bluuebunny/crossref_metadata_2025 huggingface dataset:
Towards an improved proxy for geomagnetically induced currents (GICs)
Authors: Gutiérrez Pinheiro Fernando Jorge , Neres Marta , Pais M. Alexandra , Alves Ribeiro Joana , Santos Rute , Cardoso João
Published: March 2022

The irregular variation of geomagnetic activity caused by the solar wind interaction with the magnetosphere/ionosphere (space weather) occurs in wide temporal and amplitude ranges. Major geomagnetic storms can induce geoelectric fields in the Earth conducting layers (through the lithosphere and down to the mantle), which may, in turn, be responsible for generating geomagnetically induced currents (GICs). The vulnerability of grounded conducting infrastructures, particularly electrical power transmission systems, to GICs, makes it important to understand the relation between the varying geomagnetic field components and the generated GICs, as well as the role of the local conductivity, i.e., geology, on the inducing process. Looking for proxies that better translate this relation is an open matter of debate.

In this work, we present a comprehensive study of several possible candidates for GIC proxies. We use geomagnetic time series from the Portuguese mid-latitude Coimbra observatory (COI) to calculate geomagnetic indices considering different periods (whole-storm duration, 3-h, 1-h and 1-min), with different focuses on the field components or their derivatives, and discuss their advantages and limitations. We compare the computed indices with both GIC simulations of the Portuguese mainland high voltage power network (150, 220 and 400 kV) (Alves Ribeiro et al., 2021), and observations from a Hall effect sensor based system installed at a power transformer located in the vicinity of Coimbra. 
We then propose a better GIC proxy, an index obtained from geomagnetic field components filtered by convolution with a uniform conductivity Earth model filter (EGIC index), based on previous work by Marshall et al (2010,2011). We search for empirical parameters that may contain information on local conductivity effects and power network geometry.

This study is funded by national funds through FCT (Portuguese Foundation for Science and Technology, I.P.), under the project MAG-GIC (PTDC/CTA-GEO/31744/2017). FCT is also acknowledged for support through projects UIDB/50019/2020-IDL, PTDC/CTA-GEF/1666/2020 (MN) and PTDC/CTA-GEO/031885/2017 (MN). CITEUC is funded by FCT (UIDB/00611/2020 and UIDP/00611/2020). We acknowledge the collaboration with REN (Redes Energéticas Nacionais).

References:
Alves Ribeiro J., F.J. Pinheiro, M.A. Pais, 2021. First Estimations of Geomagnetically Induced Currents in the South of Portugal. Space Weather, 19(1)
Marshall R. A., C. L. Waters, M. D. Sciffer (2010). Spectral analysis of pipe‐to soil potentials with variations of the Earth’s magnetic field in the Australian region. Space Weather 8.5
Marshall, R. A., et al (2011). "A preliminary risk assessment of the Australian region power network to space weather." Space Weather 9.10
Qualitative-enhanced full-waveform inversion of ground penetrating radar data
Authors: Fedeli Alessandro , Schenone Valentina , Pastorino Matteo , Randazzo Andrea
Published: March 2022

Ground penetrating radar (GPR) prospection of underground scenarios is proven useful in numerous fields, from geophysics to structural engineering. At present, most of the typically deployed approaches make use of qualitative processing of GPR data [1]. Nevertheless, despite their increased complexity, full-waveform inversion (FWI) methods are emerging as a key tool to provide a complete characterization of the buried region under test [2].

This contribution aims at presenting an innovative qualitative-enhanced FWI strategy that combines the benefits from these different classes of GPR processing methods. In more detail, on the one hand a synthetic aperture-based technique retrieves a first qualitative map of the buried structures. On the other hand, the dielectric properties of buried targets are found by an FWI approach formulated in the unconventional context of nonconstant-exponents Lebesgue spaces [3]. The FWI procedure exploits the qualitative map for guiding the unknown update, as well as for constructing the nonconstant-exponent function. Both numerical and experimental results are discussed to assess the proposed inversion procedure.

[1] R. Persico, Introduction to Ground Penetrating Radar: Inverse Scattering and Data Processing. Hoboken, New Jersey: Wiley, 2014.

[2] M. Pastorino and A. Randazzo, Microwave Imaging Methods and Applications. Boston, MA: Artech House, 2018.

[3] V. Schenone, A. Fedeli, C. Estatico, M. Pastorino, and A. Randazzo, “Experimental Assessment of a Novel Hybrid Scheme for Quantitative GPR Imaging,” IEEE Geoscience and Remote Sensing Letters, vol. 19, pp. 1–5, 2022.
A full year reanalysis of European air quality in 2016 focusing on the evaluation of anthropogenic emissions by applying advanced spatio-temporal inversion
Authors: Lange Anne Caroline , Franke Philipp , Elbern Hendrik
Published: March 2022

Emission data as main input to air quality forecast models introduce large uncertainties. These data originate from emission inventories that provide estimates of spatially distributed emissions in general as an annual total amount. The temporal variations of the emission data follow prefixed time profiles in models. Yet, the impact of variable societal behaviour and meteorological implications are rarely considered. Furthermore, environmental agencies that raise the data input for emission inventories depend on rough emission estimates from bottom-up and top-down strategies.

