bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetopause properties from global MHD numerical simulations, local Vlasov equilibrium models and in-situ observations
Authors: Echim Marius M. , Voitcu Gabriel , Munteanu Costel , Teodorescu Eliza
Published: February 2023

We derive the properties of the terrestrial magnetopause (MP) from two modelling approaches, one global-fluid/MHD, the other local-kinetic,  as well as from in-situ data analysis. We use global MHD simulations of the Earth’s magnetosphere (publicly available from NASA-CCMC) and local Vlasov equilibrium models (based on kinetic models for tangential discontinuities) to extract spatial profiles of the plasma and field across the Earth’s magnetopause. We use data from MMS spacecraft to probe in-situ the properties of the magnetopause. The experimental data also serve as a reference for comparing/validating the numerical simulations. The global MHD simulations use initial conditions in the solar wind extracted from OMNI database at time epoch when MMS crossed the magnetopause. The kinetic Vlasov model uses boundary conditions derived from the same in-situ MMS measurements upstream/downstream the MP. We find  the global MHD simulations generally locate the MP at distances of one Earth radius farther from the position observed by MMS. We also find an overestimation of  the  thickness of the MP by one order of magnitude, as well as of the plasma density in the vicinity of the magnetopause. The MP spatial scale derived from local Vlasov equilibrium is consistent with observations for three transition profiles (magnetic field, plasma density, plasma bulk velocity). The overestimation of the density in Vlasov equilibrium is reduced compared with global MHD solutions. We discuss our results in the context of future SMILE mission campaigns for observing the Earth’s magnetopause.
A 3D numerical model for chimney formation in sedimentary basins
Authors: Wangen Magnus , Wang Hongliang , Yarushina Viktoriya
Published: February 2023

We propose a 3D model for pipe and chimney formations in tight rocks in sedimentary basins. It is an adaption of a model for hydraulic fracturing in an anisotropic stress field by fluid injection (fracking). The trigger for chimney formation is high overpressure in permeable units, such as reservoirs or aquifers. The permeable units serve as a source of high-pressure fluid that drives the chimney formation. The numerical model is based on cells that “fracture” when the fluid pressure exceeds the least compressive stress and random rock strength. The locally highest points in the reservoir rock become the most likely places for chimney formation. Fracturing implies that cells have their permeability changed from their initial value to a value that represents an average permeability of an open fracture network. Chimney growth appears as chains of cells (branches) emanating from the base of the cap rock. These chains of cells grow towards the surface. The branches have an enhanced permeability during ascension because the fluid pressure in the fracture network is greater than the least compressive stress. The fluid pressure keeps the fracture network open. When the branches reach the hydrostatic surface, the fluid pressure drops below the least compressive stress and the fracture network closes. The model produces pipe structures and chimneys as accumulations of branches that reach the surface. The degree of random rock strength controls how pipe-like the chimneys become. The chimney, which is formed by branches of the fractured cells, drains the reservoir for overpressured fluid. Chimney formation stops when the overpressure in the reservoir is reduced below the least compressive stress at the base of the caprock. The fracture permeability of the chimney branches controls how many branches are produced, and thereby how wide the chimney becomes. A “low” permeability produces wide chimneys with many branches, and a “high” permeability gives narrow chimneys made of just a few branches. The model is demonstrated in a setting similar to the chimneys observed in the cap rock over the Utsira aquifer in the North Sea. By using the proposed model, the permeability of such chimneys is estimated to be of the order of 10 micro-Darcy.
Ecological Water Demand Estimations for Desert Terminal Lake Survival under Inland River Water Diversion Regulation
Authors: Li Lingqi
Published: February 2023

Desert terminal lakes are important signals to discern ecological degradation crises, partic- ularly in arid areas where an artificial project of ecological water diversion has designated a quota of river water to prevent lake body shrinkage and protect the ecosystem. Knowledge of the minimum ecological water demand (EWD) is thus necessary to ensure the basic health of lake ecosystems. This study analyzed the spatiotemporal evolution of water boundaries using Landsat satellites data via remote sensing technology from 2002 to 2017 in East Juyan Lake, an inland desert terminal lake of the Heihe River in northwest China. The minimum lake water demand was determined using two estimation methods: the lake-evaporation-oriented EWD method and the minimum water level method. In the latter method, both lake topography (using water-level area curves) and biological survival demands (using bighead carps as indicators) were considered to derive the minimum lake EWD. Water diversion to the lake over the past 15 years has increased the lake’s area, but there are still marked intra-annual seasonal variations. The annual minimum lake water demand was suggested to be 54 × 106 m3/year by comparing the different methods; however, it was not satisfied, and the lake survival was endangered when the occurrence frequency of the annual runoff in the Zhengyixia hydrological station exceeded 65%. This study offered promising directions for inland lake water resource management.
Combining global-scale atmospheric heat transport and synoptic-scale extratropical cyclone characteristics to understand the role of latent heating for midlatitude storm tracks
Authors: Zibell Jan , Schemm Sebastian , Hermoso Verger Alejandro
Published: February 2023

