bluuebunny/crossref_metadata_2025 huggingface dataset:
The Beast from the East - winter atmospheric blocking over Eastern Europe during the Late Holocene and its role in regional climate variability
Authors: Perşoiu Aurel , Ionita Monica
Published: March 2022

Several recent cold winters in North America and Western Europe has drawn attention on the possible increase in the frequency and/or intensity of extreme events in the mid-latitude Northern Hemisphere. Whether these could result form a strengthening or weakening of the circumpolar vortex and/or shift in the position of the North Atlantic storm track is still a matter of hot debate. A less known player in this conundrum is the dynamics of the Siberian High, one of the major semi–permanent and quasi–stationary weather systems in the Northern Hemisphere; active in winter and associated with dense and cold air masses over Asia and East Europe. The causes behind the variability of the of the Siberian High (strengthening and south and westwards expansion) are still poorly understood, yet important in the context of future climatic changes expected in the core area of its manifestation. In this context, we present here an overview of the present and past (~5000 years) dynamics of the Siberian High, based on 1) modern climate data from Asia and Eastern Europe and 2) proxy-based reconstructions of winter climatic conditions (temperature and precipitation amount). Our analysis starts with a instrumental-based investigation of the mechanisms behind the onset, strengthening and westward expansion of the high-pressure cell centered over North Asia. We further construct and test several hypotheses behind these mechanisms and test them by analyzing the dynamics of winter conditions during several episodes of particularly cold events in the Northern hemisphere (at 4.2 ka BP, 2.8 ka BP, 1.3 ka BP, 0.8-0.2 ka BP). We tentatively suggest that high insolation gradients between summer and winter in the high–latitudes of the Northern Hemisphere could result in the weakening of the polar vortex and increase in the meandering behavior of the jet that leads to an early onset of winter in North Asia. The expanding snow cover reinforces the strength of the Siberian High, leading to its expansion towards south and west and thus bringing colder conditions in West Asia and Europe. Future Arctic amplification could result in a higher frequency of similar behavior of the climate system, thus leading to more frequent and stronger cold spells across Europe.
Coherence-based GPR diffraction imaging and inversion
Authors: Bauer Alexander , Schwarz Benjamin , Gajewski Dirk
Published: March 2022

In both seismic and electromagnetic imaging the diffracted wavefield has gained importance in recent years. While seismic data is often acquired for a large range of different source-receiver offsets, ground-penetrating radar (GPR) acquisitions are mostly (near-) zero-offset. This characteristic inhibits the use of reflected waves for the estimation of depth velocities, which in turn increases the importance of a reliable imaging and characterization of the diffracted wavefield. In this study, we adapt a coherence-based workflow originally designed for seismic wavefields to ground-penetrating radar (GPR) data, which often exhibit similar wave propagation phenomena. The first step of the proposed workflow is the coherence-based imaging of the often predominant reflected wavefield, which in the second step is adaptively subtracted from the original data, resulting in an approximation of the diffracted wavefield. In the third step, we characterize the previously revealed diffracted wavefield by means of wavefront attributes, namely slopes and curvatures. In the fourth and final step, these wavefront attributes can be used for the estimation of depth velocities by means of wavefront tomography, an inversion scheme that provides both the localization of scatterers and a smooth velocity model of the subsurface. We demonstrate the wide applicability of the suggested workflow on two GPR field data examples provided by the USGS – one recorded in the aftermath of Hurricane Sandy on the shores of Long Beach Island, New Jersey, the other capturing the internal structure of Wolverine Glacier, Alaska.
Modeling the long-term leaching of PFAS in heterogeneous vadose zones
Authors: Guo Bo , Zeng Jicai
Published: March 2022

PFAS are emergent contaminants of which the fate and transport in the environment remain poorly understood. A growing body of site investigations have demonstrated that vadose zones serve as significant long-term sources of PFAS to contaminate groundwater. As surfactants, adsorption at air–water and solid–water interfaces in soils complicates the retention and leaching of PFAS. Recent modeling studies accounting for the PFAS-specific nonlinear and rate-limited adsorption processes predicted that the majority of long-chain PFAS remain in the shallow vadose zone decades after contamination ceases—in agreement with many field observations. However, some field investigations show that long-chain PFAS have migrated to tens to a hundred meters below ground surface in the vadose zone. These discrepancies may be attributed to model simplifications such as a homogeneous representation of the vadose zone. The other potentially critical process that has not been fully examined is how surfactant-induced flow (SIF) influences PFAS leaching in multidimensions.

