bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical investigation of offshore freshened groundwater reservoirs in the East China Sea
Authors: Thomas Ariel , Duan Shuangmin , Zou Zhihui , Micallef Aaron
Published: February 2023

Offshore freshened groundwater (OFG) has been proven to exist in continental margins around the world and has been identified as a potential unconventional water resource. In China, freshwater resources are very limited in the developed coastal areas and islands. Buried paleo-channels associated with the ancient Changjiang (Yangtze) river are suspected to be viable hosts of a offshore freshened groundwater reservoir system in the East China Sea, North of Chengsi island. In this study, we used an integrated modeling approach to predict OFG potential and optimize the design of a controlled source electromagnetic survey to image the reservoir. We develop a conceptual 2D geological model of the Quarternary sediments in the region. Porosity and permeability values were assigned based on borehole observations to produce a hydrogeological model. We present the results of a numerical modeling study of groundwater transport and variable density flow as a result of sea-level fluctuation over the past 200,000 years. Based on the bathymetry, the present-day shelf was sub-aerially exposed to meteoric recharge for most of that period. We considered a range of recharge scenarios and the simulation results indicate a high likelihood that freshwater reservoirs would be preserved until present day. Two freshwater intervals were observed between 80 m – 100 m, and 200 m – 300 m below the seafloor. A layered resistivity model was designed based on the observation of two primary freshwater reservoir layers in the flow model. Numerical tests were carried out on the feasibility of controlled- source electromagnetic method in the study area to optimize the survey setup. This approach can be adapted for offshore freshened groundwater prospecting in other siliciclastic shelf environments.
Prediction of Pb and Zn in urban soil using VIS-NIR-SWIR spectroscopy
Authors: Nakhostinrouhi Mahsa , Saberioon Mohammadmehdi , Makki Mohsen , Thestorf Kolja , Homayouni Saeid , Kiavarz Majid , Alavipanah Seyed Kazem
Published: February 2023

Heavy metals serve as a subset of chemical elements with higher density than iron. Besides, these environmental pollutants are constant and nonbiodegradable elements that can cause toxicity and genetic mutations to the live cells. Depending on the study area, an increase in soil heavy metals from a specific level often created by human activities can lead to many adverse effects on individuals, soil, and plants. In case of their existence in the food chain or transfer to groundwater resources, human health is seriously threatened. Over numerous years, being affected by a colossal number of pollutant resources such as world war and household waste, industry, transportation systems, and urbanization has changed Berlin to a city at risk of soil pollution by heavy metals. That is why carrying out a study on heavy metals in this city is of great significance. Chemical analysis is the first and most traditional ways to measure soil heavy metals. Despite high precision, this method is complicated, time-consuming, costly, and ineffective on a large scale. However, the spectral data facilitates the rapid and cost-effective assessment of these elements. Therefore, in this study, the ability of spectral data to predict heavy metals in Berlin’s soil is examined.When it comes to the data required, there are two categories: 1) heavy metals (Pb and Zn) related to more than 600 soil samples collected from 2016 to 2018 and measured in the laboratory, and 2) the spectral data measured for each sample in the range between 350 to 2500nm in a spectrometry lab. All data is divided into training (80%) and testing (20%) to reach this aim. Next, the first group is used to train the machine learning algorithms, including partial least square regression (PLSR), support vector regression (SVR), and random forest (RF). Moreover, the second group is used to test the models. Finally, the accuracy of models is evaluated by correlation of determination (R2), and Root mean square error (MSE). As a part of the results, R2 and MSE were achieved 0.25, and 4394.45 for Pb, and 0.18 and 6558.49 for Zn.
An analysis of the European space weather modelling capabilities
Authors: Amaya Jorge
Published: February 2023

For many years the Space Weather Office of the European Space Agency has promoted the development of resources for the monitoring of solar activity and its effects on our planet and technology. Current and past activities include the gathering and distribution of data from ground and space observatories, the deployment of specialized instruments onboard hosting satellites, the proposal of new nanosat missions, the promotion of improvements in computer models, and the design of Vigil, the first operational space weather mission in Europe. Multiple international institutions have also developed their own space weather assets. However, in contrast to meteorological forecasts, no prediction centre is still capable to produce accurate forecasts of the space weather conditions in the next days. Private and public institutions around the world are working on the improvement of forecasting tools. For ESA this effort requires additional support on the development of critical modelling techniques, including: data assimilation, uncertainty quantification, ensemble forecasting, machine learning, and model coupling, among others.

