bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial downscaling of rainfall fields using a multiple-point geostatistics-based approach
Authors: Zou Wenyue , Hu Guanghui , Wiersma Pau , Yin Shuiqing , Mariethoz Grégoire , Peleg Nadav
Published: February 2023

High-resolution gridded rainfall product at sub-daily and kilometer scales is required for many hydrological applications. In ungauged catchments, gridded rainfall data are often obtained through remote sensing, primarily satellites, whose spatial resolution is too coarse and requires to be downscaled to a finer resolution. The challenge is not only to downscale the rainfall intensity but also to downscale the spatial structure of rainfall fields, as both elements are essential for assessing the surface hydrological response. For this purpose, we further developed the stochastic multiple-point geostatistics (MPS) method, which enables the downscaling of long-term coarse-gridded rainfall using only a few years of high-resolution rainfall observations. We describe the methodology and demonstrate an application whereby long time series (1998-2019) of hourly CMORPH rainfall dataset are downscaled from 7 km to 1 km resolution based on training images from the 1-km CMPAS dataset available for a much shorter period (2015-2020), taking the area of Beijing as a case study. We show that the downscaled rainfall fields are following the expected spatial structure. Moreover, the downscaled rainfall intensities are consistent with station-based rainfall observations. And the heavy rainfall intensities at the 99th quantile match those expected due to the change in spatial scale and the application of an areal reduction factor. The results indicate that MPS preserves the spatial structure and downscales rainfall intensities well, especially for heavy rainfall, even if limited high-resolution training data is available. The proposed downscale approach can be applied to other rainfall datasets and in other regions.
Over 20 Years of Geoscience Information for Teachers (GIFT) Workshops at the European Geoscience Union General Assembly
Authors: Berenguer Jean Luc ,   EGU Committee on Education
Published: February 2023

Geoscience Information for Teachers (GIFT)  workshops are teacher enhancement workshops organized by the EGU Committee on Education and held in conjunction with the EGU annual General Assembly. The program focuses on a different general theme each year. Past themes have included, for example, “Energy and Sustainable Development”, “The Carbon Cycle”, “Mineral Resources”, “The Solar System And Beyond” and “The Mediterranean”. These workshops combine scientific presentations on current research in Earth and Space Sciences, given by prominent scientists attending EGU General Assemblies, with hands-on, inquiry-based activities that can be used by the teachers in their classrooms to explain related scientific principles or topics. Participating teachers are also invited to present their own classroom activities to their colleagues, regardless of the scientific topic. The main objective of these workshops is to communicate first-hand scientific information to teachers in primary and secondary schools, significantly shortening the time between discovery and textbook. The GIFT workshop provides the teachers with materials that can be directly incorporated into their classroom, as well as those of their colleagues at home institutions. In addition, the full immersion of science teachers in a truly scientific context (EGU General Assemblies) and the direct contact with leading geoscientists stimulates curiosity towards research that the teachers can transmit to their pupils. In addition to their scientific content, the GIFT workshops are of high societal value. The value of bringing teachers from many nations together includes the potential for networking and collaborations, the sharing of experiences and an awareness of science education as it is presented in other countries. Since 2003, the EGU GIFT workshops have brought together more than 700 teachers from more than 25 nations. At all previous EGU GIFT workshops teachers mingled with others from outside their own country and informally interacted with the scientists, providing a venue for rich dialogue for all participants. The dialogues often included ideas about learning, presentation of science content and curriculum. Programs and presentations of past GIFT workshops, with some available with Web streaming, are available at: https://www.egu.eu/education/gift/workshops/
Global streamflow modelling using process-informed machine learning
Authors: Magni Michele , Sutanudjaja Edwin H. , Shen Youchen , Karssenberg Derek
Published: February 2023

Hydrological models include errors when reproducing real-world observations, due to uncertainties in their components that inevitably propagate to the simulated variable. A large body of research in streamflow prediction blends statistical learning into the hydrological sciences, modelling river discharge using meteorological variables and catchment attributes as predictors of observed streamflow.We developed a novel hybrid framework that integrates information from the process-based global hydrological model PCR-GLOBWB to reduce prediction errors in streamflow simulations. Our statistical methodology employs simulated streamflow and state variables from PCR-GLOBWB as additional predictors of observed river discharge. These model outputs provide supplemental information that is effectively used in a random forest, trained on a global database of streamflow measurements, to improve estimates of simulated river discharge across the globe. PCR-GLOBWB was run for the years 1979-2019 at 30arcmin and daily resolution, and the simulated state variables were then aggregated to monthly time steps. A single random forest model was trained with these state variables, meteorological data and catchment attributes, as predictors of observed streamflow from 2286 stations worldwide.Results based on cross-validation show that the model is capable of discerning between a variety of hydro-climatic conditions and river flow dynamics, improving KGE of PCR-GLOBWB simulations at more than 80% of testing locations and increasing median KGE from -0.02 in uncalibrated runs to 0.52 after post-processing. Performance boosts are usually independent of availability of streamflow data at a particular station, thus making our method a potential candidate in addressing prediction in poorly gauged and ungauged basins.Further research is still needed to test the potential influence of additional predictors describing catchment and time-series behaviour. Cluster analysis is required to understand why the post-processing framework still performs poorly at some stations. For prediction purposes, future efforts should also be directed at testing the model at higher spatial resolutions globally, and at finer temporal resolutions.
Meteorology and mineral dust forecast variability during the CADDIWA campaign
Authors: Menut Laurent
Published: February 2023

