bluuebunny/crossref_metadata_2025 huggingface dataset:
Disentangling drivers of historical river flood losses
Authors: Sauer Inga , Reese Ronja , Otto Christian , Willner Sven , Frieler Katja , Bresch David , Geiger Tobias
Published: March 2020

Recent studies of past changes in precipitation patterns suggest regionally varying but clearly detectable trends of global warming on physical flood indicators such as river discharge. Whether these trends are also visible in economic flood losses, has not yet been clearly answered, as changes in trends of damage records may be induced by either climatic or socio-economic drivers. In general, the socioeconomic impact of an extreme weather event is composed of three components: The hazard, the exposure of socioeconomic values to the event, and the vulnerabilities of the values, i.e., their propensity or predisposition to be adversely affected. In this work, we separate the historically observed trends in economic losses from river floods into the three contributions. We then quantify the effect of each driver on the overall change in economic losses from river floods between 1980 - 2010 for different world regions. In particular, this allows us to determine in which regions anthropogenic warming has already contributed to the observed trends in damages. We use flood depth as biophysical hazard indicator calculated by combining discharge simulations from 12 global hydrological models of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) model ensemble with the river-routing and flood inundation model CaMa-Flood. The hydrological models are driven by observed weather data and our simulations account for present-day protection standards from the FLOPROS database. Asset losses are estimated by combining gridded asset data with state-of-the-art flood damage functions translating flood depth to the fraction of affected assets employing the open-source socioeconomic impact modelling framework CLIMADA. Trends in modeled historical flood damages are then compared to observational damages by Munich Re’s NATCATService database in order to explain residual differences in trends by the three types of drivers. 

We first show that the method permits to reproduce the year-to-year variability observed damages on the regional level. We identify changes in exposure as the main driver of rising damage trends, but also observe significant - rising as well as declining - trends in flood hazards in several regions. Thus, effects of anthropogenic climate change that have already shown to unfold in discharge patterns, partly manifest already in economic damages, too. Residual trends in observed losses, that cannot be explained by changes in the hazard and the exposure alone, are caused by changes in vulnerability that can be well explained with trends in GDP per capita.  Mostly, rising regional income results in declining vulnerability to river floods, in particular in less developed world regions. However, we also find indications of maladaptation, i.e., in some regions, vulnerability increases with GDP per capita.
Measurement of soil particle-size distribution by the PARIO measurement system: lessons learned and comparison with two other measurement techniques
Authors: Nemes Attila , Angyal Anna , Mako Andras , Jacobsen Jan Erik , Herczeg Eszter
Published: March 2020

The PARIO system is a novel technique for the measurement of soil particle-size distribution. It is a computerized sedimentation-based system that will yield a quasi-continuous particle-size distribution curve. Given that it is semi-automated, continuous and sedimentation-based, this system promises to become a good and compatible alternative to the traditional pipette or hydrometer techniques. Through hundreds of measurements we have acquired practical operational knowledge that this poster will share with potential future users. We will also present quantitative information on the technique’s sensitivity to e.g. temperature shift or intermittent vibration during measurement. We also used a set of 45 soil samples of various texture from Norway to compare particle-size distribution measured by the PARIO system, the traditional pipette technique and laser diffractometry. We discuss measurement results as well as related sample-preparation aspects.
Early Comparison of OCO-3 XCO2 Measurements with TCCON
Authors: Kiel Matthaeus , Laughner Joshua , Eldering Annmarie , Fisher Brendan , Kurosu Thomas , Pavlick Ryan , Osterman Gergory , Nelson Robert , O'Dell Christopher , Somkuti Peter , Taylor Thomas , Roehl Coleen
Published: March 2020

The Orbiting Carbon Observatory-3 (OCO-3) was successfully launched on May 4, 2019 from Kennedy Space Center via a Space-X Falcon 9. One week later, the instrument was installed as an external payload on the International Space Station (ISS). OCO-3 extends NASA’s study of carbon and measures the dry-air mole fraction of column carbon dioxide (XCO2) in the Earth’s atmosphere from space.

These space-based measurements are compared to ground-based observations from the Total Carbon Column Observing Network (TCCON). TCCON is a global network of high-resolution ground-based Fourier Transform Spectrometers that records spectra of the sun in the near-infrared spectral region. From these spectra, accurate and precise column-averaged abundances of atmospheric constituents including CO2 are retrieved. TCCON data are tied to the WMO scale and serve as the link between calibrated surface in situ measurements and OCO-3 measurements.