To evaluate the annual emission totals of European and in particular German inventories, we perform a full year reanalysis of European air quality in 2016 applying chemistry four-dimensional variational (4D-var) data assimilation with the European Air pollution Dispersion – Inverse Model (EURAD-IM). Assimilating ground-based, airborne, as well as satellite observation data within 24 hours assimilation windows, we successively assess initial value optimisations and emission correction factors for anthropogenic emissions of nitrogen oxides (NOx), carbon monoxide (CO), particulate matter (PM), sulphur oxides (SOx), ammonia (NH3), and non-methane volatile organic compounds (NMVOCs), achieving consistency with observations. The analysis is performed on different model grids of 15 km horizontal resolution for Europe, 5 km for Central Europe, and 1 km for three selected regions in Germany.

Analysing the inferred temporal evolution of emission correction factors reveals that the total NOx emissions are underestimated in Germany, while NH3 emissions are found too high leading to an overestimation of modelled NH3 concentrations using standard emission data. Other emission species show clear seasonal dependence in the correction factors. Comparing the emission correction factors of the different European countries, we find a significant discrepancy of correction strengths between north-western and south and eastern European countries. Analysis results for different model nests vary not only due to finer structures but also in the strength or sometimes even the direction of corrections. Spatially, the distribution of correction factors is driven by areas characterized by high emissions while care must be taken that the deployment of assimilated observation stations still matters. In this context, we also discuss the limits of our analysis technique regarding the observation network configuration and the statistical method of the assimilation technique.
Development of innovative remote sensing techniques and tools for mapping marine bioindicators and their potential responses to specific anthropogenic pollutants
Authors: Varini Fabrizio , Madonia Alice , Piermattei Viviana , Piazzolla Daniele , Marcelli Marco
Published: March 2022

The coastal marine environment is a key area for humans with more than 40% of the European population concentrated on coastal regions. Coastal areas are densely populated and often host industrial activities which have the potential to generate pollution.

Anthropogenic impacts overlap with climate change that can amplify the effects of pollution on marine ecosystems.

A modern strategy of investigation of the coastal marine environment requires the development of remote sensing methods useful to acquire information on numerous characteristics of marine ecosystems. Particular attention is given to the mapping of benthic ecosystems which are capable to record the effects of pollution events and could respond with changes in their composition and community structure, but also in the spectral signature as already studied for some algal species. Importance is given to the selection of new bioindicators to assess the ecological quality of benthic biocenosis of coastal marine ecosystems through remote sensing observations, integrating platforms data at different spatial scales. Moreover, once the target species have been identified, it is possible to interpret variations in the spectral response that allow to identify and quantify the impacts of pollutants that are released into the sea directly or indirectly by human activities.

This work is part of the STOPP project (Strumenti e Tecniche di Osservazione della Terra in Prossimità e Persistenza), funded by ASI (Agenzia Spaziale Italiana), and aims to (I) map seagrasses and macroalgae species applying remote sensing methodology (e.g., Leaf Area index – LAI); (II) select target species that can respond to certain pollutants through variations in the spectral signature; (III) develop an innovative methodology for the monitoring and mapping of marine bioindicators by detecting "target wavelengths" caused by the impact of chemical pollutants on seagrasses and macroalgae species.
The role of environmental extremes on urbanized areas of Western Hungary
Authors: Horváth Adrienn , Balázs Pál , Bolodár-Varga Bernadett , Csáki Péter , Gribovszki Zoltán , Kalicz Péter , Katona Máté , Szita Renáta , Végh Péter , Winkler Dániel , Bidló András
Published: March 2022

The impacts of climate change don’t appear only on natural areas but urbanized areas are also well affected. The unpredictable and extreme weather events

such as the alternation of drought periods and heavy, stormy precipitation events was typical in the last decades. Three settlements were investigated to detect how the extreme weather events influenced the water, sediment, and soil conditions on anthropogenic affected areas. The studied areas are mostly surrounded by mountains and forestlands and crossed by a river or creek; therefore, close-to-nature ideas, climate strategies, and sustainable urban management are needed to prepare against changing conditions. A heavy storm may increase the leaching of contaminants into soil and watercourses. To support the adaptation, city-wide investigations began in the last decade to make further suggestions for future direction based on measurements and experience. Altogether 672 soil samples and 30 sediment samples were analyzed to give a basis for climate strategy and settlement development concept in the future.