As support to the operational field campaign of the CADDIWA field experiment, the coupled regional model WRF-CHIMERE in forecast mode during the summer 2021. The simulation domain covers West Africa and the East Atlantic and allows the modeling of dust emissions and their transport to the Atlantic. On this route, we find Cape Verde which was used as a base for measurements during the CADDIWA campaign. The forecast consists of meteorological variables and mineral dust concentrations on a horizontal grid with a resolution of 30 km and from the surface to 200 hPa. Each day, the simulation starts the day before (D-1) and up to 4 days ahead (D+4). For each day, we thus have 6 different calculations, with logically a better precision the closer we get to the analysis (D-1). This presentation will show a quantification of the variability of the forecast of mineral dust according to the modelled lead. This quantification will also be done according to the interactions between clouds, aerosols and radiation.
Improved simulation of extratropical North Atlantic atmosphere-ocean variability in HighResMIP models
Authors: Patrizio Casey , Athanasiadis Panos , Frankignoul Claude , Iovino Dorotea , Masina Simona , Famooss Paolini Luca , Gualdi Silvio
Published: February 2023

The simulated North Atlantic atmosphere­–ocean variability is assessed in a subset of models from HighResMIP that have either low-resolution (LR) or high-resolution (HR) in their atmosphere and ocean model components. In general, the LR models overestimate the low-frequency variability of subpolar sea-surface temperature (SST) anomalies and underestimate their correlation with the NAO compared to ERA5 reanalysis. These biases are substantially reduced in the HR models, and it is shown that the improvements are related to a reduction of intrinsic (non-NAO-driven) variability of the subpolar ocean circulation.To understand the mechanisms behind the overestimated intrinsic subpolar ocean variability in the LR models, a link is demonstrated between the biases in subpolar ocean variability and known biases in the mean state of the Labrador-Irminger seas. Supporting previous studies, the Labrador-Irminger seas are found to be too cold and too fresh in the LR models compared to observations from EN4 and the HR models. This causes upper-ocean density and hence convection anomalies in this region to be more salinity-controlled in the LR models versus more temperature-controlled in the HR models. It is hypothesized that this may cause the excessive subpolar ocean variability in the LR models by 1) promoting a positive feedback between subpolar upper-ocean salinity, convection and Atlantic Meridional Overturning Circulation (AMOC) anomalies, and 2) weakening the negative feedback between subpolar upper-ocean temperature, convection and AMOC anomalies that is apparent in the HR models. The results overall suggest that mean ocean biases play an important role in the simulation of the variability of the extratropical ocean.
Mobility and Burial of Munition Surrogates in the Inner Surf and Swash Zones
Authors: Puleo Jack A. , Idowu Temitope , Gangadharan Manoj , Chapman Emily
Published: February 2023

Unexploded ordnance (UXO) resulting from past military activity are present in coastal settings. Mobility of UXO, specifically in the inner surf and swash zones, constitutes a potential risk for the public. Mobility or exposure may increase under energetic events due to enhanced forcing or sediment erosion. Yet, the conditions leading to exposure, burial, or movement of UXO remain poorly understood. A large-scale laboratory wave flume (120 m x 5 m x 5 m) study at the Institut national de la recherche scientifique (INRS) in Quebec City, Canada was carried out from July 7 to September 23, 2022 to quantify surrogate UXO mobility and burial. An undistorted, scaled beach profile from Mantoloking, NJ, USA was constructed using 0.28 mm diameter sand. Eighteen stations were established at roughly 5 m intervals to collect hydrodynamic, sediment process, and morphology data and to quantify surrogate UXO behavior. Over 150 surrogates of varying bulk density were distributed throughout the flume. Waves were forced in 300-wave packets for each trial of a condition case. Cases used different wave heights, water levels, and wave periods. Preliminary results indicate berm erosion with increasing hydrodynamic energy. The dune only experienced erosion at the highest water levels. Surrogate UXO generally remained in place and buried partially or migrated offshore. Migration tendency and distance was a function of the surrogate density.
Estimation of amplitude noise reduction as a function of depth recorded by a deep vertical array (Northern Italy)
Authors: Rossi Camilla , Grigoli Francesco , Gasperini Paolo , Gandolfi Stefano , Cocorullo Chiara , Gukov Timur , Macini Paolo
Published: February 2023