OCO-3’s agile 2-D pointing mirror assembly (PMA) allows the instrument to stare at a TCCON station as it passes overhead - providing information about the quality, biases, and errors in the OCO-3 data. Here, we show early comparisons between the OCO-3 XCO2 dataset collected during target mode observations and coincident TCCON measurements and discuss site-dependent biases and its potential origins.
Solubility of metals in aerosol samples from Mount Etna during the EPL-REFLECT campaign
Authors: Giorio Chiara , D'Aronco Sara , Soldà Lidia , Giammanco Salvatore , La Spina Alessandro , Salerno Giuseppe , Donatucci Alessia , Caltabiano Tommaso , Sellitto Pasquale
Published: March 2020

Volcanoes emit a chemically complex cocktail of gases and aerosols into the atmosphere, which can affect Earth’s climate (1) and human health. The vast majority of volcanogenic fatalities involve the obvious thermal and physical injuries resulting from an eruption, but many of the emissions from volcanoes are toxic and include compounds such as sulfates and metals, which are known to disrupt biological systems (2). Yet, there is a lack of knowledge on the toxicity of compounds found in volcanic plumes and their fate in the atmosphere.

Research has focussed on the impacts of large-magnitude explosive eruptions. While emissions from many non-explosive eruptions are continuous and prolonged, their climatic and potential effects on human health have not been studied extensively. Once the plume disperses in the atmosphere, the aerosol particle components can mix and interact with oxidants and organic compounds present in the atmosphere. How these chemical components interact and how the interactions affect the Earth’s climate, particle toxicity and human health is largely unknown especially for trace metals.

In the framework of the EPL-REFLECT (Etna Plume Lab – near-source estimations of Radiative EFfects of voLcanic aErosols for Climate and air quality sTudies), a field campaign on Mount Etna was done in July 2019 in which samples of atmospheric aerosol were collected during non-explosive degassing activity. Samples were collected both at the crater and in a transect following the volcanic plume down slope to the closest inhabited areas. Samples were analysed for trace metals and organic compounds, including solubility tests (3) to assess how tropospheric processing of the aerosol affects metal bioavailability and potentially the toxicity of the aerosol.

 

(1) von Glasow, R. 2010. Atmospheric chemistry in volcanic plumes. Proceedings of the National Academy of Sciences, vol. 107, pp. 6594–6599., DOI: 10.1073/pnas.0913164107

(2) Weinstein, P., Horwell, C.J., Cook, A. 2013. Volcanic Emissions and Health. In: Essentials of Medical Geology, Springer Netherlands, Dordrecht, pp. 217–238., DOI: 10.1007/978-94-007-4375-5_10

(3) Tapparo, A., Di Marco, V., Badocco, D., D’Aronco, S., Soldà, L., Pastore, P., Mahon, B.M., Kalberer, M., Giorio, C. 2019. Formation of metal-organic ligand complexes affects solubility of metals in airborne particles at an urban site in the Po Valley. Chemosphere, in press., DOI: 10.1016/j.chemosphere.2019.125025
Above ground response of rainforest functional groups to experimental drought
Authors: Kübert Angelika , Kühnhammer Kathrin , Bamberger Ines , Daber Erik , De Leeuw Jason , Bailey Kinzey , Hu Jia , Ladd S. Nemiah , Meredith Laura , van Haren Joost , Beyer Matthias , Dubbert Maren , Werner Christiane
Published: March 2020

Functional group-specific water use strategies are vital in understanding plant performance under current and future global climate change related drought scenarios. Different functional groups have different strategies to regulate their above ground water use and loss in order to respond to drought stress. Here, we studied the ecohydrological response of a controlled rain forest system to a 10-week lasting experimental drought (Biosphere 2 Water, Atmosphere, and Life Dynamics, B2 WALD project). Using gas exchange chambers, we specifically investigated the response of the two main rain forest functional groups - three canopy tree species and two understory species - in their above ground water use efficiency. Rates and isotopic fluxes of transpiration, assimilation and night respiration were monitored in high temporal resolution. In combination with plant physiological information (i.e., leaf water potential) a complete picture of their above ground water use could be gained. We expect that the deep rooting canopy tree species will be able to keep their above ground water use constant while the shallow rooting understory species will have to adapt their water use efficiency to budget their water reserves and resources.
What role does tillage erosion play regarding landscape evolution of an intensively used hummocky landscape?
Authors: Öttl Lena Katharina , Fiener Peter , Wilken Florian , Sommer Michael
Published: March 2020

Hummocky landscapes under intensive arable use are substantially affected by erosion processes. Data from the Quillow catchment (size: 196 km2; mean annual precipitation: 500 mm) in North-East Germany are used to estimate landscape-scale water and tillage erosion with the model SPEROS-C. Recent results show that tillage erosion causes substantial soil redistribution that can distinctively exceed water erosion. In consequence, truncated soil profiles can be found on hilltops and steep slopes, whereas colluvial material is accumulated in depressions and along downslope field boarders. The resulting spatial variability of soil types with different properties and conditions is known to influence crop growth and leads to a highly variable biomass pattern in hummocky landscapes under highly mechanised arable cultivation.