 

To have a clear mapping between the existing modelling capabilities in Europe and the user requirements, we invited European experts to participate in the "Space Weather Modelling Workshop" held in March 2023 at ESOC. In this presentation we will show the results of this workshop, including a detailed summary of the European modelling capabilities, a description of the existing gaps and overlaps, an analysis of missing assets, a description of existing bottlenecks, and a plan to improve the accuracy of space weather forecasting. The ESA Space Weather Office has set goals for the next years in the area of modelling, based on the data collected during the workshop, on discussions with the community, and on data from the literature. We will describe how the community can contribute to reach these goals and to develop the new generation of European Space Weather forecasting services.
New insights on the ultramafic intrusions surrounding the Kunene Anorthosite Complex (SW Angola) from gravity, magnetic and radiometric data
Authors: Represas Patrícia , Sousa Pedro , Morais Igor , Cordeiro Domingos , Carvalho João , Batista Maria João , Dito Manuel , Llorente José Maria , Marques Fábio , Mateus Teodora , Rodrigues José Feliciano , Lobón José Luis , Oliveira Daniel
Published: February 2023

The Kunene Anorthosite Complex (KAC), located in SW Angola, is one of the largest anorthosite structures in the world. Dating from the Mesoproterozoic, its installation process is still not clear. Several mafic and ultramafic outcrops can be found surrounding the KAC. Once considered related with its emplacement, the study of these bodies may help us understand the history of this unique geological feature. While geochronological data show that they are synchronous, or possibly a bit younger, than the embedding granites and migmatites of Paleoproterozoic age, the question arises of whether they are intrusions installed in the host rock or if they are instead recycled remains of older Arch crust. The development of these outcrops in depth provides relevant clues regarding the origin of these bodies and their relationship with the Eburnean (~1.93-2.04 Ga) and Epupa-Namibe (~1.83-1.74 Ga) events. One of these mafic outcrops, designated the Hamutenha outcrop (Huíla Province) exhibits an elongated shape and a NW-SE orientation and is characterized by an internal zonation.  Generally, the innermost part is composed of ultramafic rocks of (mostly harzburgites and dunites), with diorites outcropping in its NW and SE borders. The Hamutenha outcrop was previously identified for potentially bearing Cr, Ni and PGE mineralization.Therefore, the aim of this study is two-fold. Firstly, it attempts to determine the development at depth of the mafic body to better understand its origin. Secondly, it tries to clarify the emplacement mechanisms responsible for the potential mineralization and to evaluate the likelihood of its economic potential. Aeromagnetic and ground gravimetric data acquired in the framework of project PLANAGEO (National Geology Plan for Angola) of which the National Laboratory of Energy and Geology (Portugal) was one of the partners, was used to create a magnetic vector model and a density contrast model of the Hamutenha body. These 3D models were interpreted in combination with the detailed geological observations and aeroradiometric data also from the PLANAGEO project, providing new insights on the underground lithological differentiation and geometry of this geological structure.
Using a holistic modelling approach to assess drivers of hydrological change and the impact of irrigation in a water/data scarce environment
Authors: Watson Andrew , Kunne Annika , Miller Jodie , Kralisch Sven
Published: February 2023

This study examines the impact of irrigation and precipitation variability on the hydrological system of the Verlorenvlei estuarine lake, a sensitive RAMSAR-listed ecosystem located north of Cape Town, South Africa. The study uses a holistic modelling approach, including the JAMS/J2000 rainfall-runoff model, to evaluate the impact of water abstraction, losses during storage, and field application as irrigation on the lake's streamflow. The model was able to achieve a satisfactory calibration for the period 1989-1993, but uncertainties remain in the model simulated processes due to data availability. The study found that irrigation in the area has reduced total simulated streamflow by 7% to 16%, and that a significant amount of water is lost from the dam surface due to evaporation. The study also found that measured precipitation was highly variable (-29% to +2%) and reduced/increased simulated streamflow by -76% to +67% during the evaluation period. The results of this study highlight the impact that irrigation has on water resources and the need to consider its effect on ecosystem and food production losses. The study suggests that lower evaporation losses from dams is a potential adaptation option to reduce the impacts of hydrological change in the region, and it emphasizes the importance of appropriate management strategies to ensure sustainable agricultural supply chains in water-scarce areas.
The impact of climate extremes on vegetable production in Eswatini
Authors: Sun Xun , Stuivenberg Aswin , Willy Daniel , Tarus David , Okogbenin Emmanuel , Wouterse Fleur
Published: February 2023

Climate change is manifested both through gradual shifts away from stable climatic circumstances and through climate-related extreme events. Climate change already affects human and natural systems and has put global food production at risk. African countries, most of which have agriculture-based economies, face significant challenges. Due to the lack of historical observation data in many countries on the continent, it is difficult to quantify the impact of climate change on agricultural production. Most of these "historical data" exist in people's memory. Therefore, having comprehensive survey data is of great importance for understanding the role of climate change. The Global Center on Adaptation (GCA) and the African Agriculture Technology Foundation (AATF) conducted joint research in Eswatini to study the impact of climate change on the vegetable sector. The researchers surveyed 370 farm households in four project areas. The survey contained a hundred questions in ten sections including family background, the agricultural production process, farming equipment, climate risk and adaptation strategies and digitalization. We analyze these data with statistical models to assess the impact of climate change on Eswatini's vegetable production and the potential for climate risk mitigation through adaptive production strategies.
Benchmarking CMIP6 Earth System Models using MESMER-M climate emulator trained on observational data
Authors: Pelser Tristan , Nath Shruti , Lejeune Quentin , Beusch Lea , Gudmundsson Lukas , Seneviratne Sonia I. , Schleussner Carl F.
Published: February 2023

