bluuebunny/crossref_metadata_2025 huggingface dataset:
Patchwork structure of continental lithosphere captured in 3D body-wave images of its anisotropic fabrics
Authors: Plomerová Jaroslava , Žlebčíková Helena , Vecsey Luděk
Published: March 2022

Seismic anisotropy, modelled from propagation of teleseismic longitudinal (P) and shear (S/SKS) waves, provides unique constraints on tectonic fabrics and character of past and present-day deformations of the continental lithosphere in different tectonic environments (e.g., Babuška and Plomerová, Solid Earth Sci. 2020). We evaluate body-wave anisotropic parameters (directional variations of velocities or shear-wave splitting) in 3D and invert for three-dimensional structure of the upper mantle (Munzarová et al., GJI 2018) with no limitation imposed on the symmetry axis orientation into the horizontal or vertical directions. Resulting models of the continental lithosphere are based on data from several passive seismic experiments in Archean, Proterozoic and a variety of Phanerozoic provinces of Europe. We emphasize the importance of the three-dimensional approach of modelling anisotropy to be able to detect tilts of symmetry axes in individual domains of the mantle lithosphere. The extent of the domains is delimited by changes in orientation and strength of anisotropy. Assuming only azimuthal anisotropy, similarly to only isotropy, may create artefacts and lead to spurious interpretations (e.g., VanderBeek and Faccenda, GJI 2021). Prevailingly sub-horizontal preferred orientation of olivine, the most abundant mantle mineral, arises from mantle convection in newly formed oceanic lithosphere on both sides of the mid-oceanic ridges. Systematically oriented dipping fabrics in domains of the continental mantle lithosphere reflect series of successive subductions of ancient oceanic plates and their accretions enlarging primordial continent cores. Consequent continental break-ups and assemblages of wandering micro-plates preserve “frozen” anisotropic fabrics and create patchwork structures of the present-day continents.
The Moon as a Tool for the Calibration of HIRS
Authors: Seibert Constanze V. , Burgdorf Martin J. , Bühler Stefan A. , Müller Thomas G.
Published: March 2022

Observations of the Earth’s atmosphere with sensors on a polar orbit employ a two-point calibration using a cold and a hot reference point. The hot reference point is an on-board blackbody target. The cold reference point is the deep-space view. In case of the moon being in the direction of the deep-space view, it provides an additional calibration target.

The infrared-relevant surface properties of the moon are well known. This allows to calculate the temperatures of the sun-illuminated parts for the different helio-centric distances (0.981 ... 1.019 au). The integration over the satellite-centric visible parts of the surface gives the total lunar flux at each HIRS observing epoch. The HIRS instruments have seen the moon under very different phase angles (typically between half moon and full moon) which makes it possible to monitor their performance over a very large range of flux values.

Analysis of calibration scans of High-resolution Infrared Radiation Sounder (HIRS) on various satellites, which are “contaminated” by the moon, helps to characterize and intercompare the performance of the sensor. We investigated both geometric and radiometric aspects. Among the former we focused on the instantaneous field of view of the various channels, which is sometimes misrepresented in documents and web pages, and compared the values from ground tests to those obtained in flight. We found that the field of view varies slightly with wavelength, and as well between short-wave and long-wave channels. Then we measured the disk-integrated flux at a variety of phase angles to provide observational constraints on a radiative model of the moon (Müller et al. 2020). Such a model is needed to compare directly the flux calibration of future HIRS-like sensors to those that were operational decades ago.

The HIRS instrument has been mounted on various satellites since 1975. By establishing the Moon as an absolute flux standard, it will become possible to clear climate data records from artificial, non-climatic effects that are common to all instruments of a certain type and that can therefore not be identified by postlaunch matchups. The long time series of HIRS is very valuable for climate research, in particular the search for trends in tropospheric humidity.
Estimation of soil hydraulic properties and preferential flow at agricultural hilllslope under controlled conditions 
Authors: Defterdarović Jasmina , Filipović Lana , Kovač Zoran , Krevh Vedran , Han Luka , Kodešová Radka , Gerke Horst H. , Filipović Vilim
Published: March 2022

Soil vadose zone is one of the most complex terrestrial systems due to various processes occurring within its boundaries. The first Croatian critical zone observatory SUPREHILL was established to specify subsurface preferential flow and nonlinear agrochemical transport processes. Combining laboratory and numerical methods with extensive sensor-based equipment will result in a wide range of data allowing us to accurately estimate heterogeneities on a local scale. The presented study includes estimation of soil hydraulic properties (SHP) and water flow experiments under controlled conditions. Undisturbed soil cores (250 cm3) were taken in three repetitions at the top, middle and the bottom of the hillslope to estimate SHP using the HYPROP and WP4C techniques. Undisturbed soil columns were taken at the hilltop, middle, and the bottom of the vineyard hillslope from the row and interrow area. Soil columns are 25 cm high and 16 cm in diameter with soil moisture sensors and tensiometers set inside each column. Each soil column was irrigated three times per day during two-week period. Results obtained using HYPROP showed very similar SHP in the investigated depth which indicates uniform soil structure along the hillslope (top soil layer). HYPROP derived SHP showed very low values of hydraulic conductivity, but the sensors in columns reacted shortly after irrigation which indicates higher hydraulic conductivity. Since soil cores for HYPROP are relatively small compared to the soil columns, the presence of preferential flow is minimal, and some flow pathways present on the larger scale are not accounted for. Therefore, preferential flow will be further identified and quantified using a dye tracer, and experimental results will be shown. For additional preferential flow identification and quantification, later in the research, we will combine CT-scanning of undisturbed soil columns and numerical simulations.  
Sensitivity experiments with ICON-ART for the Andreas hail storm on the Swabian Jura
Authors: Frey Lena , Hoose Corinna , Kunz Michael , Miltenberger Annette , Kuntze Patrick
Published: March 2022

