bluuebunny/crossref_metadata_2025 huggingface dataset:
Crustal deformation of southwestern Tianshan orogenic belt based on InSAR and GPS observations
Authors: Wang Xiaohang , Motagh Mahdi , Xu Caijun
Published: February 2023

The Tianshan range, one of the most active mountain building belts in central Asia, has complex geological structures and frequent strong earthquakes since the Cenozoic. Due to lack of sufficient high-resolution geodetic survey measurments, little is known about detailed fault slip rates and seismic hazards related to main active faults in Tianshan. However, in recent years, the improvements in space-based geodetic technologies (Global Navigation Satellite System (GNSS) and interferometric synthetic aperture radar (InSAR)) with growing coverage and accuracy provide us an opportunity to image more subtle features in this area. In this study, we assesses inter-seismic deformation for the period 2014-2022 over the southwestern Tianshan based on ascending and descending Sentinel-1 SAR data.  Combined with GNSS data, we then constructed the 3D crustal deformation with high precision and high spatial resolution to study the active structures in southwestern Tianshan. The results indicate that: (1) The Tianshan orogenic belt (TSOB) has intense crustal deformation and the shortening rate is approximately 20 mm/yr. The Keping fold-thrust belt (KFB) is the most intensely deformed areas in TSOB, it’s convergence rate accounts for 1/3 of the entire southwestern Tianshan. (2) The South Tianshan fault (STF) and the Piqiang fault (PQF) have obvious left-lateral strike-slip components and the South Tianshan fault also has thrust characteristic. (3) The folds in both western and eastern KFB play an important role in accommodating regional strain, the shortening rate in KFB is accommodated by the thrust-anticlinal zone at the KFB front.
Contrasting responses of vegetation to intraseasonal rainfall in Earth System Models
Authors: L. Harris Bethan , M. Taylor Christopher , Quaife Tristan , P. Harris Phil
Published: February 2023

The response of vegetation productivity to water availability provides a key link between the carbon and water cycles. Correctly representing this response in Earth System Models (ESMs) is essential for accurate modelling of the terrestrial carbon cycle and the evolution of the climate system. To investigate how well models capture this relationship at intraseasonal timescales, we use global datasets based on satellite observations to assess the land surface response to intraseasonal precipitation events, and evaluate the performance of CMIP6 ESMs in representing this response in the recent historical period. Whereas models are able to capture the observed surface soil moisture (SSM) response with reasonable agreement, there are large inter-model discrepancies in the response of Gross Primary Productivity (GPP), both in magnitude and timing, even in regions where land cover is similar between models. In particular, ACCESS-ESM and NorESM produce much lower-amplitude GPP responses to rainfall than UKESM and CNRM-ESM. All the models studied are able to represent that the regional amplitude of the GPP response is positively correlated with the amplitude of the SSM response, and negatively correlated with the amplitude of the vapour pressure deficit (VPD) response. All models except NorESM also capture that stronger SSM responses are associated with faster GPP responses. However, the models differ in their sensitivity to these drivers, and can produce very different GPP responses from similar variations in SSM and VPD, particularly in climatologically dry regions. This highlights the need for a better understanding of the uncertainties in the representation of water-vegetation relationships in ESMs, such as the effect of atmospheric vapour pressure deficit on stomatal conductance and the control of soil moisture stress on GPP.
Syn-kinematic porosity evolution during nucleation and growth of stylolites (Eilean-Dubh limestone, NW Scotland)
Authors: Hou Zhaoliang , Fusseis Florian , Schöpfer Martin , Grasemann Bernhard
Published: February 2023

Stylolites are common microstructures in rocks, where mineral dissolution in a fluid localises in more or less discrete seams. Stylolite formation strongly affects rock porosity, pore connectivity and thus fluid flows. However, details of porosity evolution associated with stylolite nucleation, propagation and growth remain unclear, leading to the debate whether stylolites are conduits or barriers for fluids.In this contribution, we use an exceptionally large high-resolution SEM-BSE mosaic (102,600 × 18,239 pixels, 0.17µm/pixel) to investigate the detailed microstructures of stylolites from the Eilean Dubh limestone of the NW Highlands in Scotland. Advanced image analyses indicate that porosity self-organises systematically around stylolites suggesting a four-stage growth process for stylolites: In stage 1, primary pyrites in the rock matrix concentrate stress and dissolution, leading to the formation of porosity. In stage 2, the dissolution porosity self-organises, triggering a chemical-hydraulic-mechanical feedback loop that facilitates further dissolution. In stage 3, the porous zones enlarge and grow along the direction of the smallest principal stress (process zone), concentrating the synkinematic precipitation of pyrites from an external fluid in the core (core zone). In stage 4, the isolated domains connect forming a stylolite with a core zone in the center (highest porosity) surrounded on both sides by a process zones (higher-than-matrix porosity), suggesting a conduit phase during stylolite formation. Since the stylolite-hosting Eilean-Dubh limestones were episodically imbricated below the Ullapool thrust and the stylolites formed sub-parallel to the internal thrust planes, we speculate that synkinematic fluids during the stylolite formation were pumped episodically into the rock during activity of the Ullapool thrust. The detailed stylolite microstructures and the proposed process for stylolite growth suggest that stylolite in carbonate may act as a conduit for a fluid flow.
Hydrochemical Stimulation in Fractured Carbonate Rocks - Monitoring and Simulation
Authors: Bartels Jörn , Schätzl Peter , Baumann Thomas
Published: February 2023