Project no. 141623 has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary from the National Research, Development and Innovation Fund, financed under the MEC_R_21 funding scheme.
Evaluation of sampling and sample preparation methodologies for multi-elemental analysis in foliage samples
Authors: Ali Saeed Waqar , Kocman David , Hudobivnik Marta Jagodic , Horvat Milena
Published: March 2022

Several approaches exist in literature for sample collection, preparation, and quantification of mercury concentration in foliage samples. Comparability of results from studies with varying methodological approaches are therefore critical for accurate estimation of vegetation control on Hg intercompartmental exchanges. To this end, field visits were carried out for the collection of foliar samples of Carpinus betulus in two forest sites in Slovenia having contrasting Hg source (Ljubljana as urban site and Idrija as Hg contaminated site). Foliage samples collected from different locations on the tree crown were then prepared to test the effect of washing on overall Hg foliar content. Each sample was then allowed to dry using selected procedures during their preparation for the determination of Hg content using ICP-QQQ-MS. Results show that the effect of sample treatment procedures on mercury concentration in foliar samples exhibit contrasting pattern with varying Hg source. Whereas the effect of washing was not evident on foliar samples collected from Ljubljana at mean Hg concentration of 9.85 ± 2.21 ng g-1, washing of foliar samples significantly decreased Hg concentration in foliar samples from Idrija (washed: 254.26 ± 120.30 ng g-1, unwashed: 392.94 ± 210.47 ng g-1, p=0.028). Variation in foliar Hg concentration within tree crown was evident both in Ljubljana (upper: 8.50 ± 1.16 ng g-1, outer: 8.85 ± 1.93 ng g-1, inner: 12.28 ± 1.04 ng g-1, p=0.005) as well as in samples from  Idrija (upper: 239.32 ± 201.76 ng g-1, outer: 390.62 ± 208.40 ng g-1, inner: 336.30 ± 85.70 ng g-1, p=0.04) with mean concentration of 322.34 ± 184.18 ng g-1, several folds higher than those reported in foliar samples from Ljubljana. Overall, different drying procedures did not cause significant change in foliar Hg concentration from Ljubljana however, foliar samples from Idrija that were dried in the oven at 60°C had lower Hg concentration possibly indicating Hg loss during the drying procedure. Our results demonstrate that the choice of sampling and sample preparation methodologies for determination of foliar Hg concentration are strongly influenced by the presence of Hg source in the studied area which is critical consideration for future studies.
Combined modeling and high-resolution monitoring approach for the assessment of nitrate-related redox processes at an agricultural site
Authors: Richard-Cerda Juan Carlos , Muñoz-Vega Edinsson , Knöller Kay , Schüth Christoph , Schulz Stephan
Published: March 2022

Biogeochemical redox processes control the chemical behavior of many major and trace elements. Nitrogen is particularly sensitive to changes in soil redox conditions and its presence also affects the cycles of other redox-sensitive species, which causes its excessive application through agricultural fertilizers to be a multi-faceted problem.

To assess these processes, we constructed a high-resolution monitoring station at an agricultural site featuring sensors and sampling facilities for analyzing hydraulics and hydrogeochemistry in the vadose zone and shallow groundwater. Monitoring has been performed for over two years during which different types of crops such as dill, spinach, wheat, and sunflower have been grown on the site. Observed variations of the oxidation-reduction potential over time and depth confirm the transient behavior of the redox reactive zone, whose variation is consistent with the fluctuation of the groundwater level. Also, a strong decrease in NO3- concentrations could be observed. This corresponds to changes over depthin both the sulfateconcentration and δ34S-SO42- signatures, whichconfirms the presence of autotrophic denitrification using sulfur as an electron donor. Moreover, a hydraulic model coupled with a heat transport model was set up for the estimation over depth of water fluxes, water content, and temperatures. In combination with the monitored concentrations, this allows us to estimate solute fluxes.

Preliminary results indicate an average nitrate input to groundwater of 200 kg·ha-1·a-1, which is almost completely reduced in the shallow groundwater. However, at the same time, a production of only 25 kg·ha-1·a-1 of sulfate is estimated, which indicates that not only sulfur serves as an electron donor, and thus heterotrophic denitrification must also be taking place. This can be confirmed based on increased bicarbonate concentrations in the reactive zone. Furthermore, other nitrate-triggered redox processes were detected, including selenium accumulation at the redox interface, presumably resulting from seleno-pyrite-driven denitrification and geogenic uranium roll-front mobilization.
Modeling of Reactive Transport in Porous Rock: Influence of Peclet Number
Authors: Shavelzon Evgeny , Edery Yaniv
Published: March 2022

Dissolution and precipitation processes in reactive transport in porous rocks play an important role in many contexts, such as geological CO2 storage, reactive contaminant transport, and acid injection in petroleum reservoirs. They are responsible for wormholing and alteration of the rock and transport characteristics due to feedback between the geochemical and the transport processes. A critical aspect of studying reactive transport is the influence of Peclet number on a coupled reactive process, which aims to understand the contributions of advection and diffusion as the two main transport mechanisms.

Our study investigates the influence of Peclet number on dissolution and precipitation processes in a porous calcite matrix due to reaction with the incoming low-pH flow using a particle tracking (Lagrangian) approach. The coupled reactive process is simulated in a series of computational analyses that capture the subtleties of the multiple scale heterogeneity phenomena, such as anomalous (non-Fickian) transport.

