bluuebunny/crossref_metadata_2025 huggingface dataset:
Merging tTEM data and borehole lithological information to generate hydrogeologic structural models and redox conditions through Direct Sampling
Authors: Claes Niels , Frederiksen Rasmus Rumph , Vilhelmsen Troels Norvin , Foged Nikolaj , Kim Hyojin , Christiansen Anders Vest
Published: March 2021

Detailed 3D structural information of the subsurface is fundamental for the development of both hydrological and geochemical models. This structural information is often derived from geophysical mapping results. Some parts of a catchments areas are however inaccessible for the geophysical mapping or might suffer from low data quality, which results in information gaps. Multipoint statistics can be used to remediate these data gaps and incorporate uncertainty in the construction of the hydrogeological models. This results in an ensemble of plausible 3D hydrogeological models.

This project focusses on nitrate retention mapping. The approach taken is to start from the resistivity models that are obtained from the tTEM measurement campaign. These resistivity datasets are combined with borehole lithological data from the Danish national well-database in an automated procedure that estimates resistivity-to sand/clay translator functions. This results in a clay fraction – resistivity data pair for every point in the subsurface where resistivity data is collected. These clay fraction – resistivity data pairs are converted to discrete hydrogeological units through clustering. This procedure is performed because the groundwater model that uses the end-product of this workflow, uses hydrogeological units rather than resistivity values or clay fractions to define zones of similar hydrogeological behavior.

Direct sampling is used to go from the cluster information obtained at the resistivity model location to fill out the full model volume and generate multiple plausible model realizations. This method allows, at the same time, for incorporating uncertainty through separation of data into a hard  data set for the cluster information with higher probability, and a soft data set for the cluster information with lower probability. Since the redox conditions in the subsurface are related to the hydrogeological conditions, we are using this method to co-simulate hydrogeological units and redox conditions by merging the cluster training dataset with a redox condition training dataset that is constructed based on the cluster dataset and hydrogeochemical samples that are collected across the catchment. We combine the three training images: resistivity, cluster and redox condition, to simultaneous simulate the three variables in each grid point as a vector, instead of simulating them as separate variables.  The resulting set of  3D hydrogeologic structural models and redox condition models retains the complex geostatistical spatial relationships that can exists between the different type of datasets within the training image, making them suitable for nitrate retention modeling at catchment scale.
Kinematics of Cenozoic shortening across the foothills of the Western Kunlun Range (Xinjiang, China): the case of the Hotan anticline
Authors: Baby Guillaume , Simoes Martine , Barrier Laurie , Guilbaud Christelle , Van der Woerd Jérôme , Li Haibing
Published: March 2021

Quantitative constraints on the Cenozoic deformation of the northwestern edge of the Tibetan Plateau remain limited, in particular in terms of shortening rates and of their possible evolution over time. This is indeed the case for the Western Kunlun Range, along the southwestern rim of the Tarim Basin, even though surface geological data and an extensive database of seismic profiles allow to explore the sedimentary record of Cenozoic deformation. Here, we take advantage of these data to document the structural geometry and Cenozoic kinematics of the large scale east-west striking Hotan anticline along the mountain front. Four balanced cross-sections are constructed, and the temporal evolution of deformation is deciphered from the exceptionally seismically well imaged growth strata on the forelimb of the anticline.

The fold results from a broad unfaulted basement ramp anticline, subsequently deformed by a duplex structure that developed in the footwall units. The total shortening of the Hotan thrust system is relatively constant along strike, from ~40 to ~32 km. The shortening accommodated by the duplex varies laterally from west to east, from ~50-40 % to 0 % of the total shortening. 

Two distinct successive patterns of growth strata are recognised in the forelimb, and are interpreted to be representative of deformation on the basement ramp, followed by deformation related to the growth of the underlying duplex. Deformation on the basement ramp initiated by ~17 Ma, when calibrating growth seismic reflectors on surface magnetostratigraphic sections. Deformation of the underlying duplex began at ~12 Ma to the west and subsequently propagated eastward.

From these results on shortening and timing of deformation, we determine a shortening rate of 4-3 mm/yr from ~17 to ~7 Ma across the Hotan anticline. We find a significant subsequent decrease in shortening rates, possibly down to <0.5 mm/yr since the uppermost Miocene. These rates are compared to existing values and their regional significance is discussed.
Modelling the Soufrière Hills Volcano; Investigating the Montserrat magmatic system with co-analysis of EDM and GPS data
Authors: Johnson Alexander , Hickey James , Pascal Karen , Williamson Ben , Syers Racquel
Published: March 2021

Ground deformation offers vital insight into the activity of volcanoes, as well as the characteristics of the magmatic systems that feed them. The extended eruption of the Soufrière Hills Volcano (SHV) has allowed for the development of a comprehensive multi-disciplinary monitoring network, which has aided extensive research into the magmatic system underlying the volcano. The modern network comprises GPS, strainmeters, and cheaper Electronic Distance Measurement (EDM). However, the island’s EDM network has to date only being used for monitoring the SHV. Here, for the first time, we co-analyse the EDM dataset from 2010-19 with the GPS data from the same period. This study aims to delineate the modern magmatic system conditions by building 3D Finite Element Models, as well as assessing the best use of EDM data in modelling the SHV.

