bluuebunny/crossref_metadata_2025 huggingface dataset:
Disentailing Sources of Future Uncertainties for Water Management Policies in a Subtropical Water System.
Authors: Amaranto Alessandro , Giuliani Matteo , Chiarelli Davide Danilo , Rulli Maria Cristina , Juizo Dinis , Castelletti Andrea
Published: March 2020

Changing climate, growing population, and urbanization are likely to exacerbate the competition for water resources in the coming years, and to challenge the effectiveness of water management policies. In this rapidly evolving multi-stakeholder context, it is crucial to explore the sensitivity of water supply strategies to deeply uncertain climatic and socio-economic forcings, fostering the identification of policies that integrate optimality and low vulnerability against likely adverse future conditions. Here, we propose an integrated framework combining optimization, sensitivity and uncertainty analysis to retrieve the main sources of vulnerability to water management strategies across a multidimensional objective space. Our framework is tested in the Umbeluzi river, Mozambique, operated to meet three conflicting objectives: the water demand in the city of Maputo, hydropower production, and irrigation supply. Rapid urbanization, economic growth and water development plans mark the Umbeluzi as archetypal of most river basin in developing countries. The main sources of uncertainty we consider are: the projected increase in water demand following urbanization and irrigation development in the area; the magnitude of streamflow depletion due to climate change; and the completion date of the greater Maputo water supply expansion project. The optimization approach is based on Evolutionary Multi-Objective Direct Policy Search (EMODPS), while the sensitivity and uncertainty analysis are founded on the PAWN and the GLUE methods, respectively. Numerical results show that, while socio-economic and infrastructure are equally important for compromise solutions, climate becomes the most influential factor for asymmetric tradeoffs.
Characterization of Soil Organic Matter along an elevation gradient at Stelvio Pass (Italian Alps).
Authors: Zangrando Roberta , Villoslada Hidalgo Maria del Carmen , Turetta Clara , Cannone Nicoletta , Malfasi Francesco , Onofri Silvano
Published: March 2020

Climate Change (CC) has evident impacts on the biotic and abiotic components of ecosystems.

Soil is the third largest reservoir of carbon, next to the lithosphere and the oceans, and stores approximately 1500 Gt in the top1 m depth.  Even small changes in soil C stocks could have a vast impact on atmospheric CO2 concentration. Elevated surface temperature can substantially affect global C budgets and produce positive or negative feedbacks to climate change. Therefore, understanding the response of soil organic carbon (SOC) stocks to warming is of critical importance to evaluate the feedbacks between terrestrial C cycle and climate change.

In comparison to other ecosystems, the areas at high altitudes and latitudes are the most vulnerable. In permafrost areas of the Northern Hemisphere the CC has already determined an increase in greenhouse gas emissions, shrub vegetation and variation in the composition of microbial communities. While numerous studies have been performed in Arctic, much less numerous are available for high altitude areas. These areas are a quarter of the emerged lands  and have suffered strong impacts from the CC. Mountain permafrost makes up 14% of global permafrost, stores large quantities of organic carbon (SOC), and can release large quantities of CO2 due to climate change. However, permafrost contribution to the IPCC global budget has not yet been correctly quantified, in particular for ecosystems of prairie and shrubland, which alone could incorporate over 80Pg of C between soil and biomass. In the last decades, the plant component has undergone migration of species to higher altitudes, expansion of shrubs, variations in floristic composition and dominance, variations in area distribution. The expansion of the shrubs accelerates the regression of alpine meadows and snow valleys.

The sampling activities have been carried out in July and September, from September 2017 to July 2019 in an area near Stelvio Pass (2,758 m a.s.l.) (Italian Central-Eastern Alps) along an altitude gradient.   Two sampling sites located at 2600 m a.s.l. and 2200 m a.s.l. in altitude, corresponding to about 3° C difference in the average annual air temperature were chosen. At the 2600 m site, warming experiments using open-top chambers (OTCs) to investigate how climate warming affects SOC were performed.

