bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploration of Distributed Acoustic Sensing (DAS) data-space using a trans-dimensional algorithm, for locating geothermal induced microseismicity
Authors: Piana Agostinetti Nicola , Bozzi Emanuele , Villa Alberto , Saccorotti Gilberto
Published: March 2022

Distributed Acoustic sensing (DAS) data have been widely recognised as the next generation of  seismic data for applied geophysics, given the ultra-high spatial resolution achieved. DAS data are recorded along a fiber optic cable at pre-defined distances (called “channels”, generally with 1-10 meters spacing). DAS data have been benchmarked to standard seismic data (e.g. geophones) for tasks related to both exploration and monitoring of georesources.

The analysis of DAS data has to face two key-issues: the amount of data available and their “directionality”. First, the huge amount of data recorded, e.g. in monitoring activities related to georesources exploitation, can not be easily handled with standard seismic workflow, given the spatial and temporal sampling (for example, manual picking of P-wave arrivals for 10 000 channels is not feasible). Moreover, standard seismic workflow have been generally developed for “sparse" network of sensors, i.e. for punctual measurements, without considering the possibility of recording the quasi-continuous seismic wavefield along a km-long cable. With the term “directionality" we mean the ability of the DAS data to record horizontal strain-rate only in the direction of the fiber optic cable. This can be seen as a measure of a single horizontal component in a standard seismometer. Obviously, standard seismic workflow have not been developed to work correctly for a network of seismometers with a unique horizontal component, oriented with variable azimuth from one seismometer to the other. More important, “directionality” can easily bias the recognition of the seismic phase arriving at the channel, which could be, based on the cable azimuth and the seismic noise level, a P-wave or an S-wave. 

We developed a novel application for exploring DAS data-space in a way that: (1) data are automatically down weighted with the distance from the event source; (2) recorded phases are associated to P- or S- waves with a probabilistic approach, without pre-defined phase identification; and (3) the presence of outliers is also statistically considered, each phase being potentially a converted/refracted wave to be discarded. Our methodology makes use of a trans-dimensional algorithm, for selecting relevant weights with distance. Thus, all inferences in the data-space are fully data-driven, without imposing additional constrains from the seismologist.
Using radar-derived precipitation data for hydrological modelling in selected study sides in Norway
Authors: Sienel Jessica , Schönfelder Lennart , Seidel Jochen
Published: March 2022

Gathering accurate precipitation data is an important task for setting up hydrological models. In Norway, the gauge network density is higher in the southern parts and decreases in the north. Furthermore, the amount of high evaluated precipitation gauges is rather scarce. Radar data is available but lacks an accurate reflectivity-precipitation relation and errors in precipitation estimation are caused for example by beam blockage.

For modelling purposes, this study aims to evaluate whether the application of radar derived data gives any benefit, especially when modelling in a higher temporal resolution. The results of this study can give decision support for modellers having difficulties choosing the precipitation product. For that cause, spatial interpolated precipitation products were evaluated and compared in terms of performance in hydrological models. The Meteorological Institute Norway publishes gridded hourly datasets covering the Norwegian mainland: seNorge2, where gauge data is interpolated using an optimal interpolation, and the numerical weather prediction product (NWP), a combination of gauge data, radar data and a numerical weather model. Five different catchments were simulated in the numerical precipitation-runoff model HYPE with both datasets for comparison. The catchments vary in area, hydrological regime and availability of nearby gauges. The simulation was done in an hourly time step in order to compare precipitation variability on a small time scale.

In this study, a calibration method was developed that generates comparable and stable performance results in terms of the Kling–Gupta efficiency (KGE) for each catchment and dataset. The resulting discharges and water balances of the catchments were analysed and compared. Additionally, selected precipitation events, where the precipitation products were not able to describe atmospheric processes appropriately, were analysed. The datasets were further compared by spatially accumulating annual precipitation sums over the catchments, by using a private weather station to evaluate the fit of the data and by comparing the runoff and precipitation volume of the basins.

Preliminary results show the significant differences in water volume and spatial distribution of precipitation between these products. Furthermore, when comparing a private gauge with the precipitation products at an ungauged area, daily precipitation data tends to be more accurate than hourly data.
A perspective on substorm dynamics from 10 years of Auroral Kilometric Radiation
Authors: Waters James , Jackman Caitriona , Whiter Daniel , Forsyth Colin , Fogg Alexandra , Lamy Laurent , Cecconi Baptiste , Bonnin Xavier , Issautier Karine
Published: March 2022