The main goal of our study is to link tillage-induced erosion rates to landscape development at centennial time scales. By modelling the development of the hummocky moraine landscape of North-Eastern Germany, we explain the spatial distribution of the current soil erosion state. Furthermore, the soil erosion induced impact on crop biomass patterns and the redistribution of soil organic carbon since the beginning of human land use in this area is assessed. To address this goal, a new model component is implemented into SPEROS-C that iteratively rejuvenates topography backwards in time considering modelled erosion and deposition rates. Afterwards, modelling forward in time allows estimating carbon fluxes due to soil redistribution. Furthermore, the extent and location of truncated soils will be validated with historic aerial photographs at different time steps.

The benefits of implementing landscape development into SPEROS-C are that (i) an annual update of topography generates a more realistic soil erosion pattern, (ii) the current crop biomass pattern may be explained by erosion history, and (iii) estimates about the future development of crop yield patterns considering ongoing tillage practices can be drawn from a validated soil erosion and landscape development model.
Stromboli volcanic island as a source of tsunami hazard for the Tyrrhenian Sea
Authors: Zaniboni Filippo , Pagnoni Gianluca , Gallotti Glauco , Tinti Stefano , Armigliato Alberto
Published: March 2020

The recent paroxysmal crisis occurring on the island of Stromboli (Tyrrhenian Sea, Italy), manifesting into two main events during summer 2019 (3rd July and 28th August), renovated the attention on the possibility of tsunami generation induced by volcanic activity. The Stromboli edifice is characterized by the Sciara del Fuoco scar on its north-western flank channeling most of the material ejected from the crater to the sea.

In this area, in December 2002, two landslides (the first submarine, the second subaerial) triggered large waves affecting the whole coast of the island, causing severe damages but fortunately no casualties, due to the non-touristic period. The tsunami rapidly dissipated with distance, being observed in Panarea (20 km south-east of Stromboli), as is typical of non-seismic tsunamigenic sources. A similar occurrence during summer would have resulted into dramatic consequences, especially along the Stromboli coasts.

In this study, the tsunamigenic potential associated with destabilized mass along Stromboli flanks is evaluated by means of numerical, in-house developed, codes with the aim of providing insights on the tsunami hazard along the coasts of Stromboli, of the surrounding Aeolian archipelago and in general in a larger domain covering the southern coasts of Tyrrhenian Sea as well.
Climate risk score – a framework to quantify an insurance portfolio's exposure and contribution to climate change
Authors: Lüthi Samuel , Gloor Michael , Walz Michael
Published: March 2020

The (re)insurance industry is alarmed that trends resulting from changing climate extremes may not be correctly reflected in its models, which are typically calibrated on past data. However, depending on the region and the peril, these trends vary in direction, magnitude and confidence level. A climate risk score framework has been developed that allows to identify regions or insurance portfolios which are particularly exposed to the consequences of climatic changes. In addition, the score also highlights a portfolio's contribution to climate change which eventually translates into a transitional risk – the risks emerging from the transition to a low-carbon economy.

The climate risk score is based on several sub-scores which reflect expected changes in mean and extreme precipitation and temperature as well as in mean sea level rise. It is computed using data output from several CMIP5 models – the models that lay the data foundation of the recent IPCC reports. In addition, the Swiss Re proprietary storm surge zones as well as its pluvial and fluvial flood zones are incorporated, allowing for a risk view in high-resolution (30 m). The contribution to climate change is displayed qualitatively, based on the occupancy of the individual sites of the portfolio.

Using this framework, the climate risk exposure of individual insurance portfolios can be assessed over time, across different RCP scenarios, or against an overall market portfolio. These insights can amongst others be used to steer a portfolio, or to judge past and expected changes in portfolio profitability and may thus also influence underwriting decisions. This may be particularly relevant for portfolios that are exposed to so-called secondary perils, i.e. high-frequency loss events of low-to-medium severity. Furthermore, regions can be identified, where uncertainties are particularly high and a more in-depth analysis of existing models might be required.
Systematic underestimation of snow accumulation rate by stake measurements in central Antarctica
Authors: Ekaykin Alexey , Tebenkova Natalia , Lipenkov Vladimir , Veres Arina , Tchikhatchev Kirill , Richter Andreas
Published: March 2020

We demonstrate that the accumulation-stake measurements in central Antarctica systematically underestimate the value of the snow build-up due to the compaction of snow layer between the stake base and the snow surface. We have developed two methods to define the corresponding correction to the snow build-up measurements at the stake farm near Vostok station. The first method is based on "Sorge's law" to calculate the rate of thinning of the snow layers using the vertical snow density profile. The second method consists of direct instrumental measurements of this thinning in the field. We have also involved the data of other two independent methods to estimate the snow accumulation rate in the vicinity of Vostok - first, geodetic data on the rate of snow layer sinking and, second, glaciological data from snow pits. The most reliable estimate of the snow accumulation rate in this region is 2.26±0.10 g cm-2 year-1, that is 8±4 % higher than initial (not corrected) value from the accumulation-stake measurements.
Poleward shift in the Southern Ocean westerlies synchronous with the deglacial rise in atmospheric CO2
Authors: Gray William , Wills Robert , Michel Elisabeth , Kageyama Masa
Published: March 2020