Hydrochemical stimulation by acidification of geothermal wells is a standard procedure to remove drilling mud and to improve hydraulic contact between borehole and reservoir. Several successive stimulations using hydrochloric acid were monitored by both online measurement and conventional analysis. The results show recovery curves with distinct two-step exponential temporal decrease of the chloride concentration. The initial decrease is fast, representing water and acid flow along pathways which are very well connected to the borehole. After the fluid from these flow paths has been recovered, the concentration decreases at a lower rate. This can be attributed to water flowing in less well connected flow paths. With additional stimulations the chloride concentration curve approaches a mono-exponential decrease. This indicates that the flow paths within the reach of the stimulation get more homogeneous.A numerical model of flow and solute transport in the borehole and the surrounding geothermal reservoir was developed in order to simulate the observed chloride-recovery behaviour in the course of a number of successive hydrochemical stimulations. The finite-element model was adapted to match the observed hydraulic and hydrochemical data range.Simulation hereby allows to separate time-dependent single contributions from the different flow paths to the total recovery concentration. Based on this information, indications of structural change due to the successive acidification steps can be derived from the chloride-recovery curves of each step. Furthermore, for typical settings the minimum time and volume of solution can be estimated which is required to achieve a significant structural signalThe derived structural information can be useful to predict the long-term behaviour of a geothermal injection well which during operation is exposed to a mild but constant chemical stimulation by the injected cold and, with respect to chloride in the rock matrix, undersaturated water. 
Globally consistent, open-source river flood impact model using open data
Authors: Riedel Lukas , Röösli Thomas , Probst Pamela , Bey Isabelle , Bresch David N.
Published: February 2023

River floods are amongst the most devastating natural hazards. Reliable information on impeding hydrometeorological events enables humanitarian agencies to take action and to support the efforts of authorities and affected residents. Forecasting the socioeconomic impacts of such events improves focused measures to protect livelihoods. At the Federal Office of Meteorology and Climatology MeteoSwiss, we develop a globally consistent river flood impact model based on river discharge forecasts by the Global Flood Awareness System (GloFAS) and river flood hazard maps to support the humanitarian community.
 

Daily probabilistic river discharge forecasts of GloFAS are released by the Copernicus Emergency Management Service and can be downloaded from the Copernicus Climate Data Store. Global river flood hazard maps for flood events of different magnitude are available from the Joint Research Centre Data Catalogue of the European Commission. Additionally, the global database of flood protection standards FLOPROS is freely accessible. These open data collections enable the computation of forecasted, globally consistent river flood hazard footprints considering regional protection standards. With these footprints, we compute timely socioeconomic impact forecasts using the open-source, probabilistic impact model CLIMADA.
 

In this presentation, we demonstrate the new river flood module implemented in CLIMADA, which automatically downloads GloFAS data, computes flood footprints, and calculates flood impacts. We further discuss the benefits of impact forecasts for anticipatory action and disaster relief efforts compared to forecasts based on physical hazards alone.
Assessment of short-range forecast atmosphere-ocean cross-covariances from the Met Office coupled NWP system
Authors: Lawless Amos , Valdivieso Maria , Nichols Nancy , Lea Daniel , Martin Matthew
Published: February 2023

As part of the design of future coupled forecasting systems, operational centres such as the Met Office are starting to include interactions between the atmosphere and the ocean within the data assimilation system. This requires an improved understanding and representation of the correlations between short-range forecast errors in different variables. To understand the potential benefit of further coupling in the data assimilation scheme it is important to understand the significance of any cross-correlations between atmosphere and ocean short-range forecast errors as well as their temporal and spatial variability. In this work we examine atmosphere-ocean cross-covariances from an ensemble of the Met Office coupled NWP system for December 2019, with particular focus on short-range forecast errors that evolve at lead times up to 6 hours.We find that significant correlations exist between atmosphere and ocean forecast errors on these timescales, and that these vary diurnally, from day to day, spatially and synoptically. Negative correlations between errors in sea-surface temperature (SST) and 10m wind correlations strengthen as the solar radiation varies from zero at night (local time) to a maximum insolation around midday (local time). In addition, there are significant variations in correlation intensities and structures in response to synoptic-timescale forcing. Significant positive correlations between SST and 10m wind errors appear in the western North Atlantic in early December and are associated with variations in low surface pressures and their associated high wind speeds, that advect cold, dry continental air eastward over the warmer Atlantic ocean. Negative correlations across the Indo-Pacific Warm Pool are instead associated with light wind conditions on these short timescales.When we consider the spatial extent of cross-correlations, we find that in the Gulf Stream region positive correlations between wind speed and sub-surface ocean temperatures are generally vertically coherent down to a depth of about 100m, consistent with the mixing depth; however, in the tropical Indian and West Pacific oceans, negative correlations break down just below the surface layer. This is likely due to the presence of surface freshwater layers that form from heavy precipitation on the tropical oceans, manifested by the presence of salinity-stratified barrier layers within deeper isothermal layers that can effectively limit turbulent mixing of heat between the ocean surface and the deeper thermocline.
Random forest algorithm for long-gap imputation in Eddy Covariance data: a case study in an upland semi-natural grassland in the Auvergne region
Authors: WINCK BRUNA , BLOOR JULIETTE , KLUMPP KATJA
Published: February 2023

