bluuebunny/crossref_metadata_2025 huggingface dataset:
Models of sedimentary fans and alluvial plains and how they propagate sedimentary, climatic and tectonic signals
Authors: Braun Jean
Published: March 2022

The large-scale and long-term transport and deposition of sediment is commonly represented by one of two reduced-complexity models, namely the transport limited (or T-L) model or the under-capacity (or ξ−q) model more recently developed by Davy and Lague (2009). Using both models, I investigated the behavior of a sedimentary continental system fed by a fixed sedimentary flux from a nearby active orogen though which sediments transit to a fixed base level representing a large river, a lake or an ocean.

Firstly, I will show that the two models share the same steady-state solution, for which a simple 1D analytical solution exists that reproduces the major features of many orogenic sedimentary systems: a steep fan adjacent to the mountain front that connects to a shallower alluvial plain. The resulting fan geometry obeys basic observational constraints on fan size and slope with respect to the upstream drainage area, A0. I will also show that the solution is strongly dependent on the size of the system, L, in comparison to a distance L0 that is determined by the size of A0. This gives rise to two fundamentally different types of sedimentary systems: constrained systems where L < L0 and open systems where L > L0. Constrained systems contain only a steep, conical fan that connects directly to the base level, whereas open systems are made of a steep fan connecting to a broad, low slope alluvial plain.

Secondly, I will present simple expressions that show the dependence of the system response time on the system characteristics, such as its length, the size of the upstream catchment area, the amplitude of the incoming sedimentary flux and the respective rate parameters (diffusivity or erodibility) for each of the two models. The ξ−q model predicts significantly longer response times, which I relate to its greater efficiency at propagating signals through its entire length. I will also demonstrate that, although the manner in which signals propagates through the sedimentary system differs greatly between the two models, they both predict that perturbations that last longer than the response time of the system can be recorded in the stratigraphy of the sedimentary system and in particular of the fan.  Interestingly, the ξ−q model predicts that all perturbations (regardless of their period) in incoming sedimentary flux will be transmitted through the system whereas the T-L model predicts that rapid perturbations cannot. I will finally discuss why and under which conditions these differences are important and propose observational ways to determine which of the two models is most appropriate to represent natural systems.

Reference: Davy P. and Lague D., JGR-Earth Surface, 2009.
A complete meteo-hydrological chain to support early warning systems from weather scenarios to flooded areas: the Apollo medicane use case
Authors: Lagasio Martina , Fagugli Giacomo , Ferraris Luca , Fiori Elisabetta , Gabellani Simone , Masi Rocco , Mazzarella Vincenzo , Milelli Massimo , Parodi Andrea , Pignone Flavio , Puca Silvia , Pulvirenti Luca , Silvestro Francesco , Squicciarino Giuseppe , Parodi Antonio
Published: March 2022

An intense Mediterranean hurricane (medicane Apollo) hit many countries during the last week of October 2021. Up to 7 people died because of the floods caused by the cyclone in Tunisia, Algeria, Malta and Italy. Apollo persisted over the same Mediterranean area from 24 October to 1 November 2021 producing flash-flood and flood episodes with very intense rainfall events, especially over eastern Sicily and Calabria on 25-26 October 2021. CIMA Foundation operated in real-time with a complete forecasting chain to predict both the Apollo medicane weather evolution and its hydrological and hydraulic impacts. The work provides support to the Italian Civil Protection Department early warning activities and in the framework of the H2020 LEXIS and E-SHAPE projects. The complete meteo-hydrological forecasting chain is composed by the cloud-resolving WRF model assimilating radar data and in situ weather stations (WRF-3DVAR), the fully distributed hydrological model Continuum, the automatic system for water detection (AUTOWADE), and the hydraulic model TELEMAC-2D. This work presents the forecasting performances of each model involved in the CIMA meteo-hydrological chain, with focus on both very short-range temporal scales (up to 6 hours ahead) and short-range forecasts (up to 48 hours ahead). The WRF-3DVAR model results showed very good predictive capability of the most intense rainfall events in terms of timing and location over Catania and Siracusa provinces in Sicily. Thus, enabling also very accurate discharge peaks and timing predictions for the creeks hydrological network peculiar of eastern Sicily. Starting from the WRF-3DVAR model predictions, the daily AUTOWADE tool run using Sentnel-1 (S1) data, was anticipated with respect to the scheduled timing to quickly produce a flood map (S1 acquisition performed on 25 October 2021 at 05UTC, flood map produced on the same day at 13UTC). Furthermore, an ad hoc tasking of the COSMO-SkyMed satellite constellation was performed, again based on the on the WRF-3DVAR predictions, to overcome the S1 data latency on eastern Sicily during the period 26-30 October 2021. Finally, the resulting automated operational mapping of floods and inland waters was integrated with the subsequent execution of the hydraulic model TELEMAC. Due to the probable frequency increase of such extreme events (in light of the ongoing climate change), the application of a complete meteo-hydrological chain presented in this work can pave the way for future applications in early warning activities in the Mediterranean areas.
Detection of rockfall activity due to rock freezing and thawing by electronic geotechnical sensors in Slovenia
Authors: Jemec Auflič Mateja , Šegina Ela , Peternel Tina , Zupan Matija , Vihtelič Andrej
Published: March 2022