Auroral Kilometric Radiation (AKR) is terrestrial radio emission that originates from high latitude magnetic field lines. The intensity of AKR increases when the magnetosphere is perturbed, and so can indicate the presence of driving from the solar wind. This is true for structures that can vary in scale such as pressure pulses, as well as substorm onsets that follow periods of negative turnings in the Z component of the interplanetary magnetic field. In the latter case, AKR intensification correlates with the strengthening of high-latitude current systems in the ionosphere as the magnetotail current is reconfigured. As well as this, morphological changes in the AKR source region have also been observed to coincide with substorm onset, with an intensification of the AKR emission often accompanied by a low frequency extension, interpreted as an expansion of the source region to higher altitudes along the field line. Although the directivity and source region localisation of AKR make the observations highly dependent on observer local time and latitude, we isolate AKR from Wind radio observations made over a decade and examine the observations with respect to the spacecraft viewing position, accounting for such effects. Using lists of substorm onsets, we examine the AKR power and the spectral extent of the emission with respect to the substorm timeline, expanding on previous studies of the AKR response. Results show a clear increase in AKR power that precedes substorm onset by approximately 20 minutes, and confirm a proportionally higher intensification in lower frequency AKR sources. This in turn indicates quantitatively the spatial response of parallel electric fields after the loading of magnetic flux during substorm growth phase. In characterising the typical AKR response during substorms, these results can inform observations of magnetospheric changes during sudden commencement events and those that are seperate from substorm dynamics.
Litho- and cyclostratigraphy of the Aalenian Opalinusclay Formation in the Swabian Alb deduced from downhole logging data
Authors: Leu Katharina , Zeeden Christian , Wonik Thomas , Mann Thomas , Erbacher Jochen , Bornemann André
Published: March 2022

From 2019 to 2021, three cores were drilled at different locations in the southern German Swabian Alb as part of the SEPIA project (Sequence Stratigraphy of the Aalenian in Southern Germany). They comprise sediments of 200 to 250 m length and are penetrating Lower and Middle Jurassic strata from the Pliensbachian to Bathonian stages (~ 190-166 Ma). The aim of this project is the development of a sequence stratigraphic model of the South German Basin at the transition from the Lower to Middle Jurassic time. Conclusions should be drawn towards the source area of the sediments as well as on the influence of sea level fluctuations on sedimentation.

Today, the Swabian Alb is a SW-NE trending mountain chain consisting of mainly carbonate rocks, and is one of the most distinctive regions in Germany where Jurassic strata is cropping out. During the middle Jurassic, Europe was almost completely covered by a shallow epi-continental sea including several small emerging areas or islands, located at latitudes about 15° lower than today. Southern Germany experienced predominant deposition of fine clastic sediments in a tropical climate. The most common sediments of this period are dark clays and oolithic ironstones, whereas condensation and discontinuity surfaces occur in many instances. Accommodation space for these sediments was not only generated by changes in sea level, but also by continuing subsidence of the area, explaining the inhomogeneous thickness and changes in facies of the sediments.

The geophysical downhole logging data of the stratigraphic record is used to develop a lithological classification and correlation of the boreholes sediments by the application of a cluster analysis to the data. Furthermore, the downhole logging data is used to perform cyclostratigraphy in selected intervals. The focus of the intervals chosen for cyclostratigraphy lies on the Aalenian stage, as this stage holds the most continuous and extended record in all three boreholes. Predicted timespans of these intervals yield similar results of ~800-1100 ka for all three boreholes and might provide a new benchmark for progressive improvement, especially for cyclostratigraphic analyses of the Lower Aalenian Opalinusclay Formation.
Total Electron Content Variations during an HSS/CIR driven storm at high and middle latitudes
Authors: Geethakumari Gopika Prasannakumara Pillai , Aikio Anita , Cai Lei , Vanhamaki Heikki , Pedersen Marcus , Coster Anthea , Marchaudon Aurelie , Blelly Pierre-Louis , Haberle Veronika , Maute Astrid , Ellahouny Nada , Virtanen Ilkka , Norberg Johannes , Soyama Shin-Ichiro , Grandin Maxime
Published: March 2022

Magnetic storms are caused by the interactions between the solar wind and the Earth’s magnetosphere. Many studies have been carried out for strong magnetic storms. However, moderate or weak storms and their impacts on the ionosphere are less explored. This study investigates the large-scale and mesoscale structures in ionospheric total electron content (TEC) during a moderate storm (Sym-H index minimum: -63 nT) driven by two interacting solar wind high-speed streams (HSSs) and associated co-rotating interaction regions (CIRs) during 14-21 March 2016. For the solar wind, the IMF Bz minimum is -20 nT and the solar wind speed maximum 612 km/s. The long storm starts with a strong storm sudden commencement (SSC) with a peak close to 19 UT on 14 March 2016. The GNSS/TEC maps are obtained from the Madrigal database. The associated field-aligned currents (FACs) from AMPERE, ionospheric convection maps from SuperDARN, and the O/N2 ratio from TIMED/GUVI are also studied for understanding the physics behind.

