bluuebunny/crossref_metadata_2025 huggingface dataset:
The hows and whys of pre-eruptive magma migration before 2021 Cumbre Vieja eruption
Authors: Gonzalez Pablo J. , Charco María , Jiang Yu , Eff-Darwich Antonio , Sansosti Eugenio , Reale Diego , Morishita Yu , Munekane Hiroshi , Kobayashi Tomokazu
Published: March 2022

Reservoirs accumulate and evolve magma during decades to centuries under Canary Islands volcanoes. Finally, magma migrates towards the surface before eruptions. However, little is known about the pathways and mechanisms controlling this migration. Past low eruption recurrence rate and the fact that the most recent 2011-2012 El Hierro eruption was off-shore hampered us to fully understand the magma(s) migration process. During the 2021 Cumbre Vieja eruption eruptible magmas showed remarkable mobility during the preceding 8 days before the eruption on the 13th of September 2021. This magma migration was reflected as surface ground deformation and seismicity. We used satellite radar interferometry to track 1) the geometry of the active magmatic reservoirs, and 2) the dynamics of magma emplacement and migration. To further, speculate about the reasons for that geometry and dynamics. Hence, the 2021 Cumbre Vieja eruption represents a unique opportunity to learn more about the mechanisms that facilitate magma migration beneath these volcanoes, and compare it with similar basaltic volcanoes. Our work aims to contribute knowledge that will help hazard assessment and volcanic risk reduction. 
Rainfall Simulators – how plot scale affects results
Authors: Neumann Martin , Kavka Petr , Kubínová Romana , Tejkl Adam , Vrána Michal , Kubát Jan-František , Laburda Tomáš
Published: March 2022

Rainfall simulators (RS) are commonly used tools for soil erosion research under natural conditions. This research was focused on the plot scale effect in the formation of surface runoff and soil loss. Two surface conditions were tested - grass and bare soil. All experiments were performed in field conditions on undisturbed soil samples located on the experimental site Řisuty, where CTU has been performing experiments with rainfall simulators for many years. Three experiments were performed to investigate the formation of surface runoff depending on area size, surface type and precipitation intensity. These experiments were performed on a surface with grass cover and also on a plot of ​​cultivated bare soil. For the bare soil experiment, the area was prepared just prior to the experiment itself. The grass plots were left to develop naturally for 2 years after sowing. A large rainfall simulator with a maximal experimental area of 16 m2 (8 m length 2 m wide) was used for this experiment. Four plots with lengths of 1, 2, 4 and 8 m (with widths of 1 m) were placed under the RS. Soil moisture sensors were placed on the plot at various depths to monitor the evolution of soil moisture over time. For the plot with the grass cover, a rainfall with variable intensity over 75 minutes was used (rainfall intensities 40, 60, 90 mm/h). Two follow-up experiments were conducted on the plot with bare soil. Rainfall intensities were a constant 60 mm/h for 30 minutes after surface runoff starts. The second experiment started 15 minutes after the conclusion of the first one. This same methodology has been used in other, past, experiments with RS so our results are directly comparable to those previously conducted experiments. All results were recalculated to 1m2 and 1 minute intervals for comparison in addition to the cumulative values for each experiment.

Results from the plots with grassland showed significant differences between plots of different lengths. Experimental plots with bare soil provided higher variability in results on the plots in their natural moisture (dry condition), than those of the fully saturated samples. Results showed that the length of the plot is more important for soil loss than for surface runoff processes. The heterogeneity of the infiltration soil properties would play significant role on the experiment results.

This study has been supported by Grant Agency of the Czech Technical University in Prague, grant No. SGS20/156/OHK1/3T/11 and the Project QK1910029.
Hydrological Drought – 12 lessons learned in 12 minutes
Authors: Tallaksen Lena M.
Published: March 2022

In this presentation, I highlight key lessons learned following a career within drought research. From its start with focus on low flows in the 1990'ties to the definition of hydrological drought and its spatial and temporal patterns in more recent work - it has been an interesting and learning journey. A period that coincides with an increasing awareness of drought as a natural hazard at the local, regional and continental scale. It is also a period when the influence of climate change on the hydrological cycle, water resources and extremes, became prominent. Accordingly, time series could no longer be assumed stationary, which had been the basis for our hydrological training at the time, and the research focus shifted from more traditional hydrological analysis to the detection, attribution and projection of the climate change signal on hydrology. When analyzing drought and its wide range of impacts, it is important to distinguish between the different types of droughts, and when analyzing changes and trends, it is important to distinguish between natural variability and changes due to climate change or human interventions. How drought is defined and perceived in different sectors and regions across the world influences the choice of methodology and how the results are interpreted and communicated. The importance of drought terminology and awareness of the diversity in drought behavior - within and among regions - are aspects that have been essential throughout my research and that I will reflect upon in my talk.
Quantification of OH in quartz via infrared spectroscopy – new protocol for sample preparation and spectral analysis
Authors: Jaeger Dominik , Stalder Roland
Published: March 2022

Hydrous lattice point defects (OH defects) in quartz (SiO2) occur through coupled substitution of Si4+ with a trivalent cation (most commonly Al3+) and a hydroxyl group (OH-). These impurities can be used to investigate its host rock’s crystallization history and may therefore also serve as a tracer for sediment provenance analyses, but are also economically relevant (e.g., high purity quartz sources).