    Poleward atmospheric energy transport is determined by the overall equator-to-pole radiative imbalance. As this imbalance is projected to remain fairly constant in end-of-century greenhouse gas forcing scenarios, an increase in poleward latent heat transport must be accompanied by a reduction in dry static energy flux. Since midlatitude energy transport is dominated by the eddy component, changes in the energy budget go hand in hand with changes in cyclone characteristics. From a dynamical perspective, the enhanced condensation due to climate change promotes intensification, prolongs lifetime of cyclones, and can increase stationarity of anticyclones. However, it also tends to increase static stability and thereby reduce baroclinicity, which is another important driver of cyclone development. Additionally, baroclinicity is projected to increase at upper levels due to tropical amplification, to decrease at low levels as a result of Arctic amplification, and to be affected by land-sea temperature contrast changes. As these processes are at play simultaneously, isolating the role of moisture is rather complicated. Therefore, in addition to coupled climate model simulations we use idealized aquaplanet simulations to single out the effects of individual physical mechanisms and address the question: if the overall poleward energy transport remains largely unaffected by global warming, how do cyclone characteristics change in the presence of increased moisture in the atmosphere?    For bridging the gap between the global energy flux and synoptic-scale features, we analyse the role of increasing moisture for shaping midlatitude storm tracks in present and future climates from both an Eulerian and a Lagrangian perspective. We apply the moist static energy (MSE) framework that allows partitioning atmospheric energy fluxes into eddy and mean, dry and moist components. Here, eddies are related to cyclones and anticyclones, while the mean energy flux is associated with planetary waves and the mean meridional overturning circulation. The goal is to relate the eddy MSE fluxes to feature-based results including extratropical cyclone number, lifetime, intensity, location, and tilt. By combining results from both global-scale eddy energy fluxes and synoptic-scale feature quantities, we aim to improve the understanding of the role of latent heating in shaping the mean properties of extratropical storm tracks. Therefore, a central question of this project is whether and how changes in cyclone quantities can be linked to changes in latent heat transport and release. Building on what we learn from bringing the two perspectives together, we will proceed to investigating the impact of increased latent heating on midlatitude storm tracks. 
Feedbacks between large-scale vegetation restoration and regional precipitation over the Chinese Loess Plateau
Authors: Zhang Baoqing , Tian Lei
Published: February 2023

Large-scale anthropogenic revegetation has considerable climate, carbon, and ecosystem benefits by affecting ecohydrological and hydrometeorological processes. Previous studies have pointed out that large-scale vegetation restoration in non-humid areas significantly increases evapotranspiration (ET), resulting in the reduction of soil moisture and streamflow. However, the impact of vegetation-climate feedback on water balance was ignored in these studies. The Loess Plateau (LP) in China has the largest vegetation restoration area in the world since 1999. Here, we combined in-situ hydro-meteorological observation and coupled land-atmosphere model to analyze how vegetation reconstruction affects the water resource budget of the LP. Two simulation experiments were designed to achieve a quantitative evaluation, including a real scenario that reflects the actual vegetation restoration, and a hypothetical scenario without vegetation restoration. The net impact of vegetation restoration on local precipitation can be analyzed by comparing the two scenarios. We quantified the feedback effect of vegetation restoration on local precipitation and the underlying mechanisms. The observation results show that precipitation increased on the LP after the restoration, and the surface water production in most areas on the LP (82.3%) shows a strong robust growth trend (2.76 mm yr-2), although the ET has increased at the same time. Our simulations show that the annual average precipitation under the vegetation restoration scenario on the Loess Plateau is 12.4% higher than the non-vegetation restoration scenario. We found the enhancement of land-atmosphere interaction is a main reason for the rapid growth of precipitation. Such an enhancement is caused by vegetation restoration that greatly accelerates the local water cycle. The contribution of large-scale vegetation restoration to precipitation increase is about 37.4%. Our research emphasizes the importance of considering vegetation-climate feedback when assessing the impact of large-scale vegetation restoration and will provide guidance and theoretical support for ecological protection and sustainable vegetation restoration in water-scarce regions.  
Impact of Model Resolution on Mixing and Dispersion in the Gulf of Mexico
Authors: Ntaganou Nektaria , Chassignet Eric , Bozec Alexandra
Published: February 2023