The prediction of hailstorms is highly uncertain, not least since various processes involved act on different scales. We investigate the representation of hail events in the numerical weather prediction model ICON coupled with the aerosol module ART (ICON-ART). Furthermore, we evaluate the relative contributions from aerosols, microphysical parameters and environmental conditions to the uncertainty in cloud-, precipitation- and hail parameters for severe hail events.

Our case study investigates the Andreas storm on the 28th of July over Southern Germany, causing severe damage. We perform model simulations on cloud-resolving scale and compare the model output with satellite and radar observations. The focus of our analysis is on the representation of storm tracks, total precipitation and the hail production rate in the model. 

Also, we are in the process of developing a statistical emulator. In order to identify possible input parameters for the emulator, sensitivity simulations with the model have been performed. Five input parameters have been selected, namely the CCN and IN concentrations, the riming efficiency, the CAPE and wind shear. The model response to changes of these sensitivity parameters will be presented. Further, we will present first results from the ensemble model simulations, which will be used to build the emulator.
Improved monitoring of subglacial lake activity in Greenland
Authors: Bahbah Nielsen Rasmus , Sandberg Sørensen Louise , Bjerregaard Simonsen Sebastian , Havelund Andersen Natalia , Munck Solgaard Anne , Bjørnholt Karlsson Nanna , Bowling Jade , Leeson Amber , Maddalena Jenny , McMillan Malcolm , Gourmelen Noel , Horton Alex , Wessel Birgit
Published: March 2022

Subglacial lakes may form beneath ice sheets and ice caps, given the availability of water and appropriate bedrock and surface topography to capture the water. On a regional scale, these lakes can modulate the freshwater output to the ocean by acting as reservoirs that may periodically drain and recharge. Several such active subglacial lakes have been documented under the Antarctic ice sheet, while only a few are observed under the Greenland ice sheet. The small size of the hydrologically active subglacial lakes in Greenland compared to those in Antarctica, puts additional demands on our mapping capabilities to resolve in great detail the evolving surface topography over these lakes to document their temporal behavior. Here, we explore the potential of combining CryoSat-2 swath data and high resolution DEMs generated from TanDEM-X scenes and ArcticDEM strips to improve our knowledge of the evolution of four active subglacial lake sites previously documented in the literature. We find that the DEM data complement each other well in terms of time and resolution and thus provide new information about the subglacial lake activity, though the small size of the collapse basins is challenging for CS2, and we are only able to derive useful CS2 data for the two largest of the four investigated lakes. Based on these data sets we can e.g. conclude that the collapse basin at Flade Isblink was actually as deep as 95 m when it formed, which is 30 m deeper than previously documented.  We also present evidence of a new active subglacial lake in Southwest Greenland.
Trace Gas Fluxes in an Alpine Urban Setting
Authors: Graus Martin , Lamprecht Christian , Stichaner Michael , Chebanova Darina , Ward Helen C. , Karl Thomas
Published: March 2022

The Innsbruck Atmospheric Observatory (IAO) – established in 2017 – allows for the measurement of the turbulent exchange of inert and reactive trace gases 42m above ground level in the central urban environment of Innsbruck. IAO provides the means for a top-down quantification of pollutant emissions studying their main drivers under various meteorological conditions and flow regimes typical for an alpine valley. The complex urban source distribution of reactive trace gases can complicate the comparison with emission inventories. Long datasets are a prerequisite to gather sufficient statistics on the spatiotemporal variation of the emissions. With adequate gap-filling these data provide top-down boundaries for bottom-up emission inventories. This presentation will give an overview on similarities and differences between urban reactive and non-reactive gas fluxes.
CUAS-MPI - A parallelised version of the confined-unconfined aquifer system model applied to the Greenland Ice Sheet
Authors: Kleiner Thomas , Fischler Yannic , Emunds Raban , Oestreich Lennart , Bischof Christian , Schmiedel Jeremie , Sayag Roiy , Humbert Angelika
Published: March 2022

Simulating the hydrological systems underneath ice sheets and glaciers is important for estimating the freshwater flux into the ocean as well as inferring the characteristics of the hydrological system and its impact on ice sheet dynamics. In particular, simulations of the subglacial hydrological system in high temporal and spatial resolution and coupled to ice sheet models are needed to investigate the formation of ice streams. In order to be able to run simulations efficiently, both codes need to be parallelised. To this end, we present our approach for a parallelised version of the confined-unconfined aquifer system (CUAS) model (Beyer et al., 2018) that was established as a python code. CUAS is simulating an effective porous medium layer, in which the transmissivity indicates if the flow is channelised. Transmissivity is evolving by melt, creep and cavity opening. A fully implicit finite difference scheme is used for the hydraulic head while an explicit Euler time step is used for the transmissivity. 

