bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatio-temporal analysis of surface displacements in N’Djamena, Chad derived by Persistent Scatter-Interferometric Synthetic Aperture Radar (PS-InSAR) and Small BAseline Subset (SBAS) techniques
Authors: Rygus Michelle , Tessari Giulia , Holecz Francesco , Vogt Marie-Louise , Daïra Djoret , Destro Elisa , Isseini Moussa , Origgi Giaime , Ndjoh Messina Calvin , Meisina Claudia
Published: March 2022

High-resolution characterisation of land deformation and its spatio-temporal response to external triggering mechanisms is an important step towards improving geological hazard forecasting and management. The work presented here is part of the ResEau-Tchad project (www.reseau-tchad.org), with a focus on the city of N’Djamena. The extraction of groundwater to sustain this rapidly growing capital city has increased the pressure on water supply and urban sanitation infrastructures which are failing to meet the current water demand. In this study we exploit Synthetic-Aperture Radar (SAR) data acquired by the Sentinel-1 satellite to investigate the temporal variability and spatial extent of land deformation to assist in the development of a sustainable water management program in N’Djamena city. 

The objectives of the work are: 1) to analyse the recent evolution of land deformation using two multi-temporal differential interferometry techniques, SBAS and PS-InSAR; and, 2) to investigate the land deformation mechanism in order to identify the factors triggering surface movements. The PS-InSAR and SBAS techniques are implemented on SAR images obtained in both ascending and descending orbits from April 2015 to May 2021 to generate high resolution deformation measurements representing the total displacement observed at the surface. While the pattern of displacement indicated by the two datasets is similar, the average velocity values obtained with PS-InSAR tend to be noisier than the ones derived using the SBAS technique, particularly when the SBAS time-series shows non-linear deformation trends.

Characterisation of the subsidence areas by means of statistical analyses are implemented to reveal the surface deformation patterns which are related to different geo-mechanical processes. The integration of the spatio-temporal distribution of PS and SBAS InSAR results with geological, hydrological, and hydrogeological data, along with subsurface lithological modelling shows a relationship between vertical displacements, clay sediments, and surface water accumulation. These areas are located mostly in the surroundings of the urban area. The city centre is observed to be mostly stable, which might be the result of the removal of the surface water through the city drainage system. Investigation of the relationship between vertical displacements and seasonal groundwater fluctuations or effects due to the groundwater withdrawal is limited due to the temporally sparse piezometric dataset; however, the recent deformation rates appear to be correlated with the groundwater level trend at some locations.
Monitoring drought impact on vegetation with Sentinel-1
Authors: Vreugdenhil Mariette , PFeil Isabella , Steele-Dunne Susan , Dorigo Wouter
Published: March 2022

With the Copernicus Sentinel-1 series, for the first time high temporal and spatial resolution backscatter time series have become available. Sentinel-1 backscatter observations are sensitive to changes in water content and structural changes in vegetation and soils and provide complementary information next to optical remote sensing datasets such as Leaf Area Index. However, most studies have looked at the sensitivity of Sentinel-1 backscatter to vegetation water dynamics at very local scale. Furthermore, no specific focus has yet been on monitoring drought impact on vegetation with Sentinel-1. Here we will present results of a study over Europe which assesses the potential of Sentinel-1 to monitor drought impact on vegetation.

In this study we use the record summer drought of 2018 as a case study. This drought led to decreased yields in northwestern Europe, and to decreased GPP in for example grasslands and forests (Fu et al., 2020). We have calculated anomalies of co-, and cross-polarized backscatter, and the ratio thereof, the so-called cross-ratio (CR) of 2018 with the reference year of 2016 which had normal conditions. These anomalies were compared to anomalies calculated with Copernicus Global Land Service LAI anomalies and ESA CCI soil moisture anomalies and analyzed per land cover type. The results show very strong negative anomalies in VV, VH backscatter and CR from June to November over central and northwestern Europe, similar to those observed in LAI. However, differences in patterns can be seen between LAI and CR, especially over forest areas. Although LAI showed stronger anomalies in the Netherlands and western Germany in July, CR shows stronger anomalies in eastern Germany and Czech Republic, and especially over forests. These differences in patterns may be related to the penetration depth of microwaves, and the sensitivity to vegetation water content of the above ground biomass.
A complex hazard assessment due to earthquake and tsunami potential in the industrial strategic estate of the Cilegon city 
Authors: Anugrah Suci Dewi , Yatimantoro Tatok , Julius Admiral Musa , Daryono Daryono , Hidayanti Hidayanti , Yogaswara Debi Safari , Anggraini Septa , Simangunsong Gloria , Kriswinarso Tribowo , Harvan Muhammad , Karnawati Dwikorita , Prayitno Bambang Setiyo , Adi Suko Prayitno
Published: March 2022

Due to the existence of the megathrust, south of Sunda Strait potentially generate the powerful earthquake and tsunami. It may impact to South of Java Island and Sunda strait coastal zone. One of the city that may impacted by the earthquake and tsunami is the Cilegon city located in the north-east of Sunda Strait. The city is the strategic area which has industrial estate, critical infrastructures, as well as a tourist destination. The earthquake and tsunami hazard may followed by the collateral hazard. 78 petrochemicals factory as well as steel industry, and other national vital object such as electric stream power plant could give a contribution to the industrial hazard.

