bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of enhanced mineral weathering on soil structure and organic carbon storage
Authors: Pihlap Evelin , Olagaray Noemma , Klöffel Tobias , Masters Michael D. , Kantola Ilsa B. , Beerling David J. , Planavsky Noah J.
Published: March 2024

Enhanced mineral weathering is a nature-based solution to reduce atmospheric and soil CO2 concentrations in agricultural settings. Spreading finely grained basalt on the soil leads to subsequent chemical reactions that alters soil properties by changing soil pH, nutrient availability and particle-size distribution. Changes in these soil properties activate soil feedback mechanisms such as shifts in soil biogeochemical reactions or plant growth dynamics. Several studies have examined changes in pH and CEC after basalt application; however, basalt application may have an additional influence on the soil’s structural quality and the quantity of soil organic carbon (OC). In this study, we used a long-term field trial of basalt application at the University of Illinois Energy Farm (Illinois, USA) to elucidate changes in soil structure and OC storage. The field study was launched in 2016 using a randomized block design consisting of control (n=4, no basalt application), basalt (n=4), and lime (n=3) treatments. The sampling campaign was conducted in 2022 and in each field, we sampled with stainless steel cylinders (250 cm3) at depths of 1—6 cm and 15—20 cm. All samples were analyzed for nutrient content, OC concentration, pH, CEC and select samples were analyzed for soil water characteristic curves and aggregate-size distribution.Basalt and lime application had a significant effect on soil pH, Ca concentration and the dominance of Ca2+ as an exchangeable cation, all which reflect evidence of increased soil structural quality. Indeed, soil structure, as quantified from the soil water characteristic curves using the concept of relative entropy (the Kullback-Leibler divergence), showed clear signs of enhancement after lime application. However, this was less evident for the basalt treatment. Despite improvements in soil structure, there were no effects on OC storage in either of the treatments. Aggregate characterization for OC concentration showed that the depth stratification had a greater role in carbon protection than the soil treatment itself, where the highest OC enrichment (EOC>1) was observed at the lower sampling depth of 15—20 cm. The organo-mineral association in the finest fraction was not affected by the treatment because neither the aggregate size class distribution nor OC accumulation in the finest fraction differed among the control, lime, and basalt treatments. Enhanced mineral weathering improves soil nutrient content, pH, and, potentially, soil structure; however, these changes do not directly result in higher OC storage, which underlines the complex nature of OC dynamics.
Reassessing Paleocene CO2 and Carbon Cycling using Process-Informed Joint Proxy Inversion
Authors: Bowen Gabriel , Harper Dustin , Da Jiawei , Kelson Julia
Published: March 2024

The Paleocene Epoch represents a transitional Earth system state featuring climatic relaxation between the extreme warmth of the Late Cretaceous and Early Eocene. Carbon isotope and sedimentological data have been invoked as evidence for elevated organic carbon burial and CO2 drawdown throughout the early Paleocene, constituting a potential driver of and/or feedback on climate change. Despite this, quantitative proxy reconstructions of Paleocene atmospheric CO2 concentrations have remained sparse, limiting our ability to test hypotheses for the role of carbon cycle change in Paleocene Earth system change.Here we produce quantitative CO2 reconstructions spanning the Paleocene by combining data from marine (foraminiferal calcite) and terrestrial (pedogenic carbonate) proxy systems. We integrate data from these proxy systems, together with complementary paleo-environmental proxy data, using newly developed proxy system models implemented within the Bayesian Joint Proxy Inversion (JPI) framework. Although each individual proxy system is under-constrained, the combination of information from distinct systems and constraints provided by ancillary data produces a coherent, well-resolved paleo-CO2 reconstruction. The record suggests strong coupling between carbon cycle processes, atmospheric CO2 levels, and climate throughout the Paleocene. Integration of a simple carbon cycle model driven by changing sedimentary organic carbon burial within the JPI analysis provides additional constraints on the CO2 reconstruction and demonstrates that this process is generally consistent with the available proxy evidence.
Retaining Detail In Cenozoic CO2 Curves
Authors: Whiteford Ross , Rae James , Heaton Timothy
Published: March 2024

Palaeo CO2 concentration data has very variable density across the Cenozoic. Some events (such as the PETM) and intervals (such as glacial-interglacial cycles) are covered by high resolution datasets, whereas at other times the spacing between datapoints is much greater. Because of this variable data density, combining the datapoints into a line describing the evolution of palaeo CO2 usually focusses on either a short interval or on the long term trend (by blurring short term detail). We present a new approach which uses basis splines to produce a Cenozoic CO2 curve. The spline approach allows us to produce a curve which retains details in times where we have the requisite data density without introducing problematic artefacts at times with lower data density. The spline method makes it possible for the first time to produce a single curve which is sensible regardless of the timespan of interest.
Adaptation to climate change: Regional sea surface temperature scenarios for the North Sea and the Baltic Sea
Authors: Ehlers Birte-Marie , Su Jian , Janssen Frank
Published: March 2024

