bluuebunny/crossref_metadata_2025 huggingface dataset:
5 years of pyrogenic HONO plumes observed with IASI
Authors: Franco Bruno , Clarisse Lieven , Theys Nicolas , Hadji-Lazaro Juliette , Clerbaux Cathy , Coheur Pierre
Published: February 2023

Nitrous acid (HONO) plays a key role in atmospheric chemistry as a major source – through rapid photolysis – of the hydroxyl radical (OH), the primary oxidant in the Earth's atmosphere. However, significant uncertainties remain on the spatial and temporal variability of HONO, on its formation pathways in the atmosphere, and on the contribution of its primary emissions over its secondary formation. Recently, spaceborne measurements in the UV-Vis spectral domain, taken in the early afternoon with the S5P/TROPOMI instrument, have provided a first global picture of HONO in fresh biomass burning plumes, demonstrating the importance of satellite data for improving our representation of atmospheric HONO. With daily overpass times in the early morning and early evening, the polar-orbiting IASI/Metop instruments and their global measurements of the Earth's radiance in the thermal infrared, have the potential to contribute to tackling remaining uncertainties on HONO and to complement the TROPOMI measurements.So far detected by infrared satellite sounders in the exceptional 2009 and 2019/2020 Australian bushfires only, we use a sensitive detection method to demonstrate that unambiguous HONO enhancements can also be identified in IASI spectra recorded in concentrated fire plumes worldwide. With this method, we analyse the long, unique observational timeseries (2007-2022) of IASI and we report a 15-year record of fire events in which HONO has been detected. This dataset reveals first that HONO is primarily captured by IASI at the Northern Hemisphere mid and high latitudes, and secondly that the IASI evening measurements allow a significantly higher number of HONO detections than during daytime despite the overall weaker thermal contrast and lower measurement sensitivity affecting such night-time observations. We discuss different factors that can explain these features, such as the sharp intra-day variability of HONO, the links with the diurnal variations and intensity of fires, and the vertical sensitivity of the IASI measurements. We apply a retrieval approach based on an artificial neural network to quantify the vertical abundance of HONO in IASI measurements. For selected fires, we analyse the temporal evolution of the HONO total columns along with TROPOMI data. 
Mid Infrared analysis of Jupiter South Pole from JWST MIRI-MRS observations: Thermo-chemical disturbances caused by auroral activity
Authors: Rodriguez-Ovalle Pablo , Fouchet Thierry , De Pater Imke , Bockelee-Morvan Dominique , Lellouch Emmanuel , Lopez-Puertas Manuel , Briens Prisca , Sinclair James , Hueso Ricardo , Wong Mike , Cavalié Thivault , Roman Mike , Fry Patrick , Fletcher Leigh , Harkett Jake , Melin Henrik , Orton Glenn
Published: February 2023

Jupiter’s Polar Regions host a very strong auroral activity. The Jovian auroras leave their imprint in the ultraviolet spectral region, but also in the Mid-Infrared, which suggests that they can influence the thermal structure by heating up not only the thermosphere, but also the stratosphere by particle precipitation. Some studies suggest that auroral activity also influences the atmospheric chemistry by enhancing or depleting some stratospheric hydrocarbons produced by photochemistry, as well as other components such as HCN. Some hypotheses link these variations with the presence of polar hazes at high latitudes on Jupiter.JWST performed several observations of the Jovian System in 2022, most of them as part of the Early Release Science program 1373 (ERS-1373). One of these observations targeted the South Polar Region. On the 24th of December 2022, two spectrometers on board JWST, NIRSPec and MIRI carried out this observation, covering the spectral range from 1 to 28 μm (with the wavelengths beyond 15 microns completely saturated). Along with this observation, another earlier one was performed on July 2022 (OBS-1022), as part of the commissioning program. This complementary observation only covered the ranges 4.9-5.8, 7.4-8.8 and 11.5-13.5 μm, since it aimed only at testing the pointing of the instrument.Both of these observations allowed us to obtain sufficient spectral and spatial information to map stratospheric temperature and hydrocarbons abundances.We will show a complete analysis of the 1022 dataset. Despite the limited spectral range, we were able to measure stratospheric temperatures at pressures between 10 and 0.1 mbar and map the homopause height. To do so, we first needed to retrieve the homopause height (which determines the methane vertical profile of Jupiter) by a simultaneous analysis of fourteen different models of the atmosphere. We found that the auroral oval leaves an imprint in the stratosphere, creating a warmer region where the auroral oval can be spotted in the UV and IR. The analysis also shows an upwards displacement of the homopause level in the auroral oval, in agreement with previous studies but with a much better spatial resolution. We were also able to retrieve 3D maps of acetylene VMR.Along with this analysis, we will present preliminary results on MIRI 1373 observation. This observation covers the full spectral region from 5 to 28 μm and, hence, it has sufficient information to determine the abundances and distributions of other molecules, such as ammonia, phosphine, ethylene and ethane among others. We will also present processed NIRCam images from the polar region as a support for the spectral analysis.
Extended duration of the budburst period under future climate warming: insights from a model
Authors: Lin Jianhong , Berveiller Daniel , François Christophe , Hänninen Heikki , Morfin Alexandre , Vincent Gaëlle , Rathgeber Cyrille , Zhang Rui , Delpierre Nicolas
Published: February 2023