Based on a seismological study, the maximum magnitude estimated in megathrust zone Sunda Strait is M 8.7. The existing of active faults and active volcano of Krakatau in Sunda Strait add a complexity of earthquake and tsunami potential in the area. According to historical documentation, there are destructive earthquake associated to south of Sunda Strait megathrust such as West Java earthquake (January 5, 1699), Batavia earthquake (January 22, 1780), Jakarta Earthquake (February 23, 1903), and destructive tsunami associated to the Krakatau eruption (August 27, 1883).

This study aims to assess the multi hazard potential generated by the megathrust earthquake in the south of Sunda Strait. We simulate the worst case earthquake scenario on the south of Sunda Strait megathrust zone, located at 7.53 S;104.04 E, with 10 km fixed depth. Both simulation of earthquake shakemap and tsunami inundation were carried out in this study.

The modeling of earthquake indicates ground shaking possibly generates VI-VII MMI in Cilegon. Moreover, the inundation tsunami modeling estimated there are 4 sub-regencies of industrial estate (Ciwandan, Citangkil, Gerogol, and Pulomerak) will be impacted. The highest tsunami inundation may approximately reach 9 m hit a critical infrastructure of the Merak harbor. The maximum distance of tsunami penetration is estimated to be 1.5 km from the coastal line.

Keywords: earthquake and tsunami potential, multi collateral hazard, industrial estate, cilegon city, critical infrastructure
Modelling of Mercury's crustal structures from gravity data inversion
Authors: Buoninfante Salvatore , Milano Maurizio , Negri Barbara , Plainaki Christina , Sindoni Giuseppe , Fedi Maurizio
Published: March 2022

NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission has provided a wealth of geophysical data that, under some limitations, can be used to determine the internal properties of the planet. Here we investigate the HgM008 global gravity field model to interpret the crustal structures of Mercury generating large-scale gravity anomalies observed at satellite altitudes. While the Bouguer anomalies calculated in previous studies are based on the assumption of a homogeneously dense crust, in this work we compute the isostatic anomalies which are expected to be representative of the intra-crustal sources, the main targets of our study. To this end, we focused on the Northern Rise region, characterized by a better data resolution according to the HgM008 model. The isostatic anomalies are computed by assuming the Vening Meinesz isostatic compensation model for spherical harmonic coefficients in the degree and order range 5-80, according to the calculated flexural isostatic response curve. We selected a mean elastic lithosphere thickness of 30 km, as it yielded isostatic anomalies rather unrelated to both free-air anomalies and topography. We then interpreted the isostatic anomalies of Northern Rise area with a least-squares inversion algorithm assuming a tesseroid-layered model of the crust. This anomaly may be interpreted as a mantle uplift event following a strong meteoritic impact.

 
A python package for fast interior modelling of terrestrial (exo-)planets using a Gibbs free energy minimization
Authors: Seidler Fabian , Wang Haiyang , Quanz Sascha
Published: March 2022

With increasing capabilities of characterizing small rocky exoplanets beyond our solar system, the question of their chemistry, geology and interior structure arises. Accompanied by observational facilities capabale of giving a deeper look into this topic than ever before, modelling of the interior structure of exoplanets has become a standard procedure in the emerging field of exogeology. Most often, these research uses a simplified mineralogy – consisting of the major phases formed by  MgxFe1-xSiO3 and Mg2xFe2(1-x)SiO4 -  to construct the density profile of the planets mantle. Others have used the more sophisticated, but computationally expensive procedure of Gibbs free energy minimization to find the mantle equilibrium mineralogy (and hence its thermodynamical properties) from the first order chemistry of the planet. Here, we present a new Python/Cython software package capable of quickly inferring exoplanet interior structure by using a linearized Gibbs free energy minimization procedure - written in Cython - along an adiabatic mantle gradient. This simplifies and speeds up the interior structure modelling, reaching a runtime of ~7 seconds on a standard desktop PC for an Earth-sized planet, compared to ≥ 2 minutes with another interior structure and mineralogy solver, ExoPlex. We will demonstrate the use of the codes and its first application results at the assembly.
Soil warming duration and magnitude affects dynamics of fine-roots and rhizomes and C and N pools in belowground biomass in subarctic grasslands
Authors: Bhattarai Biplabi , D. Sigurdsson Bjarni , Sigurdsson Páll , Leblans Niki , Janssens Ivan , Truu Jaak , Truu Marika , Kumar Devarajan Arun , Ostonen Ivika
Published: March 2022

Climate predictions for arctic and subarctic regions show a higher rise in surface temperature than the global mean, which will subsequently raise the soil temperature (Ts) in those regions. We investigated the effects of soil warming duration (medium-term (11-yr) vs. long-term (>60-yr) warmed grassland) and magnitude from +0.2 to +6.2 °C on total belowground plant biomass (BPB) as well as in two functional groups: short-living fine-roots and long-living rhizomes in topsoil (0-10cm) and subsoil (10-30cm). We also analyzed the effect of plant community composition on belowground biomass and pools.