The latest ensemble of climate models (CMIP6) displays greater overall uncertainty than the previous iteration, with a larger spread of temperature projections by the end of the 21st century. Given that these model projections are essential towards policy and decision making, accurately quantifying their biases and uncertainties (model benchmarking) is an important process towards building public trust. Climate model emulators are able to explore the uncertainty phase space surrounding climate model projections at a fraction of the computational cost and present themselves as valuable tools for climate model benchmarking. In this study, we extend the benchmarking approach using the MESMER climate model emulator (Beusch et al. 2020) from evaluating annual to evaluating monthly performances of climate models, by employing MESMER’s monthly downscaling module, MESMER-M. For consistent comparison with climate model initial-condition ensembles, we first characterise the uncertainty due to natural climate variability surrounding observed regional climate change. To do so, we develop an observationally-consistent emulator by calibrating MESMER-M on BEST observational data. The emulator’s capacity to capture the observed Global Mean Temperature (GMT)-induced local, monthly temperature responses and their surrounding variability is then demonstrated by considering their linear scaling relationships. We find that the observationally-consistent emulator performs better in January than July, and performs worst over regions with strong natural variability, a high ratio of water to land, or low data availability. In addition to significant variations in model skill, we find that almost all models over-predict the amplitude of the seasonal cycle. Following this, we benchmark a set of 21 CMIP6 models against the observationally-consistent, emulated temperature trends. Compared to Beusch et al. (2020), we also find that annual skill does not necessarily translate to monthly skill for the models. Thus, MESMER-M can be calibrated on a single realisation of observational data to produce acceptable results for later use in benchmarking climate models.

 

 

Beusch, L., Gudmundsson, L., & Seneviratne, S. I. (2020). Crossbreeding CMIP6 Earth System Models With an Emulator for Regionally Optimized Land Temperature Projections. Geophysical Research Letters, 47(15). https://doi.org/10.1029/2019GL086812

 
Mapping and assessing the spatial extent of floods using Sentinel 1 SAR Data – An approach based on Flood Index Estimation
Authors: Devaraj Suresh , Kasiapillai Sudalaimuthu Kasiviswanathan , Budamala Venkatesh , Pattabiraman Balasundaram , Ahamed Kalel
Published: February 2023

Water alone accounts for more than 70% of global fatalities, mainly the floods and droughts, among other natural disasters. In a highly populated country like India, accurate rapid flood mapping plays a vital role in disaster response activities. Brahmaputra is one of the perennial rivers in India that experiences frequent floods, and the present study aims at developing a flood index for the identification of the flooded regions using Sentinel 1 SAR datasets over middle Brahmaputra River basin. Images acquired before and during the flood will be used to develop the flood index. Flood extent identified using the index will be used to classify the vulnerable zones, that can be utilized by the concerned government authorities for various mitigation and management purposes.
Glider Survey reveals the evolution of the mesoscale and submesoscale structures in the Balearic Sea: Formation, Intensification, and Decay.
Authors: Zarokanellos Nikolaos , Rudnick Daniel , Mourre Baptiste , Garcia-Jove Maximo , Lermusiaux Pierre , Tintoré Joaquín
Published: February 2023

Mesoscale features and their corresponding submesoscale structures may generate a substantial vertical transport of carbon and biogeochemical tracers from the surface to the interior. The baroclinic instabilities formed from the Northern and Balearic Currents are associated with vigorous mesoscale eddy activity in the Balearic Sea. In the CALYPSO 2022 experiment, eight gliders were programmed to dive as deep as 700 m from 25 March until 21 June 2022. The glider fleet measured temperature, salinity, velocity, chlorophyll fluorescence, oxygen, and acoustic backscatter. The glider data was mapped utilizing objective mapping of the across-front, along-front, and time on 10 m vertical levels. The geostrophic velocity was inferred using a variational approach. We estimate the vertical and ageostrophic horizontal velocities using the omega equation. The glider observations provide a complete description of the evolution of the eddy field. The analysis of the uplifted isopycnal surface as the eddy formed showed consistency between the movement of the dynamic and biogeochemical tracers. Glider data show the evolution of a cyclonic eddy (20-30 km) in the area, where vertical velocities tend to be downward. As the eddy developed, its axis shifted westward. The isopycnal uplift inside the pycnocline can provide nutrients to the euphotic zone. While the initial cyclonic feature has dissipated, a second shoaling of the 28.9 isopycnal occurred in the east toward the end of April 2022, where the biggest relative vorticity (~0.5 ζ/f) was observed in the region. The eddy extended during its growing phase, showing a westward shift of the eddy axis. The observed peak downward vertical velocities were near 30 m day-1 during the eddy intensification, with the size of the cyclonic eddy varying between 20-30 km. The new cyclonic feature has been spreading in the area for a few days before dividing into two separate cyclonic eddies (15km) around the beginning of May. The two smaller cyclonic eddies moved north and west until they vanished from our study area. However, an anticyclonic structure (20km) was developed within their separation. The vertical velocity tended to be downward on the dense side of the front and upward on the light side, flattening the eddy characteristic. The glider observations reveal horizontal density gradients up to 0.5 kg m-3 over ~10 km. The obtained maximum velocities were up to 30 cm/s in the region. Upwelling and downwelling were also detected by chlorophyll fluorescence, oxygen, and acoustic backscatter near the frontal interface. Glider observations were integrated with remote sensing and modeling simulations to evaluate mesoscale and submesoscale variability in developing vertical velocities in the Balearic Sea and their impact on biological carbon storage. 
Do Mesoscale Convective Systems precipitation follows the Clausius-Clapeyron relationship?
Authors: Da Silva Nicolas , Haerter Jan
Published: February 2023