In order to characterize the SOM (Soil Organic Matter), Total carbon (TC), Organic carbon (OC), Total Nitrogen (TN) and Dissolved Organic Carbon (DOC) were determined in soils. TC and TN were determined in biomass. In both soils and biomass were analyzed to quantify the distribution of stable isotopes of C and N, δ13C and δ15N.
Was Zechstein basin in Poland just large “hole in the ground”? – new extensional model based on reinterpreted regional seismic data
Authors: Krzywiec Piotr , Peryt Tadeusz M. , Kiersnowski Hubert
Published: March 2020

Syntectonic growth strata in extensional settings are characterized by gross divergent geometries towards the master normal faults. Similar depositional patterns might be expected for evaporitic successions deposited during active extension although for salt-rich systems it might be very difficult to discern initial syn-tectonic depositional thickness variations from those caused by syn-depositional or early post-depositional halokinetic flow. Evaporites can be also passively infilling accommodation space that was created before their deposition either by tectonics or by erosion. Re-evaluation of regional coverage of seismic data from the Polish Basin provided evidences that, contrary to previous views, formation of Zechstein (Wuchiapingian – Changshingian) evaporites was significantly controlled by active extension. This sedimentary basin was located within the eastern periphery of the large epicontinental Permian-Mesozoic Central European Basin System and was filled with several kilometers of siliciclastics and carbonates, and thick Zechstein evaporites. Its axial part, the Mid-Polish Trough, characterized by the thickest Permo-Mesozoic sedimentary cover and developed partly above the Teisseyre–Tornquist Zone, underwent substantial Late Cretaceous–Paleogene inversion and currently forms a large regional anticlinal structure referred to as the Mid-Polish Swell. Some previous models of deposition of Zechstein evaporites assumed that evaporation started after catastrophic flooding of vast paleo-topographic depression (“hole in the ground” model). Regional coverage of seismic data was used to map major sub-Zechstein fault network that were responsible for crustal extension during development of the Polish Basin and were reactivated as reverse fault zones during its regional Late Cretaceous – Paleogene inversion. Those sub-Zechstein fault zones are often associated with locally increased thickness of Zechstein evaporites (salt pillows). It could be shown that such thickness increase could be in turn associated with gradual thickness increase of particular Zechstein cyclothems towards sub-Zechstein fault zones. All those observations were used to construct regional model of the Zechstein basin that was controlled by regional extension. As a consequence, Zechstein evaporites deposited within the axial part of the basin have been partly reinterpreted as growth strata related to active basement extensional tectonics.
Biogeomorphic modeling: how to account for subgrid-scale interactions between hydrodynamics and vegetation patches
Authors: Gourgue Olivier , van Belzen Jim , Schwarz Christian , Bouma Tjeerd J. , van de Koppel Johan , Temmerman Stijn
Published: March 2020

Interactions between water flow and patchy vegetation are governing the functioning of many ecosystems, such as river beds, floodplains, wetlands, salt marshes, mangroves and seagrass meadows. However, numerical models that simulate those interactions explicitly, including at the patch-scale (that is, at resolutions below a m²), together with their far-reaching geomorphological and ecological consequences at the landscape-scale (that is, for domain sizes of several km²), are still very computationally demanding. In this communication, we will present a novel efficient technique to incorporate biogeomorphic feedbacks across multiple spatial scales (from below a m2 to several km2) in biogeomorphic models. Our new methodology is based on the mathematical concept of convolution, allowing to spatially refine coarse-resolution (order of meters) hydrodynamic simulations of flow velocity fields around fine-resolution (order of dm) patchy vegetation patterns. We will demonstrate the power of our new method, by comparing our results with reference fine-resolution (order of cm) hydrodynamic model runs, which themselves are calibrated against flume measurements. We will show that our new model approach enables to refine a coarser-resolution hydrodynamic model, by resolving subgrid-scale fine-resolution flow velocity patterns within and around patchy vegetation distributions. With simple example cases, we will show evidence that our novel approach can substantially improve the representation of important processes in current biogeomorphic models, such as subgrid-scale effects on sediment transport and vegetation growth. Finally, we will demonstrate that our convolution method is an important step forward towards more computationally efficient multiscale biogeomorphic modeling, as compared with what is possible to date.
ICESat-2 Precision Orbit Determination Performance
Authors: Thomas Taylor , Luthcke Scott , Pennington Teresa , Nicholas Joseph , Rowlands David , Rebold Timothy
Published: March 2020

The Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) mission launched on September 15th, 2018, with the primary goal of measuring ice sheet topographic change. The fundamental measurement used to achieve mission science objectives is the geolocation of individual photon bounce points. Geolocation is computed as a function of three complex measurements: (1) the position of the laser altimeter instrument in inertial space, (2) the pointing of each of the six individual laser beams in inertial space, and (3) the photon event round trip travel time observation measured by the Advanced Topographic Laser Altimeter System (ATLAS) instrument. ICESat-2 Precision Orbit Determination (POD) is responsible for computing the first of these; the precise position of the laser altimeter instrument.

