bluuebunny/crossref_metadata_2025 huggingface dataset:
Towards confidence in numerical modeling of ice stream cycling
Authors: Hank Kevin , Tarasov Lev , Mantelli Elisa
Published: February 2023

Some ice sheets and glaciers experience long quiescent periods interspersed with short periods of rapid ice advance, such as the binge-purge-type cycling hypothesized to be associated with Heinrich Events. Modeling ice stream activation/de-activation, however, is numerically challenging given the relatively abrupt changes at surge onset and the high ice velocities. In spite of this, a number of high-profile modeling papers have explored Heinrich events and ice surges, but generally with very limited consideration of numerical aspects. Here we test the ability of the 3D Glacial Systems Model (GSM) and Parallel Ice Sheet Model (PISM) to simulate binge-purge-type surges and explore the stability of the simulations with respect to relevant numerical and discretization uncertainties. We find surge characteristics exhibit a resolution dependency but converge at higher horizontal grid resolutions (order 5 km). In accordance with theoretical and experimental work, our model results suggest that the thermal activation of basal sliding should start below the pressure melting point. A resolution-dependent basal temperature ramp for the thermal activation of basal sliding as well as a subglacial hydrology model can reduce the discrepancies between high and coarse horizontal grid resolutions. Furthermore, incorporating a bed thermal and at least a minimal complexity subglacial hydrology model significantly affects surge characteristics and is, therefore, essential for modeling large-scale ice stream cycling.
Mapping of radioactivity levels in and around the gold mine tailing dams of Gauteng Province, South Africa
Authors: Moshupya Paballo , Mohuba Seeke , Abiye Tamiru , Korir Ian
Published: February 2023

Naturally occurring radionuclides arises mainly from natural sources and anthropogenic activities such as mining. In South Africa, gold mining in the goldfields of the Witwatersrand Basin has resulted in numerous tailing dams that have high concentrations of NORM bearing residue. The aim of this study was to evaluate the surface radioactivity levels in and around the gold tailing dams of Gauteng Province in South Africa and further determine the consequential radiological exposure to the public. The portable BGO SUPER-SPEC (RS-230) spectrometer, with a 6.3 cubic inches Bismuth Germanate Oxide (BGO) detector was used to measure the activity concentrations for 238U, 232Th and 40K in mine tailings, soils and underlying rocks. This work was conducted on a regional scale and covered the West Rand, East Rand and Central Rand Districts of the Gauteng Province, which are dominated by the abandoned gold tailings dams. Of the three radionuclides that were studied, 238U was found to be the most significant radioactive contaminant of radiological concern. High 238U concentrations (209.95 to 2578.68 Bq/kg) were found in the mine tailings than in the surrounding soils (9.88 to 941.07 Bq/kg) and rocks (11.12 to 71.63 Bq/kg). In surface soil, the radionuclides show significant spatial variability with high activities recorded in soils located in close proximity to tailings thus signifying the adverse environmental impacts of mining in the study area. The annual effective dose estimations indicate that the mine tailings found in the area and soils impacted by tailings significantly contribute to the external gamma radiation received by members of the public. This therefore highlight the need for further monitoring and regulatory control measures targeting these affected areas, in order to ensure the protection of persons and the environment within the areas.Keywords: activity concentration; gold mine tailings; in situ gamma ray spectrometry; radiologicalexposures; South Africa 
Global IDF curves created from local observations using machine learning
Authors: Hoch Jannis , Probyn Izzy , Bates Joe , Wing Oliver , Sampson Christopher
Published: February 2023

Intensity–duration–frequency (IDF) curves are representations of the probability that a given rainfall intensity will occur within a given period. At the global scale, however, only for a few locations sub-daily rain gauge data is available from which global IDF curves could be derived. This poses a major challenge for simulations of global pluvial flood hazard and risk which require information of intensity, duration, and probability as boundary conditions. Therefore, efficient yet accurate means for scaling the locally available data to the global extent need to be found.Consequently, we use available quality-controlled sub-daily precipitation data from the GSDR data set to derive growth curve parameters at around 10,000 locations world-wide. After combining these scale and shape parameters with globally available data of main precipitation drivers, a regionalized machine learning model is first trained and tested and then applied to produce global IDF maps.Finally, we evaluated these maps against an ensemble of openly available local IDF curves found in literature. By selecting locations spread across the globe, we try to ensure to include as much variability as possible in the evaluation. Additionally, the global IDF curves were benchmarked against available more bespoke IDF data in the USA and UK.While such data-driven approaches clearly depend on the quality and quantity of available sub-daily rainfall observations, the method still shows to capabilities of current data-driven modelling approaches to scale local data to global data applicable in both flood risk research and practice.
Probabilistic modelling of water distribution networks and resilient reduction of leakages: Large scale application to the city of Patras in western Greece
Authors: Serafeim Athanasios V. , Kokosalakis George , Deidda Roberto , Fourniotis Nikolaos Th. , Karathanasi Irene , Langousis Andreas
Published: February 2023

