bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolution of the syn-orogenic sediment routing system in the North Pyrenean foreland basin - France
Authors: Al Reda Stéphane , Barbarand Jocelyn , Lasseur Eric , Briais Justine , Prieur Marine , Gautheron Cécile , Loget Nicolas , Lahfid Abdeltif
Published: March 2022

The North Pyrenean foreland basin evolved from underfilled to overfilled during the Eocene time in mirror of the development of the Pyrenean orogeny. The resulted Eocene syn-orogenic conglomerate series, known as “Poudingues de Palassou”, recorded the evolution of the mountain belt and the draining system. Three units are classically differentiated in the eastern part: the first and third units deposited during the late Ypresian – Lutetian and Priabonian times respectively, contain clasts from the Meso-Cenozoic regional sedimentary cover. A second unit deposited during the Bartonian corresponds to clasts of magmatic and metamorphic origin (including granites). The objective of this study is to identify the sources of the sediments and to reconstruct the drainage evolution during the Eocene. To this end, U/Pb zircon dating was carried out on granite clasts from Unit 2 and on the conglomerate matrix of the three units using laser ablation-ICP-MS. These analyses are coupled with sedimentary characterization of depositional environments, paleocurrent directions measured in the fluvial deposits and Raman analyses performed on black flysch clasts from the Unit 1/Unit 2 transition. The zircon U/Pb results show a dominance of Variscan ages (290-360 Ma) in the upper part of the Unit 1 and for the matrix of Unit 2 conglomerates. Granite clasts of Unit 2 show mostly ages between 324±2 and 335±1 Ma. For Unit 3, the age spectrum is broader, ranging from Variscan to Cadomian (290 – 600 Ma). Sedimentary analysis of units 1 and 2, show an increase of the amount of sediments and a greater alluvial system during the deposition of the unit 2. The Raman analyses on the black flysch show temperature peaks ranging from 495 to 587°C, comparable to those obtained in the eastern part of the North Pyrenean Zone (NPZ) on black flysch deposits. Interpretation of the results shows that the deposits of Unit 1 are mainly derived from the erosion of the Meso-Cenozoic cover of the NPZ in the Late Ypresian and Lutetian, ending with black flysch of the NPZ, followed by erosion of the Variscan massifs. For Unit 2, the deposition is accompanied by a change in the nature of the clasts and a widening of the depositional zone reflecting wider drainage area including the Axial Zone (AZ). For Unit 3, the broad spectrum of ages obtained, as well as the nature of the clasts, suggest a fairly large catchment area drained from the AZ and significant recycling from the actively deformed foreland sedimentary cover during Priabonian. This research work was financed and carried out as part of the BRGM-TOTAL source-to-sink program.
A critical evaluation of simple, flexible, and scalable models of daily transpiration in forested biomes
Authors: Bright Ryan M. , Miralles Diego G. , Poyatos Rafael , Eisner Stephanie
Published: March 2022

Transpiration (T) makes up the bulk of total evaporation over vegetated land yet remains challenging to predict at landscape-to-global scale.  Model improvements often occur at the expense of model parsimony and an increased dependence on input data that is difficult to acquire at large scale.  T models intended for these scales should ideally be easily scalable using routine meteorological and/or remote sensing data as input.  

Here, we critically evaluate several “big leaf”-type models ranging in their complexity to simulate daily T in a variety of forest biomes.  All these models use input data streams furnished by readily available global reanalysis or satellite-based remote sensing products.   We develop and evaluate a novel moisture stress method based on the Antecedent Precipitation Index (API) serving as proxy for soil moisture supply, motivated by the challenge of acquiring reliable soil moisture and other soil physical property data at large spatial and temporal scales.

We rely on independent estimates of T derived from co-located sap flow and eddy-covariance measurement systems.  The triple collocation technique is employed to quantify error metrics when treating modeled T as a third, independent measurement.

Preliminary results suggests that models that explicitly account for the aerodynamic coupling between canopy surfaces and the atmosphere generally perform better than those that do not, and that the API-based approach to modeling constraints related to soil moisture stress appears as a valid alternative when soil moisture information is unavailable.  
Developing Novel Geophysical Tools to Investigate Urban Vegetated Soil Moisture Dynamics
Authors: Thaman Narryn , Stirling Ross , Chambers Jonathan E.
Published: March 2022

Vegetation is an important tool for managing urban surface water and shallow geotechnical assets. However, root water uptake driven changes in slope hydrology (soil water content, matric suction, and hydraulic conductivity) are poorly understood in heterogeneous soils and under extreme climatic conditions. Slope stability is affected by intrinsic factors, including geometry, soil properties, groundwater and vegetation driven matric suction. Field evidence indicates that engineered slopes are susceptible to hydrometeorological slope instability mechanisms and that these pose a potential failure hazard to asset operation and public safety. The UK hosts 15,800 km of railway network and 7100 km of strategic road network, accounting for 49,000 slopes. This is a significant portfolio of slopes that must be managed and maintained at considerable expense.