The island-wide deformation recorded over the past decade at the GPS network is broadly radial relative to the SHV dome, with a decreasing deformation rate. The EDM data shows line lengthening on the west and east flanks of the volcano, but minor line length shortening on the northern flank. We utilise Finite Element Modelling to model the SHV magmatic system as a single elongated prolate with 3D topography incorporated. We systematically test a wide range of parameters to explore how both EDM and GPS record perturbations to the magmatic system. Our preliminary results show that variations of certain parameters to the deeper magmatic system have an impact on both EDM and GPS timeseries, while some parameters (e.g., source pressure, source depth, and source location) have a more significant effect on EDM measurements than others (e.g., source shape).
Integrated analysis of plant gene expression and bacterial and protozoan community composition reveals changes related to root zonation, root cap and root hair formation
Authors: Ganther Minh , Rüger Lioba , Bonkowski Michael , Heintz-Buschart Anna , Tarkka Mika
Published: March 2021

This study was conducted within the framework of the DFG project SPP2089 “Rhizosphere Spatiotemporal Organization – a Key to Rhizosphere Functions” (project number 403641192).

As plant roots grow into the soil, the formation of biological gradients occurs at different spatial scales. It has been shown that plants recruit specific subsets of the soil bacterial community at their roots through excretion of mucilage at root tips and exudates at the sites of root hair formation. The promotion of or defense against certain bacterial taxa is also reflected in the composition of the protist communities that feed on bacteria.

Using high-throughput sequencing methods, we investigated emerging patterns in root gene expression in relation to bacterial and protozoan community structures. We found highly distinct root region specific patterns relating to differential root gene expression relating to growth, defense and transporter activity, as well as bacterial and protist (cercozoan) diversity. Root cap removal led to differently composed microbial communities, as well as a regulation of root genes relating to stress and defense. The lack of root hairs was only reflected in the amount of microbial carbon in soil and a small number of differentially expressed genes involved in cell wall processes.

We could show that the rhizosphere microbiome, is as dynamic as its environment. Root regions differentially affect microbial communities, which is also reflected in the expression of plant genes of categories relating to defense, immunity and stress. Our findings will further enhance our understanding of microbial root interactions at single root scale.
Long-term correlations in solar proxies and solar wind parameters
Authors: Giovannelli Luca , Reda Raffaele , Alberti Tommaso , Berrilli Francesco , Cantoresi Matteo , Del Moro Dario , Giobbi Piermarco , Penza Valentina
Published: March 2021

The long-term behaviour of the Solar wind and its impact on the Earth are of paramount importance to understand the framework of the strong transient perturbations (CMEs, SIRs). Solar variability related to its magnetic activity can be quantified by using synthetic indices (e.g. sunspots number) or physical ones (e.g. chromospheric proxies). In order to connect the long-term solar activity variations to solar wind properties, we use Ca II K index and solar wind OMNI data in the time interval between 1965 and 2019, which almost entirely cover the last 5 solar cycles. A time lag in the correlation between the parameters is found. This time shift seems to show a temporal evolution over the different solar cycles.

 
Global NWP Modeling of urban environments at ~1km resolution
Authors: McNorton Joe , Bousserez Nicolas , Arduini Gabriele , Agusti-Panareda Anna , Balsamo Gianpaolo , Boussetta Souhail , Choulga Margarita , Hadade Ioan , Hogan Robin
Published: March 2021

Urban areas make up only a small fraction of the Earth’s surface; however, they are home to over 50% of the global population. Accurate numerical weather prediction (NWP) forecasts in these areas offer clear societal benefits; however, land-atmosphere interactions are significantly different between urban and non-urban environments. Forecasting urban weather requires higher model resolution than the size of the urban domain, which is often achievable by regional but not global NWP models. Here we present the preliminary implementation of an urban scheme within the land surface component of the global Integrated Forecasting System (IFS), at recently developed ~1km horizontal resolution. We evaluate the representation error of fluxes and NWP variables at coarser resolutions (~9 km and ~31 km), using the high resolution as truth. We evaluate the feasibility of the scheme and its urban representation at ~1km scales. Availability of urban mapping data limit the affordable complexity of the global scheme; however, using generalisations model performance is improved over urban sites, even adopting simple schemes, and the modelled Urban Heat Island effects show broad agreement with observations. Several directions for future work are explored including a more complex urban representation, restructuring of the urban tiling and the introduction of an urban emissions model for trace gas emissions.
Prediction capabilities of GeoFlood for the delineation of flood-prone areas: the Tiber River case study
Authors: D'Angelo Claudia , Passalacqua Paola , Fiori Aldo , Volpi Elena
Published: March 2021