The focus of the study is on the changes of TEC at high and middle latitudes and the possible coupling between the two. To better characterize the changes, we subtract from the TEC maps the quiet time background (13 March 2016). Our analysis shows the different responses of TEC changes during the storm initial, main, and recovery phases. During the initial phase, TEC enhancements and depletions are found mainly at high latitudes within the auroral oval and close to the cusp, plausibly associated with auroral precipitation and variations in the upward and downward field-aligned currents (FACs). After the onset of the main phase, the TEC is enhanced at mid-latitudes with a maximum of ~10 TECU. During the main phase, we observe the evolution of a storm-enhanced-density (SED) plume and a transient enhancement of TEC in the polar cap. During the late main and the recovery phases, a strong TEC depletion at high and middle latitudes is found on the dayside and in the evening sector. The depletion is associated with the decrease of the O/N2 ratio indicating upwelling of the neutral atmosphere. The possible physical mechanisms associated with the observed TEC variations will be discussed.
Vehicle damage and transport and possible shock wave formation in the Flateyri avalanche in January 2020.
Authors: Lárusson Ragnar , Hakonardottir Kristin Martha , Hafsteinsson Haukur Elvar
Published: March 2022

Two large dry slab avalanches from the 700 m high mountain above the village of Flateyri, NW Iceland, partly overflowed two deflecting dams on the eve of the 14th of January 2020. While most of the avalanche snow was deflected from the village by two 15-20 m high deflecting dams, approximately 10 % of the total mass overflowed the dams, injuring one person and causing damage to one house, three vehicles and breaking a steel mast, a timber shed and shrub/bush. Radar measurements of the speed of the avalanche, the density of the avalanche deposit, damage to structures, and witness accounts suggest that the avalanche was a transitional avalanche with a 400 m long fluidized head, followed by a denser core, upstream of the dam and the overflow belonged to a fluidized region of intermittent density. It is believed that the sonic speed in such fluidized regions can be one order of magnitude lower than that of air. In such a case the speed of the fluidized region can be comparable to the sonic speed within it, giving rise to the possibility of supersonic shock wave formation.

The aim of the current study is to analyze the dynamics of the part of the avalanches that overflowed the deflecting dams, based on the in-situ damage that the overflow caused, and attempt to distinguish between damage that a shockwave would cause and damage that the kinetic energy in the overflow may cause. The focus is on the three vehicles that were hit by the avalanche overflow and transported 13 to 20 m horizontally, two of them over a three to four meters high pile of snow. We find that aerodynamic forces caused by the overflow could have been large enough and lasted long enough to transport the cars the observed distances. The calculations are simplified and effects of an uneven lateral density distribution are omitted. Supersonic conditions in the overflow are considered unlikely.

A moving supersonic shockwave would not have lasted long enough (order of 10-100 ms) to transport the cars. Weak compression shocks in subsonic avalanche flow may form upstream of stationary obstacles, due to the compressibility of the avalanche front. Those would also be too short-lived to contribute to the transport of the vehicles. Damage to brittle objects (with a resonance period in the same range as the pressure wave period, 2 to 100 ms), such as window glass, doors, and non-reinforced concrete walls, can however be contributed to such short-lived impacts and interactions with moving pressure waves.

Shockwave-turbulence interactions are generally known to cause high-intensity noise radiation of various characteristics. Standing shocks, due to supersonic flow upstream of stationary obstacles (e.g. buildings or high cliffs) could be a cause for impulsive sounds observed prior to the arrival of the avalanche.
Towards Late Quaternary sea ice reconstructions in the Arctic with sedimentary ancient DNA. 
Authors: Cordier Tristan , Grant Danielle M. , Steinsland Kristine , Häkli Katja , Blindheim Dag Inge , Weiner Agnes , Larsen Aud , Hestetun Jon Thomassen , Ray Jessica Louise , De Schepper Stijn
Published: March 2022

Sea ice has a pivotal role in the regulation of the Arctic climate system, and by extension to the global climate. Our knowledge of its historical variation and extent is limited to the satellite records that only cover the last several decades, which considerably hampers our understanding on how past climate has influenced sea ice extent in the Arctic. Latest modelling efforts indicate that the Arctic may be sea ice free in summer by 2050, making the appreciation of the effects that such major change will have on Arctic ecosystems of paramount importance. Here, we will present the first results of the AGENSI project (www.agensi.eu) aiming at reconstructing the past sea ice evolution with sedimentary ancient DNA. Based on a large collection of surface sediments collected along multiple gradients of sea ice cover in the Arctic, we show that plankton DNA sinking to the seafloor can be used to predict the variation of surface sea ice cover. Further, we will present our current efforts to utilize this dataset to reconstruct the past sea ice variation in Late Quaternary sediment cores.
Tropospheric Parameter Estimation with Dual-Frequency GNSS Smartphones
Authors: Stauffer Raphael , Hohensinn Roland , Herrera Pinzón Iván Darío , Möller Gregor , Rothacher Markus
Published: March 2022

With the introduction of the operating system Android 7 Nougat in the year 2016, it became possible to access the GNSS code and carrier phase observations on Android smartphones. These observations can now be processed with state-of-the-art GNSS processing software, which allows an in-depth evaluation of the smartphone`s GNSS performance. The availability of the carrier phase observations is an important step towards sub-decimeter-level positioning. Since a few years, there are also smartphones on the market that are equipped with dual-frequency GNSS chipsets.