To better understand the influence of vegetation on soil water dynamics in geotechnical infrastructure, Electrical Resistivity Tomography (ERT) is being used. ERT is a non-invasive tool for measuring and imaging subsurface soil moisture dynamics volumetrically. ERT can be used to quantitatively establish how the presence of roots influences transient soil moisture content and suction to assess the effectiveness of vegetation in managing slope hydrology and excess surface water issues in the built environment. This research aims to use 4-D ERT to determine the impact of vegetation on the hydrological behaviour of a high plasticity clay derived sub-soil used in the construction of infrastructure slopes in the southern half of the UK. Laboratory-scale experiments are underway at the UK National Green Infrastructure Facility, Newcastle, using a controlled environment chamber. A suite of soil columns is planted with vegetation, False Oat Grass (Arrhenatherum elatius) and Common Bent (Agrostis capillaris) and feature a 3D ERT electrode array and point sensors for measurement of volumetric water content, matric suction, and electrical conductivity throughout the profile. Through frequent imaging of soil-water-plant interactions and correlation with destructive root architecture imaging, this research aims to highlight how these relationships change over time and respond to extreme weather conditions (drought/inundation) to better predict, manage, and mitigate the occurrence of slope failure. Furthermore, the work aims to improve understanding of vegetation-driven soil moisture movement in the near-surface to better assess seasonal and longer-term slope stability to inform asset management strategies.
Permeability evoluation at the brittle to ductile transition in newberry volcano basalt
Authors: Violay Marie , Meyer Gabriel
Published: March 2022

Superhot Rock (SHR) geothermal projects (e.g., Japan Beyond-Brittle Project, Iceland Deep Drilling Project, and Newberry Volcano) seek to extract heat from geothermal reservoirs where water reaches a supercritical state (≥ 400 °C). Exploiting such a resource could multiply the electrical power delivered by geothermal wells by almost an order of magnitude. However, SHR reservoirs are hosted in semi-brittle to ductile rocks where fluid flow, porosity, permeability, and rock mechanics are still poorly understood. We conduct experiments in a newly designed, internally heated, gas-confining triaxial apparatus (located at EPFL, CH) where we deform reservoir-type samples under realistic SHR temperature, pressure, and strain rate conditions. Deep well core samples (40 x 20 mm) of andesitic basalts (porosities of 8–10%) from Newberry Volcano (US), were subjected to increasing confinement pressure (25–100 MPa) and temperature (20–500 °C) while continuously recording gas permeability via harmonic permeability. Additionally, triaxial deformation experiments were done at strain rates of 10-6 s-1, confinement up to 100 MPa, temperature up to 500 °C, and up to 8% strain while recording permeability. Results were compared with granite samples from Lanhelin (Fr.). Samples were ductile (e.g., no localization of strain) at relatively low pressure–low temperature conditions (100 MPa, 200 °C). Moreover, permeability in samples subjected to hydrostatic conditions rapidly decreased several orders of magnitude from an initial value of 5.10-20 m2 to less than 10-22 m2  at 50 MPa and 200 °C, effectively impermeable. Thus, permeability decreases rapidly in the ductile regime with strain to reach below measurable values at around 3% strain, and it remains so during subsequent semi-brittle flow up to 8% strain. We interpret this rapid decay of permeability as a result of the conjoined effect of ductile pore collapse and plastic deformation of the poorly crystalline matrix present in the sample. These insights further underline the need for advanced, sustainable reservoir engineering techniques in order to extract heat from high enthalpy geothermal reservoirs.
Determination of surface layer parameters at  a suburban area of Zagreb  in Croatia
Authors: Pandzic Kreso , Likso Tanja
Published: March 2022

Vertical wind and air temperature profile related parameters in the surface layer at the edge of a suburban area of Zagreb Capital in Croatia has been studied.  For that purpose, adopted Monin–Obukhov similarity theory and a comprehensive  Campbell Scientific Inc. observation system  of wind and air temperature at 2 and 10 m above ground, recorded since 2013, have been used. The results confirmed  estimation of effective roughness lengths dependent on eight wind direction sectors indicated before. Gratefully to that achievement,  a representativeness of wind data at standard 10-m height can be clarified more deeply for an area of at least about 1 km in upwind direction from the observation site which can be used in numerical weather prediction or atmospheric pollution modelling.
Automated prediction of wet-snow avalanche activity in Switzerland
Authors: Hendrick Martin , Techel Frank , Volpi Michele , Tasko Olevski , Pérez-Guillén Cristina , van Herwijnen Alec , Schweizer Jürg
Published: March 2022