Rockfalls are caused by preparatory processes (weathering and crack propagation) that gradually degrade bedrock and by triggering g processes (freeze-thaw activity, precipitation events, earthquakes, snow avalanches, animals, or anthropogenic activities) that eventually release a rock block. Both processes are controlled by several factors representing the internal (geology), external (meteorology), and surface and near-surface conditions (topography, vegetation, snow cover, thermal conditions, chemical weathering, and hydrology) of the bedrock. In this paper, electronic geotechnical monitoring is developed to detect the rockfall activity due to rock freezing and thawing on two separate steep cliffs composed of igneous and carbonate rocks in the eastern part of Slovenia. The monitoring programme includes automatic recordings of rock temperatures and meteorological influencing factors (air temperature, humidity, and precipitation), tiltmeters, kit for measuring rock stress and deformability, laser distance meters, and crackmeters. During the 2020 field investigation, cracks and discontinuities were mapped and Rock Mass Rating (RMR) was estimated. The Hoek-Brown Geological Strength Index was determined to qualitatively assess surface conditions in inaccessible areas using visual assessments of tectonic ruptured walls. We will present the first preliminary results of the parameters monitored for 10 months, which will help interpret rockfall activity and identify freeze-thaw cycles.

 

Acknowledgement:  The research was funded by the Slovenian Research Agency (Research project J1-3024). The electronic geotechnical sensors were founded by Project »Development of research infrastructure for the international competitiveness of the Slovenian RRI Space – RI-SI-EPOS« The operation is co-financed by the Republic of Slovenia, Ministry of Education, Science and Sport and the European Union from the European Regional Development Fund.
Comparing extreme precipitation between data from rain gauges, weather radar and high-resolution climate models
Authors: Arnbjerg-Nielsen Karsten , Thomassen Emma Dybro , Thorndahl Søren Liedtke , Andersen Christoffer Bang , Gregersen Ida Bülow , Sørup Hjalte Jomo Danielsen
Published: March 2022

The representation of extreme precipitation at small spatio-temporal scales is of major importance in urban hydrology. The present study compares observations from tipping bucket gauges and a C-band radar to two sets of re-analysis climate model output data for a historic period of 14 years where there is full spatial and temporal overlap between datasets. The reanalysis data are based on models with different parametrizations and spatio-temporal resolutions, one being a “convective-permitting” model while the other uses a convective parametrization scheme to account for convective rainfall. The study focuses on an area of approximately 100 by 150 km.

The datasets are compared with respect to seasonality of occurrence, intensity levels and spatial structure of the extreme events. All datasets have similar seasonal distributions, and comparable intensity levels. There are, however, clear differences in the spatial correlation structure of the extremes. Seemingly, the radar data is best representation of a “real” spatial structure for extreme precipitation, even though challenges appear in data when moving far from the physical radar. The spatial correlation in point observations is a valid representation of the spatial structure of extreme precipitation. The convective-permitting climate model seem to represent the spatial structure of extreme precipitation much more realistically, compared to the coarser convective parameterized model. However, improvement could be made for the shortest durations and smallest spatial scales.
A revised chronology of the Ripoll Basin (NE Spain). Towards an integrated chronostratigraphy of the south-Pyrenean Foreland.
Authors: Juvany Philémon , Garcés Miguel , Lopez Blanco Miguel , Martín Closas Carles , Beamud Amorós Elisabet , Bekkevold Susanna Emilia
Published: March 2022

Although the Cenozoic stratigraphy has been widely studied in the Pyrenees, there are still strategic locations lacking a robust dating. Assessing a detailed chronostratigraphic framework is crucial to understand the processes driving the basin evolution and constitute an essential part of the Source to Sink approach. The Early-Eocene represents a crucial stage of the South Pyrenean foreland basin evolution, during which the emplacement of the Southern Pyrenean thrust units lead to basin partitioning and a diversification of the sediment routing systems. To understand sediment transfer across the Eastern and Central South Pyrenean foreland, fine timelines are needed to assess interbasinal correlations and to decipher the linkage between adjacent sedimentary systems and sub-basins.  Here we applied magnetostratigraphy to the 5km thick sedimentary succession that filled the Ripoll basin, as part of the subsiding south-pyrenean trough, aiming at improving the reliability of the dating achieved by earlier studies (Burbank et al., 1992). An increased sampling resolution of the targeted sections allowed a more refined characterization of the local magnetostratigraphy. Integration with marine (shallow-benthic foraminefera) and continental (charophytes, mammals) biostratigraphic data provided a preferred correlation with the Geomagnetic Polarity Timescale (GPTS) that challenges earlier studies. Implications of the new age model for the thrust-belt kinematics, subsidence and the sedimentary evolution of the basin are discussed.