Floods related to heavy precipitation are common over Europe during both the warm and the cold seasons. In a way to better understand these heavy precipitation systems and their potential evolution in a warming climate, several studies investigated the dependency of precipitation extremes to temperature over Europe (e.g. Lenderink et al., 2008; Berg et al., 2013). It was found that the scaling of precipitation extremes can exceed the scaling expected from the Clausius-Clapeyron (CC) relationship, relating temperature to the water holding capacity of the atmosphere. While several potential explanations were proposed, a recent study (Lochbihler et al., 2017) noted the important role of large systems in determining this “super-CC” scaling over the Netherlands.
Building on this study, we further investigate the role of Mesoscale Convective Systems (MCS) in determining the temperature precipitation relationship over Europe. The detection and tracking of MCSs is based on the recent Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (IMERG; Huffman et al., 2019) satellite precipitation climatology. We use the EUropean Cooperation for LIghtning Detection (EUCLID) lightning dataset to distinguish between stratiform (or shallow convective) and deep convective rain patches without introducing bias in precipitation intensity. We select the temperature upstream of the MCS tracks, as a proxy of the moisture source involved in the formation of MCS precipitation.
MCS can display strong dynamical features such as the rear inflow jet or cold pools, of which the effects on precipitation as well as their changes with temperature are still unclear. It suggests that MCS precipitation may deviate significantly from the CC scaling. Additionally, the processes involved in MCS precipitation may differ depending on the stage of the MCS life cycle. We thus characterize the temperature dependency of MCS precipitation and their 2-D structure at different stages of their life cycle. This work contributes to better understanding the drivers of MCS precipitation and how these may evolve in a warming climate.
References
Berg, P., Moseley, C., & Haerter, J. O. (2013). Strong increase in convective precipitation in response to higher temperatures. Nature Geoscience, 6(3), 181-185.
Huffman GJ, Stocker EF, Bolvin DT, Nelkin EJ, Tan J. 2019. GPM IMERG final precipitation L3 half hourly 0.1 degree x 0.1 degree V06, Greenbelt, MD, Goddard Earth Sciences Data and Information Services Center. doi: 10.5067/GPM/IMERG/3B-HH/06
Lenderink, G., & Van Meijgaard, E. (2008). Increase in hourly precipitation extremes beyond expectations from temperature changes. Nature Geoscience, 1(8), 511-514.
Lochbihler, K., Lenderink, G., & Siebesma, A. P. (2017). The spatial extent of rainfall events and its relation to precipitation scaling. Geophysical Research Letters, 44(16), 8629-8636.
Large-Scale Climatic Drivers of Flood Frequency across Sub-Saharan Africa
Authors: Ekolu Job , Dieppois Bastien , Eden Jonathan , Tramblay Yves , Villarini Gabriele , Moulds Simon , Slater Louise , Mahé Gil , Paturel Jean-Emmanuel , Sidibe Moussa , Camberlin Pierre , Pohl Benjamin , van de Wiel Marco
Published: February 2023

Sub-Saharan Africa is affected by a high level of temporal and spatial climate variability, with large impacts on water resources, human lives, and economies, notably through hydrological extremes such as floods. Nevertheless, the key climatic factors driving interannual variability in flood frequency remain poorly documented and understood. To address this research gap, we first compile information on large-scale climate drivers that may potential affect sub-Saharan African hydroclimate (e.g., El Niño–Southern Oscillation, Atlantic Multidecadal Variability). Then, using a new 65-year long daily streamflow dataset of over 600 stations in sub-Saharan Africa, a bootstrapped stepwise regression and relative importance analysis is applied to quantify the relative contribution of different ocean basins to interannual variability in flood frequency between 1950 and 2014. Results show that interannual variations in the frequency of flood events are significantly linked to different modes of climate variability in the Pacific, Indian, and Atlantic Oceans. These modes of climate variability together explain around 60% of observed interannual variation in seasonal flood frequency. The relative influence of each ocean basin, however, differs from one region to another. The Indian and Pacific Oceans, for instance, have significant influences on interannual variations in the frequency of floods between December and May across much of southern and eastern Africa. In western Africa, the Mediterranean and Atlantic Oceans appear to have a dominant influence between September and November. In central Africa, the relative influence of different oceans basins is seasonally variable. Using the best combination of Sea-Surface Temperature predictors, we then examine projected future trends using a large ensemble of climate models from the CMIP6 experiments.
Contrasting levels of surprise and levee effect between municipalities in the 2021 flood in Belgium
Authors: Rodriguez Castro Daniela , Roucour Solène , Archambeau Pierre , Dessers Christophe , Erpicum Sébastian , Pirotton Michel , Cools Mario , Teller Jacques , Dewals Benjamin
Published: February 2023

