bluuebunny/crossref_metadata_2025 huggingface dataset:
Elasticity curves describe streamflow sensitivity to precipitation across the entire flow distribution
Authors: Anderson Bailey , Brunner Manuela , Slater Louise , Dadson Simon
Published: February 2023

The rainfall-runoff relationship is often simplistically represented through “elasticity”, defined most frequently as the proportional change expected in average streamflow associated with a 1% change in precipitation over a given time period. Elasticity is typically estimated from the average annual streamflow, but may differ along the flow duration curve, indicating, for instance, that precipitation change has less of an effect on low flows as compared to high flows when particular catchment characteristics are present. We estimate elasticity at multiple points across the annual and seasonal streamflow distributions of 805 river gauging locations in the United States to create elasticity curves which graphically represent the responsiveness of low to high streamflow to precipitation. We show that elasticity curve type (the overall shape of the curve) corresponds closely with water storage and catchment flashiness; curve shape varies independently of the magnitude of response; and that the elasticity curves exhibit a regional pattern. We are further investigating whether elasticity curve shape and elasticity magnitude change over time. This assessment suggests that historical changes in water storage, and groundwater-surface water interaction may have led to substantial shifts in elasticity curves over time. This implies probable underestimation of future streamflow under climate change, unless relevant catchment characteristics are adequately considered 
Semi-enclosed experimental system for coal spontaneous combustion for determining regional distribution of high-temperature zone of coal fire.
Authors: zhao Jingyu , Ming Hanqi , Lu Shiping , Yang Xiaocheng , Xiao Yueyan , Jiang Xinrong , Li Rui
Published: February 2023

Temperature variation and gas generation at different depths and positions in the coal combustion process were studied to determine the propagation and evolution of high temperature regions in the process of coal spontaneous combustion. This study selected coal samples from Mengcun, Shaanxi Province, People’s Republic of China, and developed a semi-enclosed experimental system (furnace) for simulating coal combustion. The thermal mass loss of coal samples under various heating rates (5, 10, and 15 °C/min) was analyzed through thermogravimetric analysis, and the dynamic characteristics of the coal samples were analyzed; the reliability of the semi-enclosed experimental system was verified through the equal proportional method of fuzzy response. The results revealed that the high-temperature zone was distributed nonlinearly from the middle to the front end of the furnace, and the temperatures of points in this zone decreased gradually as the layer depth increased. The apparent activation energy of the coal samples during combustion first increased and then decreased as the conversion degree increased. Furthermore, the proportion of mass loss and the mass loss rate in the coal samples observed in the thermogravimetric experiment was consistent with that observed in the first and second stages of the experiment conducted using the semi-enclosed system. The research findings can provide a theoretical basis for the prevention and control of high-temperature zones in coal combustion.
Turning publications into data – imagining a world of linked hydrologic knowledge
Authors: Stein Lina , Wagener Thorsten
Published: February 2023

As a science, hydrology faces diverse sets of interacting processes combined with a vast heterogeneity of our environment. Ideally, one would be broadly knowledgeable in all processes of the water cycle, including their variations across the planet, but taking such a holistic approach to our science has become problematic due to the vast number of hydrologic case numbers published. More than 25 000 articles were published on the topic of water resources in 2022 alone. Such publication numbers make it impossible to keep up with the current literature, not to mention the knowledge acquired over time.But at the same time, these publications comprise a vast source of information and data that is not being utilised at the moment. For example, we are currently unable to connect our highly localised process knowledge for a broader understanding.One solution that has been discussed in the past is to extend our article metadata to relevant hydrologic information to support search and synthesis of hydrologic knowledge. And there is a wide range of potential metadata that can be relevant: research topic, study location, models used, time period covered, data availability…. In regard to data services, it could be used to link data collections or networks with the models that use that data, the researchers who employ the models, and the publications that summarise the knowledge gained.For this data to be useful and used by the community, it will need a collaborative platform to host this information. We discuss the use of Wikidata, a free, accessible, machine-readable, and editable by all, database, for this task. An added benefit is that Wikidata can easily link to existing data repositories and identification numbers, thus making the concept not only of interest for article metadata but also a potential interoperable approach for data services.
Shaping eco-hydrologic flow regimes at regional scale
Authors: Arrighi Chiara , De Simone Marco , Castelli Fabio
Published: February 2023