In this presentation, the capability of dual-frequency GNSS smartphones for the estimation of tropospheric delays is investigated. Static measurements over several weeks are performed using a Google Pixel 4 XL smartphone. The measurements are processed using relative positioning methods in a real-time mode, where a Continuously Operating Reference Station (CORS) acts as a base. The estimated differential tropospheric parameters – derived for short and medium baseline lengths – are then added to the absolute values computed at the reference station by Precise Point Positioning (PPP). Using this method, we demonstrate that the tropospheric zenith total delays can be successfully determined from smartphone observations. When comparing the estimated tropospheric delays with those determined at a nearby geodetic receiver, differences in the range of a few millimeters to centimeters are visible. In view of these accuracies, the suggested method shows the potential to resolve small-scale tropospheric structures and thus, can be an interesting data source for numerical weather prediction models or related GNSS crowdsourcing projects.
Identification of the co-localisation of Hg with Se and Fe by NanoSIMS in sperm whale liver.   
Authors: Paton Lhiam , Angels Subirana Maria , Schaumlöffel Dirk , Feldmann Jörg
Published: March 2022

The biological pathway by which MeHg undergoes detoxifications in some mammals and birds has yet to be fully elucidated. The current understanding is that HgSe nanoparticles (NPs) are formed in vivo as the end point of a detoxification process. Presented, is a contribution to the body of work already present in the field based on recent insights into the existence of HgSe NPs after Hg was detected by NanoSIMS, for the first time, in the liver of a sperm whale that was beached in Ardersier, Scotland. Analysis by NanoSIMS found heterogenous distribution and co-localisation of Hg with other elements including Se and Fe, giving a possible insight into the complex biological mechanism that ends in tiemannite NPs being stored in the livers of whales. 

 

 
Effect of Langmuir circulation on mixing and carbon dynamics in a shallow lagoon
Authors: Voynova Yoana G. , Buckley Marc P. , Stresser Michael , Cysewski Marius , Bödewadt Jan , Gehrung Martina , Horstmann Jochen
Published: March 2022

In fall 2020 and 2021, two field surveys examined the water column dynamics and surface mixing in a shallow lagoon, Szczecin (Stettin) Lagoon, located at the border between Germany and Poland. This was part of a larger experiment, looking into water column and air-sea interactions, and momentum fluxes, but this study is focused on how the presence of proposed Langmuir circulation affects the carbon and oxygen dynamics, and primary production in this shallow lagoon.

Measurements were collected from a station in Szczecin Lagoon, located near the Polish border, with water depth of about 4 meters. Measurements at and around the station were made using mobile FerryBox systems, or Pocket FerryBoxes, which measured almost continuously water temperature, salinity, dissolved oxygen, chlorophyll fluorescence, pH, turbidity, colored dissolved organic matter (CDOM) and in 2021 partial pressure of CO2 (pCO2). In addition, water column measurements of currents (ADCP) and water level were available, as well as surface drifters, and drone aerial measurements.

We found that during low wind conditions, the water column was well-mixed to a depth controlled by expected Langmuir cells, and bottom waters below this depth were quite different in most of the biogeochemical parameters measured. Therefore Langmuir circulation most likely controlled water column structure in large regions of the Szczecin Lagoon, consequently influencing the community, carbon and dissolved gas distributions in this shallow lagoon, and most likely the air-sea gas exchange rate. Only during short storm events, these conditions changed, and the water column structure and concentrations of biogeochemical parameters were altered.
An updated model for generating historic precipitation isotope time series from machine learning applied in Europe
Authors: Nelson Daniel B. , Basler David , Kahmen Ansgar
Published: March 2022

Hydrogen and oxygen isotope values of precipitation are critically important quantities for applications in Earth, environmental, and biological sciences. However, direct measurements are not available at every location and time, and existing precipitation isotope models are often not sufficiently accurate for examining features such as long-term trends or interannual variability. This can limit applications that seek to use these values to identify the source history of water or to understand the hydrological or meteorological processes that determine these values. We developed a framework using gradient boosted regression tree-based machine learning, which we used to implement a procedure for calculating isotope time series at monthly resolution using available climate and location data. Here we present two new updates to our model, Piso.AI, one of which applies the original approach to new climate predictor data to extend the time series to the 1950-2020 time interval, and the second of which uses a restricted set of predictors to allow time series to be generated that span the range from 1901-2020 with slightly reduced accuracy compared to the original model. Both new products can be applied over most of Europe, and were trained on the historic archive of precipitation isotope data available from the Global Network of Isotopes in Precipitation. These model products facilitate simple, user-friendly predictions of precipitation isotope time series that can be generated on demand and are accurate enough to be used for exploration of interannual and long-term variability in both hydrogen and oxygen isotopic systems. These predictions provide important isotope input variables for ecological and hydrological applications, as well as powerful targets for paleoclimate proxy calibration, and they can serve as resources for probing historic patterns in the isotopic composition of precipitation with a high level of meteorological accuracy. Predictions from our modelling framework are available at https://isotope.bot.unibas.ch/PisoAI/.
A UAV-based approach for biomass prediction and sward structure characterization in coastal meadows
Authors: Villoslada Miguel , Bergamo Thaísa , Ward Raymond , Joyce Chris , Sepp Kalev
Published: March 2022

Coastal meadows provide a wide range of ecosystem services (ES) worldwide. Primary production in coastal meadows is a key ecosystem function that drives the supply of ES such as carbon (C) sequestration as well as food provision for livestock. Beyond their role as carbon sinks, high species diversity and complex structure of coastal meadow landscapes comprise an important habitat for populations of wildfowl, waders, amphibians, and arthropods. The quality of these habitats partly depends on sward structural heterogeneity, which is mostly determined by low intensity grazing.