Modeling of leakages in Water Distribution Networks (WDNs) is a vital task for all water related professionals and experts towards the development of management practices and strategies, which aim at the reduction of water losses (leakages) and the associated financial cost and environmental footprint. In the current work we develop an integrated, theoretically founded, and easily applicable probabilistic framework for resilient reduction of leakages in WDNs, which combines: a) a set of conceptually and methodologically different probabilistic approaches for minimum night flow (MNF) estimation in WDNs based on statistical metrics (Serafeim et al., 2021 and 2022a), and b) a combination of statistical clustering and hydraulic modeling techniques for the rigorous and user unbiased partitioning of WDNs into pressure management areas (PMAs) or district metered areas (DMAs), which seeks for minimization of leakages while maintaining an acceptable level of the network’s hydraulic resilience (Serafeim et al., 2022b). The efficiency of the introduced framework is tested via a large-scale real-world application to the water distribution network of the City of Patras, the largest smart water network (SWN) in Greece, which covers an area of approximately 27 km2 and serves more than 213000 consumers (based on data from the Hellenic Statistical Authority and the Municipality of Patras), with more than 700 km of pipeline grid (mainly HDPE and PVC pipes).AcknowledgementsThe research work was supported by the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the “First Call for H.F.R.I. Research Projects to support Faculty members and Researchers and the procurement of high-cost research equipment grant” (Project Number: 1162).ReferencesSerafeim, A.V., Kokosalakis, G., Deidda, R., Karathanasi I. and Langousis A (2021) Probabilistic estimation of minimum night flow in water distribution networks: large-scale application to the city of Patras in western Greece, Stoch. Environ. Res. Risk. Assess., https://doi.org/10.1007/s00477-021-02042-9.Serafeim, A.V., G. Kokosalakis, R. Deidda, I. Karathanasi and A. Langousis (2022) Probabilistic Minimum Night Flow Estimation in Water Distribution Networks and Comparison with the Water Balance Approach: Large-Scale Application to the City Center of Patras in Western Greece, Water, 14, 98, https://doi.org/10.3390/w14010098.Serafeim, A.V., G. Kokosalakis, R. Deidda, N. Th. Fourniotis and A. Langousis (2022) Combining statistical clustering with hydraulic modeling for resilient reduction of water loses in water distribution networks: Large scale application to the city of Patras in Western Greece, Water, 14(21), 3493. https://doi.org/10.3390/w14213493. 
Influence patterns of soil moisture change on surface-air temperaturedifference under different climatic background
Authors: jiang kang
Published: February 2023

The surface-air temperature difference (Ts-Ta) is the main contributor to the sensible heat flux, and also an important indicator for land degradation. However, as the main influencing factor, the effect of soil moisture (SM) on Ts-Ta at the global scale has not been well articulated. Here, based on the ERA5-land reanalysis data from 1981 to 2019, the impacts of SM on Ts-Ta were studied. It was found that Ts-Ta over 54% of the global land increased, and SM across 70.7% of the world land decreased. In the increased SM areas, the increased soil evaporation weakened the increasing trend of Ts resulting in smaller Ts-Ta. In the decreased SM areas, the latent heat flux increased with soil evaporation and Ts-Ta decreased when SM was relatively high, and the larger sensible heat flux due to decreased soil evaporation aggravated Ts-Ta when SM was relatively low. The effect of SM on Ts-Ta presented nonlinear relationship due to the different background value of SM and temperature. The variation of SM at low SM or low temperature areas had an amplification effect on Ts-Ta. These findings will provide new insights into the different regional characteristics of global changing climate and the improvement of land degradation assessment indicators.
Precise orbits for the lunar navigation system: challenges in the modeling of perturbing forces and broadcast orbit representation
Authors: Sośnica Krzysztof , Zajdel Radosław , Bury Grzegorz , Di Benedetto Mauro , Durante Daniele , Sesta Andrea , Fienga Agnes , Linty Nicola , Belfi Jacobo , Iess Luciano
Published: February 2023

In the framework of the European Space Agency’s Moonlight program, a satellite navigation system is planned for positioning, navigation, timing, and communication on the Moon.  The constellation will consist of three or four lunar orbiters in eccentric orbits – with periselene above the northern hemisphere and aposelene above the southern hemisphere; the latter is of special interest in terms of future lunar missions. The eccentric orbits introduce a challenge for precise orbit determination, because large gravity perturbations due to the lunar gravity field occur in the periselene passes, whereas the aposelene passes are associated with the smallest gravity gradients and thus the largest errors in orbit determination.We evaluate the non-gravitational and gravitational perturbing forces acting on lunar orbiters in eccentric orbits. The simulated orbits consider lunar gravity field based on the GRAIL mission, gravity perturbations from the Sun, Earth, and planets considering Earth’s oblateness, tidal deformations, direct solar radiation pressure with lunar and Earth eclipses, albedo, antenna thrust, and relativistic effects. We discuss three methods of proposed representation of the broadcast orbits: based on Keplerian parameters and a set of one-per-revolution corrections (GPS-like or Galileo-like), based on Chebyshev polynomials with a variable number of coefficients and arc-length representation, and based on a series of positions and velocities (GLONASS-like). We discuss the advantages and limitations of all three representations and accuracies provided by different approaches depending on the number of assumed coefficients and arc lengths. Finally, we discuss the impact of inconsistent treatment of the origin, scale, and orientation of the lunar reference frame on the determined positions on the Moon. 
Characterizing the spatial coherence of mesoscale eddies using in-situ data
Authors: Barabinot Yan , Speich Sabrina
Published: February 2023