The Southern Ocean westerly winds are hypothesised to play a key role in regulating atmospheric CO2 over glacial-interglacial cycles; constraints on the paleo-latitude of the westerly winds have, however, remained allusive.  Here we use changes in the spatial pattern of planktic foraminiferal ∂18O to track changes in the latitude of the Southern Ocean polar and subtropical fronts over the last deglaciation, which are closely tied to the position of the westerly winds. We find a ~5° equator-ward shift in the position of the fronts (and thus westerlies) during the last glacial maximum relative to their Holocene position. Our reconstruction shows the poleward shift in the westerlies over deglaciation closely mirrors the sub-millennial scale variability seen in the rise in atmospheric CO2. We propose that changes in the position of the westerly winds modulate CO2 via changes in the extent of Southern Ocean sea ice and circulation of the abyssal ocean. Using climate model simulations, we explore the possibility of a feedback loop by which these CO2/climatic changes may lead to further changes in the position of the westerly winds.
Global age of air spectrum from the earth surface to the upper troposphere and tropopause: a model study
Authors: Podglajen Aurelien , Charlesworth Edward , Ploeger Felix
Published: March 2020

Transport of air masses from the surface into the atmosphere occurs via a variety of processes (including clear-air turbulence, atmospheric convection and large-scale circulations), which entails a multitude of transport time scales. This complexity can be characterized in an atmospheric transport model by calculating the age of air spectrum (transit time distribution from the surface). Up to now, mainly the slow time scales of stratospheric and interhemispheric transport (>10 days) have thus been studied. Vertical transport through the troposphere, for which convection is the major player, has only been evaluated using a handful of measured compounds (Radon, CO2 and SF6). However, a wealth of chemically relevant species are affected by the detailed structure of the age spectrum. Recent work (Luo et al., 2018) have used this sensitivity in order to gain observational insights into the tropospheric age spectrum, calling for a comparison with models.

To that end, we derive upper tropospheric and tropopause age spectra in the EMAC (ECHAM/MESSy Atmospheric Chemistry) model using the Boundary Impulse Response (BIR) method. Because of the large range of time scales involved in tropospheric transport, which extend from tens of minutes (convective transport) to years (stratospheric intrusions), we rely on a suite of pulses with variable durations providing hourly resolution for short time scales (< 12 hours) and monthly for long ones (> 1 month). We first describe the age spectra obtained and their diurnal and seasonal variability. Then, we examine the transport properties from a few specific surface regions to the upper troposphere and stratosphere, with an emphasis on fast pathways from the tropical Western Pacific and on interhemispheric transport. Finally, we investigate the sensitivity of different transport pathways to changes in some of the available model parameterizations (convection) and to different set-ups (using nudging or not).
UAV and Spaceborne LiDAR Gives First Evidence of Peat Domes in the Congo Basin
Authors: Davenport Ian , McNicol Iain , Mitchard Edward , Lewis Simon , Hawthorne Donna , Dargie Greta , Bocko Yannick , Lawson Ian , Baird Andy , Page Susan , Suspense Ifo , Milongo Brice
Published: March 2020

The peatlands of the Cuvette Centrale depression in the Congo Basin store between 6.3 and 46.8 petagrams of carbon. To improve our understanding of the genesis, development and functioning of these peatlands, we need to know if their surface is domed. Past work using satellite-based instruments has established that if the peatland surface is domed, it is very shallow, below 2‑3 m over a distance of 26km. We used a laser altimeter mounted on an unmanned airborne vehicle (UAV) to measure peat surface elevation along two transects at the edges of a peatland  to centimetre accuracy, and combined the results with an analysis of local ICESat and ICESat-2 returns. The LiDAR elevations show an upward slope inwards from both edges, and the ICESat and ICESat-2 returns suggest a peak around 1.8 m  above the edges. This matches our expectations of a rainfed peatland and, combined with prior measurements of peat depth, indicates that this peatland formed in a 3 m-deep basin.
Assessing GlobWat model sensitivity to climate forcing
Authors: Abdollahi Banafsheh , Hut Rolf , van de Giesen Nick
Published: March 2020