The EU Water Framework Directive WFD (60/2000) asks the achievement of a good ecological status of water bodies and requires the definition of ecological flows in Water Management Plans. Ecological flow definition goes beyond the minimum low-flow discharge and is defined as a hydrologic regime suitable for the aquatic ecosystem and preservation of biodiversity. Ecological status is monitored by environmental agencies and is based on the worst among the selected biological indicators (e.g., macroinvertebrate-based indices, nutrients and dissolved oxygen, macrophytes indices etc.). This work examines the hydrologic regimes of water bodies based on (i) monitored ecological status, (ii) water quality/quantity stressors and (iii) water balance computed with a distributed hydrologic model validated against recorded river discharge data. As water stressors climate, morphological alterations, land use, and water management indicators are accounted for in each river catchment. Machine learning classifiers are compared in their capability of predicting a good ecological status based on stressors.  The hydrologic model is used to determine flow duration curves and to extract seasonal patterns and characteristic discharges of river which currently satisfy the WFD requirements. The method is applied to the rivers of the Tuscany region (central Italy), which is part of the Hydrographic District of the Northern Appennines. The results show a significant role of climate and land use parameters in determining a less than good ecological status with a consequent need of dilution of pollutants and higher specific discharges. The different hydrologic regimes in different ecological status conditions highlight the capability of advanced eco-hydrologic modelling to overcome the limitations of the commonly adopted purely hydrologic approaches at district scale.
Near Real-Time Distribution of Ozone in China from 2013 to 2020 and Agricultural Impacts
Authors: Liu Liangke , Geng Guannan , Zhong Junting , Liu Yuxi , Xiao Qingyang , Zhang Xiaoye , Zhang Qiang
Published: February 2023

Air pollution is one of the most important environmental problems in China. As a major air pollutant, ozone (O3) will endanger human health and terrestrial ecosystems. It is of great practical significance to obtain a continuous full-coverage dataset of ozone with high spatio-temporal resolution to conduct mechanism research from its causes, development, diffusion, impact and other aspects. In this study, a 3-stage machine learning model was developed through multiple data fusion, and the LightGBM method is used to obtain the hourly spatio-temporal distribution dataset of the O3 concentration in China from 2013 to 2020, with a resolution of 0.25 °× 0.25°. We first revise the meteorological reanalysis data using ground observation and propose a data fusion algorithm to achieve the ground level distribution of ozone, which combines ground observation of pollutants, population data, revised reanalysis meteorological conditions, reanalysis of radiation, land and vegetation data, emission inventory and results of chemical transport model simulation.  In addition, due to the common phenomenon that the previous prediction models underestimate the extreme value of the pollution periods,therefore, we redefined the heavy pollution event and assimilated it into the 0.25 grid by using the synthetic minimum oversampling technique (SMOTE) method to improve the model performance during the extreme pollution periods.Our model, with the 10-fold CV result of R2 = 71% and RMSE= 25.1μg·m-3, and our hourly O3 concentration results are spatially and spatially continuous with a similar distribution compare to the observation, which proves the reliability of our model. With higher time resolution, various exposure response indicators can be obtained. AOT40 calculated by high-resolution hourly ozone concentration further, which is far more accurate than it when directly predicted by daily indexs modeling.In addition, based on the distribution of AOT40, we assessed the agricultural damage and ecological damage caused by the change of surface ozone pollution during 2013-2020. Our estimation considered the planting area and phenological period of crops that the overestimation of crop RYL in the region can be avoided. The annual avrage production loss of wheat, rice and maize in China from 2013 to 2020 is 55.0, 57.4 and 23.6 Mt, respectively. Besides, The loss of gross primary productivity was also estimated. During 2013-2020, the ozone pollution in China caused an annual average loss of 2.1%, and the loss in the south was much higher than that in the north.
Impact of an isolated summer storm on sea ice and ocean conditions in the Canadian Basin
Authors: Bent Emma , Lique Camille , Sutherland Peter
Published: February 2023

The Arctic Ocean has undergone a rapid decrease of sea ice extent for decades and studies have shown that the storm activity has increased in the Arctic. Regions that are seasonally ice-opened experience a greater forcing at the surface, which affects the upper-ocean through mixing, turbulence and air-sea interactions. Previous studies have shown the local and short term impacts of wind and waves on sea ice through negative or positive feedback mechanisms. For instance, increased air-sea flux during the freezing season can lead to a cooling of the upper-ocean and favor ice formation, while an increase in wind forcing can modify the vertical profile of the mixed layer, leading to melting or formation of ice. Given the potential of the mixed layer properties to be modified locally by an increased wind/wave forcing, we question whether this type of forcing could have a seasonal effect on the mixed layer and therefore on the sea ice.We thus use a 1D coupled ocean-sea ice model (NEMO1D-SI³) to study, in the seasonal ice zone of the Beaufort Sea, the immediate change and the seasonal evolution of the mixed layer when forced by an idealized summer storm. The response of sea ice is also examined. We conduct the experiment for a range of storms varying in intensity, duration and date of forcing. Compared to a situation with no increased forcing, we first find that summer storms thicken the mixed layer through mixing which increases the upper-ocean heat content. In the fall, ice formation is consequently delayed for a maximum of 2 weeks compared to a situation with no increased forcing. Secondly, we show that storm-induced thick mixed layers isolate the sea ice from sub-surface warm waters, allowing for efficient ice growth. Ice is consequently thicker at the end of winter compared to a situation with no increased forcing (maximum difference of 10 cm). Thirdly, we find that these results are amplified for storms that happen earlier in summer and have a strong momentum input to the ocean. Our results suggest that localized storms could be a significant driver of the seasonal evolution of the mixed layer and the sea ice.
Study of deformation and fracture behavior of shale by a novel anisotropic regular lattice spring model
Authors: Xie Qiang , Sun Weichen , Wu Kai , Cao Zhilin , Fu Xiang , Fumagalli Alessio , Ban Yuxin
Published: February 2023