The German Strategy for Adaptation to Climate Change (Deutsche Anpassungsstrategie - DAS) is the political framework to climate change adaptation in Germany and laid the foundation to prepare for the impacts of climate change and reduce climate risks in a continuous process. The DAS core service “Climate and Water” provides monitoring and projection data to evaluate requirements for climate change adaptation.An ensemble of regional climate ocean simulations is provided to tackle a large number of questions on the topics of sea level, water temperature, salinity and currents. The regional climate ocean simulation ensemble is based on atmospheric forcing from five members of the EURO-CORDEX ensemble. The simulations were calculated for a thirty-year ”historical” period (1971-2000), a thirty-year ”near future” period (2031-2060) and one for the ”far future” (2071-2100) for the RCP8.5 scenario.In this study, we focus on the evaluation of the sea surface temperature (SST), which has a major impact on the ecosystem and therefore must be part of the adaptation strategy. A comparison of all SST model results with observational data provides a bias correction of the individual ensemble members, which than is also applied to the projected data. The ensemble approach is examined with respect to substantial uncertainties and different types of ensemble representation are discussed. The results are prepared for policymakers and practitioners engaged in coastal risk assessment and adaptation planning and will be available on the internet at https://das.bsh.de.
Spatial fluctuations of the Arctic sea ice border
Authors: Hummel Clara
Published: March 2024

Every year, the area of the Arctic sea-ice decreases in the boreal spring and summer and reaches its yearly minimum in the early autumn. Due to global warming, Arctic summer sea ice will most probably disappear. As the sea ice cover decreases, its border is retreating northwards towards the central Arctic. This retreat is not uniform in space and the variability of the border’s movement further North could yield an early warning signal for summer sea ice loss. Here, we track the sea ice border from time series obtained from models of various complexity and observations to study the spatial variability of the border’s movement as Arctic summer sea ice approaches its disappearance.
Coupled simulation of phreatic groundwater and surface fluxes from the terrestrial biosphere in Belgium
Authors: De Pue Jan , Munier Simon , Barrios José Miguel , Arboleda Alirio , Baguis Pierre , Hamdi Rafiq , Meulenberghs Françoise
Published: March 2024

Phreatic groundwater hydrology has a well-documented influence on the land water/energy/carbon cycles. To capture the resilience of the biosphere to dry spells in land surface models, it is particularly crucial to incorporate groundwater dynamics. With the ISBA-CTRIP land surface system, it is possible to perform a coupled simulation of the land surface fluxes and groundwater hydrology. Here, we evaluate this model configuration over Belgium, and focus on the quality of the simulated groundwater dynamics, soil moisture and resulting surface fluxes. A network of piezometer and eddy covariance towers is used to validate the model outcomes. Furthermore, the sensitivity of the model parametrization is analyzed (considering different pedotransfer functions), and the impact of groundwater coupling on the surface fluxes is quantified.
Palaeoenvironmental changes and human-environment interactions in the surroundings of La Silla del Papa, SW Spain
Authors: Brill Dominik , May Simon Matthias , Norpoth Maike , Pint Anna , Shumilovskikh Lyudmila , Raith Kira , Rixhon Gilles , Moret Pierre , Jiménez-Vialás Helena , Grau-Mira Ignasi , García-Jiménez Iván , Marzoli Dirce , León-Martín César , Reicherter Klaus , Brückner Helmut
Published: March 2024

The surroundings of the Strait of Gibraltar in southern Iberia are well known as a crossroads for population movements, cultural exchange and trade from Late Prehistory to Modern Times. However, questions remain about how this historical development has impacted the environment. The settlement of La Silla del Papa, an important hillfort located in the Sierra de la Plata in southern Andalusia (Cádiz), and its territory represent an ideal location for long-term studies of human-environment interactions. It was occupied throughout the entire Iron Age, replaced by the coastal town of Baelo Claudia during Roman times, and reoccupied in the early Middle Ages. Therefore, the geoarchaeological investigations in the surroundings of La Silla del Papa within the framework of the interdisciplinary project “Archeostraits” aimed at constraining the ecological conditions and human-environment interactions during the Mid- and Late Holocene and during the most important human occupation phases. Our investigations included sedimentological, geochemical, chronological (OSL, 14C-AMS, diagnostic pottery), microfaunal and palynological analyses of nine sediment profiles as well as nine vibracores from the catchment of the Río del Cachón, a small river originating in the Sierra de la Plata, just below La Silla del Papa. Our results document an early Mid-Holocene open marine embayment in what is now the lower floodplain, which rapidly transformed into a coastal lagoon and later into freshwater-dominated wetlands. After ~2100 BP, fluvial and alluvial deposition considerably increased, suggesting high anthropogenic impact on the local landscape during the Roman or post-Roman times. Palynological results reveal fluctuating agricultural and pastoral activities and suggest two distinct periods of landscape opening between 7000-6000 BP and during the Phoenician and Iron Age period.
Wheat irrigation in Marrakech conditions: A Simulation Study using SALTMED
Authors: El Moussaoui El Houcine , Moumni Aicha , Khabba Said , Lahrouni Abderrahman
Published: March 2024

