high resolved data on soil properties were collected in the Wüstebach catchment (Eifel/Lower Rhine Valley), a long-term environmental observation site of the TERENO (Terrestrial Environmental Observatories) project. The Wüstebach is a forested catchment in which nine hectares of Norway spruce was cleared in 2013 and has been replanted with original beech.
Three extensive soil sampling campaigns were conducted in the catchment: the first just before a partial clear-cut in 2013, the second after the clearcut in 2014 and the third, five years after the clearcut in 2018. The sampling produced high-resolution data on physical and biogeochemical soil parameters per horizon.
The plan of this study is to perform geostatistical analysis of the data and produce three-dimensional surface prediction models of the spatial distribution of the two nutrients: C and N in 2013, 2014 and 2018 over the entire catchment.
Multi-scale variations of ocean temperature off the coast of Nova Scotia 
Authors: Lu Youyu
Published: March 2024

Ocean temperature variations off the coast of Nova Scotia are quantified through analyses of observational data and the simulation results of high-resolution numerical ocean models. The analyses reveal significant variations at various time-space scales, including: 1) rapid colling in nearshore waters associated with extreme cold-air outbreaks; 2) frequent cold spells at seabed along the coast from late fall to early spring; 3) extensive upwelling along the coast from late-spring to fall; 4) marine heat waves and cold spells at surface and in the water column; and 5) large-scale cooling or warming spanning over a season or longer. The forcing mechanisms and predictability of these variations are explored through analysis of atmospheric forcing and ocean model solutions. The potential relevance to applications in marine ecosystems and fishery are discussed.
The Impact of West Somerset Lagoon Operation on Water Renewal of Bristol Channel and Severn Estuary
Authors: Guo Bin , Ahmadian Reza , Falconer Roger
Published: March 2024

A tidal lagoon generates predictable energy from tides by creating an artificial water head difference through impounding water over a tidal cycle. The movement of substantial water volumes between natural waters and the enclosed lagoon basin triggers changes in water exchange and tidal circulation, potentially resulting in significant impact on water quality. Therefore, a comprehensive understanding of the impact of tidal lagoons on regional water exchange is crucial to address any predicted concerns.
The West Somerset Lagoon (WSL) was studied in this study to investigate its impact on water renewal of Bristol Channel and Severn Estuary. The hydrodynamic modelling of lagoon structures used domain decomposition method, and full momentum conservation was achieved by refining the momentum source terms at the turbine locations. To assess the seawater renewal alteration, this study computed water residence time by tracking the evolution of a non-buoyant, mass-conservative tracer concentration which was introduced into a control domain surrounding WSL. The residence time was calculated using the widely adopted 'e-folding time' method, representing the duration for the tracer concentration to decrease to 1/e of the initial concentration. To better understand the influence of WSL on water renewal in distinct regions, tracers were introduced in three separate zones based on geographical divisions: the Severn Estuary to the outer Bristol Channel, the Severn Estuary to the Inner Bristol Channel, and the Severn Estuary itself.
The study investigated water renewal exchange in the study areas before and after the implementation of WSL. The results revealed a 43% reduction in residence time for the entire Bristol Channel and Severn Estuary after the construction of WSL. Furthermore, the inner Bristol Channel and Severn Estuary experienced reductions of 20% and 13% respectively after WSL incorporation into the models. As such, the operation of WSL could potentially accelerate pollution mitigation and attenuation in these areas, with this being a meaningful consideration for future design of similar treatment and retention systems where there are potential pollution and health risks.