We develop a new three-dimensional model incorporating the PFAS-specific flow and transport processes to quantify the impact of SIF and subsurface heterogeneities. Our simulations and analyses conclude that 1) SIF has a minimal impact on the long-term leaching of PFAS in the vadose zone, 2) preferential flow pathways generated by subsurface heterogeneities lead to early arrival and accelerated leaching of (especially long-chain) PFAS, 3) acceleration of PFAS leaching in high water content preferential pathways or perched water above capillary barriers is amplified compared to conventional contaminants due to the destruction of air–water interfaces, and 4) subsurface heterogeneities are among the primary sources of uncertainty for predicting PFAS leaching and retention in the vadose zone. In addition to the specific findings, this talk will also discuss more generally the challenges and opportunities that arise from understanding and quantifying PFAS leaching in heterogeneous vadose zones.
Degradation of mercury (Hg) signals on incipient weathering refines use of Hg as a volcanic paleoproxy
Authors: Park Junhee , Stein Holly , Georgiev Svetoslav , Hannah Judith
Published: March 2022

Perceived mercury (Hg) enrichments and elevated ratios of Hg to total organic carbon (Hg/TOC) in sedimentary rocks have often been linked to volcanism from large igneous provinces (LIPs) and mass extinctions, prompting the hypothesis that elevated Hg concentrations are a proxy for intense volcanism from LIPs.  However, primary Hg and TOC contents of sedimentary rocks can be altered by secondary processes, for example, intense weathering [1].  Before endorsing cause-and-effect between volcanic Hg emissions and biotic crises or mass extinctions, the magnitude of measured Hg and Hg/TOC anomalies in weathered outcrop samples must be compared to equivalent units in core samples, where the outcrop sample provides, in effect, a minimum concentration value.  

Here, we investigate the effects of incipient weathering on Hg contents and Hg/TOC ratios.  We quantify the behavior of Hg during incipient weathering by determining Hg concentrations in visually pristine black shales from outcrops of the Upper Permian Ravnefjeld Formation in East Greenland, comparing these data to equivalent intervals acquired from drill core taken from a plateau 7 km from the outcrop.  Directly correlative Upper Permian shales (drill core) from the mid-Norwegian shelf further enhance our comparison.  Using detailed geochemistry and principal component analysis (PCA), we characterize the main host phases of Hg and relate different Hg contents from pristine samples from East Greenland and the mid-Norwegian shelf to different Hg inputs during shale deposition.  Importantly, we show the vulnerability of Hg contents and Hg/TOC ratios to incipient weathering of fresh-appearing outcrops of organic-rich shale.  

Working with drill core rather than outcrop samples is essential to circumvent the problem, and to provide accurate Hg concentration data for primary events in the paleo-record.

[1] Charbonnier, G., Adatte, T., Föllmi, K.B., and Suan, G. (2020) Effect of intense weathering and postdepositional degradation of organic matter on Hg/TOC proxy in organic-rich sediments and its implications for deep-time investigations. Geochemistry, Geophysics, Geosystems, 21(2).

Funding – HS acknowledges the support of ACS-PRF award #59965-ND2 supporting AIRIE PhD student JP.  Drill cores were acquired from GEUS under Petromaks grant (NFR 180015/S30).  Colorado State University-Geosciences provides no funding for the personnel and operation of the AIRIE Program and its Re-Os laboratories. 
Particle tracking as a vulnerability assessment tool for drinking water production
Authors: Pryet Alexandre , Matran Pierre , Cousquer Yohann , Roubinet Delphine
Published: March 2022

The assimilation and prediction of concentration data is often impeded by the computation time of groundwater transport models based on the resolution of the advective-dispersive equation. This is unfortunate because such data is often rich in information and the prediction of concentration values is of great interest for decision making.  Particle tracking may be used as an efficient alternative under a series of simplifying assumptions, which are often reasonable at groundwater sinks. A rapid transport model allows the use of assimilation and optimization methods requiring many model calls.  We developed a Python package to facilitate the use of the USGS MODFLOW6 and MODPATH7 models to simulate the transfer of tracer or contaminant concentrations to a groundwater sink (typically a pumping well or a drain). The approach requires the identification of one or a series of sources of tracer/contaminant such as a contaminated stream or area in the model domain. The package handles particle seeding around the sink and estimation of the concentration of water withdrawn from the sinks. Both “strong” and “weak” sources can be considered. Concentrations are computed with a mixing law from the particle endpoints and velocities. We investigated the best practice to obtain robust derivatives with this approach, which is essential for all methods based on the linearized version of the model. We provide a step-by-step workflow from model construction to parameter estimation, linear uncertainty analysis, and chance-constraints optimization with the PEST suite. The interest and practical details of the approach are illustrated on a well field vulnerable to a stream, and a parametric analysis is provided in order to evaluate the impact of key numerical parameters on the presented results.
Linking lysimeter and field sensor data to investigate water flow in a heterogeneous setting at the SUPREHILL vadose zone observatory
Authors: Krevh Vedran , Defterdarović Jasmina , Han Luka , Filipović Lana , Kovač Zoran , Groh Jannis , He Hailong , Filipović Vilim
Published: March 2022