Ocean mesoscale eddies are ubiquituos in the global ocean. They are responsible of about 80% of the total eddy kinetic energy and are suggested to exert a significant impact on air-sea interactions, ocean large-scale circulation, weather and marine ecosystems. They have been qualified as "coherent" structures as they can leave for months if not years propagating in the ocean interior. As ocean observations are very sparse, they have been essentially characterized from satellite altimetry fields, which provides access to a limited number of surface characteristics of only those eddies having an imprint on sea surface height.  Observations of mesoscale eddies 3D structure, or even 2D vertical sections are rare.  On the other hand, accurate description of ocean eddies from high-resolution ocean numerical simuation are also limited. In general, they have been accoubted for via statistics, instead of individual descriptions as the latter is difficult as they move away from fixed positions. In this work we present a detailed study of ocean eddies (surface and subsurface intensified) sampled during 10 oceanographic cruises which have a sufficient horizontal spatial resolution of the vertical eddy sampling - 9 in the Atlantic Ocean (during experiments EUREC4A-OA, M124, MSM60, MSM74, M160, HM2016611, KB2017606, KB 2017618), and one in the Indian (during the Physindien 2011 experiment). Our study characterizes the eddy core and boundary in a generic way using diagnostics based on active (PV, oxygen) and passive (temperature, salinity) tracers. Despite the different resolutions of the eddy sampling in the 9 studied regions, we show that the 3D boundary of an eddy behaves like a frontal zone characterized by the Ertel PV where the water mass trapped in the eddy joins with the surrounding waters. Whatever the  origin and size of the eddy are, the core is homogeneous in properties with the anomaly maximum located at depth, which makes its altimetric characterization difficult. Moreover, these analyses provide a new metrix for defining the coherence of an ocean eddy, a concept that has been always ill-defined because of the elusive character and undersampling of these structures. 
Crop plant effects on denitrification – what have we learned in six years DASIM project?
Authors: Rummel Pauline Sophie , Well Reinhard , Pausch Johanna , Englert Paulina , Matson Amanda , Beule Lukas , Floßmann Sebastian , Eckei Jonas , Pfeiffer Birgit , Dittert Klaus
Published: February 2023

Denitrification in agricultural crop production is one of the main sources of gaseous N2O and N2 losses to the environment. To successfully develop mitigation strategies, it is crucial to understand N2O production pathways, but also to quantify all other gaseous N losses, especially N2 emissions. Therefore, this project aimed (1) to identify the main drivers of denitrification during plant growth and in the post-harvest period, (2) to quantify denitrification derived N2O and N2 losses during the cropping season, and (3) to assess the interactions between plant litter quality, initial litter degradation, and formation of hotspots of N2O and N2 production. We conducted experiments on the laboratory, greenhouse, and field plot scale using the 15N gas flux method and HeO2 atmosphere to directly measure N2O and N2 losses and to determine the fraction of denitrification derived N losses. We worked with soils, crops, temperature and moisture conditions that are typical for our central German humid-temperate climate.Plant growth affected all controlling factors of denitrification, especially soil moisture, NO3− and Corg availability. Crop species differed in their growing patterns and N uptake throughout the growing season controlling both N and C availability in soil. Accordingly, N2O and N2 emission patterns differed between crop species. Overall, emissions were highest when plant N uptake was low, i.e., during early growth stages and ripening, and after harvest. On the field scale, soil moisture and temperature were major controls of N2O+N2 losses.In a climate chamber study under controlled temperature conditions, N2O and N2 fluxes mainly derived from denitrification of labeled 15NO3− in anoxic microsites, while nitrification simultaneously occurred in more oxic parts of the soil, potentially contributing to formation of unlabeled N2O. Increasing soil moisture with irrigation increased denitrification rates in anoxic hotspots, which corresponded with increasing N2O and especially N2 fluxes. At the same time, it restricted nitrification and thus decreased the share of nitrification-dependent processes contributing to N2O formation.Incorporation of plant litter increased CO2, N2O, and N2 losses irrespective of litter quality, soil moisture or soil type/SOM content. We found that under O2 limiting conditions (70 % WFPS), the fraction of easily degradable C controlled the magnitude of N2O and N2 losses after litter incorporation. Under moderate soil moisture (50-60 % WFPS), interactions between litter degradation and SOM turnover affected the time course and processes contributing to N2O formation. Overall, our high-resolution gas flux measurements showed that N2O+N2 emissions from harvest residues can contribute significantly to the total N loss. 
Flood risk assessment of educational and health critical facilities
Authors: Bertoli Gabriele , Arrighi Chiara
Published: February 2023