ICESat-2 carries two identical on-board GPS receivers, both manufactured by RUAG Space. Tracking data collected by GPS receiver #1 is used as the primary data source for generating POD solutions. POD is performed using GEODYN, NASA Goddard Space Flight Center’s state-of-the-art orbit determination and geodetic parameter estimation software, and a reduced-dynamic solution strategy is employed. The GPS-based POD solutions are calibrated and validated using independent Satellite Laser Ranging (SLR) data from ground-based tracking stations.

ICESat-2 mission requirements state that the POD solutions must have a one-sigma radial accuracy of 3 cm over a 24-hour time interval. Here we show that early mission ICESat-2 POD performance is exceeding mission requirements. We describe in-depth the ICESat-2 spacecraft macro-model, used for non-conservative force modeling, and the results from tuning of the associated parameters. Lastly, we show the iterated GPS receiver antenna phase center variation map solution and assess its impact on POD performance.
Practical work in middle school Geology: Sand analysis lab
Authors: Ferreira Sílvia
Published: March 2020

The work presented in the poster is focused on the analysis of different sand samples in laboratory activities, at the level of middle school Portuguese science education. The role of practical work in offering students the opportunity to experience the process of scientific investigation is one of the arguments for practical work in science education. Students are expected to both learn scientific knowledge and mobilize science process skills whenever they are doing practical activities. Practical work has an important role in helping students to develop links between observations and ideas and to develop students’ understanding of science processes.

In sand analysis lab activity the students studied different sand samples under magnification and made observations on the sand grains size, sorting, shape, and composition. The differences in sand samples were related by the students to the depositional environments. For instance, the average size of the sand particles reflects both the strength of the current that carried them and the sizes of the crystals eroded from the parent rock. The range and relative abundance of the various sizes are also significant. The shapes of sand grains can also be important clues to their origin. Sand grains are rounded by abrasion as grains are knocked together during transport. For that reason, angular grains usually imply short distances of transportation. From the composition of sands, it is also possible to deduce the nature of the source areas that were eroded to produce the sand grains. The poster gives some examples of the observations of sand samples, in order to make clear the procedures and the discussion followed in the classroom.

The activity presented also intended to promote the development of science process skills with different levels of complexity. The science process skills are considered to be ways of thinking more directly involved in scientific research, such as observing, measuring, predicting, formulating problems and hypotheses, controlling variables and, interpreting data. These aspects are discussed in the poster and some examples of science process skills are given.
Probabilistic Machine Learning in Structural Geology
Authors: de la Varga Miguel , Wellmann Florian
Published: March 2020

As the number of underground activities increase, the need for better understanding of the geospatial properties become more and more essential for correct engineering designs and optimal decision making. However, gathering subsurface data is still an extremely costly and imprecise endeavour. Geological modelling has played a crucial role for years helping to understand and correlate the complex geometries encountered underground but single deterministic models fail to capture all possible configurations given the limited data. Probabilistic machine learning allows to integrate domain knowledge and observations of the physical world on a rigorous and consistent manner. Inferences to the probabilistic model implements an automatic learning-from-observations process.

 

In this work, we show how by embedding state-of-the-art implicit interpolants into probabilistic frameworks, we can integrate the information of distinct data sets in one single common earth model. We will present results from a minimal working example to introduce Bayesian statistics, to full 3-D probabilistic inversions. All the models used for this demonstration are implemented in the open-source library GemPy ( www.gempy.org) allowing full reproducibility of the results.