Direct measurements of water flow can provide valuable information that is not always attainable through sensors alone, however, combining methods is crucial for unlocking their full potential. Water flow monitoring is critical for the successful detection of pollutant fate in intensive agricultural production as a substantial amount of fertilizer and pesticide products are commonly used. Wick lysimeters are a common technique used for water flow measurements, where a quantity of drainage volume is measured over time. For mentioned purposes, passive wick lysimeters that maintain tension in soil by using an inert wicking material were employed in this study. This study presents a link between self-constructed passive wick lysimeters, volumetric water content sensors (TDR) and soil-water potential sensors used at the newly (2020) established SUPREHILL vadose zone observatory in Croatia, located on a hillslope vineyard. At the observatory, a network of lysimeters (x36) is installed throughout the hillslope and is accompanied by an extensive sensor network. The data from 2021 shows variability between lysimeters in regard to their position on the hillslope, as well as variability between its repetitions, suggesting the influence of soil heterogeneity at the observatory that possibly triggers preferential flow. Along with the data, a methodology for lysimeter installation and construction is presented.
Precipitation regridding – Impacts at global scale
Authors: Rajulapati Chandra Rupa , Papalexiou Simon Michael , Clark Martyn P. , Pomeroy John W.
Published: March 2022

Re-gridding considerably alters precipitation statistics. Despite this fact, regridding precipitation datasets is commonly performed for coupling or comparing different models/datasets. In general, several studies have highlighted the effects of regridding at regional scale. In this study, the effects of re-gridding precipitation are emphasized at a global scale using different regridding methods, size of the shifts and resolutions of the dataset. Substantial differences are noted at high quantiles and precipitation dry (or wet-dry frequency) is altered to a great extent. Specifically, a difference of 46 mm in high (0.95) quantiles and a reduction of 30% wet-dry frequency is noted. The differences increase with the size of the grid shift at higher quantiles and vice versa for low quantiles. As the grid resolution increases, the difference between original and regridded data declines, yet the shift size dominates for high quantiles for which the differences are higher. Spatially, large differences at high quantiles in tropical land regions, and at low quantiles in polar regions are noted. These impacts are approximately same for the three different (first order conservative, bilinear, and distance weighted averaging) regridding methods considered in this study. Overall, re-gridding should be performed with caution as it can alter the statistical properties of precipitation to a great extent and adds uncertainty to further analysis of using in any models or in combined precipitation products.
Reconstruction of the upstream solar wind at comet 67P
Authors: Nilsson Hans , Möslinger Anja , Williamson Hayley , Bergman Sofia , Stenberg Wieser Gabriella
Published: March 2022

 Rosetta followed comet 67P at heliocentric distances from 1.25 to 3.6 au. The solar wind was observed for much of this time, but significantly deflected and to some extent slowed down by the interaction with the coma. A method is derived to reconstruct the upstream solar wind from H+ and He2+ observations. The method is based on the assumption that the comet - solar wind interaction can be described by an electric potential that is the same for both H+ and He2+. The reonstructed speed is compared to estimates from the Tao model, as well as OMNI and Mars Express data propagated to the observation point. The reconstruction agrees well with the Tao model for most of the observations, in particular the statistical distribution of solar wind speed. The electrostatic potential relative to the upstream solar wind is derived and shows values from a few tens of V at large heliocentric distances to about 1 kV during solar events and close to perihelion. Reconstructed values of the solar wind for periods of high electrostatic potential are also in good agreement with propagated observations and model results. The Tao model captures some slowing down of high speed streams as compared to observations at Earth or Mars. At low solar wind speeds, below 400 km/s, agreement is better between our reconstruction and Mars observations than with the Tao model. The magnitude of the reconstructed electrostatic potential is a good measure of the slowing down of the solar wind at the observation point.
Empirical evidence of frequency-dependent directivity effects from small-to-moderate normal fault earthquakes in Central Italy
Authors: Colavitti Leonardo , Lanzano Giovanni , Sgobba Sara , Pacor Francesca , Gallovič František
Published: March 2022

Rupture source directivity and its potential frequency dependence remains an open question in seismology, especially for small-to-moderate earthquakes. 

In this research, we first calibrate a non-ergodic empirical model of the acceleration Fourier Amplitude Spectra (FAS), and then we adapt our tool in Spectral Amplitude (SA). Thanks to the large amount of high-quality seismic recordings (consisting of more than 400 earthquakes from magnitude 3.4 to 6.5, 460 stations, thus involving more than 30’000 waveforms in the time frame 2008-2018), we provide a statistical overview based on empirical evidence of seismological observations in the Central Italy area, which represents a unique natural laboratory for earthquakes occurring on normal faults. The non-ergodicity enables to remove all the other components of variability (i.e. the event-, site- and path-related) in the ground motion model (GMM) and hence allowing to better isolate the effects connected to source-directivity, that are not unaccounted in the epistemic variability of the ground motion. 