This research aims to study the deformation and fracture behavior of shale by a novel anisotropic regular lattice spring model (ARLSM). The novel ARLSM applies the normal and tangential coupling spring to release the Poisson's ratio limitation in the traditional regular lattice spring model. Meanwhile, a nonlinear strength criterion is introduced into ARLSM to simulate the fracture failure of shale. Two benchmark problems are tested to implement the research. The study shows that ARLSM has larger range of Poisson's ratio and better effects comparing with the existing anisotropic lattice spring model. Moreover, ARLSM can accurately predict the deformation and fracture behavior of shale under different conditions.
Levers of climate pledges influencing the Paris Agreement target
Authors: Tibrewal Kushal , Tanaka Katsumasa , Boucher Olivier , Ciais Philippe
Published: February 2023

Countries pledge GHG mitigation goals in form of near-term emissions targets for 2030, long-term net-zero emissions in mid-century (some countries) and targets for methane emission reductions, towards limiting global warming as stipulated in the Paris Agreement. These undergo regular revisions to strengthen the ambition, with the latest set of revisions occurring during COP26 and COP27. As of December 2022, 169 countries have near-term targets, 56 have long-term targets to become carbon neutral and 150 nations have pledged to reduce their methane emissions up to 30% by 2030.  The end-of-century temperature rise is highly sensitive to the pledges but also to actual extent of implementation of these pledges. Using historical emissions from the PRIMAP-Hist dataset, future emissions of CO2, N2O and CH4 are modelled for each country by incorporating their respective near-term, long-term and methane pledges. Emissions for other climate forcers are assumed to follow SSP4-60. These emission profiles are used as input to simple climate model – ACC2 (Tanaka et al., 2021) to estimate the temperature impacts. With the current pledges, the global temperature rise in 2100 is expected to be 2.0 and 2.1 °C, corresponding to the fulfillment of conditional and unconditional near-term pledges, respectively.  We further explore a suite of emissions pathways to identify some key ‘levers’ across the pledges that can strongly influence the projected global temperature in 2100.  We found that these levers can further reduce the temperature by 0.50 °C or increase by 0.25 °C.  The most significant reductions in temperature rise can be achieved by ratcheting up of the current conditional targets by 10%, shifting the net-zero target year to 2050 for all countries currently having a longer-term goal and adding a net-zero target in 2070 for countries with currently no long-term goals. Inclusion of all these levers can increase the likelihood of limiting temperature rise well below 2 °C and bringing it closer to 1.5 °C. Additional, relatively smaller, contributions accrue from inclusion of Russia, China and India in the Global Methane Pledge. On the other hand, failing to meet even the unconditional NDC targets and delaying the current net-zero targets by 10 years contribute to increases in temperature rise of 0.08 and 0.17 °C. Contributions are also evaluated on a country-by-country basis.ReferenceTanaka K, Boucher O, Ciais P, Johansson DJA, Morfeldt J (2021) Cost-effective implementation of the Paris Agreement using flexible greenhouse gas metrics. Science Advances 7 (22):eabf9020. doi:10.1126/sciadv.abf902
Cloud-radiative heating shapes idealized extratropical cyclones by changing atmospheric stability
Authors: Voigt Aiko , Keshtgar Behrooz , Butz Klara
Published: February 2023

"All models are wrong. Some are wrong in a useful manner.” (adapted by the authors from George Box) In this presentation, we utilize an error in the surface flux formulation of the ICON-NWP numerical weather prediction model to elucidate how cloud-radiative heating affects the intensity of idealized extratropical cyclones.We present idealized baroclinic life cycle simulations with two versions of the global atmosphere model ICON-NWP. Both versions simulate the same cyclone when run without radiative heating, but disagree when cloud-radiative heating is allowed to affect atmospheric temperature and the cyclone evolution. In version 2.1, taking into account cloud-radiative heating leads to a weaker cyclone, while in version 2.6 a stronger cyclone results. The simulations use a new modeling technique for which only cloud-radiative heating interacts with the cyclone and clear-sky radiative heating is omitted. The technique circumvents changes in the mean state due to clear-sky radiative heating that has complicated the interpretation of previous work.A defining difference between the two model versions is the amount of simulated low-level clouds. Compared to version 2.6, version 2.1 simulates twice as many low-level clouds and a twice as strong cooling of the planetary boundary layer by cloud-radiative heating. While the increase in low-level clouds is tied to an error in the surface flux formulation in version 2.1 that was corrected in version 2.6, the error provides an opportunity to probe the impact of cloud-radiative heating in the boundary layer (below 2 km) versus the free-troposphere (above 2 km). Sensitivity studies show that negative cloud-radiative heating in the boundary layer from the tops of low-level clouds weakens the cyclone by making the atmosphere more stable. At the same time, they show that negative cloud-radiative heating near the tropopause from the tops of high-level clouds strengthens the cyclone by decreasing atmospheric stability. The changes in stability are particularly evident in regions of upward motion.Overall, our results indicate that the vertical distribution of clouds and their radiative heating are an important factor for the dynamics of extratropical cyclones and that model differences in the simulation of low-level clouds can translate to model differences in cyclone intensity.
Analysis of Projected Changes in Seasonal Precipitation Amounts for Central Asia Using the CMIP6 Multi-Model Ensemble Approach
Authors: Turp M. Tufan , An Nazan , Demiralay Zekican , Avcı B. Cem , Kurnaz M. Levent
Published: February 2023