Transmission infrared (IR) spectroscopy has proven to be a very effective method to analyze OH defects down to concentrations of a few weight parts per million water equivalent. This technique, however, requires thin (100 to 200 µm), polished quartz wafers that are cut perpendicular to the crystallographic c-axis. Preparation of a statistically significant number (i.e. > 100) of grains using this approach is very time consuming and requires a skilled operator. Furthermore, IR spectral analysis so far does not follow a standardized protocol, possibly introducing individual biases and hampering reproducibility of as well as comparability between datasets.

In this work, we present a new, standardized procedure for sample preparation, measurement, and data analysis of OH defects in quartz. Sample preparation and IR measurements are significantly sped up and simplified and require relatively little specialized laboratory equipment. Additionally, our data analysis is performed largely automated and based on spectral deconvolution and generation of synthetic spectra before quantification, ensuring quick generation of reproducible results. This new protocol may therefore be another step towards making OH defect analysis accessible to a wider range of geoscientific fields.
Flooding of sandy beaches in a changing climate and the potential of nature based solution for impact mitigation.
Authors: Agulles Miguel , Jordà Gabriel
Published: March 2022

Sandy beaches have a paramount importance as natural barrier for coastal protection (Vousdoukas et al., 2020) and a valued socioeconomical asset for touristic activities (Enríquez & Bujosa Bestard, 2020). The unprecedented population expansion along with the sea level rise put the coastal areas under a high risk for the coming decades. An accurate estimate of the future evolution of sandy beaches is a key step for the development of effective adaptation strategies.

In this work, we estimate the potential loss of sandy beaches due to climate change under different scenarios of greenhouse gas (GHG) emissions. We focus on the Balearic Islands beaches as a case study representative of the Mediterranean sandy beaches. We combine a high-resolution nearshore total water level (TWL) with the detailed characteristics (area, granulometry and slope) of the 869 beaches of the Islands. TWL is obtained combining the contribution of mean sea level, storm surge and wave runup. In particular, a cost-effective methodology that combines numerical modelling and statistical techniques has been developed to  explicitly obtain wave runup on beaches.

An additional important point to be considered is that, in the Mediterranean Sea, seagrass meadows are commonly present at shallow depths (Marbà et al., 1996; Ruíz, Boudouresque, & Enríquez, 2009). This presence of vegetation plays a relevant role in the dissipation of the incident wave energy against the coast (Infantes et al., 2012) and, consequently, induces a reduction in the coastal flooding during extreme events.  So, in this work we consider the wave attenuation due to bottom flow and seagrass interaction in the wave propagation to the coast using a specific parametrization (Mendez & Losada, 2004).

The results show that the beach surface in the Balearic Island (~310ha) would be significantly reduced at mid and long term under the most likely scenarios of future GHG emissions (RCP4.5 and RCP8.5). In particular, at mid-century, around 35-45% of the beach area would permanently disappear under mean conditions, mainly due to the contribution of the mean sea level rise. Under storm conditions, the beach loss would increase up to 75-78% due to the wave runup effect. At the end of the century, around 55-65% of the beach area will be permanently flooded and around 85% under storm conditions. These results could be safely extrapolated to most regions in the Mediterranean as they share similar beach and hydrodynamic characteristics. Finally, some results on the potential of climate-based solutions to reduce the impact of storms will be presented.

 
Mediterranean climates during Dansgaard-Oechger cycles in the last glacial period
Authors: Turner Mark , Harrison Sandy P.
Published: March 2022

We investigate the impact of rapid climate changes during the Dansgaard-Oeschger cycles of the last glacial on the climate of the Mediterranean region. We reconstructed the temperature of the coldest and warmest months, growing season warmth, and plant-available moisture (MI) from 20 published pollen cores from Iberia to Iran, using frequency corrected tolerance-weighted weighted average partial least squares (fxTWA-PLS) method. We corrected the MI reconstructions to account for the direct physiological impact of changing CO2 levels on plant water-use efficiency. We found warm intervals – probable GIs - by identifying potential D-O warmings using their signature asymmetrical rise and fall. Cold climate intervals – considered as the most extreme expression of the GSs - were defined as periods when growing season warmth was below the long-term average value for each individual record.

