bluuebunny/crossref_metadata_2025 huggingface dataset:
Definition of a new multi-level early warning procedure for landslide risk management
Authors: Valletta Alessandro , Carri Andrea , Savi Roberto , Cavalca Edoardo , Segalini Andrea
Published: March 2020

The identification of potentially critical events involving unstable slopes is a major aspect in the field of natural hazards risk mitigation and management. In this framework, Early Warning Systems (EWS) exploiting advanced technologies represent an efficient approach to decrease the risk generated by landslide phenomena, allowing to reduce the possibility of damages and losses of human lives. EWS effectiveness has increased significantly in recent years, thanks to relevant advances in sensing technologies and data processing. In particular, the introduction of innovative monitoring instrumentation featuring automatic procedures and increased performances in terms of sampling rate and accuracy has permitted to develop EWS characterised by a near-real time approach. Among the several aspects involved in the development of a reliable Early Warning System, one of the most important is the ability to minimize the dissemination of false alarms, which should be avoided or identified in advance. The approach proposed in this study represents a new procedure aimed to assess the hazard level posed by a potentially critical event, previously identified by analysing displacement monitoring data. The process is implemented in a near-real time EWS and defines a total of five different hazard levels, on the basis of the results provided by two different models, namely an accelerating trend identification criterion and a failure forecasting model based on the Inverse Velocity Method (IVM). In particular, the forecasting analysis is performed only if the dataset elaborated by the onset-of-acceleration model highlights a potentially critical behaviour, which represents a first alert level. Following levels are determined by different conditions imposed on three parameters featured by the failure forecasting model, i.e. dataset dimension, coefficient of determination R-squared, and number of sensors displaying an accelerating trend. As these criteria get fulfilled, it is assumed that the monitored phenomenon is gradually evolving towards a more critical condition, thus reaching an increasing alert level depending on the analysis results. According to this classification, it is possible to set up for each single threshold a dedicated warning message, which could be automatically issued to authorities responsible of monitoring activities, in order to provide an adequate dissemination of information concerning the ongoing event. Moreover, the proposed procedure allows to customize the alert approach, giving the possibility to issue warning messages only if a certain Level is reached during the analysis.
A Study of Debris Flow Behaviors According to Rheometer Properties: Focused on the Hwangnyeong Mt. and Umyeon Mt.
Authors: Kim Hyeong-Jin , Yun Dae-Ho , Kim Yun-Tae
Published: March 2020

A debris flow, a mass movement of soil and water mixture, is generally occurred by heavy rainfall during the rainy season in Korea. Because of climate change, the amount and frequency of rainfall has continually increased these days. Populated areas located in debris flow-prone mountainous areas are commonly subject to debris flow hazards. For this reason, it is necessary to analyze the characteristics of the debris flow behavior for the hazard mitigation. In this study, for two samples from Hwangnyeong Mt. and Umyeon Mt. in Korea, the vane-type rheometer test were performed to estimate the rheological property such as viscosity and yield stress and small-scale flume experiment was carried out to evaluate the characteristics of debris flow behaviors such as front velocity, runout distance and deposition volume. From the experimental results, rheological properties decrease with decreasing volumetric sediment concentration, and debris flow behavior gradually increased with decreasing rheological properties in the experiment. Additionally, in case of Hwangnyeong Mt. which has a high silt and clay fraction, the experimental results show that the amount of the front velocity, runout distance and deposition volume tend to increase higher than Umyeon Mt. as viscosity and yield stress decreased.
Impact of rainforest transformation into oil-palm plantations on Si pools in soils
Authors: Greenshields Britta , von der Lühe Barbara , Hughes Harold J. , Tjoa Aiyen B. , Sauer Daniela
Published: March 2020

As oil-palm plantations are expanding rapidly in SE Asia, it is essential to ensure that soil functions are sustained after land-use transformation. This includes the maintenance of well-balanced soil nutrient levels to prevent soil degradation as well as understanding soil silicon (Si) dynamics to optimize oil-palm management. However, studies on the influence of oil-palm cultivation on soil Si pools have not yet been undertaken, although it is known that oil palms accumulate Si in their biomass and should thus affect Si pools and cycling. We hypothesized that under oil-palm monocultures, Si losses may exceed Si input into soils, due to (1) erosion of phytolith-enriched topsoils, (2) increased Si uptake by oil palms, (3) harvest and palm-frond management. The aim of this study is to compare Si pools in Acrisols of Sumatra (Indonesia) under rainforest and oil-palm plantations to assess whether these soil Si pools are significantly depleted under oil-palm plantations. We included both well-drained and riparian sites, hypothesizing that riparian sites are less prone to net Si depletion, as they receive additional Si through regular flooding and slope water from higher areas. Soil samples (1 g) from soil profiles (≤ 1 m, n = 4 for each land-use type and topographic position) were subjected to sequential Si extraction to determine mobile Si, adsorbed Si, Si in soil organic matter, Si occluded in pedogenic oxides and hydroxides, and biogenic Si.