Land use and delineation of flood-prone areas require valuable and effective tools, such as flood mapping. Local authorities, in order to prevent and mitigate the effects of flood events, need simplified methodologies for the definition of preliminary flooded areas at a large scale. In this work, we focus on the workflow GeoFlood, which can rapidly convert real-time and forecasted river flow conditions into flooding maps. It is built upon two methodologies, GeoNet and the HAND model, making use only of high-resolution DTMs to define the geomorphological and hydraulic information necessary for flood inundation mapping, thus allowing for large-scale simulations at a reasonable economical and computational cost. GeoFlood potential is tested over the mid-lower portion of the river Tiber (Italy), investigating the conditions under which it is able to reproduce successful inundation extent, considering a 200-year return period scenario. Results are compared to authority maps obtained through standard detailed hydrodynamic approaches. In order to analyze the influence of the main parameters involved, such as DTM resolution, channel segmentation length, and roughness coefficient, a sensitivity analysis is performed. GeoFlood proved to produce efficient and robust results, obtaining a slight over-estimation comparable to that provided by standard costly methods. It is a valid and relatively inexpensive framework for inundation mapping over large scales, considering all the uncertainties involved in any mapping procedure. Also, it can be useful for a preliminary delineation of regions where the investigation based on detailed hydrodynamic models is required.
Jupiter's X-ray aurora during a mass injection and Io mass loading events observed by XMM-Newton, Hubble, and Hisaki
Authors: Wibisono Affelia , Branduardi-Raymont Graziella , Dunn Will , Kimura Tomoki , Coates Andrew , Grodent Denis , Yao Zhonghua , Kita Hajime , Rodriguez Pedro , Gladstone Randy , Bonfond Bertrand , Haythornthwaite Richard
Published: March 2021

Voyager 1 detected the first extra-terrestrial UV auroral emissions when it explored the Jupiter system in 1979 while the planet’s X-ray aurora was discovered later that year by the Einstein Observatory. Electrons are accelerated into Jupiter’s atmosphere near the poles and excite native molecular and atomic hydrogen. These then release UV photons after returning to the ground state. The same population of precipitating electrons can also emit high energy (>2 keV) X-ray photons by bremsstrahlung to produce Jupiter’s hard X-ray aurora. At higher latitudes and within the oval of UV and hard X-ray emissions is where the more diffuse UV and low energy (<2 keV) soft X-ray aurorae are found.  Charge exchange processes between precipitating ions and neutrals in the gas giant planet’s atmosphere are responsible for the soft X-ray emissions.

Simultaneous observations of Jupiter’s UV and X-ray aurorae were carried out by the Hubble Space Telescope (HST), Hisaki satellite and XMM-Newton in September 2019 to support Juno’s 22nd perijove. Images of the northern far UV aurora by HST showed internally driven dawn storms and injection events occurring at least twice during the observation period. These features are thought to be caused by magnetic reconnection happening in the middle magnetosphere. This subsequently leads to the dipolarization of the field lines which injects hot magnetospheric plasma from the middle to the inner magnetosphere. Hisaki saw an impulsive brightening in the Io plasma torus on the day of the second event showing that there was indeed a large-scale injection that penetrated the central torus in the inner magnetosphere. At this time, the northern aurora brightened in both extreme UV and hard X-ray, which suggests that there was an increase in electron precipitation.  There was no response from the soft X-ray aurora, and no quasi-periodic pulsations, often observed in the auroral emissions, were detected during either of the events. X-ray spectral analysis reveals that the precipitating ions were iogenic. We conclude that we have witnessed two cases of mass injection in the Jovian inner magnetosphere due to Io mass loading events.
Coexistence of equatorial waves & turbulence in moist shallow water simulations 
Authors: Schröttle Josef , Suhas Dl , Harnik Nili , Sukhatme Jai
Published: March 2021

Moist equatorial waves, responsible for a large fraction of synoptic and intraseasonal tropical variability, are visible in satellite observations of cloud top temperature and outgoing longwave radiation, with familiar dispersion relations appearing in space time spectra once a background red-like spectrum is removed (Kiladis et al., 2009).

Studies have suggested that the large-scale planetary waves in the equatorial region can be excited by smaller scale gravity waves (Yang & Ingersoll, 2013), baroclinic waves from the extratropics (Wedi & Smolarkiewicz, 2010), or localized synoptic scale heating (Gill 1980, 1982). In this study we examine the possibility that a continuous forcing of anomalies at the mesoscale can, through a turbulent upscale cascade, excites these waves, thus explaining both: the peaks along dispersion relations and the background red spectrum.