Our results show that reaction is manifested most significantly for small Peclet numbers, thus signifying the importance of diffusion in mixing processes that facilitate the reaction and increase the heterogeneity of the porous media. The evolution of the field heterogeneity due to reaction follows a similar trait, which is indirectly supported by fractal dimension estimation. Related to the field heterogeneity is the Shannon entropy, which is considered as a measure of the self-organization of the flow.
A 39-year Convective Systems database using the TOOCAN cloud tracking algorithm and METEOSAT thermal infrared archive 
Authors: Fiolleau Thomas , Roca Rémy , Schulz Joerg , Viju John , Grant Michael
Published: March 2022

Mesoscale convective systems (MCs) are central to the water and energy cycle of the tropical region. Geostationary satellite observations can provide a useful resource to constraint theoretical and modelling perspectives of the convective systems. Thus, the MCS life cycle information can only be readily obtained using high frequency imagery available from the geostationary orbit. The METEOSAT series of satellites operated by EUMETSAT observe continuously the African and Atlantic region since more than 40 years and offer us the opportunity to improve our understanding of the MCS and to analyze their climatological trends over the region.

We will introduce a MCS database over the African and Atlantic regions built from the long-term thermal infrared METEOSAT first and second-generation archive and from a cloud tracking algorithm called TOOCAN spanning the 1981-2020 period.

The METEOSAT first and second-generation imagers exhibit some spectral window channels disparities, different temporal resolutions, and slight variability in the spatial resolution of the sensors. Moreover, the imagers of the early METEOSAT satellites were designed for qualitative analyses of weather patterns, and the quality of their data do not comply with climate requirements. Finally, the calibration procedure of each instrument is also performed at the individual level with instruments specifics mode of operation. The cloud tracking can be impacted by these various sources of inhomogeneity, and some technical specifications are then required to ensure the validity of the cloud-tracking and to build a 39-year homogenous MCS dataset.

First, by using the multi-sensor infrared channel calibration (MSICC) algorithm relied on the IASI, AIRS and HIRS/2 as reference observations, an intercalibration and spectral band adjustment of the IR long-term database has been performed to reduce the METEOSAT sensors differences. The spatial resolution has been homogenized by remapping each METEOSAT native projection to a 0.04° longitude-latitude equal-angle grid. A final effort has been performed to correct the limb darkening effect, and a careful quality control has been applied on each infrared image. The TOOCAN cloud tracking algorithm has then been applied to this homogenous long-term METEOSAT infrared dataset at a 30-min temporal frequency to build a 39-year tropical convective systems database giving an access to the morphological parameters of around 14×106 MCS along their life cycles.

Finally, we will present our preliminary analyses showing significant trends in MCS occurrence for different geographical regions.
A Probabilistic Assessment of the Causes of Active Deformation in the East Central Mediterranean Using Spherical Finite Element Models
Authors: Govers Rob , Herman Matthew , van de Wiel Lukas , Nijholt Nicolai
Published: March 2022

Plate boundary deformation zones represent a challenge in terms of understanding their underlying geodynamic drivers. Active deformation is well constrained by GNSS observations in the SW Balkans, Greece and W Turkey, and is characterized by variable extension and strike slip in an overall context of slow convergence of the Nubia plate relative to stable Eurasia. Diverse, and all potentially viable, forces have been proposed as the cause of the observed surface deformation, e.g., asthenospheric flow, horizontal gravitational stresses (HGSs) from lateral variations in gravitational potential energy, and rollback of the Hellenic slab. We use Bayesian inference to constrain the relative contribution of the proposed driving and resistive regional forces.

 

Our models are spherical 2D finite element models representing vertical lithospheric averages. In addition to regional plate boundaries, the models include well-constrained fault zones like north and south branches of the North Anatolian Fault, Gulf of Corinth and faults bounding the Menderes Massif. Boundary conditions represent geodynamic processes: (1) far-field relative plate motions; (2) resistive fault tractions; (3) HGSs mainly from lateral variations in topography and Moho topology; (4) slab pull and trench suction at subduction zones; and (5) coupling between the lithosphere and the underlying asthenosphere. The magnitude of each of these is a parameter in a Bayesian analysis of ~100,000 models and horizontal GNSS velocities. The search yields a probability distribution over all parameters, allowing us to determine mean/median parameter values, robustly estimate parameter uncertainties, and identify tradeoffs (i.e., parameter covariances).