Particularly due to its arid and semi-arid nature, the environmental, ecological and socio-economic systems of Central Asia are under serious threat of climate change. Depending on the climate change in Central Asia, water resources spread over limited physiographic regions in the domain, grasslands and related livestock are the elements that will be adversely affected by the negative changes. The vital resource in the arid and semi-arid Central Asia region, which is a kind of large continental rain shadow basin surrounded by mountains, is therefore water. For this reason, in this study, the changes in the total precipitation for Central Asia, which is the core region of the Asia continent and one of the 14 main domains of the COordinated Regional climate Downscaling EXperiment (CORDEX), were examined within the scope of Coupled Model Intercomparison Project-Phase 6 (CMIP6) models. In the study, a multi-model ensemble mean approach was applied in order to investigate the projected changes in seasonal precipitation amounts for three different future quarters (i.e., 2025-2049, 2050-2074, and 2075-2099) with respect to the reference period of 1975-1999 under various Shared Socioeconomic Pathways (i.e., SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5).Acknowledgement: This research has been supported by Boğaziçi University Research Fund Grant Number 19367. 
Relationships between upper mantle thermal structure and crustal deformation in Western and Central Europe – new interpretations of seismic tomography models
Authors: Bott Judith , Scheck-Wenderoth Magdalena , Kumar Ajay , Cacace Mauro , Noe Sebastian , Faleide Jan Inge
Published: February 2023

Mantle shear-wave velocity models derived from seismic full waveform inversion methods reveal a very heterogeneous lithosphere-asthenosphere system beneath intracontinental Western and Central Europe north of the Alps. To better understand the physical state of the upper mantle in this region, we convert shear-wave velocity models to thermodynamically consistent temperature and density configurations using a Gibbs's free energy minimization approach. The inferred physical state of the lithosphere-asthenosphere system is then investigated for its consequences on past and present-day crustal deformation. For instance, a thermal lithosphere-asthenosphere boundary that varies in depth between > 200 km in the southern North Sea and < 80 km close to the Alpine deformation front raises important questions regarding the causes for this thermal disequilibrium and its effects on the thermomechanical stability of the crust. In particular, we will discuss the imaged mantle thermal anomalies in light of the inherited crustal structure and its effects on ongoing deformation (including seismicity) in this intracontinental setting.
Core surface flow variations derived from observatory and satellite magnetic data
Authors: Lesur Vincent , Ropp Guillaume
Published: February 2023

A series of models of the Earth magnetic field and core surface flow are presented. The models were derived sequentially from year 1999 to 2022, using magnetic satellite and ground observatory data. A linear Kalman filter approach and prior statistics based on numerical dynamo runs were used. The core field and secular variation models present the same characteristics as the most recent core field models with slightly higher resolution in time. The core surface flow series of models presents large variations at high latitudes and under the western part of the Pacific Ocean. Filtering out the flow variation periods longer than ∼11.5 years leads to a filtered azimuthal flow with ∼7 years periodicities and patterns propagating westward by ∼60o longitude per year. These patterns are present mainly at mid- and equatorial latitudes. They are compatible with a perturbation of the main flow made of small columnar flows with rotation axis intersecting the core-mantle boundary between 10o to 15o latitudes, and flow speed of less than 5km/y. These columnar flows can be identified at all longitudes, but are particularly strong under the Pacific Ocean or under the Atlantic Ocean from 2005 to 2015.
Biodegradation of formic and acetic acids is a significant atmospheric sink
Authors: Nuñez Lopez Leslie , Amato Pierre , Ervens Barbara
Published: February 2023