In July 2021, the Bernd low-pressure system induced disastrous floods over part of Germany, the Netherlands and Belgium. Relatively small catchments were mostly affected. In Belgium, nine out of the ten most impacted municipalities are situated in a single catchment, namely river Vesdre (700 km2). Considering this catchment as a case study, we investigate whether available data enable detecting surprise and levee effects and, if so, whether the distribution of such effects shows a particular spatial pattern.To explore this, we apply relatively simple data analysis based on official flood hazard maps, field surveys, as well as outcomes of hydrological and hydrodynamic modelling. The field surveys are twofold. On one hand, inundation depths were registered for 8,000 buildings and infrastructures in the considered catchment. On the other hand, detailed interviews were conducted with flood victims. Information was collect on: flow characteristics, building features, damage and monetary losses, as well as implemented precautionary measures and warning.Data analysis shows that the mismatch between the observed inundation extent and the official hazard maps varies strongly from one section of the river to another, particularly between municipalities. These variations could be related to the presence of flood defense constructed along specific sections of the river, and the associated levee effects. Another quantity which varies enormously from one municipality to another is the ratio between the number of flooded buildings in a municipality to the total number of buildings in the same municipality. This quantity may reflect the degree of overwhelming of local authorities and first respondents, though it is not accounted for in current flood damage modelling.The outcomes of the data analysis contribute to explain differences in how local authorities and communities reacted during this unprecedented flood. Overall, the results highlight the relevance of initiatives undertaken since the event for updating the official flood hazard maps based on more extreme scenarios aiming at enhancing risk awareness. It also emphasizes the need for improved management of residual risk in the case of channelized rivers, or rivers equipped with high-standard flood defences.We are currently exploring to which extent the differences in the level of surprise and levee effects contribute to explain differences in damage and monetary losses between municipalities.
Anistropy in the Earth's inner core
Authors: Deuss Arwen , Brett Hen , Tromp Jeroen
Published: February 2023

The Earth's inner core is one of the most strongly anisotropic regions of our planet. On average, the anisotropy appears to be aligned with the Earth's rotation axis with a larger wave velocity in the polar (North-South) direction than in the equatorial (East-West) direction. Over de last few decades, seismic studies of inner core anisotropy have revealed regional variations with ever increasing detail, suggesting that the top 60-80 km of the inner core is isotropic, the western hemisphere is more strongly anisotropic than the eastern hemisphere and that the anisotropy in the innermost inner core has an anomalous slow direction. Most previous studies assumed that the symmetry axis of the anisotropy is aligned with the rotation axis axis and then attributed regional variations to variations in the magnitude of the anisotropy. Here, we make a tomographic model of inner core anisotropy using seismic body waves observations using a different approach. We assume that the inner core is made of cylindrically symmetric anisotropy crystals that all have the same magnitude of anisotropy, and instead we allow the symmetry axis to vary. We find that our model fits the body wave data equally well as models in which the magnitude varies, with the advantage that our model requires fewer parameters. In our model, the anisotropy in the central part of the inner core is still mainly aligned with the rotation axis. In the upper part of the inner core we find two caps around South-East Asia and Central America with anisotropy aligned parallel to the inner core boundary.Inner core anisotropy is most likely due to alignment of hcp iron crystal  formed either (i) during solidification at the inner core boundary or (ii) afterwards by deformation deeper in the inner core. Thus, our new model may be related to flow in the inner core or solidification processes at the inner core boundary and constrain geodynamic processes in the inner core. 
Gridded Lagrangian surface drifter observations in the North Sea: An overview on high resolution tidal dynamics and surface currents
Authors: Deyle Lisa , Meyerjürgens Dr. Jens , Badewien Dr. Thomas
Published: February 2023