Both the duration and the magnitude of soil warming influenced the dynamic of total belowground biomass (BPB) and fine-roots and rhizomes separately. The soil warming effect varied along the soil depths. Both changes in carbon and nitrogen concentration in fine-roots and rhizomes and their corresponding biomass contributed to the significant decline in carbon and nitrogen pool in belowground plant biomass along the warming gradient. The change in the functional structure of the plant community was related to the increase in soil temperature. The proportion of forbs increased towards warmer plots and was related to the change in the BPB and soil chemistry. Our findings underline the importance of a functional approach in root research to understand better the key physiological processes like N and C cycling. We highlight the role of soil chemistry and community changes together with warming (duration and magnitude) in the fine-root and rhizome response to climate change. 
Inside the fault core in the footwall of Simplon Fault Zone (Central Alps): ductile to brittle deformation history shown by fault gouge
Authors: Argante Valentina , Tanner David Colin , Brandes Christian , Von Hagke Christoph , Tsukamoto Sumiko
Published: March 2022

For thorough understanding of the dynamics of mountain building processes, it is crucial to reconstruct the youngest crustal deformation history over time. Low-angle normal faults are features caused by orogen-parallel extension, which occurs in the last stage of collision. Low-angle normal faults play a key role in the exhumation of the lower crust and they are the reason for most of the seismicity within the chain.

We carried out microstructural analyses on an outcrop in the footwall of one of the major normal faults of the Alpine chain, the Simplon Fault Zone. This low-angle normal fault extended the crust by tens kilometers and it caused exhumation of its footwall, the deeper lower crust of the Alps, i.e. the Penninic nappes. The Simplon Fault Zone itself consists of a thick mylonitic zone overprinted by a narrow cataclastic zone, with the same kinematics. Its timing evolution history from ductile to brittle deformation is still under discussion. This study shows a new microstructural analysis from a fault gouge within the footwall of the northern part of the Simplon Fault Zone, and how it can reconstruct the different stages of exhumation history of this shear zone.

Results from micro-structural analyses show grain boundary migration features on folded quartz veins. This suggests that the protolith of the fault zone was at high temperature conditions, T>600°C, during dynamic deformation. This folding belongs to extension-parallel folds that affect only the ductile shear zone. The presence of greenschist facies minerals suggests that the rock was exposed to low temperature and pressure conditions (T=300-400°C, P=0.2GPa). Pressure-solution mechanisms affect both quartz and greenschist paragenesis, indicating formation in a shallow position of the shear zone. The last deformation was purely brittle, as shown by vertical calcite veins or fractures in quartz. It suggests a near-surface position of the fault.

Altogether, these multiple deformation phases within the gouge samples indicate a continuous exhumation history from high to low temperatures, with clear cross-cutting relationships. However, the lack of cataclasite features can be related to an involvement of the rocks within the fault core in a subsequent stage of deformation. To explain this we suggest a model in which the footwall maintained a high temperature over a long time, which inhibited cataclastic processes.
Response time correction of membrane equilibrium based methane sensor data
Authors: Dølven Knut Ola , Vierinen Juha , Grilli Roberto , Triest Jack , Férré Bénédicte
Published: March 2022

High resolution measurements with acceptable accuracy are crucial to increase our understanding of important environmental processes. The sharp spatial and temporal gradients which characterize seabed seepage environments often means that conventional measuring techniques fall short in representing seepage, content, and the environmental processes of interest. This is especially the case when it comes to measuring dissolved methane, which is still often done using discrete water sampling and subsequent laboratory analysis. This practice is time consuming, resulting in data with poor spatiotemporal resolution which is often unable to represent highly variable environmental processes. The overt solution to this problem is the employment of in situ sensors. Unfortunately, the common sensor design approach in off-the-shelf sensors, where measurements rely on a membrane equilibrium extraction technique and gas detection by some embedded device, are, while theoretically reliable, often plagued by high response times – especially in cold environments, making them unsuitable for applications where rapid changes are expected.