To design an efficient seismic monitoring infrastructure, the characterization of the background seismic noise level of each potential seismic station installation site is one of the most important data-quality metrics used to evaluate the suitability of such sites to host the seismic network. The background seismic noise can be generated by different sources such as, ocean waves (microseisms), atmospheric turbolences (strong wind and storms), and anthropogenic activities. Such disturbances are characterized by specific frequency bands, time-occurrence (diurnal and seasonal variation), and site location (close to populated area or to the coasts). Reducing the effect of these noise sources is one of the main challenges to face for designing seismic monitoring networks and, more specifically, when selecting the hosting site of a seismic stations. A solution to attenuate the seismic noise effect is obtained by deploying seismic stations in boreholes. The noise level reduction with depth has been observed and studied by different authors, however a general law estimating the sufficient depth to gain is still missing. In this study, we analyse the continuous seismic noise level at S. Potito-Cotignola gas storage in the Po Valley (Northern Italy) recorded from January 2019 to December 2021 by a broadband (BB) seismic station at surface and a vertical array composed by 6-short period 3-components seismometers installed at depth ranging between 35 to 285 m in borehole. We aim to characterize the seismic noise by computing the amplitude noise reduction in terms of dB as a function of depth for different frequencies and the SNR by selecting three seismic events, with different epicentral distance and magnitude. Our results show that the noise level decreases with depth following a logarithmic empirical trend and the lowest magnitude event records the maximum SNR difference between the deepest sensor and the one at the surface. The estimated empirical relationships can be used to help the design microseismic monitoring networks in similar geological settings.
Climate impact storylines for assessing socio-economic responses to remote events
Authors: Van Den Hurk Bart ,   RECEIPT project team
Published: February 2023

Complex interactions involving climatic features, socio-economic vulnerability or responses, and long impact transmissions are associated with substantial uncertainty. Physical climate storylines are proposed as approach to explore complex impact transmission pathways and possible alternative unfolding of event cascades under future climate conditions. These storylines are particularly useful for climate risk assessment for complex domains, including event cascades crossing multiple disciplinary or geographical borders. For an effective role in climate risks assessments, practical guidelines are needed to consistently develop and interpret the storyline event analyses.This presentation elaborates on the suitability of physical climate storyline approaches involving climate event induced shocks propagating into societal impacts. It proposes a set of common elements to construct the event storylines. In addition, criteria for their application for climate risk assessment are given, referring to the need for storylines to be physically plausible, relevant for the specific context, and risk-informative.A number of examples of varying scope and complexity are presented, all involving the potential climate change impact on European socio-economic sectors induced by remote climate change features occurring far outside the geographical domain of the European mainland. The storyline examples illustrate the application of the proposed storyline components. It thereby contributes to the standardization of the design and application of event-based climate storyline approaches.
Exploring Macroplastic Transport and Retention Dynamics in Country-Wide River Networks
Authors: Mennekes David , Mellink Yvette , van Emmerik Tim , Nowack Bernd
Published: February 2023

Over the last years macroplastic has been increasingly monitored not only in oceans but also in freshwaters. Despite the ongoing discussion of linking plastic masses in rivers with masses in oceans, multiple studies showed a highly complex transport of plastic debris from in land-based sources towards the oceans. However, current modeling and monitoring studies mostly focused on specific processes in single rivers or used highly simplified approaches. While such studies may be helpful to identify the fate mechanisms, they are less suitable to predict macroplastic flows in a large river network on country-scale. The aim of our work was therefore to develop a macroplastic fate model for a whole country which was parameterized based on measurements in specific rivers. For the macroplastic modelling we considered four different states: (1) in suspension, (2) temporally stored (3) long term burial or accumulated and (4) removal / cleaning from in suspension or temporally stored masses. The model considers a high spatial resolution with river sections of few meters to kilometers in length which are connected to the overall river network. As input data we used macroplastic emissions predicted by a material flow analysis model on the same spatial resolution. The model was applied before to predict macroplastic masses on a river level.Using our model we found that the considered transport and fate processes for macroplastics must clearly differ from processes considered for microplastics. As possible influencing fate and transport factors we compared the influence of parameters such as sinuosity of rivers, the land use in close river distance, the discharge or impact of weirs with macroplastic removals. Each parameter was identified by other studies as potential factor for macroplastic retention. Here, we explore their influence on the output on a country-scale. We conclude that based on our modelling a high retention of macroplastics must occur within the system to match monitoring data with predicted macroplastic releases. While we assume that high amounts of macroplastics will be temporally stored until the next flooding event, it remains challenging to predict the long term in-situ accumulation. As a first step, we simulated different parameter settings to mimic "normal" discharge conditions in comparison with flooding events.Overall our results bring existing concepts and understanding in a wider context by coupling emission modelling with fate modeling and monitoring results from literature. Moreover, we are able to predict macroplastic masses in rivers and temporally stored in river banks and compare predicted values with first available measurements. Especially, predicting microplastic masses is of high importance for policy makers to manage plastic pollutions along riversides.
Deep-learning-based monthly precipitation forecast for Europe
Authors: Fuentes-Franco Ramon , Zimmermann Klaus
Published: February 2023