Eddy covariance techniques are widely used to measure the net exchange of greenhouse between the surface and the atmosphere, providing high resolution, instantaneous flux measures and long-term observations, which in turn allows more accurate assessments of the ecosystem’s state. However, gaps in eddy covariance time series reduce the statistical efficiency and increase bias estimates, hampering predictions of ecosystem function. Although, several imputation techniques have been proposed to overcome these difficulties, including Marginal Distribution Sampling (MDS), the standard method of FLUXNET, MDS has limitations for filling long gaps (weeks to months). In this study, we combine MDS and machine learning imputation techniques to fill an 18-year time series of carbon fluxes. Our objective was to evaluate whether Random Forest algorithms are able to fill long-gaps and detect seasonality, as well as to identify the best predictors of ecosystem exchange, gross primary productivity, and ecosystem respiration. The eddy covariance raw-data were obtained from an experiment in an upland semi-natural grassland in the Auvergne region of France that has been managed by continuous cattle grazing under low animal stocking rate.  After raw-data processing using EddyPro software, we applied the MDS technique to half-hour data to fill the short-gaps, and then used a Random Forest (RF) algorithm to daily data to fill longer gaps. The time series was split into a training and testing dataset, and all variables describing atmospheric conditions, solar radiation, and energy fluxes were used to predict C fluxes. Random Forest models with high R2 and low prediction error increases were used to impute the long-gaps.  The cross-validation between observed and predicted values in the test dataset obtained R2 of greater than 0.85 for all carbon flux variables. Our analysis also revealed that the daily carbon flux values could be estimated using the basic meteorological variables, i.e., air temperature, precipitation, atmospheric pression, friction velocity, and wind speed, but also by energy fluxes. Finally, the imputed dataset presented similar seasonality along the years, with the highest C sequestration and respiration in the summer and spring. These results highlight the value of machine learning techniques for producing robust, long-term eddy flux data time series.
3C natural abundance for analysis of steps of organic carbon transformation in soil: application for various ecosystems
Authors: Wang Ying , Gunina Anna , Kuzyakov Yakov
Published: February 2023

Following the developed concept of carbon (C) flows during soil organic matter (SOM) formation, from which the probable C pathways between the aggregates and SOM fractions can be suggested based on the natural changes of the 13C/12C ratios, we have prepared the review based on 42 publications. The data were collected from the existing databases using the following keywords: “soil organic matter fractions and 13C”, “density fractionation and 13C”, and “soil aggregates and 13C”; publications contained the data from forest, shrubland, grassland, and cropland ecosystems that were located in the Temperate, Mediterranean, subtropical and tropical climatic zones were chosen; only the top 20 cm were considered. Besides the δ13C data, the main soil properties, including pH, total C and nitrogen contents, texture, and the dominant type of soil minerals, were collected. All data for the isotopic composition of aggregates (>2000, 250-2000, 52-250, and <53 µm) and density fractions (<1.4, 1.4-1.6, 1.8-2.0, and >2.2 g cm-3) were normalized to the δ13C values of bulk soils. The preliminary analyses have shown that the isotopic composition of density fractions separated from the soils allocated in temperate and Mediterranean climates followed the previously established order, namely was getting heavier with the increase of particle densities. In contrast, density fractions separated from the soils of subtropical and tropical zones did not show prominent trends, or isotopic composition showed the enrichment in 12C with increased particle density. The isotopic composition of fractions separated from forest soils was also found with more minor variations compared to cropland and grassland. The data related to the probability of C flow between the density fractions and aggregates during SOM formation were also calculated and will be presented, as well as the concept explaining the effect of land use and climatic variables on the changes of the isotopic composition of density fractions and aggregates.
DIVEnet, an example of drilling monitoring
Authors: Guardo Roberto , Salimbeni Simone , Molinari Irene , Pondrelli Silvia , Cavaliere Adriano
Published: February 2023

The DIVEnet is the ICDP DIVE project dedicated seismographic network. The ICDP DIVE project (www.dive2ivrea.org) is aimed at addressing fundamental questions on the nature of the lower continental crust and its transition to the mantle through two drillings in the Ivrea Verbano zone (IVZ), considered the world's best outcrop of lower crustal continental rocks. Between September and December 2022 the first drilling has been done in Ornavasso. To be ready for its monitoring the DIVEnet has started to record continuously since November 2021. 
The network includes 11 seismic stations located within a 17.7 km radius from the drilling site. Additionally, the stations from the CH (Switzerland), GU (University of Genova) and IV (INGV) networks are used to locate the detected earthquakes. 