Warm intervals are characterised by a decrease in moisture in the western Mediterranean compared to the preceding cold interval. Sites in the eastern Mediterranean show either no change in moisture between the two states or are characterised by a slight increase in moisture during the warm intervals compared to the cold intervals. There is also a marked west-east difference in temperature seasonality, with warmer intervals showing increased seasonality in the western and northwestern region compared to the eastern Mediterranean. The increased seasonality is largely driven by changes in summer temperature since the degree of winter warming during warm intervals is similar across the whole region. Changes in all of the bioclimatic variables between cold and warm intervals show a strong relationship with latitude: the latitudinal gradient is steeper in cold climates than in warm climates. The relative homogeneity of changes during the cold intervals is consistent with a more zonal circulation pattern than during warm intervals. This change in circulation patterns could help to explain the west-east patterns in the changes in moisture between cold and warm intervals.
Paleoclimatic reconstruction based on studying of soils of the short-term chronosequence, buried under different constructions in the big Boldyrevo kurgan
Authors: Sverchkova Alena , Khokhlova Olga
Published: March 2022

In 2019, kurgan 1 in the Boldyrevo IV kurgan cemetery in the Orenburg region, Russia was studied. The kurgan was built by the population of the Yamnaya culture of the Early Bronze Age (about 5500 years ago). Within the kurgan, four earthen structures built-in succession have been revealed. Under each of the kurgan structures, the buried soil has been studied. According to archaeological data, the kurgan was built over several decades; radiocarbon dating showed an interval of 300 years.

During the construction of the kurgan, the morphology and physicochemical properties of the soils and materials of the kurgan structures changed, namely, the content of organic matter decreased, while the content of carbonates, gypsum, exchangeable sodium in the composition of exchangeable bases and the value of magnetic susceptibility increased. It can be suggested that the studied interval of the kurgan building, like the entire early (Repino) stage of the Yamnaya culture, was characterized as more arid in comparison with the present.

Based on the micromorphological analysis and physicochemical properties of the materials of the kurgan structures and buried soils, it can be assumed that the monument was built from local soils using anthropogenic material. The construction technology consisted of rough kneading and tamping of raw sandy loam material with the addition of river silt, rare coal dust, and bones. For facing the ritual site around the main burial river silt was exclusively used.

Previously, in the study of short-term pedo-chrono-sequences under the structures of big kurgans of the Early Bronze Age of different ages in the Stavropol and Krasnodar Territories, it has been also compared the properties of paleosols and earthen structures. It allowed confirming the use of local soils in the construction of the monuments and carrying out paleoclimatic reconstruction. In addition, for all three studied big kurgans, a comparison was made of technical and technological approaches used by ancient builders for the construction of monumental facilities of earthen architecture.
Preliminary evaluation on soil erosion of alpine grassland fence project based on 137Cs and 210Pbex trace technique in the Northern Tibet
Authors: Liu Lin , Yuan Yong , Xiong Donghong , Zhang Xinbao
Published: March 2022

Studies on the soil erosion rate for aeolian grassland are crucial for accessing the effect of grassland restoration. Sandy land is widely distributed in the alpine grassland areas of Northern Tibet where the conflict between grass and livestock is severe. In order to effectively curb grassland degradation and reduce desertification, a series of protection projects have been implemented in that area. However, due to the lack of continuous observations in the field, the quantitative research on soil erosion process of alpine grassland has been relatively lagging behind, especially the impact of protection projects on soil erosion is difficult to evaluate. We compared soil erosion rates with and without fence protections through 137Cs and 210Pbex trace technique. We also combined soil erosion in sand source areas with vegetation and a near-source climbing dune to illustrate the effect of fence protection. The results showed that: (1) The area of fence protection reduced soil erosion, the soil erosion rates of 137Cs and 210Pbex in fenced protected area were 0.99 t·ha-1·yr-1 and -0.12 t·ha-1·yr-1, respectively, while those in free grazing areas were 3.68 t·ha-1·yr-1 and 0.46 t·ha-1·yr-1, respectively. (2) Fence protection significantly improved vegetation coverage, the average NDVI of fenced protected areas increased by 0.027 from 2011 to 2019, with a growth rate of 67.43%. The average NDVI in fenced protected areas in 2019 was 1.34 times that of free grazing areas. (3) After the implementation of the fence protection in the sand source area, the climbing dune had shown a development trend from mobile to semi-fixed dune from the foot of the climbing dune to the middle (about 100m distance). Therefore, our results highlighted that fence protection was the major reason for the mitigation of soil erosion in the alpine grasslands, which were the source of sand, and their climbing dunes. The results can be used as a reference for the evaluation of grassland restoration effectiveness on the Qinghai-Tibet Plateau.

Keywords: Soil erosion; Radionuclides; Fence protection; Alpine grassland; Climbing dune
Dust in brown dwarfs and extra-solar planets -3D Monte Carlo versus kinetic approach of TiO2 seed formation
Authors: Enghoff Martin Bødker , Köhn Christoph , Helling Christiane , Krog Dan , Gobrecht David , Sindel Jan Philip , Haynes Kirsty
Published: March 2022