Spring phenology is a key indicator of the terrestrial ecosystems’ response to climate change. However, most phenological studies only focus on the analysis of the average date of a particular phenological event in tree populations, and largely overlook the variability of this date within the populations, resulting in large uncertainties in projecting phenological change and the stability of community under ongoing climate warming. Here, we constructed a model able to simulate the within-population variability (WPV) of budburst dates in tree populations using budburst data observed from 2000 to 2021, and we used the model to evaluate the response of WPV to climate warming in five temperate deciduous tree species (Carpinus betulus, Quercus petraea, Fraxinus excelsior, Fagus sylvatica and Castanea sativa). The WPV model received support for all five species, with a RMSE of 8.6 ± 2.9 days over validation data, which is near the observation resolution. Retrospective simulations using past climate suggested that the beginning (i.e., date at which 20 % trees burst their buds, BP20) and end (i.e., date at which 80 % trees burst their buds, BP80) of budburst in the population advanced over 1961-2021 of 1.3 ± 0.4 days decade-1 and 1.4 ± 0.4 days decade -1, as a consequence of climate warming. However, the duration of the budburst period (DurBB, time interval between BP20 and BP80) did not change significantly. Using three climate models, we found BP20 and BP80 to occur later by 3.1 ± 1.3 days decade-1 and 3.8 ± 1.5 days decade-1 in populations of Quercus, Fraxinus and Carpinus along the 21st century, which was caused by insufficient chilling accumulation, contrasting with a continuous trend towards earlier budburst by 0.9 ± 0.6 days decade-1 and 0.5 ± 0.7 days decade-1 in Fagus and Castanea. Importantly, the duration of the budburst period (DurBB) in the population was projected to increase in the future, especially for Quercus and Fraxinus, due to a stronger temperature sensitivity of the end of budburst in the population. Furthermore, our model suggests modifications at the community scale, with shifts in the budburst sequence for some species. Our work provides a novel model, simulating the continuity of budburst in tree populations in spring. This phenological model can be adapted to the study of other stages of the tree phenological cycle, which are all of continuous nature in tree populations (e.g., leaf senescence, wood formation etc.). Furthermore, based on this approach, our study projects a delayed, and extended duration of budburst in the population under climate warming for two out of the five species investigated. If confirmed in natura, these differential changes in budburst duration could influence the competition among species in forest communities.
The kids aren’t alright
Authors: Thiery Wim
Published: February 2023

Under continued global warming, extreme events such as heatwaves will continue to rise in frequency, intensity, duration, and spatial extent over the next decades. Younger generations are therefore expected to face more such events across their lifetimes compared to older generations. This raises important questions about solidarity and fairness across generations that have fuelled a surge of climate protests led by young people in recent years, and that underpin questions of intergenerational equity raised in recent climate litigation. However, scientific analyses that explicitly consider the intergenerational equity dimension of the climate crisis are remarkably absent. Our standard scientific paradigm is to assess climate change in discrete time windows or at discrete levels of warming, a “period” approach that inhibits quantification of how much more extreme events a particular generation will experience over its lifetime compared to another. By developing a “cohort” perspective to quantify changes in lifetime exposure to climate extremes and compare across generations, we estimate that children born in 2020 will experience a two to sevenfold increase in extreme events, relative to the 1960 birth cohort, under current climate pledges. Building on this framework, we quantify where and when people start living an unprecedented life, as well as intergenerational differences in exposure to attributable extreme events. Furthermore, using a new water deficit indicator, we uncover spatiotemporal differences in lifetime water scarcity. Our results overall highlight a severe threat to the safety of young generations and call for drastic emission reductions to safeguard their future. Finally, this research is already being used in ongoing litigation (e.g. Duarte Agostinho and Others v. Portugal and 32 Other States), calling for more research in this direction to bolster the upcoming wave of climate lawsuits.
Modelling Impacts of Groundwater Flow on Borehole Heat Exchangers: Lessons Learned from Estonia
Authors: Piipponen Kaiu , Soesoo Alvar , Bauert Heikki , Arola Teppo
Published: February 2023