Critical facilities are crucial buildings for the community and in case of natural hazards their functionality must be guaranteed. Specific building codes and up-to date studies are commonly available for facing earthquakes, but it is not the same for other natural hazards, such as floods. The older facilities might stand in flood prone areas, but from the recent years such structures are usually built far from the major river network and outside the known inundation areas. Probably this is the most common and, sometimes, the only, mitigation measure adopted against floods. Also, moving critical facilities far from the main river network, means that they are settled near and over the secondary river network, which is often not known in-detail and characterized by small basins with sudden responses, high urbanization, and with heavy modifications to the natural existing drainage system. Moreover, critical facilities are seldom included in flood risk analyses, especially regarding the indirect impacts. The work is based on a case study area located in Florence (Italy), where one major hospital of the central Italy and one relevant learning center of University of Florence are built over a culverted stream, surrounded by the secondary hydrograph network, inside a set of small sub-basins. A hydrological analysis was carried out, and the hydraulic modeling of the stream was implemented with the help of geophysical prospecting. Particular attention was dedicated to the assessment of direct and indirect impacts of the hazard. The direct impacts were studied starting from a collection of all the building-specific installations and systems, then formulating a damage curve in function of the water height. The indirect and intangible impacts, which can worsen the impacts of the flood, were carefully researched and investigated taking in account factors, among others, as the building accessibility during and after the flood event, the expected service disruption time, the possibility of the structure to be used as shelter, the fluctuation of the number of people expected to be in the building during the event, the consequences on people and on the community of the service disruption, the seasonality impact. Eventually, a comprehensive damage (impact) evaluation technique was developed.
Detection of debris-flow initiation with seismic techniques for early-warning purposes
Authors: Ioriatti Elena , Coviello Velio , Comiti Francesco , Macconi Pierpaolo , Reguzzoni Mauro , Berti Matteo
Published: February 2023

In mountain regions, debris flows are responsible for major damage to infrastructure and many casualties every year. Early Warning Systems (EWSs) based on sensor networks installed along the debris-flow channel have been implemented in some catchments around the world, including the Alps. Detecting the early phase of debris flows would allow expanding the lead time of an EWS compared to the monitoring of channelized flows upstream a vulnerable site. In this study, monitoring data gathered from 2019 to 2022 in the headwaters of the Gadria catchment, eastern Italian Alps, are analyzed. One active channel located at 2200 m a.s.l. was instrumented with a time-lapse video camera, a tipping-bucket rain gauge, and a 4.5-Hz vertical geophone. The dataset includes 5 debris-flow events that propagated from the monitored channel to the basin outlet and a large number of signals produced by other seismic sources (e.g., rockfalls, earthquakes, animals, wind). The peak amplitude, the duration and the frequency content of the seismic signals were analyzed with the support of video images to identify the different seismic sources. Results show that different seismic sources produce signals with different characteristics and that it is possible to discriminate the most intense channel processes by analyzing seismic data only. Adopting an approach similar to the rainfall thresholds, debris-flow and runoff events have been bounded by means of a power relationship between peak amplitude and signal duration. The next step of the research would be the development of an algorithm able to automatically classify the seismic sources and identify intense channel processes that can generate debris flows. A similar approach will be applied to the Blé catchment (Val Camonica, central Italian Alps) to study the triggering mechanisms and dynamics of debris flows and analyse whether the proposed approach is valid in other locations. The analysis of seismic data will be combined with the identification of triggering rainfall thresholds and the analysis of infrasound signals to develop reliable EWSs for debris flows.
Comparison of heliosphere models with IBEX-Lo observations of Energetic Neutral Atoms at 50 eV - 2 keV energy
Authors: Galli André , Baliukin Igor I. , Kornbleuth Marc , Fuselier Stephen A. , Sokół Justyna M. , Opher Merav
Published: February 2023

The Interstellar Boundary Explorer (IBEX) is a NASA satellite in Earth’s orbit, observing both interstellar neutral atoms entering the heliosphere and energetic neutral atoms (ENAs) from the interstellar boundaries from roughly 10 eV to 6 keV. IBEX consists of two ENA imagers: IBEX-Lo covers the low energy range from 10 eV to 2 keV, IBEX-Hi covers ENA energies between 500 eV and 6 keV (corresponding roughly to solar wind energy).ENA imaging is an indispensable tool in space physics. ENAs carry information on the plasma region where they were created that can be deciphered by analysis of the species, intensity, spatial distribution, and energy spectrum. The ENA intensity measured by a remote observer, such as IBEX, is a line of sight integral over potentially many different ion populations and local neutral atom densities. Thus, to derive properties of the heliosphere and of its plasma populations from such ENA measurements, they must be compared with the predictions of heliosphere models.The majority of ENA model comparisons with IBEX observations so far were restricted to IBEX-Hi data. In this study, we present the first comparison of IBEX-Lo data with heliosphere models over one full solar cycle (using the tabulated energy spectra in Galli et al. 2022, http://dx.doi.org/10.3847/1538-4365/ac69c9). We use heliosphere models developed at the Moscow University and Boston University in this study. The comparison concentrates on the energy spectra of heliospheric ENAs originating from regions in the sky (such as Voyager 1, Voyager 2, South Pole, North Pole, and heliosphere downwind direction) that are cardinal directions for the comparison of the ENA data and the global heliosphere models.This study is a part of the Research Team “Global Structure of the Heliosphere” within the SHIELD NASA DRIVE Science Center.
The positive effect of Nature-based Solutions for achieving the Sustainable Development Goals in Mediterranean agroecosystems: a meta-analysis
Authors: Rodrigues Miguel , Antunes Dias Luís Filipe , Carvalho Nunes João Pedro
Published: February 2023