Bioaerosols include bacteria that comprise about <1% of the total aerosol number concentration in the atmosphere. In current atmospheric models, bacteria are considered as not being metabolically active during their atmospheric residence time. This assumption is contradicting laboratory studies that have revealed that small organic compounds, such as formic and acetic acids, can be efficiently biodegraded by bacteria found in the atmosphere.Formic and acetic acids are ubiquitous in the atmosphere, constituting main organic acids in the gas and aqueous phases. Their sources are usually dominated by direct emissions from biomass burning, fossil fuel combustion, vegetation, and soil, besides secondary production from gas and aqueous phase photochemistry. Their sinks are usually considered to be limited to wet and dry deposition, and oxidation by radicals (OH, NO3).To explore the potential role of biodegradation as an additional sink of formic and acetic acids, we implemented their biodegradation in cloud droplets in a detailed atmospheric multiphase chemistry model. As opposed to aqueous phase chemical reactions that occur in all droplets, biodegradation only occurs in a small fraction of droplets (~0.1%) taking into account the small number concentration of bacteria cells in the atmosphere.We perform model sensitivity studies to identify atmospheric conditions (e.g., pH, cloud droplet size, processing time), under which biodegradation represents a significant sink of the two acids. Our model results show that the concentration of formic and acetic acids may be overestimated by up to 5% (~20 ppt) and 3% (~8 ppt), respectively if biodegradation is not included. The net formation or loss rates are predicted to be reduced by up to 20%. These contributions exceed by far the number concentration of bacteria-containing droplets, which implies that the acids evaporate from bacteria-free droplets and are efficiently taken up and biodegraded in the small portion of droplets. We show that the assumption of an average biodegradation rate in all droplets leads to an overestimate of the biodegradation rate, particularly at pH > 5. Generally, the highest importance of biodegradation is identified for large droplets and at pH ~5, which may be considered representative for remote locations. The results are highly sensitive to the pH value, as it not only increases the partitioning of the acids to the aqueous phase (effective Henry’s law constant) but also the rate constants of the OH reactions which compete with the biodegradation as acid sinks.We conclude that current atmospheric chemistry models may be incomplete to assess the loss of organics in the atmospheric multiphase system as biodegradation might be a significant loss of formic and acetic acids and possibly of related organics.
Exploring the pathways of precipitation, snowmelt and glacier melt through the subsurface in high resolution, coupled, data-driven modeling experiment of the Langshisha catchment in the Himalaya
Authors: Aubry-Wake Caroline , Somers Lauren , Bazilova Varya , Kraaijenbrink Philip , Khanal Sonu , Immerzeel Walter
Published: February 2023

 Groundwater can be an important water source for mountain streams. To gain insights into the sources of groundwater recharge and their pathways to the downstream environments, the interactions between surface water and groundwater are investigated for the Langshisha catchment, in the Langtang basin, Nepal Himalaya. The 0.81 km2 study area ranges in elevation from 4130 to 4450 m. a.s.l., with a landscape of coarse debris, pocket meadows and moraine sediments. It is bordered on three sides by steep mountain cliffs, the Langshisha glacier outlet creek, and the Langtang river.  To simulate the hydrological behaviour of the area, we couple the glacio-hydrological model Spatial Processes in Hydrology (SPHY), a spatially distributed water balance model and the groundwater flow model MODFLOW6. We analyze three approaches to simulate the subsurface hydrology of the area:  (1) using the glacio-hydrological model alone, (2) a one-way coupling of the glacio-hydrological model with a groundwater numerical model, where the groundwater recharge from the glacio-hydrological model is used as input to the groundwater model, and (3) a two-way coupled surface water and groundwater model. The model is evaluated with in-situ field data of soil moisture, shallow groundwater levels and streamflow measurements collected intermittently over the 2013-2022 period as well as isotopic and geochemistry water sample data collected in November 2022.  Preliminary results suggest that despite the additional computational demands and time required to develop and apply a fully coupled approach, it provides essential knowledge regarding the cryosphere-surface water-groundwater interactions. Our preliminary results showcase the importance of field observations to constrain modelling efforts and will serve to guide further model applications to assess the importance of representing cryosphere-surface water-groundwater interactions in mountain landscapes. 
“Cambiare il clima”: theatre and academia meet for a new narrative about climate change
Authors: Vanin Elisa , Manes Costantino , Andorno Marco , Amadio Sebastiano
Published: February 2023

A collaboration between the Department of Environmental, Land and Infrastructure Engineering of Politecnico di Torino and the theatre group Faber Teater resulted in “Cambiare il clima” (Eng: Change the climate, trailer: https://youtu.be/3LTOE3wIoZM): a theatre play taking inspiration from research on climate change monitoring, adaptation and mitigation solutions carried out at Politecnico di Torino, to stimulate reflection on the phenomenon in a wide audience.The wide theme of climate-related consequences for humankind urges to enter into mainstream storytelling. For a long while, the narrative around climate change struggled to find its place in literature, cinema and other arts (see A. Gosh, The Great Derangement). This play attempts to create such a space by telling a story about what science can do about climate change and the importance to intertwine technological progress with economic and political decisions.The main challenge in creating the play was to communicate the exciting world of academic research, without giving up scientific rigor and to highlight the surprising common ground of science and theatre, namely their human, practical and even artisanal dimension. Towards this end, artists had to dive into science and engineering while researchers had to raise their awareness about how their work can stimulate emotions, which are key to deliver important messages to society, such as those related to climate change. The goal was to balance lightness, irony and drama, conveying urgency to the audience, without surrendering to sensationalism.The play was first performed in November 2020 at Politecnico di Torino during Biennale Tecnologia (an important event about technology, in Italy). Since then, it was repeated several times in festivals, events for science communication, schools, etc. It has also received two awards: (1) it was selected among the works published in the Climate ChanCe 2022 creative communication competition organised by Shylock - University Theatre Centre, Venice; (2) one of the videos composing the play won the "Future Earth" award of the Earth Futures Festival, an initiative promoted by UNESCO - International Geoscience Programme and the International Union of Geological Sciences in 2022.The presentation will include:- preferably an oral presentation, summarizing the process that led to the design of the play, the incentives that moved both the researchers and the actors in undertaking this initiative, the challenges they faced and the lessons learnt;- a short video displaying some excerpts from “Cambiare il clima” (with English subtitles), to show the structure of the play, what the researchers’ role was and how they interacted with the actors. Note to the Conveners: since some of the researchers involved in the play – besides the authors - will attend EGU2023, it will be possible also to involve them to listen about their experience, during the presentation or next to the display.
Applying Brillouin thermometry as a novel tool for reconstructing temperatures, depths, and seasonal biases of Holocene/Pleistocene Searles Lake, California
Authors: Olson Kristian , Guillerm Emmanuel , Peaple Mark , Lowenstein Tim , Gardien Véronique , Caupin Frédéric , Feakins Sarah , Tierney Jessica , Stroup Justin , Lund Steve , McGee David
Published: February 2023