Avalanche hazard forecasting is essential to reduce the risk for people and infrastructure in mountain areas. Among the different types of avalanches, wet-snow avalanches are particularly challenging to predict due to the poor understanding of their release mechanism. We therefore trained a random forest model to predict wet-snow avalanche activity based on weather and snow measurements and downstream SNOWPACK simulations provided by automated weather stations. The model was trained on a database covering 20 years of avalanche observations (avalanche type, size, location, slope aspect) in the context of operational avalanche forecasting in Switzerland. The prediction performance (F1-score: harmonic mean between recall and precision) for wet-snow avalanche active days is around 76% (recall: 73%, precision: 80%), and is 99% for days with no activity.  The model not only well reproduced the onset, but also the end of wet-snow avalanche periods. Operational testing during winter 2021-2022 allow to evaluate differences in model performance between nowcast derived from meteorological measurements and forecast from numerical weather prediction models. Overall, the results are promising and are an important step forward a more reliable forecast of wet-snow avalanche activity.
Understanding and reducing seasonal prediction errors of the ECMWF system in the tropical Indian Ocean
Authors: Mayer Michael , Alonso Balmaseda Magdalena , Johnson Stephanie
Published: March 2022

Accurate forecasts of tropical Indian Ocean variability are crucial for skilful predictions of climate anomalies on a range of spatial and temporal scales. Here we assess the ability of ECMWF’s operational monthly and seasonal prediction systems to represent variability in the Eastern Equatorial Indian Ocean (EEIO), an important center of action especially for the Indian Ocean Dipole (IOD) Mode. Strong air-sea coupling is present in this region. In ECMWF’s currently operational seasonal prediction system, this leads to rapid amplification of a weak cold bias of the oceanic initial conditions in the EEIO, resulting in too frequent occurrences of positive IOD events. Diagnostics show that this is related to winds in the EEIO exhibiting a biased relationship with local and remote sea surface temperatures when compared to reanalysis. The impact of the forecast bias in the EEIO on the skill of ENSO predictions via interbasin interactions is evaluated. We furthermore present results from numerical experiments with, i.a., changed atmospheric model physics and oceanic initial conditions which help to better understand causes of the diagnosed forecast errors as well as mechanisms of interbasin interaction, and provide guidance for model development.
Investigating compound flooding in Como
Authors: Banfi Fabiola , De Michele Carlo
Published: March 2022

Compound events are extreme events whose impact is enhanced by the synergy, in time and/or space, of multiple variables. An example of this typology of events is provided by compound flooding. In this case, the resulting flooded area is increased by several factors, combining together; for example, the contemporaneous occurrence of high sea level and heavy precipitation (multivariate event), the presence of high soil saturation prior to rainfall events (preconditioned event), a precipitation event affecting several basins (spatially compounding event), or a succession of precipitation events (temporally compounding event). In this respect, we have adopted a compound analysis to study a series of floods that affected the town of Como (Northern Italy). Indeed, the town experiences recurrent damages due to the flooding of the nearby lake. In particular, we collected and analyzed 53 flood events, covering the period 1981-2020, in order to gain a better and more in-depth understanding of the phenomenon. This may eventually have important implications for the prediction and risk reduction of compound flooding.
Studies on the active use of urban forest areas as pluvial flood prevention
Authors: Gürke Sebastian , Jensen Jürgen
Published: March 2022

In recent years, heavy rainfall events have caused significant damage in urban areas across Germany. Experiences in coping with pluvial floods show that single measures alone cannot reduce the risk, but the combination of different measures is required. Economic aspects and limited land availability in cities emphasize the demand for multifunctional and sustainable retention areas. In the ongoing research project WaldAktiv*, we investigate the integration of existing urban forest areas into municipal flood prevention. The idea is to direct parts of the surface stormwater run-off into urban forest areas for storage and infiltration to reduce flooding in built-up areas. As study area, we use the district of Siegen-Wittgenstein, which has a high vulnerability to pluvial flooding due to its low mountain range topography. At the same time, with an area share of 71%, it is the most densely forested district in Germany and thus particularly well suited to determine corresponding potentials. However, this aim and other positive synergy effects are countered by (ecological) risks, such as the possible entry of pollutants into the forest areas, which must be taken into account during the studies.

First, potential flow paths and terrain depressions are identified based on a digital elevation model using a topographic analysis. While flow paths are used to delineate the individual catchments, terrain depressions in the urban forest areas represent potential retention basins for stormwater run-off. Although many terrain depressions are found, the analyses show that they are rarely located in suitable areas, so that artificial retention basins may have to be created in certain forest areas. Using hydrological modelling, the capability of the forest soil in terms of infiltration is estimated based on various soil geodata sets. In order to model the measures and assess their effectiveness, hydrodynamic numerical modelling is performed for different rainfall scenarios. In this contribution, we will present methods and current findings of the research project.

* WaldAktiv is a research project, funded by the German Federal Ministry for the Environment, Nature Conservation, Nuclear Safety and Consumer Protection (BMUV) and the district of Siegen-Wittgenstein through the project management of Zukunft – Umwelt – Gesellschaft (ZUG) gGmbH under the grant number 67DAS179.
Eurasian wintertime cooling: New perspectives from an updated synthesis
Authors: Outten Stephen , Li Camille
Published: March 2022

Over a decade ago, researchers noticed that as the Arctic warmed rapidly, there was an apparent cooling over large areas of central Eurasia in the wintertime. Many theories were put forward suggesting that changes in wintertime sea-ice were linked to this observed cooling through some hereto unknown teleconnection. Numerous studies based on observations, reanalyses, and a vast array of modelling experiments have been undertaken to resolve this question. The ongoing debate regarding Arctic to mid-latitude teleconnections over the Eurasian sector has divided the scientific community, as highlighted by the work of Cohen et al. [2020], primarily between those in favour of sea-ice having a key role in giving rise to the cooling, and those who believe the cooling is primarily the result of internal atmospheric variability. While Eurasian cooling itself has mostly ended, the debate continues due to a desire to better understand the teleconnections underlying Northern Hemisphere climate variability.