In Morocco, agriculture accounts for 80-90% of water resources. Available data show that the performance of current irrigation systems remains low to medium, with water losses at plots ranging from 30 to 40%, divided between percolation and evaporation. Gravity irrigation is almost total in the study area, resulting in significant percolation losses. In principle, this percolation contributes mainly to the recharge of the aquifer.The purpose of this study was to evaluate, by simulation, the impact of irrigation techniques on wheat yield and growth using the generic agro-environmental model SALTMED under the climatic and soil conditions of zone R3, which is an irrigation area located in the region of Sidi Rahal about 40 km east of the city of Marrakech in the plain of Haouz. We started the study by calibrating the model based on two parameters: photosynthetic efficiency and harvest index. After calibration, we compared different irrigation techniques implemented in the model (surface irrigation, sprinkler irrigation, and drip irrigation). Simulation results showed that the drip irrigation technique is the most economical, exhibiting the lowest losses attributed to percolation and soil evaporation. Notably, percolation, a significant contributor to groundwater recharge, measured approximately 255.5 mm/season. In addition, the irrigation practice in the study area appears to be overestimated during the observed season and could be reduced by half, according to SALTMED. When the irrigation dose is halved, the simulated yield (grain and total biomass) decreases by only 1.33%.
Inversion-based Time Series Analysis of PS-InSAR Data: Uncovering the Origins of Subsidence and Annual Fluctuations in Southern Hesse, Germany
Authors: Rudolf Michael , Krzepek Katrin , Homuth Benjamin , Iwaszczuk Dorota , Henk Andreas
Published: March 2024

The uplift and subsidence of the earth's surface can be attributed to many different processes. In urban regions in particular, it is important to understand which ground movements occur, whether they pose a risk to infrastructure and whether countermeasures can be taken. While events such as earthquakes, sinkholes and landslides have abrupt and visible effects, slow ground movements such as slope instabilities and tectonic movements are difficult to detect and it can take decades for visible damage to occur. Remote sensing, especially InSAR and Persistent Scatterer InSAR, provides high spatial and temporal coverage for monitoring these processes. The state of Hesse in central Germany is confronted with various ground movements, including former open-cast lignite mines, active salt mining and landslide-prone geological units. Our study aims to explore previously unknown ground movements in urban regions using remote sensing, analyse detected areas, determine causes, assess risks and anticipate future developments. We use Persistent Scatterer Interferometry (PS-InSAR) data from the Ground Motion Service Germany (BBD) to analyse ground motion patterns. With the help of a Ground Motion Analyser (GMA), time series analysis and external data, we identify regions with significant ground movements throughout the federal state. A case study in Frankfurt am Main, located on the northern edge of the Upper Rhine Graben, shows subsidence that was probably caused by groundwater extraction during the construction of buildings. Another case study in Crumstadt, in the centre of the northern Upper Rhine Graben, shows pronounced seasonal fluctuations, possibly related to temperature and activity in an underground gas reservoir. In both cases, an analysis of external data such as groundwater levels, climate data, construction activity, mining activities, hydrogeological and geological conditions must be taken into account. The ground movements caused by the various possible causes can sometimes be very similar, so a solid external database is particularly important. With the help of the results, the ground movements measured by remote sensing can be linked both qualitatively and quantitatively with the regional conditions. Our results thus contribute to understanding and mitigating the effects of ground movements and underline the importance of analysing both time-varying movements and linear velocities in parallel with external data.
Static and Quasi-Static Inversion of Fault Slip During Laboratory Earthquakes
Authors: Arzu Feyza , Twardzik Cedric , Fryer Barnaby , Ampuero Jean-Paul , Passelègue François
Published: March 2024

Inferring from seismological data the spatio-temporal distribution of slip during earthquakes remains a challenge due to the large size, non-uniqueness and ill-posedness of the inverse problem. Consequently, finite source inversion usually relies on simplifying assumptions. Moreover, in the absence of ground truth source data, the evaluation of the performance of source inversion is only possible through synthetic tests.To address these concerns and test the viability of the inversion methods used for natural earthquakes, laboratory earthquakes offer a valuable alternative. They enable us to work with "simulated real data" and provide a relatively well-constrained solution. Here, we employ a biaxial apparatus capable of reproducing shear rupture along a rectangular fault separating two PMMA blocks. Both normal and shear stresses are initially increased up to the target normal stress using external pressure pumps, assuming a fixed shear to normal stress ratio of 0.3. Subsequently, the shear stress is increased until instabilities occur at a peak friction of 0.4. During each seismic rupture, we measure the acceleration at 20 receivers along the fault. The acceleration data are integrated twice into displacements, and then used to invert for the slip history, which is compared to direct measurements using laser sensors placed through the fault. For a static inversion of final slip, predictions are computed using Okada's formulation and the posterior probability density function of the slip history is obtained using a Metropolis algorithm. We will also report on results of quasi-static inversion. The adoption of a probabilistic approach provided a range of solutions, essential for assessing the uncertainty in our results and addressing the issue of non-uniqueness. Ultimately, the obtained results will offer insights into inversion methods, presenting their strengths and limitations more realistically than when using artificially generated synthetic datasets.
The localized rotations in Junggar Block for the last 50 Myr: new paleomagnetic constraints 
Authors: Zhong Mengting , Kravchinsky Vadim , Zhang Rui , Cheng Xin
Published: March 2024