Si in soil organic matter (SOM) and biogenic Si represent the largest Si pools in the Acrisols. Our preliminary results suggest that these pools are controlled by land use rather than by topographic position (riparian versus well-drained). Ah horizons under oil-palm plantations have lower contents of Si in SOM (0.052-1.04 mg g-1) than those under rainforest (0.59-1.5 mg g-1). There is no significant difference between well-drained and riparian sites, as Si input by slope water and flooding does not affect Si in SOM. Besides, the concentrations of biogenic Si are lower in soils under oil-palm plantations than under rainforest. The contents of both mobile and adsorbed Si in soils are similar to marginally higher in riparian soils (5-30 µg g-1), compared to well-drained soils (5-20 µg g-1), with no clear difference between land-use types. These Si fractions unlike Si in SOM are most directly influenced by Si input through slope water and flooding.
Impact of deep-sea polymetallic nodule mining on benthic microbial community and mediated biogeochemical functions
Authors: Molari Massimiliano , Vonnahme Tobias R. , Janssen Felix , Wenzhöfer Frank , Haeckel Matthias , Tischack Jürgen , Boetius Antje
Published: March 2020

Industrial-scale mining of deep-sea polymetallic nodules will remove nodules in large areas and impact the physical integrity of the seafloor. However, environmental standards for seafloor integrity and studies of recovery from environmental impacts are still largely missing. Further we have only a poor understanding of the role of nodules in shaping benthic microbial diversity and element cycles. We revisited the deep-sea disturbance and recolonization experiment carried out with a towed plough harrow in 1989 in the Peru Basin nodule field within a circular area of approx. 3.5 km diameter (>4100 m water depth). In the experimental area, the 26 years old plough tracks were still visible and showed different types and levels of disturbance such as removal and compaction of surface sediments. Microbial communities and their diversity were studied in disturbance tracks and undisturbed sites and related to habitat integrity, remineralization rates, and carbon flow. Locally, microbial activity was reduced up to 4 times in the impacted areas. Microbial cell numbers were reduced by ~50% in fresh, and by <30% in the old tracks. Our data suggest that microbially-mediated biogeochemical functions need more than 50 years to return to undisturbed levels in the sediments. In areas with nodules (i.e., outside the disturbance tracks) microbial communities in the nodules themselves were studied. Nodule communities were distinct from sediments and showed a lower diversity and a higher proportion of sequences related to potential metal-cycling bacteria (i.e. Magnetospiraceae, Hyphomicrobiaceae), bacterial and archaeal nitrifiers (i.e. AqS1, unclassified Nitrosomonadaceae, Nitrosopumilus, Nitrospina, Nitrospira), as well as bacterial sequences typically found in ocean crust, hydrothermal deposits and sessile fauna. Our results confirm that nodules host specific microbial communities with potentially significant contributions to organic carbon remineralization and metal cycling. This study contributes to developing environmental standards for deep-sea mining and highlights the limits for maintaining and recovering ecological integrity and functions during large-scale nodule mining.
Data-driven parametrizations in numerical models using data assimilation and machine learning.
Authors: Brajard Julien , Carrassi Alberto , Bocquet Marc , Bertino Laurent
Published: March 2020

Can we build a machine learning parametrization in a numerical model using sparse and noisy observations?

In recent years, machine learning (ML) has been proposed to devise data-driven parametrizations of unresolved processes in dynamical numerical models. In most of the cases, ML is trained by coarse-graining high-resolution simulations to provide a dense, unnoisy target state (or even the tendency of the model).

Our goal is to go beyond the use of high-resolution simulations and train ML-based parametrization using direct data. Furthermore, we intentionally place ourselves in the realistic scenario of noisy and sparse observations.

The algorithm proposed in this work derives from the algorithm presented by the same authors in https://arxiv.org/abs/2001.01520.The principle is to first apply data assimilation (DA) techniques to estimate the full state of the system from a non-parametrized model, referred hereafter as the physical model. The parametrization term to be estimated is viewed as a model error in the DA system. In a second step, ML is used to define the parametrization, e.g., a predictor of the model error given the state of the system. Finally, the ML system is incorporated within the physical model to produce a hybrid model, combining a physical core with a ML-based parametrization.

The approach is applied to dynamical systems from low to intermediate complexity. The DA component of the proposed approach relies on an ensemble Kalman filter/smoother while the parametrization is represented by a convolutional neural network.  

We show that the hybrid model yields better performance than the physical model in terms of both short-term (forecast skill) and long-term (power spectrum, Lyapunov exponents) properties. Sensitivity to the noise and density of observation is also assessed.
Coupled chemical osmosis and rock deformation processes in semipermeable mudstone- theoretical and experimental approaches-
Authors: Hirota Shogo , Tokunaga Tomochika , Aichi Masaatsu , Xue Ziqiu , Park Hyuck
Published: March 2020

Slow groundwater flow and mass transport processes in mudstone sometimes exhibit non-Darcian flow. For example, it is known that some mudstone shows semipermeable properties because of its negative charge of clay minerals and narrow pore throats (Marine and Fritz, 1981). In such formations, osmotic flow, water flow driven by osmotic pressure, occurs and it induces pore pressure change in low-permeability or hydraulically isolated area (Marine and Fritz, 1981). If large pore-water concentration difference exists in tight and clay-rich formation, osmosis-induced pore pressure can reach to about 20MPa(Neuzil, 2000). Change of pore pressure causes deformation of porous medium.  Osmosis-induced pore pressure change can cause deformation of porous medium (Greenberg et al., 1973: Noy et al., 2004) and it is possible that large concentration difference causes rock deformation or destruction in semipermeable formations.