We implement deep neural networks to forecast monthly precipitation over Europe. This architecture conformed by several convolutional layers and fully connected layers uses four different variables (surface temperature, west-east wind at 200 hPa, precipitation and sea level pressure) coming from seven different operational forecast systems (1. ECCC 2. MeteoFrance  3. DWD  4. JMA 5. NCEP  6. ECMWF  7. CMCC). The neural network is trained using observations from E-OBS, a gridded land-only observational dataset covering the whole European continent. This convolutional neural network is trained using the period 1993-2012 and the validation period is 2013-2016, which is the range that is available for all operational forecast systems. Comparing with precipitation from observations we show that forecasted precipitation from this Deep-Learning model shows small biases in the whole European continent when forecasting monthly precipitation, especially over Sweden (with a small overestimation of less than 0.2 mm/day). With some higher negative biases over Southern Europe (<-1 mm/day). In turn, the representation of the mean precipitation over specific months and seasons was also assessed, showing that during the validation period this method is able to reproduce properly the spatial features of mean precipitation over Europe and its intensity.
Magnetospheric response to southward IMF turning: insights from global models and data analysis
Authors: Samsonov Andrey , Buzulukova Natalia , Milan Stephen , Sun Tianran , Branduardi-Raymont Graziella
Published: February 2023

We study the magnetospheric response to solar wind discontinuities with a southward interplanetary magnetic field (IMF) turning. We find two events characterized by a strong positive IMF Bz before the discontinuity and a strong negative Bz after the discontinuity. The magnetosphere stays in quiet conditions until the southward turning in both cases, then the dayside reconnection starts and the electromagnetic energy is accumulated in the magnetotail. We simulate these cases using several MHD models and compare numerical predictions of the global parameters such as the magnetopause standoff distance, open flux in the polar cap, auroral indices, and cross polar cap potential. We also make several runs of one model with different spatial resolutions and ionospheric conductivities. Summarizing this study, we discuss the differences between the MHD models and speculate about the reasons why one model is able to better predict observations than the other. We also discuss the reasons for different magnetospheric responses observed in two cases.
A nonlinear attachment-detachment model with adsorption hysteresis for suspension-colloidal transport
Authors: Bai Bing , Wu Haiyan , Bai Fan
Published: February 2023

With the increasing research on particles and biocolloids in terrestrial and aquatic systems, the transport and deposition of particles and biocolloids in porous media has become an important research topic. Based on the transport and deposition experiments of heavy metal pollutants and suspended-colloidal particles (SPs) in porous media, a nonlinear attachment-detachment model with adsorption hysteresis is proposed, which uses an adsorption function and scanning desorption isotherms to model the deposition effect of SPs. The reaction rate constant related to hysteretic characteristics essentially reflects the nonequilibrium hydrodynamic process during the transport of SPs. Static deposition tests and column experiments with pulse injection are used to calibrate the transport parameters. Column penetration experiments are performed under variable injection concentrations and seepage velocities. The results show that there is good agreement between simulated and experimental breakthrough curves (BTCs).This model shows that increasing or decreasing the seepage velocity results in substantial changes in the penetration concentration of SPs, which is closely related to the adsorption hysteresis and the deposition dynamics of SPs. When the injection concentration is increased, the effluent concentration clearly increases, which reflects a nonlinear deposition process. In contrast, with a decrease in the injection concentration, the release effect of the already deposited SPs prolongs the penetration process, which is also related to the hysteresis. Previously proposed linear attachment-detachment models probably result in an overestimation of the adsorption capacity of porous media.
Ecosystem Services Assessment in the Upper Catchment of Taiwan River Basins
Authors: Chin Wei-Cheng , Fan Chihhao
Published: February 2023

    This study used two hydrological models and three economic valuation models to evaluate the ecosystem services of three selected upper river catchment areas of Taiwan and compares the differences among the comprehensive ecosystem service values among them. The differences in the evaluation results could be the basis for developing the related national river catchment management policies. The hydrological balance and Thiessen polygons methods were used to assess soil water conservation in the investigated areas. The replacement cost, market price and surrogate market methods were employed to estimate the supplying, regulating, supporting and cultural service values.     Based on the survey of the public’s preference for ecosystem services conducted by the Council of Agriculture, Taiwan in 2020, the value of each individual ecosystem service is weighted and added together to represent the comprehensive ecosystem service values. The rank of the comprehensive ecosystem service values of the the three investigated catchment areas from high to low is the Dahan river in northern Taiwan, Dajia river in central Taiwan, and the Zengwen river in southern Taiwan.    In this study, we analyzed the calculated results and suggested possible future policy for three investigated rivers, helping to allocate limited resources to achieve best cost-effect results. According to the present study, the ecosystem service values of flood control and landslide prevention are the two most-valued indicators. However, these two service values estimated by replacement cost method was significantly higher for the Dahan river than the Dajia river and Zengwen river. In order to enhance the comprehensive ecosystem services and balance for the regional economic development, government policies should aim to increase the ecosystem service values of flood control and landslide prevention in the upper catchment areas of rivers for central and southern Taiwan.
Use of Sun-induced chlorophyll fluorescence in linear and non-linear light use efficiency models for remote estimation of plant photosynthesis
Authors: Cendrero-Mateo* Maria Pilar , Van Wittenberghe Shari , Laparra Valero , Rascher Uwe , Papuga Shirley A. , Ponce-Campos Guillermo , Moreno Jose F.
Published: February 2023