We present a new, easily applicable, lab and field-tested method for recovering fast response data from off-the-shelf methane sensors relying on the principle of membrane separation by using the theoretical framework of statistical inverse theory. This framework allows us to model the uncertainty of the measurements obtained by the internal detector, giving fast response data where measurement uncertainty is explicitly defined – something which has not been possible in the past. The solution is constrained by model sparsity, which in practice gives the user data with the resolution at which the sensor is able to give measurements with a reasonable uncertainty. Furthermore, our method requires no additional input from the user other than what is provided from the manufacturer, such as detector accuracy and response time. Getting reliable fast response data from relatively affordable, off-the-shelf in situ sensors, means that these can be used in new applications such as profiling, towing, or on autonomous platforms such as gliders. This can considerably improve our ability to quantify dissolved methane and resolve and understand related environmental processes in the ocean.
Improving past and future relative sea-level constraints for the Norwegian coast
Authors: Lakeman Thomas R. , Nixon F. Chantel , Romundset Anders , Simpson Matthew J.R. , Svendsen John Inge , Vasskog Kristian , Bondevik Stein , Milne Glenn , Tarasov Lev
Published: March 2022

New research aims to improve relative sea-level (RSL) projections for the Norwegian coast. The main objectives are to: i) collect observations of past RSL changes, ranging from the end of the last ice age to the last century, ii) develop a high-quality database of post-glacial sea-level index points (SLIPs) for the Norwegian coast, and to iii) improve our understanding of past and future vertical land motion using glacial isostatic adjustment (GIA) modelling. To now, our collection of new empirical data has focussed on three significant, but enigmatic RSL histories that are not adequately reproduced in existing GIA models: very recent stillstands and transgressions documented by historical tide gauge records, rapid transgressions during the early- to mid-Holocene Tapes period, and abrupt transgressions during the latest Pleistocene Younger Dryas chronozone. Ongoing field sampling is focussed on developing high-resolution RSL trends from salt marshes, isolation basins, and raised beaches, using multiple biostratigraphic and geochemical proxies (i.e. micropaleontology, macrofossils, x-ray fluorescence, C/N) and dating techniques (i.e. Pb-210, Cs-137, C-14, tephrochronology, geochemical markers). Results from various localities spanning the Norwegian coast provide robust constraints for the timing and rate of RSL change during the Younger Dryas and Tapes chronozones. Additional results providing new estimates of very recent RSL trends in southwest Norway are presented by Holthuis et al. (Late Holocene sea-level change and storms in southwestern Norway based on new data from intertidal basins and salt marshes; Session CL5.2.2). These new and emerging constraints are being integrated into a post-glacial RSL database that incorporates high-quality data from the entire Norwegian coastline. Over 1000 SLIPs have been assembled from published studies. These existing data were updated using current radiocarbon calibration curves, high-resolution digital elevation models, new field observations, and new quantitative estimates of relevant uncertainties. Ongoing GIA modelling is utilizing the new RSL database, a glaciological model that freely simulates ice sheet changes, as well as geodetic and ice margin chronology constraints, to develop rigorous uncertainty estimates for present and future GIA along the Norwegian coast.
Interpretable Deep Learning for Probabilistic MJO Prediction
Authors: Christensen Hannah , Delaunay Antoine
Published: March 2022

The Madden–Julian Oscillation (MJO) is the dominant source of sub-seasonal variability in the tropics. It consists of an Eastward moving region of enhanced convection coupled to changes in zonal winds. It is not possible to predict the precise evolution of the MJO, so subseasonal forecasts are generally probabilistic. Ideally the spread of the forecast probability distribution would vary from day to day depending on the instantaneous predictability of the MJO. Operational subseasonal forecasting models do not have this property. We present a deep convolutional neural network that produces skilful state-dependent probabilistic MJO forecasts. This statistical model accounts for intrinsic chaotic uncertainty by predicting the standard deviation about the mean, and model uncertainty using a Monte-Carlo dropout approach. Interpretation of the mean forecasts from the neural network highlights known MJO mechanisms, providing confidence in the model, while interpretation of the predicted uncertainty indicates new physical mechanisms governing MJO predictability.
Modulation of Tropical Cyclone Activity and Rainfall by the North Atlantic Oscillation
Authors: Chen Shuyi , mazza Edoardo
Published: March 2022

This study focuses on the influence of the North Atlantic Oscillation (NAO) on interannual tropical cyclone (TCs) activity and rainfall using observational and reanalysis products. Using Poisson regression models, we show that the low-frequency NAO variability is associated with a distinct pattern of TC activity across the North Atlantic basin. Across the western Atlantic, the Caribbean Basin and the Gulf of Mexico, TC activity increases as the NAO decreases: an interquartile range decrease in the NAO corresponds to a 30-40 % increase in TC track density. While the NAO is known to affect the weather regimes of the mid-latitudes, we show that its low-frequency component influences the large-scale environment across Main Development Region. The negative NAO phase is associated with significantly higher Sea-Surface Temperature (SST) and lower tropospheric wind shear. Finally, we investigate whether the NAO influence on TC activity can be detected in the basin-scale variations of TC rainfall. By building monthly rainfall composites from satellite and reanalysis products, we show that TC rainfall is indeed strongly enhanced in the Caribbean and in the Gulf of Mexico during the negative phase of the NAO. Such modulation is particularly evident during neutral or La Niña conditions.
Current changes in seasonal rainfall and the impact of the NAO in Serbia
Authors: Popov Hristo , Svetozarevich Jelena
Published: March 2022

Climate fluctuations are highly dependent on changes in atmospheric circulation. The physical properties of air masses and their geographical distribution are of great importance because they determine the weather over large areas.