 

The average viscosity of the overriding plate is well resolved 3-4 ·1022 Pa.s, which is higher than published models without faults. Significant trench suction forces from the Hellenic slab act on the overriding Aegean Sea, including along the Pliny-Strabo STEP Fault. Slab pull and convective tractions have little imprint on the observed deformation of the overriding plate. HGSs are necessary to explain local features in the velocity field, particularly in the Aegean Sea, but are less important for fitting the regional pattern of velocities. Resistive tractions on most plate boundaries and faults are low. The best-fitting models compare well with paleomagnetic rotations and geological fault slip rates from previous studies.
High latitude ionospheric electric field models comparison
Authors: Orr Lauren , Grocott Adrian , Walach Maria , Lam Mai Mai , Freeman Mervyn , Chisham Gareth , Shore Robert
Published: March 2022

Modern high latitude ionospheric electric field models have been developed to incorporate advances in data availability, however the use of older spacecraft-based models is still widespread.  AENeAS (Advanced Ensemble electron density [Ne] Assimilation System) is a physics-based, thermosphere-ionosphere, coupled, assimilative model, which makes possible thermospheric forecasts. Currently AENeAS uses the Heelis and Weimer electric field spacecraft climatology models but it is possible a more recent electric field model could improve its functionality.  Two such models are calculated using line-of-sight velocity measurements from the Super Dual Auroral Radar Network (SuperDARN): the Thomas and Shepherd model (TS18), and the Time-Variable Ionospheric Electric Field model (TiVIE) . Here we compare the electric field models during the September 2017 storm, covering a range of solar wind and interplanetary magnetic field (IMF) conditions. We explore the relationships between the IMF conditions and model output parameters such as transpolar voltage, the polar cap size and the lower latitude boundary. We find the spacecraft-based model electric potential and field parameters to have a significantly higher magnitude than the SuperDARN-based models. We will discuss the similarities and differences in topology and magnitude for each model.
Regional hydrological response to climate change across Sweden - impact modelling and communication
Authors: Capell Rene , Musuuza Jude , Berg Peter , Bosshard Thomas , Lindström Göran
Published: March 2022

Changes in climatic forcing will change regional hydrological responses, both long-term seasonal dynamics and extreme events. Impact assessments are urgently needed by decision makers for climate adaptation planning, despite the uncertainties in the impact model chain. Therefore, uncertainties in impact assessments need to be evaluated and communicated along with the actual results in a transparent and user-friendly way.

Here, we show results from a hydrological climate impact study for Sweden, which is communicated to regional planners through a web-based assessment tool (smhi.se/en/climate/future-climate/advanced-climate-change-scenario-service/hyd). Climate change impacts are expected to alter seasonal hydrological dynamics as well as hydrological extremes in the region. We use a modelling framework based on a calibrated national hydrological model, S-HYPE, which divides the domain into  ~ 35000 computational sub-basins, for which hydrological states and fluxes are computed using a conceptual process model including lake and river management routines. S-HYPE is forced with an ensemble of Euro-CORDEX regional climate forcing for a 1971 to 2100 assessment period and representative concentration pathways 2.6, 4.5, and 8.5. All forcing is bias-corrected to a gridded reference forcing data set using quantile mapping. Results are communicated in a spatially aggregated form for ~ 250 river basins using climate impact indicators (CII), which highlight expected change patterns for specific parts of the hydrolgical cycle, e.g. change in maximum annual snow water equivalent or summer discharges. Uncertainties are communicated through ensemble spread and robustness measures, allowing users to directly assess at least parts of the uncertainty in the model results.

We also use the modelled results for a comparative analysis of change impacts across river basins in Sweden, taking advantage of the north-south climate gradient across the domain. This allows for a direct comparison of modelled today and future behaviour of similar river basins across that gradient to evaluate the uncertainty in future impacts which orginate in the model representation of interactions and feedbacks between climate and hydrological system within the S-HYPE model framework.
Analysis of the western Mediterranean cyclone characteristics for the past decades
Authors: Dolgos Emília , Pongrácz Rita , Bartholy Judit
Published: March 2022

Large scale circulation patterns are highly affected by midlatitude cyclones, their evolution, intensity, associated weather events (e.g., precipitation, consequent flood, etc.). The current study focuses on the western Mediterranean region where cyclones definitely play an important role in shaping the weather and climate of the area. Moreover, this region is considered as one of the most vulnerable areas to climate change, which implies the need for special attention. As the literature highlights, the geographical complexity of the Mediterranean region provides ideal conditions for cyclogenesis. Detailed analyses and a better understanding of the Mediterranean cyclones are crucial to develop proper adaptation strategies addressing future regional climate changes. For this purpose, we aim to analyze western Mediterranean cyclones on the basis of reanalysis data as reference, and then, compare the results of the historical runs of global climate models to the reference results. The analysis uses mean sea level pressure data from 1901 to 2020 with 6-hour temporal resolution, and daily precipitation in the western Mediterranean region and its vicinity. The results can serve as important input for impact modelers to further analysis and for decision makers to take into account when building long-term strategies.
Modeling the surface-atmosphere coupling in the Moroccan semi-arid plains in the context of climate change
Authors: Arjdal Khadija , Driouech Fatima , Vignon Étienne , Chéruy Frédérique , Sima Adriana , Drobinski Philippe , Chehbouni Abdelghani , Er-Raki Salah
Published: March 2022

Morocco as many semi-arid Mediterranean and north African countries is facing strong pressure on water resources exacerbated by climate change. Assessing the representation and variability of the Moroccan climate by using the climate models is of major importance to strengthen the reliability of future scenarios and anticipate the water cycle evolutions.