Before the beginning of the drilling the acquired data have been analyzed checking for daily and sub-daily continuity and, when needed, recovery acquisition gaps. After the data recovery, the total loss in the period span between November 2021 and 20 December 2022, date when the drilling stopped, is less than 2% and 5% in daily and sub-daily missing data, respectively. 
Furthermore, probabilistic power spectral densities (PPSD) analysis has been conducted monthly and for the entire period (11-2021 / 12-2022).

The drilling started on the 6 of October, showing no significant changes in the noise spectrum at each station, included those close to the drilling site. Real time analysis has been conducted from the beginning of the drilling with the automatic detection of local earthquakes counting less than 20 small events in the period between 1 October and 20 December.

Several automated codes have been developed to daily analyze, localize and eventually plot on map the events falling inside the network. Currently the workflow include a set of Python scripts followed by SeisComP calls for automatic earthquakes detection and localization;  the set of scripts comprises codes to: daily checks for earthquakes, weekly checks for gaps and, if necessary, download lost data, monthly analysis of PPSD and HTML-report creation with map location earthquakes. 

This routine would make future analysis faster and cleaner during the second drilling planned in Megolo in spring 2023 as well as other real time seismic analysis.
Urban tree water demand: Comparison of modeling results to measured sapflow and soil moisture data
Authors: Tams Laura , Kluge Björn , Paton Eva Nora
Published: February 2023

Current shifts in rainfall and temperature regimes towards dryer and hotter periods in central Europe have caused substantial water stress for urban trees.  To be able to adapt water supply to urban trees under a changing climate,  a quantification of evapotranspiration and water availability becomes necessary and is at the same time, very challenging in the heavily modified urban environments. Both processes are influenced by soil sealing and complex shading patterns of the surrounding street canyon.  For five urban street trees in the city center of Berlin, evapotranspiration rates and water availability was monitored in a field campaign (sapflow measurement and soil moisture in different depth) during the vegetation period of 2022. The monitoring results were then used to test a hydrological urban tree model with an integrated shading model which specifically takes into account the shading and sealing variability of the surrounding built environment.Both measured and modelled data a  show that potential evapotranspiration rates were significantly larger for trees with full sun exposure compared to shaded trees. At sites with full sun exposure, the increased evapotranspiration also reduced soil moisture content faster; at the same time measured actual evapotranspiration was reduced by up to 2/3 during water stress periods.In conclusion, the comparison showed that our model is a promising option to obtain information on water availability and to improve water management for urban trees under different shading and sealing environments in heavily modified cities. The tool will be further developed to be used by local authorities and practitioners to identify water shortage periods and hot spots  within the city to optimize irrigation efforts.Key words: urban trees, evapotranspiration (ET), water availability, water stress, water management,  urban environment, shading
Non-classical, non-linear elasticity in rocks: experiments in a triaxial cell with pore pressure control
Authors: Asnar Manuel , Sens-Schönfelder Christoph , Bonnelye Audrey , Dresen Georg
Published: February 2023

In rocks and concrete, dynamic excitation leads to a fast softening of the material, followed by a slower recovery process where the material recovers part of its initial stiffness as a logarithmic function of time. This requires us to exit the convenient framework of time independent elastic properties, linear or not, and investigate non-classical, non-linear elastic behavior. These phenomena can be observed during seismic events in affected infrastructure as well as in the subsurface. Since the transient material changes are not restricted to elastic parameters but also affect hydraulic and electric parameters as well as material strength, as documented for instance by long lasting changes in landslide rates, it is of major interest to characterize the softening and recovery phases. It may help us gain more insight in hazard prediction from both a geological and engineering perspective. The underlying physics behind those non-classical, non-linear effects, sometimes referred to as “Nonlinear Mesoscopic Elasticity”, are not agreed upon. There is a lack of experiments that would allow us to discriminate between the existing models.: we aim to contribute to filling that knowledge gap.Our experiments are made on a sample of Bentheim sandstone, initially dry and then fully saturated, in a triaxial cell. We subject the sample to loading and holding cycles in the microstrain range, while also varying confining pressure and pore pressure. Active acoustic measurements during those loading cycles with an array of 14 piezoelectric sensors allow us to monitor relative velocity changes during the experiment by using Coda Wave Interferometry (CWI).We observe the dynamic softening as well as the recovery processes in the sample during repeated loading phases of different durations. We find that characteristics of the observed velocity changes vary depending on the observed sensor combination, indicating spatial variability of the response, as well as depending on the lapse time and frequency content of the acoustic measurements that we perform the CWI on.These experiments serve to estimate the exact capabilities of our experimental setup in terms of signal quality, signal stability and lapse time dependent decorrelation of coda waves. We expect our results to inform a future series of similar but more refined experiments addressing the pore pressure dependence of the non-classical response of rocks.
Evaluation and correction of precipitation data obtained with different measurement methods using data from precision lysimeter network
Authors: Puetz Thomas , Schnepper Tobias , Gerke Horst H. , Reichert Barbara , Groh Jannis
Published: February 2023