Modelling the formation of cloud condensation nuclei is key for predicting cloud properties in and analyzing observational data from exoplanet and brown dwarf atmospheres. Based on kinetic results on cloud formation in exoplanets, we readdress the question about the formation of cloud condensation nuclei through a Monte Carlo approach. We tackle the formation of TiO2 clusters using a recently developed particle code in 3D. We initiate 1000 TiO2 molecules in a domain of 1 cm3 size. We trace individual particles and check after every time step whether particles collide and form larger clusters. We run simulations at temperatures between 500 K and 1500 K, with particle sticking probabilities between 0.1 and 1 and distinguish whether only monomers or all other clusters are allowed to stick to earlier formed clusters. We present the number densities, the size distributions and the formation rate of clusters of different size and compare our results with results from a kinetic approach.
Simulating the motion of individual clusters allows us to display the spatial distribution of all particles as well as to determine their mean and maximum size. We calculate the line opacities of (TiO2)N clusters and discuss their detectability through the James Webb Space Telescope or the upcoming Extremely Large Telescope. Our results present a first step towards a better understanding of the formation of cloud formation nuclei in extrasolar environments by comparing selected results from molecular dynamic simulations with a kinetic approach based on thermodynamic cluster data.
Plume-induced sinking of the intracontinental lithosphereas a fundamentally new mechanism of subduction initiation.
Authors: Cloetingh Sierd , Koptev Alexander , Kovacs Istvan , Gerya Taras , Beniest Anouk , Willingshofer Ernst , Ehlers Todd , Andric-Tomasevic Nevena , Botsyun Svetlana , Eizenhofer Paul , Francois Thomas , Beekman Fred
Published: March 2022

Although many different mechanisms for subduction initiation have been proposed, few of them are viable in terms of agreement with observations and reproducibility in numerical experiments. In particular, it has recently been demonstrated that intra-oceanic subduction triggered by an upwelling mantle plume could contribute greatly to the onset and functioning of plate tectonics in the early Earth and, to a lesser extent, in the modern Earth. In contrast, the onset of intracontinental subduction is still underestimated. Here we review 1) observations demonstrating the upwelling of hot mantle material flanked by sinking proto-slabs of the continental mantle lithosphere, and 2) previously published and new numerical models of plume-induced subduction initiation. Numerical modelling shows that under the condition of a sufficiently thick (> 100 km) continental plate, incipient down thrusting at the level of the lowermost lithospheric mantle can be triggered by plume anomalies with moderate temperatures and without significant strain and/or melt-induced weakening of the overlying rocks. This finding is in contrast to the requirements for plume-induced subduction initiation in oceanic or thin continental lithosphere. Consequently, plume-lithosphere interactions in the continental interior of Paleozoic-Proterozoic (Archean) platforms are the least demanding (and therefore potentially very common) mechanism for triggering subduction-like foundering in Phanerozoic Earth. Our findings are supported by a growing body of new geophysical data collected in a variety of intracontinental settings. A better understanding of the role of intracontinental mantle downthrusting and foundering in global plate tectonics and, in particular, in triggering "classic" oceanic-continental subduction will benefit from further detailed follow-up studies.
Mobile Evaporite Enhances Cycle of Physico-chemical Erosion in Badlands
Authors: Yang Ci-Jian , Chen Pei-Hao , Huang Jr-Chuang , Teng Tse-Yang
Published: March 2022

Erosion-induced weathering is significant control of Earth’s surface process, however, the impacts of extreme weather on chemical weathering dynamics are poorly understood. Badland landscapes formed with highly erodible, homogeneous substrates have the potential to respond measurably to the individual event on scales that are open to direct observation. Here, using the high temporal resolution of suspended sediment and riverine chemistry records in the badland basin in southwestern Taiwan, we assess the mineralogical, geochemical and grain-size composition features that can be used to quantify landscape response to erosion drivers. During the typhoon period, sodium adsorption ratio is covariant with suspended sediment concentration, which can be assigned to sodium-induced dissolution. Further, sodium and calcium of suspended sediment account for about 10 % of the mass loss in this event, and the current-induced dissipation may be responsible for it. Plus, water chemistry is dominated by silicate weathering at 18 ton/km2/day. We expect that the observation of physico-chemical reactions in badlands provides a deeper explanation of coupling of hillslope-channel landscape within erosional cycle.
Biogeochemical data assimilation in Copernicus Marine Services - status and future evolution
Authors: Samuelsen Annette , Teruzzi Anna
Published: March 2022

The Copernicus Marine Services is operationally producing forecasts and reanalysis of biogeochemical properties such as nutrients, phytoplankton biomass and carbon chemistry, in the ocean. A key part of these model products is the assimilation of observed biogeochemical properties. Both the methods for assimilating biogeochemical observations and the observation systems are constantly evolving. In this talk we will give an overview over the present capabilities of biogeochemical data assimilation within the Copernicus Marine Services. Presently, biogeochemical data assimilation services cover a range of spatial scales, from global ocean to regional seas, methods, and observations assimilated, which are based both on in situ and remote satellite measurements. We will also present the future evolution that is presently being prepared and researched within Copernicus Marine Services as well as in research projects, such as H2020 SEAMLESS. This includes exploring the prospect of assimilating new types of observations from BGC-Argo, gliders and from remote sensing.  We will also present plans for moving towards ensemble assimilation and, given the tight connection between physical and biogeochemical variability, steps towards simultaneously constraining physical and biogeochemical model properties.
Modelling of a retrofitting methodology to revive abandoned oil reservoirs for geothermal exploitation
Authors: Jia Lin , Li Kewen , Zhang Chi
Published: March 2022