Irrigation is crucial for sustaining food security for the growing population around the world. Irrigation affects the hydrological cycle both directly, during the process of water abstraction and irrigation, and indirectly, because of infrastructures that have been built in support of irrigation, such as canals, dams, reservoirs, and drainage systems. For evaluating the availability of freshwater resources in the light of growing food demand, modeling the global hydrological cycle is vital. The GlobWat model is one of the models that have been designed for large scale hydrological modeling, with a specific focus on considering irrigated agriculture water use. Both models’ underlying assumptions and the global input data sets used to feed the model could be sources of uncertainty in the output. One of the most challenging input data sets in global hydrological models is the climate input data set. There are several climate forcings available on a global scale like ERA5 and ERA-Interim. In this study, we assess the sensitivity of the GlobWat model to these climate forcing. Pre-processing climate data at a large scale used to be difficult. Recently, this has become much easier by data and scripts provided by eWaterCycle team at the eSience center, Amsterdam, The Netherlands. We will use eWaterCycle's freely available data sources for our assessment and then we will compare the model results with observed data at a local scale.
On doing Hydrology with Lions
Authors: Wagener Thorsten
Published: March 2020

Humanity has always been uncomfortable with knowledge gaps. When John Cabot left Bristol harbour in 1497 to find a new route to Asia, he was trying to fill one of those knowledge gaps. World maps available to him at the time seemingly described the world in great detail. However, when inspecting such maps more closely, one could see that much of this information were just drawings of lions and other monsters, reflecting areas that were actually unexplored. It is claimed that ancient mapmakers demarcated such unknown areas with the phrase HIC SUNT LEONES, "here be lions", suggesting that exploring such areas was dangerous and undesirable. But, less than a hundred years later, such maps had changed. They now revealed large areas of white space to reflect a lack of knowledge, thus inviting exploration to discover what was beyond the edge of current knowledge. Acknowledging the unknown became a scientific goal in itself.

Hydrology is rapidly developing into a global science where both mechanistic and data-based models assimilate global datasets to predict hydrologic behaviour across continental and even global domains. Model outputs showing global maps of hydrologic variables like streamflow, soil moisture or groundwater recharge have become increasingly common. However, such maps rarely contain information about where model predictions are made with more or less confidence. Where are models producing trustworthy information and where are we showing (hydrologic) lions? What are the reasons for variability in confidence that should be considered? How can we overcome these reasons? I will explore these questions with different examples drawn from large-scale hydrologic modelling.
RTView 1.0: a new software for High Rate GNSS data analysis and visualization in Real Time
Authors: Pandolfo Francesco , Mattia Mario , Rossi Massimo , Bruno Valentina
Published: March 2020

Volcano ground deformations needs hardware and software tools of high complexity related to the processing of raw GNSS data, filtering of outliers and spikes and clear visualization of displacements occurring in real time. In this project we developed a web application for high rate real time signals visualization from permanent GNSS  remote stations managed by INGV OE (Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo). Currently the new software tool is able to import GNSS data processed by some of the most important high rate real time software like GeoRTD® (owned by Geodetics), GNSS Spider® (Owned by Leica Geosystems) and RTKlib. The tool is based on the Grafana open source platform and InfluxDB open source database. Various dashboards have been configured to display time series of the North-East-Up coordinates to monitor single stations, to compare signals coming from different data sources and to display the displacement vectors on the map. We also applied a simple alghoritm for the detection of abnormal variations due to impending volcanic activity.This web interface is applied to different active Italian volcanoes as Etna (Sicily), Stromboli (Aeolian Islands) and Phlegrean Fields (Naples). We tested the performance of this software using as a case study the 24th December 2018 dike intrusion on the Etna volcano.
Modelling the impacts of cranberry farms on the hydrologic regimes of the Bécancour River watershed in Québec, Canada
Authors: Gumiere Silvio J. , Celicourt Paul , Lafond Jonathan , Rousseau Alain
Published: March 2020

The Bécancour River watershed, located half way between Montréal and Québec City in the Province of Québec (Canada) and covering a surface area of about 2600 km2, is dominated by forest in the upstream portion and agriculture in the downstream portion. The production of cranberries (Vaccinium macrocarpon) is an important feature of this watershed. This crop not only relies on abundant water resources for frost protection, soil moisture management, and harvest and winter flooding, but also on tiled drainage system which together impact the watershed hydrology and flow patterns.

This study aims at modelling the impacts of cranberry farms on the hydrologic regimes of the Bécancour River watershed in Québec, Canada. We dispose of groundwater level and soil tension data at the root zone from two distinct cranberry farms, meteorological data, Ground-penetrating radar (GPR) and stratigraphy data, and LIDAR data collected over a period of 5 years starting in 2014. We setup the hydrological model using the well-known finite-element-based model named FEFLOW to simulate the hydrological behavior of two cranberry farms in the watershed. The preliminary results are promising and demonstrate the potential of the model in a) depicting and understanding hydrological changes in the watershed and b) supporting decision-making regarding water resources management for agricultural production in the region.
Disaster diplomacy and planetary defense: a policy perspective on low probability events
Authors: Lindquist Eric
Published: March 2020