References :

Burbank, D. W., Puigdefàbregas, C., & Muñoz, J. A. (1992). The chronology of the Eocene tectonic and stratigraphic development of the eastern Pyrenean foreland basin, northeast Spain. Geological Society of America Bulletin,104, 1101–1120.
Terrestrial and Atmospheric Controls on Surface Energy Partitioning and Evaporative Fraction Regimes Over the Tibetan Plateau in the Growing Season
Authors: Yang Chenyi
Published: March 2022

Land-atmosphere interactions are an essential component of the climate system. However, no detailed description of the underlying effects of the surface forcing of the atmosphere has been established. In this study, GLEAM, MODIS, and ERA5 were the input set of multiple analysis algorithms, "segmentation" was the core idea of the analysis method. The study area is segmented into six surface response functional groups, and the multidimensional evaporation regime function was segmented into piecewise functions controlled by segment authoritative variables. Inspired by the surface heat balance equation and moisture-limited, energy-limited evaporation regimes, we chose soil moisture content and the net radiation flux to represent the moisture and energy status, respectively, and chose the leaf area index (LAI) to characterize the vegetation cover to investigate the primary effects of surface parameters on the energy partitioning of the land surface and evaporative regime. The results show that though a coupling strength 1.8 times greater was obtained when the LAI was used as the explanatory variable instead of soil moisture, soil moisture was still the highest explanatory variable in the regression tree analysis. This is consistent with the essence of the evaporative fraction and indicates that water should be the most fundamental explanatory variable. The evaporative regime was subdivided from two phases into five phases according to the effects such as water extraction by vegetation, photosynthesis, soil shading, and roughness changes, each with an authoritative explanatory variable.
Multivariate Approach Reveals a Higher Likelihood of Compound Warm-wet Spells in Urban India
Authors: Pradhan Sucheta , Ganguli Poulomi
Published: March 2022

Floods, heatwaves, and humid heat stress often lead to extreme consequences that threaten human health, economic stability, and resilience to natural and built environments. According to the Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change, heat stress has steadily increased over the Indian subcontinent. Along with the increase in heat stress, the frequency of heavy precipitation and flood events has grown over multiple locations across South Asia. Most studies assessed trends in heatwave and dry spells over South Asia, emphasizing sensible heat (dry bulb temperature) only and mostly performed attribution and risk analyses considering one driver at a time. A few studies have presented a climate-informed pluvial flood risk model accounting for sensible heat flux, neglecting the influence of humidity. However, very few studies have explored the compound role of humid heat stress followed by extreme precipitation within a limited time window. Here we show the concurrence of humid heat stress (i.e., heatwave compounded by humidity, hereafter HHS) and peak rain events in major urban locations across climatologically disparate monsoon sub-regions of India using ground-based observations. The observational evidence reveals the cities across the western half of the country show positive dependence between humid heat stress and extreme precipitation, whereas those located over the eastern half showed negative correlations. Our findings suggest the role of moisture transport in amplifying precipitation intensity preconditioned by HHS. Further, our joint hazard assessment model identifies potential hotspots where the humid heat stress is likely to intensify the precipitation extremes and consequently have extreme impacts of consecutive disasters (close succession of heatwave and heavy rainfall) over densely populated urban locations. The derived insights provide a clear rationale for assessing heatwave-induced pluvial flood response in a multi-hazard framework, which has implications for climate adaptations, ensuring science-policy cooperation.  
Physiological responses of soil microorganisms to weeks, years, and decades of soil warming
Authors: Söllinger Andrea , Séneca Joana , Dahl Mathilde Borg , Motleleng Liabo L. , Prommer Judith , Verbruggen Erik , Sigurdsson Bjarni D. , Janssens Ivan , Peñuelas Josep , Urich Tim , Richter Andreas , Tveit Alexander T.
Published: March 2022

How soil microorganisms respond to global warming is a key question in microbial ecology and eminently relevant for soil ecosystems, the terrestrial carbon cycle, and the climate system. However, physiological responses of soil microorganisms – key to infer future soil-climate feedbacks – are poorly understood.

We here make use of the longest lasting in situ soil warming experiment worldwide, ForHot, in which an Icelandic subarctic grassland site has been exposed to natural geothermal soil warming for more than 50 years. Using a metatranscriptomics approach, allowing the comprehensive study of the entire active soil microbial community and their functions by analysing expressed genes, we revealed key physiological responses of soil Bacteria to medium- (8 years) and long-term (>50 years) soil warming of +6 °C.

Irrespective of the duration of warming, we observed a community-wide upregulation of central (carbohydrate) metabolisms and cell replication and a downregulation of the bacterial protein biosynthesis machinery in the warmed soils. This coincided with a decrease of microbial biomass, a decrease of total and biomass-specific RNA content, and lower soil substrate concentrations in the warmed soils. We conclude that higher biochemical reaction rates, caused by higher temperatures, allow soil Bacteria to reduce their cellular number of ribosomes, the macromolecular complexes carrying out protein biosynthesis. To further test this we revisited the site and conducted a short-term warming experiment (6 weeks, +6 °C), which supported our conclusion.