The increasingly frequent impacts of climate change in the Mediterranean region challenge the resilience and sustainability of the region's agroecosystems. In this context, Nature-based Solutions (NbS) emerge as a sustainable strategy to address climate change adaptation and mitigation. Extensive literature focuses on the analysis of NbS to address this problem, although no analysis discriminates against the individual and combined effect of NbS in agroecosystems. In this work, we capitalize on state-of-the-art results and present a random-effects meta-analysis of NbS. Our analysis focuses on a cohort of 80 NbS for agricultural land management, such as conservation tillage practices, soil-improving cropping systems, organic amendments and fertilizers, and landscape solutions. We used response ratios as effect sizes to determine the most suitable NbS for improving soil health. We built a database with field-scale data from 70 published case studies comparing NbS and conventional agricultural management practices in agroecosystems in 12 countries with a Mediterranean climate. Our analysis results from a literature selection of 988 scientific articles published from 2019 to 2022. We have analyzed the combined effect that NbS have on soil's ability to retain water, organic matter, and carbon and to reduce soil loss. To further understand the influence of abiotic factors, we also analyze the impact of precipitation, soil texture, and irrigation systems on the effects of NbS. These results shall contribute to leveraging climate change adaptation in Mediterranean agroecosystems, addressing land and water-related Sustainable Development Goals (SDGs).
Applicability evaluation of Spectral Band Adjustment Factor for Cross-Calibration using high resolution optical satellite
Authors: Kim NaYeon , Han Kyung-soo , Choi Sungwon , Seong Noh-hun , Jung Daeseong , Sim Suyoung , Woo Jongho
Published: February 2023

Currently, research such as time-series vegetation index analysis, disaster monitoring, and aerosol monitoring are being conducted using high-resolution optical satellites. However, since each high spatial resolution satellite has differences in the spectral response of the two sensors, there is a limit of time-series monitoring when using satellite data fusion. In this study, the Spectral Band Adjustment Factor (SBAF) was calculated for Sentinel-2A and Landsat-8, which are high-resolution satellites, and cross-calibration was performed. When combining data from two satellites, it is necessary to overcome the difference in radiometric sensor characteristics of each satellite. The bias due to the difference in the spectral response of the two satellites was corrected through an adjustment factor derived from the EO-1 Hyperion data. As a result of applying SBAF, the difference in value was within 5%. In the future, based on the results derived from this study, it is expected to make a great contribution to continuous monitoring and time series analysis of aerosols including PM2.5.※ This work was supported by the "Graduate school of Particulate matter specialization." of Korea Environmental Industry & Technology Institute grant funded by the Ministry of Environment, Republic of Korea.
The eWaterCycle platform for open and FAIR hydrological collaboration
Authors: Hut Rolf , Aerts Jerom , Wiersma Pau , Hoogelander Vincent , van de Giesen Nick , Drost Niels , Kalverla Peter , van Werkhoven Ben , Verhoeven Stefan , Alidoost Fakhereh (Sarah) , Vreede Barbara , Liu Yang
Published: February 2023

The eWaterCycle platform introduced in 2022 (https://doi.org/10.5194/gmd-15-5371-2022) provides hydrologists with an online platform to conduct numerical studies involving hydrological models. It allows hydrologists to work with each other's data and datasets directly from a webbrowser. The workflow of the experiment done is clearly visible, reproducible and easily adaptable because of how eWaterCycle separates the model (the algorithm) used from the experiment done with the model. eWaterCycle is designed such that research conducted on the platform is ‘FAIR by design’. Using eWaterCycle, studies can be done in less time, more transparently and by more junior members of the hydrological community than was possible a few years ago. In this presentation, we will explain the capabilities of the eWaterCycle platform and show them by describing recently (published) works of MSc and PhD members of our team, including a model coupling study, a large sample hydrology study and a climate impact assessment study.
Evaluating the Drought-Monitoring Utility of GPM and TRMM Precipitation Products over Mainland China
Authors: Cheng Shuai
Published: February 2023