The aim of this study is to evaluate and improve the representation of the surface-atmosphere coupling, and the boundary-layer dynamics over the Haouz plain by the IPSL-CM Earth System Model. The Haouz plain is one of the most important agricultural and touristic regions of Morocco. It is located in the Tensift watershed and limited with the Atlas mountains, and it has been equipped with a network of meteorological stations. We set a simulation configuration up with a model grid refined over the Haouz plain and with a nudging towards atmospheric reanalysis outside the plain, making it possible to concomitantly compare the model outputs with in-situ data. 

A first evaluation of the control simulation reveals an overall good agreement between the observed daily mean temperature and the simulated one despite some cold biases. Simulated near-surface relative humidity is generally low-biased (up to 20%) while precipitation is overestimated (up to 50% of observed daily precipitation). Those biases are further deciphered through a careful evaluation of the different terms of the surface energy and water budgets. Complementary analyses conditioned to the direction of the large scale flow also investigate how model’s performances over the plain depend on the representation of the orographic flow over the Atlas. This evaluation work is a preliminary and an important step to identify which and how LMDZ parameterizations have to be improved for semi-arid African regions. 
The fifth generation regional climate modeling system RegCM5: Description and model validation over all CORDEX domains at hydrostatic and conveciton-permitting resolutions
Authors: Coppola Erika ,   RegCM team
Published: March 2022

A new limited area model able to perform at a broad resolution range spanning from hydrostatic to convection permitting resolution  was needed to serve the big RegCM community when exploring the new frontiers of the regional climate modelling science . For this purpose the new RegCM5 non-hydrostatic core has been implemented. The new core  solves the dynamical equations by using a Weighted Average Flux (WAF) advection scheme with implicit vertical sound waves propagation, discretized on a horizontal Arakawa C-grid with terrain following hybrid height coordinate and Euler time integration, using split time-steps for both advection and vertical sound waves. No explicit diffusion is included except for a divergence damping. The model physical packages are adapted from the RegCM4. RegCM5 has been fully tested on all the CORDEX-CORE domain and in several convection permitting domains already used with the previous model version. The model integration time is on average four time faster compared to the previous version given that a larger time step is allowed for the integration. The RegCM5 results have been compared with the previous CORDEX-CORE simulations to assess the model ability in reproducing the regional climate in all the world regions and improvements in model statistics have been founds in several domains.  
The role of surface coupling, turbulent mixing, and radiation in modeling a stable boundary layer over Tibetan Plateau
Authors: Ding zhangwei , Steeneveld Gert-Jan , Ma Yaoming , Chen Xuelong
Published: March 2022

To enhance the understanding of the impact of small-scale processes in the polar climate, this study focuses on the relative role of snow-surface coupling, radiation and turbulent mixing in stable boundary layer over Tibetan Plateau. This is the first attempt to reveal physical processes under stable stratification with WRF-3D model. All cases are characterized by three different stable boundary layer archetypes, namely, a radiative night, an intermittently turbulent night, and a fully turbulent night (all at clear-sky conditions). First a set of WRF configurations that vary in parametrization schemes for the planetary boundary layer, and land surface are evaluated. we find a wide variety in the state of the atmosphere and the surface variables for the selected parameterization schemes after intercomparisons. To understand this variety, we implement the sensitivity runs to examine which physical process is most crucial, using a unique analysis method so-called ‘process diagrams’. The variation between the sensitivity runs display a relative orientation of model sensitivities to variations in each of the governing processes and these can explain the variety of model results obtained in the intercomparison of different parameterization schemes.
The magnetopause discontinuity: a MMS study.
Authors: Ballerini Giulio , Belmont Gerard , Rezeau Laurence , Califano Francesco
Published: March 2022

The magnetopause boundary seems to escape the general classification of discontinuities since it mixes characteristics of shocks (magnetic field magnitude increase) and those typical for the rotational discontinuities (magnetic rotation), whereas it is very often described as a tangential discontinuity. As, the main issue is the amount of matter/momentum/energy from the solar wind and entering into the magnetosphere, the solution cannot be simply achieved by assuming the discontinuity as strictly tangential, everywhere and at all times. Here we propose to study the magnetopause boundary as a "quasi-tangential" discontinuity, with the normal magnetic component Bn small but not null since even small departures from the standard hypothesis of a zero Bn can lead to noticeable changes in the global properties. In that aim, we look into the MMS database for a large number of magnetopause crossings. For each case we will determine what are the most important features (non-planarity, non-stationarity, Hall effect, pressure anisotropy and agyrotropy) that allow the discontinuity to escape the general classification, i.e. to noticeably change the form of the conservation laws on which the theory of discontinuities is based for non-strictly tangential discontinuities. We put a special emphasis on the refined methods that can be used for determining the spatial gradients from four spacecraft data and on the accuracy that can be attained by these methods.
Brother TGF
Authors: Navarro-González Javier , Connell Paul , Eyles Chris , Reglero Víctor , López jesús A. , Montanyà Joan , Marisaldi Martino , Mezentzev Andrew , Kochkin Pavlo , Lindanger Anders , Sarria David , Østgaard Nikolai , Chanrion Olivier , Christiansen Freddy , Neubert Torsten
Published: March 2022