Geothermal energy is considered as one of the renewable energy resources to meet the world's growing low-carbon energy demand. There are increasing number of oil wells to be abandoned and these wells could be potentially retrofitted to geothermal wells for sustainable purpose. There have been some studies and practices on retrofitting oil wells, but most of the existing retrofitting methods suffer from either low efficiency or high cost. In this study, we designed and modelled a novel retrofitting pattern to a single well featured with enhanced reservoir system (ERS). We established numerical models of ERS in abandoned oil reservoirs configured with a vertical well. We simulated the effects of reservoir initial oil saturation, thickness, permeability and different ERS designs on the production temperature and output power after 50 years. We found these effects have positive feedback on the production temperature and output power. In addition, we also modeled the temperature effect on oil-gas-water relative permeability as it would highly affect the oil viscosity and mobility in the oil reservoir. Moreover, through sensitive analyses of this retrofitted single well and the traditional doublet geothermal well, we found the retrofitted single well in our study could be as high as that from doublet geothermal well, implying that one single abandoned oil well could work either for direct use or power generation with economic yield but little retrofitting investment. Lessons learned in this study might also be applied to other geothermal scenarios, such as enhanced geothermal system.
A global perspective on Bromine monoxide composition in volcanic plumes derived from S5-P/TROPOMI
Authors: Warnach Simon , Borger Christian , Bobrowski Nicole , Sihler Holger , Schöne Moritz , Beirle Steffen , Platt Ulrich , Wagner Thomas
Published: March 2022

Bromine monoxide (BrO) is a halogen radical capable of influencing atmospheric chemical processes, in particular the abundance of ozone, e. g. in the polar boundary layer and above salt lakes, in the stratosphere as well as in volcanic plumes. Furthermore, the molar bromine to sulphur ratio in volcanic gas emissions is a proxy for the magmatic composition of a volcano and potentially an eruption forecast parameter.

To monitor volcanic activities on global scale, satellite measurements provide invaluable information. For these purposes, the TROPOspheric Monitoring Instrument (TROPOMI) onboard ESA’s S5-P satellite is particularly interesting: its high spatial resolution of up to 3.5x5.5km2 and daily global coverage offer great potential to detect BrO and its corresponding ratio with sulphur dioxide (BrO/SO2) even during minor eruptions and for continuous passive degassing volcanoes.

Here, we present a global overview of BrO/SO2 molar ratios in volcanic plumes derived from a systematic long-term investigation covering four years (Januar 2018 to December 2021) of TROPOMI data.

We retrieved column densities of BrO and SO2 using Differential Optical Absorption Spectroscopy (DOAS) and calculated mean BrO/SO2 molar ratios for various volcanoes. The calculated BrO/SO2 molar ratios differ strongly between different volcanoes, but also between measurements at one volcano at different points in time, ranging from several 10-5 up to several 10-4. In our four-year study of S5P/TROPOMI data we successfully recorded elevated BrO column densities at 506 volcanic events. We were able to derive significant BrO/SO2 ratios at 26 different volcanoes on 378 occasions, thus adding an important volcanic parameter to these volcanoes.

In addition, this large data set of events allows to deduce time-series of several very active volcanoes, such as Mount Etna, Italy and Ambrym, Vanuatu.
Removal of false alarms from solar wind predictions
Authors: Dalya Zsuzsanna , Opitz Andrea
Published: March 2022

Solar wind propagation models using in situ plasma observations as input can be improved by removing the signatures of Interplanetary Coronal Mass Ejections (ICMEs) from the input data. ICMEs are sporadic events that propagate in a given direction, hence their signatures in the plasma data should not be extrapolated to other heliocentric longitudes. As a result, in order to improve the prediction accuracy these should be filtered out. We create dedicated ICME lists providing the exact start and end times of ICMEs to numerous space probes such as ACE, STEREO A&B, SOHO, WIND, SolO, PSP, DSCOVER, VEX, MEX, Rosetta, BepiColombo, MAVEN and Messenger. We provide solar wind plasma and magnetic field predictions to any inner heliospheric position applying the ICME filter on the input dataset this way eliminating false alarms such as false ICME signature forecasts. Our corrected predictions contribute to the investigation of the background solar wind and related fields.
Statistical analysis of multi-annual time series of atmospheric mineral dust content in the Sahel. 
Authors: Lhotte Alban , Marticorena Beatrice , Coman Adriana , Bergametti Gilles , Rajot Jean Louis , Féron Anais , Gaimoz Cécile
Published: March 2022

Mineral dust has radiative and biogeochemical impacts, affects human health and soil fertility. The mineral dust cycle, i.e., dust emission, transport and deposition depends on meteorological parameters, in particular surface wind speed and precipitation. Climate change has lead to measurable change in surface temperature and precipitation regimes in the Sahel (e.g., Panthou et al., 2018) and is also expected to modify the surface winds that controls dust emissions and transport. 

Since 2006, mineral dust is monitored in the Sahel by the stations of the INDAAF network (https://indaaf.obs-mip.fr/). We used the PM10 surface concentrations and the Aerosol Optical Depth (AOD) from the AERONET network measured in Cinzana (Mali) and Banizoumbou (Niger) to detect possible changes in the Sahelian atmospheric dust content. The Angstrom exponent is used to select situations where mineral dust is the dominant contributor to the AOD. PM10 concentrations and AOD are significantly correlated but have distinct seasonal cycles, with a ratio PM10/AOD peaking in August.