According to our criteria, about 36% of the analyzed events (162 out of 456) exhibits directivity. The distribution of the rupture directions is aligned, as expected, with the strikes of the major faults of the Central Apennines. We find that the directivity is a band-limited phenomenon, which spans from corner frequency (fc) up to approximately 5 times the event’s fc; in case of not very pronounced directivity, this band tends to be narrow, suggesting that the complex rupture processes at high-frequency are mainly stochastic. Moreover, we observe directivity not only during seismic sequences, but also in background seismicity. 

Preliminary results provide a useful hint regarding directivity’s parameterization as a frequency-dependent band-limited phenomenon, to be implemented in future ground motion modeling and scenario’s predictions. 
Potentiality of bedload measures using Acoustic Doppler Current  profiler technique
Authors: Gasparato Daniele , Herrera Gomez Lisdey Veronica , Ravazzani Giovanni , Mancini Marco
Published: March 2022

Bedload discharge measurement in riverine environment is crucial to monitor and understand the morphological evolution of the riverbed and its interaction with existing and new infrastructures.  Despite their relevance, bed load solid transport measures are most of time not available due to the difficulties in their acquisition.

The paper investigates the potentiality of Acoustic Doppler Current Profiler (ADCP ) technique, well established for measuring discharge and flow velocity in a river,  for the measure of bedload discharge in a more manageable way than the traditional ones.

A specific field campaign was organized at Boretto (Italy) cross section on the Po river where the riverbed sediment consists of uniform sand with a mean diameter of 0.4 mm. ADCP measures of bedload discharges were done at the same time as the ones acquired by traditional Helley Smith sampler.

The ADCP data are used in two different ways to obtain the value of the bedload solid discharge. The first approach computes the bedload discharge using the literature formulas where the shear velocities are computed by the logarithmic fit of the velocity profile given by the ADCP. The second approach uses the instrument Bottom Tracking function to obtain a measure of the sediment velocity on the river bed. The sediment velocity computed with this latter method is then used to calculate the bedload discharge with a kinematic model, whose parameters of active layer thickness and concentration are estimated using the Van Rijn model.

The comparison of traditional measures with the one based on the ADCP show comparable values of bed load discharges of the same order of magnitude.
Applicability of Smart-SED, a new sediment erosion and transport model, to Alpine scenarios 
Authors: Corti Monica , Gatti Federico , Abbate Andrea , Papini Monica , Longoni Laura
Published: March 2022

In recent times, the study of effective methods to deal with hydrological hazard in urban areas became more urgent in relation to the climate changes in act.

The development of tools able to predict the effects of extreme rainfall events is of great importance particularly for cities located at the downstream of mountain catchments, where exposure to floods and to the hazard related to sediment transport is relevant. Soil erosion and transport models are helpful instruments for the identification of hazardous areas and for risk management.

In this work, results gained applying an efficient simulation tool, developed by Politecnico di Milano research group and named Smart-SED, to different real case studies are presented.

The advantages of this new model over other tools already available in literature are the few input parameters required, the automatic identification of the drainage zones, the adaptive time step implied for the computations and the capability of dealing with multi-event simulations.

The proposed model was calibrated on a catchment locatedin the Southern Alps, in Northern Italy, and successfully validated, considering rainfall events of 2020 together with sediment and water discharge data collected in control points on the field. The calibrated model was then applied to another catchment in the proximity to evaluate flood risk in case of extreme rainfall events, such as catastrophic storms recently occurred in Northern Italy and climate change scenarios.
Atmospheric internal variability shapes the Arctic change and its feedback on local and remote circulation
Authors: Siew Peter Yu Feng , Li Camille , Ting Mingfang , Sobolowski Stefan , Wu Yutian , Chen Xiaodan
Published: March 2022

Arctic sea ice loss in recent decades has been proposed to influence atmospheric circulation at lower latitudes, producing feedbacks that amplify ice loss via thermodynamic and mechanical forcing. One proposed teleconnection pathway arises from autumn Barents-Kara sea ice reduction and leads to a negative North Atlantic Oscillation (NAO) in winter. The existence of such a pathway could improve predictions of  European weather on subseasonal to seasonal timescales. While autumn sea ice and the winter NAO are significantly correlated in satellite-era observations, this correlation appears to be absent in  coupled climate models, calling into question the underlying mechanism. By subsampling long simulations to create satellite-length records, we find a small number of samples across a range of CMIP5 and CMIP6 models that reproduce the observed correlation. In these samples, we observe similar circulation signals (e.g., weakening of the stratospheric polar vortex) as in the observations, but there is no evidence for a driving role from sea ice changes via turbulent heat fluxes. Rather than sea ice, blocking of the atmospheric circulation by the Ural mountains appears to be the key precursor to the winter NAO signal. Overall, our findings reconcile differences between observations and models in representing this Arctic-midlatitude teleconnection, and highlight the important role of atmospheric internal variability in Arctic change. 
A fast-slow model for glacial cycles since the Mid-Pleistocene Transition
Authors: Ajagun-Brauns Jade , Ditlevsen Peter
Published: March 2022

