bluuebunny/crossref_metadata_2025 huggingface dataset:
Greenhouse gas (CO2, CH4) alteration in shallow ice at Larsen blue-ice area, Northern Victoria Land, East Antarctica
Authors: Lee Giyoon , Ahn Jinho , Oyabu Ikumi , Kumari Kajal , Kawamura Kenji
Published: February 2023

CO2 and CH4 records from polar ice cores have greatly enhanced our understanding of the control mechanisms of atmospheric greenhouse gas (GHG) concentrations and their relationship to surface temperature. However, multiple ice cores show offsets of 1–3 % and concerns about in situ production in trapped air were raised. Recently, GHGs in shallow ice cores from blue-ice areas (BIAs) in Antarctica show excess CO2 and CH4 concentration values and even extremely lower CH4 concentration than other non-contaminated ice core records at the same gas ages. We aim to decipher the processes of GHG production and CH4 destruction in the shallow ice at Larsen BIA. CH4 concentration records from the Larsen BIA generally show an increasing trend from the subsurface to a depth of ~0.35–1.15 m. Then gradually decreases until it reaches the true ancient atmospheric CH4 values at ~4.6 m depth. In contrast, CO2 concentration in the Larsen blue ice shows a gradual decrease from the subsurface until a depth of ~4.6 m where the concentration variation stabilizes, but still has a 10–20 ppm difference with other existing non-contaminated ice core records. These alterations might be due to mixing with modern air through cracks and/or microbial activity inside the occluded air bubbles. The vertical distribution of δ15N-N2 in several Larsen BIA ice cores indicates that alteration by modern atmospheric air is not significant at the top ~10 m. Depleted δ18Oatm in a depth of ~0.15–1.65 m might indicate in situ microbial activity consuming O2 gas in Larsen blue ice samples, but δ18Oatm values in a depth of 1.95–10 m might indicate little microbial activity. Our future study may include analysis of Pb concentration and isotopes to investigate the effect of modern aerosol intrusion. In addition, we may measure CH4 concentration in ice after receiving UV light in order to check whether UV photolysis is included in the mechanism for CH4 destruction.
Developing a regionally refined high-resolution and mass-consistent atmosphere-hydrology de‐aliasing data set for GRACE‐FO and Next-Generation Gravity Missions
Authors: Mielke Christian , Springer Anne , Dixit Shashi , Kusche Jürgen , Friederichs Petra
Published: February 2023

Temporal aliasing of high-frequency mass variations is, next to instrument noise, the biggest obstacle to improving accuracy and resolution of satellite gravimetry products from the GRACE, GRACE Follow-On and next generation gravity missions. In current GRACE/-FO processing, tidal and sub-monthly non-tidal mass variations in ocean and atmosphere are removed from the level-1 data using the Atmospheric Ocean Dealiasing (AOD) data sets. However, these reanalysis- and forecast-based data sets are not perfect and therefore errors are introduced in derived short- and long-term science results. Hence, to a large extent, the quality of the GRACE/-FO level-2 data relies on the consistency of the AOD data. It is therefore an essential task to improve the background models, especially with regard to next generation gravity mission.The research group New Refined Observations of Climate Change from Spaceborne Gravity Missions (NEROGRAV), funded by the German Research Foundation (DFG), aims at improving GRACE/-FO data products by developing new analysis methods and modeling approaches. This includes a revision of existing geophysical background models as well as their spatial-temporal parameterization. Within this research group we create a consistent global data set of short-term atmospheric and hydrological mass variations with higher temporal and spatial resolution over Europe. For computing the atmospheric dealiasing fields we apply the 3D integration approach developed by Forootan et al. (2013) that also accounts for more realistic approximations of the Earth’s physical and geometrical shape. We compared sub-monthly as well as long-term signals of global atmospheric fields from ERA-Interim and ERA5 to investigate differences arising from different spatial resolution (0.5° & ~0.1°). The regional non-hydrostatic atmospheric reanalysis COSMO-REA6 provides 3D fields on a grid sized even below 0.1° within the EURO-CORDEX domain. We nested COSMO-REA6 into ERA-Interim to obtain a global consistent atmospheric dealiasing data set, but with higher spatial and temporal resolution over Europe. Short-term hydrological signals are not included in the standard dealiasing products, yet, some studies indicate that removing them might further reduce aliasing errors in the monthly GRACE/-FO fields and might be inevitable for next generation gravity missions. Therefore, we developed a hydrological dealiasing product following the same approach as for our refined atmospheric data set by nesting the water storage changes derived by the regional CLM data set (forced by COSMO-REA6) into the global WGHM data set. In this presentation we show the impact of short-term mass changes over Europe on GRACE observations.
Two decades of seismicity in the West Iberian Margin: current hypothesis and new ideas
Authors: Fernandez Viejo Gabriela , Lopez-Fernandez Carlos , Cadenas Patricia
Published: February 2023