We present an analysis of paleomagnetic data from Cenozoic sedimentary rocks of the northern Junggar Block in central Asia to assess if the northern Junggar Block has suffered vertical axis rotations with respect to stable Eurasia. Stepwise thermal demagnetizations isolated a stable high-temperature component of magnetization in most specimens, which we interpret as the primary magnetization from the positive reversal test. Based on high-resolution magnetostratigraphic studies (Zhang et al., 2007, 2012), we calculated the mean direction of each 5 Myrs of 44-30 Ma and 25-17 Ma covered by the sample age and yielded seven mean directions in 45-37.5 Ma, 40-35 Ma, 37.5-32.5 Ma, 35-30 Ma, 25-20 Ma, 22.5-17.5 Ma, respectively. The variation between the observed declination from the study area and the reference declination from Eurasia indicates that a local counterclockwise rotation of 18.8 ± 11.4° took place during 40±2.5 - 35±2.5 Ma. Together with the paleomagnetic data during 23-3.1 Ma in the southern part of the Junggar Basin (Charreau et al., 2005, 2009), it can be concluded that Junggar Block experienced local counterclockwise rotation with respect to the Eurasia in the piedmont of the north and south rim successively due to the strike-slip fault. At a larger scale, the blocks in the Central Asia Right–Slip Fault Zone have experienced tectonic rotation at different times under the far-field effect of India-Eurasia collision, that is, formed an overall counterclockwise vertical axis rotation mode of different stages because of strike-slip faulting.
Rare earth element dynamics in the deep subsurface of a high energy beach in the North Sea
Authors: Roberts Magali , Reckhardt Anja , Abarike Grace , Amoako Kojo , Meyer Rena , Massmann Gudrun , Pahnke Katharina
Published: March 2024

Subterranean estuaries (STE) of high energy beaches are important coastal reactors that can alter elemental fluxes to the sea. The advective flow of pore water in these STE systems has rapid transport rates due to the high permeability of medium to coarse grained sediments. This flow is controlled by the inland hydraulic gradient, density differences caused by different matrixes (fresh and saline), and oceanic forces (tides and waves). Rare earth elements (REEs) are useful tracers for biogeochemical processes like scavenging, redox changes and provenance. Therefore, a better understanding of their dynamics in different environments is required. In order to investigate REE cycling in the deep subsurface of a sandy beach on spatial and temporal scales, groundwater REE concentrations were analysed along a cross-shore transect down to a depth of 24 m below the sediment surface over the timespan of a year. Together with other trace element, nutrient, and dissolved organic carbon concentrations as well as environmental data (salinity, temperature, pH) from the same stations and depths, the results provide first insight into spatio-temporal variations of biogeochemical processes and changes that lead to the retention or mobilisation of REEs in the deep STE of a high-energy beach. 
Reconstructing GRACE-like TWSA maps from 1992 on by combining data-driven methods with time-variable gravity fields from SLR range analyses
Authors: Hacker Charlotte , Kusche Jürgen , Löcher Anno , Li Fupeng
Published: March 2024

The Gravity Recovery And Climate Experiment (GRACE) and its follow-on mission, GRACE-FO, have observed global mass changes and transports, expressed as total water storage anomalies (TWSA), for over two decades. However, for climate change attribution and other applications, multi-decadal TWSA time series are required. This need has triggered several studies on reconstructing TWSA via regression approaches or machine learning techniques, with the help of predictor variables such as rainfall or sea surface temperature. Here, we combine such an approach, for the first time, with low-resolution information from geodetic satellite laser ranging (SLR). The reconstruction is formulated on a GRACE-derived empirical orthogonal functions (EOFs) basis and complemented with the Löcher and Kusche (2021) approach, in which global gravity fields are solved from SLR ranges in a GRACE EOF basis for the pre-GRACE time frame. Although our technique works globally, we focus mainly on European basins and reconstruct water storage anomalies from 1992 onward.
Mapping basalt lava flows at Dive Ghat (Pune, India) using multichannel analysis of surface wave (MASW) technique
Authors: Rashi Rashi , Dehiya Rahul , Sarkar Sudipta , Duraiswami Raymond
Published: March 2024