The North Atlantic Oscillation (NAO) is the most significant mode of natural climate variability in the Northern Hemisphere. It has a major impact on weather and climate in the North Atlantic and mainland Europe. There are two phases of NAO, positive and negative. When it is positive in Europe, warmer and wetter weather prevails. When it is negative, the weather in Europe is colder with more rainfall.

The Republic of Serbia is located in Southeastern Europe, in the western part of the Balkan Peninsula, the northern part of the country is located in the Middle Danube Lowland, the Sava Valley and the Tisza Valley. In the middle part are the river valleys of Drina, Kolubara and Morava. In the southern part of the country are occupied by mountains up to 2000 m high.

The aim of the article is to study the current changes in seasonal precipitation in the Republic of Serbia. For this purpose, data from 15 climate stations were evenly distributed over the territory and the influence of the NAO during the winter months. Three of the stations are mountainous - located over 1000m. The rest are alpine with lower altitude. The data is for seasonal values 1990-2019 were obtained from NIMH Serbia.

In structure of the research introduction presents the topic, tasks and bibliography. The Data and Methods section shows the geographical and climatic features of the study area and explains the methods. The next section provides results on seasonal changes and the impact of NAO. The conclusion shows the main results we have reached.

Key words:  NAO, climate change, seasonal precipitation, Republic of Serbia
Temporal carbon discharge from coastal erosion and bog burst of tropical coastal peatland in Indonesia
Authors: Yamamoto Koichi , Sutikno Sigit , Kagawa Hiroki , Basir Noerdin
Published: March 2022

Coastal erosion is one of the new but serious problems in the coastal tropical peatlands of Riau.  This coastal erosion occurs on the Malacca Strait side of the peatland in Sumatra Island and fringed small islands.  This coastal erosion is a combination of peat collapse, or bog burst.  The study area is located on Bengkalis Island, Riau Province, Republic of Indonesia.  The region is located at 1.6 degrees north latitude and 102 degrees east longitude and has a tropical rainforest climate.  Temporary UAV observations of the coastal areas of Benkalis Island were carried out, and chemical analysis of peat core samples was performed at several points to estimate carbon storage.  As a result of observation, the annual carbon emission per coastline from coastal peatland is estimated to be 7.8-10tCm-1.  We also used the Sentinel-1 image to assess the number of peaty debris fans appearing as a result of the bog bursts.  The appearance of peaty debris fans showed a clear increase with increasing precipitation.
Identifying drivers of extreme reductions in carbon uptake of forests with interpretable machine learning
Authors: Anand Mohit , Camps-Valls Gustau , Zscheischler Jakob
Published: March 2022

Forests form one of the major components of the carbon cycle and take up large amounts of carbon dioxide from the atmosphere, thereby slowing down the rate of climate change. Carbon uptake by forests is a highly complex process strongly controlled by meteorological forcing, mainly because of two reasons. First, forests have a large storage capacity acting as a buffer to short-duration changes in meteorological drivers. The response can thus be very complex and extend over a long time. Secondly, the responses are often triggered by combinations of multiple compounding drivers including precipitation, temperature and solar radiation. Effects may compound between variables and across time. Therefore, a large amount of data is required to identify the complex drivers of adverse forest response to climate forcing. Recent advances in machine learning offer a suite of promising tools to analyse large amounts of data and address the challenge of identifying complex drivers of impacts. Here we analyse the potential of machine learning to identify the compounding drivers of reduced carbon uptake/forest mortality. To this end, we generate 200,000 years of gross and net carbon uptake from the physically-based forest model FORMIND simulating a beech forest in Germany. The climate data is generated through a weather generator (AWEGEN-1D) from bias-corrected ERA5 reanalysis data.  Classical machine learning models like random forest, support vector machines and deep neural networks are trained to estimate gross primary product. Deep learning models involving convolutional layers are found to perform better than the other classical machine learning models. Initial results show that at least three years of weather data are required to predict annual carbon uptake with high accuracy, highlighting the complex lagged effects that characterize forests. We assess the performance of the different models and discuss their interpretability regarding the identification of impact drivers.
New data on Campanian Ignimbrite of southern Italy: changing paradigm for Campi Flegrei caldera and the Campanian volcanism
Authors: De Natale Giuseppe , Kilburn Christopher R.J. , Rolandi Giuseppe , Troise Claudia , Somma Renato , Fedele Alessandro , Di Vincenzo Gianfranco , Rolandi Roberto , Woo Judith
Published: March 2022