Accurate precipitation measurements are essential for various applications such as determining the water balance of ecosystems and modelling soil-water fluxes in the earth critical zone. Gauge based point precipitation measurements are affected by wind, gauge design, and maintenance of the device. Ground-level gauges, like high precision weighing lysimeters, are less affected by environmental factors and thus provide more accurate data if well managed and the data are post-processed with filters. However, studies evaluating precipitation measuring methods with lysimeter references at multiple sites with high temporal resolution and detailed weather data are rare.In the present study, high-precision weighing lysimeter precipitation data from four years of measurement with an hourly resolution were used as references to evaluate data from four different precipitation measurement methods at three sites under different climatic conditions. The methods were tipping bucket gauges (TB), weighing gauges (WG), acoustic sensors (AS), and laser disdrometers (LD). Different sites and climatic conditions were chosen to be able to draw conclusions as to whether deviations between the measurement and comparison data were environment-dependent or unit-specific. Methodically, the evaluation included correlation analyses, comparison of catch ratios, x-y scatter plots, and the application of correction schemes.For the total period, all measurement methods recorded less precipitation than the lysimeters, with catch ratios between 33 to 92 % depending on the measuring method. Non-rainfall water inputs, like dew and fog, have been excluded for this study, therefore the measuring differences are attributed to the precipitation gauges. The bias of the hourly measurements varied between -0.69 to -0.01 mm h-1 based on the measuring method and no site-specific influence on the data was detected. Correction algorithms reduced the bias and improved the catching ratios of hourly precipitation data with similar improvements at all sites for the same gauge models, thus one adequate correction scheme may be sufficient to be used for the same model under different climatic conditions and environments. The findings suggest that a correction of the data by empirical or mathematical models appears to be necessary to ensure the quality of the precipitation data and to reduce over- and underestimations, which is the prerequisite for environmental studies in the critical zone.
Fossil fuel CO2 emission signatures over India captured by OCO-2 satellite measurements
Authors: Chen Jia , Balamurugan Vigneshkumar
Published: February 2023

Recent developments in space-based measurements provide new possibilities for monitoring greenhouse gas (GHG) emissions at all scales, from global to local. We traced CO2 emission sources such as power plants over India using OCO-2 satellite measurements from 2014 to 2021. India is the third-largest CO2 emitter in the world, with coal accounting for nearly 60% of total fossil fuel combustion.The Gaussian plume model was used to assess the power plant emissions. Cross-sectional (c/s) CO2 emission flux is estimated to validate the results. In 13 out of 26 cases, the estimated power plant CO2 emissions agreed within ± 25% of the emissions reported in the Carbon Brief (CB) database, and in 21 cases, the estimated emissions are within ± 50%. There is one case where the CB database significantly overestimated the CO2 emission for power plants. Further, in two cases, in which the Gaussian plume model gives much higher estimated CO2 emissions, there are emission sources other than the power plants in the vicinity. The c/s emission flux and emission inventories can be used to confirm such cases. In addition, the c/s emission flux method was employed to assess the emissions reported in the EDGAR and ODIAC CO2 emission inventories. Our study demonstrated the capability of OCO-2 to uncover missing or underestimated CO2 emission sources in emission inventories. Our approach could be a vital tool to conduct an initial estimate of missing or underestimated sources in the databases and emission inventories at various scales, as c/s emission flux estimation and Gaussian plume model require less computation than other modeling approaches. More sophisticated methods, such as Bayesian inversion combined with extensive transport modeling, can then be used to derive emissions with less uncertainty. Future satellites with high spatio-temporal resolution and coverage (e.g., Microcarb, Tansat2, CO2M) will enhance the possibilities of continuous monitoring of point sources as well as detecting missing or underestimated emission sources. 
Geomorphic evidence of ice stream shut down within the Iceland Ice Sheet, northeast Iceland
Authors: Aradóttir Nína , Benediktsson Ívar Örn , Ingólfsson Ólafur , Farnsworth Wesley , Brynjólfsson Skafti
Published: February 2023