Lava-flow structure and morphology provide insights into eruption styles, emplacement mechanisms, and post-emplacement alterations like weathering. However, the challenge lies in quantifying subsurface structures of buried lava flows beneath soil and vegetation cover. We present a case study of lave flow mapping employing seismic methods from the Dive Ghat region of Pune, situated in the Deccan Volcanic Province. Seismic data was collected using a 48-channel engineering seismograph with 1m receiver spacing and 2m shot spacing via a sledgehammer source. The seismic profile is taken parallel (roughly 4 m away) to the approximately 10 m vertical exposed section, which is used for cross-validation of the flow geometry, and it shows the presence of roughly six inches of red bole layer overlaying on a highly weathered basalt. The observed data is analyzed through refraction and multichannel analysis of surface wave (MASW) techniques. The refraction method yielded a high-resolution P-wave velocity model in the near subsurface with P-wave velocity (Vp) ranging from 0.3–4.5 km/s. However, the refraction method fails to image highly weathered basalt, which is expected as no critically refracted wave will be generated from the top of a low-velocity layer. The MASW method delivered a horizontally smeared S-wave velocity model where S-wave velocity (Vs) varies from 0.15–2.2 km/s. The subsurface S-wave model has a low-velocity layer of around 0.7 km/s Vs velocity embedded between 8.5–14m, which correlates to a red bole layer and underlying fractured basalt formed through weathering. Furthermore, a Vp-Vs cross plot is calculated to characterize different seismic units in velocity sections. The results obtained in this study may serve as an analogue to map near-surface flow geometry in unexposed sections in the Deccan Volcanic Province region. The MASW method successfully imaged the buried red bole layer and underlying weathered zone, which is crucial for agriculture due to its organic content. The imaging also holds implications for slope stability studies, emphasizing the importance of seismic characterization for hazard zonation, especially concerning the red bole and fractured basalt.
The influence of ice thermodynamic characteristics on the lake-atmosphere interaction process over a large high-altitude dimictic lake, Nam Co
Authors: Shi Xingdong , Wang Binbin , Ma Yaoming , Sun Lijun
Published: March 2024

The lakes’ frozen and melting process is largely determined by the ice thermodynamic characteristics, i.e. the momentum roughness length, the surface albedo etc, which can impact on the lake-atmosphere interaction process, and finally affect the local hydrological cycle and the water resources. However, because of the data scarcity during frozen period of the lakes, there are relatively few studies and less clarity on the lakes’ thermodynamic characteristics, especially over the harsh environment of the Tibetan Plateau. In this study, based on meteorological forcing, eddy covariance measurements and remote sensing products, we explored,the effects of ice surface momentum roughness length (z0m) and snowfall on ice-frozen processes in Nam Co by using WRF-Lake model. The simulation results show that the WRF-Lake model can reproduce the mixing and stratification pattern, but with an over-early ice break up date and an overestimated sublimation. Based on eddy covariance measurements, the typical z0m value of ice surface  Nam Co is approximately one magnitude lower than the default value in WRF-Lake (3.04×10-4 m vs 1×10-3 m), Numerical simulations indicate that the decrease of the ice surface will contribute to a warmer lake surface, an increase of the sensible heat flux, a decrease of the sublimation and a shorten ice-covered duration. Moreover, snowfall events can cool the lake significantly, then delay the lake ice break up date and reduce the sublimation significantly. After considering the two factors the WRF-Lake model can improve the simulated over-early ice break up date and the overestimated sublimation significantly. Therefore, this study provides valuable in situ measurements of the ice-atmosphere interaction process and shows significance for quantifying lake’ water resouces and climate effects.Keywords: ice phenology, roughness length, lake-atmosphere interaction
Neural network-based hydrology corrections for borehole strainmeters
Authors: Hawthorne Jessica
Published: March 2024

Borehole strainmeters are remarkably precise instruments.  They are often installed to record deformation produced by earthquakes, postseismic slip, and slow earthquakes.  Strainmeters can record such tectonic deformation on timescales of minutes to months with a precision of 0.1 to 1 nanostrain; they record sub-Angstrom changes in borehole width.  However, the instruments’ high precision also extends to non-tectonic signals.  The borehole width often changes by more than 1 Angstrom when it rains, when atmospheric pressure increases, and when snow loads the ground.  Thus if we want to take full advantage of the instruments and investigate tectonic deformation with high precision, we need to understand and remove the deformation produced by non-tectonic signals like water loading.So in this study, I present several neural network-based models of hydrologic deformation.  Neural networks are ideal for this modelling as they can accommodate the nonlinearity of the system; 1 cm of rain will cause different deformation if it falls on saturated, winter soil than if it falls on dry, summer soil.  Further, neural networks can take advantage of the abundance of local weather data, including at short timescales.  In my initial modelling, I attempt to reproduce and predict strain as a function of current and past precipitation, atmospheric pressure, wind speed, and temperature.  For simplicity and ease of use, all these parameters are taken from the ECMWF reanalysis models.I design two neural networks to model the observed strain, using physical intuition to limit the number of free parameters and thus improve the training.  The first network is simple; it creates 10 linear combinations of past rainfall, with exclusively positive weights, and then combines those linear combinations to predict the strain.  The second network also creates 10 linear combinations of past rainfall with positive weights.  But it multiplies those linear combinations of rain by nonlinear functions that could represent the state of the Earth and aquifers.  These nonlinear functions include dependencies on past rainfall, atmospheric pressure, wind speed, and temperature.These networks train quickly, within a few minutes, and they do a reasonable job of producing the first-order features of the strain.  Both models accommodate more than 50% of the hydrologic signal on timescales of days.  Such modelling may or may not be interesting to hydrologists, but for those interested in tectonic deformation, reproducing and removing 50% of the hydrologic signal means removing 50% of the noise.It is likely that a better developed and regularised model could remove much more of the noise, and we are continuing to add constraints, initial weights, and training schemes to improve the hydrologic modelling.
One-year eddy covariance CO2 fluxes at short and tall towers in the Paris area
Authors: Bignotti Laura , Depuydt Jérémie , Herig Coimbra Pedro , Stella Patrick , Buysse Pauline , Kalalian Carmen , Nief Guillaume , Ramonet Michel , Loubet Benjamin
Published: March 2024