We investigate the importance of model resolution in identifying the nature of mixing and dispersion in the Gulf of Mexico, by comparing two data-assimilative, high-resolution simulations, one of which is submesoscale-resolving. By employing both Eulerian and Lagrangian metrics, upper-ocean differences between the mesoscale- and submesoscale-resolving simulations are examined. Focusing on regions characterized by high submesoscale activity, we approach the notion of mixing by tracking the generation of Lagrangian Coherent Structures (LCSs) and transport barriers. Finite-time Lyapunov exponents (FTLE) fields reveal higher separation rates of fluid particles in the submesoscale-resolving case which indicates more vigorous mixing. Using probability density functions (PDFs), the extent of mixing homogeneity is also explored, with preliminary results suggesting that mixing is more homogeneous in the submesosclae-resolving case. Finally, we aim to identify regions of convergence in the areas of interest by advecting passive tracers that tend to organize themselves along attracting LCSs. Applications of passive tracer advection are then translated to extreme event situations, such as the Deepwater Horizon.  
Total Solar Irradiance and Terrestrial Outgoing Longwave Radiation Measurements obtained with CLARA onboard NorSat-
Authors: Haberreiter Margit , Finsterle Wolfgang , Montillet Jean-Philippe , Gyo Manfred , Pfiffner Dany , Mostad Martin , Spydevold Ivar , Beattie Alex , Andersen Bo , Schmutz Werner
Published: February 2023

The Earth Radiation Budget at the Top of the Atmosphere (ToA) governs the status of climate change on our planet. The ERB is the balance between the incoming Total Solar Irradiance (TSI) and total outgoing radiation at the ToA. If more energy is stored in the system the Earth Energy Imbalance is positive and the temperature in the system rises. The Compact Lightweight Absolute RAdiometer (CLARA) experiment onboard the Norwegian micro satellite NorSat-1 is an SI traceable radiometer with the primary science goal to measure TSI from space. Besides TSI, CLARA also measures the terrestrial Outgoing Longwave Radiation (OLR) at the ToA on the night side of Earth. We present the latest status of the data and degradation correction obtained with this SI-traceable radiometer and compare the CLARA TSI and OLR time series with other available observations and reanalysis data. The validation of these measurements is key to advance our capability to determine the Earth Energy Imbalance from space. 
Automatically dunes mapping and morphometric analysis using Artificial Intelligence
Authors: Daynac Jimmy , Bessin Paul , Pochat Stéphane , Mourgues Régis
Published: February 2023

The surface of some planet’s present abundant periodic topographic forms at different scales (mm- km) and in different environments. They are called bedforms and develop at the interface between a moving fluid and a deformable and/or erodible material. Sand dunes are major bedforms in aeolian systems and play an important role in understanding how aeolian environments evolve. Generally grouped in dune fields, their morphological characteristics (e.g. shape, size, patterns of spatial organization) play a critical role understanding how aeolian environments evolve and interact with global changes. Detailed maps of these morphologies are produced by GIS manual digitizing from high-resolution satellite imagery and digital terrain models but this approach remains time-consuming. One way to override these locks is to use Artificial Intelligence (AI) to increase the computational speed, accuracy and reproducibility of mapping.We here present a GIS automated mapping protocol of aeolian bedforms contours and crestlines based on AI. First, we extract the Residual Relief in order to delete the regional topographic trend and map the different dune generations. Secondly, an unsupervised pixel-based classificator (Deep Learning, U-Net CNN) trained with Residual Relief samples of different dune forms is used to detect and map dunes independently of the bedrock. Thirdly, the dune crests are skeletonized from the identification of high inflection point of the dunes from a Volumetric Obscurance approach. The protocol is repeated for each dune order of magnitude to extract the different superimposed generations of dunes and their relationships.To illustrate its performance, the protocol was applied on a part of the Rub’Al Khali (220,000 km²) and Namib deserts (115,000 km²) to map the various dune forms and a first morphometric analysis is realized at the scale of the two sand seas. We produced a detailed map of the aeolian morphologies for each desert at two orders of magnitude (kilometer-scale and hectometer-scale dunes). For the Rub’Al Khali desert, more than 78,000 dunes (58,000 km²) and crestlines were mapped in 6 hours of processing and more than 17,000 dunes (12,000 km²) and crestlines for the Namib desert in the same processing time. The first morphometric parameters calculated from the previous results show a spatial variability of the length, width, height and crests orientation for Rub’Al Khali and Namib dunes. Thus, the protocol contributes to provide a digital atlas of the different dune generations (kilometer-scale and hectometer-scale dunes). All of these results allow to visualize the morphological dunes diversity and contribute to understand the relationships between forms and processes at a dune field scale.
Parametrization of dust storms in the Sahel by cold pools
Authors: Thiam Mamadou Lamine , Hourdin Frédéric , Grandpeix Jean-Yves , Rio Catherine , Gaye Amadou Thierno
Published: February 2023