Production of geothermal energy relies heavily on subsurface properties. In low-enthalpy geothermal regimes, thermal energy extracted with a borehole heat exchanger (BHE) is the subsurface heat conducted from the rock and grout to the BHE fluid. No subsurface fluids are pumped in or out of the BHE system in the process. However, groundwater flow can bring warm or cold fluid from the surroundings which changes the temperature profile in the well and the vicinity and thus it can affect well heat production.The geology in Estonia provides a good opportunity to study the groundwater influence on the BHE systems. In Estonia, several hundred meters thick Lower Palaeozoic sedimentary rock sequence is mostly covered by relatively thin Quaternary sediments, while the underlying Lower Proterozoic crystalline basement rocks occur at depths from 150 m in North Estonia to over 600 m in South Estonia. The main groundwater aquifers are confined to the Palaeozoic sedimentary rocks. In North Estonia, the main groundwater aquifers overlying the crystalline basement rocks are Gdov, Voronka, Cambrian-Vendian, Ordovician-Cambrian, and Silurian-Ordovician aquifers. Those aquifers have different thermogeological and hydrogeological parameters shown by several groundwater hydrogeological and hydrodynamic studies and modelling. Only a few geothermal energy studies have been conducted in the Estonian geological setting and the groundwater effects on the geothermal energy budget on the shallow to medium depth geothermal energy systems have not yet been studied in detail.In this study, we parametrized different hydraulic conditions to compare how the groundwater flow velocity impacts the thermal energy yield of the geothermal system. We modelled single BHEs of lengths of 400 m, 500 m and 1000 m and a BHE field of ten 400 m wells at three sites across Estonia. 400 m wells have a U-tube type heat collector grouted with bentonite clay and the 500 m and 1000 m wells have a coaxial heat exchanger of plastic pipe or a vacuum-insulated tube (VIT), respectively. Our results demonstrate that 1) the thermogeological parameters of the area, such as subsurface temperature and thermal conductivity, are the most significant factor in the thermal energy yield of the wells and 2) at all sites, shallow BHEs are sensitive to the added groundwater flow, whereas 1-kilometer-deep coaxial wells with VIT are the least sensitive to the addition. An interesting highlight is that the increase in the thermal energy yield is not consistent at different locations with the groundwater flow variation. At sites where the aquifers are located deep with respect to the borehole length, an increase in groundwater flow velocity brought more advantages than at sites where permeable layers are distributed more evenly or near the top of the geothermal well.
Systematic production and characterization of artificially produced weak layers of depth hoar
Authors: Schöttner Jakob , Walet Melin , van Herwijnen Alec , Schweizer Jürg
Published: February 2023

Buried weak snowpack layers are a prerequisite for dry-snow slab avalanches, which are responsible for most recreational avalanche fatalities. To assess avalanche release probability and size requires detailed knowledge on weak layer mechanical properties. Natural weak layers exhibit a variety of different microstructures and densities, and thus show different mechanical behavior. Up to now, mechanical properties of snow have been mainly evaluated based on bulk proxies such as snow density, while relevant microstructural characteristics have not been accounted for. To establish a link between the microstructure of weak layers and their mechanical properties, we performed laboratory experiments with artificially produced snow samples containing a weak layer consisting of depth hoar. Growing weak layers artificially allows us to control and investigate the full microstructural parameter range. In addition, the controlled laboratory environment helps improve repeatability and limit the scatter that is inherent in field testing. To evaluate the properties and reproducibility of artificially grown depth hoar samples, we designed a snow-metamorphism box with a regulated heating plate at the bottom to impose a large temperature gradient across our snow sample. We then performed compression tests to measure the strength of the artificial weak layers. We used a mechanical testing machine to measure the peak force at the moment of weak layer failure. With digital image correlation we analyzed the deformation of the sample prior to failure. To establish a link between mechanical properties and microstructure, all samples were additionally characterized with micro-tomography. First findings show that we can produce samples with similar properties with reasonable accuracy and that there is a correlation between the resulting mechanical properties and the applied temperature gradient as well as the duration of the depth hoar metamorphism. Our results will help us improve our understanding of the growth and failure behavior of weak snowpack layers consisting of depth hoar and will ultimately allow us to better forecast avalanche release probability.
Mineralogical control on fault friction and stability: a systematic study on quartz, calcite and muscovite ternary mixtures.
Authors: Ruggieri Roberta , Pozzi Giacomo , Collettini Cristiano
Published: February 2023

During fault evolution different rock types are fractured and sheared within the fault core, producing fault gouges with heterogeneous mineralogical composition. Mineral composition exerts a primary control on fault frictional properties and hence on fault slip behaviour. Understanding the conditions that lead to seismic or aseismic fault slip is of great interest to earthquake hazard assessment both for natural and induced seismicity. Although the effect of single mineral phases is probably the most documented factor in laboratory tests, no clear link has been established to understand how systematic variation of different mineral phases in gouge mixtures influences the macroscopic frictional behaviour.Here we present an experimental study designed to probe the control of mineral composition on fault friction and stability responses. We selected three representative mineral phases, commonly found in fault zones, that are known to have severely different frictional properties: muscovite (phyllosilicate), quartz (granular silicate) and calcite (granular carbonate). Thirty double direct shear experiments were performed using a biaxial rock deformation apparatus (BRAVA) on powders (with grain sizes < 125 µm) of pure minerals and their mixtures at normal stress of 50 and 100 MPa, at room temperature and water saturation conditions. After an initial sliding of 10 mm at 10 µm/s to develop a steady state shear fabric, slide‐hold‐slide sequences (30-1000 s) and velocity steps (0.3-300 µm/s) were employed to evaluate static healing and frictional stability, respectively.Our experimental data indicate that the mineralogical composition of fault gouges significantly affects the frictional strength, healing, and stability with a non-trivial pattern. Increasing phyllosilicate (muscovite) content results in a decrease of the frictional strength, from 0.62 for pure calcite and 0.56 for pure quartz down to 0.33 for pure muscovite powders. This effect is more marked in calcite-rich mixtures rather than quartz-rich ones, possibly due to favourable conditions for fluid-assisted pressure-solution at grain contacts. Calcite-muscovite interaction also favours a reduction of frictional healing and a more marked velocity-strengthening behaviour (promoting stable sliding and fault creep) in comparison to quartz-muscovite mixtures.
Data-Driven and Scaling Factor methods of GRACE leakage correction: Can they be reconciled?
Authors: Tripathi Vasaw , Vishwakarma Bramha Dutt , Horwath Martin
Published: February 2023