The analysis of two decades (2003-2022) of seismicity recorded by the Spanish and Portuguese seismic networks along the West Iberian passive margin results in a picture of the clustered and moderate seismicity observed in this intraplate submarine area.The study precise the trend of specific alignments, providing an accurate depiction of event distribution along two stripes 700 km long through the ocean floor in WNW-ESE direction. These alignments are parallel to the Africa-Eurasia plate boundary, but distinctly separated from its related seismicity ≈300 and ≈700 km respectively, enough distance to be considered as intraplate.When trying to relate this seismicity to structural, and/or geophysical features, it doesn’t arise a conclusive picture. The earthquakes occur indiscriminately across thinned continental, hyperextended, and exhumed mantle rift domains. They fade out in the proximity of undisputed oceanic crust, but some events extend beyond. The hypocentral depths signal a considerable amount of events nucleating in the upper mantle. The focal mechanisms are predominantly strike-slip and a superposition of the event map with geophysical data shows a puzzling lack of affinity with any of them.Considering these observations, different hypothesis are discussed to explain this relatively anomalous distribution of seismicity. Some of them previously advanced in the literature do not portray convincing arguments. Others are too unspecific. None of them are completely flawless, suggesting that maybe there is several factors at play. Despite being one of the most probed passive margins in the world, the present geodynamical state of the West Iberian Margin manifested in its modern seismicity, seems to remain unknown.Interpreting these data within a global tectonic plate framework, together with the potential addition of sea bottom seismometers may give the key to understand this activity along one of the most archetypical margins of the Atlantic Ocean.
Characterization of changes in extreme storm surges along the North Atlantic coasts, since 185
Authors: Cheynel Julie , Pineau-Guillou Lucia , Lazure Pascal
Published: February 2023

Severe storms that hit the North Atlantic coasts over the last decades, such as Xynthia storm in Europe, showed the vulnerability of coastal populations to extreme sea levels. There is a need to quantify the changes in extreme sea levels, to enable the implementation of appropriate coastal adaptation measures. Extreme sea levels are the joint contribution of mean sea level, tide and storm surges. Several authors investigated changes in storm surges. Storm surges display strong interannual and multidecadal variability, but no clear long-term trends at most sites globally (Mawdsley and Haigh, 2016; Marcos and Woodworth, 2017). The objective of the present study is to characterize changes in extreme storm surges along the North Atlantic coasts, since 1850. We selected long-term tide gauges with at least 100 years of data, from GESLA-3 dataset (Haigh et al., 2022). This conducted to consider around 30 tide gauges along the U.S. and European coasts. Extreme storm surges were evaluated yearly, using different approaches: (1) the maximum value over a period (e.g. annual maximum), the n-th percentile (e.g. 99th percentile) and (3) the return level associated to a return period (e.g. 1 year return level); this last value is obtained by fitting a Generalized Extreme Value distribution on data. At each station, we characterized changes in extreme storm surges over the last century. We compared the different approaches. We estimated long-term trends and analyzed storm surge variability in link with large-scale atmospheric forcing (e.g. North Atlantic Oscillation index). Regions of similar variations were also identified. These results are a first step towards the understanding of the physical causes behind the observed changes of extreme storm surges in the North Atlantic. References[1] Marcos, M. & Woodworth, P. L (2017). Spatiotemporal changes in extreme sea levels along the coast of the North Atlantic and the Gulf of Mexico. J. Geophys. Res. Oceans 122, 7031–7048. https://doi.org/10.1002/2017JC013065[2] Mawdsley R. J. and Haigh I. D. (2016). Spatial and Temporal Variability and Long-Term Trends in Skew Surges Globally. Front. Mar. Sci. 3:29. https://doi.org/10.3389/fmars.2016.00029[3] Haigh I. D., Marcos M., Talke S. A., Woodworth P. L., Hunter J. R., Hague B. S., et al. (2022). GESLA Version 3: A major update to the global higher-frequency sea-level dataset. Geosci. Data J., 00, 1–22. https://doi.org/10.1002/gdj3.174 
The role of frictional heterogeneities, stress-state and fluid flow on fault slip behavior during fluid pressure perturbations.
Authors: Pardo Silvio , Tinti Elisa , van den Ende Martijn , Ampuero Jean-Paul , Collettini Cristiano
Published: February 2023

In the last 15 years, activities for geo-energy production are associated to subsurface fluid injection in enhanced geothermal systems,  for enhanced oil recovery, for the disposal of wastewater or for carbon dioxide capture and storage. In several regions, M>3 earthquakes occurred following fluid injection, and some of these earthquakes have caused extensive damage, putting geo-energy production projects at risk of being discontinued. Evaluating the conditions under which fluid injection can induce earthquakes is therefore important to safeguard local infrastructures and to ensure continuity of geo-energy projects.  To shed light on the effect of fluid injection on a fault located in the proximity of a reservoir, we implemented into the Q-DYN seismic cycle simulator the fluid diffusion equation (one-way coupling). We ran models of seismic cycles on a rate-and-state-dependent fault under a quasi-dynamic approximation, and we developed a systematic study to assess how fault frictional heterogeneities, the stress state of the fault upon injection, the timing of injection relative to the phase of the seismic cycle and factors controlling fluid flow, i.e. permeability, porosity, flow-rate, influence fault slip behavior and earthquake magnitude. Our results show that localized pore-pressure perturbations allow us to gain deeper physical insight into the propagation and arrest of earthquake ruptures and that changes in the fault physical properties can promote a spectrum of fault slip behavior and recorded magnitudes.
Real-time monitoring of the Russia-Ukraine conflict using seismic and infrasound array data
Authors: Dando Ben D.E. , Goertz-Allmann Bettina P. , Brissaud Quentin , Köhler Andreas , Schweitzer Johannes , Kværna Tormod
Published: February 2023