The purpose of this study was to evaluate the applicability of medium and long-term satellite rainfall estimation (SRE) precipitation products for drought monitoring over mainland China. Four medium and long-term (19 a) SREs, i.e., the Tropical Rainfall Measuring Mission (TRMM) Multi-Satellite Precipitation Analysis (TMPA) 3B42V7, the Integrated Multi-satellite Retrievals for Global Precipitation Measurement V06 post-real time Final Run precipitation products (IMF6), Global Rainfall Map in Near-real-time Gauge-calibrated Rainfall Product (GSMaP_Gauge_NRT) for product version 6 (GNRT6) and gauge-adjusted Global Satellite Mapping of Precipitation V6 (GGA6) were considered. The accuracy of the four SREs was first evaluated against ground observation precipitation data. The Standardized Precipitation Evapotranspiration Index (SPEI) based on four SREs was then compared at multiple temporal and spatial scales. Finally, four typical drought influenced regions, i.e., the Northeast China Plain (NEC), Huang-Huai-Hai Plain (3HP), Yunnan– Guizhou Plateau (YGP) and South China (SC) were chosen as examples to analyze the ability of four SREs to capture the temporal and spatial changes of typical drought events. The results show that compared with GNRT6, the precipitation estimated by GGA6, IMF6 and 3B42V7 are in better agreement with the ground observation results. In the evaluation using SPEI, the four SREs performed well in eastern China but have large uncertainty in western China. GGA6 and IMF6 perform superior to GNRT6 and 3B42V7 in estimating SPEI and identifying typical drought events and behave almost the same. In general, GPM precipitation products have great potential to substitute TRMM precipitation products for drought monitoring. Both GGA6 and IMF6 are suitable for historical drought analysis. Due to the shorter time latency of data release and good performance in the eastern part of mainland China, GNRT6 and GGA6 might play a role for near real-time drought monitoring in the area. The results of this research will provide reference for the application of the SREs for drought monitoring in the GPM era.
Aseismic creep and coseismic dislocation at an active fault in volcanic area: the case of Ischia Island
Authors: Carlino Stefano , Pino Nicola Alessandro , Beccaro Lisa , De Martino Prospero
Published: February 2023

Understanding the fault dynamics in volcanic areas is not a simple task, mainly due to both the heterogeneity of volcanic structures and the local stress distribution. The presence of high temperature-high pressure geothermal fluids and relative high strain rates, and the occurrence of viscous processes in the deeper part of the volcano further contribute to generate complex patterns of strain load and release, possibly with aseismic creep and differential movements along the faults.We present the case of an active fault located Casamicciola Terme town – in northern area of the volcanic caldera of Ischia Island (Southern Italy) – where repeated destructive earthquakes occurred at least since 1769, even causing thousands of victims in a single event, with the last one striking in 2017. To assess a possible mechanism leading to the activation of the Ischia main seismogenic fault, its cyclic nature and the related hazard, we performed a joined analysis of the ground vertical movements, obtained from cGPS (2001-present), DInSAR (2015-2018) time-series, and levelling data of the island (1987-2010). The geodetic data indicate that Casamicciola seismogenic fault is characterized by a complex dynamic, with some pre- and post-seismic aseismic dislocation, along sectors that move differentially, in response to the long-term subsidence of the island. Based on the ground deformation rate and on the distribution of degassing areas, we speculate that fluid pressure variations may have a major role in modulating the apparent non-stationarity of the Ischia stronger earthquakes. Furthermore, we suggest that a punctual monitoring of the distribution in space and time of the aseismic creep could provide clues on the state of strain of the seismogenic fault.
Experiences with an Enhanced Thermal Response Test (ETRT) with high groundwater flow
Authors: Albers Anna , Steger Hagen , Zorn Roman , Blum Philipp
Published: February 2023

With an enhanced thermal response test (ETRT) depth-specific effective thermal conductivities can be determined. For this, a correct determination of the specific heat load is crucial. With an ETRT the heat is injected along the depth of the borehole heat exchanger (BHE) by applying a defined voltage to an electrically conductive cable. Hereby, an uniform specific heat load along the entire length of the cable is assumed. However, the electrical resistance of the heating cable and therefore the specific heat load depend on temperature. In this study, an ETRT is conducted at a study site with high groundwater flow. The results are critically evaluated with regard to the specific heat load and depth-specific effective thermal conductivities. We show an inaccuracy of 12 % in the determination of effective thermal conductivities when assuming constant electrical resistance of the heating cable with time. When using temperature measurements from distributed temperature sensing (DTS) to adjust the specific heat load along the length of the heating cable, variations of the specific heat load along the BHE in the order of 3 % are observed. Depth-specific effective thermal conductivities are evaluated ranging between 3.3 W m-1 K-1 and 12 W m-1 K-1. For 60 % of the evaluated depth-intervals the results of the infinite line source (ILS) forward model do not converge according to the criterion of Δλeff/λeff < 0.05/20h. These depth intervals are characterised by high groundwater velocities (> 0.6 m d-1) and a temperature increase for the evaluation with linear regression of ΔT < 0.6 K. From our results, we provide recommendations for the determination and adjustment of the specific heat load during an ETRT to account for temporal and spatial variations. Furthermore, we emphasise the need for higher specific heat loads in groundwater influenced depth intervals and elaborate difficulties associated with the increase of the specific heat load and the corresponding temperature increase along the heating cable.
Urban groundwater fauna - natural or anthropogenically influenced?
Authors: Koch Fabien , Menberg Kathrin , Schweikert Svenja , Hengel Jessica , Spengler Cornelia , Hahn Hans Jürgen , Blum Philipp
Published: February 2023