Time variable satellite gravimetry, realized with the missions GRACE and GRACE-FO, allows for the only global observation of total water storage (TWS) changes. These observations are inherently smoothed due to the upward continuation of the gravity field at the satellite orbits. Additionally, the correlated errors seen as north-south stripes in global maps require further filtering to separate signal from noise. This causes the signal at any region to be biased by signal at neighboring regions, better known as leakage effect. Various methods have been proposed to mitigate leakage and to spatially assign TWS changes at smaller spatial scales than the satellite data is available by using auxiliary information. Unfortunately, there is a large spatio-temporally variable degree of discrepancy in the agreement or the disagreement within these methods, leaving the non-geodetic users of GRACE TWS changes with the complex question of choosing an appropriate method. The scaling factor approach and the Data-Driven Correction (DDC) approach are the most widely used methods. The scaling factor approach uses a numerical model output of TWS changes, whereas the DDC approach uses only GRACE observations to account for leakage.Tripathi et al., 2022 (10.5194/hess-26-4515-2022) found for the Indus basin, that a newly proposed variant of the scaling factor method, called Frequency-Dependent scaling, using the WaterGAP (Water Global Assessment and Prognosis) hydrology model (WGHM v2.2d), produced results with a striking agreement against the results from the DDC approach. Therefore, this contribution extends the comparison of Frequency-Dependent scaling using WGHM v2.2d against the DDC method for 189 global hydrological basins. We achieved an agreement between the results from both methods well within the uncertainties of GRACE TWS observations for almost 85-90% of the global hydrological basins. Such an agreement can bring a much-needed consolidation in the treatment of leakage effect across the user community. The disagreement in the rest of the basins varies across time scales, such as long-term trends and periodic signals, and is being further analysed.
Diagenesis in lacustrine organic-rich shales: evolution pathways and implications for reservoir characteristics
Authors: Yan Yu , Misch David , Sachsenhofer Reinhard , Wang Min
Published: February 2023

Both the primary mineral composition and secondary diagenetic processes may affect shale reservoir characteristics such as effective porosity, pore throat distribution, resulting permeability, wettability, etc. Hence, a better understanding of shale diagenesis is key to the prediction of shale oil and gas resource potential. The first member of the Qingshankou Formation (K2qn1) in the northern part of the Songliao Basin is an organic-rich shale with great source potential. Attempting to characterize the influence of different diagenetic processes active in the clay mineral-rich formation on pore space evolution, 19 sample from the K2qn1 interval (vitrinite reflectance from 0.55 to 1.58 %Ro) were selected and investigated by optical and scanning electron microscopy (SEM). This maturity window covers the hydrocarbon generative and expulsion stages and hence allows to reconstruct the processes active during organic matter (OM) transformation. Interactions of inorganic mineral grains with products of the transformation products of lamalginite-dominated primary OM (i.e., soluble bitumen) and associated pore space changes could be observed at various maturity stages. SEM visible authigenic quartz is present from the oil window up to the dry gas window, mostly in the form of submicron (nm-μm) size microcrystals embedded in the interparticle pores between clay minerals. Euhedral and subhedral quartz types are occasionally visible in mineral dissolution pores and OM-hosted pores associated with post-oil solid bitumen. Authigenic clay minerals (such as chlorite) are visible along the whole maturity range, but predominantly form in interparticle and OM-hosted pores at maturity levels >1.1 %Ro. Solid bitumen impregnations are often associated with authigenic minerals, forming rims along crystal boundaries. This indicates that the mineral precipitation may be associated with fluid compositional changes which occur during hydrocarbon generation (e.g., formation of water-soluble organic acids, etc.). According to the SEM observations, clay mineral-associated interparticle pores are the main storage space for bitumen in the K2qn1 source rock reservoir. These pores may be occluded at early to peak oil window maturity and re-opened at post-oil window maturity due to the expulsion of main parts of the generated hydrocarbons (pyrobitumen stage). This highlights that hydrocarbon generation and expulsion are key factors in porosity development both with respect to organic (bitumen generation) and inorganic (e.g., authigenic quartz precipitation) transformation reactions.
The benefits of Open Science approaches when teaching hydrology
Authors: Schymanski Stan
Published: February 2023