Since the invasion of Ukraine in February 2022, daily media reports have shown the shocking effects of fighting and the inevitable devastation associated with war. However, getting a comprehensive and unbiased overview of the ongoing military attacks remains a challenge. The availability of geophysical data that can identify individual attacks provides much needed objectivity to this problem. The pressure waves generated by an explosion travel through the atmosphere and subsurface as sound and seismic waves, and their signature can be recorded by arrays of seismometers for ground motion or microbarometers for sound propagation. In this work, we demonstrate the first known case of using seismological data to detect conflict-related explosions in near-real-time. Using the Ukrainian primary station of the International Monitoring System (IMS), the Malin array (AKASG), we automatically locate explosions around the Kyiv and Zhytomyr provinces. We show how our resulting catalogue of explosions correlates with key events in the Ukraine conflict and how these data can be used to both verify and improve accurate reporting of military attacks. We analyze events with a variety of seismo-acoustic signatures and significant differences in explosive yield. These can be associated with various types of military attacks, including artillery shelling, cruise missile attacks and airstrikes. This work opens-up the possibility for future conflict monitoring using geophysical data.
Characterizing the current and future groundwater storages in a highly glaciated catchment : a synthesis of 3 years of field observations and modelling results
Authors: Müller Tom , Lane Stuart N. , Schaefli Bettina
Published: February 2023

Alpine glaciated catchments are rapidly changing with glacier retreat. Combined with future earlier snow melt and more liquid precipitation, the importance of high alpine catchments to provide essential water resources for downstream uses will increase. In this context, groundwater storage may play a critical role in maintaining baseflow during drought events. In this study, we provide an overview of the hydrogeological functioning of the Otemma glacier catchment, a typical glaciated catchment in the Swiss Alps. Based on three years of field data, we provide a complete conceptual model of the volumes and timescales at which different landforms store and release water and compare those results with a catchment-scale analysis of the winter discharge recession. Based on water isotopes and geochemical data, we show the strong spatial heterogeneity in the water sources that recharge those landforms and how they are interconnected. Finally, we present results of a 3D model of the groundwater-surface water interactions in the proglacial outwash plain, discuss where potential new floodplains may form in the future and show a rather limited potential storage of the order of 20 mm. We conclude that superficial landforms have a limited potential to provide significant baseflow for downstream users but can provide significant moisture for high alpine ecosystems. Nevertheless, we show that bedrock infiltration likely represents the largest groundwater reservoir but more research is needed to characterize its role in the future.
The landscapes of southern Africa: the legacy of mantle dynamic or glacial erosion?
Authors: Dietrich Pierre , Guillocheau François , Douillet Guilhem , Griffis Neil , Barrier Laurie , Le Heron Daniel , Montañez Isabel , Robin Cécile , Kettler Christoph , Hofmann Axel
Published: February 2023

The modern relief of southern Africa is characterized by high-standing plateaus surrounded by escarpments and dissected by a network of encased valleys that connect the plateaus to coastal plains. This topography is commonly interpreted as resulting from the activity of a mantle plume, the African superplume, and the resulting stepwise uplift of the lithosphere, generating planation surfaces through surface erosion processes since the Mesozoic. However, in this study, we argue that part of this landscape is inherited from the glacial processes of the Late Paleozoic Icehouse (LPI) that occurred 300 ma ago and during which southern Africa was largely covered in thick ice. Field and GIS-based sedimentological and geomorphological studies however revealed that LPI glacial activity tied to the Late Paleozoic Icehouse, that occurred 300 million years ago and during which southern Africa was largely covered in thick ice, greatly contributed to the shaping of the Earth surface at different spatial scales. Glaciers levelled continental-scale planation surface, carved large valleys, fjords and overdeepenings within topographic escarpments that already existed, ploughed grooves and striae on the bedrock and left behind typical sediments such as moraines, tills and ice-contact deltas. After glacial retreat, the sea invaded these glacial reliefs, as attested by preserved paleoshorelines. In postglacial times and for 120-180 million years, these glacial landforms were progressively filled and eventually sealed under thick non-glacial sedimentary accumulation and was later rejuvenated by erosion tied to the activity of the mantle superplume. Today, large portions of the desertic high-standing plateaus, escarpments and networks of valleys defining the relief of southern Africa actually corresponds to a relict though rejuvenated 300-Ma old glacial landscape.
Participatory System Dynamics modelling for Water-Energy-Food Nexus characterization and for supporting the analysis of management measures
Authors: Coletta Virginia Rosa , Imbò Alessandro , Pagano Alessandro , Fratino Umberto , Giordano Raffaele
Published: February 2023