The new CUAS-MPI version is written in C++ and instrumented for performance measurements. The parallelisation is done with MPI, where we take advantage of PETSc data structures and linear equation system solvers. The code has been designed to be coupled to the Ice Sheet and Sea-level system Model (ISSM) using preCICE (precice.org). 

Pumping tests that are widely used in applied groundwater hydrology are performed to test the model implementation including the boundary conditions and to compare with the analytical solutions. We further present test applications to the Greenland Ice Sheet, with the major focus on performance, rather than on characteristics of the hydrological system.
Morphological behavior of Tremolite subjected to grinding
Authors: Baietto Oliviero , Marini Paola , Zanetti Giovanna
Published: March 2022

The main morphological characteristic, related to the dangerousness of the six minerals defined as asbestos, is the crystallization of the mineral itself with a fibrous habit.

In different geological conditions these minerals can crystallize even with different morphological aspect. The fibrousness of the mineral is fundamental to define its carcinogenicity because, when these fibres are inhaled, they can cause serious diseases.

Different studies has already showed that the grinding of fibrous minerals can showed a decrease in dehydroxylation and breakdown temperatures due to the increase in lattice strain and the decrease in crystallinity.

In this study the answer to the grinding of different Tremolite with different crystal habit are studied. Tremolite, which is classified as carcinogenic substances group 1 by the IARC, is a hydrated calciummagnesium silicate (Ca2Mg5Si8O22(OH)2), belonging to the tremolite-ferro-actinolite series, that can crystallize with two different habits: fibrous, known as asbestiform, or prismatic, known as non-asbestiform.

This decision arises from the need to verify if the tremolite with prismatic habit, if subjected to a grinding process, can produce potentially harmful fibers. These events can happen during natural degradation processes of rocks (weathering of outcrops) or during anthropic intervention, such as the mechanized excavation or earthmoving process (transport).

Following the definition of fiber from the Health and Safety Executive, a dimensional analysis, based on a direct measurement of the particle size (length and diameter), has been carried out. The results of this research indicate that the prevalent morphology of an amphibolic mineral can change habit. Moreover, the production of prismatic components in an amphibolic mineral by means of grinding action (digging or earthmoving), can generally be a safer situation for the exposed subjects, such as workers and inhabitants.
An integrated method for validating spatially non-continuous remotely sensed forest patch dataset for West Africa
Authors: Iheaturu Chima , Wingate Vladimir , Akinyemi Felicia , Ifejika Speranza Chinwe
Published: March 2022

Remote sensing products of medium to high spatial resolution have emerged as promising datasets for environmental modelling and policymaking across scales. Despite the recent increase in their availability and accessibility,  questions often remain on how to best assess the accuracy of these products, since it is pivotal that these be rigorously validated before they are used for scientific investigation and decision making. There are several methods for validating spatially continuous remote sensing-derived products, including comparisons to field surveys, cross-comparisons and verification of physical consistency using reference data. However, there exist few or no validation strategies for validating spatially non-continuous products such as forest patches. In effect, forest patches, as with many other thematic maps, contain information that is discrete, not spatially continuous, and not normally distributed; thus, a validation strategy that makes these assumptions may be inappropriate for such a product. 

We present an integrative approach for assessing the accuracy of a remote sensing-derived product identifying forest patches found within agricultural landscapes of West Africa. The method is based on the well-established error matrix approach and uses a spatial sampling strategy that determines the sample size based on spatial autocorrelation, select sample points based on spatial uniformity and heterogeneity, and assesses the accuracy by comparing sample points and reference data. Compared to other random sampling approaches, ours ensures that a representative sample is used for the accuracy assessment. This representativeness was achieved by utilizing a stratification method that enabled different categories of forest patches across different ecoregions in the map to be included in the sample size. 

While further tests are required, the preliminary results show that our method has the potential to effectively assess the accuracy of forest patches in West Africa and can therefore be adapted for validating other spatially non-continuous remote sensing products.