Both modern and palaeo ice streams experience shut down which has critical implications for their mass balance and influence on relative sea level rise. Reconstructions of palaeo-ice streams have mainly focused on their phase of active flow but less is understood of their shutdown and style of deglaciation. Mapping of streamlined subglacial bedforms (SSBs), including drumlins and mega scale glacial lineations (MSGLs), in NE-Iceland reveals cross-cutting flow-sets of palaeo-ice streams within the Iceland Ice Sheet (IIS) during and following the Last Glacial Maximum (LGM). Here we map geometrical ridges (linear and reticular) in the Bakkaflói and Þistilfjörður areas and combine the morphological data with sedimentological analyses to increase our understanding of the dynamics of the IIS in NE-Iceland. We interpret the ridges as crevasse-squeeze ridges (CSRs), based on their interconnected network, primary orientation transverse and/or oblique to former ice flow, and internal composition of homogenous subglacial till. In both areas, the CSRs are superimposed on the SSBs, indicating that they post-date the formation of the SSBs and signify the waning stage of ice streaming associated with the readvance of the IIS during the Younger Dryas period. The preservation of the CSRs suggests ice stagnation following the readvance and ice stream shutdown. The morphological variance of the CSRs between the flow-sets may indicate different spatial-setting within the ice streams; the linear CSRs in Bakkaflói formed further upstream (dominated by extensional forces parallel to ice flow). Comparatively, the reticular CSRs in Þistilfjörður are more characteristic of the down-ice region (effected by mixed mode of transverse and longitudinal forces), proximal to the ice margin or piedmont. Future research reconstructing past glacial behaviour and ice dynamics would benefit from high-resolution bathymetric data from the adjoining shelf as well as enhanced geochronological constraints.
Human and natural drought impacts on groundwater fluxes of non-Amazonian South America
Authors: Vega Briones Jorge , de Jong Steven M. , Sutanudjaja Edwin , Wanders Niko
Published: February 2023

The consistent impact of droughts and the progressive use of groundwater for the superficial allocation of crops has extremely increased groundwater withdrawal. The rapid economic expansion is increasing water usage and is likely to exacerbate hydrological drought. While global drought intensities are increased by 10–500\% due to human water consumption, the consequences at a regional and global scale are aggravated by changing precipitation patterns, resulting in multi-year droughts and decreased groundwater recharge. An essential factor to better understand how human activities affect drought characteristics and development is to quantitatively distinguish natural and human components. At the same time, we see that the recovery from a severe drought is also impacted by catchment characteristics and regional climatology. In this study, we focus on the south American non-Amazon region which has frequently experienced multi-drought periods with severe impacts on surface and groundwater.We estimate the drought impact on groundwater with the model PCR-GLOBWB2 at a 5 arcmin resolution under natural and human influence. Aggregations of the model output at a catchment level of the groundwater and subsurface partitioned run-off was performed. To determine the influence with and without lateral water flux at high resolution, the flux differences of groundwater components such as baseflow and groundwater recharge were quantified. Finally, the drought termination (DT) framework was applied to understand the recovery response of simulated surface runoff, interflow, and groundwater recharge.The PCR-GLOBWB2 identifies regions influenced by human impact in the non-Amazon basins, supported by the drought duration, deficit, and groundwater fluxes. The differences in fluxes show an increasing groundwater withdrawal due to irrigated zones, affecting hydrological processes at a catchment and regional scale. The recovery of fluxes during these events consists of a relevant indicator for groundwater behavior due to drought and/or human consumption. We quantified the impact on groundwater resources by addressing the land-use component to understand the variability in water volumes. This study is beneficial to identify groundwater drought vulnerability in regions where observations are lacking and help to predict drought recovery periods, lateral-flux impacts, and characteristics.
Impact of socio-economic factors in burnt area for future climate scenarios
Authors: Teixeira João , Burton Chantelle , Kelley Douglas I. , Folberth Gerd , O'Connor Fiona M. , Betts Richard , Voulgarakis Apostolos
Published: February 2023

Fire processes are a complex component of the Earth System processes and their full representation has proven to be difficult to represent Earth System Models (ESM). Because of this, these processes are often simplified in fire enabled ESMs, for instance ignitions are usually modelled to increase at low population densities up to a threshold, and reduce thereafter, as suppression effects become dominant with the increase of population density. However, socio-economic, and cultural factors can play a significant role in shaping the behaviour of fire ignitions. This study aims to address this by implementing a socio-economic factor in the fire ignition and suppression parametrisation in the INteractive Fire and Emission algoRithm for Natural envirOnments (INFERNO) based on the Human Development Index (HDI). The inclusion of this factor reduced a large long-standing positive bias found in regions of Temperate North America, Central America, Europe, and Southern Hemisphere South America. This change also leads to improvements in the model representation of fire weather and anthropogenic drivers in tropical regions, by reducing the influence of population density changes. Therefore, this framework can be used to improve understanding of the anthropogenic impacts of fire in future scenarios based on different Shared Socioeconomic Pathways.
Integration of geophysical and geotechnical modelling to define hydrogeological conditions for unsaturated soils prone to shallow flowslides
Authors: Salone Rosanna , Pirone Marianna , De Paola Claudio , Forte Giovanni , Santo Antonio , Urciuoli Gianfranco , Di Maio Rosa
Published: February 2023