The characterization of near-Earth-objects (NEOs) with regard to physical attributes and potential risk presents a complex scientific challenge. The societal and policy risks and impacts are no less complex. If, in fact, humankind is finally at the stage where it can technically prevent or mitigate a catastrophic asteroid impact, through deflection or other physical means, the question remains as to whether or not humankind has the political will, and appropriate institutions, to do so. As such, planetary defense represents a unique opportunity to link public policy theory and disaster diplomacy with regard to a low probability/high risk problem. What challenges does this opportunity raise, and how should we look into this situation? The problems of NEOs, asteroids and planetary defense and the solutions prescribed to address them presents an interesting and unique challenge for public policy theory. David Morrison’s definition of the problem (2010) sets the diplomatic and policy stage…  “the potential exists for an impact catastrophe at any time, in any country, with little or no warning.” Current planetary defense policy approaches can be characterized into three areas:

1) Identification, characterization, and monitoring of objects and their potential threat. Creation of the concept of “planetary defense” which is a policy statement in itself, and the institutionalization of PD (NASA, ESA, UN, interagency working groups, universities).

2) Response (solution) type 1, or the determination and implementation of effective deflection or mitigation responses. The solution is more science and technology.

3) Response (solution) type 2, the traditional civil defense and natural hazard response, preparation and response activities.

Are NEOs scientific and technological problems to be “solved” through more research funding, decrease the uncertainty, or are they more of a traditional civil defense problem, global security problem, or even an opportunity for larger issues of the peaceful and legal use of space and the economic exploitation of space resources? Each of these definitions of the “problem” is connected to potential “solutions,” which compete for attention and resources with significant implications for disaster diplomacy and governance. This contribution will connect current disaster diplomacy thinking with our understanding of the policy challenges from low probability/high consequence disaster events.
Modeling wormhole formation in digital rock samples: the role of segmentation and permeability-porosity relationships
Authors: Sharma Rishabh Prakash , Cooper Max P. , Ladd Anthony J.C. , Szymczak Piotr
Published: March 2020

In this work we have investigated numerically the formation of channelised dissolution patterns, termed “wormholes”, using initial pore geometries generated from tomographic images of limestone cores. We have employed an OpenFOAM-based Darcy-scale numerical solver,  porousFoam, which combines a Darcy/Darcy-Brinkman flow solver and a reactive transport solver in an evolving pore space. Simulated geometries, of both final and intermediate steps, are compared to dissolution experiments on samples the initial pore geometry is generated from, with the same acid concentration and flow rate applied. 

The initial condition of porosity distribution is set from X-Ray Computed Microtomography (XCMT) images via three phase segmentation into macroporosity, microporosity, and grain regions. Porosity values for microporous regions are set using linear interpolation between pore and grain grayscale values [1]. The inlet boundary conditions of flow rate and acid concentration are set as in the dissolution experiment. To test the effect of the permeability-porosity constitutive relationship we have investigated several options including power laws of varying exponent, and the Carman-Kozeny relation. We have also analyzed the impact of using Darcy versus Darcy-Brinkman flow solvers. Despite a qualitatively similar appearance to experimental results, the simulated wormholes are usually significantly thicker than their experimental counterparts, a fact noted by other researchers as well [2]. We comment on possible reasons for this discrepancy and on the limitations of Darcy-scale solvers in general. Additionally, we find that higher exponents in the power law makes the numerical dissolution very sensitive to grayscale threshold values as a small variation in this value changes the path of the wormhole.

 

[1] Luquot, L., Rodriguez, O., and Gouze, P.: Experimental characterization of porosity structure and transport property changes in limestone undergoing different dissolution regimes, Transport Porous Med., 101, 507–532, 2014.

[2] Yue Hao, Megan Smith, Yelena Sholokhova, Susan Carroll, CO2-induced dissolution of low permeability carbonates. Part II: Numerical modeling of experiments, Advances in Water Resources, 62, 388-408, 2013 
Exploring Earth Science Applications using Word Embeddings
Authors: Koehl Derek , Davis Carson , Ramachandran Rahul , Nair Udaysankar , Maskey Manil
Published: March 2020

Word embedding are numeric representations of text which capture meanings and semantic relationships in text. Embeddings can be constructed using different methods such as One Hot encoding, Frequency-based or Prediction-based approaches. Prediction-based approaches such as  Word2Vec, can be used to generate word embeddings that can capture the underlying semantics and word relationships in a corpus. Word2Vec embeddings generated from domain specific corpus have been shown in studies to both predict relationships and augment word vectors to improve classifications. We describe results from two different experiments utilizing word embeddings for Earth science constructed from a corpus of over 20,000 journal papers using Word2Vec. 