The downregulation of the protein biosynthesis machinery (i.e., the reduction of ribosomes) liberates energy and matter, leading to a resource re-allocation, and allows soil Bacteria to maintain high metabolic activities and cell division rates even after decades of warming.
Simulating the land-atmosphere exchange over mountainous terrain
Authors: Lehner Manuela , Simonet Gaspard , Rotach Mathias W. , Obleitner Friedrich , Giovannini Lorenzo , Montagnani Leonardo
Published: March 2022

Observations from six eddy-covariance stations in the Austrian Inn Valley reveal a strong spatial variability in near-surface turbulent fluxes. While the stations are located within an approximately 6.5 km long section of the valley and thus within an area similar or even smaller than a single grid cell in current global weather forecasting models, the sites strongly differ in terms of topography and land use. Observed magnitudes of sensible and latent heat fluxes are driven by the solar incoming radiation and thus affected by the local slope angle and orientation, with further influences from the land use on the partitioning of the available energy into sensible and latent heat fluxes. In addition, the locally induced thermal slope- and valley-wind circulation impact the diurnal cycles of the turbulent fluxes. To correctly represent turbulent exchange in mountainous terrain in numerical models, the models thus need to represent all these conditions and processes correctly. We are running WRF simulations with a 1-km grid spacing as part of an ongoing project to evaluate land-surface models and turbulence parameterizations over complex terrain. The simulations are used to determine how sensitive the modeled land-atmosphere exchange is to inaccuracies in the topography and land use, which are unavoidable at this spatial resolution, and whether the model can reproduce the observed spatial variability.
Physics-informed machine learning to model rapid complex geohazards
Authors: Yildiz Anil , Zhao Hu , Kowalski Julia
Published: March 2022

Predictive simulations of rapid complex geohazards remains a challenge as it requires multiple computationally demanding tasks – such as model selection, parameter inversion or uncertainty quantification. Complexity of the geohazard herein refers to the dynamics of the event, i.e. 1962 and 1970 Huascarán events in Peru, both of which started as rock-ice falls – latter with a much larger release volume – and resulted in debris – ice avalanches. Recent efforts demonstrated the promising high estimation capability of inexpensive-to-built Gaussian process emulators to replace expensive-to-run landslide run-out simulations for predictive modelling. Furthermore, parameter inversion based on active Bayesian learning has recently been shown to greatly benefit from the developed surrogate models. Such demonstrations were conducted on rather simplistic cases with flow models that require low number of parameters. Inclusion of entrainment, complex topography, and higher number of model parameters inevitably increases the dimension of input parameter space. This study investigates the estimation ability of Gaussian process emulators to estimate the run-out characteristics of 1962 and 1970 Huascarán events by considering the spatial variation of model parameters and entrainment. A GIS-based open source landslide run-out model, r.avaflow v2.3, was used to simulate both events. Effects of high dimensionality of input parameter space on the performance metrics of emulation has been addressed by increased number of simulations and parameter reduction techniques. Parameter inversion has been performed to calibrate the model by using a synthetic simulation as ground truth. Inverting synthetic field observations for a known ground truth simulation result now allows us to assess the information content of different candidate data.
Structural failure and shallow dike intrusion at Nyiragongo volcano (D.R Congo)
Authors: Smittarello Delphine , Barrière Julien , d'Oreye Nicolas , Smets Benoit , Oth Adrien , Michellier Caroline , Shreve Tara , Grandin Raphael , Cayol Valérie , Wauthier Christelle , Derauw Dominique , Geirsson Halldor , Theys Nicolas , Brenot Hugues , Froger Jean-Luc , Muhindo Adalbert , Kervyn François
Published: March 2022

After January 1977 and January 2002, the third historically known flank eruption of Nyiragongo volcano and the first ever to be recorded by dense measurements both on the ground and from space started on the 22nd of May 2021, although no alarming precursory unrest had been reported. Nyiragongo lava flows threatened about 1 million of inhabitants living in the cities of Goma (Democratic Republic of Congo) and Giseny (Rwanda).

In the following days, seismic and geodetic data as well as fracture mapping revealed the gradual southward propagation of a shallow dike from the Nyiragongo edifice underlying below Goma airport on May 23-24, then Goma and Gisenyi city centers on May 25-26 and finally below the northern part of Lake Kivu on May 27. Southward migration of the associated seismic swarm slowed down between May 27 and June 02. Micro seismicity became more diffuse, progressively activating transverse tectonic structures previously identified in the whole Lake Kivu basin.