There is a growing awareness on the existence of dynamic interdependencies between the Water-Energy-Food sectors that cannot be ignored in identifying sustainable sectoral and cross-sectoral policies. In addition, the increasing demand for resources creates trade-offs that are exacerbated by the impacts of climate change, such as drought and flood with increasing frequency and magnitude. The Water-Energy-Food Nexus approach is a powerful concept to address the interrelationships of resource systems and move towards better coordination and utilisation of natural resources, considering existing trade-offs and promoting positive synergistic impacts. However, the incorporation of this approach into policies is making slow progress. This means that a gap exists between science (Nexus thinking) and policy (Nexus doing). The present work, carried out in the framework of the REXUS project (H2020, GA 101003632), aims to develop a process, strongly based on the use of participatory approaches, to support decision‐makers in designing sustainable and actionable forward-looking solutions that increase resilience across sectors. Integrated modelling based on System Dynamics is used for this purpose. In fact, it i) accounts for real-world complexities; ii) allows for future scenarios development and analysis, with clear options for policymakers; iii) allows for the integration of stakeholders’ knowledge.Specific reference is made to one of the REXUS pilots, namely the Isonzo‐Soca watershed between Italy and Slovenia, for which current cross‐border flow regulation agreements are insufficient to guarantee a good status of ecosystem services in the Italian territory. The participatory System Dynamics modelling approach is combined with results of sectoral models, hydropeaking indicators, and ecosystem services indicators for a clear framing of the problem and its effects on the system. Through stakeholder engagement, some strategies for limiting sectoral conflicts are co-designed and fed into the System Dynamics simulation model to assess their effects on the system - and on different aspects (social, environmental, economic, etc.) - under various multidimensional future scenarios. The approach, organised in several steps, is based on a common framework replicable in different study contexts.
Surface runoff estimation in urban areas via remotely sensed greenery and composite curve number
Authors: Schumann Guy J.-P. , Tamagnone Paolo , Suttor Ben
Published: February 2023

Traditionally, flood risk maps used by city officials and water resource managers for urban planning, by engineers for adequate flood defence infrastructure design, or by insurers and re-insurers for estimating financial risk exposure are the result of modelling flood hazard of rivers and their associated floodplain lands at different return periods. Often, any of these stakeholders would use the 1:100 return period of fluvial hazard to plan accordingly. However, with the climate crises signals clearly present during recent flood disasters, and especially with the 2021 Europe floods, water managers, cities and the financial risk sector are now starting to plan differently and are recognizing the need not only for better and more frequently updated flood risk analysis, particularly in urban areas, but also need to consider pluvial and flash floods that can happen in any part of a river basin and oftentimes take place in headwater areas or off the main river floodplains. Flash flooding greatly impacts urban areas where the storm drainage infrastructure is becoming largely insufficient due to the increasing duration and higher frequency of extreme intense rainstorms. Therefore, model simulations of flood hazard that account for these rather unprecedented types of extremely destructive events are required, and those need to be integrating the newest data from all types of sensors. At the same time, we observe that sustainable, nature-based solutions are now sought after because these solutions offer an inviting alternative to ever changing flood risk, particularly under the present and future climate crisis.  It is stipulated that increasing healthy urban vegetation cover could reduce this risk and is a form of a nature-based solution for urban areas. Here we combine existing methods from the literature and develop a methodology relating  time-series of satellite-based vegetation maps, topography and soil permeability to estimate excess runoff from intense precipitation. The runoff coefficient is mapped through the use of a composite curve number method.. The method of looking at  the partition between rainfall and runoff is highly correlated to change in land use, and thus changes in vegetation cover. Relying on the NDVI index for green vegetation mapping, the methodology is able to capture the differences in the hydrological response even for seasonal or canopy integrity changes. Looking at different vegetation cover scenarios therefore allows the creation of different runoff responses, and therefore a possible reduction in flood risk.In this paper, we present initial results of this flood risk analysis, the goal of which is to produce runoff change maps at city, urban neighbourhood or city post code level using different scenarios in rainfall amounts from design storms coupled with existing or planned urban vegetation cover scenarios.
Using path-integrated strain in Distributed Acoustic Sensing
Authors: Trabattoni Alister , Biagioli Francesco , Strumia Claudio , Festa Gaetano , van den Ende Martijn , Rivet Diane , Sladen Anthony , Ampuero Jean-Paul , Metexian Jean-Philippe , Stutzmann Éléonore
Published: February 2023