Here we discuss a new synthesis study into Eurasian cooling, undertaken by an extensive team at the Bjerknes Centre over the past two years. The work breaks down the debate into a simple structure, examining first the findings of the observational-based studies and the modelling-based studies separately. In evaluating this body of literature, we attempt to avoid categorizing studies based on the researchers’ interpretations of their findings, and focus where possible on only the facts of what their analyses and simulations show. This has allowed us to reconcile some of the apparently conflicting results in the literature. To be clear, we do not present a new mechanistic understanding of the processes underlying Eurasian cooling. However, laying out the existing research in an objective and structured manner has allowed us to propose a new framework within which to view the problem, wherein we clarify the distinct roles of internal variability and an external (sea-ice driven) forcing of Eurasian cooling.
Landsat-1 mosaic of Antarctica from the 1970s
Authors: Miles Bertie , Bingham Rob
Published: March 2022

The Landsat-1 satellite provides sporadic coverage of coastal Antarctica between 1972 and 1975.  This dataset is a highly valuable scientific resource but has yet to be utilized to its full potential. The imagery are of reasonable quality and have a spatial resolution of 60 m, but are often difficult to process owing to their poor geolocation accuracy, where most images are displaced by >10 km. This requires a time-consuming manual correction which can be especially tricky over the featureless sections of the ice sheet (e.g. Ross Ice Shelf). Here we report on progress towards creating a geolocated mosaic over coastal Antarctica that preliminary analysis indicates will have near-complete coverage with only limited cloud cover. Potential glaciological uses for the mosaic include coastline change both in terms of fast flowing outlet glaciers and the slower flowing regions of the coastline, ice shelf damage, basal channel evolution and migration, changes in ice rises and also any changes in bedrock exposure. We highlight these potential uses with a few small-scale examples.
Anisotropy of the Bohemian Massif lower crust from ANT - VTI model or additional azimuthal variations?
Authors: Kvapil Jiří , Plomerová Jaroslava , Kampfová Exnerová Hana , Working Group the AlpArray
Published: March 2022

Transversely isotropic lower crust of the Bohemian Massif (BM) has been revealed by an ambient noise tomography (ANT) of the BM (Kvapil et al., Solid Earth 2021). The significant feature of this 3D vSV model is the low velocity layer in the lower part of the crust at depth between 18-30 km and the Moho. The upper interface is characterized by a velocity drop in the 1D velocity models retrieved by the ANT. The interface is interrupted around boundaries of major tectonic units of the BM. The lower interface (Moho) exhibits a sharp velocity increase at 26-40km depths through the massif.

In this work we test whether we are able to detect azimuthal anisotropy in the lower crust, approximated up to now by anisotropic VTI model. We use Rayleigh wave dispersion curves evaluated from station pairs sampling the BM in the period range sensitive to the lower crust. First, we analyze seasonal variations of noise sources and their effect on quality and repeatability of dispersion curve measurements. Then we remove the effect of local heterogeneities by subtraction of synthetic dispersion curves calculated for the 3D vSV model along each station-pair raypath. Retrieved variations of azimuthal anisotropy are period-dependent with the fast velocity directions around NE-SW. We interpret the lower crust anisotropy layer as an imprint of the Variscan orogenic processes such as the NW-SE shortening of the crust and the late-Variscan strike-slip movements along boundaries of the crustal unit recorded in the interruptions of velocity drop interface in zones where anisotropic fabric of the lower crust was modified or erased.
Environmental, economic and social sustainability of Alternate Wetting and Drying rice irrigation in Northern Italy
Authors: Gharsallah Olfa , Mayer Alice , Romani Marco , Ricciardelli Andrea , Caleca Sara , Rienzner Michele , Corsi Stefano , Ottaiano Giovanni , Gilardi Giulio , Facchi Arianna
Published: March 2022

Italy is the Europe’s leading rice producer, with over half of total European production. The main rice area is in the north-western part of the country (Lombardy and Piedmont regions). In this area, irrigation of rice has been traditionally carried out by flooding; the introduction of alternative water-saving irrigation strategies could reduce water consumption, but their overall environmental and economic sustainability, as well as their social acceptability, should be investigated.