We present a new stratigraphy, inferred from several drillings carried out in the framework of the ICDP Campi Flegrei Deep Drilling Project , for the largest volcanic eruption in Europe since at least the Late Pleistocene. The eruption produced the Campanian Ignimbrite of southern Italy. It is conventionally believed to have triggered collapse of the large Campi Flegrei caldera, which, in turn, has been identified as a source for future ignimbrite volcanism. New borehole and radioisotopic data challenge this interpretation. They indicate that the Campanian Ignimbrite was erupted through fissures in the Campanian Plain, north of Campi Flegrei, and was not responsible for caldera collapse. The results are consistent with ignimbrite volcanism being controlled by a common magmatic system beneath the Campanian Plain. Understanding the dynamics of the whole plain is thus essential for evaluating the likelihood of similar future events.
Climate change analysis of hydrological droughts in Jiet catchment, Romania.
Authors: Beltran Mora Cindy
Published: March 2022

Drought events are more common nowadays than it used to be in the past in different areas around the world. Some of its consequences are the reduction of cropping areas, lower rates of percolation for recharge of aquifers and scarcity of drinkable water. To analyse and identify droughts location, dates of occurrence and severity, it is necessary to collect meteorological data. However, based on the location of the study region, some places do not have measurement stations, hence, spatiotemporal databases are the best alternative. Present paper shows the analysis of the past and future scenarios of hydrological droughts due to climate change in the Jiet river basin in Romania. Spatiotemporal data from remote sensing with different resolutions is analysed and processed. Data from year.1990. to year 2020. At a resolution of 0.1̊ is compared to projection scenario RCp 8.5 during 2030 to 2060.

An assessment of hydrological droughts for past scenarios is made by defining a statistical threshold (85 percentile) from historical data. Further, an analysis of characteristics of hydrological drought events is performed for present and future scenarios. Drought is measured through soil moisture analysis, using results from HEC – HMS v4.9 BETA, hydrological modelling tool. This study presents the results of the first stage of the process were a spatiotemporal analysis of the calibration performance of the of the hydrological model and the droughts found are characterized. 
What can we learn from previous generations? Álftaver’s experience of the 1918 Katla eruption
Authors: Gísladóttir Guðrún , Bird Deanne , Pagneux Emmanuel
Published: March 2022

Residents in Álftaver, south Iceland, are very familiar with the 1918 Katla volcanic eruption, which caused rapid and catastrophic glacial outburst flooding of the area. Descriptions of the 1918 events, passed down by older generations, have become an important part of the collective memory. Based on oral and written history, this paper provides a vivid account, including detailed maps, of what people experienced and felt during the 1918 Katla eruption. It also considers how these experiences influence current-day perceptions and the impact this may have on behavior in relation to emergency response strategies. Until now, much of this history has only been accessible in Icelandic text and through oral stories. The aim of this paper is to unlock these stories for an international audience in an effort to advance understanding of volcanic eruptions and their impacts and, inform future emergency planning. Importantly, these descriptions tell us about the nature of the glacial outburst flood, with a ‘pre-flood’ devoid of ice and travelling at a much faster rate than the ice-laden main flood. As a future eruption of Katla may impact Álftaver, emergency response plans for glacial outburst floods were developed, and in March 2006 preliminary plans were tested in a full-scale evacuation exercise involving residents and emergency response groups. But Álftaver residents questioned the plans and were reluctant to follow evacuation orders during the exercise, as they felt their knowledge and the experience of their relatives during the 1918 Katla eruption, had not been taken into consideration. Residents were concerned that flood hazards, as well as tephra and lightning, were not appropriately accounted for by officials. In response to residents’ concerns, officials developed an alternative evacuation plan (Plan B) that builds on some of the experience and knowledge of Álftaver residents. However, residents were not involved in the development of ‘Plan B’ and they are not aware of what it constitutes or when it is to be implemented. This paper argues that more needs to be done to promote inclusive dialogue and the co-production of knowledge to ensure emergency response strategies adequately reflect and accommodate local knowledge, perspectives and planned behavior.
Travel Time Uncertainty Reduction by Multiobjective Optimisation of Isotope Age Tracer Models
Authors: Petrova Elena , Osenbrück Karsten , Mayer K. Ulrich , Finkel Michael , Grathwohl Peter
Published: March 2022

Quantification of the travel time distribution and transport parameters in fractured aquifers is crucial for understanding contaminant transport in fractured systems. Although knowledge about the travel time distribution is a helpful tool to assess the solute transport, it can’t be measured directly. Travel time is typically back-computed from different tracers in groundwater by applying well established analytical methods. However, in fractured aquifers diffusive exchange with the rock matrix, intersection of streamtubes and associated mixing, as well as other processes can cause deviation of the estimated travel time from the mean advective travel time. Direct numerical modelling of the tracer’s reactive behavior with the travel time as one of the calibrated parameters can lead to non-uniqueness of the result. These non-unique solutions typically lead to a high level of parametric uncertainty especially on catchment scale. In this work, we address the reduction of uncertainty in mean travel time, shape parameter of travel time distribution, fracture aperture, and porosity by means of multiobjective optimization enhanced by surrogate modelling. For pre-selection of potentially plausible model runs Gaussian Processes Emulation (GPE) was applied within four-parametric space. We use the GPE with multitracer conditioning for pre-selection of plausible parameter combinations. Posterior distributions were employed to estimate the mean groundwater travel times at sampling locations, to distinguish between different rock facies of captured streamlines, and to get an estimate of fracture apertures. We confirm the hypothesis that using tritium and helium isotopes together with radiogenic helium measurements helps to achieve a unimodal posterior distribution and reduces uncertainty significantly.
The Naval Seafloor Evolution Architecture: a platform for forecasting dynamic seafloor roughness
Authors: Kearney William , Penko Allison
Published: March 2022