Keywords: Remote sensing products, Validation, Spatially non-continuous, Error matrix, Spatial sampling, Forest patch, West Africa
Identification and quantification of sources and sinks of carbonyl sulfide
Authors: Zanchetta Alessandro , Kooijmans Linda M.J. , van Heuven Steven , Scifo Andrea , Scheeren Bert , Ma Jin , Mammarella Ivan , Karstens Ute , Meijer Harro A.J. , Krol Maarten , Chen Huilin
Published: March 2022

Carbonyl sulfide (COS) is used as a tracer for gross primary production (GPP) of terrestrial ecosystems and stomatal conductance of leaves. At present, sources and sinks of COS have not been fully assessed, as proven by the poor agreement between the modelled global budget and the most recent measurements. This uncertainty limits both the existing and potential future applications of COS. To understand sources and sinks of COS, the atmospheric station in Lutjewad (53°24’N, 6°21’E, 1m a.s.l.) performs continuous in situ mole fraction profile measurements. Nighttime COS fluxes of -3.0 ± 2.6 pmol m-2 s-1 were determined using the radon-tracer correlation approach. In three occasions between 2014 and 2018, COS enhancements ranging between 100 and 1000 ppt were measured in Lutjewad at 7, 40 and 60 meters above ground level. To identify the sources of these enhancements, both discrete and in situ samples were collected in the province of Groningen to be analysed with a quantum cascade laser spectrometer (QCLS). Several COS sources were identified, such as biodigesters, sugar production facilities and silicon carbide production facilities. These sources were added to the available databases, at a 0.1°x0.1° resolution. To simulate the initial dispersion, they were assumed to spread latitudinally and longitudinally over grids of 0.5°x0.5° width, as bidimensional Gaussian distributions. The updated databases were then combined with a Stochastic Time-Inverted Lagrangian Transport (STILT) model to check the influence of these sources on the Lutjewad measurements. Current results suggest a strong influence on the mole fraction of COS related to air parcels transported from known industrial sources, in particular from the Antwerp (51.2° N, 4.4° E) and Rotterdam (51.9° N, 4.5° E) regions. However, a mismatch still persists and preliminary results suggest that a local influence could explain the gap between modelled and measured COS concentrations. Possibly, COS emissions from these sources fluctuate according to different factors, such as the production rate of a specific facility or particular events. On the other hand, it is also possible that the enhancements in Lutjewad could be explained by scaling up the results to regional, national or international levels, adding similar facilities to the current databases. Nonetheless, these results could provide a useful insight about new sources of COS that could contribute to a more precise assessment of the global budget of this gas species.
Stable isotopes of The River Sava as a tool for transit time investigations: a case study Ljubljansko polje, Slovenia
Authors: Nagode Klara , Pavšek Aljaž , Pavlič Urška , Vreča Polona
Published: March 2022

River water represents the spatial and temporal integrator of the isotopic composition of precipitation in a catchment area. Stable isotope measurements of oxygen and hydrogen (δ18O and δ2H) in stream waters and precipitation are widely applied to investigate hydrological pathways and transit times. In this study, we apply the stable isotope approach to improve knowledge on the hydrological characteristics of the River Sava, Slovenia, by performing monthly sampling of river water at two locations: Brod and Šentjakob and precipitation at one location (Ljubljana–Reactor), between 2020 and 2021. Gathered data was used for preliminary estimations of water transit times in streamflow. Moreover, different methods were used to determine the Local Meteoric Water Line and comparison with precipitation data for the period 1981–2021 to estimate temporal changes and transit times of the River Sava at selected locations.

The climatic characteristics of the investigated area are also reflected in δ18O and δ2H of precipitation that has been monitored since 1981. The δ18O and δ2H values of precipitation reveal strong seasonal variations, while the tracer output signal in the River Sava is dampened. Site-specific long-term (1981–2021) covariation of δ18O and δ2H is also in good agreement with Global Meteoric Water Line (GMWL), while short-period lines (2020–2021) differ in slope and intercept but lie close to the line GMWL. A longer time series is more suitable for the determination of the LMWL, as the error is much higher for shorter two-year periods. 

The exponential flow model produced mean stream water transit times of 4.2 and 3.1 years at Sava Brod and Sava Šentjakob, respectively, whereas estimated transit times were longer compared to the results of previous investigations. Although the identified results are hydrologically plausible, the limitation of this and previous studies are presented as uncertainties resulting from a short sampling period and low sampling frequencies.
The importance of ice nucleation for climate sensitivity in radiative-convective equilibrium
Authors: Gasparini Blaž , Voigt Aiko
Published: March 2022

Large uncertainties persist with respect to the role of microphysical and other small-scale processes in high clouds and their interactions with circulation and convective processes. Moreover, the uncertainty in tropical high cloud feedback is the dominant contributor to the total cloud feedback uncertainty and is believed to be connected to the description of microphysics. A large part of changes in anvil cloud properties is due to changes in ice crystal number and their size, which in turn depend on the background amount of cloud droplet number and ice nucleating particles and the description of ice nucleation.