An experimental platform was set up in the core of the Italian rice district (Lomellina, PV) to compare different rice irrigation management options: wet seeding and traditional flooding (WFL), dry seeding and delayed flooding (DFL), wet seeding and alternated wetting and drying (AWD). Six plots of about 20 m x 80 m each were set-up, with two replicates for each irrigation option. One out of two replicates for each option was instrumented with: water inflow and outflow meters, set of piezometers, set of tensiometers and water tubes for the irrigation management in the AWD plots. Proper agronomic practices were adopted for the three management options. Periodic measurements of crop biometric parameters (LAI, crop height, crop rooting depth) were performed and rice grain yields and quality (As and Cd in the grain) were determined. Data measured in the field, together with those provided by the farmer, concerning the agronomic inputs and the economic costs incurred for the three irrigation options, were used to assess their economic and environmental sustainability through a set of quantitative indicators. Finally, through interviews with rice growers of the area, barriers to the adoption of the AWD technique were assessed and ways of overcoming them identified. In order to support water management decisions and policies, data collected at the farm level are extrapolated to the irrigation district level through a semi-distributed agro-hydrological model, used to compare the overall irrigation efficiency achieved implementing AWD when compared to WFL.
Mid to Late Holocene East Antarctic ice-core tephrochronology: Implications for reconstructing volcanic eruptions and their impacts over the last 5,500 years
Authors: Abbott Peter , McConnell Joseph , Chellman Nathan , Kipfstuhl Sepp , Hörhold Maria , Freitag Johannes , Plunkett Gill , Sigl Michael
Published: March 2022

Ice cores are powerful archives for reconstructing volcanism and developing tephrochronological frameworks, as they can preserve both the soluble, i.e. aerosols, and non-soluble, i.e. tephra, products of volcanic eruptions. In addition, and particularly over Holocene timescales, high-precision annually resolved chronologies have been developed for these records and permit ages to be assigned to eruptions. The identification of tephra in ice cores in direct association with chemical indicators of volcanism, such as sulphate, can significantly enhance volcanic reconstructions as tephra can be linked to an eruptive source. Such source attributions can provide information on the location of the eruptions, the magnitude of aerosol emissions at the source and help assess any climatic impact. In addition, they can aid the reconstruction of volcanic histories and the assessment of future hazard risk.  

 

The tephra record for the interior of East Antarctica over the last 5,500 years is potentially underexploited as a prior focus on visible horizons and exploring the deep ice cores that cover longer time spans has resulted in only one horizon, dated to ~3.5 ka BP, being identified in these records. Here we discuss ongoing tephrochronological investigations of two ice-cores, B53 and B54, retrieved from the interior of the East Antarctic Plateau. High-resolution, sub-annual chemical records have been measured from both cores using a continuous melter system. These data were used to develop a sampling strategy to identify cryptotephra horizons with ice-core sections containing coeval peaks in fine insoluble particles and non-sea-salt sulphur targeted and >50 events were directly sampled. This approach recently has been used to identify cryptotephras in both Greenland and Antarctic ice cores. When glass tephra shards were identified thin sections were created and individual glass shards were geochemically analysed using electron-probe microanalysis to help identify their volcanic source and permit correlations between records.

 

Thus far, more than 10 cryptotephra horizons have been identified and linked to regional sources such as the South Sandwich and South Shetland Islands and the ~3.5 ka BP event has been traced in both cores as a visible layer. More detailed investigations are being conducted on samples from specific volcanic signals of interest that may derive from eruptions of ultra-distal volcanic sources. Such eruptions could have deposited very small glass tephra shards over Antarctica, which poses significant analytical challenges and necessitates the use of innovative approaches for tephra identification and geochemical analysis.
Land and atmospheric conditions regulating urban heat and dry islands and their impact on convective cloud formation
Authors: Chiu Clinton T.F. , Wang Kai , Paschalis Athanasios , Erfani Tohid , Peleg Nadav , Fatichi Simone , Theeuwes Natalie , Manoli Gabriele
Published: March 2022

Urbanization modifies heat, moisture and energy budgets at the land surface, resulting in significant urban-rural differences. A consequence of land conversion to the built environment is the higher air and surface temperatures in cities compared to their rural surroundings, the so-called urban heat island (UHI) effect.  A few studies have also analysed the impact of cities on atmospheric humidity, the so-called urban dry island (UDI) effect, and observational evidence have revealed enhanced cloud cover and intensified rainfall events over large metropolitan areas. However, the impact of UHI and UDI on convection triggering is still a matter of enquiry. The understanding of how urban-induced change in the surface energy budget affects the diurnal evolution of the boundary layer temperature and humidity profiles is crucial to investigate the formation of convective clouds over cities.

We propose an analytical zero-order model of the Atmospheric Boundary Layer (ABL) to quantify the impact of surface and free atmosphere conditions on UHI, UDI, and convection triggering. The model is shown to reproduce field observations from the BUBBLE experiment in Basel (Switzerland) and is used to investigate the crossing between the ABL height and the lifting condensation level (LCL) as a proxy for the triggering of convective clouds. Our results confirm that urban areas are generally warmer and drier compared to rural counterparts, thus increasing both ABL and LCL heights. There is a range of free atmosphere conditions for which changes in urban imperviousness can impact convection triggering but surface warming alone cannot explain the observed enhancement of cloud cover over cities.
DUACS DT2021: 28 years of reprocessed sea level altimetry products
Authors: Faugère Yannice , Taburet Guillaume , Ballarotta Maxime , Pujol Isabelle , Legeais Jean Francois , Maillard Gwenola , Durand Chloe , Dagneau Quentin , Lievin Marine , Sanchez Roman Antonio , Dibarboure Gerald
Published: March 2022

For more than 23 years, the multisatellite DUACS system has been providing  high quality multi-mission altimetry Sea Level products for oceanographic applications, climate forecasting centers, geophysics and biology communities. They consist in directly usable and easy to manipulate Level 3 (along-track cross-calibrated Sea Level Anomaly SLA) and Level 4 (multiple sensors merged gridded gap-free) products. Global and regional datasets (Arctic Ocean, European Seas ...) are available.