 
Unravelling the complex interplay between drought and conflict
Authors: Wanders Niko , von Uexkull Nina , Buhaug Halvard , di Baldassarre Giulianno
Published: March 2020

Climate change will likely exacerbate droughts, increase regional water demands and affect agricultural yields. In addition, projected population growth combined with lack of  ‘good’ governance is likely to enhance the negative impacts of droughts and crop failure in the future as agriculture increasingly expands onto marginal lands. There is a global concern about these trends, because crop failure, droughts, increasing pressure on suitable agricultural land and rangeland for livestock, and changes and quality of governance can also increase the risk of conflict and (organized) violence.

In this presentation we explore the strength and impact of the climate-conflict trap., We use historical drought simulations and future drought projections to study the link between conflict and drought. Conflict data are taken from the Uppsala Conflict Data Program and combined with hydrological simulations from the global hydrological model PCR-GLOBWB.

The results show that drought occurrence is expected to increase under all climate scenarios, with stronger impacts for the higher emission scenarios.  On the other hand, at the global scale conflicts are likely to reduce as increased economic wealth compensates for the increased climate vulnerability.

This work helps us to better understand the interplay between the natural hydrological system and society. To better understand unsustainable and potentially devastating pathways for the coming decades, we have the greater aim to start unravelling the complex dynamics between changes in drought, society and risk of conflicts.
Solidification timescale for the Dufek Intrusion, Antarctica determined by U-Pb zircon ages
Authors: VanTongeren Jill , Taylor Aidan , Schoene Blair
Published: March 2020

The 8-9 km thick Dufek layered mafic intrusion of Antarctica was emplaced at approximately 182 Ma associated with the Ferrar dolerites and the breakup of the supercontinent Gondwana.  It is rivaled in thickness only by the Bushveld Complex of South Africa and shows a similar progression in mineral compositions all the way to the uppermost contact with an overlying granophyre layer.  This progression in mineral composition suggests that it crystallized from the bottom to the top and did not form an upper solidification front (a.k.a., Upper Border Series) typical of smaller intrusions such as the Skaergaard Intrusion.  Unlike the Bushveld Complex, however, the Dufek Intrusion is exposed in only two ~1.8 km thick sections: the lowermost Dufek Massif, and the uppermost Forrestal Range, which are separated from one another by a ~50km wide snowfield.  The remainder of the stratigraphy is inferred from geophysics, evolution of mineral compositions, and projection of the dip of the layering through the snowfield. 

 

            We obtained precise CA-ID-TIMS U-Pb zircon ages from samples from the Dufek Massif and Forrestal Range in order to determine the timescale of solidification of a large layered mafic intrusion.  What we found is surprising - zircons from the bottom of the intrusion record younger ages than those from the top of the intrusion.  Two samples from the Dufek Massif have zircon U-Pb ages of 182.441±0.048 Ma and 182.496±0.057 Ma; whereas three samples from the Forrestal Range have zircon U-Pb ages of 182.601±0.064 Ma, 182.660±0.10 Ma, 182.78±0.21 Ma.  Thus, the lower section of the Dufek Intrusion solidified approximately 160,000 years after the upper.  We explore two possibilities for this reverse-age stratigraphy, (1) that the ages reflect the solidification of interstitial melt in a single magma chamber cooling from the top down, or (2) that the Dufek Massif and Forrestal Range are two separate magma chambers that are not connected at depth.  Our results have implications for the stratigraphic thickness estimates of the Dufek Intrusion as well as the duration of magmatism associated with continental breakup.

 

 
GHIRAF: closing the gap between global models and locally-actionable information
Authors: McCall Robert , Diermanse Ferdinand , Twigt Daniel , Quataert Ellen , Roelvink Floortje
Published: March 2020