Distributed Acoustic Sensing (DAS) is becoming a well-established technology in seismology. For historical and practical reasons, DAS manufacturers usually provide instruments that natively record strain (rate) as the principal measurement. While at first glance strain recordings appear similar to particle motion (displacement, velocity, acceleration) waveforms, not all of the seismological tools developed over the past century (e.g., magnitude estimation, seismic beamforming, etc.) can be readily applied to strain data. Notably, the directional sensitivity of DAS differs from conventional particle motion sensors, and DAS experiences an increased sensitivity to slow waves, often composed of highly scattered waves that are challenging to analyze. To address these issues, several strategies have been already proposed to convert strain rate measurements to particle velocity.Based on a previously proposed mathematical formalism, we stress some fundamental differences between path-integrated strain and conventional displacement measurements. DAS inherently records arc length variation of the cable which is a relative motion measurement along a curvilinear path. We show that if the geometry of the DAS deployment is adapted to the wavefield of interest, path-integrated strain can be used to closely approximate the displacement wavefield without the need of additional instruments. We validate this theoretical result using collocated seismometers, discuss the limitations of this approach, and show two benefits: enhancing direct P-wave arrivals and simplifying the magnitude estimation of seismic events. While using path integrated strain is in some aspects more challenging, it achieves flat (hence lower) noise levels both in frequency and wavenumber. It also provides better sensitivity to high velocity phases, and permits the direct application of conventional seismological tools that are less effective when applied to the original strain data.
Multidisciplinary approach to the study of a crustal tectonic discontinuity: an example from the Central Mediterranean offshore (Sicily channel)
Authors: Bongiovanni Simona , Maiorana Mariagiada , D'Alessandro Antonino , Martorana Raffaele , Sulli Attilio
Published: February 2023

The central Mediterranean is a geodynamically very complex area included in the convergence zone between the European plate and the African plate. We investigated the western sector of the Sicily Channel , which shows, according to literature data, different deep and shallow tectonic structures than the eastern sector.  Structural data show the presence of a crustal-scale discontinuity that has generated major seismic events such as the Belice earthquake of 1968. This structure has been identified as a wideband roughly oriented N-S from the San Vito Lo Capo to the Sciacca area (SVCS band, San Vito Lo Capo - Sciacca band) (Di Stefano et al., 2015) and continuing offshore to the Pantelleria area. In this work, through multidisciplinary data analysis, we aim to investigate the correlation between the surface structures highlighted onshore and the offshore continuation. For this purpose, we considered offshore data from the Sicily Channel including: gravimetric data, which show negative anomalies in the Pantelleria graben (Palano et al., 2020) and in the Sciacca offshore and velocity models showing the lateral variation of the Moho with values ranging from 30 to 33 km depth and values ranging from 20 to 23 km depth respectively west and est of the Pantelleria graben (Finetti, 2005). These data were compared with our interpretation of crustal reflection seismic profiles and seismic events (since 2005 with M≥2). The results show an alignment of seismic events with roughly N-S direction from offshore Sciacca to Lampedusa. Moreover, the seismic profiles show a lateral variation of the Moho depth deepening estward. From the joint analysis of these data we obtained a geological model of the investigated sector defining the offshore prosecution of the SVCS band present onshore. The present work may be useful for understanding the geodynamic evolution and for studying the seismic hazard of this area. ReferencesDi Stefano P., Favara R., Luzio D., Renda P., Cacciatore M. S., Calò M., Napoli G., Parisi L., Todaro S., Zarcone G. (2015). A regional-scale discontinuity in western Sicily revealed by a multidisciplinary approach: A new piece for understanding the geodynamic puzzle of the southern Mediterranean, Tectonics, 34, 2067–2085, doi:10.1002/2014TC003759.Finetti I. R. (Ed.). (2005). CROP project: deep seismic exploration of the central Mediterranean and Italy. Elsevier.Palano M., Ursino A., Spampinato S., Sparacino F., Polonia A., Gasperini L. (2020). Crustal deformation, active tectonics and seismic potential in the Sicily Channel (Central Mediterranean), along the Nubia–Eurasia plate boundary. Scientific reports, 10(1), 1-14.
Modelling gravitational convection and miscible flows in heterogeneous porous media with a semi-Eulerian-Lagrangian scheme: implications for deep carbon sequestration.
Authors: Sen Sayan , Hansen Scott
Published: February 2023

The non-linear interaction of supercritical CO2 with brine in confined saline aquifers is an important problem in geophysical fluid dynamics and understanding its mechanism is pivotal for the design of carbon-sequestration schemes. In principle, dissolution of CO2 into the ambient brine from a buoyant supercritical phase across the CO2-brine interphase causes the density of the mixed diffusive layer to increase, thereby triggering gravitational instability generating Rayleigh-Taylor like convection and increasing CO2 dissolution and uptake by the reservoir. These dynamics are nonlinear and must be studied numerically, with previous works commonly focusing on homogeneous domains and pure diffusion only and often assuming no background flow in the aquifer.
We discuss a large-scale numerical Monte Carlo study considering the three-way interaction of heterogeneous permeability and porosity field structure, background flow, and local-scale dispersion on CO2 uptake. For this purpose, we developed a novel combined Eulerian flow—Lagrangian transport code for simulating single-phase CO2-enriched brine movement in systems featuring a spatially varying density field controlled by dissolved CO2 concentration and a background pressure gradient. The usage of the Lagrangian approach uniquely allows us to quantify the effect of local-scale horizontal and longitudinal dispersion on the flow dynamics and capture relevant non-Fickian transport behaviors without the confounding effect of numerical dispersion and to maintain numerical stability under strongly advective conditions.
We present results characterizing the impact permeability-porosity structure, background flow, local dispersion on CO2 uptake and fingering dynamics. Quantifying these factors via appropriate dimensionless groups, we analyze their impact on onset time of convection, and on regime transition from gravitationally dominated convection to background flow dominated advection-macrodispersion regimes. The relationship between porosity-permeability structure and fingering dynamics is also outlined and quantified.
An Adimensional Ice-Sheet-Climate Model for glacial cycles
Authors: Pérez-Montero Sergio , Alvarez-Solas Jorge , Robinson Alexander , Montoya Marisa
Published: February 2023