The cold pools, created below cumulonimbus from the evaporation of precipitation, generate the strong winds responsible for the large dust storms called “haboobs” which appear in the Sahel in summer. Most global climate models do not take into account these types of dust emissions due to lack of parameterization of cold pools and associated gusts (Marsham et al. 2011 ; Pantillon et al. 2015). The introduction of a parameterization of cold pools in the LMDZ climate model has improved the representation of convection, and in particular of the diurnal cycle of continental precipitation in the tropics (Rio et al. 2009). The aim of this work is to develop a parameterization of gusts related to cold pools in order to take into account ‘‘hoobobs’’ in LMDZ model. To do this, we use Large Eddy Simulations (LES) performed on an oceanic domain and in Radiative-Convective Equilibrium (RCE) mode. We use a LES of an oceanic RCE case, easier to analyze because the temperatures are uniform on the surface and therefore the cold pools easier to detect. Before developing a gust parameterization, we evaluate the cold pools parameterization in LMDZ on this RCE case, which has never been done so far. If the comparison confirms the relevance of the scheme and its qualitative match to the LES behavior, is also led to substantial improvements and adjustments to this scheme. Next, we analyze the wind distributions in the LES in order to construct a parametrization based on a probability distibution function of the subgrid scale distribution of the wind which will allow us to take into account the effect of gusts on dust storms. The parametrization relates the moments of the distribution to large-scale wind speed, the spreading speed of the cold pools and the surface fraction covered by the latter. In the following, we will test the parametrization on the LMDZ model by focusing on dust storms in the Sahel during the rainy season.
Releasing sediments while reconnecting rivers: how do channels respond and how long does it take?
Authors: Collins Mathias , Baker Matthew , Cashman Matthew , Miller Andrew , Van Ryswick Stephen
Published: February 2023

Sediment management is an important aspect of river reconnection projects, often driving costs and influencing community acceptance. At sites with uncontaminated sediments, downstream release is an attractive option because it is often the cheapest and most practical approach and the sediment can be ecologically beneficial to downstream areas deprived of it for years by the dam. To employ this option, project proponents must estimate the sediment quantity to be released and, if substantial, estimate how long it will take to erode, where it will go, and how long it will stay there. We investigated these issues for sediments released by the 2018 removal of Bloede Dam on the Patapsco River in Maryland, USA. The dam was about 10 m high and its impoundment filled with sand and mud. Taking the surface elevations of these sediments surveyed immediately before removal and subtracting estimates of the pre-dam valley elevations derived from 21 cores and post-removal surveys of exhumed pre-dam surfaces, we estimate there was approximately 186,600 m3 of stored sediment composed of 70% sand and 30% mud. These proportions match estimates made during pre-removal engineering studies, but our total stored sediment estimate is about 20% less. The difference between estimates reflects a real change in stored sediment quantity between 2018 and 2012 when the engineering studies were completed, additional data available to us after removal, and different estimation methods. After removal, using elevation surveys generated by traditional methods as well as UAS-based aerial imagery and structure-from-motion (SfM) at high temporal resolution, we documented rapid erosion of the stored sediments in the first six months (~60%) followed by greatly reduced erosion rates for the next couple of years. A stable channel was developed in the impoundment during the rapid erosion phase. These results are similar to a two-phased erosion response reported for sediment releases at dam removals around the world across a range of dam and watershed scales, indicating what practitioners and communities should expect when reconnecting rivers in similar settings. Downstream, repeat surveys combined with discharge and sediment gaging show rapid transport of eroded sediments through a 5 km reach, especially during the first year when discharges were above normal, and little overbank storage.
Evidence of Late Cenozoic transpressive reactivation of an inherited strike-slip fault system and its influence in drainage reorganization in the Longitudinal Valley of Northernmost Chile
Authors: Vega Ruiz Ambrosio , Victor Pia , Pena-Castellnou Sara , Reicherter Klaus , Binnie Ariane , Binnie Steven
Published: February 2023

The Longitudinal Valley in Northernmost Chile was the main depocenter of widespread fluvial-alluvial systems active through the Neogene. These formed extensive lacustrine systems located at the eastern slope of the Coastal Cordillera until exorheic drainages developed between Arica and Pisagua (~18°30’S – 19°30’S) ca. 3 Ma ago. The top surfaces of the continental deposits form a regional scale pediplain (Pacific Paleosurface), where run-off is focused in present-day perennial streams draining to the Pacific Ocean through deeply incised quebradas. Some geomorphic and climatic constraints and suggestions exist regarding how the uplift of the Coastal Cordillera and the western Andes influence the shift in drainage regimes. However, little is known about how tectonic activity across this region affected landscape evolution since the structural architecture is difficult to unravel in this area of high sedimentation but low displacement rates.We performed an exhaustive regional mapping of structural and geomorphic evidences of fault activity and drainage patterns based on high-resolution DEMs, satellite, and UAV imagery data, as the long-term hyperaridity of this area leads to well-preserved landforms and lack of vegetation cover. Our investigations reveal evidence of a reactivated complex inherited strike-slip system across the Longitudinal Valley, deforming Miocene to Quaternary surfaces. Local growth strata, angular unconformities, and flower structures within the Late Miocene to Early Pliocene lacustrine deposits suggest syn-sedimentary and dextral transpressional faulting near the boundary between the Longitudinal Valley and Coastal Cordillera. Importantly, we observe that large drainage reorganization patterns can be triggered by only little displacement along often blind fault structures, creating sufficient topography that cannot be surpassed by drainage incision in this hyperarid setting.The interpretation of a reprocessed ENAP seismic section at ~19°20’S, suggests that this fault system consists of inherited Mesozoic inverted structures deforming Oligocene to Late Miocene strata. Furthermore, progressive abandonment and deformed terraces of low-incised rivers crossing compressive structures suggest that these were active during the Quaternary, most probably ongoing until the recent past. New dating of deformed marker horizons will bring further insights regarding key parameters of fault activity for the Late Cenozoic and Quaternary.
Towards a GPU based particle model for streamer discharges
Authors: Fangel-Lloyd Elloïse , Dujko Saša , Karlsson Sven , Gammelmark Matthias , Rydahl Anton , Nishikawa Kenishi , Köhn Christoph
Published: February 2023