Flowslides, which occur mainly in shallow granular soils resting on bedrock, are among the most dangerous natural hazards to humans and utilities in both mountainous and volcanic areas. These phenomena are strongly controlled by the stratigraphic and topographic characteristics of the slope and the groundwater regime, which are commonly recognized as predisposing factors for the occurrence of flow-like landslides. Therefore, the study of the spatial variability of the local geological setting and hydrogeological conditions in partially saturated slopes is of fundamental importance for the prediction of flowslide events. In this framework, we propose a procedure based on 3D time-lapse electrical resistivity tomography imaging of the slope, integrated with geotechnical numerical modelling of hydraulic phenomena affecting the land cover, to analyse the effects of the stratigraphic variability in terms of geometry, continuity, and thickness of the soil horizons on the groundwater regime over time. The goal of the proposed approach is to set up an effective tool for predicting debris-flow landslides occurrence at the slope scale, thereby increasing the predictive capacity of early warning systems. The proposed multidisciplinary study was applied to the test site on Mt. Faito, in the northernmost part of the Lattari Mountains (Naples, Southern Italy), where loose pyroclastic deposits from the explosive eruptions of the nearby Somma-Vesuvius volcano cover a karst-fractured carbonate bedrock with a natural slope more than 30° steep. Specifically, seasonally repeated 3D electrical resistivity tomography surveys, suitably complemented with geological and geotechnical investigations, were carried out to determine the electro-stratigraphic and geological setting of the pyroclastic cover, the local morphology and physical conditions of the underlying carbonate bedrock, and the saturation degree distribution on a seasonal time scale. The latter was estimated through the resistivity vs. water content characteristic curves of the different soil horizons, which were obtained from laboratory measurements on specimens sampled in the survey area. The maps of the water content distribution within the pyroclastic cover, determined by the repeated field resistivity surveys, were validated by comparison with those obtained from 2D geotechnical numerical modelling aimed at simulating hydraulic phenomena affecting the soil cover. As main findings, the integrated approach showed that i)  the buried bedrock morphology heavily influences the pore water distribution in the soil cover and ii) ashy material fills the upper karst portion of the bedrock, providing a hydraulic connection of the water flow infiltrating from the topsoil downward.
Energy conversion by magnetic reconnection in multiple ion temperature plasmas
Authors: Dargent Jeremy , Toledo-Redondo Sergio , Divin Andrey , Innoncenti Maria Elena
Published: February 2023

This work investigates the energy transfer in the process of collisionless antiparallel magnetic reconnection and its dependance to the velocity distribution function of the inflowing plasma. We realised two two-dimensional semi-implicit PIC simulations of symmetric reconnection with exactly the same global parameters, but with different distributions of plasma: one simulation is loaded using Maxwellian distributions, while the other is the sum of two Maxwellian distributions, a hot one and a cold one, resulting in a very peaked distribution with large tails. We measure the increase of the bulk and thermal kinetic energies in both simulation for each population and compare it to the loss of magnetic energy through a contour surrounding the ion diffusion region. We show that the global energy budget for ions and electrons does not change depending on the distribution function of the plasma, but also that, when focusing on sub-populations, the hot ion population (i.e. the tail of the distribution) get more thermal energy than the cold ion population (i.e. the core of the distribution).
Variations of alpha particle parameters in the non-Alvénic wind
Authors: Durovcova Tereza , Šafránková Jana , Němeček Zdeněk
Published: February 2023

Spacecraft observations made at 1 AU from the Sun showed that the solar wind parameters are highly variable. D’Amicis and Bruno (2015) suggested that two solar wind regimes can be distinguished according to the nature of the embedded turbulent fluctuations. If the velocity and magnetic field variations are strongly correlated, Alfvénicity of the fluctuations is high, thus the first solar wind regime is called Alfvénic. Its characteristics suggest that it probably originates from coronal holes. The alpha particle parameters correspond to those usually associated with the fast solar wind. The alpha relative abundance is high (about 4 %) and alpha particles are faster and hotter than protons. The second solar wind regime has embedded non-Alvénic fluctuations. It could come from coronal streamers, but its formation remains unclear. Observations at 1 AU show that the non-Alvénic wind typically has the small alpha-proton relative drift and nearly equal temperature of both ionic components. In our study, we focus on variations of the alpha particle parameters in the non-Alvénic wind and on changes during transition from the Alfvénic to non-Alfvénic winds. We found observations of alpha particles slower than protons, for example near the termination of the corotating rarefaction regions. Using the WIND measurements, we perform a statistical study and compare the plasma properties associated with different ranges of the alpha-proton relative drift. Furthermore, we use measurements from the WIND and Solar Orbiter missions to study changes of the non-Alfvénic wind with increasing distance from the Sun. We discuss their possible origin both in terms of formation near the Sun and during propagation through the interplanetary space.
A Late Holocene δ18O paleoclimate record from the afro-alpine Lake Garba Guracha, Bale Mountains Ethiopia: implications for human occupation/abandonment
Authors: Chernet Samuel, Getachew , Bittner Lucas , Gil-Romera Graciela , Zech Michael
Published: February 2023