Paleoclimate records from lakes of the southwestern USA have been limited by a lack of independent paleothermometers, resulting in conflicting characterizations of millennial-scale variability in temperature and moisture. Here a novel method called Brillouin thermometry is applied to halite-bearing dry intervals of the late Pleistocene/Holocene (45–0 ka) core record of Searles Lake, California. Halite from the sediment-water interface records lake bottom temperatures during dry, high salinity periods. Analysis of modern saline lakes of various chemistries, depths, climate zones, and mixing regimes shows that: 1) average bottom water temperature is approximately equal to mean annual air temperature, and 2) annual range of bottom water temperature is inversely proportional to lake depth. Brillouin temperatures for eight halite intervals 30.6 ka to 8.5 ka range from 11.8 ± 3.6 to 22.4 ± 3.2 °C. Bottom water temperature variability indicates paleolake depths of ~10 m during halite precipitation. Brillouin thermometric results are then assessed in comparison with two additional temperature proxy records from the same Searles Lake sediment core: 1) branched glycerol dialkyl glycerol tetraethers (brGDGTs) extracted from wet mud intervals, and 2) thermodynamic constraints from evaporite minerals and mineral sequences. Temperatures from brGDGTs for mud intervals 44.7 ka to 3.6 ka range from 13.4 ± 2.8 to 23.9 ± 3.0 °C. Comparisons of Brillouin/brGDGT temperatures with predicted equilibrium temperatures of salt crystallization indicate intervals where seasonal temperature variability forced the dissolution and/or recrystallization of existing temperature-sensitive evaporites. The multiproxy temperature record of Searles Lake agrees with other regional records at glacial/interglacial timescales but displays a wider degree of millennial-scale variability, with temperatures during the last glacial ranging from 8.3 °C below modern mean annual temperatures to 3.8 °C above.
Strength performance of high-water content clays stabilized with cement and superabsorbent polymers
Authors: Wang Zhenhua , Rohn Joachim , Xiang Wei
Published: February 2023

An ideal solution for dealing with large volumes of waste clays is to stabilize and use them as fill materials for road construction. This paper presents an experimental study on the strength behavior of the clays with high water content stabilized by cement and superabsorbent polymers (SAP) at different curing periods. The SAP can effectively improve the strength of cement soils, and the increase in strength becomes more significant with time. The microstructures of the stabilized soils are also investigated via mercury intrusion porosimetry (MIP) and microcomputed tomography (Miro-CT). Comparison of the porosity and the pore size distribution of the stabilized soils shows clearly that the SAP facilitated the hydration/pozzolanic reaction through the absorption-release on free water. With this concept, free water, cement content, and curing period are considered as important parameters based on Abrams' law to characterize the strength of the cement-SAP-soil system.
The atmosphere as an inoculator of a functional phyllosphere microbiota
Authors: Mathonat Frédéric , Lehours Anne-Catherine , Vergne Antoine , Ervens Barbara , Amato Pierre
Published: February 2023