In this work, we use idealized radiative-convective-equilibrium and tropical limited area experiments with SAM and ICON-NWP models to explore the effect of the number of ice nucleating particles and the number of cloud droplet number concentration on the cloud feedback and climate sensitivity. Moreover, we show that cloud radiative properties are strongly dependent on ice crystal number and size, which can be adequately represented only by two-moment microphysical schemes with an interactive simulation of both hydrometeor mass and number.
A global climatology (2005 – 2020) of sea salt aerosols using MODIS and OMI satellite data
Authors: Mastakouli (1) Elli , Gavrouzou (1) Maria , Korras-Carraca (1,2) Marios-Bruno , Hatzianastassiou (1) Nikos
Published: March 2022

 

Sea salt (SS) are natural strongly scattering coarse aerosols, which yield the largest fraction of aerosol burden over many places on the Earth. They are important to the physics and chemistry of the marine atmosphere, affecting visibility, remote sensing, atmospheric chemistry, and air quality. The production, entrainment, transport and removal of SS aerosol are affected by several meteorological and environmental factors, such as wind speed, surface ocean and air temperature, relative humidity, atmospheric stability, precipitation and sea bottom depth and topography. The key meteorological factor that governs the SS production and life cycle is wind, which causes waves to break, forming whitecaps, thus influencing the injection of SS to upper atmospheric levels and their horizontal transport. Although, most of SS aerosols can be transported with atmospheric circulation only to short distances from their sources, the relatively smaller bubbles can live for a longer time in the atmosphere and thus can be transported not only over oceanic, but also over adjacent continental areas. Sea salt aerosols are highly hygroscopic, adsorbing water, and thus behave as Cloud Condensation Nuclei (CCN), affecting the formation, physical and optical properties of clouds. Therefore, their quantification and spatiotemporal variability is essential for the accurate determination of their climatic ole.

In the present study, SS aerosols are detected on a global scale and for the 16-year period from 2005 to 2020, using a satellite algorithm, which is based on aerosol optical properties. This algorithm uses as input daily spectral Aerosol Optical Depth (AOD) and Aerosol Index (AI) or single scattering albedo (SSA) data from MODIS C6.1 and OMI OMAERUV databases, respectively.  It operates on a daily basis and 1°×1° pixel level and detects the presence of SS aerosols by applying suitable thresholds on Ångström Exponent (AE) (calculated using spectral AOD from MODIS) and AI or SSA. The algorithm outputs the absolute and relative frequency of occurrence of SS aerosols, as well as the associated AOD, on a monthly and annual basis. The results are given on a pixel as well as on regional and global scales. By running the algorithm for each year of the study period, the climatological mean values and the interannual variability and trends of the frequency of occurrence and AOD of SS aerosols are estimated.
The ozone-climate penalty over South America and Africa by 2100
Authors: Brown Flossie , Sitch Stephen , Folberth Gerd
Published: March 2022

Climate change has the potential to increase surface ozone concentrations, known as the ‘ozone-climate penalty’, through changes to atmospheric chemistry, transport and land surface behaviour. In the tropics, the response of surface ozone to a changing climate is relatively understudied, but will have important consequences for air pollution, human and ecosystem health. In this study, we predict the change in surface ozone due to climate change over South America and Africa using data from 3 state-of-the-art Earth system models from CMIP6. To identify the changes driven by climate change alone, we use the difference between the Shared Socioeconomic Pathway 3 7.0 emissions scenario which includes climate change and the same scenario without climate change. The SSP3 7.0 scenario has high emissions of near-term climate forcers and substantial land-use change leading to large temperature changes.

We find that by 2100, there will be an ozone-climate penalty in areas where background ozone is already high, namely urban and biomass burning areas. This includes robust annual mean increases in surface ozone of up to 4 ppb over polluted regions such as the arc of deforestation in the Amazon, with dry season months showing increases of up to 15 ppb. These areas have high NOx emissions from fires, transport or industry. However, models disagree on the role of climate change in remote, low-NOx regions, partly because of uncertainties in NOx concentrations. We also find that the magnitude and location of the ozone-climate penalty in the Congo basin has greater inter-model variation than the Amazon.

We attribute the increase in surface ozone concentration to an increase in the rate of ozone chemical production, which is strongly influenced by the background NOx concentration. As NOx emissions are largely anthropogenic, this suggests that without reduction in emissions, forested areas in urban and agricultural locations are at increasing risk of ozone damage due to climate change. This has implications for the success of secondary forests and other human-modified forests which are mostly located in agricultural areas, deforestation frontiers and forest edges.
Early Triassic Cycling of Pyrogenic Carbon in Northern High Latitudes
Authors: Blattmann Franziska R. , Luz Zoneibe A. S. , Vennemann Torsten , Bucher Hugo , Schneebeli-Hermann Elke , Magill Clayton R.
Published: March 2022