Our underlying assumption is that within the tropics (excluding wave forcing from the extratropics), a prerequisite to form coherent heating of ≈1000 km zonal length on an aqua planet is self-aggregation. Over the last two decades, self-aggregation has been studied over a wide range of scenarios up to the atmospheric mesoscale. In this study we examine the aggregation from the mesoscale up to the planetary scale, by applying mesoscale stochastic forcing in idealized spherical shallow water model. In particular, we examine the dependence of the large scale spectra on the field being stochastically forced, and on the existence of moisture.

We find that indeed, continuous stochastic forcing at the mesoscale can excite two-dimensional turbulence and linear tropical wave modes. When vorticity or moisture are forced in the simulations at wavenumber 100, a classical -5/3 slope of the eddy kinetic energy spectrum forms in an upscale energy cascade up to the planetary scale. Furthermore, equatorial waves emerge and Wheeler-Kiladis plots reveal a rich temporal and spatial structure of Rossby, Kelvin, Yanai, and Inertial Gravity waves. On the other hand, stochastic forcing of the divergence, or height fields only leads to a turbulent field when applied at planetary scales. Some explanations for this strong dependence on the type of forcing, and the role of moisture, will be discussed. 
Enhancement of seasonal hydrological forecasting with “pattern-based” large-scale climatology 
Authors: Yang Wei , Foster Kean , Pechlivanidis Ilias G.
Published: March 2021

The hydrological forecasting on seasonal (up to 7 months ahead) timescales is needed for decision-making in the hydropower sector. Being one of the vital influencing factors on hydro-production, a lot of development in dynamical forecasting at seasonal timescales has been done recently. However, the forecast bias still remains in different variables and consequently the skill of corresponding streamflow forecasts varies from month to month.

This study aims to explore the potential for “pattern-based” seasonal hydrological forecasts that make use of hydrological weather regimes and teleconnection indices to improve forecast skill. The work is built on the hypothesis that hydrological weather regimes and teleconnection indices can be used to select analogue years (setting an ensemble) from a record of historical precipitation and temperature data with which to force a hydrological model to generate tailored seasonal forecasts of reservoir inflows. The hydrological weather regimes have been classified based on the concept of fuzzy sets using the anomalies of daily mean sea level pressure from reanalysis data (i.e., ERA-Interim). Precipitation records, measured in the Umeälven river basin during 1981-2016 are used as local observations to optimize each fuzzy rule that describes a type of “average” variability of local climate in terms of the frequency and magnitude of precipitation events. The teleconnection indices are compiled from the Climate Prediction Center, which describe global atmospheric variability. The methodology has been applied to 84 sub-catchments across seven of the most important hydropower producing river systems in Northern Sweden. However, the performance for the Umeälven river system is of particular interest here.

Comparing to the traditional Ensemble Streamflow Prediction (ESP) method, the “pattern-based” seasonal hydrological forecasting shows a marked improvement, which is likely due to the weighted analogue-ESP approach as well as the selected analogues using the large-scale climate information described by hydrological weather regimes and teleconnection indices. The general performance of the two different approaches for selecting the analogues are similar; however, occasionally there are large differences in both the best analysis lead times and the spread of skill across the sub-catchments suggesting that those results are achieved using analogues based on different physical processes.
Visualisation in climate services: status and recommendations
Authors: Terrado Marta , Urquiza Diana , Octenjak Sara , Nicodemou Andria , Bojovic Dragana , Calvo Luz , Christel Isadora
Published: March 2021

The visual communication of climate information is one of the cornerstones of climate services. Characteristics that make a climate service self-explanatory rely on the visual modes it employs, e.g. maps, graphs or infographics, and the visual channels applied for the translation of multidimensional data, e.g. combination of colours, shapes or slopes. 

Climate scientists have traditionally used predetermined types of visualisations to present climate data, including flood maps, heat maps or choropleth maps. However, such a tradition neglects a plethora of stakeholders (e.g. businesses, policy makers, citizens) that are increasingly involved in climate adaptation and that are less familiar with the traditional ways of presenting these data. In this sense, there is a need to advance towards climate services visualisations that can guide climate change adaptation decisions by helping users to interpret and use the information as simply and quickly as possible.

Effective visualisations should achieve a balance between the amount of represented data, its robustness (i.e. the representation of scientific confidence and consensus) and saliency (i.e. the relevance of the information to user needs). Therefore, choices regarding the representation of probabilities (e.g. using terciles or information on extreme events), the representation of uncertainty (e.g. showing the ensemble range or filtering by a skill threshold), the type of visual encoding (e.g. selection of the colour palette, use of shapes and sizes) as well as the terminology and language used, are some aspects that can significantly impact the way users interpret climate data.