The aerial parts of plants constituting the phyllosphere are in constant interaction with the atmosphere and the microorganisms it transports. Some plants have specialized structures that allow them to collect rainwater, the phytotelms. Dipsacus fullonum is a pioneer plant found in the Auvergne region of France that forms water reservoirs around its stem, called phytotelms. Rainfall feeds these reservoirs with water and inoculate them with a particular microbiota, including a high population of anoxygenic phototrophic bacteria (APB), i.e. bacteria capable of utilizing light to generate energy, without fixing carbon dioxide and releasing oxygen. These bacteria often have an impressive capacity to fix atmospheric nitrogen, which is likely beneficial to the plant, which stimulates their development through specialized molecules and structures found inside the phytotelms: glandular hairs. A high concentration of bacteriochlorophyll, a photosynthetic pigment typical of APBs, has been identified by HPLC in reservoir’s water. The pufM gene coding for the small subunit of the photosynthetic reaction centre of APBs was detected by PCR in DNA extracted from phytotelm water, and it was also found prevalent in cloud and rain water samples. Living APB strains were also cultured and isolated from cloud water samples. The prevalence of these bacteria in the atmosphere suggests that anoxygenic photosynthesis could represent a strong selective advantage for survival, and so for long distance microbial dispersion. These bacteria could participate to the fixation of nitrogen in clouds and wet aerosols, and contribute to the biogeochemical cycle of nitrogen by reducing atmospheric N2 into NH3/NH4+ to an unsuspected extent globally.
Irrigation timing retrieval at the plot scale using Surface Soil Moisture derived from Sentinel time series in Europe
Authors: Le Page Michel , Nguyen Thang , Zribi Mehrez , Boone Aaron , Dari Jacopo , Modanesi Sara , Zappa Luca , Ouaadi Nadia , Jarlan Lionel
Published: February 2023

The computation of the water budget of irrigated fields is generally difficult because of unknown irrigation amounts and timing. Automatic detection of irrigation events could greatly simplify the water balance of irrigated fields. The combination of high spatial resolution and high-frequency SAR (Sentinel-1) and optical satellite observations (Sentinel-2) makes the detection of irrigation events potentially feasible. Indeed, optical observation allows following the crop development while SAR observation can provide an estimation of the Surface Soil Moisture (SSM). However, uncertainties due to acquisition configuration or crop geometry and density might affect the retrieval of SSM. Here, an algorithm for irrigation events detection is assessed considering several aspects that could affect SSM retrieval (incidence angle, crop type, crop development) and specific characteristics of irrigation events (irrigation frequency, frequency of observations). Additionally, an alternative soil water budget model, the force-restore approach, is compared with the original bucket soil water budget algorithm. A European dataset of irrigation events collected during the ESA Irrigation+ project (5 sites in France, Germany, and Italy over three years) is used. The performances are analyzed in terms of the F‑score and the seasonal sum of irrigation. Overall, the analysis corroborated that the scores decrease with SSM observation frequency. The impact of the Sentinel-1 configuration (ascending/descending, close to 39°/far from 39°) on the retrieval results is low. The lower scores obtained with small NDVI compared to large NDVI were almost systematic, which is counter-intuitive, but might have been due to the larger number of irrigation events during high vegetation periods. The scores decreased as irrigation frequency increased, which was substantiated by the fact that the scores were better in France (more sprinkler irrigation) than in Germany (more localized irrigation). The strategy of merging different runs versus the strategy of interpolating all SSM data for one run has produced comparable results. The estimated cumulative sum of irrigation was around -20% lower compared to the reference dataset in the best cases. Finally, the replacement of the original SSM model by the Force-restore provided an improvement of about 6% on the F‑score, and also narrowed the error on cumulative seasonal irrigation. This study opens new perspectives for the advancement of irrigation retrieval at large scale based on SSM data sets through an in-depth analysis of results as a function of satellite configuration, irrigation techniques, and crops.
Topographic controls on the distribution of dark ice on the surface of the Greenland Ice Sheet
Authors: Feng Shunan , Cook Joseph Mitchell , Anesio Alexandre Magno , Benning Liane G. , Tranter Martyn
Published: February 2023

The Greenland Ice Sheet (GrIS) is the largest single cyospheric contributor to global sea level rise. The surface ice albedo modulates the absorption of solar radiation and the current darkening of the GrIS enhances the surface meltwater production. However, the dark ice is unevenly distributed on the GrIS. Remote sensing observations found that dark ice is limited to the margin in the southeast region, while the spatial extent of dark ice stretches further inland in the southwest GrIS. This band of dark ice, with an albedo that is significantly lower than the surrounding ice in the melt season, is known as the Dark Zone. One hypothesis is that the spatial distribution of dark ice is influenced by topography, and surface slope in particular. This study attempts to verify this hypothesis and presents the first medium resolution (30 m) analysis of the topographic controls on the distribution of dark ice on the surface of the GrIS. The association between albedo and topographic factors, such as elevation, slope and aspect, and the distance from the ice margin, and the duration of bare ice exposure, are investigated using the ArcticDEM and a satellite albedo product derived from a harmonized Landsat and Sentinel 2 dataset. The results may allow certain controls on glacier ice algal growth, a key contributor to the progressive darkening of the ice surface, to be surmised.
Uniquely low stable iron isotopic signatures in deep marine sediments caused by Rayleigh distillation
Authors: Köster Male , Staubwasser Michael , Meixner Anette , Kasemann Simone A. , Manners Hayley R. , Morono Yuki , Inagaki Fumio , Heuer Verena B. , Kasten Sabine , Henkel Susann
Published: February 2023