Climate change and anthropogenic activities cause multiple changes in groundwater systems. Particularly, these processes lead to an increase in groundwater temperature under densely populated urban areas. While physico-chemical effects have been widely studied, the consequences for groundwater ecosystems are scarcely understood. However, a thorough understanding of how this sensitive ecosystem responds to various stressors, such as temperature, in urban environments is critical for a sustainable resource management.Thus, the aim of this study is to provide an assessment of the groundwater fauna in and around the city of Karlsruhe, Germany. We examine the ecological status of an urban aquifer by analysing fauna and physico-chemical parameters in 39 groundwater monitoring wells between 2011 and 2022. For classification, we apply the groundwater ecosystem status index (GESI), in which a threshold of more than 70% of crustaceans and less than 20% of oligochaetes serves as an indication for very good and good ecological conditions. Our study reveals that only 35% of the wells in the residential, commercial and industrial areas, and 50% of wells in a natural forest area fulfil these criteria and can be classified as natural and unstressed groundwater habitats in 2011-2014. In 2022, however, all wells in the forest area show a very good or good ecological status, irrespective of changes in diversity and number of individuals. Repeated measurements in 2022 also show significant changes in groundwater fauna with only slight changes in the physico-chemical parameters over time. A significantly decreasing number of individuals per well together with a decreasing biodiversity both in the forest and urban areas is observed.Overall, no clear spatial patterns in the ecological status are found with respect to land use and other anthropogenic impacts, such as groundwater temperatures. Nevertheless, we observe noticeable differences in the spatial distribution of groundwater species in combination with abiotic groundwater characteristics, such as groundwater temperature and geological settings. Monitoring wells in forest areas are characterized by lower groundwater temperatures, lower nitrate concentrations, and higher dissolved oxygen concentrations, indicating a link between abiotic groundwater characteristics and land use. In addition, these monitoring wells contain larger numbers of amphipods, which are considered as indicators of healthy ecosystems.The results of our study reveal heterogeneous and time-varying conditions in urban and natural groundwater as a habitat, which do not allow a clear assessment of the ecological status with existing assessment approaches. In the future, additional indicators, such as groundwater temperature, local geology, presence of indicator species, delineation of site-specific characteristics and natural reference conditions, should be therefore also considered in ecological groundwater assessments.
The effect of dynamic hydro(geo)logical boundary conditions on redox-zoning in high-energy subterranean estuaries
Authors: Greskowiak Janek , Seibert Stephan , Post Vincent , Massmann Gudrun
Published: February 2023

Subterranean estuaries (STE) below beaches are biogeochemical reactors that modify the composition of fresh meteoric groundwater and recirculating seawater before they enter the ocean via submarine groundwater discharge (SGD), which can affect coastal ecosystems. Thereby, prevailing redox conditions have a major impact on the concentrations and mass fluxes of water constituents, e.g., nutrients, metals and organic molecules within the STE. Due to the transient nature of the flow and transport within STEs as well as the variable hydrogeochemical boundary conditions, redox zoning in the STE is likely highly dynamic. Elucidating the factors that affect redox zoning and its dynamics is essential for the interpretation and understanding of hydrogeochemical data and the prediction of coastal solute fluxes. In the present study we investigated the individual and combined effects of storm floods, seasonal changes of temperatures and groundwater recharge rates, as well as beach morphodynamics on the redox behavior, i.e., redox zoning in the STE in a generic modelling approach. A 2D cross-shore density-dependent flow and reactive transport model was set up for this purpose, mimicking a beach aquifer exposed to high-energy conditions due to high tides, waves and storm floods. The results of this study show that redox dynamics can occur well down to a depth of 20 m. Morphodynamics were shown to be the most important factor for redox zoning in the STE. For cases where morphodynamics are less pronounced, e.g., at low-energy sites, storm floods and the seasonal temperature changes may be dominating. Seasonal changes in meteoric groundwater recharge rates seem to be least relevant for the redox dynamics in STEs. The results of the present study increase the understanding of STEs as biogeochemical reactors.
Which is the role of post-fire SOC erosion in the C cycle?
Authors: Girona-García Antonio , Santín Cristina , Vieira Diana , Doerr Stefan
Published: February 2023