A full reprocessing of these products is carried out almost every 3 years, based on the state-of-the-art Level 2 to Level 4 algorithms. In Decembre 2021, a new version will be available within the Copernicus Marine Environment and Monitoring Service (CMEMS) and the Copernicus Climate Change Service (C3S)  covering 28 years of altimetric data (i.e. almost a century of cumulated data using 24 altimetric missions). This version benefits from major improvements associated with new altimeter and mapping standards.

Here, we report the first results of this DUACS DT2021 multi-mission reprocessing. We first describe the main steps of the altimeter production system. Then, we discuss the characteristics and limits of the different products (C3S, CMEMS) in order to help the ocean and climate communities on their optimal use for validation, assimilation activities and other scientific studies. Several comparisons with independent datasets (along-track, drifters, tide gauges) show that a significant improvement has been achieved at mesoscale with this new version: almost 20% of SLA error reduction at wavelengths [65, 500km] and around 10% of geostrophic currents error reduction compared to the previous version (DT2018). At decadal time scale, the trend of the global mean sea level has been estimated to 3.4 +/- 0.4 mm/yr. (90% Confidence Interval), in line with other estimates and previous reprocessing DUACS-DT2018. New altimeter corrections are also available for the users (internal waves, correction for the Topex-A instrumental drift, flag ice).
Effects of topographic coupling at core-mantle boundary in rotation and orientation changes of the Earth.
Authors: Dehant Véronique , Rekier Jeremy , Puica Mihaela , Folgueira Lopez Marta , Trihn Antony , Van Hoolst Tim
Published: March 2022

We study coupling mechanisms at the topographic core-mantle boundary (CMB) of the Earth in the frame of nutations and Length-of-Day (LOD) variations. The CMB topography is usually considered to have a smooth spherical or elliptical shape, however, in reality it is bumpy and there are mountains and valleys representing local height differences of the order of a kilometer. The existence of a topography induces inertial waves that need to be considered in the flow of the core. This is in addition to the Poincaré fluid motion when the nutations are computed and in addition to a relative rotation of the fluid opposite and of the same amplitude as that of the mantle for LOD variations. The additional pressure and the topographic torque depend on the shape of the CMB and can be related to the spherical harmonic coefficients of the CMB topography. We follow the philosophy of the computation of Wu and Wahr [Geophys. J. Int., 128(1), 18-42, 1997] and determine the coefficients of the velocity field in the core at the CMB in terms of the topography coefficients. We used an analytical approach instead of a numerical one. We confirm that some topography coefficients may enhance length-of-day variations and nutations at selected frequencies, and show that these increased rotation variations and nutations are due to resonance effects with inertial waves in the incremental core flow.
Integrated and process-based modeling of flow and transport in multi-compartment karst systems with thick vadose zones
Authors: Noffz Torsten , Kordilla Jannes , Kavousi Alireza , Reimann Thomas , Liedl Rudolf , Sauter Martin
Published: March 2022

The hydraulic characterization of karst systems remains a high challenge given their heterogeneous nature and large range of hydrogeological properties. In this study, a methodological approach is presented that demonstrates to what extent the temporal variation of spring signals, such as discharge rate, dissolved constituents and water temperature can be employed to characterize the karst system and to differentiate the individual contributions of the different physical compartments, as well as to derive hydraulic properties of the individual compartments by integrated inverse modelling of the spring signals.

Each compartment – (i) surface zone, (ii) vadose zone, and (iii) phreatic zone – imposes a complex transformation of the input signals (e.g., flow rate, temperature, concentration) that are routed through the whole system. However, numerical approaches to reproduce flow and transport dynamics in karst systems often lack the physical representation of controlling processes (e.g., preferential flow dynamics in the vadose zone) and therefore struggle to provide unique solutions. Therefore, this study aims at the identification of parameter sensitivities and hence reduction of model uncertainty employing an integrated approach for the modeling of karst systems. In test scenarios artificial rain events deal as model input for the Precipitation Runoff Modeling System (PRMS) coupled to a dual-domain type vadose zone and discrete karst conduit network system embedded in a porous matrix within the phreatic zone in order to account for fast and slow flow components in each compartment. In the vadose zone diffuse flow through the porous matrix is modeled by standard bulk effective approaches (MODFLOW UZF or simple transfer functions) and rapid fluxes via preferential flow paths are represented by a source-responsive infiltration model governed by film flow dynamics. In the phreatic zone diffuse and conduit flow are represented by a discrete-continuum model (MODFLOW CFPv2). The model geometry is kept simple (i.e., one model layer and a single conduit connecting a single sinkhole with the spring) while vadose zone properties (e.g., overall thickness) and input signals are altered to focus on their impact on the flow signal and on the sensitivity of parameters.
Exploring macroscopic properties of soil organic matter using modeling and molecular simulations
Authors: Petrov Drazen , Escalona Yerko , Galicia Edgar , Tunega Daniel , Gerzabek Martin , Oostenbrink Chris
Published: March 2022