Nowadays, around 50% of the global population lives in cities and this percentage is expected to increase to 70% by 2050 (UN-Habitat, Word City Report 2022). As a result, cities have become a major source of greenhouse gases, and were estimated to account for over 70% of global GHG energy-related emissions (IEA, 2008). A correct quantification of these emissions is crucial for developing climate action plans and monitoring their effectiveness. To this purpose, the PAUL project was designed to develop systematic observations of GHG fluxes in three pilot cities of different size: Zurich, Paris and Munich.In this framework, eddy covariance measurements of CO2 fluxes were started in February 2023 at two urban sites in the Paris area and are currently running to capture the seasonal and spatial variation of fluxes along a gradient of urbanisation. The two sites: a short tower on the rooftop of a university building in the city centre of Paris (Jussieu) and a tall tower (~100 m) on the NE periphery of the city (Romainville) are characterised by a different land cover composition within their footprint: in Jussieu, the smaller footprint spans a densely urbanised area, while in Romainville the wider footprint covers a less densely urbanised area with some vegetated patches.Overall, one-year measurements confirmed the city was a source of CO2, as both sites showed a net positive CO2 flux. However, daily flux patterns were different: While in the city centre (Jussieu) the CO2 emission was highest during the diurnal hours [ FCO2 ~ 5 µmol m-2 s-1] and close to zero during the night, on the contrary, in the periphery (Romainville) positive fluxes with highest intensity were observed during the night [ FCO2 ~ 5 – 7 µmol m-2 s-1], while a decrease of CO2 emission were measured in the middle of the day. Romainville was indeed closer to the diurnal net CO2 flux patterns observed at the ICOS ecosystem sites in the south and west of Paris (FR-FON forest, FR-GRI crop).People’s habits were found to play an important role on the observed fluxes in Jussieu as distinct daily patterns were seen between weekdays and weekends. This was not the case for Romainville where uniform daily flux cycles were observed along the week. Visible seasonal differences in the monthly diurnal patterns evidenced the influence of multiple anthropogenic and biogenic drivers which played a key role in different periods of the year and the day. 
Rossby wave packets driving concurrent and non-concurrent heatwaves in the Northern and Southern Hemisphere mid-latitudes
Authors: Pyrina Maria , Wicker Wolfgang , de Vries Andries Jan , Fragkoulidis Georgios , Domeisen Daniela I.V.
Published: March 2024

Heatwaves that occur simultaneously over several regions, termed concurrent heatwaves, pose compounding threats to society and the environment. Amplified quasi-stationary circumglobal Rossby wave patterns (CGWPs) and high-amplitude transient non-circumglobal Rossby Wave Packets (RWPs) have been proposed as two possible explanations for the occurrence of heatwaves. The relation of these mechanisms for heatwaves has been investigated over different timescales, but their relevance for concurrent and non-concurrent heatwaves remains unexplored. In the present study we focus on daily time scales and investigate the relevance of the global CGWP amplitude and of the local RWP amplitude for the occurrence of concurrent and non-concurrent heatwaves over the Northern Hemisphere (NH) and Southern Hemisphere (SH) mid-latitudes. To distinguish between concurrent and non-concurrent heatwaves we apply a k-means clustering algorithm on all heatwaves detected in ERA5 reanalysis data within the 1959–2021 period. We identify 42 spatial clusters of heatwaves in the NH and 53 in the SH. In all identified clusters, mid-latitude heatwaves typically occur at the leading edge of RWPs where Rossby wave breaking takes place in the form of ridge building or block formation. No specific zonal wavenumber is more frequently related to the concurrent or to the non-concurrent heatwave category. However, for high global CGWP amplitudes concurrent heatwaves occur more often in the NH when the dominant zonal wavenumber is k = 7, and non-concurrent heatwaves occur more often in the SH for k = 5. The mid-latitude regions exhibiting increased heatwave probabilities under the influence of either global or local high wave amplitude, include western North America, central Europe, Black Sea, Tibet, the southwest coast of Australia, as well as the southern Indian and Atlantic Oceans. Over those regions, the local high amplitude RWPs increase heatwave probabilities by a factor ranging from 4 to 7, whereas the maximum factor for high global CGWP amplitude is 2. These results emphasize the importance of the daily RWP amplitude and the weak association of the global CGWP amplitude to heatwave occurrence over the NH and SH mid-latitudes. This research for the first time investigates the underlying atmospheric dynamical processes that contribute to the development of concurrent and non-concurrent heat extremes, a crucial step towards improving our understanding and ability to predict heatwave variability at weather and longer time scales.
PSInet – a global water potential network to improve understanding of ecosystems water status and flows
Authors: Novick Kim , Guo Jessica
Published: March 2024