Microbially mediated iron (Fe) reduction is suggested to be one of the earliest metabolic pathways on Earth and Fe(III)-reducing microorganisms might be key inhabitants of the deep and hot biosphere [1, 2]. Since microbial Fe cycling is typically accompanied by Fe isotope fractionation, stable Fe isotopes (δ56Fe) are used as tracer for microbial processes in modern and ancient marine sediments [3, 4]. Here we present Fe isotope data for dissolved and sequentially extracted sedimentary Fe pools from subseafloor sediments that were recovered during International Ocean Discovery Program Expedition 370 from a 1,180 m deep hole drilled in the Nankai Trough off Japan where temperatures of up to 120°C are reached at the sediment-basement interface. The expedition aimed at exploring the temperature limit of microbial life and identifying geochemical and microbial signatures that differentiate the biotic and abiotic realms [5, 6]. Dissolved Fe (Fe(II)aq) is isotopically light throughout the ferruginous sediment interval but some samples have exceptionally light δ56Fe values. Such light δ56Fe values have never been reported in natural marine environments and cannot be solely attributed to microbially mediated Fe(III) reduction. We show that the light δ56Fe values are best explained by a Rayleigh distillation model where Fe(II)aq is continuously removed from the pore water by diffusion and adsorption onto Fe (oxyhydr)oxide surfaces. While the microbially mediated Fe(II)aq release has ceased due to an increase in temperature beyond the threshold of mesophilic microorganisms, the abiotic diffusional and adsorptive Fe(II)aq removal continued, leading to uniquely light δ56Fe values. These findings have important implications for the interpretation of Fe isotope records especially in deep subseafloor sediments. References:[1] Vargas, M. et al., 1998. Nature 395: 65-67.[2] Kashefi, K. and Lovley, D.R., 2003. Science 301: 934-934.[3] Beard, B.L. et al., 1999. Science 285: 1889-1892.[4] Anbar, A.D. and Rouxel, O., 2007. Annu. Rev. Earth Planet. Sci. 35: 717-746.[5] Heuer, V.B. et al., 2017. In Proc. IODP Volume 370.[6] Heuer, V.B. et al., 2020. Science 370: 1230-1234.
About the use of Satellite Hyperspectral Images for Methane Detection
Authors: Masin Fabrizio , Maestri Tiziano , Martinazzo Michele
Published: February 2023

As global warming continues to be one of the greatest threats to Earth environment, the detection and monitoring of natural and anthropogenic emissions of greenhouse gases holds a critical role as the first step of any danger reduction policy. New generation spaceborne hyperspectral instruments cover large portions of the Earth while maintaining a high enough spectral and spatial resolution to investigate the contribution of single molecular species and accurately localize their emission source. The Matched Filter method is used to search enhanced concentrations of methane in the atmospheric column. PRISMA, ASI’s newest hyperspectral sensor, data are analysed. Both strong and weak CH4 emissions, in multiple scenarios, are investigated. It is demonstrated that PRISMA data allow also the identification of methane non-punctual sources when the land gas emission is very high. An estimated flux in the order of 4000 kg/h is found for a case study considering a landfill in India.
Drought monitoring over the Kruger National Park (2000-2020) integrating remote sensing data.
Authors: Dube Timothy , Ramoelo Abel , Shoko Cletah , Dominic Mazvimavi , Gonzalez-Dugo Maria P. , Nieto Hector , Andreu Ana
Published: February 2023

Semiarid regions shaped as a mosaic of savanna-type rangelands, croplands, and other uses such as livelihoods, or natural reserves, cover large areas in Southern Africa. They constitute an essential example of multiple uses of natural resources, combining a high environmental value with great importance in the rural economy and development. These systems are water-limited and highly sensitive to changes in climate, environmental conditions, and land management practices. Although the vegetation of these areas is adapted to variable climatic conditions and dry periods, the increase in drought intensity, duration, and frequency precipitate their degradation.  In Southern Africa, recurrent droughts have strained rainfed agriculture and pasture production, decimating livestock and wildlife. During 2015 and 2016, South African savannas were subjected to a severe drought associated with a strong El Niño event. Open-source satellite time series provide vital information to assess water availability and long-term drought, to help design early warning and conservation strategies.  In this work, we applied the TSEB (Two Source Energy Balance) model integrating MODIS-derived products (1 km) from 2000 to 2021 over the Kruger National Park (KNP) in South Africa. The model was previously validated over the Skukuza experimental site with good agreement. ET followed precipitation rates, although some years with low precipitation maintained average ET values. This may be caused by the ability of the trees to reach groundwater (deep fractured aquifers and alluvial aquifers can be found in the KNP). During some years (e.g., 2004, 2009), annual total ET was much higher than mean annual values. This may be caused by an extreme annual evaporative atmospheric demand and relatively high precipitation. The anomalies of the ratio of ET to reference ET were used as an indicator of agricultural drought on annual scales, and 2002/2003, 2007/2008 and 2015/2016 years stood out for their negative values. The approach helped to model drought over Kruger Park in the long term, providing an insight into the characteristics of the events.Acknowledgment: This work has been carried out through the project "DroughT impACt on the vegeTation of South African semIarid mosaiC landscapes: Implications on grass-crop-lands primary production" funded by the European Space Agency in the framework of the "EO AFRICA R&D Facility".