Open science is commonly associated with open access publications, and FAIR (findable, accessible, interoperable and reusable) data. Open source code is progressively being considered an essential component of open science, too. However, even if all these ingredients are available and openly accessible, it is often impossible to reproduce the graphs in a paper from the data and code provided. Which script was used on what part of the data to generate a given plot? Which version of a cited database was used, and what query to extract the presented data points? Moreover, even the basic steps of a scientific analysis, i.e. the derivation of mathematical equations, are often not traceable. Ever came across the famous “it follows that”, where, what follows, contains variables that were not present in the preceding equations?Here I present part of a hydrology course based on a framework designed to address many of the above challenges. It is based on the open-source RENKU platform and deployed in a Jupyterhub instance at https://renkulab.io. RENKU enables the tracking of datasets and their versions, and records executions of code with their respective input and output files, producing a knowledge graph of the entire project and enabling the user to easily re-do all necessary steps to update relevant results whenever a data or code file is updated. RENKULAB uses the docker system to help reproduce the computational environment needed to re-execute the analysis. This greatly facilitates collaborative research and learning, as it removes the need for collaborators and students to recreate the computational environment in their local systems. Integration of GITLAB in RENKULAB facilitates student feedback and collaborative problem solving through issue tracking, where students can gain points by submitting meaningful issues and helping others.The course also uses an open source package for mathematical derivations (ESSM, https://essm.readthedocs.org), which is based on the Python package Sympy, and facilitates clear definitions of variables including their dimensions and units, and dimensionally consistent fundamental equations. These can then be used to deduce derived equations by automatic solving of systems of equations for unknown variables, derivatives, integrations, and many other mathematical operations contained in Sympy. The package combines graphical depiction of equations, as seen in papers, with computational reproducibility of derivations and transparent re-use of equations in numerical code.By employing Open Science approaches from the start, students become naturally accustomed to reproducible research and can use the skills they learn in any professional environments, as they are not bound to proprietary software that their future employers and collaborators may or may not have purchased licenses for.
Adjoint Tomography of the Italian Lithosphere
Authors: Magnoni Federica , Casarotti Emanuele , Komatitsch Dimitri , Di Stefano Raffaele , Ciaccio Maria Grazia , Tape Carl , Melini Daniele , Michelini Alberto , Piersanti Antonio , Tromp Jeroen
Published: February 2023

The evolution and state of geological structure at Earth’s surface is best understood with an accurate characterization of the subsurface, where fluid distribution plays a key role. We present high-resolution seismic tomographic images of tectonic and geological features of the Italian lithosphere based on ground motion recordings and obtained through an iterative procedure. Enhanced accuracy is enabled by state-of-the-art three-dimensional wavefield simulations in combination with an adjoint-state method. The resulting tomographic model characterizes the subsurface structure in terms of compressional and shear wavespeed values at remarkable resolution, corresponding to a minimum period of ~10 s. As primary findings of our work, images of the lithospheric structure in Central Italy are consistent with recent studies on the distribution of fluids and gas (CO2) within the Italian subsurface, allowing us to infer the presence of deep melted material that induces shallow gas fluxes, or traps and deep storage of gas that can be correlated with seismicity. We illuminate Mt. Etna volcano and support the hypothesis of a deep reservoir (~30 km) feeding an intermediate-depth magma-filled intrusive body, which in turn is connected to a shallow chamber. We also investigate the intriguing features of the Adriatic plate offshore of the eastern Italian coast. Tomographic evidence reveals a structure of the plate made of two distinct microplates with different fabric and behavior, and separated by the Gargano deformation zone, indicating a complex lithosphere and tectonic evolution.
Behaviour of Coincya transtagana (Cout.) Clem.-Muñoz & Herm.-Berm., an Iberian endemism in the area of the abandoned mine of Aparis
Authors: Caperta Ana D. , Couchinho Filipa , Abreu Maria Manuela
Published: February 2023

The rare endemic species Coincya transtagana (Cout.) Clem.-Muñoz & Herm.-Berm (Brassicaceae) is distributed in the southwest of the Iberian Peninsula, in Alentejo, Algarve and Andalusia. This species has a strong association with copper mining areas in Baixo Alentejo, including the Aparis mine, in Barrancos. However, it is still unknown if this species is an indicator of metals in the soil (metallophyte). This study aims to investigate the behavior of this species in soils rich in potentially toxic elements. To this end, soil samples and plants were collected in the Aparis mine, and soils’ physicochemical and multi-elemental characterization, and enzymatic activities (dehydrogenase, β-glucosidase, cellulase, acid phosphatase, urease, and protease) were evaluated. Plant biomass was determined, and plants’ chemical multielemental analysis was carried out. The results showed that the soils had slightly basic pH values and not saline, poor in mineral N, with medium to high organic matter concentration, low C:N ratio, medium cationic exchange capacity, and normal Fe, Mn, and Ca concentration. In the soils, the concentration of Zn and Cu was above, and K and Mg were below the values favorable to the good plant development. Dehydrogenase had the highest enzymatic activity whereas protease had the lowest activity. The samples in which C. transtagana had higher biomass corresponded to soil samples where the soil has higher quality. Among the potentially toxic chemical elements studied, Cu is the element with the highest concentration in both soils and plants. The plants present accumulative and non-accumulative behaviors, being considered an accumulator of Mo and S, as well as tolerant to the elements Ni and Zn. In conclusion, our findings showed that this species is well adapted to the mine soil, regardless of the contamination at the local. Further studies are required to test the potential of C. transtagana for potentially toxic soil elements phytostabilization.