The purpose of this study is to establish a model which describes pressure behavior, solute transport, and deformation of semipermeable mudstone and to discuss the validity of the model through comparing the model result and the results obtained from laboratory experiments. The numerical model is established by coupling the equations of solute transport and pressure behavior in semipermeable mudstone(for example Malusis et al., 2012), and that of poroelasticity (for example Wang, 2000). For laboratory experiments, core samples with 50mm in diameter and 30mm in height were prepared from mudstone samples collected from Neogene formation in Japan. NaCl solution with 10 g/L higher than that of pore water was contacted to one of the surfaces of the sample, and all the other surfaces were sealed with silicone rubber. Longitudinal deformation of the sample surface was measured. Here, optical fiber sensing technique was used to measure strain behavior, and hence, it was possible to measure strains at multi point of the sample. The measurement was continued more than 240hr.

In the presentation, the comparison of results obtained from experiments and calculations will be shown and the significance will be discussed.
Detailed statistical analysis of the Gole Larghe Fault Zone fracture network (Italian Southern Alps) improves estimates of the energy budget for intraplate earthquakes in basement rocks
Authors: Bistacchi Andrea , Mittempergher Silvia , Smith Steve A.F. , Di Toro Giulio , Nielsen Stefan
Published: March 2020

We present a study on the paleoseismic Gole Larghe Fault Zone (GLFZ), composed of hundreds of sub-parallel faults hosted in tonalites of the Adamello Massif (Italian Southern Alps), where we collected a complete transect across the fault zone, including the background host rocks, over a thickness of >1km.

Along this transect, we studied the correlation between fracture spacing (for “fracture” here we mean joints, veins, faults, shear fractures, and all other brittle structures) and position with a robust non-parametric approach. This analysis, new for fracture distribution studies, allows detecting volumes of the fault zone with clustering or a trend in spacing, versus volumes where the spatial distribution is stationary. The analysis reveals that the GLFZ can be subdivided in “stationary volumes” where fractures shows stationary statistical properties. Each one of these volumes can be completely characterized with scanline and/or scanarea surveys to obtain a complete and statistically sound estimate of all fracture parameters (spacing, intensity, density, length, height, orientation, topology, etc.).

Within the GLFZ we have two main classes of structures: (i) “master” faults that are sub-parallel to the fault zone and are always characterized by pseudotachylytes and/or cataclasites, and (ii) minor “fractures” (e.g. Riedel fractures, joints, veins, etc.) that are oblique to the fault zone and interconnect the former. Out of the GLFZ we observe a background fracturing that is associated to the cooling of the Adamello tonalites under deviatoric tectonic stress (“cooling joints”).

By comparing fracture statistics within and outside the fault zone, we demonstrated that master faults within the GLFZ were almost completely inherited from the “cooling joints” of the host rocks. The cooling joints just grew in length and became completely interconnected at the scale of the seismic rupture. This means that, at least in the case of the GLFZ, the large faults and fractures along which seismic ruptures were running do not add significantly to the earthquake energy budget, because they were already present in the system before the onset of seismic activity. The only fractures to be considered in this budget are the minor interconnecting fractures (e.g. Riedel fractures, joints, veins, etc.) that are coated with pseudotachylytes.

These observations confirm once again the classical assumption that seismic ruptures propagate along pre-existing discontinuities and do not, in general, tend to fracture intact rocks.
Further developments on estimating inertia-gravity-wave properties: Combining the Riesz transform with machine learning methods
Authors: AmirAmjadi Mozhgan , Mohebalhojeh Ali R. , Mirzaei Mohammad
Published: March 2020

One of the remaining issues in the parameterization of inertia-gravity waves is the estimation of wave characteristics such as wavenumber and intrinsic frequency. In this survey, we explore a new way to estimate the wave characteristics at the launch level. To this end, we retrieve the wavenumber using the Riesz Transform which is the generalized form of the Hilbert Transform applicable in the multi-dimensional analysis. For this purpose, the high-resolution horizontal divergence field has been employed since it filters the background flow and thus provides a reasonable representation of the inertia-gravity wave signal. This is followed by the application of machine learning to reconstruct the retrieved wavenumber using the coarse-grained resolvable variables including the horizontal wind speed, the large scale vertical velocity, the cross-stream ageostrophic wind speed, the frontogenesis function and the latent heat released during condensation as explanatory variables at the launch level.
We have employed the ERA5 dataset in this survey, having observed that the dataset can directly resolve the inertia-gravity waves at its full resolution. In order to avoid mountain waves and focus on non-orographic inertia-gravity waves, two areas far from the significant obstacles over the midlatitude of the Atlantic Ocean and Northern Pacific Ocean are considered from December 2018 to February 2019. The results show a reasonable correlation between the reconstructed wavenumber using low-resolution explanatory variables and the retrieved one using the Riesz Transform so that this method can be utilized to estimate the inertia-gravity wave number at the launch level.
The trade-off between vegetation restoration and soil & water conservation in Loess Plateau, China
Authors: Gao Haiqiang , Liu Shuguang
Published: March 2020