The impact of extreme weather events on coastal areas around the world is set to increase in the future, both through sea level rise, climate change (increasing storm intensity, rainfall and droughts) and continued development and investment in hazard-prone deltaic and coastal environments. Given the changing natural and socio-economic environment, accurate predictions of current and future risk are becoming increasingly important world-wide to mitigate risks. Recent advances in computational power (e.g., cloud-computing) and data availability (e.g., growth of satellite-derived products) are enabling, for the first time, the development of global scale flood risk models for application in areas where local models are less well developed or prohibitively expensive, or for applications where a synoptic global coverage is important. Despite the increasing granularity of these global models and datasets however, they often still lack the resolution and accuracy to be “locally relevant”, especially where inundation and impact assessments are considered. While a solution to this problem is to downscale global models and datasets to the local scale, setting up local models is hampered by inconsistency between underlying datasets, and the required manual effort to generate downscaled integrated risk models inhibits their global application. To address these issues, we are developing a generalized risk assessment framework, called GHIRAF (Globally-applicable High-resolution Integrated Risk Assessment Framework), which couples data and models to quickly provide locally-actionable information on impact of historic, current- and future world-wide extreme weather events (e.g., storms, extreme rainfall, drought). The framework is designed to support world-wide efforts to reduce and mitigate risks associated with extreme weather events by aiding prevention (scenario-testing, design) and preparation (Early Warning) for extreme events, as well as support response (targeted relief efforts) and recovery (build-back-better) efforts. In this work we discuss application of the framework to study hurricane impacts on the eastern coast of the USA, as well as in data-poor, small island state environments.
Chemical reactivity of thermal treated naturally occurring amphibole asbestos
Authors: Ballirano Paolo , Pacella Alessandro , Tomatis Maura , Turci Francesco , Viti Cecilia , Bloise Andrea
Published: March 2020

Non-occupational (environmental) exposure to naturally occurring asbestos (NOA) represents a potentially important source of risk for human health in several parts of the world. Chemical reactivity of fibres surface is one of the most relevant physical-chemical property to asbestos toxicity and is commonly associated to the presence of Fe at the surface, and in particular to its coordination and oxidation state. However, no detailed information is still available about dependence of chemical reactivity on surface iron topochemistry, which is the basis for defining structure-activity relationships. In this work the chemical reactivity of two amphibole asbestos samples, UICC crocidolite from Koegas Mine, Northern Cape (South Africa) and fibrous tremolite from Montgomery County, Maryland (USA), was investigated after sample heating up to 1200 °C. Ex-situ X-ray powder diffraction (XRPS and the Rietveld method), scanning (SEM) and transmission (TEM) electron microscopy were used for characterizing the mineral fibres before and after the thermal treatment. In addition, thermal stability of the of the amphibole asbestos was analysed in-situ by TG/DSC. Two conventional target molecules (H2O2 and HCOO-) and the DMPO spin-trapping/EPR technique were used to measure the radical activity of both pristine and thermal treated samples. Results show that, after thermal treatment, both amphibole asbestos are completely converted into hematite, cristobalite and pyroxene, still preserving the original fibrous morphology (pseudomorphosis). Notably, in spite of the thermal decomposition, the heated samples show a radical production comparable to that of the pristine ones.
Recognising tectonic and climatic signals in the Paleogene stratigraphy offshore Norway
Authors: Sømme Tor O. , Skogseid Jakob , Embry Patricia , Løseth Helge
Published: March 2020

Landscapes and their sediment routing systems can be exposed to various tectonic and climatic perturbations that affect sediment production, transport and delivery to nearby sedimentary basins. Here we investigate a Paleogene depositional system offshore western Norway that was subjected to long-term (~10 Myr) tectonic perturbation and significant hinterland erosion. Superimposed on this long-term uplift, the system was also subjected to a short-lived climatic perturbation during the Paleocene-Eocene Thermal Maximum (PETM), which lasted ~200 kyr. Regional 3D seismic reflection data is integrated with high resolution well data to map the stratigraphic response to these different scales of perturbations on the depositional system. The initiation of the tectonic perturbation is marked by an angular unconformity in seismic data. A rapid increase in sediment flux followed, causing initial progradation of a shelf-slope wedge. Sediment supply estimates indicate that the tectonic uplift caused an order of magnitude increase in sediment flux to the basin, which peaked in the latest Paleocene. This period coincided with the PETM, which is documented by biostratigraphic data as a discrete event within the overall regressive system. Although the PETM often is characterised by increased continental runoff, no increase in sediment supply is evident from seismic data. This work shows that the system response to tectonic and climatic perturbations may vary along strike, depending on the size of the routing systems and the antecedent topography prior to hinterland uplift. A low supply system may produce a tectonically-linked shelf-slope wedge that is of similar thickness as a climatically-linked wedge in a high supply system. This study documents how the same routing system responded to perturbations operating at different spatial and temporal scales and may help recognise similar process-response relationships in other areas.
Soil erosion controlled by biota along a climate gradient in Chile
Authors: Riveras Nicolás , Witzgall Kristina , Rodríguez Victoria , Kühn Peter , Mueller Carsten W. , Oses Rómulo , Seguel Oscar , Seitz Steffen , Tapia Yasna , Salazar Osvaldo , Wagner Dirk , Scholten Thomas
Published: March 2020

Soil erosion is one of the main problems in soil degradation nowadays and is widely distributed in many landscapes worldwide. Particularly water erosion is widespread and determined by rain erosivity, soil erodibility, topographic factors and the management carried out to mitigate this phenomenon. Although this process is mostly known as a consequence of human management such as agriculture or forestry, it is a process that also occurs naturally, being one of the factors that regulate the shape of the landscape.