 
Performance evaluation of ICESat-2 laser altimeter data for retrieving plant area index
Authors: Guo Da , Hu Ronghai , Song Xiaoning
Published: February 2023

Canopy spatial structure plays an essential role in ecosystem function and the carbon cycle. The Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) provided continuous three-dimensional sampling observation that can be used to derive canopy structure parameters. Although ICESat-2 data is delivering global estimates of forest structure, analysis of the performance of ICESat-2 data across a range of forest conditions remains limited. Therefore, the overall goal of this study was to evaluate the structural estimates of plant area index (PAI) from ICESat-2 data over temperate deciduous forest structural types. The PAI was derived using the geolocated photon data (ATL03) and the segment-based path length distribution method based on 100-m ICESat-2 vegetation product data (ATL08) segments. The ground-measured data used to evaluate the accuracy of PAI inversion at 100-m ATL08 segments was collected in the Saihanba forest reservation, northern China, which was covered by temperate deciduous needle-leaved forest. The results showed that the ICESat-2 PAI was in good agreement with ground-measured data, which indicated that the method had a better performance in retrieving PAI with ICESat-2 data. Moreover, we compared the effects of the characteristic of signal photons in the segments on the accuracy of PAI inversion and found that the accuracy of PAI inversion was limited by the quality of signal photons. Findings from this study highlight the method for estimating PAI with ICESat-2 data that may be suitable for a range of cover types.
A new approach to quantify the reliability of Electrical Resistivity Tomography (ERT) images
Authors: Gautier Maxime , Gautier Stéphanie , Cattin Rodolphe
Published: February 2023

Anthropogenic and natural hazards assessments need a good knowledge of the structures. A classical approach based on geological observations or soil mechanics investigations is often insufficient to characterize both the structures and the nature of subsurface materials. For several decades, near-surface geophysical methods have been integrated into a multidisciplinary strategy to improve the characterization of small-scale features of the subsurface. Electrical Resistivity Tomography (ERT) is a standard approach among these methods. This technique has several advantages, including easy deployment in the field and sensitivity to lithology, fluid contents, or chemistry. With this method, it is possible to detect and characterize the geometry of sliding surfaces on landslides and actives faults. It is also possible to set a permanent survey and obtain time-lapse images to describe temporal changes of resistivity within the subsurface and investigate dynamic processes, such as groundwater flows or soil moisture variations.The ERT method consists of recording apparent resistivity data and inverting them to map the resistivity distribution at depth and to capture possible time changes. Many softwares, such as  Res2DInv, R2, or PyGimli, are now available to carry out the inversion. However, the quality assessment of the obtained models remains an open and challenging question. Indeed,  the robustness of the ERT results depends on factors such as the acquisition geometry, data error,  the resistivity contrast in the subsurface, the inversion procedure, and its parametrization. To overcome these limitations and allow a more accurate interpretation of the ERT models, we propose a new approach for assessing the reliability of ERT images. We propose a new algorithm called PySAM (Python Sensitivity Approach iMprovement) based on the open-source library PyGimli. This new tool provides relative and absolute error assessment on resistivity images from any ERT inversion software. We first illustrate the relevance of this new tool from synthetic tests associated with a well-contrained resisvity model. Next, we revisit the ERT image of the Topographic Frontal Thrust (TFT), a major active fault located in South Central Bhutan, and discuss its geometry which is a crucial parameter to discuss strain accommodation, and improve the seismic hazard assessment in Nepal, Bhutan, and northern India, one of the most densely populated regions.
Biodegradation potential of fenthion and disulfoton on inoculated biochar through alluvial Danube sediment
Authors: Maletić Snežana , Jevrosimov Irina , Kragulj Isakovski Marijana , Tamindzija Dragana , Volaric Ana , Apostolovic Tamara , Roncevic Srdjan
Published: February 2023

Increased pesticide uses over the last few decades raise a serious threat to environment, especially to the groundwater the most important drinking water resource. This work investigates the biodegradation potential of two selected organophosphorus pesticides, OPPs (fenthion and disulfoton) on Danube alluvial sediment in the presence of microbially inoculated biochar (BC). The investigated BC was produced by slow pyrolysis of the Miscanthus giganteus at a temperature of 400°C. Bacillus megaterium BD5 was isolated from the alluvial Danube sediment sample and was successfully immobilized on BC in the form of vegetative cells and endospores. The breakthrough curve of thiourea as a nonsorbing substance was symmetrical, indicating absence of physical nonequilibrium processes in porous media. In general, the results indicate that the Rd coefficient for fenthion (Rd=30) is higher than the Rd for disulfoton (Rd=20), but higher biodegradation was observed for disulfoton (λ=6) than for fenthion (λ=4.5). The highest biodegradation could be a consequence of high adsorption on BC and biosorption. Further enhancement of the biodegradation processes could be achieved by integration with bioelectrochemical remediation system, which will be done in the future experiments.Acknowledgment. Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or European Research Executive Agency (REA). Neither the European Union nor the granting authority can be held responsible for them. Grant agreement No. 10105954
Charting the realms of Convective Cloud Organisation using Unsupervised Learning
Authors: Denby Leif
Published: February 2023