A new simple approach inspired by MacAyeal (1979) to explain the time-asymmetric ‘saw-toothed’ shape and 100,000-year quasi-period of glacial-interglacial cycles since the Middle Pleistocene Transition, is presented. Using a simple model with fast-slow dynamics, the global ice volume is taken to be a function of two independently varying parameters, the solar insolation and ‘alpha’, a secondary control parameter, the study of which is the focus this research. The steady state of the model is a partially folded surface in three-dimensional space where insolation, ‘alpha’, and global ice volume are orthogonal axes. The pleated surface allows for the gradual increase and sudden decrease in ice volume that is observed in the paleoclimate record. To derive a time series of global ice volume, the Euler integration method is used, producing a time series which replicates the ‘saw-toothed’ pattern of glacial cycles in the late Pleistocene. The second control parameter, ‘alpha’, is proposed to be related to internal dynamics of the climate system, such as ice sheet dynamics.

 

Reference

D. R.  MacAyeal, ‘A Catastrophe Model of the Paleoclimate Record’ , Journal of Glaciology , Volume 24 , Issue 90 , 1979 , pp. 245 – 257.
Sensitivity analysis of water balance components with the Noah-MP and WRF-Hydro models
Authors: Sofokleous Ioannis , Bruggeman Adriana , Eliades Marinos , Camera Corrado
Published: March 2022

The accurate simulation and partitioning of the water balance components is important for the simulation of hydrological processes and the interaction between the land and the atmosphere. The objective of this study is to identify the model parameters and parameterization options that impact the most the water balance components modelled with the Noah-MP land surface model coupled to the WRF-Hydro hydrological model. The water balance components are runoff and total evapotranspiration (ET), comprised of evaporation, transpiration and interception. Three types of different parameterization options and 12 model parameters were tested and the sensitivity of the model output was investigated for two consecutive hydrological years and for 31 watersheds in the Troodos mountains of Cyprus, in the Eastern Mediterranean. A baseline configuration, based on initial estimates of model parameters from previous literature and suggested default values, of the Noah-MP and WRF-Hydro model system was found to systematically overestimate the total streamflow of the 31 watersheds, with the median runoff coefficient equal to 0.4 compared to the observed value of 0.2. Consistent with the streamflow overestimation, the ratio of total ET to total precipitation was underestimated, with a value of 0.5 compared to the value of 0.8 from local observations. The sensitivity analysis revealed that specific parameters can substantially modify the amount of simulated streamflow and ET. The bedrock drainage parameter, hydraulic conductivity and soil porosity can each reduce or increase streamflow and ET up to 20% on average. Among the vegetation parameters and model parameterization options, the change of the dynamic vegetation option, the use of the Jarvis-based stomatal conductance model, instead of the Ball-Berry model, and the simulation of nocturnal transpiration can each increase ET by about 20%, and thus reduce the overestimation of total streamflow. The findings of this sensitivity analysis can be used to configure the Noah-MP and WRF-Hydro models in order to improve the simulation of the water balance of the studied area and other areas with similar hydroclimatic characteristics.
Transport Barriers and the Retention of Calanus finmarchicus on the Lofoten Shelf in Early Spring 
Authors: Dong Huizi , Zhou Meng , Hu Ziyuan , Zhang Zhaoru , Zhong Yisen , Basedow Sünnje , Smith Walker
Published: March 2022

Large aggregations of the copepod Calanus finmarchicus occur each spring in the shelf-slope-oceanic regions off the Lofoten-Vesterålen Islands where productive fisheries have traditionally supported local and global economies. The retention and off-shelf transport of C. finmarchicus populations were studied by analyzing ocean color remote sensing and satellite altimetry data between 2010 and 2019 and employing a Lagrangian Coherent Structures (LCS) model. Results revealed the existence of a transport barrier reoccurring at the shelf break that retains C. finmarchicus on the shelf for 30-70 days in the spring when C. finmarchicus were seasonally ascending to the surface layer. The analysis of baroclinic and barotropic energy conversions indicated that the topographically steered Norwegian Atlantic Current (NwAC) is the primary mechanism in the formation of the transport barrier, which restricts exchanges of C. finmarchicus populations between shelf and oceanic waters. In the mid- or late April, an increase in baroclinicity leads to an increase in mesoscale eddies generated on the shelf break near Lofoten-Vesterålen Islands, breaking down transport barriers and causing off-shelf transport of C. finmarchicus. The transport barrier predictably reoccurs in early spring which supports the entrapment of C. finmarchicus in the shelf region.
Late Cretaceous true polar oscillation artifact: further evidence for Earth’s long-term rotational stability
Authors: Cottrell Rory , Tarduno John , Bono Richard
Published: March 2022