A data set detected by a high-resolution Lagrangian surface drifter is presented for the North Sea from 2017-2021. The North Sea is a marginal sea and is considered a shallow water shelf for most of its area, making its oceanographic dynamics quite different from those in the deep ocean. In contrast, it is less dominated by baroclinic dynamics but is strongly driven by tides, which results in a significant difference in the circulation patterns of particle motions. Numerous Lagrangian drifter observations have been deployed to gain a better understanding of the current behavior at the sea surface. Compared to Eulerian approaches and remote sensing methods, such as high-frequency radars and satellite altimeters, the Lagrangian measurement method can resolve fine current structures at spatial and temporal scales while covering a large region. In addition, Lagrangian methods are variable in space and time, allowing analysis of fine submesoscale fluid dynamics, such as divergence and eddy dynamics, by using clusters of drifters.The methods suitable for calculating surface and tidal currents using drifter position data are presented. Thus, using the large amount of data collected from 2017 to 2021, this study provides a high-resolution mean surface current map and gridded representation of tidal dynamcis in the North Sea. Significant differences between the shallow water shelf and the deep area of the North Sea become apparent. While tidal currents dominate the shallow coastal areas, deep areas such as the Skagerrak register a high mean residual circulation driven by high density gradients. Comparison with other measured data proves that the chosen methods to calculate the currents are reliable. This presents the potential for Lagrangian measurements by surface drifters and the capability of the already detected data set, as it can be used for further analysis and to advance and calibrate numerical models.
The Poggio Baldi Natural Laboratory: an experimental and permanent monitoring site for the assessment of rockfall phenomena
Authors: Cosentino Antonio , Santicchia Giacomo , Mastrantoni Giandomenico , Kundu Jagadish , Mazzanti Paolo
Published: February 2023

In the last decades, technologies such as LiDAR, terrestrial and satellite SAR interferometry (InSAR) and photogrammetry demonstrated a great potential for rock slope assessment. However, studies and applications are still limited for ArcSAR Interferometry, Gigapixel imaging, Acoustic sensing and PhotoMonitoring. With an aim to explore deeper potentials of all above mentioned techniques in monitoring rockfalls and the related debris talus, a permanent natural monitoring site was founded in Poggio Baldi landslide (Central Italy) with various remote monitoring instruments. In detail, the annual volume lost from the cliff is about 3x103 m3 due to frequent rockfalls (up to 84 in three days). Officially inaugurated in October 2021, the permanent Natural Laboratory of Poggio Baldi is completely energy independent and remotely controlled, thus allowing a continuous and efficient monitoring of the rock slope. It is equipped with optical tools (multi resolution cameras), 3D modelling tools (LiDAR and drone photogrammetry), radar tools (linear and arc GB-InSAR, and doppler radar), acoustic tools, seismic tools (sound level meter and geophone) and a weather station. Thanks to the Department of Earth Sciences of the Sapienza University of Rome and NHAZCA SRL for the foundation, contribution, and continuous management of the site. The Poggio Baldi natural laboratory is now continuously monitoring the mass movement activities in a failed slope in Poggio Baldi. The goal is to understand the relationship between rockfalls, predisposing and triggering factors such as thermal, seismic, and meteorological stress that can provide critical information for setting up early warning systems. The acquired data are frequently analysed to assess and improve the prevailing facilities. Additionally, various tools, techniques and methodologies are being developed and implemented at the site to further enhance the capabilities of the monitoring activity. The laboratory is open to host third-party companies and research agencies for testing experimental instruments related to rock and slope deformation and associated risks.
Extreme Precipitation in Tropical Squall Lines
Authors: Abramian Sophie , Muller Caroline , Risi Camille
Published: February 2023

Squall lines are the consequence of the interaction of low-level shear with cold pools associated with convective downdrafts. Beyond a critical shear amplitude, squall lines tend to orient themselves at an angle with respect to the low-level shear. While the mechanisms behind squall line orientation seem to be increasingly well understood, uncertainties remain on the implications of this orientation. Roca & Fiolleau 2020 show that long lived mesoscale convective systems, including squall lines, are disproportionately involved in rainfall extremes in the tropics. One may then question whether the orientation of squall lines has an impact on rainfall extremes, and if so, why.Using a cloud-resolving model, we perform idealized simulations of tropical squall lines by imposing a vertical wind shear in radiative-convective equilibrium. Our results show that precipitation extremes in squall lines are 40% more intense in the critical case and remain 30% superior in the supercritical regime. With a theoretical scaling of precipitation extremes (Muller & Takayabu 2019), we show that the condensation rates control the amplification of precipitation extremes in tropical squall lines, mainly due to its dynamic component. The critical case is not only optimal for squall line orientation, but also for the cloud base velocity intensity of new convective cells.
Reconciling disagreement on global river flood changes in a warming climate
Authors: Zhang Shulei
Published: February 2023

An intensified hydrological cycle with global warming is expected to increase the intensity and frequency of extreme precipitation events. However, whether and to what extent the enhanced extreme precipitation translates into changes in river floods remains controversial. Here, we demonstrate that previously reported unapparent or even negative responses of river flood discharge (defined as annual maximum discharge) to extreme precipitation increases are largely caused by mixing the signal of floods with different generating mechanisms. Stratifying by flood types, we show a positive response of rainstorm-induced floods to extreme precipitation increases. However, this response is almost entirely offset by the concurrent decreases in snow-related floods, leading to an overall unapparent change in total global floods in both historical observations and future climate projections. Our findings highlight an increasing rainstorm-induced flood risk under warming and the importance of distinguishing flood-generating mechanisms in assessing flood changes and associated social-economic and environmental risks.
Thawing permafrost in retrogressive thaw slumps leads to higher N availability
Authors: Fiencke Claudia , Marushchak Maija E. , Wegner Rica , Beer Christian
Published: February 2023