Model predictions of waves, currents, and sediment transport, as well as the acoustic response of the seafloor depend on reliable estimates of seafloor roughness due to both sediment properties and bedform geometry. To predict the spatial and temporal dynamics of seafloor roughness under changing wave conditions, we have developed a modular modeling framework, the Naval Seafloor Evolution Architecture (NSEA). NSEA requires hydrodynamic forcing as input, which can either be directly observed or output from a hydrodynamic model. A nonequilibrium spectral ripple model is driven with this forcing to estimate the power spectrum of the seafloor elevation. Stochastic realizations of seafloor roughness consistent with this power spectrum are generated, which can be used as input to acoustic models to predict the acoustic response of the seafloor. Running ensembles forward through the model allows uncertainty in the hydrodynamic forcing, the sediment properties, and the parameters of the spectral ripple model and acoustic model to be propagated to the model outputs. Bayesian inference can also be applied to solve the inverse problem of estimating the seafloor spectrum and model parameters from observations. We illustrate the features of this model architecture by applying it to estimate seafloor roughness during a field experiment off the coast of Panama City, Florida, USA. We show how NSEA, working in both forward and inverse mode, can use available hydrodynamic models and observations as well as side-scan sonar imagery of the seafloor to estimate changing seafloor roughness with quantified uncertainty.
Multi-hazard open access software package review with the potential for conducting sectoral risk assessments on a European or local scale
Authors: Daniell James , Schaefer Andreas , de Ruiter Marleen , Foerster Evelyne , Ward Philip , Brand Johannes , Khazai Bijan , Girard Trevor , Wenzel Friedemann
Published: March 2022

As part of the NARSIS (New Approach to Reactor Safety ImprovementS, www.narsis.eu) project, and the MYRIAD-EU (Multi-hazard and sYstemic framework for enhancing Risk-Informed mAnagement and Decision-making in the EU, www.myriadproject.eu) project, a compendium of existing open access software packages for risk modelling of natural hazards, as well as a review of multi-hazard projects has been undertaken with a clear focus on assessments in Europe.

There have been over 200 open access software packages produced for the evaluation of singular natural hazards, combinations of natural hazards and multi-hazard identified either propagating through to risk, or calculating extensive hazard metrics. By far, the most have been built for floods, and earthquakes, however a number have been designed for multi-hazard (RiskSCAPE, HAZUS and variants, CLIMADA, NARSIS-MHE, InaSAFE to name a few).

In around 120 of them, they have moved through to risk assessment, with the calculation of risk metrics. Many of these have been designed for scenario analysis, but there are also many which employ probabilistic methods or stochastic models to evaluate risk. In this work, the classification of the open access software packages follows that of previous studies (Daniell et al., 2014), but with a focus on the use for multi-hazard assessment rather than singular hazards.

Moving through to multi-risk, a number include different interconnected systems for assets (OOFIMS for instance from the EU SYNER-G project). Although there are very few that deal with consecutive or coinciding hazards, a number can be adapted to do this, and some even have the ability to be used for cascading hazard analysis.

By understanding the state-of-the-art in existing software packages as of 2022, a multi-hazard framework can be produced for various economic sectors such as ecosystems and forestry, energy, finance, food and agriculture, infrastructure and transport, as well as tourism, to solve some of the missing links when looking at the impacts of consecutive, coinciding or cascading hazards. In addition, relevant software packages have been found to conduct assessments on the European scale, but also on the local scale for more detailed analyses.
The influence of MJO initial condition on the extratropical prediction skills in subseasonal-to-seasonal prediction model
Authors: Kim Hera , Kim Hyeme , Son Seok-Woo
Published: March 2022

    This study examines the impacts of the Madden-Julian Oscillation (MJO) on extratropical prediction skill in the Northern Hemisphere during the extended winter, using subseasonal-to-seasonal reforecasts. All four models examined in this study showed a sensitivity of the prediction skill in the North Pacific basin to the initial MJO amplitude at lead weeks 4 and 5. In the ECMWF model, for example, pattern anomaly correlation coefficient (PACC) skill of 300-hPa geopotential height at week 4 becomes higher when the model is initialized with strong MJO than weak MJO. An improved PACC skill with strong MJO is also found in surface air temperature prediction, primarily over the United States. Although not always statistically significant, the similar results are also found in other three reforecasts. The changes in extratropical prediction skill seem to be linked with the MJO prediction skill and the amplitude of the predicted MJO in the first 3 weeks of forecast lead, both of which are higher with strong MJO at initial state than those without active MJO. In addition, the impact of the MJO initial condition on the extratropical prediction is different for each MJO phase. The prediction skill mainly changes in the region where observed teleconnection pattern is consistent across events for each phase, verifying the causality between the MJO and the extratropical prediction skills.
Nonlinear seismic phenomena as recorded by distributed acoustic sensors
Authors: Gurevich Boris , Yurikov Alexey , Tertyshnikov Konstantin , Lebedev Maxim , Isaenkov Roman , Sidenko Evgenii , Yavuz Sinem , Shulakova Valeriya , Correa Julia , Glubokovskikh Stanislav , Freifeld Barry , Pevzner Roman
Published: March 2022