Determining Earth’s stability with respect to the spin axis sets boundary conditions for understanding the planet’s deep mantle and interpreting records of past climate. Analyses of global paleomagnetic data sets have suggested very limited polar wander since the Mid-Cretaceous (Cottrell and Tarduno, 2000; Tarduno and Smirnov, 2001). However, this conclusion has been challenged by calls for a Late Cretaceous true polar oscillation whereby the entire solid Earth rotated by 12 degrees, and then rotated back, 86 to 78 million years ago (Mitchell et al., 2021). This posit is based on paleomagnetic data from a dense sampling (approximately 1000 limestone samples) and automated magnetic measurements yielding data from magnetic polarity chrons 34 to 32n in the Italian Apennines. Herein, we analyze these data and find that the oscillation signal across magnetic chrons polarity 33r to 33n exceeds the maximum speed constrained by mantle viscosity (2.4 degrees/myr; Tsai and Stevenson, 2007) and is thus physically implausible. When considered in the light of prior paleomagnetic and rock magnetic studies on these rocks, the data point to an unrecognized overprint magnetization carried by authigenic hematite. This overprint has a differential angular effect on the normal and reversed polarity primary remanences, creating biased magnetic directions and attendant false polar wander. This artifact serves as a cautionary tale with respect to paleomagnetic analyses, but also further highlights the remarkable stability of Earth relative to the axis since at least the mid-Cretaceous which sets the planet apart from smaller planetary bodies which may have experienced polar wander. Principal differences are that external forces since the lunar forming impact are too small to drive such motion, and Earth’s mantle viscosity structure which dampens any potential motion driven by changes in its mass heterogeneities.
Evaluations of Numerical Flux Schemes of a Coronal MHD Model
Authors: Zhang Fan , Perri Barbara , Brchnelova Michaela , Baratashvili Tinatin , Kuźma Błażej , Leitner Peter , Lani Andrea , Poedts Stefaan
Published: March 2022

Space weather forecasting requires precise estimation of the arrival time of eruptive events, which typically propagate through and interact with the solar atmosphere and solar wind. Therefore, the arrival time estimation depends on the accuracy of modelling the solar atmosphere and the complex interactions. For instance, the EUHFORIA 2.0 project expects an accurate and efficient coronal model that covers the region from the surface of the Sun up to 0.1AU, serving as the inner boundary condition for the heliospheric model.

Based on the open-source code COOLFluiD, we have developed a fully implicit MHD coronal model. The model has been validated by data-driven coronal simulations, and the fully implicit temporal solution significantly accelerates the numerical simulations. More physical mechanisms, e.g., the heating term(s), and numerical techniques, e.g., high-order schemes, are being developed to improve this model further. In this work, we specifically focus on the numerical flux schemes (Lax-Friedrichs, HLL, etc.) of the finite-volume MHD solver used by the coronal model, and evaluate their performance and impact on the coronal simulations. Both the internal structures and the quantities at the outer boundary are quantitatively compared.

This research has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 870405 (EUHFORIA 2.0).

 
Combining variational mode decomposition and recurrent neural network to predict rainfall time series and evaluating prediction performance by universal multifractals 
Authors: Zhou Hai , Schertzer Daniel , Tchiguirinskaia Ioulia
Published: March 2022

Rainfall time series prediction is crucial for geoscientific system monitoring, but it is challenging and complex due to the extreme variability of rainfall. In order to improve prediction accuracy, a hybrid deep learning model (VMD-RNN) was proposed. In this study, variational mode decomposition (VMD) is first applied to decompose the original rainfall time series into several sub-sequences according to the frequency domain. Following that, different recurrent neural network (RNN) models are utilized to predict individual sub-sequences and the final prediction is reconstructed by summing the prediction results of sub-sequences. These RNN models are long short-term memory (LSTM), gated recurrent unit (GRU), bidirectional LSTM (BiLSTM) and bidirectional GRU (BiGRU), which are optimal for sequence prediction. The root mean square error (RMSE) of the predicted performance is then used to select the ideal RNN model for each sub-sequences. In addition to RMSE, the framework of universal multifractal (UM) is also introduced to evaluate prediction performances, which enables to characterize the extreme variability of predicted rainfall time series. The study employed two rainfall datasets from 2001 to 2020 in Paris, with daily and hourly resolutions. The results show that, when compared to directly predicting the original time series, the proposed hybrid VMD-RNN model improves prediction of high or extreme values for the daily dataset, but does not significantly enhance the prediction of zero or low values. Additionally, the VMD-RNN model also outperforms existing deep learning models without decomposition on the hourly dataset when evaluated with the help of RMSE, while universal multifractal analyses point out limitations. 
Extreme wind projections over Europe from the Euro-CORDEX regional climate models
Authors: Sobolowski Stefan , Outten Stephen
Published: March 2022