Currently, 20% of the Northern Hemisphere is affected by thermokarst, with an increase expected in future. In particular, ice-rich Yedoma sediments are susceptible to abrupt thaw, which leads to the formation of retrogressive thaw slumps (RTS). These erosion processes result in loss of vegetation, expose long-term frozen permafrost sediments at the surface, and makes soil organic matter (SOM) available for mineralization. Permafrost-affected soils of RTS exhibited higher N availability, as indicated by higher δ15N content of bulk soil, higher nitrate content and higher microbial N turnover (N mineralization especially net nitrification and denitrification) associated with high abundance of functional N genes compared to undisturbed soils. This elevated N availability results in significant emission of the greenhouse gas N2O, especially from exposed permafrost. Based on measured N2O emissions, N2O loss could be as high as 54.8 mg N2O-N per year, which is 0.14% of the initial inorganic N content of exposed Yedoma. The higher N availability of eroded permafrost-affected soils might affect C mineralization because eroded soils had lower aerobic CO2 production than undisturbed soils and CH4 production was detectable in laboratory incubations only in the absence of N2O production.
Determining the shear velocity structure of the oceanic crust from measurements of seafloor compliance
Authors: Aminian Mohammad-Amin , Stutzmann Eléonore , Montagner Jean-Paul , Crawford Wayne
Published: February 2023

The ocean covers two-thirds of the Earth's surface, making it difficult to study the structure of the Earth in these areas.  The ocean, however, provides a pressure signal that can be used to study the oceanic crust, by measuring the seafloor deformation under this pressure signal.  We use continuous signals of seismic ground velocity combined with differential pressure at the sea floor recorded by ocean bottom stations (OBS).  By combining pressure and displacement data of the OBS, we can calculate the compliance function from the pressure signal of infra-gravity waves in the frequency band (0.003-0.03 Hz) . The displacement depends on the seismic properties of the earth's crustal layers, primarily its shear modulus.The compliance function is very sensitive to the regions with a low shear velocity which makes it an excellent tool for investigating the earth crust for these regions.To calculate the compliance function, the data must be preprocessed in several steps including glitch and earthquake removal, tilt correction, etc.To remove earthquakes we used earthquake catalogs for large events and a recursive STA/LTA algorithm for local events. We use a combfilter to remove hourly glitches  produced by the internal OBS system . Tilt noise is caused by deep ocean currents,  we minimize it on the vertical record by rotating the 3-component seismic data to an angle that minimize the variance of the vertical record, then by removing noise coherent with the horizontal components.In this study, we used the French OBS of the Rhum-Rum experiment (Barruol and Sigloch, EOS, 2013) near La Reunion Island for 13 months in 2012, then calculated the compliance function. The crustal shear velocity structure below each station is then recovered by depth inversion of compliance.
Crack-seal veins: records of 600-million-year complex tectonic and fluid flow evolution in Saudi Arabia
Authors: Herlambang Adhipa , Koeshidayatullah Ardiansyah , Lu Chaojin , Amao Abduljamiu , Bello Abdulwahab , Al-Ghamdi Faisal , Malik Muhammad , Al-Ramadan Khalid
Published: February 2023

The Ediacaran Period (635-538 Ma) was marked by considerable tectonic activity, including the end of the Pan-African episode – a long interval of mountain building, rifting, and reorganization spanning most of the Neoproterozoic Era. In Saudi Arabia, the Ediacaran outcrops were developed and preserved in several isolated half-grabens linked to the Ediacaran to early Cambrian Najd strike-slip fault system. This fault system manifested, particularly in the study area, as intensive fractures with a distinctive crack-seal veins morphology. Understanding the mechanism and origin of such fractures could provide unique insights into the structural evolution and paleo fluid flow throughout the history of the Arabian Plate. However, no studies have focused on different structural-controlled diagenetic processes in the Neoproterozoic sequences across the Arabian Plate. Here, we examined precipitated veins along a well-exposed 300 m thick Ediacaran host rock exposure by integrating high-resolution geochemical analyses, carbonate clumped isotopes, fluid inclusions, advanced petrography analysis of Cathodoluminescence microscopy to unravel the structural diagenesis of these Ediacaran strata. The δ18O and δ13C of the carbonate host rocks vary from -11.79 to -7.83‰, and -0.58‰ to 1.1‰, respectively. The estimated paleotemperature of the host rock derived from the clumped isotope is 47-60°C. Furthermore, the current results show that the calcite veins appear in different stages, orientations, geometries, and mineralogy. The δ18O and δ13C of the crack-seal veins vary between -11.2 to -7.8 ‰ and -2.9 to 1.9‰, respectively. The estimated clumped-derived paleotemperature of this vein is 95°C, even higher up to 136°C by utilizing the fluid inclusions. On the other hand, the Mn-rich later phase veins, which cross-cut the crack-seal veins, indicate an isotopic composition of -10.9 to -10.6‰ for δ18O and -18.2 to -15‰ for δ13C, with the estimated paleotemperature of 74-84°C. Hence, we argue that the structural diagenesis history in the study area comprises several distinct tectonic events and fluid circulation members along the fractures associated with different stages of basin evolution. Our findings, for the first time, offer a new understanding of paleo fluid circulation and also highlight the multi-proxy’s potential for investigating the structural diagenesis of calcite veins in the Ediacaran host rock in Arabia.
A narrative of climate states as represented through cultural use and re-use of stone in local societies
Authors: Bruun John
Published: February 2023