Here we exploit ground based and remote sensing data as well as inversion and physics-based models to fully characterize the dike size, the dynamics of dike propagation and its arrest against a structural lineament known as the Nyabihu Fault. This work highlights the shallow origin of the dike, the segmented dike propagation controlled by the interaction with pre-existing fracture networks and the incremental crater collapse associated with drainage which led to the disappearance of the world’s largest long-living lava lake on top of Nyiragongo.
Simulating climate effects on archaic human habitats and species successions
Authors: Timmermann Axel , Yun Kyungsook , Raia Pasquale , Zollikofer Christoph , Ponce de Leon Marcia , Willeit Matteo , Ganopolski Andrey , Zeller Elke , Ruan Jiaoyang , Zeller Elke
Published: March 2022

It has previously been suggested that climate shifts during the last 2 million years played an important role in the evolution of our genus Homo. However, quantifying this linkage has remained challenging. Here we use an unprecedented transient Pleistocene Coupled General Circulation model simulation in combination with an extensive compilation of fossil and archaeological records, to study the spatio-temporal habitat suitability of five hominin species over the past 2 million years. We show that astronomically-forced changes in temperature, rainfall and terrestrial net primary production had a major impact on their observed distributions. During the early Pleistocene hominins primarily settled in environments with weak orbital-scale climate variability. This behaviour changed drastically after the mid-Pleistocene-transition when archaic humans became global wanderers who adapted to a wide range of spatial climatic gradients, which increased  the likelihood for habitat overlap and cladogenic transitions. Our robust numerical simulations of climate-induced habitat changes provide a novel framework to test hypotheses on our human origin.
Self-awareness for robust miner robot autonomy
Authors: Aguado Esther , Sanz Ricardo , Rossi Claudio
Published: March 2022

Robustness and resilience are crucial requirements for robots operating in unstructured and hazardous environments, such as the systems developed within the ROBOMINERS project. The miner robot shall handle, at least to some extent, the disturbances it may suffer; especially given the reduced possibility of human intervention in deep, small, and difficult-to-access deposits. In ROBOMINERS, we use self-awareness mechanisms to enhance robot miner autonomy. This capability enables the robot to be aware of the state of all its components (both hardware and software) and to what extent they are complying with their functions. Moreover, self-aware systems can reason about the run-time state and detect the causes of system failures. Depending on the specific characteristics of the affected robot, failure management mechanisms can be implemented at different levels. Robots can be designed to change their physical or software configuration, change the functions of some of their components, or adapt their behaviour to match mission needs. Our approach uses the knowledge of the systems engineer through machine-readable metamodels to provide the robot with information about the mission, the environment, and itself. These formal models allow the system to reason about its run-time situation. The ROBOMINERS resilience-augmenting solution is based on deep modeling of the functional architecture of the autonomous robot in combination with runtime reasoning. The reflective reasoning of the robot allows for both self-diagnosis and reconfiguration during mining operations. One of the main advantages of this knowledge-centric approach is the explicit definition, allocation, and linkage of system requirements, design decisions, system realization, and run-time information. This approach can transparently use robot structural and functional redundancy to ensure mission satisfaction, even in the presence of faults. Moreover, the use of several meta-models and ontologies allows the segmentation of information into different domains and levels of abstraction. These independent assets can then be re-targeted and adapted to a variety of systems, sub-systems, and contexts to improve asset reuse.
Quantitative analysis of seismic waves attenuation: numerical analysis and laboratory-scale experiments.
Authors: Deheuvels Marine , Faucher Florian , Brito Daniel
Published: March 2022

In this work, we recover physical properties of a material with a focus on the attenuation, using a laboratory-scale sample. We develop a method to accurately invert the attenuation models, illustrating with 3D simulations the seismic wave propagation in the frequency domain considering different rheological viscoelastic models.

First, we consider a simplified numerical case where we avoid wave reflections from boundaries. Our analysis allows to characterize the wave behavior and the attenuation properties of the medium. Here, we use a complex wavenumber analysis, to recover a complex-valued mechanical modulus that accounts for the viscoelastic behavior.

Secondly, we consider numerically an experimental configuration, with free-surface conditions on the sample boundaries, and measurements restricted to the faces of the sample. In this case, the free-surface boundaries lead to multiple reflections and wave conversions that must be taken into account to analyze both the body waves and surface waves displacements to recover the representative viscoelastic properties. 

Finally, we carry out laboratory-scale experiments on various rock samples designed to find out their attenuation properties. For this purpose, we run an experimental setup using piezoelectric transmitters acting as a seismic source, and a laser-doppler vibrometer for non-contact time-domain measurements. Then, we have to recover the appropriate attenuation laws and their corresponding parameters, depending on the nature of samples. This eventually serves to build initial models to perform iterative reconstruction with Full Waveform Inversion.
Spectral optical properties of aerosols in Athens, Greece during the August 2021 wildfires and their effects on surface solar radiation
Authors: Fountoulakis Ilias , Raptis Ioannis-Panagiotis , Kouklaki Dimitra , Kosmopoulos Panagiotis , Psiloglou Basil , Eleftheratos Kostas , Kazadzis Stelios
Published: March 2022