Extreme weather events represent one of the most visible and immediate hazards to society. Many of these types
of phenomena are projected to increase in intensity, duration or frequency as the climate warms. Of these extreme winds are
among the most damaging historically over Europe yet assessments of their future changes remain fraught with uncertainty.
This uncertainty arises due to both the rare nature of extreme wind events and the fact that most model are unable to faithfully
represent them. Here we take advantage of a 15 member ensemble of high resolution Euro-CORDEX simulations (∼12km)
and investigate projected changes in extreme winds using a peaks-over-threshold approach. Additionally we show that - de-
spite lingering model deficiencies and inadequate observational coverage - there is clear added value of the higher resolution
simulations over coarser resolution counterparts. Further, the spatial heterogeneity and highly localized nature is well captured.
Effects such as orographic interactions, drag due to urban areas, and even individual storm tracks over the oceans are clearly
visible. As such future changes also exhibit strong spatial heterogeneity. These results emphasise the need for careful case-by-
case treatment of extreme wind analysis, especially when done in a climate adaptation or decision making context. However,
for more general assessments the picture is more clear with increases in the return period (i.e. more frequent) extreme episodes
projected for Northern, Central and Southern Europe throughout the 21st century. While models continue to improve in their
representation of extreme winds, improved observational coverage is desperately needed to obtain more robust assessments of
extreme winds over Europe and elsewhere.
Seismotectonic evidence for present-day transtensional reactivation of the slowly deforming Bodensee-Hegau Graben in the northern foreland of the Central Alps
Authors: Diehl Tobias , Madritsch Herfried , Schnellmann Michael , Spillmann Thomas , Brockmann Elmar , Wiemer Stefan
Published: March 2022

This study presents a seismotectonic analysis of the Miocene-aged Bodensee-Hegau Graben, a major tectonic element in the northern foreland of the European Central Alps. The graben is characterized by comparatively low strain rates and low to moderate seismicity. Our study builds on the seismological analysis of earthquakes recorded by a recently densified seismometer network. The derived high-precision absolute and relative hypocenter relocations allow to identify seismogenic structures in the pre-Mesozoic basement, which we relate to bounding faults on either side of the NW-SE striking graben. A cluster of seismicity on the SW side of the graben is associated with the previously mapped Neuhausen Fault. In contrast, the seismogenic, SW-dipping bounding faults on the opposite side of the graben, between the extinct Hegau volcanic field and the Bodanrück peninsula of Lake Constance, cannot be associated with any known fault. A set of 51 focal mechanisms allows for a high-resolution analysis of kinematics and stress regime of the graben. Our results show that the bounding faults of the graben are optimally oriented to be reactivated in transtensional mode in the present-day stress field. Slip rates across the Neuhausen and Randen faults estimated from geodetic data are likely <0.1 mm/yr. In comparison with historic seismicity over the past 600 years and geomorphic field observations, these rates appear overestimated. Nevertheless, historic seismicity over the past 600 years suggests that fault dimensions and slip rates are certainly sufficient to generate MW 5.0 earthquakes within this slowly deforming transtensive fault zone in the foreland of the Alpine collision zone.
Flood analysis using satellite imagery and machine learning within Google Earth Engine: A catchment-based study in Northern Iran
Authors: Rashidpour Mostafa , Motagh Mahdi , Solaimani Karim , Hadian Amri Mohammadali , Roessner Sigrid , Shahedi Kaka
Published: March 2022

Knowledge about the location and extent of flooded areas in large catchments with different rainfall- runoff response in each sub-catchment is of key importance for planning flood management strategies. Haraz catchment with an area of more than 4000 square kilometers is located in the north of Iran and is frequently affected by floods. The lack of reliable spatiotemporal information on flood occurrence has been the main limiting factor for assessment of flood hazard and risk in this catchment.

The current availability of satellite remote sensing sensors with high spatial and temporal resolution is highly valuable for detailed analysis of individual flood occurrence across various scales. In this study, we develop a machine learning approach using data from various remote sensing sensors including Landsat, Planet and Sentinel-2 to detect flood events in different tributary areas within the Haraz catchment which have occurred between 2015 and 2021. The random forest algorithm implemented in Google Earth Engine was used for image classification before and after flood events. The areas of each landcover type inundated by flood waters were calculated for the single flood events and the binary flood masks were overlaid on the study area. The results have revealed that seven flood events could be detected, whereas the two events in April 2015 and April 2019 had led to the largest areas of inundation because of the nature of these floods as riverine flood. Moreover, we have found that two parts of the river network – one in middle part of Norroud subcatchment adjacent to Baladeh City and another one in the area of the catchment outlet - have the largest potential for flood risk because of the frequency of inundation and the high vulnerability of built-up areas that occupy the floodplain. Thus, the findings of this study form the basis for a better understanding of the characteristics for recent flood hazard and risk in Haraz catchment.
Modified soil hydro-thermodynamics cause large spread in projections of Arctic and subarctic climate
Authors: Steinert Norman Julius , González-Rouco Jésus Fidel , de Vrese Philipp , García-Bustamante Elena , Hagemann Stefan , Jungclaus Johann , Lorenz Stephan , Brovkin Victor , Melo-Aguilar Camilo Andres , García-Pereira Félix , Navarro Jorge
Published: March 2022