ASIM TGF catalog presents more than one thousand TGF from June 2018 till the end of 2021. Using this dataset, the detection rate of TGF by ASIM was about one TGF per day. The TGF detection is a stochastic process (each TGF is not related with the next) assuming this, the time-difference distribution between one detection and the next should fit an exponential distribution. This time between TGF events distribution fits the exponential with a significant deviation. We see an excess in the number of TGF separated by less than 5 min. From the expected value of less than 1% of the events, we have an 8% of the events in this range. We call that TGF population with a time separation of fewer than 5 minutes “Brother TGF”. Large storm areas could explain this deviation, because of the storm size or also the propagation effects of the TGF inside the storm as an effective mechanism to increase the TGF production in this region. This work we present is a detailed study of the most relevant “Brothers” in the ASIM TGF imaging list. With this, we can locate where these Brothers TGF are located, and add some clues about this Brother TGF production mechanism.
Ocean temperature forcings in glacial-interglacial Antarctic Ice Sheet simulations 
Authors: Chandler David , Langebroek Petra , Reese Ronja , Albrecht Torsten , Winkelmann Ricarda
Published: March 2022

Ice shelf basal melt accounts for about half the present-day ice loss from the Antarctic Ice Sheet, and is important for both ice sheet mass balance and as a source of fresh water into the Southern Ocean. In Antarctic Ice Sheet simulations over Quaternary glacial cycle time scales, neither basal melt rate nor its principal oceanographic controls (temperature and salinity of waters adjacent to ice shelves) can be reconstructed directly from proxy records. Given the strong ice-ocean-atmosphere interactions, the ideal solution is a coupled ice-ocean-atmosphere model, but computational demands currently limit this approach to short time scales. Stand-alone ice sheet simulations can cover much longer time scales at reasonable resolution, but require an alternative estimate of ocean temperatures. Here we compare the strengths and weaknesses of three options: (i) proxy reconstructions of North Atlantic and circumpolar deep water temperatures, from marine sediment cores north of 43°S; (ii) an ice sheet air temperature reconstruction, damped and lagged by a linear response function; and (iii) a glacial index method which interpolates between CMIP6 lig127k (interglacial) and lgm (glacial) end-member ocean states. We find considerable differences in the rates and magnitudes of the Antarctic Ice Sheet's contribution to past sea-level changes when applying the three methods in simulations over the last two glacial cycles, particularly during the last interglacial and Holocene. Therefore, the ocean temperature forcing remains as an important but poorly-constrained modelling choice, whether investigating past warm climates or using long simulations as a spin-up for future projections. 
Facies distribution along the salt diapirs of the Cotiella mini-basins (Southern Pyrenees, Spain)
Authors: Kalifi Amir , Ribes Charlotte , Ringenbach Jean-Claude , Dujoncquoy Emmanuel , Muñoz Josep Anton , Callot Jean-Paul
Published: March 2022

Most of the studies focusing on salt-tectonics are limited concerning high-resolution facies variations (seismic resolution/outcrop conditions) and reservoir distribution in salt diapir-flanking strata (few wells). As a consequence, many questions remain unsolved, such as the relation between the type of halokinetic sequences and the facies distribution, the interplay between sedimentary environments and the local halokinetic context. The aim of this study is to better understand spatial and temporal facies distribution and resulting sedimentary stacking pattern along the Cotiella mini-basins salt structures (Spanish Pyrenees).

Our approach is dedicated to detailed field mapping, sedimentological description of the stratigraphic succession as well as the investigation of the facies partitioning and depositional systems along within these exceptionally well exposed group of MBs. There, syn-halokinetic strata deposited during the Middle Coniacian to Early Santonian post-rift succession. Preliminary results show that:

The Cotiella mini-basin is characterized by a megaflap involving a 130° salt-controlled growth-strata. The Armeña mini-basin corresponds to a salt-expulsion roll-over characterized by a 80° salt-controlled growth-strata. Armeña formed mostly before Cotiella.

Depositional environments correspond to type-ramp mixed siliciclastic-carbonate platform. The sedimentological succession is composed by a parasequence stack characterized by proximal quartz-rich facies located mainly along the salt-weld and evolving laterally to more distal marine environments. Quartz are partly derived from the erosion of the salt-diapir, which correspond to the Keuper evaporitic facies containing authigenic quartz.