We describe the main challenges for the visualisation of climate services identified during a visualisation workshop with representatives from 22 climate services projects involved in the Climateurope network, an EU-funded coordination and support action. In break-out group discussions, participants shared their experiences in the development of effective climate services visualisations and the lessons learned. Findings show that the chosen representation of uncertainty and probabilities tends to be case specific and that there is a preference for interactive visualisations where information is gradually disclosed. Minimising the use of technical concepts in visualisations was highlighted as an objective that requires further attention. The analysis of the obtained results provides a picture of the current status of the climate services visualisation field in Europe and gives recommendations for the development of the next generation of climate services.
Drag-Based Ensemble Model (DBEM) to predict the heliospheric propagation of CMEs
Authors: Calogovic Jasa , Dumbović Mateja , Sudar Davor , Vršnak Bojan , Martinić Karmen , Temmer Manuela , Veronig Astrid
Published: March 2021

The Drag-based Model (DBM) is an analytical model for heliospheric propagation of Coronal Mass Ejections (CMEs) that predicts the CME arrival time and speed at Earth or any other given target in the solar system. It is based on the equation of motion and depends on initial CME parameters, background solar wind speed, w and the drag parameter γ. A very short computational time of DBM (< 0.01s) allowed us to develop the Drag-Based Ensemble Model (DBEM) that considers the variability of model input parameters by making an ensemble of n different input parameters to calculate the distribution and significance of the DBM results. Using such an approach, we apply DBEM to determine the most likely CME arrival times and speeds, quantify the prediction uncertainties and calculate the confidence intervals. Recently, a new DBEMv3 version was developed including the various improvements and Graduated Cylindrical Shell (GCS) option for the CME geometry input as well as the CME propagation visualizations. Thus, we compare the DBEMv3 with previous DBEM versions (e.g. DBEMv2), evaluate it and determine the DBEMv3 performance and errors by using various CME-ICME lists. Compared to the previous versions, the DBEMv3 provides very similar results for all calculated output parameters with slight improvement in the performance. Based on the evaluation performed for 146 CME-ICME pairs, the DBEMv3 performance with mean error (ME) of -11.3 h, mean absolute error (MAE) of 17.3 h was obtained, similar to previous DBM and DBEM evaluations. Fully operational DBEMv3 web application was integrated as one of the ESA Space Situational Awareness portal services (https://swe.ssa.esa.int/current-space-weather) providing an important tool for space weather forecasters.
Creating a more fluent conversation between data, model and users through interactive Jupyter Notebooks
Authors: Peñuela Andres , Pianosi Francesca
Published: March 2021

Reproducibility and re-usability of research requires giving access to data and numerical code but, equally importantly, helping others to understand how inputs, models and outputs are linked together. Jupyter Notebooks is a programming environment that dramatically facilitates this task, by enabling to create stronger and more transparent links between data, model and results. Within a single document where all data, code, comments and results are brought together, Jupyter Notebooks provide an interactive computing environment in which users can read, run or modify the code, and visualise the resulting outputs. In this presentation, we will explain the philosophy that we have applied for the development of interactive Jupyter Notebooks for two Python toolboxes, iRONS (a package of functions for reservoir modelling and optimisation) and SAFE (a package of functions for global sensitivity analysis). The purposes of the Jupyter Notebooks are two: some Notebooks target current users by demonstrating the key functionalities of the toolbox (‘how’ to use it), effectively replacing the technical documentation of the software; other Notebooks target potential users by demonstrating the general value of the methodologies implemented in the toolbox (‘why’ use it). In all cases, the Notebooks integrate the following features: 1) the code is written in a math-like style to make it readable to a wide variety of users, 2) they integrate interactive results visualization to facilitate the conversation between the data, the model and the user, even when the user does not have the time or expertise to read the code, 3) they can be run on the cloud by using online computational environments, such as Binder, so that they are accessible by a web browser without requiring the installation of Python. We will discuss the feedback received from users and our preliminary results of measuring the effectiveness of the Notebooks in transferring knowledge of the different modelling tasks.
Characteristics of dynamic crack propagation in a weak snowpack layer over its entire life cycle
Authors: Bergfeld Bastian , van Herwijnen Alec , Bobillier Gregoire , Schweizer Jürg
Published: March 2021

For a slab avalanche to release, a weak layer buried below a cohesive snow slab is required, and the system of weak layer and slab must support crack propagation over large distances. This process, called “dynamic crack propagation”, is highly relevant for avalanche release, and computational models are nowadays able to model crack propagation over increasingly larger scales. Field measurements on dynamic crack propagation are however very scarce, although these are required to validate models. We therefore performed a series of flat field PST experiments up to ten meters long over a period of 10 weeks. During this time, PST results evolved from crack arrest to full propagation and back to crack arrest – reflecting the life cycle of the weak layer. All PST experiments were analyzed using digital image correlation to derive high-resolution displacement fields to compute dynamic crack propagation metrics, including crack length and speed as well as touchdown distance, the distance from the crack tip to the trailing point where the slab comes into contact with the substratum. Comparing the displacement fields during sawing to a mechanical model, we estimated the effective elastic modulus of slab and weak layer as well as the specific fracture energy of the weak layer. Our results show how dynamic crack propagation characteristics change over the life cycle of a weak layer and how these measures relate to snowpack properties such as load and effective elastic modulus of the slab. We found that crack speed was highest for PSTs resulting in full propagation and that the touchdown length increased with increasing elastic modulus of the slab. Our dataset provides unique insight into the dynamics of crack propagation, and provides valuable data to validate models used to study sustained crack propagation.
Cyclone-Anticyclone asymmetry of eddy detection on gridded altimetry product in the Mediterranean Sea 
Authors: Stegner Alexandre , Le Vu Briac , Dumas Franck , Ghannami Mohamed , Nicolle Amandine , Faugere Yannice
Published: March 2021