The representation of the terrestrial thermal and hydrological states in current-generation climate models is crucial to have a realistic simulation of the subsurface physical processes and land-atmosphere coupling. This is particularly important for high-latitude permafrost regions since these areas are prone to the release of substantial amounts of carbon from degrading permafrost under climate-change conditions. Many current-generation climate models still have deficiencies in the representation of terrestrial structure and physical mechanisms, such as too shallow land depth or insufficient hydro-thermodynamic coupling. We therefore introduce a deeper bottom boundary into the JSBACH land surface model. The associated changes in the simulated terrestrial thermal state influence the near-surface hydroclimate when sufficient coupling between the thermodynamic and hydrological regimes is present. Hence, we also assess the influence of introducing various physical modifications for the representation of soil hydro-thermodynamic processes in climate projections of the 21st century. The results show significant impacts on terrestrial energy uptake, as well as changes in global near-surface ground temperatures when introducing the physical modifications. The resulting simulation of high-latitude permafrost extent is subject to large variations depending on the model configuration, reflecting the uncertainty of carbon release from permafrost degradation. We further use the modified model to assess the sensitivity of simulated high-latitude climate dynamics to different hydrological configurations in the coupled MPI-ESM. The differences in soil hydrological representation in permafrost regions could explain a large part of CMIP6 inter-model spread in simulated Arctic climate, with remote effects on subarctic dynamical systems.
Unraveling archaeological settlement, landscape, and resource use patterns with machine learning in Kurdistan (Iraq)
Authors: Bellat Mathias , Glissmann Benjamin , Rentschler Tobias , Schmidt Karsten , Sconzo Paola , Pfälzner Peter , Scholten Thomas
Published: March 2022

       The traditional view on Mesopotamian resources strategies is understood as “resource hunting” in which Mesopotamian empires would have spread to neighbouring regions (Zagros, Taurus, Levant…) to monopolize their resources. Indeed, Mesopotamia lacks some resources/raw materials such as copper, iron, wood, obsidian, and others. Our RessourceCultures approach, developed in SFB 1070, aims to define resources in a wider spectrum, to propose new interpretations on cultures development in this region. By investigating new patterns rules of resources appropriation and uses in peripheral areas, we hope to bring interesting new results. Our survey covered an area of 4.400 km2 from the western foothills of the Zagros mountains to the eastern riverbank of the Tigris. 

 

      To unravel the patterns that define a ResourceCulture we combine both archaeological and geoarchaeological data into a machine learning approach. Many features (topography, water, soil type, resources availability, climate…) influence the founding and location of settlements in different ways and degrees of importance. The trend of these influences can be analyzed through machine learning models in predictive archaeology. Letting the machine run predictive models and underline the relationship between each feature and settlement dynamic will potentially help us to better understand how resources were used in a cultural and economic context through time and space.     

 

           Our poster will present the first ideas derived from the machine learning approach: Is there any trends appearing and what can we say from them? Can we redefine the ResourceCulture in Northern Mesopotamia through these new interpretations? 
An international perspective on comprehensive climate risk management: experiences from Peru, India and Austria
Authors: Hagen Isabel , Allen Simon , Bahinipati Chandra S. , Frey Holger , Huggel Christian , Karabaczek Veronica , Kienberger Stefan , Mechler Reinhard , Menk Linda , Schinko Thomas
Published: March 2022

Climate-related sudden-onset events (e.g., floods, cyclones) and slow-onset processes (e.g., sea level rise and heat waves) pose a major risk to communities all over the world. With intensifying climate change in combination with unequal socioeconomic development, climate-related risks are expected to escalate in the future, potentially leading to critical losses and damages. This calls for efficient and achievable risk management strategies. Climate Risk Management (CRM) is a leading approach to identify, assess and reduce risks, through an integration of Disaster Risk Reduction, Climate Change Adaptation, and sustainable development. CRM aims at comprehensively managing risks and increasing resilience and adaptive capacity. To date, several conceptual CRM frameworks have been developed, which have, however, rarely been applied to real-world cases.

Based on this conceptual literature, we further develop a comprehensive CRM framework, comprising both the risk assessment as well as the implementation and monitoring domains of CRM, and test it on three real-world risk cases in Peru, India and Austria. The cases have distinct spatial scales, from local level in Peru, to district level in India, to nationwide in Austria. The risks covered in these cases are linked to different hazards, ranging from glacier lake outburst floods (Peru), sea level rise, salinization and cyclones (India), to riverine flooding and agricultural droughts (Austria).

The aim of this complementary case study approach is to validate the overall structure and individual steps of the CRM framework against actual risk management practices in the three case studies. Based on the specific results and common insights from the three cases, we are able to (1) evaluate the applicability of the proposed conceptual CRM framework in real world circumstances, (2) present evidence on the extent to which comprehensive management of climate-related risks has been achieved in the three cases, and (3) synthesize policy recommendations towards an achievable comprehensive CRM in practice, acknowledging specific local contexts and characteristics.