Terrestrial gamma-ray flashes (TGFs), bursts of X- and gamma-rays, are emitted from thunderstorms and are produced through relativistic electrons through the Bremsstrahlung process. Despite recent progress through measurements and simulations, the specific mechanism of electron acceleration remains unknown. As the processes inside thunderclouds occur on a multiscale level, we need to develop models that cover a wide range of temporal and spatial scales. As a first step, we here present a GPU based Monte Carlo particle-in-cell code to simulate electron avalanches and streamers, benchmarked against existing particle models. We will present this benchmarking as well as details on the GPU-code implementation as well as first results of electron avalanches and streamers and compare runtimes with previous models. This code will form the basis for a fully hybrid code running on the newest generation of pre-exascale computers. In the future, such a code will allow us to gain insight on the mechanisms responsible for TGFs.
Objective assessment of storm surge risk in the German Bight – historical events and future climate change
Authors: Schaffer Laura , Becker Nico , Schenk Ludwig , Hinrichs Claudia , Ditzinger Gabriel , Schade Nils H. , Befort Daniel J. , Kruschke Tim
Published: February 2023

Storm surges in the German Bight can have great destructive potential. This includes devastating floods, structural damage to infrastructure, and even loss of life. The most important driver of storm surge events in the German Bight is strong winds from north-westerly directions, often related to intense extra-tropical cyclones travelling from the North Atlantic into the North Sea region.Making use of an objective, impact-oriented identification and tracking scheme, we analyse storm events related to storm surges in the German Bight. This particular version of the tracking algorithm includes the so-called Storm Surge Severity Index (SSSI) and is used as a complementary tool in operational forecasting by the German Federal Maritime and Hydrographic Agency (BSH). The SSSI takes wind speed and direction into account and intends to quantify storm surge risk in the German Bight. However, to date, the SSSI has never been systematically evaluated for past storm surge events. To fill this gap and to prove that the SSSI can be used as a proxy for storm surge risk, we analyse the relationship between SSSI values of past storm events and the associated water levels recorded in the German Bight using ERA5 atmospheric reanalysis data. Moreover, we analyse potentially storm surge-relevant storms in a multi-model ensemble of global climate model simulations to assess potential future changes in storm surge risk in the German Bight.
Cryosphere and sea level rise : A numerical interactive educational activity
Authors: Foucher Clémence , Chapuis Anne , Durand Gaël , Barré Jean-Baptiste , Bataille Amélie
Published: February 2023

Expedition Sea Level - a time travel to unveil the mysteries of sea level rise : becoming an actor of climate change is a numerical interactive activity designed as a game for middle school students (11 - 15 years old) to learn the links between sea level rise, the melt of glaciers and ice sheets, and human activities. This includes various notions to help them understand why sea level changes, how ice sheets and glaciers evolve and are studied, the ideas of uncertain futures, mitigation and adaptation.This activity is to be discovered in group or alone, in class or in scientific facilities when classes come to visit and encounter the actors and actresses of science. Another of its goal is to create discussions and debates among students on various subjects regarding climate change but also to help them understand the scientific processes behind the different changes happening or incoming, in order to fight increasing eco-anxiety.To do so, a fictional narrative is decomposed in three chapters with a growing immersion for the audience. The first one is a short animation staging a young Maldivian girl in 2081, going to see her grandparents whom house is partially underwater. The second one is designed as a first person shooter game where the public plays a glaciologist at Dumont d’Urville and on the Astrolabe glacier, answering pedagogical quizzes and learning through mini games. And the last one is shaped as a multiple choices tree game, leading to three IPCC scenario (low, intermediary and high). The choices made by the player.s lead to one out of the three scenario in which the public needs to find the best adaptation plan to protect the grandparents from the first chapter.Expedition Sea Level is the result of a diploma project conducted alongside the european research project PROTECT. This fully illustrated project answers the communication needs of PROTECT but also the needs of understanding and entertainment expectations of middle school students, based on an anonymous survey conducted among 71 middle school students, mainland France, from December 2021 to February 2022.
PostMinQuake: analysis of post-mining induced micro-seismicity in former European hard coal regions.
Authors: Primo Doncel Paloma , Rudolph Tobias , Möllerherm Stefan
Published: February 2023