One of the main agents that stabilize the soil surface is biota and its activity, either in the form of plants, microorganisms or as an assemblage in the form of a biological soil crust (biocrusts). However, there are limited studies about how and what extent biota drives soil-stabilizing processes. With particular view on the impact of biocrusts on soil erosion, most studies have been carried out in arid and semi-arid regions, so its influence under other climates is largely unknown.

This study focuses on the influence of biota on soil erosion in a temperature and rainfall gradient, covering four climate zones (arid, semi-arid, mediterranean and humid) with very limited human intervention. Other variables such as the origin of the geological formation, geographical longitude and glacial influence were kept constant for all study sites. The effect of vegetation (biocrusts) and its abundance, microbiology and terrain parameters are investigated using rainfall simulation experiments under controlled conditions and by a physico-chemical evaluation of the soil, surface runoff, percolation and sediment discharge, in order to determine the different environmental filtering effects that the soil develops under different climatic conditions.

It is expected that as vegetation vigor and cover increase, soil erodibility will decrease. The biocrust is the protagonist of this stabilization in conditions of low pedological development and will become secondary as edaphoclimatic conditions favor the colonization of plants.

The results of this study will help to achieve a better understanding of the role of biota in soil erosion control and will clarify its influence on soil losses under different climate and slope conditions. Analyses are currently ongoing and first results of our work will be presented at the EGU 2020.
An ocean view of African climate change during the last 620,000 years
Authors: Kaboth-Bahr Stefanie , Asrat Asfawossen , Cohen Andrew S. , Düsing Walter , Foerster-Indenhuck Verena , Lamb Henry , Maslin Mark A. , Schäbitz Frank , Trauth Martin H.
Published: March 2020

It has been a long-standing and passionately discussed hypothesis that important developments in human origins over the last 6-8 Ma coincided with environmental change, including cooling, drying, and wider climate fluctuations. However, testing these hypotheses is difficult as both high resolution climate records and fossil records of early human populations are often incomplete and poorly dated. Thus, to better understand the role that past African climate changes might have played in the evolution and dispersal of our ancestors, in particular Homo sapiens, we have developed a ~620,000 year record of humidity variability from the Chew Bahir basin situated in southern Ethiopia. This 293 m composite lacustrine sediment succession was compiled from two parallel cores HSPDP-CHB14-2A and 2B collected as part of the Hominin Sites and Paleolakes Drilling Project (HSPDP) in 2014. We utilized the log(K/Zr) ratio determined by micro X-ray fluorescence (μXRF) scanning to analyse past moisture changes in the Chew Bahir basin. By placing our results into the existing framework of marine and terrestrial proxy records from various parts of Africa and its surrounding oceans we document a close coupling between the spatio-temporal distribution of African rainfall and sea-surface temperature changes in the Indo-Pacific realm on orbital time scales. We argue that this coupling is facilitated by shifts in the Walker and Hadley circulations in response to insolation variability at the same time.
A global circulation model for the asteroid impact simulations
Authors: Sert Hakan , Temel Orkun , Senel Cem Berk , Karatekin Ozgur
Published: March 2020

In this study, we present a three-dimensional global circulation model (GCM) to investigate the environmental effects of an asteroid impact on the global Earth system. The model is applied to model the atmospheric response of the Cretaceous–Paleogene (K–Pg) extinction event which took place 66 million years ago and resulted in the mass extinction of various animal and plant species. The atmospheric model is developed based on the planetWRF model. First, the paleoclimate model is validated using the proxy data. Then, the sensitivity to atmospheric co2 concentration is investigated. The radiation parameterization scheme of the planetWRF model is modified to include the effect of various climate-active aerosols and gases released after the impact event. The model is also coupled both to a simple one-dimensional ocean mixed layer and a three-dimensional ocean circulation model. Both the atmospheric and oceanic response is investigated.
On vortices initiated over West Africa and their impact on North Atlantic tropical cyclones
Authors: Duvel Jean Philippe
Published: March 2020