The representation of shallow tradewind cumulus clouds in climate models accounts for the majority of inter-model spread in climate projections, highlighting an urgent need to understand these clouds better. In particular, their spatial organisation appears to cause a strong impact of their radiative properties and dynamical evolution. The precise mechanisms driving different forms of convective organisation which arise both in nature and in simulations are, however, currently unknown.We show how the continuum of convective organisation states can be analysed as an emergent  property of the embedding space representation learnt by a neural network through unsupervised learning.  Specifically we will use a technique to extract an estimate of the manifold in a high-dimensional space on which possible states of convective organisation lie.  Through composition of reanalysis and observations onto this manifold we are able to extract the characteristics of the atmosphere which coincide with different forms of convective organisation, and further we are able to map transitions between different states of organisation and study how these develop.We will show results from analysing: a) what the radiative properties of different forms of organisation are, b) what atmospheric characteristics coincide with different forms of organisation and c) what transitions occur when following air-masses along Lagrangian trajectories.  Specifically, we find: a) net radiation changes significantly between different forms of organisation, b) agreement with previous studies on the importance of boundary layer wind-speed and to some degree atmospheric stability, and c) we are able to succinctly capture what transitions occur between regimes.
Implementation of a modelling system for the investigation of the Saronikos Gulf marine ecosystem (Eastern Mediterranean)
Authors: Kolovoyiannis Vassilis , Mazioti Aikaterini Anna , Krasakopoulou Evaggelia , Zervakis Vassilis , Tragou Eleni Anthi , Mamoutos Ioannis , Potiris Emmanouil , Petalas Stamatis , Chatzilaou Christos , Mosiou Kyriaki , Kontoyiannis Harilaos , Paraskevopoulou Vasiliki , Athiniotis Alexandros
Published: February 2023

The coastal marine ecosystem of Saronikos Gulf, a busy Eastern Mediterranean embayment directly impacted by the greater metropolitan area of Greece’s capital, Athens, is examined through a series of state-of-the-art numerical models that address the hydrodynamics (Delft3D-FLOW), the wave regime (SWAN), the biogeochemistry, and pollution related to species of heavy metals and polyaromatic hydrocarbons (Delft3D-WAQ).The study so far has focused on calibrating model components and on reproducing the seasonal thermohaline conditions, known circulation patterns and the variability of biogeochemical constituents (chlorophyll-a, nutrients, dissolved and particulate matter) and pollutant concentrations, focusing on the vicinity of inner Saronikos.The annual cycle ‘Nov 2009 - Oct 2010’ is simulated, forced with atmospheric data from the ERA5 database. Three sets of open boundary conditions data are tested (Mediterranean Sea Physics Reanalysis dataset by Copernicus and two implementations of the ROMS model covering the Aegean and the Eastern Mediterranean respectively), constituting three classes of numerical experiments aiming to optimize model performance. Freshwater discharges from waste treatment facilities and rivers are considered, the latter drawn from the Swedish Meteorological and Hydrological Institute (platform ‘Hypeweb’).Emphasis has been placed in compiling available information on point sources of pollution from the numerous human activities in the vicinity of the study area. These data are used as forcing in the modelling process.A comprehensive dataset of field measurements collected monthly by the Hellenic Centre for Marine Research from a network of ten stations, as well as satellite derived SST data, are used for model validation.This work is carried out within the context of the EMERGE Horizon 2020 project, that develops methodologies to evaluate, control and mitigate the environmental impacts of shipping emissions. For the scope of the project, next steps currently undertaken include the simulation of the Saronikos Gulf status for the year 2018 considering pollutant mass fluxes (a) from shipping emissions as calculated by the Ship Traffic Emission Assessment Model (STEAM) and (b) from atmospheric depositions as calculated from atmospheric modelling, both components from data provided by consortium partners. 
The cluster who came in from the cold: Nonisothermal nucleation in the gas phase is driven by cool subcritical clusters
Authors: Tikkanen Valtteri , Reischl Bernhard , Vehkamäki Hanna , Halonen Roope
Published: February 2023