Due to their granular nature and presence of fluids, elastic moduli of most crustal rocks show a strong stress dependency. This means that the relationship between stress and strain is nonlinear, which should cause nonlinear wave phenomena. In particular, interaction of seismic waves of different frequencies should generate higher harmonics and combinational frequencies. Analysis of these effects in field data can potentially help find areas of anomalous nonlinear properties, such as fractured zones, mixed saturation or overpressure. To better understand the potential of nonlinear seismology, we observed and analyzed nonlinear seismic effects in field and laboratory experiments. The field experiment was performed using two seismic vibrators generating monochromatic signals of different frequencies. The wavefield was recorded with a fiber optic distributed acoustic sensing (DAS) cable cemented in a 900 m deep borehole. The signals recorded both on the surface and in the borehole show combinational frequencies, harmonics, and other intermodulation products of the fundamental frequencies. The laboratory experiment, which was designed to replicate the setup of the field experiment, shows similar nonlinear products of the fundamental frequencies. Furthermore, the nonlinear effects show a dependency on the saturating fluid. These tests confirm that nonlinear components of the wavefield propagate in a form of body waves, are likely to be generated in rock formations, and have the potential for reservoir fluid characterization.
Does interactive ocean dynamics effect North Atlantic SST variability?
Authors: Gozdz Olivia , DelSole Tim , Buckley Martha
Published: March 2022

There is currently disagreement regarding the role of active ocean dynamics in Atlantic sea surface temperature (SST) variations. We investigate this by comparing sea surface temperature variations in a fully coupled atmosphere-ocean-ice model to those in a coupled model in which the atmosphere is coupled to a motionless slab (henceforth slab ocean model). Differences in variability between the two models are diagnosed by an optimization technique that finds components whose variance differs as much as possible between the two models. This technique reveals that SST variability differs significantly between the two models. Thus, the slab and fully coupled model are statistically distinguishable. The two leading components with larger SST variance in the slab model are associated with the tripole SST pattern and the Atlantic Multidecadal Variability (AMV) pattern. This result supports previous claims that ocean dynamics are not necessary for the AMV and, in fact, may be damping it. The leading component with larger variance in the coupled model resembles the Atlantic Nino pattern, consistent with the fact that ocean dynamics are required for Atlantic Nino. The second leading component with larger variance in the coupled model is a mode of subpolar SST variability that is associated with sea surface height variations along the path of the North Atlantic current, suggesting a role for wind-driven ocean dynamics.
Zeta Potential of Fractured Gneiss Saturated with NaCl and Natural Aqueous Solutions – Impact of Composition, Concentration and Fracture Aperture on SP Signal in Response to Water Flow in Fractured Crystalline Bedrock
Authors: Vinogradov Jan , Hidayat Miftah , Kumar Yogendra , Healy David , Comte Jean-Christophe
Published: March 2022

Previous field self-potential (SP) surveys have suggested this passive, non-intrusive geophysical method to be a powerful tool for characterizing subsurface flow of water in shallow fractured systems. However, to accurately interpret the measured signal requires knowledge of electrochemical properties of these settings. Despite the interest, the controls on the electric surface charge and the zeta potential of gneiss at conditions relevant to naturally fractured systems remain unreported. There are no published zeta potential measurements conducted in such systems at equilibrium, hence, the effects of composition, concentration and pressure remain unknown. This study reports zeta potential values measured in a fractured gneiss sample, obtained from the Lewisian complex in NW Scotland, and saturated with NaCl solutions of various concentrations, artificial seawater and artificial groundwater solutions under equilibrium conditions at confining pressures of 4 MPa and 7 MPa. The constituent minerals of the sample were identified using X-ray diffraction and linked to the concentration and composition dependence of the zeta potential. The results reported in this study demonstrate that the zeta potential of gneiss was unique and dissimilar to pure minerals such as quartz, calcite, mica or feldspar. Moreover, the measured zeta potentials suggest that divalent ions (Ca2+, Mg2+ and SO42−) acted as potential determining ions. The zeta potential was also found to be independent of salinity in the NaCl experiments, which is unusual for most reported data. Moreover, the impact of fracture aperture on the electrokinetic response was investigated and likely implications for characterization of fractured systems using SP analyzed. Our novel results are an essential first step for interpreting field SP signals and facilitate a way forward for characterization of water flow through fractured basement aquifers.