No clear trend on the annual and seasonal mean concentrations or AODs has been identified. When subtracting the mean seasonal cycle to the monthly median PM10 concentration we observe a slight decrease of the residuals  in Cinzana (Mali) but no trend in the AOD. No correlation was found between the AOD or the PM10 concentrations and the North Atlantic Oscillation Index but the PM10 concentration tends to increase with the Sahelian drought index.  For most of the years, the PM10 concentrations and AODs are lower when the maximum of the vegetation cover of the previous year (represented by satellite Normalized Vegetation Index) is higher. This may reflect the protective effect of the dry vegetation residues on dust emission. These results suggest that, for the measurement period (2006-2019), the variability of the dust content is mainly due to the seasonal cycle and that the year to year variability is so large that no trends can be detected. Longer time series, with a better temporal sampling, seem to be necessary to have a chance to detect a significant change.
A new model for the evolution of oceanic transform faults based on 3D PSDM Seismic observations from São Tomé and Príncipe, eastern Gulf of Guinea.
Authors: Heine Christian , Thomas Myron , van Itterbeeck Jimmy , Ostanin Ilya , Seregin Andrey , Spaak Michael , Morales Tamara , Oude Essink Tess
Published: March 2022

Oceanic Transform faults are one of the three major tectonic plate boundaries and yet their evolution and deformational mechanism is not well understood. They are broadly considered to be dominated by strike-slip displacement along simple planar vertical faults and to be conservative in nature with no magmatic addition. Observations from Pre-Stack depth-migrated (PSDM) 3D seismic of Cretaceous-aged transforms in the eastern Gulf of Guinea allow complex internal architectures to be described, including crustal scale detachments and rotated packages of volcanics.

These insights demonstrate additional complexity previously only predicted in numerical simulations of spreading ridge-transform interaction, namely intra-transform extension at a high angle to the spreading orientation, and the addition of significant extrusive volcanic material. In the study area of São Tomé and Príncipe, several Oceanic Fracture Zones (OFZ) are identified, consisting of a broad deformational zones that can be described from top to base crust. OFZ scarps are observed to connect at depth with zones of low angle reflectivity which dip into the OFZ and perpendicular to the spreading orientation. At depth they detach onto the Moho below, necking the adjacent crust along the length of the OFZ in the manner of extensional shear zones. Thickly stacked and tilted reflectors, interpreted as extrusive lava flows, are common above the shear zones and infill up to 75% of the crustal thickness. The entire OFZ stratigraphy is overlain and sealed by late-stage lavas that are continuous from the abyssal hills of the trailing spreading ridge. This constrains a process of oblique extension at a high angle to the spreading orientation along a low angle shear zone which also acts as a conduit for decompression related melt.

We demonstrate that transforms in São Tomé and Príncipe were both non-conservative and not a simple strike slip fault zone, contradicting the current understanding of modern systems. This style of deformation has similarities with anomalously deep and smooth nodal basins which form at slow spreading inside-corner crust. Our model adds strong observational constraints to complement recent numerical models that predict oblique extension within transform zones.
Analysis of seasonal inorganic chemistry of aerosols with source attribution in a peri-urban landscape in lower Gangetic basin
Authors: Barik Gunadhar
Published: March 2022

Aerosols play a significant role in Indian seasonal variation. In this study, inorganic chemistry of the atmospheric aerosols including the gaseous pollutants, such as SO2, NO2, and NH3, were analyzed during seasonal variation (pre-monsoon, monsoon, post-monsoon, and winter seasons) in a peri-urban location in the lower Gangetic basin (LGP). The aerosol inorganic chemistry was analyzed for the surface concentration of NO3, SO4, and NH4. The aerosol samples including gaseous compounds were collected using a high-volume sampler (HVS) (passive), and through dry deposition (active) on to a petri dish. The samples were collected from March 2019 to February 2020, with a sampling frequency of twice a week. The average dust flux was found around 9.85 and 15.49 ug cm-2h-1 in pre-monsoon, 5.298 and 5.432 ug cm-2h-1 in monsoon, 12.04 and 16.15 ug cm-2h-1 in post-monsoon and 12.28 and 16.84 ug cm-2h-1 in winter season through active and passive methods, correspondingly. The estimated SO2, NO2, and NH3 were 14.32, 9.22, and 23.49 ug m-3 in pre-monsoon, 18.335, 8.277, and 22.855 ug m-3 in monsoon, 29.83, 5.28 and 24.85 ug m-3 in post-monsoon and 22.56, 10.68 and 22.46 ug m-3 in winter season respectively. The estimated SO4, NO3 and NH4 were 0.07, 0.04 and 0.1 µg cm-2 in pre-monsoon, 0.1, 0.04, and 0.06 µg cm-2 in monsoon, 0.09, 0.04, and 0.07 µg cm-2 in post-monsoon and 0.08, 0.02 and 0.07 in winter season, respectively. The correlations of the gaseous components with components derived from the aerosol surface remain weak, however positive in most of the seasons, suggesting no significant uptake of the gaseous pollutant by the aerosols. The linear modeling of these chemical species with the weather parameters (temperature, RH, and wind speed) including AOD, derived from MODIS, showed dynamic relationships implying a significant modification of atmospheric properties moderated by the weather parameters. The HYSPLIT model of 3 days’ back trajectory and PSCF model indicated during pre-monsoon, post-monsoon, and winter seasons 60-80% cluster and aerosol were originated from the IGP, east-coast, and eastern part of India, however during monsoons season 70-80% cluster and aerosol were originated from the Arabian sea and the Bay of Bengal, suggesting the nearby dominated local sources of these aerosol components.
Disturbance Storm Time (Dst) index estimation using deep learning applied to Swarm satellite data
Authors: Cianchini Gianfranco , Piscini Alessandro , De Santis Angelo , Arquero Campuzano Saioa
Published: March 2022