China has implemented an ambitious ecological project Grain for Green Project (GGP) on the Loess Plateau (LP) at the end of last century. The GGP was to increase vegetation coverage, reduce soil and water erosion and store Carbon by converting croplands on steep slopes barren hills and wasteland to forests. Assessing the ecological effects of GGP correctly could improve vegetation restoration activities worldwide. In this study, two major ecological indicators (vegetation restoration and soil & water conservation) were used to evaluate the ecological benefits of GGP from 1982 to 2017. Our results show that the vegetation growth for most pixels of LP region have significantly increased at 21 century, annual growth rates of fraction of absorbed photosynthetically active Radiation (FPAR) in spring, summer, autumn and active growing season are 1.39, 4.49, 2.14 and 1.47, respectively. For leaf area index (LAI), these growth rates are 6.01, 20.06, 8.11 and 6.90, respectively. And for normalized difference vegetation index (NDVI), growth rates are 6.30, 25.46, 7.99 and 20.43, respectively. While the soil and water condition has differently changed, annual growth rates of soil moisture (SM) are 4.46, 2.79 and 2.30 for summer, active growing season and whole year, respectively. The coordinated responses of vegetation and soil & water condition suggest that the interaction between organisms (vegetation, animal and human) and environment (soil, water and so on) in the process of vegetation restoration should be further recognized to evaluate the benefits of ecological engineering more comprehensively.
The change of MJO teleconnection under the global warming
Authors: Tseng Wan-Ling , Hsu Huang-Hsiung , Jiang Li-Chiang , Chang Chiung-Wen June , Tsuang Ben-Jei , Tu Chia-Ying
Published: March 2020

Global warming’s impact on the Madden-Julian Oscillation (MJO) is assessed using one of the few models capable in reproducing its key features. In a warmer climate predicted for the end of the century, it has been proved the MJO increases in amplitude and frequency, showing a more circumglobal propagation tendency. Here, we examine the MJO teleconnection and its extratropical response under the warmer climate by the time-slide experiments. The extratropics impact on different phase is shifted through the change of the mean atmospheric circulation. The strengthening of the midlatitude jet stream leads to the zonal extended wave propagation. It results the stronger variability of the atmospheric river to the America west coast. Moreover, the relationship with the NAO and PNA is weaker but the stronger fluctuation is shown in the polar area. This suggests the teleconnection of the North America weather by the tropical convection is going to change in the warming climate. It is essential to consider in the further projection and subseasonal to seasonal forecast.
Estimation of surface CO2 flux in East Asia and comparison with the national greenhouse gases emission inventory
Authors: Cho Minkwang , Kim Hyun Mee
Published: March 2020

 In this study, surface carbon dioxide (CO2) flux was estimated over East Asia using the inverse modeling approach. Two CO2 mole fraction datasets observed from South Korea (Anmyeon-do (AMY) and Gosan (GSN)), along with ObsPack observation data package, were additionally assimilated in the CarbonTracker system, and the characteristics of the estimated surface CO2 flux was analyzed over ten years. To see the impact of the inclusion of the two observation datasets in the Korean Peninsula, the other experiment which only assimilated the ObsPack data was conducted and used for comparison.

 The result showed that by including two more datasets in the data assimilation process, the surface CO2 flux absorption was slightly enhanced in summer and the surface CO2 flux emission was weakened in late autumn and spring. This characteristic was shown particularly in Eurasian boreal and Eurasian temperate regions. Validation was done using independent observations from surface and aircraft (Comprehensive Observation Network for Trace gases by Airliner; CONTRAIL), and it showed smaller root mean square error (RMSE) values and bigger uncertainty reduction effect with the experiment which additionally assimilated two Korean observation datasets.

 Meanwhile, the estimated biosphere CO2 flux from the CarbonTracker was compared with Land Use, Land Use Change and Forest (LULUCF) sector CO2 emission (or absorption) from the national greenhouse gases emission inventory (NIR). In case of South Korea, the observation density (number of observation sites or number of assimilated data on the area of the region) seemed to be related to some statistic parameters between inventory and CarbonTracker result. More results from model-inventory comparison using other data will be presented in the meeting.