Although the ultimate trigger of glacial cycles is Milankovitch insolation cycles, there are still uncertainties concerning their timing and transitions. These unknowns are believed to be due to intrinsic nonlinearities in the climate system, and there is a deep interest in their solution. However, the longer timescales involved make it infeasible to use comprehensive climate models because of the large computational cost involved. In this context, conceptual models are built to mimic complex processes in a simpler, computationally efficient way. Here we present an adimensional ice-sheet–climate model (AMOD), which aims to study these outstanding paleoclimatic topics. AMOD represents ice sheet dynamics by using common assumptions as in state-of-the-art ice-sheet models, adapted to its dimensionless nature, and it solves surface mass balance processes and the aging of snow and ice. In this way, AMOD is able to run several glacial cycles in seconds and produces results comparable to those of paleoclimatic proxies. Preliminary results indicate nonlinearities related to both ice dynamics and snow aging that determine the timing and shape of deglaciations.
Spring-neap tidal cycles are major drivers for biogeochemical variability in two large outer estuaries
Authors: Macovei Vlad , Rewrie Louise , Voynova Yoana
Published: February 2023

The land-ocean continuum is a key component of the biogeochemical cycling of carbon and nutrients. At the same time, the rapidly changing conditions at the river-sea interface make the nearshore regions highly dynamic and variable. For better understanding of the drivers of this variability, high temporal and spatial frequency observations are needed. Here, we use ship-of-opportunity measurements in the outer estuaries of the Humber (UK) and Elbe (Germany) rivers to show that essential ocean variables in these regions vary with a periodicity that matches the spring-neap tidal cycles. The tidal disturbance was observed up to 10 km offshore from the river mouth. While at neap tide, the conditions at this location were typical of the open North Sea, during spring tide, the salinity dropped below 15, the turbidity was high (>50 FTU), dissolved oxygen dropped to under-saturated values and the partial pressure of carbon dioxide (pCO2) in seawater rose above 700 µatm. Since neap tide seawater pCO2 values were below 400 µatm, lower than atmospheric levels, the near-shore area shifts between being a sink and a source of carbon dioxide to the atmosphere on roughly one-week timescales. This behaviour is currently not resolved in some biogeochemical models. Correctly integrating the drivers of this variability into regional assessments is essential for the accurate evaluation of shelf sea carbon budgets.
Composition of extracellular polymeric substances (EPS) produced by a range of soil bacteria and fungi
Authors: Leme Oliva Rebeca , Bahadur Khadka Umesh , Dyckmans Jens , Redmile-Gordon Marc , Georg Jörgensen Rainer
Published: February 2023

Microorganisms are known to form a matrix of extracellular polymeric substances (EPS) on several solid surfaces such as soils. The formation of this matrix provides various benefits not only to the microbial community, but also to the surface it is attached. In soils, for instance, it promotes protection and adherence of microorganisms to soil aggregates and benefits the soil increasing aggregate stability. Even in spite of this knowledge, the contribution of EPS to soil organic matter (SOM) and to SOM turnover is yet unclear, mainly due to methodological limitations. Furthermore, it has also not been determined how the EPS composition affects soil structure, fertility and organic matter dynamics. It is therefore of uttermost importance to study the composition of the EPS matrix and how different microbial functional groups produce EPS in face of varying environmental conditions. To this end, 10 bacterial and 10 fungal species commonly found in soils were grown under different treatments in order to stimulate EPS production. Microorganisms were grown in either glycerol or starch medium with or without the presence of sterile quartz. EPS was extracted using a cation-exchange resin (CER) and its composition was subsequently determined with the quantification of proteins, carbohydrates, amino sugars and DNA. We hypothesized firstly, that EPS production would be higher in cultures with quartz. Secondly, we also expected bacterial EPS production to be higher in cultures with glycerol whereas fungal cultures would produce more EPS in starch medium, reflecting contrasting substrate effects on bacterial and fungal EPS formation. Lastly, we hypothesized that considerable amounts of galactosamine would be found in all extracted EPS, similarly to mucins excreted in the intestines of vertebrates, protecting enzymes. Mucins are a family of proteins with high GalN contents, consequently, GalN might be an indicator to EPS production in soils.
A feasibility study for a novel remediation and sustainable growth digital tool for the Environment Agency, England, UK
Authors: Beriro Darren , Macklin Yolande , Thrasher Jane , Griggs David , Haslam Angela
Published: February 2023