Multiple wildfire episodes have been observed in Greece during August 2021, after a historic heatwave, with temperatures exceeding 45°C. Two of the most destructive wildfires were in Attica and Euboea with smoke plumes covering the city of Athens and affecting significantly not only the air-quality and also the levels of surface solar radiation. During these events, spectral optical properties of aerosols were measured at NOA’s actinometric platform in Athens, Greece (Thissio site: 23.7°E, 37.6°N) by a CIMEL sun-photometer, and are analyzed in the context of this study. Measurements from a lidar ceilometer, satellite images, and back-trajectories are also used to identify the origin of aerosols during the smoke, but also combined dust and smoke events in low-aerosol days in the same month. Spectral measurements of the direct and diffuse solar irradiance from the Precision Solar Spectroradiometer (PSR) and measurements of the global and diffuse irradiance from precision pyranometers were also available in Athens, used to investigate the effects of different aerosol types on the levels of surface solar radiation measured. Furthermore, the efficiency of the nowcasting and forecasting tool nextSENSE, used to simulate and predict the levels of surface solar radiation, has been evaluated under such conditions.

Acknowledgements

This study was funded by the EuroGEO e-shape (grant agreement No 820852) and the H.F.R.I. National Research Project ASPIRE (project number 300).
Investigating Rift-Rift-Rift triple junctions through analogue and numerical modelling
Authors: Maestrelli Daniele , Corti Giacomo , Brune Sascha , Keir Derek , Sani Federico
Published: March 2022

Continental break-up at Rift-Rift-Rift triple junctions commonly represents the “prequel” of oceanic basin formation. Currently, the only directly observable example of a Rift-Rift-Rift setting is the Afar triple junction where the African, Arabian and Somalian plates interact to form three rift branches, two of which are experiencing oceanization (the Gulf of Aden and the Red Sea). The younger of the three (the Main Ethiopian Rift) is still undergoing continental extension. We performed analogue and numerical models simulating continental rifting in a Rift-Rift-Rift triple junction setting to investigate the resulting structural pattern and evolution. By adopting a parametrical approach, we modified the ratio between plate velocities, and we performed single-phase (all the three plates move) and two-phase models (with a first phase where only one plate moves and a second phase where all the three plates move). Additionally, the direction of extension was changed to induce orthogonal extension only in one of the three rift branches. Our single-phase models suggest that differential extension velocities in the rift branches determine the localization of the triple junction, which is located closer to the rift branch experiencing slower extension velocities. Furthermore, imposed velocities affect the distribution of deformation and the resulting pattern of faults. The effect of a faster plate is to favour the formation of structures trending orthogonal to dominant velocity vectors, while faults associated with the movement of the slower plates remain subordinate. In contrast, imposing similar velocities in all rift arms leads to the formation of a symmetric fault pattern at the triple junction, where the distribution of deformation is similar in the three rift branches. Two-phase models reveal high-angle faults interacting at the triple junction, confirming that differential extension velocities in the three rift branches strongly affect the fault pattern development and highlighting geometrical similarities with the Afar triple junction.
Solar Wind Structures and their Effects on the High-Energy Tail of the Precipitating Energetic Electron Spectrum
Authors: Salice Josephine , Tyssøy Hilde Nesse , Smith-Johnsen Christine , Babu Eldho Midhun
Published: March 2022

Medium energy electron (MEE) (>30 keV) precipitation into the Earth's atmosphere is acknowledged as a relevant part of solar forcing as collisions between electrons and atmospheric gasses initiate several chemical reactions which can reduce ozone concentration. Ozone is critically important in the middle atmosphere energy budget as changes in ozone concentration impact temperature and winds. There is an ongoing debate to which extent the existing geomagnetic parameterizations represent a realistic precipitating flux level, especially when considering the high energy tail of MEE (>300 keV). An improved quantification might be achieved by a better understanding of the driving processes of MEE acceleration and precipitation, alongside optimized data handling. In this study, the bounce loss cone fluxes are inferred from MEE precipitation measurements by the Medium Energy Proton and Electron Detector (MEPED) on board the Polar Orbiting Environmental Satellite (POES) and the Meteorological Operational Satellite Program of Europe (METOP) at tens of keV to a couple hundred keV. It investigates MEE precipitation in contexts of different solar wind structures: corotating interaction regions (CIRs) associated with high-speed solar wind streams (HSSs), and coronal mass ejections (CMEs), during an eleven-year period from 2004 – 2014. The objective of this study is to explore general features of the MEE precipitating spectrum in the context of its solar wind driver: the intensity of MEE alongside the intensity and delayed response of its high energy tail.
Saharan dust vertical distribution is controlled by convection and scavenging. Why do models miss this?
Authors: Pilon Romain , Senghor Habib , Diallo Binta , Escribano Jeronimo , Hourdin Frederic , Grandpeix Jean-Yves , Boucher Olivier , Gaye Amadou Thierno , Machu Eric
Published: March 2022