Numerous low and mid-level vortices are initiated respectively north and south of 15°N in West Africa and enter the North Atlantic where they may trigger cyclogenesis. Applying an objective vortex tracking algorithm on 38 years of meteorological re-analysis, this work investigates the vortex origin and their role in cyclogenesis with an emphasis on: (i) orography, (ii) seasonal variations and, (iii) merge between low and mid-level vortex tracks. North path vortices are mostly initiated downstream of Hoggar Mountains (5°E, 24°N) and south path vortices are mostly initiated downstream of Fouta Djallon Mountains (15°W, 10°N). About 55% of cyclogeneses in the Main Development Region (MDR: east of 60°W; 5 to 20°N) is associated with vortices initiated on the continent east of 10°W. MDR cyclonic activity is governed by seasonal and interannual variations of the local Genesis Potential Index (maximal in August-September) and not by the number of vortices entering the Ocean. North path vortices, which are more numerous in July, are thus less cyclogenetic compared to south path vortices that are more numerous in August-September. Considering together vortices initiated on the continent and near the coast, about 20% of the cyclogeneses are associated with merge of north and south path vortices and about 14% with north path vortices only. The remaining part is mostly associated with south path vortices. In addition, south path vortices with greater intensity and vertical development between Greenwich and the coast are more cyclogenetic.
The role of parameter estimation strategies on ensemble streamflow prediction results across extratropical Andean catchments
Authors: Muñoz-Castro Eduardo , Mendoza Pablo A. , Vargas Ximena
Published: March 2020

In catchments with a highly variable flow regime, an accurate and reliable hydrological forecasting framework is critical to support water resources management. However, due to model structural deficiencies and changing climatic conditions, the parameter estimates during the calibration period are expected to vary with hydrological conditions. This work aims to test the added value of incorporating potential non-stationarities in hydrologic model parameters on seasonal streamflow forecasts in high-mountain environments, using the ensemble streamflow prediction (ESP) methodology. To this end, we apply the GR4J rainfall-runoff model coupled with the snow accumulation and ablation CemaNeige module in six basins located in Central Chile (30-36° S). We explore the effects of four parameter selection strategies on the quality of seasonal streamflow forecasts produced with the ESP method: (i) a single set of parameters for the entire hindcast period (our benchmark), (ii) using parameters calibrated with a ‘leave-one-year-out’ approach, (iii) using parameter sets based on expected hydroclimatic conditions, and (iv) dual data assimilation to improve the initial condition and parameters before the forecast initialization. Results show that parameters related to production store capacity in GR4J model, and degree-day melt coefficient and weighting coefficient for snow pack thermal state in the CemaNeige module have a high inter-annual variability, with variations of 50% with respect to the benchmark scenario.
The fog/low stratus clouds in the Arctic: detection with multispectral satellite imagery
Authors: Tatsii Daria , Fedoseeva Natalia
Published: March 2020

            The safe operation of aviation and shipping, particularly in areas of insufficient coverage of automatic meteorological stations in the Arctic requires accurate interpretation of satellite images. Operational detection of fog and low stratus clouds and recognizing of them on the background of snow and ice cover and cloudiness of the upper layer is very important challenge. 

           The verified images obtained by Aqua and Terra satellites with a scanning radiometer MODIS, which operates in 36 spectral bands, with wavelengths from 0.4 µm to 14.4 µm, were collected.  With the Beam VISAT 5.0 software, which was designed to work with satellite data in raster format, thematic digital techniques of satellite multispectral information, based on difference in the values of the integral brightness of the images, both in optical and far-infrared ranges of the spectrum, have been developed.  These techniques, models of additive color synthesis, improve the quality of interpretation of fogs and low stratus clouds in terms of the complex structure of cloudiness and underlying surface in polar regions. Developed RGB combinations, which are based on the selected MODIS bands are:

RGB (1.6 µm; 0.8 µm; 0.6 µm)

RGB (0.8 µm; 3.9-8.7 µm; 10.8 µm)

RGB (0.8 µm; 1.6 µm; 3.9-8.7 µm)

RGB ((0-12)-(0-11) µm, (0-11)-(0-3.8) µm, (0-11) µm)

          Analysis of the obtained images has shown that the developed models of color synthesis help to distinguish the fog/low stratus clouds under different conditions of cloudiness and underlying surface accurately.