Nucleation of clusters from the gas phase is a widely encountered phenomenon, e.g. regional air quality and global climate are both directly impacted by particle formation from atmospheric trace gases [1]. Still, the underlying out-of-equilibrium dynamics of this process are not well understood. The classical view of nucleation assumes isothermal conditions where the nucleating clusters are in thermal equilibrium with their surroundings. However, as in all first-order phase transitions, latent heat is released, potentially heating the clusters and suppressing the nucleation. The question of how the released energy affects cluster temperatures during nucleation as well as the growth rate remains controversial.To investigate the nonisothermal dynamics and energetics of homogeneous nucleation, we have performed molecular dynamics (MD) simulations of a supersaturated Lennard-Jones (LJ) vapor in the presence of thermalizing carrier gas. In addition, a previous study of homogeneous nucleation of carbon dioxide in argon carrier gas [2] was revisited for temperature analysis of the growing CO2  clusters. The results obtained from these simulations are compared against kinetic modeling of isothermal nucleation and the classical nonisothermal theory by Feder et al. [3], which also predicts the existence of cool subcritical clusters, and has been quite controversial.For the studied systems, we find that nucleation rates are suppressed by two orders of magnitude at most, despite substantial release of latent heat. Our analyses further reveal that while the temperatures of the entire cluster size populations are indeed elevated, the temperatures of the specific clusters driving the nucleation flux evolve from cold to hot when growing from subcritical to supercritical sizes. This resolves the apparent contradiction between elevated cluster temperatures and minor nonisothermal corrections to the nucleation rate, both often reported in literature, and is in excellent agreement with the theory of Feder et al. Our findings provide unprecedented insight into realistic nucleation events and allow us to directly assess earlier theoretical considerations of nonisothermal nucleation. References[1] M. Kulmala et al., Direct observations of atmospheric aerosol nucleation. Science 339, 943–946 (2013).[2] R. Halonen et al., Homogeneous nucleation of carbon dioxide in supersonic nozzles II: Molecular dynamics simulations and properties of nucleating clusters. Phys. Chem. Chem. Phys. 23, 4517–4529 (2021).[3] J. Feder, K. C. Russell, J. Lothe, G. M. Pound, Homogeneous nucleation and growth of droplets in vapours. Adv. Phys. 15, 111–178 (1966).
Landslide displacement forecasting using deep learning and monitoring data under different slope conditions
Authors: Rosi Ascanio , Nava Lorenzo , Carraro Edoardo , Reyes-Carmona Cristina , Puliero Silvia , Bhuyan Kushanav , Monserrat Oriol , Floris Mario , Meena Sansar Raj , Galve Jorge Pedro , Catani Filippo
Published: February 2023

Accurate landslide early warning systems are a trustworthy risk-reduction method that may greatly minimize human and economic losses. Several machine learning algorithms have been investigated for this goal, underlying the impressive potential in prediction capability of Deep Learning (DL) models. Despite this, the only DL models evaluated so far are the long short-term memory (LSTM) and Gated Recurrent Unit (GRU) algorithms. Several alternative DL algorithms, however, are appropriate for time series forecasting problems. In this research, we evaluate, analyze, and present seven DL approaches for the forecasting of landslide displacement: LSTM, 2xLSTM, bidirectional LSTM (Bi-LSTM),Multilayer perception (MLP), 1D convolutional neural network (1D CNN), GRU, and an architecture build of 1D CNN and LSTM (Conv-LSTM). The study examines four different landslides with varying geographical locations, geological conditions, time step size, and measuring devices. Two landslides are placed in an artificial reservoir scenario, whereas the other two are affected only by rainfall. The findings show that the MLP, GRU, and LSTM models can produce accurate predictions in all four situations, with the Conv-LSTM model outperforming the others in the Baishuihe landslide, which is extremely seasonal. There are no discernible variations in performance between landslides within and outside constructed reservoirs. Furthermore, the study finds that MLP is better suited to forecasting the largest displacement peaks, whilst LSTM and GRU are better suited to forecasting smaller displacement peaks. We feel that the outcomes of this study will be extremely beneficial in developing a DL-based landslide early warning system (LEWS).
Volcanically induced increase in extra-tropical cyclone frequency
Authors: Andreasen Laurits , Corner Joona , Abbott Peter , Sinclair Victoria , Riede Felix , Timmreck Claudia
Published: February 2023

Volcanic eruptions are well known to influence Earth's temperature, however, how eruptions influence the atmosphere's circulation pattern, especially on the scale of everyday weather is poorly understood. Changing Earth's temperature can affect temperature gradients which in turn could affect baroclinicity and hence high- and mid-latitude weather. Yet, to what extent volcanic eruptions do in fact exert  such an influence is not clear.To answer this, we followed two independent lines of investigation: First, we query the Greenland ice-core proxy record for Indications of increased extra-tropical cyclone frequency that correlates with evidence for volcanism. This is done by comparing the storm proxy sea salt (a substance transported to the ice sheet by wind)  with the volcanological proxy sulfur. Secondly, we simulate eruptions with the MPI-ESM1.2 Earth System Model and use the TRACK algorithm to explore how extra-tropical cyclone frequency is affected in the model  experiments. Both approaches suggest that volcanic eruptions impact high- and mid-latitude weather by increasing the number of extra-tropical cyclones especially at higher latitudes. A detailed interrogation of the simulated eruption scenarios suggests that this increase in cyclone frequency is associated with features such as an increase in isentropic slopes and sea-ice extent most commonly found under  colder climate regimes and is the reverse of what one finds in more equable climates such as that projected for the future.