The first experiment explores the analogy prediction performance of word embeddings built from the Earth science journal corpus and trained using domain-specific vocabulary. Our results demonstrate that the accuracy of domain-specific word embeddings in predicting Earth science analogy questions outperforms the ability of general corpus embedding to predict general analogy questions. While the results are as anticipated,  the substantial increase in accuracy, particularly in the lexicographical domain was encouraging. The results point to the need for developing a comprehensive Earth science analogy test set that covers the full breadth of lexicographical and encyclopedic categories for validating word embeddings.

The second experiment utilizes the word embeddings to augment metadata keyword classifications. Metadata describing NASA datasets have science keywords that are manually assigned which can lead to errors and inconsistencies. These science keywords are controlled vocabulary and are used to aid data discovery via faceted search and relevancy ranking. Given the small size of the number of metadata records with proper description and keywords, word embeddings were used for augmentation. A fully connected neural network was trained to suggest keywords given a description text. This approach provided the best accuracy at ~76% as compared to other methods tested.
Projected changes to Severe Thunderstorm environments as a result of 21st century warming from RegCM CORDEX-CORE simulations
Authors: Glazer Russell , Torres-Alavez José Abraham , Coppola Erika , Das Sushant , Ashfaq Moetasim , Sines Taleena
Published: March 2020

Dangerous weather related to severe thunderstorms including tornadoes, high-winds, and hail cause significant damage globally to life and property every year. Yet the impact on these storms from a warming climate remains a difficult task due to their transient nature. In this study we investigate changes in the large-scale environments in which severe thunderstorms form during 21st century warming (RCP2.6 and RCP8.5) in a group of RegCM CORDEX-CORE simulations. Severe potential is measured in terms of CAPE (Convective Available Potential Energy) and shear during the severe seasons in three regions which are known to currently be prone to severe hazards: North America, the southeastern coast of South America east of the Andes, and eastern India and Bangladesh. In every region environments supportive for severe thunderstorms are increasing during the warm season months in both RCP2.6 and RCP8.5 during the 21st century. The number of days supportive for severe thunderstorms increases by several days per season over the vast majority of each region by the end of the century. In the case of RCP2.6, where greenhouse gas forcing is relatively weak compared to RCP8.5, there is still a consistent positive trend in the impact on severe days. The simulations using RCP8.5 forcing show large changes to the annual cycle of severe weather as well as the number of days supportive for severe weather per season. In some regions, like for example Northern Argentina along the Andes mountains, the number of days with severe conditions present increases by nearly 100% by the end of the century. Analyzing the CAPE and shear trends during the 21st century we find seasonal and regionally specific changes driving the increased severe potential. 21st century surface warming is clearly driving a robust increase in CAPE in all regions, however poleward displacement of vertical shear in the future leads to the movement of severe environments over North America and South America. The results found here relate that severe impacts in the future cannot be generalized globally, and that regionally specific changes in vertical shear may drive future movement of regions prone to severe weather.
Precision Lightning Imaging with LOFAR
Authors: Scholten Olaf , Hare Brian , Pel Alex , Bonardi Antonio , Buitink Stijn , Corstanje Arthur , Falcke Heino , Huege Tim , Hoerandel Joerg , Krampah Godwin , Mitra Pragati , Mulrey Katie , Nelles Anna , Pandya Hershal , Rachen Joerg , Rossetto Laura , Trinh Gia , Veen, ter Sander , Winchen Tobias
Published: March 2020

We report on the improvements of our lightning imaging technique over what was reported in Hare2019, where we map lightning in 3D using timing obtained from the cross-correlation of the signals from antenna pairs in broadband VHF (30 — 80 MHZ). We use the infrastructure offered by LOFAR (LOw Frequency Array), a software radio telescope.

The infrastructure of LOFAR allows us to use a large number of simple dual-polarized dipole antennas arranged in stations of 48 antennas with a diameter of about 60m. We limit ourselves to the use of the Dutch stations only, which gives us baselines of up to 100 km. The data are sampled at 200 MHz giving 5 nanoseconds time between samples. We use LOFAR in the mode where it saves the full time-series spectra for five seconds for every antenna in the array. Upon a trigger, the data for all Dutch stations is stored for later off-line processing.

In imaging a flash our bottleneck is to handle the confusion limit. Because of the high density of sources, pulses that are detected in one time-order in the first antenna may have changed order in a second that is at an appreciable distance from the first. The pulse density where this problem surfaces depends on the imaging technique. In our new imaging method we use an approach inspired by the Kalman-filter technique. In the presentation the new technique will be explained. This allows us to obtain a larger number of located sources as compared to the approach used in Hare2019 (sometimes as much as three times as many) which allows for a more detailed analysis of small structures seen in lightning.

To show the strength of the new technique we show some images of positive and negative leader development as well as a return stroke.