Anticipating and preparing for life on a warming planet requires a predictive understanding of how increasing drought and heat stress will affect terrestrial plants and the many services they provide. The water potential of soils and plants – which can be imagined as the blood pressure of the natural world – is a fundamental driver of ecosystem water flows, and directly controls many aspects of plant functioning during drought. However, and especially when compared to the rich information contained in flux tower networks like AmeriFlux and FLUXNET, observations of water potential are relatively sparse, undiscoverable, and plagued by methodological disparities that constrain the synthetic research necessary to improve conceptual understanding and predictive models of plant drought responses. A new network – PSInet – will confront this water potential information gap by creating an open and accessible global water potential database that is harmonized with the structure of other established and related networks (e.g. flux tower networks, SAPFLUXNET). The database creation will be complemented by efforts to develop community-crafted protocols, best-practices, and analytical tools for soil and plant water potential observation and interpretation, with a particular emphasis on emerging techniques for continuous observation of water potential in-situ. Finally, the network will build a diverse “Community of Practice” to elevate the measurement, synthesis, and application of plant and soil water potential through early career training programs, community workshops, and novel teaching and outreach tools. In this talk, I’ll describe how these activities could provide the data, collaborative platforms, and training necessary to improve our predictive understanding of ecosystem water status and flows.
Field observations of interlinked subglacial cavities in Kangerlussuaq - Greenland ice sheet western margin.
Authors: Grau Galofre Anna , Noblet Axel
Published: March 2024

The glacial hydrology and stability to sliding episodes of the Greenland Ice Sheet (GIS) are closely linked to the subglacial drainage capacity of its bed, which depends on its structure and connectivity. The central-western portion of the GIS, specifically in the region around Kangerlussuaq, is characterized by subglacial drainage systems consisting on meltwater-filled cavities on a hard bed (Harper et al., 2017), which may become interconnected following episodes of increased discharge. Episodes of connectivity following high pressure subglacial meltwater events may lead to enhanced sliding followed by channelization, and emplacement of subglacial floods (Harper et al., 2017).We present preliminary field and remote sensing observations describing the morphology, topology, organization, and other field characteristics of recently exposed elements of the glacial hydrology system, which were emplaced by the western margin of the GIS. Our field site is located by the Europlanet Transnational Access TA1 Facility 4: Greenland-Kangerlussaq, which offers a unique opportunity to study the subglacial drainage patterns in this region (Carrivick et al., 2016). Few regions in the world offer the opportunity to study recently emplaced, well exposed subglacial morphologies at the level of accessibility of this site. Field data includes in situ-imagery, observations of glacial sliding directions, description of sedimentary deposits, morphology, scale and characteristics of subglacial cavities, and nature of the connection passages. Data acquired in the field is complimented with remote sensing data from the ArcticDEM and Maxar imagery.We conclude with a discussion of the implications of our observations for the geometry and volumetric capabilities of currently active subglacial hydrology pathways under the western portion of the GIS, including addressing the possible modes of meltwater drainage from the observed morphologies and subglacial geological reconstructions (e.g., White et al., 2016), as well as a comparison of the morphology and geometry of observed interconnected subglacial cavities to morphologically and topologically similar systems located at the east of Hellas Basin on Mars. 
Overlapping locality between rhizosphere and mycorrhizosphere regulates glucose exudation pattern in rhizosphere and enzyme distribution
Authors: Hoang Thi Thu Duyen
Published: March 2024