Thanks to a Observing System Simulation Experiment (OSSE) that simulate the along-track satellite measuring process on the sea surface of the high resolution model CROCO-MED60v40-15-16 we investigate how the reliability and the accuracy of the detected eddies are influenced by the satellite sampling and the mapping procedure. The main result of this study is that there is that there is a strong cyclone-anticyclone asymmetry of the eddy detection on the altimetry products AVISO/CMEMS in the Mediterranean Sea. Large scale cyclones having a characteristic radius larger than the local deformation radius are much less reliable than large scale anticyclones. We estimate, that less than 60% of these cyclones detected on gridded altimetry product are reliable, while more than 85% of mesoscale anticyclones are reliable. Besides, both the barycenter and the size of these mesoscale anticyclones are relatively accurate. This asymmetry comes from the difference of stability between cyclones and anticyclones. Large mesoscale cyclones often splits into smaller sub mesoscale structures hav ing a rapid dynamical evolution. The high resolution model CROCO-MED60v40 shows that this complex dynamic is too fast and too small to be accurately captured by the gridded altimetry products based on a strong spatio-temporal  interpolation. The later smooth out this sub mesoscale dynamics and tend to generate an excessive number of unrealistic (i.e. unreliable) mesoscale cyclones in comparison with the reference field. On the other hand, large mesoscale anticyclones,  which are more robust and that evolve more slowly, can be spatially resolved and accurately tracked by standard altimetry products.  However, we confirm that gridded altimetry products have a systematic bias on the eddy intensity and especially for anticyclones. The azimuthal geostrophic velocities are always underestimated on the AVISO/CMEMS products even for large mesoscale anticyclones. 
Evaluation of a short-term ensemble water level forecasting system: case of the Chaudière River
Authors: Bessar Mohammed Amine , Anctil François , Matte Pascal
Published: March 2021

The quality of water level predictions is highly dependent on the success of the flow forecasts that inform the hydraulic model. Ensemble predictions, by considering several sources of uncertainty, provide more accurate and reliable forecasts. In this project, we aim to evaluate a water level ensemble prediction system coupling a hydraulic model to an ensemble streamflow prediction system accounting for 3 sources of uncertainty: meteorological data, hydrological processing (multimodel) and data assimilation to update the initial conditions. The hydraulic model is previously calibrated and validated and the roughness coefficients are adapted as a function of flow according to predefined relationships developed for several river segments. The forecasts reliability and accuracy are then assessed at each layer of the forecasting system and the outcomes are illustrated comparing the ensembles skills and reliability for the considered events. Overall, the results show that accounting of the hydrometeorological uncertainty improves the performances of the water level forecasts for different lead times.
Products and Services Available from U.S. NOAA NCEI Archive of Water Level Data
Authors: Sweeney Aaron , Mungov George , Wright Lindsey
Published: March 2021

The U.S. National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information (NCEI) archives analog and digital coastal water level data and ocean-bottom pressure data, digitizes select analog data, and performs quality-control and tidal analysis of these data.  The analog tide gauge records (marigrams) cover selected tsunami events between 1854 and 1981 observed at stations across the globe.  There are 3,486 high-resolution scanned marigrams in the archive.  The digital tide gauge data, primarily U.S. stations, have been collected at 1-minute sampling since 2008.  The ocean-bottom pressure data have been collected since 1983.  These time-series data are complementary to the maximum wave heights recorded in the NCEI/World Data Service Global Historical Tsunami Database.  With the introduction of visual timeline inventories, our NOAA partners have helped us identify, recover, and backfill gaps in our archive.  All water level data and products are converted to standardized file formats to reduce barriers to re-use. We provide quality-controlled water level data, computed astronomical tides, details on the harmonic tidal analysis results, and spectra to assess the quality of the de-tiding. Researchers use the quality-controlled data to validate tsunami propagation and storm surge models.  Select scanned marigram images are digitized into numerical time-series data by hand-selecting data points along the inked tidal curves. Though automated data point selection capabilities exist, when tested, they did not accurately detect faint traces and consistently failed to correctly select the peak and trough values. Hand-selection ensured that the maximum and minimum values important across water level research would be accurately recorded. From 2016 to 2019, we have digitized 48 of these images, across ten tsunami events, into ready-to-use, digital time-series data.  In the event of a tsunami, we augment our holdings by collecting and processing data from the National Hydrographic Services in the affected regions and from the United Nations Education, Scientific and Cultural Organization Intergovernmental Oceanographic Commission (UNESCO IOC) Sea Level Stations Monitoring Facility. Currently, UNESCO IOC does not process these data. These data products are then made available via Tsunami Event Pages. 
The Utility of the Standardized Evaporative Stress Ratio in Flash Drought Detection, Monitoring, and Evaluation
Authors: Christian Jordan , Hunt Eric , Basara Jeffrey , Otkin Jason
Published: March 2021