The Permian-Triassic mass extinction (PTME) is considered to be the most severe extinction in Earth’s history. Following this extinction, the Early Triassic is known as an interval of divergent biotic recovery patterns, with several periods of unfavorable environmental conditions as suggested by global fluctuations in carbon isotope compositions of both organic and inorganic carbon reservoirs (e.g., Payne et al., 2004; Galfetti et al., 2007). Despite these global carbon isotope excursions, little is known about the evolution of the organic carbon cycle. The aim of this study is to improve our understanding of long-term organic carbon cycle dynamics, in particular the influence of pyrogenic carbon. Initial results for the Smithian and Spathian from sections sampled in Svalbard show an increase of polyaromatic hydrocarbons (PAHs) during the Spathian. Particularly, phenanthrene and anthracene concentrations increase amid the Smithian-Spathian boundary (SSB). These increases coincide with increased d18Ophosphate values (approx. 14 ‰ to 17 ‰) measured for conodonts in the same locality and are suggestive of a rapid cooling at the SSB. Global temperature decline in the late Smithian would decrease corresponding precipitation intensities, particularly in high latitude regions (Goudemand et al. 2019). Decreasing precipitation intensity generates much less runoff that, in turn, is associated with increases in wildfire activity in high latitude regions (Grosse et al. 2011). Increased wildfire activity may have contributed to increased atmospheric pCO2 levels. In contrast, incomplete combustion of organic matter would also form a recalcitrant terrestrial organic carbon pool, which could act as a carbon sink.
Hydrogen isotopes from lipid biomarkers record eutrophication induced changes in algal community assemblages
Authors: Ladd S. Nemiah , Nelson Daniel B. , Matthews Blake , Dyer Shannon , Narwani Anita , Dubois Nathalie , Schubert Carsten
Published: March 2022

Phytoplankton are an important biogeochemical force, collectively impacting nutrient cycling as well as atmospheric and aquatic chemistry. However, it remains challenging to reconstruct changes in algal productivity and community assembly throughout the geologic past. Here, we lay the foundation for a sensitive proxy of past algal ecology based on compound-specific hydrogen isotope compositions (δ2H values) of common algal lipids. While such measurements have previously been used as indicators of water hydrogen isotope ratios, our results from laboratory cultures and experimental ponds demonstrate that changes in the δ2H values of ubiquitous lipids such as palmitic acid associated with taxonomic changes are an order of magnitude greater than those caused by hydrologic change. These results indicate that δ2H values of algal lipids, and the relative offset of these values among different compounds, can be used to reconstruct past changes in algal community assemblages, including those driven by changes in nutrient supply.

We apply this approach to a ~180 year sedimentary record from Lake Greifen, a lake in the central Swiss Plateau that underwent well-documented eutrophication and partial recovery in the second half of the 20th century. As total phosphorus concentrations in the lake increased from > 100 mg/L to ~ 500 mg/L in the 1950s-1970s, palmitic acid d2H values increased by 40 ‰ and phytol δ2H values by 20 ‰;  δ2H values of both compounds subsequently declined with total P following maximum values in the early 1980s. During this entire time interval, mean annual precipitation δ2H values fluctuated within a ~10 ‰ range and are not correlated with the changes in lipid δ2H values. Additionally, the decline in lipid δ2H values is correlated with declining relative abundance of green algae as the eutrophication pressure on Lake Greifen receded in the past decades. This correlation matches the prediction from our culturing and mesocosm results, where green algae produced exceptionally 2H-enriched fatty acids, and indicates that lipid δ2H can be applied to reconstruct nutrient induced shifts in algal populations.
Is the weather getting "weirder"?
Authors: Jezequel Aglae , Fararanda Davide
Published: March 2022

Climate change has an influence on daily weather. It translates into a heightened public perception of any type of « weird » weather. For example, it has been shown that extreme weather events are seen as pointing towards the reality of climate change. These perceived attributions are not only related to heatwaves, but also to cold spells (Capstick and Pigeon (2014)), and floods (Taylor et al (2014)).

Extreme events however represent only a subset of the weather distribution experienced by the public. Another manifestation of « weird » weather is the succession of very different types of weather in a short period of time, e.g. two following days with a 10°C difference. While this is widely regarded as another manifestation of climate change by the general public, there are only a few studies exploring short timescale weather variability. For example, Cattiaux et al (2015) have found a projected increase in diurnal and interdiurnal variations of European summer temperatures in CMIP5 simulations.

Here, we use the ERA5 reanalyses (1950-2020) over Europe to study observed diurnal and interdiurnal (2, 3, 5 and 7 days) variations of temperature. We focus on extremes (below the 5th percentile and above the 95th percentile of the distribution of temperature differences) for all seasons and independently for each season and calculate trends. While the general result is that, contrarily to popular beliefs, the diurnal and interdiurnal variations have not increased in the observational periods, we show regional differences over Europe and discuss potential explanations for these differences. 

References:
Capstick, S.B., Pidgeon, N.F. Public perception of cold weather events as evidence for and against climate change. Climatic Change 122, 695–708 (2014). https://doi.org/10.1007/s10584-013-1003-1
Cattiaux, J., Douville, H., Schoetter, R., Parey, S. and Yiou, P. (2015), Projected increase in diurnal and interdiurnal variations of European summer temperatures. Geophys. Res. Lett., 42: 899– 907. doi: 10.1002/2014GL062531.
Taylor, A., de Bruin, W.B. and Dessai, S. (2014), Climate Change Beliefs and Perceptions of Weather-Related Changes in the United Kingdom. Risk Analysis, 34: 1995-2004. https://doi.org/10.1111/risa.12234