Soil Organic Matter (SOM) is composed of a complex and heterogeneous mixture of organic compounds. It is of great importance to understand its molecular structure, the conformations and water accessibility, as well as the interfaces and reactivity of SOM with its surrounding. SOM extracts permitted for decades a systematic way of studying SOM via the use of standardized samples.  We used such standardized samples of the International Humic Substances Society (IHSS) to computationally explore the properties of SOM.

We used the Vienna Soil Organic Matter Modeler 2 (VSOMM2; Escalona et al. (2021); https://somm.boku.ac.at/) to produce representative, condensed-phase, atomistic models of IHSS samples. This online tool ensures greater chemical diversity of the models and reproduces the carbon distribution or organic composition estimated by NMR. Generated atomistic models were subjected to molecular dynamics simulations. We characterized these systems in order to observe differences in their structure and dynamics.

Our results indicate the importance of carboxyl and aromatic groups in the molecular interactions, specifically for their interactions with cations and indirectly for their aggregation properties. We also investigated the sorption properties of these systems by calculating the free energy of absorption of inserting a water molecule to the system, which values were affected by the water content, compaction and phases of the organic matter.

These investigations help improve our understanding of properties and behavior of soil organic matter at a molecular level that is not attainable to experiments. We hope that such studies will have a great impact on basic research involving SOM.
Evaluating the fate of UV filters and transformation products during managed aquifer recharge: the role of reactive barriers, biofilms and varying redox. 
Authors: Jou-Claus Sonia , Rodríguez-Escales Paula , Martínez-Landa Lurdes , Diaz-Cruz M. Silvia , Carrera Jesús , Sunyer-Caldú Adrià , Quintana Gerard , Valhondo Cristina
Published: March 2022

Ultraviolet filters (UVFs) are emerging organic contaminants that are present in personal care (sunscreens and many cosmetics) and numerous industrial products. Among UVFs, the group of benzophenone derivatives are the most used worldwide. Benzophenone-3 (PB-3, oxybenzone) is one of the most common UVF. BP-3 is considered as an endocrine disruptor with estrogenic activity, it is photo-stable, lipophilic and bioaccumulates in different organisms. The widespread use of BP-3 has led to its release into aquatic ecosystems mainly via discharge of wastewater treatment plant effluents. Common sources of water for Managed Aquifer Recharge (MAR) are affected, to some extent, by effluents of wastewater treatment plants and therefore, MAR has been proposed as a potential source of these compounds to the environment. Understanding the fate of UVFs but also of their transformation products (TPs) in MAR is relevant because some of them can be more ecotoxic than the parent compound. We evaluated the fate of selected UVFs and its TPs at different compartments (water, soil and biofilm) in two field pilot scale MAR systems; one of them operated with a permeable reactive barrier based on compost and the other with sand (without reactive barrier). We compared the temporal and spatial evolution of these UVFs before and after a slug injection of lithium acetate, as organic carbon source, in the two MAR systems. Quantification of selected UVFs and TPs showed that the two MAR systems promoted the removal of UVFs. Extended removal was enhanced by the compost reactive barrier, in which lower concentrations of all selected UVFs and TPs were measured. The fact that they were detected and quantified more often sorbed onto the biofilm and organic fraction of sediment than in the aqueous phase suggested that degradation takes place in the two solid compartments.

 

Acknowledgements

This work was financially supported by the Catalan Research Project RESTORA (ACA210/18/00040), by the Spanish Ministry of Science and Innovation through MONOPOLIOS (RTI2018-101990-B-100, MINECO/FEDER) and Project CEX2018-000794-S), as well as the EU project MARADENTRO (PCI2019-103425 and PCI2019-103603). We also thank the Consorci de la Costa Brava Girona (CCBGi) for the unlimited access to the WWTP.
Reactive halogen chemistry in the Arctic boundary layer over snow during spring: A 1D modelling case study
Authors: Ahmed Shaddy , Thomas Jennie L. , Tuite Katie , Stutz Jochen , Flocke Frank , Orlando John J. , Hornbrook Rebecca S. , Apel Eric C. , Emmons Louisa K. , Helmig Detlev , Boylan Patrick , Huey L. Gregory , Hall Samuel R. , Ullmann Kirk , Cantrell Christopher A. , Fried Alan
Published: March 2022

Polar halogen chemistry has long been known to be active, especially in spring, and has an important influence on the lifetime of some volatile organics, ozone, and mercury. Reactive chlorine and bromine species, produced from snow and aerosols, can have significant impacts on the oxidative capacity of the polar boundary layer. However, halogen production mechanisms from snow remain highly uncertain, making it challenging to include descriptions of halogen snow emissions in models and to understand the impact on atmospheric chemistry. In this work, we investigate the role of Arctic chlorine and bromine emissions from snow on boundary layer oxidation processes using a one-dimensional atmospheric chemistry and transport model (PACT-1D). We explore the impact of halogen snow emissions and boundary layer dynamics on atmospheric chemistry by modelling primary emissions of Cl2 and Br2 from snow, and heterogeneous recycling reactions on snow and aerosols. We present a two-day case study from the 2009 Ocean-Atmosphere-Sea Ice-Snowpack (OASIS) campaign at Utqiagvik, Alaska. 