In this study, we address two relevant gaps when monitoring plant photosynthesis using remote sensing techniques; these are i) assess the seasonal trends and relationships observed between photosynthesis, optical vegetation indices, and chlorophyll fluorescence in crop systems and ii) evaluate the contribution of Sun-induced chlorophyll fluorescence (SIF) on linear and non-linear light-use efficiency-based (LUE) models for the remote estimation of plant photosynthesis. Coincident measurements of net plant photosynthesis (Anet), optical vegetation indices (i.e., Red edge index and photochemical reflectance index (PRI) among others), PSII operating efficiency (ΦPSII), and SIF were made at leaf level once a week in a wheat field under different nitrogen treatments. In LUE models, three key variables explain the seasonal variability of photosynthesis; these are the fraction of absorbed photosynthetically active radiation (fAPAR), LUE, and a correction factor related to meteorological conditions that limit LUE. In this study, the Red edge index was highly correlated with fAPAR (R2>0.70, p-value<0.05); however, neither PRI nor SIF were able to explain the seasonal changes of LUE (R2<0.10).  ΦPSII seasonal values (0.10 – 0.40) measured during the experiment indicated strong downregulation of the photosynthetic machinery. This explained why, in this study, SIF did not present a linear relationship with LUE. Our results confirmed that under stress conditions the non-photochemical quenching mechanisms (NPQ) control the energy dissipation pathway, breaking the linear relationship between photochemistry and fluorescence. Additionally, our study proved that changes in Anet could be better explained when optical vegetation indices, chlorophyll fluorescence, and meteorological conditions are combined in non-linear LUE-based models (R2 increased from 0.10 for the linear model to 0.60 for the non-linear model). These results confirmed the need to build non-linear models for the remote quantification of photosynthesis.
Large Lithospheric Seismic Velocity Variations Across the Northern Canadian Cordillera Imaged by Ambient Noise Tomography
Authors: Schutt Derek , Porritt Robert , Estève Clément , Audet Pascal , Gosselin Jeremy , Schaeffer Andrew , Aster Richard , Freymueller Jeffrey , Cubley Joel
Published: February 2023

Global-scale seismic velocity models of the Northern Canadian Cordillera show high velocities to the east of the Cordilleran deformation front and low velocities to the west.    This velocity contrast is consistent with other geophysical observables, such as regional seismological studies, that indicate a weak and thin lithosphere to the west that transitions quickly to a strong and thick craton-like lithosphere at the deformation front.    We present new results using data collected by the Mackenzie Mountains EarthScope Project, which included an ~875 km-long line of 40 broadband seismographs across the Cordillera and into the craton extending from roughly Skagway, Alaska to Great Bear Lake, Northwest Territories.    The 3-year overlap of this deployment with other broadband seismic stations in the region, most notably the EarthScope Transportable Array and the Yukon Northwest Seismic Network, allows for detailed 3-D Rayleigh wave ambient noise imaging of the upper lithosphere.    Results show large velocity variations west of the deformation front.   Notably, we image a 5% Vs low that extends from the upper crust to the asthenospheric mantle.   This plume-like structure, and associated weakening, may be a primary cause for the ongoing uplift of the Mackenzie Mountains at their unusually eastward location.   We also image a low velocity feature in the lower crust extending to the west of the deformation front, which may facilitate eastward crustal translation along a large-scale (~800 km) decollement system driven by the Yakutat indentor consistent with the orogenic float hypothesis of Mazzotti and Hyndman (2002).    We also note strong lithosphere-scale lateral heterogeneity suggesting that 3-D effects are important in focusing deformation in the Mackenzie Mountain area.
Plane curves on the Earth’s triaxial ellipsoid
Authors: Filaretou Christina , Panou Georgios
Published: February 2023