 
Improved groundwater simulations by multi-criteria calibration of a global hydrological model in the river basins of France
Authors: Hasan H.M. Mehedi , Hsu Kuei-Hua , Eicker Annette , Longuevergne Laurent , Güntner Andreas
Published: March 2022

Groundwater is the most important freshwater source considering its abundance, demand, quality, and accessibility. However, estimation of groundwater storage variations is notoriously difficult due to the lack of information on physical aquifer properties, the connectivity among other water storages, the scarcity of observations at regional scales and high uncertainty associated with the observations if available. In the current study, we tried to improve the simulations of groundwater storage variations of a global hydrological model with a simple bucket-type groundwater module – the WaterGAP Global Hydrological Model (WGHM) – in four French river basins. Sensitive model parameters were calibrated against in-situ streamflow observations and GRACE-based observations of total water storage anomalies in a multi-criterial calibration framework. A regional data set of in-situ observations of groundwater levels and deduced basin-average groundwater storage variations (see Hsu et al., this meeting) was used for validation of the calibration results. In a second setup, the in-situ groundwater observations were introduced as additional observations into the calibration framework.  We found significant improvement in the simulated groundwater dynamics in terms of their seasonal signals and amplitudes after calibration. Overestimated negative groundwater trends in a few river basins caused by overestimated human groundwater use in the original model could also be corrected by the calibration approach. In an additional calibration experiment, specific yield was introduced into WGHM as a new calibration parameter and its calibrated values were compared to those obtained from regionalizing the hydrogeological information.
Geochemical and geophysical characterization of Kalang Anyar mud volcano, Java, Indonesia
Authors: Sciarra Alessandra , Mazzini Adriano , Lupi Matteo , Ascough Philippa , Husein Alwii , Karyono Karyono
Published: March 2022

The northeast sector of Java, Indonesia, is a sedimentary basin hosting several petroleum provinces. This region is characterized by distributed modern and paleo piercement structures, diffused hydrothermal systems, degassing sites and mud volcanoes. Sedimentary volcanism includes the Kalang Anyar mud volcano, one of the active piercements located along the NE-striking Watukosek fault system. This fault system extends from the volcanic arc through the sedimentary basin in the north of the island.

Kalang Anyar covers an area of approximately 1.5 km2 and displays several small seeps scattered over the crater. These seeps discharge mud water, oil, and gas. Several expeditions conducted at the site allowed the acquisition of a multidisciplinary dataset including geochemical, geological and geophysical data. Seismic data highlight the occurrence of drumbeat signals marked by high central frequencies, similar to those found in other mud volcanoes.

Laboratory analyses carried out on the gas released from the seeps show a methane-dominated content with lower quantities of heavier hydrocarbons and CO2, and a marked thermogenic origin. Moreover, CO2 and helium isotopes suggest the presence of mantle-derived fluids that presumably migrate along the Watukosek fault system for tens of kilometers within the sedimentary basin. Water geochemistry indicates that brines are a mix of marine formations waters that interacted with illitizied units.

Carbonate blocks located on the outskirts of the crater zone have been mapped and analysed. These result to be methanogenic carbonates (carbonate cement d13C as low as -48.8) that formed during the microbially-mediated methane oxidation and carbonate precipitation during the offshore activity of the mud volcano. Dating of these blocks indicate that the mud volcano was recently active in sub-aqueous conditions. Kalang Anyar represents a rare example of onshore mud volcanism witnessing the offshore activity and associated precipitation of authigenic carbonates.

Dozens of new settlements have been recently constructed on the flanks and around the crater of Kalang Anyar. This exponentially growing edification represents a common example that may pose in severe danger to the settlements and the residents in case of sudden eruptive activity. The uncontrolled development of the constructions is a geo-hazard that shall not be underestimated.
Correlative, cross-platform microscopy application reveals deformation mechanisms during seismic slip along wet carbonate faults
Authors: Ohl Markus , King Helen , Niemeijer Andre , Chen Jianye , Plümper Oliver
Published: March 2022