The Late Holocene, being a period when human footprint in paleoenvironmental archives became increasingly apparent, records important information about how early humans adapted to ever changing climatic conditions. Garba Guracha is an afro-alpine cirque lake located in the Bale Mountains National Park in the southeastern highlands of Ethiopia. The reconstructed age depth model with a time resolution of 10 years/cm makes it one of the best climate archives in the highlands of Eastern Africa. A total of 15.5 meter core recording 16 ka of sedimentation was retrieved from the lake. Previous works done on the archive include: (i) establishing the age-depth model and determination of sedimentation rates using bulk sedimentary organic matter, bulk n-alkane and charcoal 14C ages (Bittner et al. 2020); (ii) multi-proxy paleoenvironment reconstruction using charcoal, diatoms, biomarkers, and stable isotopes (Bittner et al., 2022; Gil-Romera et al., 2019). Results from these works show a strong variability for the late Holocene that represents the termination of the African Humid Period (AHP) and increased fire intensity. This study focuses on the topmost sedimentary succession of the core representing the late Holocene (~5 ka to present) and implements δ18Osugar extracted from organic matter derived sugar biomarkers in high resolution (every 4 cm). The δ18Osugar record can be used for reconstructing the lake evaporation history. Furthermore, combing these new data with other data obtained from n-alkane, charcoal and archaeological studies will shade light on a possible climate human interactions in high alpine ecosystem.ReferencesBittner, L., Bliedtner, M., Grady, D., Gil-Romera, G., Martin-Jones, C., Lemma, B., Mekonnen, B., et al., 2020. Revisiting afro-alpine Lake Garba Guracha in the Bale Mountains of Ethiopia: rationale, chronology, geochemistry, and paleoenvironmental implications. Journal of Paleolimnology 64, 293–314.Bittner, L., Gil-Romera, G., Grady, D., Lamb, H., Lorenz, E., Weiner, M., Zech, M. (2022). The Holocene lake-evaporation history of the afro-alpine Lake Garba Guracha in the Bale Mountains, Ethiopia, based on δ18O records of sugar biomarker and diatoms. Quaternary Research, 105, 23-36.Gil-Romera, G., Adolf, C., Benito Blas, M., Bittner, L., Johansson, M.M.U., Grady, D.D.A., Lamb, H.H.F., et al., 2019. Long-term fire resilience of the Ericaceous Belt, Bale Mountains, Ethiopia. Biology Letters 15, 20190357. 
Rapid minero-chemical classification of volcanic ash and inorganic dust at PM10 level: the longer-term effects of short-term hazards in the Canary Islands.
Authors: Coldwell Beverley , Wertheim David , Myashita Lisa , Gill Ian , Crust Simon , Giddens Richard , Grigg Jonathon , Pérez Nemesio , Petford Nick
Published: February 2023

Environmental exposomes in the natural environment include silicate ash from volcanic eruptions and wind-blown mineral dust, both of which may promote lung disease if subjected to prolonged exposure. In order to develop strategies for risk mitigation in populations subjected to hazardous minerals in the environment, it may be useful to integrate mineral chemical composition with the three-dimensional particle characteristics (e.g. shape and surface characteristics) as a means to fully assess potential mechanisms of toxicity. In this contribution we show how a combination of confocal laser microscopy, a non-destructive technique capable of resolving true 3D geometry of PM10 and PM2.5 particles, with spectroscopic analysis, provides a novel and rapid way to assess the minero-chemical properties of potentially hazardous airborne material (Wertheim et al. 2017).Initial results using samples from the 2021 La Palma volcanic eruption (volcanic silicate ash) show that volcanic particles (angular forms) increased pneumococcal adherence to A549 lung epithelial cells in vitro (Miyashita et al. 2022). Preliminary confocal images of airborne mineral dust originating in Saharan Africa and deposited on Tenerife during a sandstorm (Calima event, February 2020), show more rounded, mature particle shapes than volcanic ash, yet with clear variations in surface features. Hence we are investigating whether Calima particles could also affect pneumococcal adherence to lung cells in vitro.Applying such a multidisciplinary approach combining results from different techniques may help to raise awareness of and prevent longer-term occupational hazards in populations such as the Canary Islands, where residents are at risk of multiple sources of exposure to both volcanic ash and inorganic dust.ReferencesWertheim D, Gillmore G, Gill I, Petford N. High resolution 3D confocal microscope imaging of volcanic ash particles. Sci Total Environ. 2017 Jul 15;590-591:838-842. DOI: 10.1016/j.scitotenv.2017.02.230.Miyashita L, Coldwell B, Wertheim D, Giddens R, Gill I, Petford N, Pérez N and Grigg J. La Palma Volcanic Ash Particles Increase Susceptibility to Pneumococcal Infection In Vitro. European Respiratory Journal 2022 60: 3163; DOI: 10.1183/13993003.congress-2022.3163