As a climate physicist  - I’m conscious we can use the evidence in the environment around us to help attribute and understand how we adapt to environmental changes. The stones in our vicinities, their use and the geo weathering over long time periods gives us clues to older indigenous societies and the choices made in their cultural epochs.  In this discussion I’ll discuss how society changes over the past 2000 years can be a) assessed using formal methods of signal analysis using paleo and instrumental data record, b) interpreted through the clues provided by stone use/ re-use and weathering evidence and c) known alterations to the climate dynamics in given localities. Examples will be drawn from the localities influenced by long term Pacific and Atlantic climate processes, and the interpretation of how society choices have functioned through their use of stone will be debated.
Flooding Induced Seismicity in the Ruhr Area – a geomechanics numerical modelling approach
Authors: Niederhuber Thomas , Rische Martina , Röckel Thomas , Müller Birgit , Schilling Frank
Published: February 2023

The Ruhr region is characterized by centuries of coal mining at depths reaching more than 1000 meters. After the closure of the last mines, their controlled flooding started. The Floodrisk project investigates ground uplift, stress changes due to pore pressure changes and the reactivation potential of faults to explain induced seismicity. We focused on monitoring the eastern Ruhr area and are investigating in detail the relationship between mine water rise, tectonic stress and induced seismicity in the Haus Aden drainage area.In the region of the former "Bergwerk Ost", which had the highest seismicity in the Ruhr area during active mining, the RUB has installed a network of up to 30 short-period seismic stations. Continuous monitoring of seismicity and mine water levels is available for this region from the active mining phase through the post-mining phase to flooding. The temporal evolution of the mine water level after the pumps were shut down in mid-2019 shows a strong correlation with the temporal evolution of the observed microseismicity. Over 2200 induced events have been located since the beginning of flooding, showing spatial clustering. A comparison of the mine galleries, which today serve as the main underground waterways, with the localizations of the events shows that most of the events occur about 300 m below the main pillars located between the longwall panels.This study provides a compilation of the regional stress state in the eastern Ruhr area based on the mine measurements, which were re-evaluated to derive the regional stress component and compared with stress orientations from independent sources (information on stresses in deep boreholes and earthquake focal mechanisms). The spatial distribution of stress orientations in the Ruhr region shows a rather homogeneous stress pattern with only very few locations where stress orientations differ significantly from the average.Based on the geometry of the pillars, shafts and longwall panels, a generic numerical FE-model was developed using the compiled stress data for model calibration. The results indicate increased vertical stresses within and below the pillars as a result of stress arching. The horizontal stress changes are minor, thus differential stress increases in the vicinity of the event localizations.
Land surface models and vertical gradient estimation of evapotranspiration and other turbulent fluxes
Authors: Marti Belen , Boone Aaron , Martinez-Villagrasa Daniel , Cuxart Joan , Price Jeremy
Published: February 2023

The Land surface Interactions with the Atmosphere over the Iberian Semi-arid Environment (LIAISE) campaign took place in Catalonia near Lleida, in the northeastern part of the Iberian Peninsula. It lasted from April to October with an intensive measurement period for the last half of July, 2021, when surface conditions between a large irrigated area and the much drier surroundings was maximum. Measurements of surface energy fluxes and atmospheric and soil conditions were made over several locations which comprised several crop types in irrigated, drip irrigated and non irrigated areas. These data were used to test the quality of the approximations made when modeling in semi-arid environments.  Turbulent fluxes can be estimated using two measurements at different heights of the relevant atmospheric variable with statistically-based methods like Monin-Obukhov theory or simulated from LSMs (Land Surface Models). For latent heat flux, the first approach is limited by the lack of development of the necessary functions when they are used in locations with different conditions from which they were originally developed. The second requires the determination of many parameters which depend on large scale databases or a derived land cover classification to be accurate, together with an appropriate parameterization of the physical processes. Furthermore,  evapotranspiration (ET) estimates for the LIAISE sites are affected by more complex interactions such as the heterogeneity of the region, with areas irrigated by flooding (mainly corn and alfalfa) or drip irrigation (e.g. fruit trees, vineyards) verses relatively dry rain-fed surfaces (natural grass or low vegetation, bare soil), and sudden man-induced changes such as flooding or harvest.      The relationship between the lower atmospheric vertical gradients and fluxes is explored and the LSM SURFEX (Surface Externalisée in French) is evaluated with field data of LIAISE to test its ability to simulate the key processes modulating the surface fluxes (notably the impact of irrigation) over several contrasting sites.