In several geodetic studies, the triaxiality of the Earth has been proven beyond a reasonable doubt, thus a triaxial ellipsoid is a better approximation and a more natural reference surface. As opposed to geodesics, plane curves on this surface are relatively easy to solve. These curves are produced by the intersection of a central ellipsoid and a plane and it is proved that they are in general ellipses. Therefore, we study the problems of the computation of an arc length of an ellipse and the determination of a point after a given length on an ellipse, using either a numerical or an approximate analytical method. Also, all the required transformations of the coordinates from the plane of the section to 3D space and conversely, are given. Subsequently, five types of planes of the ellipsoidal sections are determined: the central section, two normal sections, and two mean normal sections. Furthermore, the algorithms that solve the direct and inverse problems for these plane curves on a triaxial ellipsoid are described. Extended numerical experiments demonstrate the workability of the presented method which can also be applied to other celestial bodies. All developments in the literature assume the presence of an oblate spheroid and include an iterative scheme to solve the aforementioned problems. Alternatively, in this work, we provide the most general solutions to these problems applicable and for an oblate spheroid and all types of sections, without iterations.
Analytical developments at the Potsdam SIMS user facility and the metrological limits on in situ isotope ratio data
Authors: Scicchitano Maria Rosa , Wiedenbeck Michael , Couffignal Frederic , Glynn Sarah , Wudarska Alicja , Trumbull Robert , Rocholl Alexander
Published: February 2023

The German Research Centre for Geosciences (GFZ) in Potsdam hosts a CAMECA 1280-HR large geometry secondary ion mass spectrometer (SIMS) with a web-based user node at the University of the Witwatersrand, South Africa. A major theme of our facility is high-precision, high-accuracy, high-spatial resolution analyses of light isotope ratios in a variety of natural and experimental materials.The latest analytical developments from the GFZ SIMS laboratory focus on the development, assessment and use of new reference materials for stable isotope analysis. Particularly for oxygen, our repeatability from 15-µm diameter domains is now typically better than ±0.15‰ (1s). However, the total uncertainty on such analyses is commonly larger because of significant differences (in some cases more than one ‰) among the isotope ratios of reference materials reported by multiple, highly regarded gas source mass spectrometry laboratories. This issue of interlaboratory bias during reference material characterization inevitably impacts all in situ data employing such materials and must be duly considered.
Implications for engineering design of shorter more extreme rainfalls and increased flood variability
Authors: Wasko Conrad , Ho Michelle , Nathan Rory , Sharma Ashish , Dykman Caleb , Vogel Elisabeth
Published: February 2023

Increases in extreme rainfall intensities as a result of climate change pose a great risk due to the possible increases in pluvial flooding. But evidence is emerging that the observed increases in extreme rainfall are not resulting in universal increases in flooding. Here, we begin by presenting historical evidence for changes in extreme rainfalls and floods discussing the underlying mechanisms for the changes, before examining the implications of climate change projections on engineering design.Extreme rainfall is intensifying universally across the globe with more extreme events experiencing larger degrees of intensification. Simultaneously, and somewhat paradoxically, the magnitude of frequent floods (those expected to occur on average once per year) are in general decreasing, particularly in the tropical and arid regions of the world. We suggest this is likely due to the dominance of drying antecedent soil moisture conditions and shorter storm durations at higher temperatures offsetting any increases in rainfall intensity. However, for rare magnitude floods (those expected, on average, to occur less than once every twenty years) the increase in rainfall appears to outweigh any decrease in soil moisture or change in the temporal pattern of the storm.Climate model projections, downscaled through a continental scale water balance model and locally calibrated rainfall-runoff models, show that future projections of flood responses follow historical trends – with the rarer the flood, the more likely it is to be increasing. To deepen our understanding, we focus our analysis on event runoff coefficients as an indicator of future runoff changes. Across Australia we find runoff coefficients are projected to decrease, that is, reduced runoff resulting from the same amount of rainfall. These results indicate drier conditions and a compounding of the reduced average rainfall and drier conditions already being experiences in many arid parts of the world.With these historical changes and projections in mind we conclude with some insights and implications on how best to incorporate the additional uncertainty due to climate change when estimating floods for planning and design purposes. As floods constitute a large portion of the inflows into reservoirs, we suggest that future water resources planning will need to account for reduced runoff yields. To assess the potential impacts of future climate change for planning and design purposes we need to consider how changes to rainfall intensity vary with both storm duration and storm rarity, as well as how antecedent conditions influence the proportion of rainfall that appears as runoff. There remains significant work in adapting our current flood guidance to reflect these historical and projected changes.
Accumulation of atmospheric metal and nitrogen deposition in mosses 1990-2020, comparison with emission data and tree canopy drip effects
Authors: Schröder Winfried , Nickel Stefan , Dreyer Annekatrin , Völksen Barbara
Published: February 2023