In order to better target conservation efforts in these ecosystems, it is necessary to develop highly accurate models that account for the spatial nature of ecosystem structure, processes and functions. In this study, above-ground biomass was predicted at very high spatial resolution in nine study sites in Estonia. A combination of UAV-derived multispectral and rgb datasets were used to produce vegetation indices and micro topographic models. A Sensefly Ebee UAV equipped with a Parrot Sequoia 1.2 megapixel monochromatic multi-spectral sensor and a senseFly S.O.D.A camera was used to obtain images at 10 cm and 3.5 cm ground sampling distance. A random forest algorithm was used to generate above-ground biomass maps based on biomass samples collected at study sites. The contribution of each predictor variable to the models was subsequently assessed. The models successfully predicted above-ground biomass at very high accuracies.

In order to assess grassland structural heterogeneity, each above-ground biomass map was clustered into discrete sward units using a Large Mean-Shift segmentation algorithm. The clustered above-ground biomass maps were further analysed using a set of five landscape indices that characterize different components of landscape configuration, patch size and heterogeneity. Grassland structural heterogeneity was subsequently related to management history at each study site, showing that continuous, monospecific grazing management tends to simplify grassland structure, which could in turn reduce the supply of a key regulation and maintenance ecosystem services: nursery and reproduction habitat for waders. These results also indicate that UAV-based surveys can serve as reliable grassland monitoring tools and could aid in the development of site-specific management strategies.
Contrasting three evapotranspiration parameterisations for a semi-arid location
Authors: Martínez-Villagrasa Daniel , Cuxart Joan , Martí Belén , Siquier Miquel
Published: March 2022

Data from a research station is used to check the performance of three well-known evapotranspiration parameterisations for a variety of surface conditions. The station is located in the interior part of Mallorca, a Mediterranean island which has a semi-arid climate, with a dry and hot warm season and a cool and humid winter.

The selected parameterisations are i) Priestley-Taylor (PT), which needs net Radiation (Rn) and ground flux (G) measurements and a location-dependent coefficient, ii) Penman-Monteith (PM), which needs as well Rn and G, plus some estimation of the turbulent atmospheric and canopy resistances and, iii) Monin-Obukhov similarity theory (MOST), that relies on at least two measurements at different levels of the atmospheric variables, using an empirical function depending on the static stability. Usually PM and PT have been adjusted to well-watered terrain and mostly provide data for the daily amount of evapotranspiration, while MOST is customarily used at the sub-hourly scale as an estimation of the water vapour flux in numerical models and other applications. The performance of MOST with vapour flux is less robust than the similar ones for the momentum or the temperature fluxes.

In this work we used data from all seasons of the year and compare the estimations of the three parameterisations to the semi-hourly and the daily amounts obtained by an eddy-covariance system, allowing to explore the applicability of PM and PT at the sub-hourly scale and the one of MOST at the daily scale. The estimations are compared to data from an eddy-covariance system and show very different performances depending on the soil water content availability and on the temporal scale.
Dynamical Landscape and Noise-induced Transitions in a Box Model of the Atlantic Meridional Overturning Circulation
Authors: Börner Reyk , Lucarini Valerio , Serdukova Larissa
Published: March 2022

The multistability of the Atlantic Meridional Overturning Circulation (AMOC) challenges the predictability of long-term climate evolution. In light of an observed weakening in AMOC strength, it is crucial to study the probabilities of noise-induced transitions between the different competing flow regimes. From a dynamical systems perspective, the phase space of a multistable system can be characterised as a non-equilibrium potential landscape, with valleys corresponding to the different basins of attraction. Knowing the potential, one can infer the statistics and pathways of noise-induced transitions. Particularly, in the weak-noise limit, transition paths lead through special regions of the basin boundaries, called Melancholia states. Recent studies have applied these concepts to climate models of low and intermediate complexity. Here, we investigate the quasi-potential landscape of a three-box model of the AMOC, based on the popular model by Rooth. We analyse noise-induced transitions between the two stable circulation states and elucidate the role of the Melancholia state. Forcing the model with different noise laws, which represent fluctuations caused by different physical processes, we discuss how the properties of transitions change when considering non-Gaussian processes, specifically Lévy noise. Simulated transition rates are related to their theoretical values using the quasi-potential landscape. Our results yield a comprehensive picture of the dynamical properties of an inter-hemispheric three-box AMOC model under stochastic forcing. By relating the deterministic structure of this simple model to the statistics of critical transitions, we hope to build a basis for transferring this approach to more complex models of the AMOC.
Numerical modelling of pressure-dependent permeability in Bentheim sandstone
Authors: Siegert Mirko , Gurris Marcel , Saenger Erik H.
Published: March 2022

A method for the numerical determination of pressure-dependent permeability in sandstones is developed. The proposed method is restricted to a hydrostatic pressure load that is below the pore collapse pressure.