 

Acknowledgements

 This study was supported by the Korea Meteorological Administration Research and Development Program under grant KMI2018-03712 and a National Research Foundation of Korea (NRF) grant funded by the South Korean government (Ministry of Science and ICT) (Grant 2017R1E1A1A03070968). The authors thank Andrew R. Jacobson for providing the CarbonTracker used for this study.
Spatiotemporal response of an Alpine braided river reach to snow melt and flood events
Authors: Bakker Maarten , Gimbert Florent , Misset Clément , Borgniet Laurent , Recking Alain
Published: March 2020

Alpine environments are responding to accelerated climate warming through the release and mobilization of large amounts of unconsolidated sediment. Sediment fluxes delivered to Alpine streams may be buffered, filtered and/or modulated as they pass through braided river reaches, which play a key role in the downstream transfer and dynamics of bed material. The functioning of these braided reaches is however still poorly understood, particularly during high magnitude events whose effects are very difficult to monitor but play an ever more prominent role in river system evolution.

In this study, we investigate the transfer of bedload material and river bed morphological change in a braided reach of the Séveraisse River (France), over the course of the melt season and two large flood events with an estimated return period of 5 and 50 years. To quantify braided reach dynamics, a multi-physical approach is employed that combines both temporally and spatially resolved techniques. We use bank-side geophones and locally derived parameters that describe seismic wave propagation in the subsurface to accurately quantify bedload transport and gain a unique insight in its temporal dynamics, particularly during the flood events. River bed elevation changes are determined from intermittent UAV-based LiDAR and photogrammetric acquisition. These are complemented with hourly (daytime) time-lapse images that register planform changes during the flood events.

Our results show strongly contrasting morphodynamic behavior with different flow conditions. During ‘normal’ bedload transport conditions driven by annual snow-melt, channel aggradation occurs leading to progressively lower bedload export from the reach for a given discharge. During the flood with a 5 year return period, which occurred at the end of the melt season, the braided riverbed morphology is rearranged and net sediment export took place. Most interestingly, in the autumn an extreme flood event led to the development of a single channel, meandering planform with significant outer bend erosion on alternating banks. Although this morphological change may be only temporary, i.e. a braided configuration may be expected to be gradually re-instated, it has important implications on the general functioning and morphological evolution of the reach and the downstream transfer of sediment.
The impact of thermohaline staircases: estimates from a global analysis of Argo floats
Authors: van der Boog Carine , Pietrzak Julie D , Dijkstra Henk A , Katsman Caroline A
Published: March 2020

Thermohaline staircases are stepped structures in the temperature and salinity stratification that result from double diffusive processes. In the open ocean, double diffusive processes enhance the downgradient diapycnal heat transfer compared to turbulent mixing. However, in combination with salinity effects, the resulting buoyancy flux within the thermohaline staircases is counter gradient. This vertical density transport strengthens the stratification and, consequently, affects the density of the water masses above and below the staircase layer. Although 44 percent of the world’s oceans is susceptible to double diffusion and thermohaline staircases are ubiquitous in these regions, the impact of double diffusion on diapycnal heat transfer and on water mass transformation has not been quantified yet. Here, we analyse a dataset of Argo float profiles to obtain a global overview of the occurrence of thermohaline staircases and to estimate their impact on diapycnal heat transfer and water mass transformation. Several regions with a high staircase occurrence are identified. Besides the well-known regions in the Caribbean Sea, the Mediterranean Sea and the subtropical Atlantic Ocean, our analysis reveals a new staircase region in the Indian Ocean. Using this global overview, we estimate, for the first time, the contribution of downgradient diapycnal heat transfer by the staircases. It appears that this contribution is very low compared to the dissipation required to maintain the observed temperature stratification. However, each staircase region can potentially impact the global circulation by affecting the density of the water masses above and below. In particular, the staircase region in the Indian Ocean overlies the waters of the Tasman Leakage. These waters flow westward from Australia towards the Agulhas region and affect the properties of waters entering the Atlantic Ocean. This implies that the vertical flux of salt into the Tasman Leakage waters induced by the presence of thermohaline staircases above can impact the salt transport into the Atlantic Ocean, which in turn is expected to impact the Atlantic Meridional Overturning Circulation. 
Glacio-metrological measurements of Patsio glacier, Himachal Pradesh (India), Western Himalaya
Authors: Angchuk Thupstan , Ramanathan Allagapan , Mandal Arindan , Soheb Mohd , Mishra Somdutta , Vatsal Sarvagya
Published: March 2020

We present the glacio-metrological measurements on the Patsio glacier, located in the Lahaul-Spiti region, Himachal Pradesh, western Himalaya. In-situ annual and seasonal mass balance measurements have been monitored since 2010 and 2012 respectively. Subsequently, an automatic weather station was installed in the summer of 2015. The baseline investigations show a large variability in meteorological conditions during different seasons. Summer was warm and calm, whereas winter is cold and windy with high precipitation, especially snow. Peak ablation months were July and August. Mean annual temperature over the study period was low (-6.3 °C). January recorded as the coldest month and July as hottest corresponding to a mean of -16.8 and 4.28 °C, respectively. Two contrasting wind flow over the Patsio glacier valley was prominent. The persistent katabatic flow was observed during the winter season and up-valley wind in summer. A classic Temperature Index Model was used to estimate the melt from the Patsio glacier, for the years 2016 and 2017. Degree-day factor (DDF) for various components (snow, ice, and debris covered ice) was estimated using field data. High DDFs for snow, ice, and debris-covered ice were observed compared to other studies. The simulated results (snow and ice) were in good agreement with observed data (R2 = 0.88 in 2016 and 0.93 in 2017). Temperature is the main governing factor in inducing the melt. This study gives insight the metrological conditions together with snow and ice melt of Patsio glacier situated in the high and dry region of the Himalaya.
Verification of post-processed seasonal predictions
Authors: Düsterhus André
Published: March 2020

Traditionally, verification of (ensemble) model predictions is done by comparing them to deterministic observations, e.g. with scores like the Continuous Ranked Probability Score (CRPS). While these approaches allow uncertain predictions basing on ensemble forecasts, it is open how to verify them against observations with non-parametric uncertainties.