Faults in the upper crust are considered major fluid pathways, raising the need for deformation experiments under wet conditions that focus on the nanoscale interaction between gouge material and pore fluid. Friction experiments on calcite at seismic slip velocities show strong dynamic weakening behaviour attributed to a combination of grain-size reduction and nanoscale diffusion. The resulting syn-deformational physico-chemical interactions between fluid and calcite are key in deciphering deformation mechanisms and rheological changes during and after (seismic) faulting in the presence of a fluid phase. We conducted rotary shear deformation experiments (1 m/s, σn = 2 and 4 MPa) on calcite gouge with water enriched in 18O (97 at%) as pore fluid to track and quantify potential fluid – mineral interaction processes. With our correlative, cross-platform workflow approach, we integrate Raman spectroscopy, nanoscale, and Helium-Ion secondary ion mass spectrometry (nanoSIMS, HIMSIMS), focused ion beam – scanning electron microscope (FIB-SEM) and transmission electron microscopy (TEM) to characterise the nanostructure and analyse isotope distribution. Raman analyses confirm the incorporation of 18O into the calcite crystal structure, as well as the presence of amorphous carbon. We identify three new band positions relating to the possible isotopologues of CO32- (reflecting 16O substitution by 18O). In addition, we detect portlandite (Ca(OH)2), pointing to a hydration reaction of lime (CaO) with water. Raman and NanoSIMS maps reveal that 18O is incorporated throughout the deformed volume, implying that calcite isotope exchange affected the entire fault gouge. Based on oxygen self-diffusion rates in calcite we conclude that solid-state 18O – isotope exchange cannot explain the observed incorporation of 18O into the calcite crystals during wet, seismic deformation. Hydration of portlandite and calcite containing 18O, implies breakdown and decarbonation of the starting calcite and the nucleation of new calcite grains. Our results question the state and nature of calcite gouges during seismic deformation and challenge our knowledge of the rheological properties of wet calcite fault gouges at high strain rates. The observations suggest that the physico-chemical changes are a crucial part of hydrous calcite deformation and have implications for the development of microphysical models that allow us to quantitatively predict crustal fault rheology.
A robust deep learning methodology to detect floating macro-plastic litter in rivers
Authors: Jia Tianlong , de Vries Rinze , Kapelan Zoran , Taormina Riccardo
Published: March 2022

Plastic pollution in rivers is a serious environmental concern. To improve the monitoring of floating macro-plastic litter in water, researchers increasingly resort to automatic detection tools based on Artificial Intelligence (AI) for Computer Vision (CV). The most advanced applications feature Deep Learning (DL) methods based on Convolutional Neural Networks (CNN) achieving state-of-the-art performances in standard CV datasets (e.g., ImageNet).

Despite promising initial results, only few studies validated the generalization ability of DL models across different locations, environmental conditions, and instrumental setups. Poor generalization results in the need for a new model for each different setting. This increases the data requirements and limits the applicability. These aspects are essential for practical implementations such as the development of a structural monitoring strategy backed by a reliable AI model.

In this work, we discuss how to develop a robust DL methodology by harnessing recent advancements in AI, such as data-centric AI and semi-supervised learning. We also show the effects of implementing these techniques on the generalization performances of a DL model by employing two different datasets of floating macro-plastic in rivers. The first is a new dataset recorded in a semi-controlled environment featuring a small drainage canal in the Netherlands; the second is a dataset available from the literature, with images from different waterways in Jakarta, Indonesia. The significant diversity among the two datasets grants a sound evaluation of model generalization performances and on the suitability of the proposed methodology for achieving increased robustness.
Refined global atmospheric energy budget from ERA5
Authors: Mayer Johannes , Mayer Michael , Haimberger Leopold
Published: March 2022

Climate change is accelerating, and its implications are getting more severe every year. As the exchange of energy within the climate system plays a major role during this time, it becomes pivotal to track anomalous energy transports. A precise quantification of Earth's energy balance is thus indispensable in order to understand the way climate is changing. 

We report the publication of a novel dataset providing mass-consistent global atmospheric energy and moisture budget terms for the period 1979-2020. The dataset is derived from 1-hourly analyzed state quantities of the fifth major global reanalysis produced by ECMWF using advanced numerical and diagnostic methods. It provides monthly averages of vertically integrated atmospheric water vapour and moist static plus kinetic energy transports on a 0.25° regular grid. The fields are much less noisy than similar quantities from standard ERA5 postprocessing, although they have been calculated at full horizontal resolution (T639). They show sharp gradients along coastal lines and sea-ice edges making them well suited for regional studies. Other possible applications of this dataset are, e.g., the assessment of global atmospheric energy and moisture budgets, evaluation of ocean-to-land energy and moisture transports, and meridional atmospheric energy transports. Furthermore, various surface flux terms can be estimated indirectly, such as freshwater fluxes or net heat fluxes when combined with state of the art top-of-the-atmosphere products such as CERES-EBAF. This dataset is publicly available via the Copernicus Climate Data Store (see "Refined atmospheric energy budget from ERA5").
Differences in the rates and character of the last two glacial terminations and impacts on the following interglacials
Authors: Gasson Edward , Stoll Heather
Published: March 2022

Compared with the intensely studied interval of the last glacial maximum and termination, significantly less attention has been given to the preceding glacial period and Termination 2. This is perhaps understandable as the Greenland ice cores do not stretch this far back in time and the terrestrial record of the ice sheets has in part been lost during the subsequent glacial period. However, there are many questions remaining about how these two glacial intervals differed and whether this was important in driving some of the differences between the last interglacial and our current interglacial. Here I’ll present transient ice sheet modelling results of the northern hemisphere ice sheets through the last two glacial terminations. This work was stimulated by a new speleothem record from northern Spain that records the meltwater-driven d18O anomaly in the eastern North Atlantic and provides an absolutely dated chronology (U/Th) during the penultimate glacial and Termination 2. The character of which differs dramatically from a record for Termination 1 recovered from speleothems at the same site. I’ll discuss some possible reasons for the differences between the two glacial terminations recorded at this site and present model experiments to test these hypotheses and whether this can explain some of the differences between the last interglacial and our current interglacial. 