Our modelling approach is generally based on the idea of digital rock physics. Starting from a µCt-scan, the pore space of a given rock sample is detected and transferred into a numerical model. Subsequently, the stationary Stokes equations are solved, and the permeability is determined from the simulated pressure and velocity fields.

To model the pressure dependence, it is assumed that the deformation of the rock's micro-structure due to pore throat closing has a significant influence on the change in permeability. In our workflow, the respective pore throats between the individual grains of the original CT image are reconstructed using the watershed algorithm and combined in a separate phase of the numerical model. During several simulations, a steadily increasing artificial flow resistance is assigned to the pore throat phase and the respective permeability of the whole sample is determined. Finally, the pressure-dependent permeability curve can be reconstructed via a correlation between flow resistance and pressure load.

The proposed workflow is validated with externally published data of a Bentheim sandstone sample. It is observed that the model is generally able to reproduce the characteristics of a experimentally determined pressure-dependent permeability curve.
Assessment of an ESA CCI Soil Moisture data assimilation framework
Authors: Heyvaert Zdenko , Bechtold Michel , Gruber Alexander , Scherrer Samuel , Dorigo Wouter , Büechi Emanuel , De Lannoy Gabriëlle
Published: March 2022

We present a comprehensive assessment of a land surface data assimilation system, in which microwave-based satellite retrievals of surface soil moisture from the combined active-passive ESA CCI Soil Moisture product are assimilated into the Noah-MP model, using a one-dimensional Ensemble Kalman Filter (EnKF) within the NASA Land Information System (LIS). This data assimilation system produces consistent estimates of surface and root-zone soil moisture, as well as all other geophysical variables, over the European continent from January 2002 to December 2019.

The aim of this study is twofold. Firstly, we explore the impact of design choices and forcing inputs on the skill of the data assimilation system, specifically: (1) the magnitude of observation errors, (2) the bias correction method, i.e., climatological or seasonal CDF matching, and (3) the choice of the meteorological reanalysis dataset used to drive the land surface model. For the latter, we compare the results obtained by forcing the Noah-MP model with the NASA Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2) with those obtained by forcing the model with the European Center for Medium-Range Weather Forecasts (ECMWF) Reanalysis version 5 (ERA5). Secondly, we explore how the data assimilation skill is related to the quality of the satellite retrievals and environmental factors such as land cover, soil texture, and climate.

For both objectives listed above, the skill of the data assimilation system is evaluated by comparing the surface and root-zone soil moisture estimates with in situ observations. Furthermore, we evaluate the behavior of internal diagnostics derived from the data assimilation innovations and increments.

The results display the inevitable trade-off in choosing the observation error magnitude: a smaller observation error will cause the data assimilation to perform worse than an open loop run at some sites, whereas a larger observation error will reduce the skill at well-performing sites. We also show that the bias correction method and the choice of meteorological forcing both have a clear effect on the data assimilation diagnostics, but a negligible impact on the skill of the system that is observed over in situ reference sites. Finally, we show that the skill improvement by the data assimilation framework is strongly related to the quality of the satellite soil moisture retrievals.        

Acknowledgments: this work is part of the ESA CCI+ Soil Moisture CCN1 Scientific Evolution project and the FWO-FWF CONSOLIDATION project.
Evaluating Auroral Forecasts Against Satellite Observations
Authors: Mooney Michaela , Marsh Mike , Forsyth Colin , Sharpe Michael , Hughes Teresa , Bingham Suzy , Jackson David , Rae Jonathan , Chisham Gareth
Published: March 2022

The aurora is a readily visible phenomenon of interest to many members of the public. However, the aurora and associated phenomena can also significantly impact communications, ground-based infrastructure and high-altitude radiation exposure. Forecasting the location of the auroral oval is therefore a key component of space weather forecast operations. A version of the OVATION-Prime 2013 auroral precipitation model was implemented for operational use at the UK Met Office Space Weather Operations Centre (MOSWOC), delivering a 30-minute forecast of the auroral oval location and the probability of observing the aurora.