Glucose is one of the major primary metabolites in the plant root exudates to mediate the cross-talk between plants and microbes, but their contribution to drought resistance of plants is largely unknown. To test this, we inoculated arbuscular mycorrhizal fungi (AMF) in soybean, quantified rhizospheric microbial hotspots, visualized glucose exudation pattern, and analyzed microbial activities, such as kinetic properties of β-glucosidase and acid phosphomonoesterase enzymes, and microbial biomass phosphorus.Drought reduced glucose exudation, mainly allocated to root tips under optimum conditions, and narrowed the rhizosphere enzymatic hotspot by three times. However, AMF inoculation enhanced glucose exudation compared to non-mycorrhizal plants, and enlarged enzymatic hotspot area by 53% under drought condition. Despite the 50% reduction in β-glucosidase and acid phosphomonoesterase activities owing to water deficit, AMF symbiont triggered up to 36% enzyme activities in correlation with the non-mycorrhizal ones. Therefore, the drought resistance of these two enzymes was enhanced by up to 63% in mycorrhizal plants. The biomass of microbial phosphorus increased by 45% under drought conditions in plants inoculated with AMF.Overall, the greater resistance of enzyme activities to drought in AMF-inoculated than in non-mycorrhizal suggest that microorganisms associated with mycorrhizal root have higher capability to react to altered abiotic environmental conditions than those associated with non-mycorrhizal roots. The mycorrhization induced an interactive regulation of soybean glucose exudation and rhizosphere expansion for enzyme activities. This contributed to the resistance of microbial functions (e.g., enzyme expression) to drought stress in AMF-inoculated than in non-mycorrhizal soybean. AMF-inoculation suppressed adverse drought effects on plant and microbial nutrient mining, which has substantial implications for controlling microbial roles in organic matter decomposition and P cycling.Keywords: glucose imaging, arbuscular mycorrhiza fungi, soybean, hotspot, drought resistance
EPP-climate link by reactive nitrogen polar winter descent revisited: MIPAS v8 reprocessing and future benefits by the EE11 candidate mission CAIRT
Authors: Bender Stefan , Funke Bernd , Lopez Puertas Manuel , Garcia-Comas Maya , Stiller Gabriele , von Clarmann Thomas , Höpfner Michael , Sinnhuber Björn-Martin , Sinnhuber Miriam , Errera Quentin , Poli Gabriele , Ungermann Jörn
Published: March 2024

Polar winter descent of reactive nitrogen (NOy) produced by energetic particle precipitation (EPP) in the mesosphere and lower thermosphere affects polar stratospheric ozone by catalytic reactions. This, in turn, may have implications for regional climate via radiative and dynamical feedbacks. NOy observations taken by the MIPAS/Envisat instrument during 2002--2012 have provided observational constraints on the solar-activity modulated variability of stratospheric EPP-NOy amounts. These constraints have allowed to formulate a chemical upper boundary condition for climate models in the context of solar forcing recommendations for CMIP6. Recently, a reprocessed MIPAS version 8 dataset has been released. Compared to the previous version, we assess what impact the changes in this new data version have on the EPP-NOy quantification, and on the formulation of chemical upper boundary conditions for climate models.The Earth Explorer 11 candidate “Changing Atmosphere Infra-Red Tomography” (CAIRT) will observe the altitude region from about 5 km to 115 km with an across-track resolution of 30 to 50 km within a 500 km wide field of view. This instrument will provide NOy and dynamical tracer observations from the upper troposphere to the lower thermosphere with unprecedented spatial resolution. Given that neither MIPAS nor any of the current instruments observes the lower thermosphere at this spatial resolution, we will assess the potential of this mission to advance our understanding of the EPP-climate link in the future.
A detailed earthquake catalog using Machine Learning-based methods for Tuscany, Italy
Authors: Porras Juan , Michailos Konstantinos , Savard Genevieve , Montanari Domenico , Saccorotti Gilberto , Bonini Marco , Piccinini Davide , Piana-Agostinetti Nicola , Del Ventisette Chiara , Lupi Matteo
Published: March 2024

Seismic activity in Tuscany, Italy, is driven by the interplay between complex tectonics and local geological processes. Fluid-driven seismic sequences may occur in high-enthalpy geothermal regions, such as the Larderello-Travale Geothermal Field (LTGF), the oldest and among the most productive geothermal systems of the world. To better understand the regional tectonic setting, we build a detailed seismic catalog of earthquake hypocenters and magnitudes from a composite seismic network consisting of 30 temporary stations deployed in Tuscany in the framework of a temporary experiment (TEMPEST), during a period of one year (from September 2020 to September 2021) and 30 permanent seismic stations from the Istituto Nazionale di Geofisica e Vulcanologia (INGV).We applied an automated processing routine including a machine learning (ML) phase picker, PhaseNet, and the Gaussian Mixture Model Association (GAMMA) algorithm, a sequential earthquake association and location workflow. We initially obtain nearly 1 million P-phases and 2 million S-phases, yielding in around 5 thousand detected events. We then located the events with NonLinLoc and applied a quality factor metrics to filter out potential false detections (22%) and recognize the high quality solutions which represents 30% of the initial 5 thousand locations with moment magnitudes (Mw) ranging between 0.5 to 2.9, and depths generally shallower than 15 km. Further steps involve the location analysis of the remaining events from the initial catalog. Moreover, we will apply relative earthquake location methods to better constrain already evident seismicity clusters. We also plan to calculate focal mechanisms from first-motion polarities and Moment Tensor (MT) inversion to investigate the earthquake sources in the highlighted tectonic features.This work represents the starting point of the project “Multidisciplinary and InteGRated Approach for geoThermal Exploration” (MIGRATE). The goal of MIGRATE is to streamline passive seismic exploration methods for the investigation of geothermal resources, while addressing relevant scientific questions. This will result in the development of an automatized end-to-end tool to prospect the upper crust and identify potential geothermal targets.