Mosses are suitable for recording the bioaccumulation of atmospheric deposition over large areas at many sites. In Europe, such monitoring has been carried out every five years since 1990. Mosses have been collected and chemically analysed for metals (since 1990), nitrogen (since 2005), persistent organic pollutants (since 2010) and microplastics (2020). The aims of this study were: 1. To analyse the temporal trends of metal and nitrogen accumulation in mosses between 1990 or 2005, respectively, and 2020 in Germany; 2. To compare the accumulation trends with emission data; and 3. To determine the effect of tree canopy drip on metal and nitrogen accumulation in mosses. For the temporal trend analysis, the minimum sample number required for a reliable estimation of arithmetic mean values and statistical parameters based on it was calculated. It was only achieved for nitrogen, but not for metals. Therefore, the temporal trends of bioaccumulation of metals and nitrogen were calculated on the basis of median values. For the analyses of tree canopy effects on elements accumulation in mosses, 14 vegetation structure measures were used, which together with 80 other descriptors characterise each moss collection site and its environment. The comparison of the data obtained during the first monitoring campaign with those of the 2020 survey showed a significant decrease in metals bioaccumulation. However, in contrast to the emission data, an increase in accumulation of some metals was observed between 2000 and 2005 and of all metals from 2015 to 2020. Trends in Germany-wide nitrogen medians over the last three campaigns (2005, 2015, 2020) show that nitrogen medians decreased by -2% between 2005 and 2015 and increased by +8% between 2015 and 2020. These differences are not significant and do not match the emission trends. Inferential statistics confirmed significantly higher metal and nitrogen accumulation in mosses collected under tree canopies compared to adjacent open areas. Measured concentrations of metals and nitrogen were significantly higher under tree canopies than outside of them, by 18-150 %.Keywords: Bioaccumulation; regression analysis; trend analysis
On the several shearing evidences developed in the Yangsan Fault, Korea
Authors: Ryoo Chung-Ryul
Published: February 2023

In large fault zone, various contractional and extensional structures accommodate horizontal shortening and extension in response to differential plate movements related to the Earth’s rotation. In this study, it was conducted a structural analysis of the Yangsan Fault, developed in the southeast Korea. The fault is about 200 Km long in land and has a general NNE-trend, cutting not only the Cretaceous rocks but also the Quaternary layers. We studied several main fault zones along Yangsan Fault. Here, we discuss some kinematic evidences and characteristics developed in the main fault zones of the Yangsan Fault, Korea. In the core of the Yangsan Fault Zone, fault-bounded sheets or blocks are horizontally rotated, duplexed and folded. From the kinematics of the sheet-bounding faults and intra-sheet minor folds, we suggest some evolutionary models of the Yangsan Fault Zone in which repeated fault-related rotation, dragging and folding are occurred.
Dating a world-unique Pacific ruin: Nan Madol
Authors: Shen Chuuan-Chou (River) , Beardsley Felicia , Gong Shou-Yeh , Kataoka Osamu , Yoneda Minoru , Yokoyama Yusuke , Jiang Leilei , Lin Albert Yu-Min , Fox James , Barnabas Jason , Kohler Gus , Richards Zoe T. , Hobbs Jean-Paul A.
Published: February 2023

Great Holocene civilizations on Pacific islands were created by Homo sapiens. However, most of the construction histories remain uncertain due to the lack of developed writing system and the limitation of dating techniques. Nan Madol (0.7 km in width and 1.5 km in length), an abandoned city called the “Venice of the Pacific” with over 100 artificial islets, is located on the southeastern coast of island Pohnpei in Micronesia. This world-unique ruin, inscribed onto UNESCO’s World Heritage List in 2016, was built with basalt megaliths and scleractinian coral cobbles. Oral histories and previous charcoal 14C ages suggested that the main construction of Nan Madol of Pohnpei could begin in the 13th or 14th century and ceased at the 16th or 17th century, associated with the rise and fall of the Saudeleur Dynasty. However, after 150 years or more of studies, the timing of construction and the dynasty, and the probable influence of environmental factors, remain unresolved. High-precision U-Th dating techniques, developed at the High-Precision Mass Spectrometry and Environment Change Laboratory (HISPEC), Department of Geosciences, National Taiwan University, were used to date the selected pristine coral infills and reveal the construction time of the two ruins. With over 150 coral ages determined, results show a peak of construction activity during the middle 11th century could be related to the rise of the Saudeleur Dynasty. In the early 15th century, construction activities ceased, associated with the dynasty’s downfall. Our study shows that Nan Madol construction and the rise and fall of the dynasty occurred 2-3 centuries earlier than previously estimated. Moreover, the entire development was dominated by El Niño-Southern Oscillation variability and tectonic-related sea level rise.
What explains low young water fractions at high elevations?
Authors: Gentile Alessio , Canone Davide , Ceperley Natalie , Gisolo Davide , Previati Maurizio , Zuecco Giulia , Schaefli Bettina , Ferraris Stefano
Published: February 2023