Underground mining operations, in which large amounts of rock are extracted, can induce seismic events. Furthermore, draining the water to prevent it from flowing into the mining works is necessary for hard coal mines. Once mining stops, the pumping rates of groundwater decrease or is no longer necessary, allowing the water level to return to its state prior to the construction of such mines. During the post-mining phase in hard coal regions, induced micro-seismicity represents a risk for future land use. The EU-PostMinQuake project, funded by the Research Fund for Coal and Steel (RFCS), aims to study the dependency of such events and the rising water table in hard coal basins to detect and manage the risks of post-mining seismicity. This contribution shows the relation between water and seismicity in four former underground hard coal mines located in Czech Republic, France, Germany and Poland.
A new regional model of the Subpolar Gyre based on NEMO4
Authors: Verezemskaya Polina , Barnier Bernard , Gulev Sergey , Molines Jean-Marc , Gavrikov Alexander , Lellouche Jean-Michel , Verezemskaya Alexandra
Published: February 2023

The investigation is devoted to the development of a regional eddy-resolving model of the ocean of the Subpolar North Atlantic in order to reliably reproduce the components and properties of the Subpolar Gyre and the Atlantic meridional overturning circulation. Using the tools of the NEMO4 model, a configuration was created and, based on the literature, new parametrizations were proposed and implemented in the model: correction of the friction stress (current feedback for forced models), cool skin and warm sublayer in surface turbilent fluxes scheme. Also we formulated the best scheme of horizontal impulse advection from the point of view of reproducing mesoscale vortices. Last but noe least the local-sigma coordinate was implemented in the area of underwater cascading (overflow). For the first time, the eddy-resolving global ocean reanalysis GLORYS12V1 was validated against the independent observational data. The implementation of the local sigma coordinate allowed to reproduce the flow function of the Atlantic meridional overturning circulation in a model with a stepped representation of bathymetry. All the parametrization and scheme innovations led to an improvement in the solution, with the exception of the cool skin parametrization. Physical processes representation in the model is discussed. 
Probabilistic estimation of postseismic relaxation parameters and processes following the 2011 Tohoku earthquake
Authors: Marsman Celine , Vossepoel Femke , van Dinther Ylona , D'Acquisto Mario , Govers Rob
Published: February 2023

Geodetic observations of 3-component surface motions following a megathrust earthquake are key to a better understanding of features and processes controlling the dynamics at subduction margins. The relative contributions of dominant drivers during the postseismic phase, such as viscoelastic relaxation, afterslip, and relocking, remain difficult to estimate individually and are often derived at the end of an observation period, without showing the temporal evolution of the processes. Data assimilation combines physical models with observations, and can be a way to constrain these contributions by estimation of model parameters, the associated uncertainties, and identifying parameter tradeoffs. We use Bayesian inference in the form of an ensemble smoother to estimate geodynamic parameters during the postseismic phase of the megathrust earthquake cycle. The ensemble smoother uses a Monte Carlo approach to represent the probability density distribution (pdf) of model states with a finite number of realizations. Prior estimates of the imperfect physical model are combined with the likelihood of noisy observations to estimate the posterior pdf of model parameters. We first discuss a synthetic data experiment where observations are sampled from a 3D earthquake cycle model and where we added variable levels of noise. We assimilate 3-component surface displacements into a 2D finite element viscoelastic earthquake cycle model. We incorporate an a priori heterogeneous temperature field to estimate the asthenospheric viscosity distribution through power-law parameters (e.g., stress power). Preliminary results show that model parameters, such as the extent of the cold nose, maximum depth of afterslip, and power-law parameters can be recovered remarkably well by assimilating synthetic on- and offshore surface observations. We show preliminary results of data assimilation of postseismic surface displacements following the 2011 Tohoku earthquake.
Modelling momentum transport in climate simulations of boundary-layer winds with a higher order parameterization scheme
Authors: Gentile Emanuele Silvio , Zhao Ming , Larson Vince , Zarzycki Colin
Published: February 2023

Accurate modelling of sub-grid momentum flux is crucial for reliable climate simulations of the boundary-layer wind. While first-order momentum flux parametrizations often employed in leading climate models are crude, consisting in a downgradient diffusion scheme with a separate cumulus momentum transport scheme, higher-order turbulence parametrizations which directly prognose the momentum flux are more flexible and general, adhering more closely to the governing equations.Here, we present the results of studying the sensitivity of the AM4-GFDL global climate simulations of the boundary-layer wind to a first-order, diagnostic, and a higher-order, prognostic, sub-grid momentum flux parametrization. Moreover, we demonstrate how the boundary-layer wind turning angle can be effectively used as a metric to evaluate the impact of changing the sub-grid momentum flux parametrization on the boundary-layer wind structure. 
Transformation of a low-relief periglacial landscape during the Mid Pleistocene Transition revealed by cosmogenic Krypton
Authors: Dunai Tibor J. , Binnie Steven A.
Published: February 2023