This contribution focuses on statistically post-processed seasonal predictions of the Winter North Atlantic Oscillation (WNAO). The post-processing procedure creates in a first step for a dynamical ensemble prediction and for a statistical prediction basing on predictors two separate probability density functions (pdf). Afterwards these two distributions are combined to create a new statistical-dynamical prediction, which has been proven to be advantageous compared to the purely dynamical prediction. It will be demonstrated how this combination and with it the improvement of the prediction can be achieved before the focus will be set on the evaluation of those predictions at the hand of uncertain observations. Two new scores basing on the Earth Mover's Distance (EMD) and the Integrated Quadratic Distance (IQD) will be introduced and compared before it is shown how they can be used to effectively evaluate probabilistic predictions with uncertain observations. 

Furthermore, a common approach (e.g. for correlation measures) is to compare predictions with observations over a longer time period. In this contribution a paradigm shift away from this approach towards comparing predictions for each single time step (like years) will be presented. This view give new insights into the performance of the predictions and allows to come to new understandings of the reasons for advantages or disadvantages of specific predictions. 
The potential of ingrowth 226-Ra as a new dating tool for late Holocene carbonate deposits
Authors: Froeschmann Marie-Louise , Scholz Denis , Vonhof Hubert , Jochum Klaus Peter , Passchier Cees W. , Sürmelihindi Gül
Published: March 2020

One of the most commonly used methods for dating carbonate deposits, such as speleothems or calcareous sinter deposits, is the 230Th/U-disequilibrium method. With this approach, ages up to 500 ka can be obtained. However, especially for late Holocene samples, substantial detrital contamination may represent a major problem for radiometric dating. The high 232Th content, which is an indicator for the amount of detrital contamination, leads to elevated U/Th-ages and generally larger uncertainties, which limit the potential of the corresponding samples for paleoclimate reconstructions. Ingrowth 226Ra shows the potential to be used as an alternative dating method. In combination with Ba, U and Th, it is possible to date samples with ages up to 8 ka.

In general, there are three sources of 226Ra in carbonate samples. (i) excess 226Ra incorporated during deposition of the material, (ii) detrital material present in the carbonate, and (iii) ingrowth 226Ra produced by the radioactive decay of its parent 230Th. Due to the geochemically similar behavior of Ra and Ba, it is possible to correct for the amount of excess 226Ra. As for the 230Th/U-disequilibrium method, 232Th can be used to correct for detrital contamination.

To test our new method, we applied it to several calcareous sinter samples from different Roman aqueducts, which supplied drinking water to ancient cities such as Jerash or Cordoba . The separation of Ra, Ba, U and Th from the matrix of the samples is performed using a single aliquot of material and different ion exchange resins. Prior to the separation process, a calibrated mixed Ra-Ba-Th-U spike solution was added and equilibrated with the sample solution. The results are not only compared to model simulations for the new system, but also to ages obtained with the conventional 230Th/U-method.
Temperate, macrotidal, turbid estuarine behavior of mercury species. The case of the Loire river
Authors: Knœry Joel , Thomas Bastien , Brach-Papa Christophe , Briant Nicolas , Bruzac Sandrine , Chouvelon Tiphaine , Crochet Sylvette , Le Monier pauline , Ponzevera Emmanuel , Sireau Teddy
Published: March 2020

We have examined the distribution and spectiation mercury and trace metals under contrasted season, river flow conditions and tidal amplitudes with a series of  cruises taking place between 2012 and 2015. Our laboratory had alredy undertaken a similar study in the early 1990's. The latest data acquisition efforts are an opportunity to examine the changes that occurred within that time span for mercury and its species, and to discuss the causes of the observed changes. In particular, we will replace the  observations in the perspectives of environmental regulation, and of field and laboratory practices observed for environmental chemical characterization.