Using weather forecast evaluation techniques, we evaluate the ability of the operational version of the OVATION-Prime 2013 model to predict the location of the auroral oval and the probability of aurora occurring. We compare the forecasts with auroral boundaries determined from data from the IMAGE satellite between 2000 and 2002. Our analysis shows that the operational model performs well at predicting the location of the auroral oval, with a relative operating characteristic (ROC) score of 0.82. We analyse the model performance in detail during different levels of geomagnetic activity levels and in different spatial locations.
Hydrologic performance of Natural Water Retention Measures: outcomes from the LIFE BEWARE project test site 
Authors: Bettella Francesco , Bortolini Lucia , Baggio Tommaso , D'Agostino Vincenzo
Published: March 2022

The consequences of climate change are exacerbated by land-use changes, which affect the control of rainfall-runoff relations and the impact on flooding hazards. Effectively, urbanization is constantly contributing to the increase of impervious areas and reducing the time-to-peak. The effect of Natural Water Retention Measures (NWRMs) in the mitigation of these phenomena is known. Nevertheless, this kind of sustainable infrastructures are still poorly known by citizens and administrators, and consequently barely adopted in many parts of the European Countries. The LIFE BEWARE project aims to enhance hydraulic safety and spread good practices on rainwater management by promoting and facilitating the adoption of NWRMs in the Altovicentino, a highly rainy foothills area in Northern Vicenza Province (Veneto Region, Italy). In order to support the dissemination activities, some full-scale NWRMs have been realized in the area of intervention of the project. The hydrological functioning of these nature-based green infrastructures is continuously monitored thanks to the installation of devices measuring inlet and outlet runoff. The aim of this research is to present the realized NWRMs and the adopted monitoring system, and to analyze the data collected during the firsts two years. Results show that at this field-scale experiment all the monitored interventions were able to manage almost all the rainfall events occurred during these two years and the fraction of the rainfall runoff that reached the outflow was always less than 2%. Finally, the research provides insights in better understanding the behavior of NWRMs exposed to different weather and environmental conditions. This also adds some useful information at the design phase of such green infrastructure.
P-band SAR for deformation surveying: advantages and challenges
Authors: Xu Yuankun , Lu Zhong , Kim Jin-Woo
Published: March 2022

To date, mainstream SAR (Synthetic Aperture Radar) systems dominantly operate in X/C/L bands (wavelengths of 3.1–24.2 cm), which commonly experience low coherence and thereby degraded InSAR accuracy over densely vegetated terrains. The long wavelength (69.7 cm) P-band SAR, in contrast, holds the potential to address this challenge by penetrating through dense forests to collect highly coherent data takes. Here, we experimented using the NASA JPL (Jet Propulsion Laboratory)’s P-band AirMOSS (Airborne Microwave Observatory of Subcanopy and Subsurface) radar system to acquire repeat-pass SAR data over diverse terrains (14 flight segments) in Washington, Oregon, and California (USA), and comprehensively evaluated the performance of P-band InSAR for ground deformation surveying. Our results show that the AirMOSS P-band InSAR could retain coherence two times as high as the L-band satellite ALOS-2 (Advanced Land Observing Satellite-2) data, and was significantly more effective in discovering localized geohazards that were unseen by the ALOS-2 interferograms in forested areas. Additionally, P-band InSAR could better avoid phase aliasing to resolve high-gradient deformation. However, despite these advantages, P-band InSAR were less sensitive to subtle deformation than X/C/L band radars and faced similar challenges posed by waterbodies, thick snow covers, shadow and layover effects, and the side-looking configuration. Overall, our results suggest that P-band InSAR could be a revolutionary tool for measuring relatively high-gradient deformation under dense forest canopies.   
Assessing diversity and inclusion within the UK’s geochemistry academic workforce
Authors: Anand Pallavi , Appiah Francis , Lawrence Anya , Bots Pieter , Gagnon Jessica , Bhagwat Shonil , Riches Amy , Little Susan , Maters Elena , ChiFru Ernest , Ngwenya Bryne
Published: March 2022

Geochemistry is applied across Earth, environmental and planetary geoscience research. Yet, the first specific workforce diversity data for geochemistry is only now being collected (e.g. EAG-GS led 2022 Global Geochemistry Community Survey). Additionally, national effort is underway to scrutinise detailed and intersectional diversity data (e.g., race, ethnicity, gender identity, sexual orientation, disability, socioeconmic background, career path) for UK geochemists via ‘Evaluating Diversity and Inclusion within the (geochemistry) Academic Ladder (E-DIAL)’, a project funded by the UK’s Natural Environmental Research Council. This project will also collect data to evidence workplace structures and policies specific to the UK’s geochemists.

We will present key findings linked to the geochemistry workforce, including laboratory support staff, from among our survey results to provide a snapshot of the demographics and intersectional representation among the UK geochemistry community within Higher Education Institutes (HEIs). An important facet of this work is our focus on how the allocation, accessibility, and support of geochemistry laboratories are distributed and experienced by all members of the UK community. Furthermore, the study will report on salient aspects of COVID-19 generated impacts and inequities within the geochemistry community. We also present specific findings for experiences that capture evidence of some persisting barriers to individuals and/or geochemistry groups. These exclusionary hurdles include cultural and other obstacles for which we suggest remedies that will advance the representation and further the success of people of minoritised identities within and across the academic ladder. 