The Early to Mid-Pleistocene Transition (MPT) between ~ 1.2 Ma to ~500 ka (also termed as ‘900 ka event’) marks a change in climatic periodicity, from 41 ka cycles to 100 ka cycles of increased intensity. In non-glaciated areas of Europe this climatic shift has been associated with pronounced acceleration of river incision, in part driven by increased sediment loads from periglacial hillslope processes. Until the Pleistocene, low-relief landscapes are thought to have dominated throughout Europe. Utilizing novel in-situ cosmogenic Krypton in zircon methodology (Dunai et al. 2022), we find direct evidence that this was indeed the case, and that these landscapes were profoundly transformed during the MPT.Our study area (Vogtland, Saxony, Germany) was never glaciated but was within 50 km of the ice margins during the largest Quaternary glaciations. For our study, we utilize a unique source of megacryst zircons (Ebersbrunn diatreme), whose exhumation, dispersal and burial history is recorded by cosmogenic Krypton. The megacryst zircons are found in the fluvial sediments of the current catchments downstream of the source (Raumbach, Göltzsch, Weiße Elster), however, also in a distal catchment (Weida), now disconnected from the source due to late Pleistocene superimposed drainage (Weiße Elster valley).The cosmogenic Krypton data from the megacryst zircons is commensurate with a long (1 to 3 Myr) exposure at or near the surface, or exhumation at a very low rate (<0.1 mMyr-1), followed by a period of burial of 600 to 900 kyr and a recent re-emergence in the active fluvial system. Samples collected further from the source (≥15 vs. 5 km) have longer burial histories. The extremely low erosion rates inferred prior to burial (<0.1 mMyr-1) are unprecedented for temperate regions in Europe, and late Quaternary erosion rates of landscapes with similarly moderate relief are two orders of magnitude faster. In situ cosmogenic 10Be and 26Al results on vein-quartz from the region address the latter findings.Based on our data and external constraints on climate and landscape evolution in Europe, the most likely scenario is that of a formerly stable, low-relief Plio-Pleistocene landscape whose transformation in response to periglacial processes commenced during marine isotope stage (MIS) 22 and was largely concluded by MIS 16. Incision of drainage that developed during and after the MPT formed the current moderate relief landscape.Dunai et al. (2022) Geochronology, https://doi.org/10.5194/gchron-4-65-2022
Low Power, Rugged Edge Computing provides a low cost, powerful solution for on the ground remote sensing in extreme environments
Authors: Frearson Nicholas , Plank Terry , Lev Einat , Dong LingLing , Bacon Conor
Published: February 2023

Ground based remote sensing devices increasingly incorporate low cost single board computers such as a Raspberry Pi to capture and analyze images and data from the environment. Useful and cheap as these devices are, they are not designed for use in extreme conditions and as a consequence often suffer from early failure. Here we describe a system that incorporates a commercially available rugged Edge Computer running embedded Linux that is designed to operate in remote and extreme environments. The AVERT system  (Anticipating Volcanic Eruptions in  Real Time) developed at Columbia University in New York and funded by the Moore Foundation uses solar and wind powered Sensor nodes configured in a spoke and hub architecture currently operating on two volcanoes overseen by the Alaska Volcano Observatory in the Aleutian Islands, Alaska. Multiple Nodes distributed around the volcanoes are each controlled by an Edge Computer which manages and monitors local sensors, processes and parses their data via radio link to a central Hub and schedules system components to wake and sleep to conserve power. The Hub Edge Computer collects and assembles data from multiple Nodes and passes it via satellite, cellular modem or radio links to servers located elsewhere in the world or cloud for near real-time analysis. The local computer enables us to minimize local power demand to just a few watts in part due to the extremely low power sleep modes that are incorporated into these devices. For instance, a Node incorporating a webcam, IRCam, weather station, Edge Computer, network switch, communications radio and power management relays draws only 4.5W on average. In addition, this level of local computing power and a mature Linux operating environment enables us to run AI algorithms at source that process image and other data to flag precursory indicators of an impending eruption. This also helps to reduce data volume passed across the network at times of low network connectivity. We can also remotely interrogate any part of the system and implement new data schemes to best monitor and react to ongoing events. Future work on the AI algorithm development will incorporate local multisensor data analytics to enhance our anticipatory capability.
Air-water gas transfer coefficient for shallow water
Authors: Repina Irina
Published: February 2023

Fluxes of GH gases across the water surface constitute an important part of the global climate. Because of the combination of small concentrations and  small fluxes, the determination of air–water gas fluxes presents unusual measurement difficulties. Direct measurements (i.e., eddy correlation) of the fluxes are rarely attempted.  Used in gas transport parameterization models were mainly developed for the open ocean. The differences, especially those between shallow sheltered systems and the open waters best fit by some published relationships, are ecologically important and do not appear yet to be measurable by other methods.The report discusses the determination of the transfer coefficient from direct measurements of methane and carbon dioxide fluxes in the case of shallow water bodies. Coastal zones, an estuary, a small lake and a river of differing bathymetry and local terrain are considered. The influence of footprint, surface condition, and atmospheric stability is investigated. In the case of a river, the current may also have an influence. It is shown that the inhomogeneous relief significantly affects the results of the convergence of measurements and model calculations. Determined that the model overestimates the fluxes in low winds. For CH₄, most of the transport appears to be by ebullition rather than diffusion and model would have underestimated the exchange by two orders of magnitude. New dependencies are proposed for determining the gas transfer coefficient for methane and carbon dioxide under conditions of shallow water and inhomogeneous relief. The work was supported by the Russian Science Foundation grant 22-47-04408.
Europa Clipper Mission Update
Authors: Korth Haje , Pappalardo Robert , Buratti Bonnie , Craft Kate , Howell Sam , Klima Rachel , Leonard Erin , Matiella Novak Alexandra
Published: February 2023