Early 1980's estuarine transects show total dissolved Hg levels near 5nM in the Loire river (Frenet, 1981). In the early 1990's, a careful and detailed study shows estuarine levels between 1 and 6pM (Coquery, 1994) with a strong dependency on the hydrological regime. New results confirm the riverine clevels in the low pM range. Concentrations decrease progressively during mixing with seawater and the oceanic end-member concentrations are near 0.5pM. Monitoring of mercury levels and speciation in the Loire river and the upper reaches of the estuary show that these Hg levels and species fluctuate with water flow and areal flooding upstream, AND on the history of that hydrological regime.
Modelling channelized fluid flow: failure physics and geological setting
Authors: Wang Hongliang , Yarushina Viktoriya , Podladchikov Yury
Published: March 2020

Fluid flow instability in deforming porous rock, commonly known as porosity waves, has been used to explain formation of seismic chimneys, one of the most important expressions for the localized fluid flow in the subsurface. Experiments show that volumetric deformation of rocks is strongly coupled with shear deformation, leading to shear-induced decompaction at low confining pressure and shear-enhanced compaction at higher confining pressure. Previous studies introduce a weakening factor of R for bulk viscosity in the viscous deforming regime. While it has successfully reproduced the channelized fluid flow in numerical models, it cannot investigate the effect of shear deformation. More controversially, negative effective pressure (Pt-Pf) is required for the channel formation. Here, we develop a viscoplastic rheology that takes into account effects of shear stress and plastic failure on the volumetric deformation, consistent with experimental data. A dilation pressure is naturally introduced through viscoplastic strain-rate when plastic failure occurs under high fluid pressure and shear stress condition. Our model results show that this new rheology can produce channelized fluid flow without negative effective pressure in the model.

In order to apply our models into real geological setting, we test the effects of reservoir properties, geological layering, transport properties of the layers and faults.  Our results show that fluid channel initiates at local topography highs in the reservoir and a high-permeability fault can also trigger the initiation of fluid channels. Fluid channels can have different length and time scales in different layers, depending on bulk viscosity and permeability of the layers.
The role of plant traits in shaping fire regimes in different ecosystems across the world
Authors: Baudena Mara , Diaz-Sierra Rubén , Provenzale Antonello , Sweeney Luke , Magnani Marta
Published: March 2020

Fire is an important disturbance process, having significant socio-economic consequences on the one hand, while fulfilling a vital ecological role on the other. Across fire-prone ecosystems, different fire regimes can be found, reflecting a combination of climatic factors and of different plant species characteristics. Ecosystem flammability and fuel load are the most evident and well-studied aspects of fire regime, with only recently attention being devoted to plant traits associated with fire adaptation and post-fire response. The aim of this research is to understand the role that plant traits have in driving fire regimes in different fire-prone ecosystems across the world. A mathematical, mechanistic model was developed representing vegetation dynamics, including stochastic fires and different plant fire-responses. We observe that differences in combinations of plant traits are an important factor in determining alternative ecological states. This is driven by differences in how plants determine fire occurrence and in relation to competition between plant species. Differing plant communities under the same climatic conditions can occur when the most competitive plant types do not have a strong resistance to fires, leading to different ecological and fire regime states for example in some tropical savannas and forests, or in Boreal forests. Conversely, when the dominant plant type has a very strong, post-fire response (at individual level), as e.g. in Mediterranean forests, only one ecological state is possible. This research can help improving understanding of changes in fire regime in the future to assist in fire management efforts, and underlines the importance of including plant fire-responses when modelling fire ecosystems under climate-change scenarios.
Integrating and assessing Arctic glacier thickness data into Glacier Thickness Database (GlaThiDa) Version 3.0
Authors: Welty Ethan , Navarro Francisco , Fürst Johannes , Gärtner-Roer Isabelle , Naegeli Kathrin , Landmann Johannes , Huss Matthias , Knecht Thomas , Machguth Horst , Zemp Michael
Published: March 2020

GlaThiDa is an internationally collected, standardized dataset of glacier thickness from in-situ and remotely sensed observations, based on data submissions, literature review, and airborne data from NASA's Operation IceBridge. GlaThiDa is a contribution to the working group on ‘glacier ice thickness estimation’ formed under the auspices of the International Association of Cryospheric Sciences (IACS). The database is hosted by the World Glacier Monitoring Service (WGMS). GlaThiDa is structured in three data tables of different levels of detail, which are linked together by a unique identifier for each glacier survey. The first table (T) is the overview table containing information on the location and area of the surveyed glacier, interpolated mean and maximum glacier-wide thickness and their reported uncertainties, the survey method and related information, as well as investigator names and source of the data. The second table (TT) includes mean and maximum ice thickness interpolated over surface elevation bands. The third table (TTT) contains the original point measurements, including spatial coordinates, surface elevation, and ice thickness. GlaThiDa was first released in 2014 (version 1.0) and first updated in 2016 (version 2.1). Version 3.0 was released in 2019. In addition to several technical improvements, nearly 3 600 ice-thickness surveys have been added, for a total of 5 181. Most of the new data are for Arctic glaciers, and some of these were collected for the H2020 INTAROS project. Moreover, GlaThiDa was assessed as a core component of the existing Arctic observing system in INTAROS Work Package 2.1 (an assessment of existing Arctic observational capacity and remaining gaps with respect to stakeholders needs). GlaThiDa has great potential as a reference dataset for calibrating and validating regional and global glacier volume estimates.
Seawater intrusion dynamic at the Casetta farmland (Venice). Characterization using HYDRUS-1D
Authors: Finco Greta , Zancanaro Ester , Teatini Pietro , Morari Francesco
Published: March 2020