Flash drought is a critical subseasonal phenomenon that leads to significant environmental and socioeconomic impacts. Given the short timeframe in which these events development (a few weeks to a couple of months), detection and monitoring of rapid drought intensification remains a challenging task. As such, it is essential to have an environmental variable or a set of environmental variables that effectively evaluate flash drought development. This presentation provides an overview of the standardized evaporative stress ratio (SESR) and its utility in 1) detecting flash drought events, 2) monitoring the evolution of flash drought development, 3) quantifying the intensity (rate of intensification) of flash drought, and 4) representing impact (evaporative stress) on the environment. While the calculation of SESR is relatively simple (the ratio of evapotranspiration and potential evapotranspiration), approaches using evaporative stress can provide a wealth of information with respect to flash drought characteristics (e.g., timing, intensity (rate of change towards drought), severity (magnitude of evaporative stress), length, and shape/evolution). The diverse utility of SESR is presented with known flash drought case studies, such as the 2012 flash drought in the central United States and the 2010 flash drought in western Russia. Additional applications of SESR are also discussed, including climatological analysis and real-time flash drought monitoring.
Cenozoic reconstruction of Cape Darnley Bottom Water paleo-distribution imprinted in the drift formation history off MacRobertson Land Shelf, East Antarctica
Authors: Nielsen Ricarda , Uenzelmann-Neben Gabriele
Published: March 2021

Formation of Antarctic Bottom Water (AABW) plays an essential role within Meridional Overturning Circulation and is widely accepted to be the engine of global Thermohaline Circulation (THC), which is sensitive to climate changes. Studying paleo conditions and changes of AABW distribution during warm and cold periods is fundamental to gain knowledge about its interaction and response to climate changes, which helps to understand recent and future changes of THC due to global warming.

West of Prydz Bay, along MacRobertson Land Shelf area, a recent production of dense shelf water in the Cape Darnley Polynya and outflow as so-called Cape Darnley Bottom Water (CDBW) along the Wild Canyon has been recognized. CDBW contributes around 6-13% to the total circumpolar AABW. In order to understand the paleo conditions of AABW it is necessary to investigate the paleo-evolution of CDBW. To do this, we have studied the formation history of a 200 km long sediment drift (Darnley Drift herein) at the western flank of the Wild Canyon. We utilized more than 13.000 km of multi-channel seismic reflection data and lithological Data of ODP Site 1165.  

We characterized Darnley Drift to be a mixed turbiditic-contourite drift formed by an interplay of downslope and along-slope processes. During the Oligocene, turbiditic outflow dominated along the later formed Wild Canyon. An onset of CDBW can be inferred during the early Miocene, forming an asymmetric channel-levee system along the Wild Canyon. After the mid-Miocene Climatic Optimum a major climate change occurred, resulting in a strong intensification of bottom currents and major growth of the drift with simultaneous areas of non-deposition and erosion. This was followed by a sharp reduction of sedimentation rates. Since the late Miocene the growth of Darnley Drift is further dominated by contourite bottom currents.
A neural network-based mid-term prognosis of geomagnetic storms that uses pre-storm effects related to current sheets and magnetic islands
Authors: Fridman Mikhail
Published: March 2021

Mid-term prognoses of geomagnetic storms require an improvement since theу are known to have rather low accuracy which does not exceed 40% in solar minimum. We claim that the problem lies in the approach. Current mid-term forecasts are typically built using the same paradigm as short-term ones and suggest an analysis of the solar wind conditions typical for geomagnetic storms. According to this approach, there is a 20-60 minute delay between the arrival of a geoeffective flow/stream to L1 and the arrival of the signal from the spacecraft to Earth, which gives a necessary advance time for a short-term prognosis. For the mid-term forecast with an advance time from 3 hours to 3 days, this is not enough. Therefore, we have suggested finding precursors of geomagnetic storms observed in the solar wind. Such precursors are variations in the solar wind density and the interplanetary magnetic field in the ULF range associated with crossings of magnetic cavities in front of the arriving geoeffective high-speed streams and flows (Khabarova et al., 2015, 2016, 2018; Adhikari et al., 2019). Despite some preliminary studies have shown that this might be a perspective way to create a mid-term prognosis (Khabarova 2007; Khabarova & Yermolaev, 2007), the problem of automatization of the prognosis remained unsolved.
Rapid, paced metamorphism of blueschists from laser-based Lu-Hf garnet-domain geochronology and LA-ICMPS trace element mapping
Authors: Tual Lorraine , Smit Matthijs , Cutts Jamie , Kooijman Ellen , Kielman-Schmitt Melanie , Foulds Ian
Published: March 2021