Wildfires burn on average 448 million hectares globally every year, releasing around 2.2 Pg of carbon (C) into the atmosphere [1, 2]. The net effect of wildfires in the C cycle goes, however, beyond emissions and involves many other interacting processes. Among those, there is a significant knowledge gap on the role of post-fire soil organic carbon (SOC) erosion as a carbon sink mechanism.Post-fire erosive response is greatly enhanced by the direct and indirect effects of wildfires on soil and vegetation, such as the loss of protective cover and soil structure or the development of a water-repellent layer [3]. In addition, biomass and soil organic matter undergo quantitative and qualitative changes during wildfires, such as the formation of pyrogenic carbon, highly resistant to degradation. The resulting PyC and non-PyC carbon fractions, with contrasting physical properties and chemical stability, will be differently redistributed and mineralized during the erosion process [4]. Ultimately, post-fire SOC erosion will act as a carbon sink when the post-fire burial and stabilization of eroded carbon, together with the recovery of net primary production and soil organic carbon content, exceed the SOC losses during its post-fire transport [5]. All these processes have been scarcely investigated and poorly quantified to the date. In this presentation, we will provide new insights into this potential C sink mechanism, critically reviewing the state of the art and highlighting key research gaps.References[1] Boschetti et al., 2021. Global Wildfire Information System (GWIS). https://gwis.jrc.ec.europa.eu/apps/country.profile/downloads[2] Randerson et al., 2012. J Geophys Res. https://doi.org/10.1029/2012JG002128[3] Shakesby & Doerr, 2006. Earth-Sci Revs. https://doi.org/10.1016/j.earscirev.2005.10.006[4] Doetterl et al., 2016. Earth-Sci Revs. https://doi.org/10.1016/j.earscirev.2015.12.005[5] Santín et al., 2015. Glob Change Biol. https://doi.org/10.1111/gcb.128
Comparison of real-time NMVOCs measurements using PTR-TOF-MS in two cities of IGB region, India: Sources identification and influence on SOA formation
Authors: Jain Vaishali , Tripathi Sachchida N. , Tripathi Nidhi , Gupta Mansi , Sahu Lokesh K. , Murari Vishnu , Gaddamidi Sreenivas , Shukla Ashutosh K. , Prevot Andre S.H.
Published: February 2023

Non-methane volatile organic compounds (NMVOCs) are emitted from various anthropogenic and biogenic sources. They act as precursors for the formation of tropospheric ozone and secondary organic aerosols (SOA) in the presence of sunlight and oxidizing radicals (OH, Cl, NO3). The measurements of NMVOCs are essential to understand the formation of new gas-to-particle aerosols, leading to high air pollution episodes. The Indo-Gangetic Basin (IGB) of India, one of the world’s most polluted areas, has been experiencing high aerosols and NMVOCs loadings throughout the year. Delhi and Lucknow are the two main cities in the IGB region selected for the study. The main aim of this study is to compare the contributions of different source factors to NMVOCs concentrations and their role in SOA formation. A proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS) was deployed to perform real-time chemical characterisation of NMVOCs during two different campaigns in Delhi (2019) and Lucknow (2020-2021), respectively. The High-resolution Time of Flight Mass Spectrometer (HR-ToF-MS), Aethalometer and other instruments were also deployed at both sites. A receptor modelling approach, positive matrix factorisation (PMF), was used with a robust multilinear engine (ME-2) for source apportionment analysis. The present study is a novel attempt to perform PMF over mass spectra of ~90 and ~170 NMVOCs in Delhi and Lucknow, respectively, for different seasons. Their associations with secondary organic aerosol formation using SOA yields were also analyzed. For Delhi, 8-factor solution was selected and resolved into two traffic-related factors: solid-fuel combustions (SFC), secondary VOCs (SVOCs), biogenic factor and solvent-use factor based on statistical parameters. Similarly, for Lucknow, a 6-factor solution was selected with traffic, 2 SVOC factors, 2 SFC factors and one volatile chemical products-related factor. The traffic factor has the presence of aromatics, non-aromatics and oxygenates, while the biogenic factor is marked by isoprene and its fragment (methyl vinyl ketone). The first, second, and third-order oxygenates show peaks in the SVOCs factor, while phenols, furans, and n-containing compounds are found in the SFC factor. It is observed that vehicular emissions (30%) contributed highest to NMVOCs concentrations in Delhi, while the SFC (28%) was a prominent factor in Lucknow. Interestingly, SFC factors contribute the highest to SOA formation at both cities. It is inferred that the agricultural residue burning episodes in neighbouring states, trash burning and solid fuel burning for cooking within and around the cities contributed to the emissions of NMVOCs and the formation of SOA during winter and post-monsoon periods.
Performance of Low-cost GNSS/INS Receivers and Smartphone GNSS Positioning in Pedestrian Applications
Authors: Halaj Marek , Kacmarik Michal
Published: February 2023

In recent years, there has been a significant advancement in the field of Global Navigation Satellite Systems (GNSS). The completion of newly built systems (Galileo, BeiDou) together with the modernisation of long-standing systems (GPS, GLONASS) has brought new signals and also new services to users. A significant technological advance has also been achieved in the development and availability of low-cost devices enabling positioning and navigation based on GNSS alone or a combination of several technologies. The study focuses on testing GNSS receivers in smartphones and low-cost devices combining GNSS and inertial navigation. The aim was to address the current capabilities and the quality of positioning offered by these devices. The analyses were performed on test measurements performed in kinematic mode in an urban environment at walking speed. The aim was to make test measurements that are representative enough to reflect conditions commonly encountered in life. Advanced GNSS techniques were tested in both real-time and post-processing of the raw observations. Low-cost u-blox single and multi-frequency modules combining GNSS and inertial localization, as well as standard Samsung mobile phones were used. Impact of the GNSS (multi-)constellation on the quality of positioning was also evaluated, as some GNSS signals exhibit higher multipath resistance and a higher number of satellites can significantly help with positioning initialization and improve its accuracy.