Soil and groundwater salinization due to seawater intrusion is among the most important problems in coastal farmlands. Inverse estimation of unsaturated soil hydraulic and solute transport properties represents a fundamental step to understand saltwater intrusion dynamics. A three-year study was conducted in a maize field bounding the southern Venice Lagoon. Volumetric water content θ, soil matric potential ψ, and apparent electrical conductivity (ECa) were monitored hourly by five automatic monitoring stations at four depths (0.1, 0.3, 0.5 and 0.7 m). Groundwater electrical conductivity (EC) and depth to the water table were measured in five wells. In addition, soil water and groundwater samples were collected and analyzed to determine the chemical composition. Soil hydraulic parameters for the van Genuchten-Mualen equations were determined using the inverse method in Hydrus-1D. The water flow was modelled based on the daily averages of θ at the four depths and the θ values measured in the lab at selected ψ on undisturbed soil cores extracted from the five monitoring stations. Precipitation, crop transpiration, soil evaporation and depth to the water table were used as time-variable boundary conditions. Root water uptake was estimated by using Feddes model. Finally, the major ion chemistry module of HYDRUS-1D was used to model solute transport and root water uptake reduction due to osmotic stress. The use of HYDRUS-1D to understand saltwater dynamics would enable the developing of mitigation strategies to limit its detrimental effect on farmland productivity and groundwater quality.
Long-term Changes in the Surface Area in the Surroundings of the Open-cast Brown Coal Mine in Bełchatów (Poland)
Authors: Bugajska Natalia , Milczarek Wojciech , Kopeć Anna , Głąbicki Dariusz
Published: March 2020

Satellite radar interferometry, in particular time series techniques, allow to monitor the activity of the surface of vast areas, making them a complement and alternative to traditional geodetic methods, the use of which in such areas is often associated with significant restrictions. The above-mentioned areas definitely include open-cast mines, among others the analyzed Bełchatów Brown Coal Mine (Poland).
During the studies, 216 satellite images acquired from the Sentinel-1A and Sentinel-1B satellites (path 175) for the period from October 17, 2014 to June 11, 2019 were used. Due to the fact that the research area was on two adjacent stages, it was necessary to combine data for the correct performance of the calculation process. The use of the SBInSAR imaging processing algorithm allowed to generate 839 interferograms carrying information about the difference in interferometric phases between pairs of images which satisfy the condition of the boundary size of the spatial and temporal base. As a consequence, it allowed to determine the displacements in the direction of the electromagnetic beam LOS (Line of Sight) that occurred in the mining area during this period.
Based on the carried out calculations, significant activity of the area around the open-pit mine was perceived. Dumping ground were analyzed - external Szczerców Fields and internal Bełchatów Fields, as well as excavations where mineral extraction is currently taking place. Continuous deformations (depressions and uplifts) associated with intensively conducted mining exploitation and complicated geological and mining conditions occurring in this area were observed (arrangement of rock layers, faults, the Dębina salt debris separating the Bełchatów Field from the Szczerców Field).
A global volcanic eruption source parameter database with application to determination of ashfall risk to infrastructure
Authors: Neuweiler Anna , Daniell James , Schaefer Andreas , Wenzel Friedemann
Published: March 2020

Volcanic eruption sequences are often very long in length, and can cause significant downtimes and damage to infrastructure. Over the course of the H2020 EURATOM NARSIS project (New Approach to Reactor Safety ImprovementS), a review of volcanic sources for Europe was undertaken including historical impacts, source parameters and potential events to impact nuclear facilities either directly or operationally.

The development of a volcano database of Eruption Source Parameters in order to estimate the tephra dispersal and its risk for the surrounding population and infrastructure is an important component for volcanic risk modelling.

Each eruption is unique with different Eruption Source Parameters (ESPs), depending on the volcano and its surrounding area. The aim of the project is to create a global volcano database including the ESPs. With the help of this database it is possible to generate a risk map of tephra dispersal for future volcanic eruptions. This map can be used to estimate the potential risk of tephra fall for the surrounding population and infrastructure (development of isopahcs).

The ESPs includes the plume height, the duration of the eruption, the volume, the mass and the grain-size distribution of the erupted material. Using local wind data it is possible to model an eruption and its range with open-source software packages, like Fall3D. A review of such open-source software packages has been undertaken. To get the ESPs of a volcano, which represent its typical eruptions, the eruption history of the volcano needs to be known. This is done using databases like the Smithsonian GVP, VOGRIPA and LaMEVE, as well as other reports and scientific articles.

The intended result is a volcano database containing 1547 volcanoes. The ESPs for each volcano will be given in ranges to be able to determine the minimal and maximal effects of an eruption. However, data of previous eruptions will not in all cases be able to be found for every volcano. For these volcanoes, assumptions based on the behaviour of similar volcanoes need to be made. This will then be combined with the socioeconomic impacts of historic eruptions as have been collected as part of the CATDAT Damaging Volcanic Eruptions Database, as well as a reanalysis of historical eruptions for ashfall.