With a launch readiness date of late 2024, NASA’s Europa Clipper will set out on a journey to explore the habitability of Jupiter’s moon Europa. At the beginning of the next decade, the spacecraft will orbit Jupiter, flying by Europa more than 40 times over a four-year period to observe this moon’s ice shell and ocean, study its composition, investigate its geology, and search for and characterize any current activity. The mission’s science objectives will be accomplished using a highly capable suite of remote-sensing and in-situ instruments. The remote sensing payload consists of the Europa Ultraviolet Spectrograph (Europa-UVS), the Europa Imaging System (EIS), the Mapping Imaging Spectrometer for Europa (MISE), the Europa Thermal Imaging System (E-THEMIS), and the Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON). The in-situ instruments comprise the Europa Clipper Magnetometer (ECM), the Plasma Instrument for Magnetic Sounding (PIMS), the SUrface Dust Analyzer (SUDA), and the MAss Spectrometer for Planetary Exploration (MASPEX). Gravity and radio science will be achieved using the spacecraft's telecommunication system, and valuable scientific data will be acquired by the spacecraft’s radiation monitoring system. The project, flight system, and payload have completed their Critical Design Reviews, and the project has completed its System Integration Review, so that Europa Clipper is now formally in mission Phase D. The spacecraft and payload are currently under construction, as assembly, testing, and launch operations (ATLO) are well underway. Recent major milestones include the delivery to ATLO of the Propulsion Module and six instruments (E-THEMIS, Europa-UVS, EIS-WAC, PIMS, MASPEX, SUDA) and the assembly of the solar array wings. The integration of these instruments’ sensors on the spacecraft and its nadir-viewing deck and of the instrument electronics in vault has begun. The remaining instruments (ECM, EIS-NAC, MISE, REASON) are in mature stages of assembly and will be delivered in the next months. The science team is in the process of evaluating minor changes to the candidate tour, and is preparing a set of manuscripts describing the mission’s science and instruments for publication in the journal Space Science Reviews.
Dispersion modeling of the volcanic sulfur dioxide plumes from the simultaneous eruptive activity of Stromboli and Mt Etna on 28 August 2019
Authors: Castorina Giuseppe , Semprebello Agostino , Gattuso Alessandro , Italiano Francesco , Salerno Giuseppe , Sellitto Pasquale , Rizza Umberto
Published: February 2023

During the summer of 2019, both Mt. Etna and Stromboli volcanoes in Sicily were in the stage of no ordinary activity. Mt. Etna was featured by mild strombolian activity from the summit South East Crater producing a moderate SO2–ash rich plume 4 km above sea level (asl). Meanwhile, at 120 km far from Etna, on 3 July and 28August, the ordinary and typical mild explosive eruptive activity of Stromboli was interrupted by two paroxysms. Both events were characterized by pyroclastic flows and consistent emission of ash–SO2 rich plume, which spread up to height of 5–6 km asl.In this work, we explored the spatial dispersion of the volcanic plumes released by both Mt. Etna and Stromboli on August 28 by employing the Weather Research and Forecasting Chemistry (WRF–Chem) model. The simulation was specifically configured and run by considering the time-variable Eruptive Source Parameters (ESPs) related to the SO2 flux data for Stromboli and Mount Etna observed from ground by the FLAME DOAS scanning spectrometers network.In order to assess the predictive performance of the WRF–Chem model, the simulated SO2 dispersion maps were compared with data retrieved on 28 August from TROPOMI and OMI sensors onboard Sentinel–5p and Aura satellites. The results show a good agreement between WRF–Chem and satellite data. In fact, the simulated total mass of the emitted SO2 from the two volcanoes has the same order of magnitude as the satellite data. However, for the case of Stromboli, the total SO2 mass predicted by the WRF–Chem simulation is underestimated; this is likely due to inhibition of the real syn-eruptive SO2 detection by FLAME due to the extreme ash–rich volcanic plume released during the paroxysm.In conclusion, the results of these two test–cases demonstrate the feasibility of WRF–Chem model with a time-variable ESPs in reproducing different levels of volcanic SO2 and their dispersion into the atmosphere. For these reasons, our approach could represent an effective support for the assessment of local–to-regional air quality and flight security and, in case of particularly intense events, also on a global scale.