Saharan dust represents more than 50% of the total desert dust emitted around the globe and its radiative effect significantly affects the atmospheric circulation at a continental scale. Atmospheric models often fail to represent the dust vertical distribution and the Saharan Air Layer. They underestimate the effects of deep convection on the vertical transport and of the role of scavenging on the confinement of dust aerosols in this layer. Using multi-year simulations performed with a variable-resolution climate model and processed-based analysis, we show that scavenging in deep convection and further re-evaporation of dusty rainfall in the lower troposphere are critical processes for explaining the vertical distribution of desert dust. They play a key role in maintaining a well-defined dust layer with sharp transition at the top of the SAL and in establishing the seasonal cycle of dust distribution.
Contemporary stratification constrains future anthropogenic carbon and excess heat uptake in the northern limb of the Southern Ocean
Authors: Bourgeois Timothée , Goris Nadine , Schwinger Jörg , Tjiputra Jerry F.
Published: March 2022

The Southern Ocean is a major sink of anthropogenic carbon and excess heat. The Earth system model projections of these sinks provided by the CMIP5 and CMIP6 scenario experiments show a large model spread contributing to the large uncertainties in climate sensitivity and remaining carbon budgets for ambitious climate targets. A recent study identified an emergent coupling between anthropogenic carbon and excess heat uptake, highlighting that the passive-tracer behavior of these two quantities is dominant under high-emission scenarios. This coupling indicates that the use of a single observational constraint might be sufficient to reduce projection uncertainties in both anthropogenic carbon and excess heat uptake. In the northern limb of the Southern Ocean (30°S-55°S) where the subduction of intermediate and mode water is known to drive carbon and heat uptake, we find that the variations in model´s contemporary water-column stability over the first 2000 m is highly correlated to both its future anthropogenic carbon uptake and excess heat uptake efficiency. Using observational data, we reduce the uncertainty of future estimates of (1) the cumulative anthropogenic carbon uptake by up to 53% and (2) the excess heat uptake efficiency by 28%. Our results show that improving the representation of water-column stratification in Earth system models should be prioritized to improve future anthropogenic climate change projections.
Quasi-2-Day Wave in Low-Latitude Atmospheric Winds as Viewed From the Ground and Space During January–March, 2020
Authors: He Maosheng , Chau Jorge L. , Forbes Jeffrey M. , Zhang Xiaoli , Englert Christoph R. , Harding Brian J. , Immel Thomas J. , Lima Lourivaldo M. , Rao S. Vijaya Bhaskar , Ratnam M. Venkat , Li Guozhu , Harlander John M. , Marr Kenneth D. , Makela Jonathan J.
Published: March 2022

In the mesosphere and lower-thermosphere, quasi-2-day waves are spectacular planetary-scale oscillations. Almost all relevant observational studies are based on ground-based single-station or single-satellite methods and, therefore, cannot determine the zonal wavenumber unambiguously. We employ a series of multi-station methods on winds measured by four longitudinally separated low-latitude ground-based radars in the current work. These methods help us to determine two dominant zonal wavenumbers at 80–100 km altitude. These results are used to complement satellite measurements. The agreement between datasets is extraordinary, allowing us to extend the characteristics of the waves to higher altitudes using satellite measurements.

The current work was published in He et al. (2021, https://doi.org/10.1029/93jd00380), which was extended into a broad altitude range up to the topside F-region in Forbes et al. (2021, https://doi.org/10.1029/2021JA029961).
Fractionating German agricultural soils to assess if the mineral associated carbon fraction saturates 
Authors: Neha Neha , Poeplau Christopher
Published: March 2022

Soil organic carbon (SOC) saturation is generally defined as soil’s unique limit to stabilize C, which is dependent on soil physio-chemical characteristics. It is claimed that if once the mineral fraction is saturated, no additional carbon input leads to mineral-associated organic carbon (MAOC) accrual. However, the capacity of a specific soil to store MAOC may depend on many factors, and experimental evidence of actual saturation is scarce. Earlier defined saturation points appear to be statistically biased since especially agricultural soils with high SOC contents are rare so that the strong linear relationship between MAOC and total SOC becomes less clear at higher SOC contents.

To assess, whether the amount of MAOC saturates at a certain point, we used the opportunity of a comprehensive soil archive. From a total of 3104 topsoil samples collected during the German Agricultural Soil Inventory, we took a systematic random sample (n=190) with a wide range in SOC (0.54 - 11.7 %) and clay content (3-77%). We thereby ensured, that an equal number of samples were selected in each SOC content class, which were defined in steps of 1% SOC to ensure an unbiased evaluation of a potential saturation point.  Those soils are being fractionated into Particulate Organic Carbon (POC) and MAOC. Firstly, soils are subjected to ultrasonic dispersion followed by particle size separation via wet sieving (50 µm). SOC and total nitrogen will be determined in each sample. The first results of this study will be presented, which will shed more light on an important aspect of SOC dynamics.
Characteristics of ice-nucleating particles in Beijing during Spring: a comparison study for the suburban and a nearby mountain area
Authors: Hu Yaqiong , Tian Ping , Huang Mengyu , Bi Kai , Schneider Julia , Umo Nsikanabasi S. , Ullmerich Nikolas , Höhler Kristina , Jing Xiaoqin , Xue Huiwen , Ding Deping , Liu Yongchun , Leisner Thomas , Möhler Ottmar
Published: March 2022