The model reproduces both the diurnal cycle and high quantity of Cl2 measured, along with the observed concentrations of Br2, BrO, and HOBr. Due to a combination of chemical emissions, recycling, vertical mixing, and atmospheric chemistry, reactive chlorine is confined to the lowest 15 m of the atmosphere, whilst bromine impacts chemistry up to the boundary layer height. Following the inclusion of halogen emissions and recycling, HOx concentrations (HOx = OH+HO2) increase by as much as a factor of 30 at the surface at mid-day. Consequently, volatile organic compound (VOC) lifetimes are significantly reduced within a shallow layer near the surface, due to chlorine atoms from Cl2 snow emissions and increased HOx attributable to halogen chemistry.
Impacts of post-photosynthetic fractionation on the carbon isotopic composition of leaf wax n-alkanes under elevated CO2
Authors: Warren Bridget , Bendle James , Yamoah Kweku Afrifa , Eley Yvette
Published: March 2022

The carbon isotopic composition of plant wax n-alkanes (δ13Cn-alkane) is a well-established proxy for bulk plant δ13C, which itself reflects plant community composition and palaeohydrology in the geologic record. Although the biosynthetic processes which form n-alkanes cause a depletion in 13C relative to bulk plant tissue, it is generally presumed that this depletion is constant. In particular, on geologic timescales bulk plant δ13C is invariant to changes in atmospheric CO2, and it is therefore assumed that δ13Cn-alkane follows the same pattern. However, this assumption has not been tested, and it is possible that the biosynthetic fractionation during the formation of n-alkanes and other lipid biomarkers is affected by atmospheric CO2 concentration independently of trends in bulk plant tissue. Here, I use the Birmingham Institute of Forest Research (BIFoR)’s Free Air Carbon Enrichment experiment (FACE) to investigate the impact of elevated CO2 on both bulk and n-alkane δ13C in order to identify any such influence of elevated CO2 on n-alkane isotopic composition. If any such effects are detected, CO2 levels should be accounted for in interpretations of deep-time δ13Cn-alkane records.
Meridional temperature gradients during the past 250 million years: Proxies versus Models
Authors: Wei Mengyu , Yang Jun , Hu Yongyun , Liu Yonggang , Li Xiang , Bao Xiujuan , Guo Jiaqi , Lan Jiawenjing , Li Zhibo , Lin Qifan , Man Kai , yin Zihan , Yuan Shuai
Published: March 2022

In this study, we investigate the meridional temperature gradients during the past 250 million years. We compare the differences between proxy data of oxygen isotopes and lithologic indicators and globally coupled atmosphere-ocean climate system model simulation results. Two climate models are employed, CESM1.2.2 and HadleyCM3. There are several significant differences between the model results and Scotese’s reconstruction and proxy data: 1) the tropical surface temperatures are usually higher in the model simulations than both Scotese’s reconstruction (Scotese 2016; Scotese et al. 2021) and proxy data (e.g., Huber and Caballero 2012, Song et al. 2019; Zhu et al. 2019), whereas the surface temperatures in high latitudes are usually lower; 2) the meridional temperature gradients in the model simulations are smaller in low latitudes but larger in the middle latitudes than Scotese’s reconstruction. These comparisons are helpful for paleoclimatology understanding and for future paleo-temperature reconstructions.
From ice crystals to climate: clearing high clouds of uncertainty
Authors: Gasparini Blaž , Voigt Aiko , Hartmann Dennis L. , Blossey Peter N.
Published: March 2022

The net radiative effects of tropical clouds are determined by the evolution of thick, freshly detrained anvil clouds that cool the climate into thin anvil clouds that warm the climate. To determine the role of these clouds in climate change it is important to understand how their microphysical and macrophysical properties control their radiative properties. We use cloud resolving model simulations to study the small-scale processes that drive anvil evolution and determine a delicate balance between thick and thin anvil clouds. Tiny differences in how ice crystals form, grow, shrink, or interact with solar or terrestrial radiation can lead to large differences in the climatic role of anvils. In this talk, we highlight the large impact of the interaction between radiation and ice crystal nucleation on the climatic properties of anvils. Such processes are currently not well represented in models used for climate projections. Therefore it is also not surprising that the uncertainty in tropical anvil cloud feedback is the dominant contributor to the total cloud feedback uncertainty. In addition, we show evidence that the high cloud feedback depends on the description of ice nucleation and the environmental amount of ice nucleating particles and cloud droplet number concentration.