We aim to use our project findings to develop recommendations for policy and structural reforms among UK HEIs. These actions will ensure sustained progress for accessibility in geochemistry, improved career experiences and representation among geochemists, and shall help people of all identities to realise equitable career progression in the short and long-term. These policy developments and reforms are critical to improving diversity and inclusion not only within UK geosciences, but in wider STEM.
Evaluation of ERA-5 reanalysis data with respect to the humidity in the UTLS region, using the in-situ data set IAGOS
Authors: Brast Nils , Reutter Philipp , Spichtinger Peter
Published: March 2022

With their frequent abundance in the tropopause region, cirrus clouds and their potential formation regions, the so-called ice-supersaturated regions (ISSRs), may have a significant impact on the tropopause structure by diabatic processes that result from latent heating, driven by phase transitions and interaction with radiation. This may lead to an alteration of the structure of potiential vorticity(PV), leading to changes of large scale dynamics and the stratosphere-to-troposphere exchange.
One of the most important long-term in-situ data set to study water vapor content at the tropopause level is provided by the European Research Infrastructure 'In-service Aircraft for a Global Overserving System' (IAGOS) (Petzold et al., 2020). Along the flight tracks of commercial passenger aircrafts, atmospheric state parameters and chemical properties of the surrounding air are recorded by compact instrument packages. In general, the cruising altitude of these aircraft ranges between 9 and 13 km, making this data set especially viable for studies of the upper troposphere/lowermost stratosphere (UTLS). However, due to the sparsity of these measurements, IAGOS on its own cannot provide three-dimensional water vapour fields with a high temporal resolution in the UTLS region, which are necessary to gain a deeper understanding of the cirrus cloud life cycle. Instead, we use these measurements to evaluate the quality of the well-known ERA-5 data set with regards to e.g. a seasonal cycle of the vertical distribution of water mixing ratio, the relative humidity and the fraction of ice-supersaturated regions. Additionally, the benefit of the higher resolution of ERA-5 over its predecessor ERA-Interim will be quantified.
Impact of lockdowns implementations on CO concentration in Brazil during March 2020
Authors: Meotti Bianca , Hoinaski Leonardo
Published: March 2022

With the rapid emergence of the novel coronavirus disease 2019 (COVID-19), several lockdowns measures have been used to control the spread of the coronavirus around the world. The restrictions imposed by the lockdowns include partial or complete closure of international borders, schools, and nonessential businesses and, in some cases, restricted citizen mobility. Besides the effect on controlling the virus spread, the associated reduction in traffic and industry has revealed an unprecedented impact on global air pollution. Here we evaluate the impact of the lockdowns on CO concentration in Brazil on a national scale. We use data from Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) to analyze the low, median, and higher concentrations of CO in March 2020 compared to the same month in the last 20 years (2000-2019). In March, many Brazilian states declared public health emergency imposing several partial to total lockdowns. Our results reveal that the lockdowns did not reduce the lowest concentrations, since the 25th percentile from March 2020 was approximately 15% higher than the same period from 2000-2019. We observe a decrease in the 90th percentile values from March 2020 when compared to March 2000-2019, suggesting that the lockdowns reduced the highest concentrations which are strongly related to health effects. The 90th percentile concentration of CO in March 2020 was smaller in 50% of the pixels, representing up to 140% of reduction. Spatially, we have observed the maximum reduction due to the lockdowns in the southern and southeast coast, as well as in Roraima state. Lockdowns have also affected the median concentration of CO, reducing the concentration by 70% for 32% of the pixels. Our results confirm the positive impact of the lockdowns on the air quality in Brazil, contributing to mounting evidence that lockdowns and restricting vehicular activities would be an effective way to control the air pollution.
The Irminger Gyre as a key driver of AMOC variability in the subpolar North Atlantic
Authors: Sanchez-Franks Alejandra , Holliday Penny
Published: March 2022

The Atlantic meridional overturning circulation (AMOC) is key in regulating the global climate system through a large-scale system of currents transporting warm waters northward and cooler waters southward. The Overturning in the Subpolar North Atlantic Program (OSNAP) has been measuring the AMOC directly since 2014, demonstrating that water mass transformation within the eastern subpolar North Atlantic and Nordic Seas dominate AMOC variability in the subpolar North Atlantic. Here, we use OSNAP data to further analyse the AMOC in this region. We find that the North Atlantic Current (NAC) accounts for over 72% of the variability in the upper limb of the AMOC. The easternmost branches of the NAC (over the Rockall Plateau and Trough) account for the majority of the AMOC variability (~38%), even though the westernmost branches account for more than half the mean transport (~10 Sv). The lower limb of the AMOC is found to have a statistically meaningful connection to the circulation in the interior of the Irminger basin, i.e. the Irminger Gyre, accounting for ~38% of the AMOC variability. During the OSNAP time period, a prominent feature of the Irminger basin is a layer of low potential vorticity (PV) in the intermediate water density classes. Further observations (ARMOR3D) show that changes in intermediate water thickness in the Irminger basin are connected to AMOC variability (r = 0.60). We hypothesise a buoyancy-driven mechanism connecting the Irminger Gyre with AMOC variability, where an increase in intermediate water layer thickness in the Irminger basin inhibits the northward recirculation of the Irminger Gyre, leading to a strengthening of the subpolar AMOC.