 

Hare2019:  B. Hare et al., Nature 568, 360–363 (2019).
Kinematic restoration of the southern North Atlantic and the Alpine Tethys during the Mesozoic
Authors: Frasca Gianluca , Manatschal Gianreto , Cadenas Martínez Patricia
Published: March 2020

Continental rifting preceding stable seafloor spreading is characterized by a multistage evolution during lithosphere extension. Wide regions of exhumed mantle contain linear magnetic anomalies with a strongly debated nature and origin. Contrasting information used to set up dynamic plate models has resulted in a plethora of alternative interpretations. Structural and stratigraphic records at plate boundaries show indeed variable degree of discrepancies with what expected from computed plate motions during rifting stages. The definition of robust spatial and temporal kinematic constraints using combined offshore and onshore approaches represents a major challenge to unravel rifted margins evolution.   
 
In this study, we address the problem outlined above using the Mesozoic southern North Atlantic and the Alpine Tethys, west and east of the Iberian plate, as a natural laboratory. The two systems are part of the same Africa-Europe kinematic framework and record distinctive Mesozoic rift events and a subsequent Tertiary compression. While in the southern North Atlantic the kinematic framework is still preserved, in the Alpine Tethys, subsequent subduction/collision erased the paleogeographic framework. The study area is among the best investigated but also most debated geological domains on the globe.

In our analysis we (1) integrate rift domains in plate kinematic models and re-consider the nature of the magnetic anomaly J in the southern N-Atlantic; (2) discuss the results of recent studies in the northern part of the Iberian plate; and (3) show new data from the Alpine Tethys realm (Central European Alps and Southern Apennines). We discuss the implications of these observations for the geometry of the rift systems developed around Iberia.

Our robust data network radically reduces the range of possible kinematic solutions. We reconstruct thus the position of Iberia and Adria relative to Europe and Africa and we evaluate the kinematic evolution and the width of the southern North Atlantic and the Alpine Tethys domains during the Mesozoic. The analysis emphasizes (1) the stepping geometry of the plate boundary for the Atlantic-Tethys interaction, (2) the strong partitioning of deformation in time and space, and (3) the large-scale pattern of coeval compression and extension along the Africa-Europe diffuse plate boundary region.
The Effects of Cracks and Fluids on Post-Seismic Healing
Authors: Malcolm Alison , Khajehpour Tadavani Somayeh , Poduska Kristin
Published: March 2020

It is now well established that large seismic events change the surrounding velocities, and that these velocities slowly recover over time.  Precisely which mechanisms control the recovery process are less well understood.  We present the results of laboratory experiments to better characterise what properties of the underlying material control the recovery process.  We do this by mixing two waves, one which perturbs the velocity of the sample (as an earthquake does in field data) and one which senses the change in velocity (as in changing noise correlations).  This is an inherently nonlinear experiment as we mix two waves and measure the effects of this wave mixing.  Within our experiments, we vary the properties of the samples to understand which are most important in controlling the nonlinear response.  We focus on two mechanisms.  The first is fractures and how changes in fracture properties change the nonlinear response.  The second is fluids, in particular the effect of low saturations on the nonlinear response.  By changing the fluids and fractures we can turn on and off the nonlinear mechanism, helping us to move toward a better understanding of the underlying mechanisms of these wave-wave interactions.
Changes in seasonal snowpack in mountain catchments in Czechia
Authors: Nedelcev Ondrej , Jenicek Michal
Published: March 2020

Seasonal snowpack is an important part of the water cycle and it has a large influence on runoff regime in mountain catchments of Central Europe. However, snow water equivalent (SWE) is decreasing in many mountain regions over the last decades and spring snowmelt occurs earlier in the year. This study aimed 1) to analyse long-term changes and trends in selected snowpack characteristics, such as SWE, snow cover duration, snowmelt onset and melt-out in 40 mountain catchments in Czechia in the period 1965–2014 and 2) to relate the detected changes to changes in air temperature and snowfall fraction at different elevations. Since the availability of time series of measured SWE at a catchment scale is limited, a conceptual semi-distributed hydrological model HBV-light was used to simulate daily SWE for defined elevation zones. Besides SWE, the model simulated other water balance components, such as runoff, soil moisture and groundwater recharge. The integrated multi-variable model calibration procedure was used to calibrate the model. Both observed runoff and SWE were used for evaluation of the model performance. Seasonal and monthly mean of SWE, as well as snow cover duration, snowmelt onset, snowmelt rates and melt-out were calculated for individual catchments and elevation zones. The non-parametric Mann-Kendall test was used to detect potential trends in simulated time series. The results showed significant decreasing trends in snowfall fraction for all catchments and elevations in the study period mostly due to an increase in air temperature. This resulted in a decrease in snow storages in most of catchments, especially in western parts of Czechia. However, a lot of regional differences exists and no trends in SWE were detected in some catchments. Decreasing trends in snow cover duration were detected as well, mostly because of earlier snowmelt onset and melt-out.