The remediation of brownfield is vital to sustainable place-making and levelling up across the country. It provides an improved local environment that can unlock regeneration and the social, economic and ecological revitalisation of communities. However the total benefits of remediation are not fully understood or utilised in decision making. As a result, sites can remain derelict for years and opportunities to optimise value from public and private investment are missed.Jacobs and BGS undertook research for the Environment Agency in England to evaluate the feasibility of developing a tool, which included:A virtual workshop using MURAL to enable digital interaction and collaboration to refine scope, define data requirements and map project stakeholders;
Primary benefit and user requirements research, including looking at the potential impact of a tool through the development of a Theory of Change model and focussed interviews with key stakeholders to understand user requirements.
Review of academic and grey literature;
Accelerated design sprint to frame the problem/opportunity, explore technology agonistic solutions for the tool and develop into a storyboard.
Develop a low fidelity prototype as a blueprint of how a tool might look.
The outcome of the work indicated there is both a need and demand for such a tool. It was also demonstrated to be technically feasible through the literature review and design sprint. Such a tool would have an extremely positive impact on the perceptions of brownfield, shifting it from a constraint to an opportunity. The presentation will provide a summary of the methods, an overview of the results and a demonstration of a prototype digital tool. Our disucssion will focus on the opportunities presented by using systems thinking combined with design thinking to influence the approach taken to planning and redeveloping brownfield sites.  
Frequentist rainfall thresholds for landslide forecasting in the Darjeeling and Nilgiris districts in India
Authors: Melillo Massimo , Gariano Stefano Luigi , Brunetti Maria Teresa , Rossi Mauro , Kumar Sumit , Mathiyalagan Rajkumar , Peruccacci Silvia
Published: February 2023

India is heavily affected by rainfall-induced landslides that cause fatalities and damage. Therefore, the development of effective and reliable models for the landslide forecasting and their possible integration in early warning systems (LEWSs) is necessary to mitigate the risk posed by such phenomena. Within the LANDSLIP (LANDSLIde Multi-Hazard Risk Assessment, Preparedness and Early Warning in South Asia: Integrating Meteorology, Landscape and Society; www.landslip.org) project, we developed threshold-based forecasting models to predict the occurrence of rainfall-induced landslides. The models were calibrated  in two Indian pilot areas: the Darjeeling and Nilgiris districts, in the states of West Bengal and Tamil Nadu, respectively. For the purpose, we built  two catalogs of 84 and 116 rainfall conditions likely responsible for landslide triggering in Darjeeling and Nilgiris, respectively, and daily rainfall measurements, which were used to define frequentist rainfall thresholds at different non-exceedance probabilities by means of an automatic tool (CTRL-T). A revision of the methodology to identify the rainfall conditions that triggered the failures was necessary due to possible inaccuracies in the landslide occurrence date and the daily temporal resolution of rainfall measurements in India. Triggering rainfall conditions were also related to the different monsoon regimes in the study areas. For a few uncertain events, the rainfall conditions automatically reconstructed by CTRL-T were revised after a consensus among several investigators. In agreement with the rainfall regimes of the two pilot areas, the thresholds for Darjeeling are higher than those for Nilgiris; regardless of the rainfall duration, a larger amount of rainfall is necessary to trigger landslides in the Darjeeling area. Despite some limitations, mostly due to the daily temporal resolution of rainfall data and the spatial and temporal distribution of the reported landslides, the uncertainties of the calculated thresholds were acceptable (also thanks to the double checking) to allow their implementation in the LANDSLIP prototype LEWS. The thresholds require ongoing evaluation and refinement. For the purpose, additional landslide and rainfall data were used to validate thresholds and improve forecasts.
Investigation of weather conditions and BrO during ozone depletion events between 2010 and 2021 in Ny-Ålesund
Authors: Zilker Bianca , Richter Andreas , Blechschmidt Anne-Marlene , Bougoudis Ilias , Seo Sora , von der Gathen Peter , Bösch Tim , Burrows John P.
Published: February 2023