The concept of young water fraction, introduced by Kirchner (2016) and defined as the fraction of streamflow that was stored less than about 2-3 months in the catchment, is increasingly used in catchment intercomparisons studies to understand and conceptualize the hydrological processes governing the catchment's functioning. However, the development of perceptual models is not always as straightforward as it may seem. Past works have shown that high mountainous catchments worldwide reveal small young water fractions. These low young water fractions at high elevations have been explained by different hydrological processes, including deeper vertical infiltration promoted by the presence of both fractured bedrock and freely draining soils (e.g., luvisols and cambisols) and long groundwater flow paths driven by the topographic roughness. But, a harmonious explanation of how the relevant mechanisms in mountainous catchments lead to low young water fractions at high elevations is missing.Using a data set composed of 27 study catchments, located both in Switzerland and in Italy (of which 22 are from the previous work of von Freyberg et al., 2018), we explore both the drivers and the conceptualization of the processes that potentially clarify this surprising result. We assume that this lowering can be explained by groundwater storage potential and the interplay of the seasonal dominance of hydrological processes. For groundwater storage potential we use the proportion of catchment area covered by Quaternary deposits (a parameter that is readily available for the studied catchments). For the interplay of seasonal processes, we use the length of the low-flow period as a measure for the duration of the groundwater (in terms of age, old water) dominated recession period.Our results suggest that the length of the low-flow period is clearly the main driver of low young water fractions at high elevation. Here, the long winter period, characterised by absence of liquid water input and hence by a low-flow regime, promotes a progressive emptying of the groundwater storage. Even during summer, recent snowmelt and rainfall that transit through the subsurface push out old groundwater into the stream, as reflected by high proportions of baseflow also during high-flow periods. However, during summer, the relative share of old water remains lower than during winter and accordingly, the longer the winter period (with very low young water fractions), the lower the annual young water fraction. Quaternary deposits could play a role in reducing young water fractions via their capacity to store groundwater, but further detailed geological information would be necessary for a complete picture about the role of geology.
A Measurement Campaign in Thessaloniki, Greece, to Detect and Estimate Local Greenhouse Gas Emissions
Authors: Feld Lena , Schmid Pablo , Hase Frank , Ruhnke Roland , Mermigkas Marios , Balis Dimitrios , Braesicke Peter
Published: February 2023

The reduction of carbon emissions is required to limit global warming. Thus, measurement-based methods to monitor the progress in reducing emissions are essential. A significant part of the global emissions is produced in urban areas where also industry is located. Here, we investigate the urban area of Thessaloniki to better understand the distribution of local greenhouse gas sources during October 2021 and the summer of 2022.We present results of a measurement campaign using a pair of Fourier-Transform Infrared (FTIR) Spectrometers of the type EM27/SUN developed by Bruker and KIT.The measurement campaign took part in the framework of the Collaborative Carbon Column Observing Network (COCCON). During the campaign the spectrometers were used in an up- downwind setup. One spectrometer was located in a central position of the city while the second instrument was transported to various locations at the boundaries of the city, selected according to the prevailing wind direction. Additionally, measurements to characterize the advected background variability were performed. Here, the spectrometers were arranged orthogonal to the prevailing wind direction to estimate the variability of the background concentrations of carbon dioxide and methane.In total, 30 days of measurements were collected, giving a comprehensive dataset to study the emissions of the city area. The measurements are interpreted using a box model to estimate the averaged emission area fluxes. We present results for both, carbon dioxide and methane, and discuss the temporal and spatial variability we encountered.In a next step, we aim to confront these measurements with simulation results with idealized tracer emission patterns using the ICON-ART modeling framework, a numerical weather forecast model developed and used operationally by the German Weather Service (DWD). The results from the box model introduced above will be used as a starting point to combine measurements and simulations. First simulations produced for this purpose will be shown.
A process-based model for fluvial valley width
Authors: Turowski Jens , Bufe Aaron , Tofelde Stefanie
Published: February 2023

The width of fluvial valley-floors is a key parameter to quantifying morphology in mountain regions. It is important in diverse fields including sedimentology, fluvial geomorphology, and archaeology. Valley-floor width has been argued to depend on climatic and tectonic conditions, on the hydraulics and hydrology of the river channel that forms the valley, and on sediment supply from the valley walls. Yet, so far, a physically-based model that can be used to predict valley width is lacking. Here, we derive such a model. As has been done before, we assume that valleys are formed by the erosion of the valley walls by a river migrating across the valley floor. We conceptualize river migration as a Poisson process, in which the river changes its direction stochastically, at a rate determined by hydraulic boundary conditions. This approach yields a characteristic timescale of migration into a particular direction. The valley width can then be determined by integrating the speed of migration over this timescale. We develop equations for the timescale and the migration speed and predict that an unconfined valley or channel belt width scales with the square of the flow depth of the river. We expand the model to arrive a single equation that also includes the effects of uplift and lateral hillslope sediment supply. Both of these effects lead to a decrease in valley width in comparison to the unconfined width. The model predicts that at low uplift rates, the valley width tends to the unconfined width, and at high uplift rates to the channel width, and connects these two limits by a logarithmic equation. As a consequence, valley width increases with increasing drainage area, with a scaling exponent that typically lies in the range between 0.4 and 0.8, but can also be lower or higher. Finally, we compare the model to three data sets of valleys in uplifted regions and show that it closely predicts the first order relationship between valley width and uplift rate.