Ice-nucleating particles (INPs) are of great importance for regional weather and climate by altering the microphysical properties of clouds. Large uncertainties still exist for the sources, abundance and variability of INPs over the polluted North China Plain (NCP) due to limited observations in this region and the complex physical and chemical properties of aerosols from multiple sources. In this study, the concentrations of INPs in the immersion freezing mode at temperatures ranging from -5 ℃ to -30 ℃ were simultaneously measured for about one month in the Spring season. The measurements were carried out at a mountain site and a suburb site in Beijing representing clean and anthropogenic condition, respectively. Different concentrations and characteristics of INP are found for the two sites, which reflect the influence of different the air masses and INP sources. Consistent with previous studies in this region, dust particles are found to be the most abundant INPs during the Spring season, and the contribution from anthropogenic pollution aerosols was of minor importance. Most interestingly, the INP concentration at the mountain site was about one magnitude higher than at the suburban site at temperatures higher than -10 ℃, which is caused by the primary biological aerosol from the forests in the moutain area. Our results characterize the important role of these bioaerosols, which are also expected to have a strong impact on the glaciation of orographic clouds.

In addition, to extend the data set, we investigated the characteristics of INPs in other seasons, to further study and quantify seasonal cycles of INP concentrations and sources.
Impact of inherited geometries on syn-orogenic foreland basin
Authors: Gérard Benjamin , Rouby Delphine , Huismans Ritske , Robin Cécile
Published: March 2022

Foreland basins record the evolution of orogens through sedimentary accumulation and recycling and, as such, represent unique archives of the evolution of orogenic systems. Foreland basins are, however, complex source-to-sink systems responding to the uplift of the mountain range, thrusting, eustasy, climate, and the type of lithologies eroded. The respective contributions of these parameters has been numerically evaluated, the influence of the inherited geometries of the foreland on the sediment routing systems has not yet been investigated.

We use a Landscape Evolution Model (FastScape) to explore the effect of varying foreland paleo-topography on its stratigraphic architecture. Models consist of a half mountain range steadily uplifting (0.5 mm/yr) over 25 Myrs. Eroded material is transported and deposited in a foreland domain and a distal open marine domain. We present 4 setups with varying paleo-topographies in the foreland domain: an initial flat foreland at sea level (M1), an elevated flat continental foreland (+300 m, M2), a pre-existing 1 km-deep and 100 km-wide depression at the foot of the growing orogen with either a flat forebulge at sea level (M3) or an elevated forebulge (+300m; M4).

Our result show that an elevated foreland domain produces, after 25 Myrs, a thinner foreland basin because the faster and efficient sediment export of sediment out of the foreland to the open marine domain reduces the sedimentary load and, in doing so, the flexure. In contrast, a pre-existing depression at the foot of the range, produces a thicker foreland basin because the additional load filling the initial space increases the flexural response. We show that a pre-existing bathymetry is required to preserve marine deposits in the foreland basin. In our experiments, the landscape after 25 Myrs cannot be used to infer the initial foreland geometry as the initial foreland influences is smoothed out after ~10-15 Myrs. The stratigraphic architectures of the foreland basin are nonetheless different. In addition, we show that emplacement of an alluvial fan at the foot of the range results in a transient drop in erosion rate in the range by locally increasing the base-level (autogenetic feedback).
Incipient karst generation in three-dimensional jointed layered rocks: influence of aperture configurations and flow boundary conditions
Authors: Jiang Chuanyin , Wang Xiaoguang , Jourde Herve , Aliouache Mohammed
Published: March 2022

Karst aquifers provide considerable groundwater resources and supplies in many countries of the world. Karst systems exhibit complex spatial distributions of conduits, caves and vugs, but speleogenesis modeling remains very limited at aquifer scale. Early stage of wormholes development generally controls the final pattern of karst due to the positive feedback loop. In this study, we analyze the incipient karst generation in 3D jointed carbonate rocks with multiple horizontal layers, on the basis of numerical simulations. First, the fracture networks are generated while considering pseudo-mechanical rules for the nucleation and propagation of joints. Then, we analyze the impact of aperture configurations and flow boundary conditions on the dissolution patterns in such a 3D joint layered rock based on a developed hydro-chemical model. Preliminary results show that, for uniform apertures and horizontal flow, similar dissolution patterns are obtained whatever the flow orientations; bedding planes control and favor the tree-shape conduit networks while the joints promote the vertical spread. Results also show that karstification processes are dominated by the joint network structure and are significantly confined in individual layers when the aperture of bedding plane is lower than that of the joints. Changing flow boundary conditions (i.e. recharge and discharge from localized points instead of domain borders) tends also to induce different dissolution patterns. Compared to dissolution in a 2D fracture networks, these 3D reactive transport simulations further reveal the interaction of joint networks among different layers. This study has an important implication on understanding the initiation of different types of incipient karst patterns observed in nature.