Ozone Depletion Events (ODEs) have been observed since the late 1990s in the polar regions during spring, often in combination with Bromine Explosion Events (BEEs). In a heterogeneous, autocatalytic, chemical chain reaction cycle, inorganic bromine is released from the cryosphere into the troposphere and depletes ozone, sometimes to below detection limit. Besides low temperatures favoring the bromine explosion reactions, two different meteorological conditions are mainly observed during these events: on the one hand, low wind speeds and a stable boundary layer, where bromine can accumulate and deplete ozone, and on the other hand, high wind speeds above approximately 10 m/s with blowing snow and a higher, unstable boundary layer. The second condition often occurs in combination with polar cyclones, where bromine can be recycled aloft on snow and aerosol surfaces.In this study, two long term ozone data sets, one from ozone sondes launched in Ny-Ålesund and the other from in-situ measurements on Zeppelin mountain – located close to Ny-Ålesund – have been evaluated from March until May between 2010 and 2021 to detect ODEs. To analyze the prevailing weather conditions during these events, ERA5 reanalysis data has been used and separated between weather conditions during ODEs and no-ODEs based on the respective ozone data set. The evaluation of the two data sets led to very consistent results: during ODEs, lower pressure is observed east of Svalbard and higher pressure over Greenland, leading to a transport of cold polar air from the north to Ny-Ålesund. Also higher wind speed and a higher boundary layer are noticed, supporting the assumption, that ODEs often occur in combination with polar cyclones.Using the same approach, the long-term tropospheric BrO data set from Bougoudis et al., 2020 in combination with S5P TROPOMI retrievals of tropospheric BrO has been used to analyze BrO patterns. During ODEs in Ny-Ålesund, the satellite data show elevated values all over the Arctic, but especially north of Svalbard. This work was supported by the DFG funded Transregio-project TR 172 “Arctic Amplification (AC)³“ in subproject C03.
Evolution of warm water intrusions in the Filchner Trough, Antarctica
Authors: Teske Vanessa , Timmermann Ralph , Semmler Tido
Published: February 2023

The Filchner Trough on the continental shelf in the southern Weddell Sea is a region of great importance for the water mass exchange between the open ocean and the Filchner Ronne Ice Shelf cavity. Observations of the last 20 years and modelling studies show seasonal variations and longer lasting pulses of warm water intruding into the trough and reaching the Filchner Ice Shelf front. In this study, we evaluate the evolution of these intrusions in four climate scenarios defined for CMIP6 and simulated with the AWI Climate Model. We show that a warming climate will lead to more frequent pulses in the mitigation scenarios SSP1-2.6 and SSP2-4.5. For the high emission scenarios SSP3-7.0 and SSP5-8.5, hydrography in Filchner Trough will shift to a substantially warmer state during the second half of the 21st century with a temperature rise of 2°C in the trough until 2100. We demonstrate that the system‘s tipping into a warmer state is primarily caused by changes in the local sea ice formation and the depth of the Antarctic Slope Front. Our results show that a regime shift can be avoided by reaching the 2°C climate goal.
Assessment of Land Subsidence based on Geological Conditions, Groundwater Levels in the Choshui River Alluvial Fan, Taiwan
Authors: Su Shang-Hsuan , Yu Hwa-Lung
Published: February 2023

        Due to climate change, Taiwan's rainfall has become unstable in recent years, leading to short rainy seasons and low rainfall. In 2021, a severe drought occurred due to the lowest rainfall on record. Groundwater is essential for agricultural development, but less than 10% of wells are legal. Improper or excessive use of groundwater resources can cause serious disasters, such as sea intrusion and land subsidence. However, if the government and farmers extract groundwater effectively and sustainably, it will bring more flexibility to water management.        In this study, a land subsidence model was conducted based on geological conditions and groundwater level. This study analyzes multi layer compaction monitoring well profiles, and further finds the correlation among the two main factors and subsidence. The goal of this study is to visualize which areas are more suitable for using groundwater and assist the government in water resource management. This study focuses on the Choshui river alluvial fan in Taiwan. A risk map of land subsidence for this area is made by evaluating two main factors, geological conditions and groundwater level.
Glide-snow avalanches: insights from combining field monitoring, time-lapse photography and SNOWPACK simulations
Authors: Fees Amelie , van Herwijnen Alec , Lombardo Michael , Schweizer Jürg
Published: February 2023

Glide-snow avalanches release due to a loss of friction at the snow-soil interface, which can result in large avalanches that endanger infrastructure in alpine regions. It is hypothesized that glide-snow avalanche release is linked to the presence of liquid water at the snow-soil interface, but the driving physical processes are poorly understood and prediction remains difficult. To better understand these driving physical processes, we monitored soil (water content, matric potential, temperature) and snow properties (water content, temperature, weekly snow profiles) across a small slope (40 m x 70 m) at the Dorfberg field site above Davos, Switzerland for the winter seasons 2021/22 and 2022/23. These observations were supplemented with SNOWPACK simulations for 10 release zones across Dorfberg. In addition, SNOWPACK simulations were used to supplement a dataset of more than 900 glide-snow avalanches that were previously (seasons 2009-2023) recorded on Dorfberg using time-lapse photography. Analyses of both SNOWPACK and monitoring data show high spatial variability of soil and snow properties across the monitored slope and across Dorfberg. Spatial variability in soil water content across the monitoring slope was higher during early winter than during spring when melt-freeze cycles and subsequent water infiltration in the soil cause a spatial homogenization. Transferring findings from the field monitoring to the large dataset allowed for the identification of several temporal patterns. For example, we see a positive correlation between mean snowpack density and the number of melt-freeze cycles prior to avalanche release in spring. We see a similar correlation with snow height. Overall, our measurements show that on Dorfberg several diurnal melt-freeze cycles are necessary before glide-snow avalanche release in spring.