Computed from the intensity of the globally symmetrical equatorial electrojet (Ring Current) measured by a series of near-equatorial geomagnetic observatories, the Dst (Disturbance Storm Time) is an hourly index of magnetic activity. To give the estimation of the Dst index through the magnetic data measured by the Swarm three-satellite mission, we selected and trained an Artificial Neural Network (ANN). From November 2014 to December 2019, we collected a big Swarm magnetic dataset, confined in space to three very narrow belts of low-to-mid latitude, to better resemble the geographic distribution of the four geomagnetic observatories used to estimate at ground Dst. We also extended the analysis to mid latitude locations to increase the number of satellite samples. By using a Deep Learning architecture and based on its performance, we selected the best topology and trained the network testing its modelling capabilities. The outcomes show that the ANN is able to give a reliable fast estimation of the Dst index directly from Swarm satellite magnetic data, especially during magnetically disturbed periods.
The critical point and the supercritical regime of MgO
Authors: Bögels Tim , Caracas Razvan
Published: March 2022

The position of the critical point determines the top of the liquid-vapor coexistence dome, and is a physical parameter of fundamental importance in the study of high-energy shocks, including those associated with large planetary impacts. For most major planetary materials, like oxides and silicates, the estimated position of the critical point is below 1 g/cm3 at temperatures above 5000 K. Here we compute the position of the critical point of one of the most ubiquitous materials: MgO. For this, we perform first-principles molecular dynamics simulations. We find the critical density to be in the 0.4 - 0.6 g/cm3 range and the critical temperature in the 6500 - 7000 K range. We investigate in detail the behavior of MgO in the subcritical and supercritical regimes and provide insight into the structure and chemical speciation. We see a change in Mg-O speciation towards lower degrees of coordination as the temperature is increased from 4000 K to 10000 K. This change in speciation is less pronounced at higher densities. We observe the liquid-gas separation in nucleating nano-bubbles at densities below the liquid spinodal. The majority of the chemical species forming the incipient gas-phase consist of isolated Mg and O atoms and some MgO and O2 molecules. We find that the ionization state of the atoms in the liquid phase is close to the nominal charge, but it almost vanishes close to the liquid-gas boundary and in the gas phase, which is consequently largely atomic.

 

This research was supported by the European Research Council under EU Horizon 2020 research and innovation program (grant agreement 681818–IMPACT to RC). This research was performed by access to supercomputing facilities via eDARI stl2816 grants, PRACE RA4947 grant, Uninet2 NN9697K grant.
Deep learning for extreme wind speed prediction with CyGNSSnet
Authors: Arnold Caroline , Zhao Daixin , Xiao Tianqi , Mou Lichao , Asgarimehr Milad
Published: March 2022

The CyGNSS (Cyclone Global Navigation Satellite System) satellite system measures GNSS signals reflected off the Earth’s surface. A global ocean wind speed dataset is derived, which fills a gap in Earth observation data and can improve cyclone forecasting. We proposed CyGNSSnet(1), a deep learning model for predicting wind speed from CyGNSS observables, and found an improved performance of 29% compared to the current operational model. However, the prediction of extreme winds remained challenging: For wind speeds exceeding 12 m/s, the operational model outperformed CyGNSSnet.

Here, we explore methods to improve the performance of CyGNSSnet at high wind speeds. We introduce a hierarchical model that combines specialized CyGNSSnet instances trained in different wind speed regimes with a classifier to select an instance. In addition, we explore strategies to improve the wind speed predictions by emphasizing extreme values in training, and we discuss the potentials and shortcomings of the approaches.