The stratigraphic successions of the Armena and Cotiella mini-basins is subdivided into 4 depositional sequences (S1a, S1b, S2, S3) but present specific thicknesses and facies partitioning, that suggest a strong control from the salt. These 4 sequences reveal the evolution from early to late stages of the rising salt-diapir.

Ultimately, and by integrating other mini-basins (i.e. mini-basins from the Sivas basin un Turkey), this study will help to better predict reservoir-facies and pinch-out locations along salt diapir-flanking strata.
The hydrological cycle in the past 540 million years
Authors: Hu Yongyun , Li Xiang , Li Zhibo
Published: March 2022

Earth has undergone dramatic temperature fluctuations and the tectonic process of continental breaking up and reassembling in the past 540 million years. How these caused changes in the global hydrological cycle is an interesting question. To study the evolution of the global hydrological cycle since the Cambrian, we carried out 55 equilibrium simulations to simulate climate evolution in the past 540 million years, using CESM1.2.2. It is found that the global mean precipitation is closely correlated with the global mean surface temperature (GMST), especially oceanic precipitation has high correlation with GMST, with a coefficient of 0.92. Land precipitation also has statistically significant correlation with GMST. However, the correlation coefficient is much lower. Further analysis shows that land precipitation is also determined by continental fragmentation, mean latitudes, and total area, and that the semi-arid area is most sensitive to GMST changes.
Hydrological partitioning of soil water in a hillslope segment using dual continuum model
Authors: Dusek Jaromir , Vogel Tomas
Published: March 2022

The existence of a hydraulically interconnected macropore network in the soil profile and the activation of preferential flow through this network during major rainfall events represent a significant difficulty in quantifying the temporal origin of soil water fluxes. The hydrograph separation technique based on the transport of stable water isotopes (or other conservative tracers) in soils in conjunction with a mass balance approach is usually used to partition the runoff into pre-event and event water contributions. For hillslopes located in a temperate climate, the pre-event water is recognized to form a dominant fraction of a stormflow hydrograph. In this study, one- and two-dimensional dual continuum models were used to study the preferential flow of water and the transport of oxygen-18 isotope in a hillslope segment located in a temperate spruce forest. The dual continuum model divides the heterogeneous bulk soil into the soil matrix and the preferential flow domain, with a possible exchange of water and isotope content between the domains. The isotopic composition of the hillslope flow shows distinct signatures of the preferential flow paths and the soil matrix due to the nonequilibrium conditions between the domains. As a result, imperfect mixing of the isotope tracer within the hillslope soil is predicted, leading to isotopically different water pools in the soil matrix and preferential pathways. Despite the dominant role of preferential flow in the generation of hillslope stormflow, the pre-event water formed 52–84% of the total subsurface stormflow, as reflected in the measured isotopic composition of shallow subsurface runoff.
Styles of seamount subduction and overriding plate deformation
Authors: Fonteijn Maaike , van Rijsingen Elenora , van Dinther Ylona
Published: March 2022

The subduction of seamounts and its accompanying crustal deformation of the overriding plate is thought to have a large effect on the occurrence of megathrust earthquakes. Subducted seamounts can generally only be observed using seismic-reflection studies, which have shown that seamounts can subduct intact down to 30-40 km depth. On the other hand, there is evidence for accreted seamounts in e.g. the Costa Rica and Makran subduction zones. Because such observations only provide snapshots in space and time, little is still known about the exact evolution of seamount subduction and its effect on overriding-plate deformation and subduction zone seismicity through time. We investigate the different styles of seamount subduction and how these influence seismicity and overriding plate deformation. We use seismo-thermo-mechanical (STM) models with a visco-elasto-plastic rheology simulating seamount subduction over millions of years in a 2D realistic subduction setting. The momentum, mass and energy equations are solved and a strongly slip rate dependent friction allows for the spontaneous development of faults. The use of a realistic rheology allows us to evaluate faulting patterns and the state of stress in the overriding plate caused by seamount subduction. We find three scenarios for seamount subduction by varying the rock properties cohesion (C) and pore fluid pressure ratio (λ): (1) cutting off of the seamount at the trench leading to frontal accretion; (2) intact subduction through the trench, followed by flattening and stretching of the seamount; and (3) intact subduction of the seamount until seismogenic depths. Scenario’s 1 and 2 are most common, while scenario 3 only occurs under a limited range of material parameters. Particularly, a cohesion of the seamount and upper oceanic crust larger than 20 MPa is required for intact seamount subduction. Decreasing λ on locations with ample amounts of fluids increases the strength of the sediments, upper oceanic crust and seamount, but does not lead to intact seamount subduction. Subduction scenario’s 2 and 3 show more crustal deformation and seismicity within the fore-arc than subduction of a smooth interface (scenario 1 and models without a seamount). Seismicity patterns are also affected by λ and C. A low λ results in shorter and shallower megathrust ruptures and higher cohesions decrease the recurrence interval. Furthermore, the seamount itself introduces more frequent nucleation of smaller events at its edge.