Unravelling the timing and rate of subduction-zone metamorphism requires linking the composition of petrogenetic indicator minerals in blueschists and eclogites to time. Garnet is a key mineral in this regard, not in the least because it best records P-T conditions and changes therein and can be dated, using either Lu-Hf or Sm-Nd chronology. Bulk-grain garnet ages are the norm and can provide important and precise time constraints on reactions across both facies. Domain dating, i.e., dating of individual growth zones, moves beyond that. Domain dating by combining mechanical micro-milling and Sm-Nd chronology yielded important constraints on garnet-growth and fluid-release rates for blueschists (e.g., Dragovic et al., 2015). Developing this method for Lu-Hf chronology and, importantly, for "common-sized" garnet (≤1 cm) provides an important opportunity to further explore the potential of this approach.

We combined a low-loss micro-sampling technique in laser cutting with a refined Lu-Hf routine to precisely date multiple growth zones of a sub-cm-sized garnet in a blueschist. The targeted grain from a glaucophane-bearing micaschist from Syros Island, Greece, was chemically characterized by major- and trace-element mapping (EPMA, LA-ICPMS) and five zones were extracted using a laser mill. The three core and inner mantle zones are chemically comparable and identical in age within a 0.1 Myr precision (2σ). The outer two zones are chemically distinct and are resolvably younger (0.2-0.8 Myr). The timing of these two major garnet-growth episodes, together with the variations in trace-element chemistry, constrain important fluid-release reactions, such as chloritoid-breakdown. The data show that the integral history of garnet growth in subduction zones may be extremely short (<1 Myr), but may, even in that short timeframe, consist of multiple short pulses. Garnet-forming reactions clearly are localized and, thus, associated with focussed high-flux fluid flow. Beyond subduction-zone processes, our new protocol for zoned garnet Lu-Hf geochronology of "common-sized" garnet opens possibilities for constraining the causes and rates of garnet growth and in turn, the pace of tectonic processes in general.

 

Dragovic, B., Baxter, E.F. and Caddick, M.J., 2015. Pulsed dehydration and garnet growth during subduction revealed by zoned garnet geochronology and thermodynamic modeling, Sifnos, Greece. Earth and Planetary Science Letters, 413, pp.111-122.
Controls on streamwater age in a saturation overland flow-dominated catchment
Authors: Lapides Dana , Dralle David , Rempe Daniella , Dietrich William , Hahm W. Jesse
Published: March 2021

Water age and flow pathways should be related; however, it is still generally unclear how integrated catchment runoff generation mechanisms result in streamflow age distributions at the outlet. Here, we combine field observations of runoff generation at the Dry Creek catchment with StorAge Selection (SAS) age models to explore the relationship between streamwater age and runoff pathways. Dry Creek is an intensively monitored catchment in the northern California Coast Ranges with a Mediterranean climate and thin subsurface critical zone. Due to limited storage capacity, runoff response is rapid (~1-2 hours), and total annual streamflow consists predominantly of saturation overland flow, based on field mapping of saturated extents and runoff thresholds. Even though SAS modeling reveals that streamflow is younger at higher wetness states, flow is still typically older than one day and thus older than event water. Because streamflow is mostly overland flow, this means that a significant portion of overland flow must derive from groundwater returning to the surface, consistent with field observations of exfiltrating head gradients, return flow through macropores, and extensive saturation days after storm events. We conclude that even in a landscape with widespread overland flow, runoff pathways may be longer than anticipated, with implications for contaminant delivery and biogeochemical reactions. Our findings have implications for the assumptions built into classic hydrograph separation inferences, namely, that overland flow is not all new water.
Are marine heatwaves increasing the likelihood of terrestrial heatwaves? 
Authors: Pathmeswaran Charuni , Perkins-Kirkpatrick Sarah , Sen Gupta Alex , Hart Melissa
Published: March 2021

Despite numerous studies that have examined terrestrial or marine heatwaves independently, little work has been done investigating any possible association between the two. Examination of a limited number of past events suggests that co-occurring terrestrial and marine heatwaves may have common drivers, or may interact with each other. For example, a recent study1 identified common remote drivers behind the major marine heatwave that developed in the South Atlantic during the summer of 2013/14 and terrestrial heatwaves over South America. Co-occurring events could also potentially interact via local land-sea interactions, thereby altering the likelihood of these co-occurring events. This study will explore possible links between adjacent coastal marine and terrestrial heatwaves. We will investigate the likelihood of co-occurrence of terrestrial and marine heatwaves, using statistical analysis of observational temperature data. We will also investigate the mechanisms driving co-occurring events, including the local fluxes, synoptic conditions, and links to large scale modes of climate variability