(1) Asgarimehr, M., Arnold, C., Weigel, T., Ruf, C. & Wickert, J. GNSS reflectometry global ocean wind speed using deep learning: Development and assessment of CyGNSSnet. Remote Sensing of Environment 269, 112801 (2022).
Evolution of a clastic source-to-sink system through the Permian-Triassic transition: Provenance and petrography of the Havert Formation on Finnmark Platform, Barents Sea, Norway
Authors: Kling Melanie , Sirevaag Hallgeir , Eide Christian Haug
Published: March 2022

The onset of the Siberian Traps Large Igneous Province at the Permian–Triassic transition significantly affected climate and depositional environments across the world. Known long term consequences of this event are (I) global warming, (II) increased continental weathering, (III) oceanic stagnation and acidification and (IV) mass extinction. These effects have the potential to strongly alter signals from source-to-sink systems in terms of petrography, sediment volumes and geochemistry. On the Finnmark Platform, a shift in provenance from a southern source to an eastern source during the middle Triassic is known. However, the impact of the environmental changes at the Permian-Triassic transition have so far not been investigated. The Barents Sea Basin contains a continuous record of sediments deposited before, during and after the Permian-Triassic event. The interval is present in several exploration wells, which show the transition in individual depositional environments. Therefore, it serves as an excellent area to investigate the response of source-to-sink systems to such extreme climatic changes.

The goal of this project is to investigate how the Triassic climatic changes were expressed in source-to-sink systems, mainly using techniques such as provenance, facies analysis, petrography, and sediment volumes. Herein we present preliminary provenance and petrography results mainly from Induan-aged sandstones and clasts from the Havert Formation. On the Finnmark Platform, upper Permian spiculate mudstones, limestones, and sparse sandstones are overlain by Lower Triassic mudstones and interbedded sandstones, which deposited as turbidites and prograding deltas. In order to determine how the signal from the catchment changed in relation to the great climatic changes, it is of high importance to examine changes within provenance and sediment volumes across the Permian-Triassic transition.
Dealing with a PFAS-polluted aquifer: from modelling to in-situ remediation treatment
Authors: Bosch Carme , Fernandez-Rojo Lidia , Perez-Estrada Leonidas , Plà-Castellana Mireia , Devau Nicolas , Groot Hans , Marsman Annemieke , Farré Marinel·la , López de Alda Miren , Matamoros Víctor , de Buen Hector , Mora Ricard
Published: March 2022

PFAS (per- and polyfluoroalkyl substances) are anthropogenic pollutants which are persistent in the environment and toxic for the human health. The H2020 PROMISCES project (GA-101036449), funded through the European Green Deal call, aims to understand the origins, routes and fates of these pollutants with the goal of moving forward a zero-pollution circular economy. One of the considered routes is the soil-groundwater continuum. Here, this route is studied within a case study located in Tordera aquifer (Spain) affected by PFAS from aqueous film forming foams used in fire-fighting activities.

Modelling the fate and transport of PFAS in a real aquifer is one of the objectives of PROMISCES. The proposed model train will be built by coupling a 1D-2D variably-saturated flow reactive model, developed using a modified version of HYDRUS/PHREEQC, for the vadose zone, and a 2D-fully saturated flow and reactive transport model based on Modflow/MT3D software, for the saturated zone. Thus, it will provide information about the fluxes from contaminated soil to groundwater in the investigated case study. The models produced within PROMISCES can be used to predict the PFAS plume evolution in similar polluted aquifers.

Another goal of the project is to develop novel remediation technologies to degrade PFAS in groundwater. Alternative oxidation processes (e.g. persulfate activated with Fe(II), H2O2, or (n)ZVI) will be tested at bench-scale. Based on degradation rate, by-product formation, reagent consumption and associated costs, the most efficient treatment will be chosen for up-scaling and applied within the investigated polluted aquifer.

In this conference, it will be presented how the PROMISCES project address the PFAS-polluted aquifer problem in a dedicated site with modelling tools and with the implementation of in situ advanced oxidation treatments to depollute groundwater.
Antarctic sub-shelf melt during the present and the last interglacial and its impact on ice sheet dynamics
Authors: Menthon Maxence , Bakker Pepijn , Quiquet Aurélien , Roche Didier
Published: March 2022

The response of ice sheets to climate changes can be diverse and complex. The amplitude, speed and irreversibility of the melting of the ice sheets due to current anthropogenic emissions remain largely uncertain after 2100. Being able to reconstruct the evolution of the ice sheets during the past climate changes is a possible approach to constrain their future evolution in time scales further than the end of the century.

Here we aim to reconstruct the evolution of the Antarctic ice sheet during the Last Interglacial (LIG, ~ 130 to 115 kyr BP). The LIG was 0.5 to 1˚C warmer than the pre-industrial era with a sea-level between 6 to 9 m above present level. In other words, the Antarctic ice sheet during the LIG can be considered as an analogue to its future evolution. Moreover, it is the interglacial on which we have the most geological records to compare with simulation results.

Knowing that the oceanic forcing is the main driver of the Antarctic ice sheet retreat, we introduced the sub-shelf melt module PICO (Reese et al. 2018) in the ice sheet model (GRISLI, Quiquet et al. 2018) in order to physically compute the melt. We use outputs from the Earth Sytem Model (iLOVECLIM, Roche et al. 2014) to force idealized experiments. Several time periods will be covered: present-day, last glacial maximum and LIG. This work is a first step towards a fully coupled iLOVECLIM-GRISLI-PICO simulation to explicitly take into account the ice sheet climate - interactions in a physical way in simulations of the Antarctic ice sheet during the LIG and future centuries.