Key words: remote sensing, satellite imagery, additive color synthesis, fog, low stratus clouds, polar regions
Opportunistic weather sensors: an Amsterdam case study of private weather stations, commercial microwave links and smartphones
Authors: de Vos Lotte , Droste Arjan , Zander Marjanne , Overeem Aart , Leijnse Hidde , Heusinkveld Bert , Steeneveld Gert-Jan , Uijlenhoet Remko
Published: March 2020

Several opportunistic sensors (private weather stations, commercial microwave links and smartphones) are employed to obtain weather information and successfully monitor urban weather events. The ongoing urbanisation and climate change urges further understanding and monitoring of weather in cities. Two case studies during a 17-day period over the Amsterdam metropolitan area, the Netherlands, are used to illustrate the potential and limitations of hydrometeorological monitoring using non-traditional and opportunistic sensors. We employ three types of opportunistic sensing networks to monitor six important environmental variables: (1) air temperature estimates from smartphone batteries and personal weather stations; (2) rainfall from commercial microwave links and personal weather stations; (3) solar radiation from smartphones; (4) wind speed from personal weather stations; (5) air pressure from smartphones and personal weather stations; (6) humidity from personal weather stations. These observations are compared to dedicated, traditional observations where possible, although such networks are typically sparse in urban areas. First we show that the passage of a front can be successfully monitored using data from several types of non-traditional sensors in a complementary fashion. Also we demonstrate the added value of opportunistic measurements in quantifying the Urban Heat Island (UHI) effect during a hot episode. The UHI can be clearly determined from personal weather stations, though UHI values tend to be high compared to records from a traditional network. Overall, this study illustrates the enormous potential for hydrometeorological monitoring in urban areas using non-traditional and opportunistic sensing networks.
GeoLatinas: Fostering an inclusive community to embrace, empower and inspire Latinas in Earth and Planetary Sciences
Authors: Zuluaga Luisa F. , Crisóstomo-Figueroa Adriana , Gomez-Correa Alejandra , Caballero-Gil Rocío P. , Rodriguez Clara
Published: March 2020

Earth and Planetary Sciences are characterized by a lack of gender and ethnic diversity across job sectors, particularly in academia and industry. This imbalance is not representative of current demographic distributions, neither of the general population at large nor the people completing tertiary education in these fields. Gender and ethnic diversity is correlated with improved performance and productivity: In academia as better indicators of research quality and successful grant applications; in industry as higher long-term profitability and better public perception of their corporate values. Despite this, the change has been slow in persuading institutions and companies to create systemic changes to harness this potential. 

Obstacles for inclusion are further amplified for Latinas who, after completing their degrees, navigate professional environments lacking representation and retention, prone to less promotion and access to opportunities. To address these issues, GeoLatinas was created with the mission to embrace, empower, and inspire Latinas worldwide to pursue and thrive in Earth and Planetary Science careers. 

GeoLatinas is a member-driven, circular organization, composed of six key and interactive groups: the (i) GeoLatinas Leadership Council (GLC) formed of active leaders and volunteers, further subdivided into six committees working on particular initiatives; (ii) GeoLatinas Ambassadors (GAs), representing regions, identifying local issues and needs, and leading local events and initiatives; (iii) GeoLatinas Local Teams (GLTs), adapting the GeoLatinas mission and objectives to universities and workplaces; (iv) Liaisons, acting as supporters and collaborators representing other societies from our geo-community; (v) Advisory Committee, formed of experienced women and men in academia and industry; and (vi) Board of Directors, also representing academia and industry.

Facilitated by social media and real-time communication technology, GeoLatinas has become an important networking platform not only for Latinas, but for other demographics for which our mission and objectives resonate. One year after its creation, GeoLatinas has 145 members in 24 countries (72% in academia and 17% in industry). In this presentation, we will share some of our experiences, describing how our initiatives have increased visibility of the talent and potential of Latinas in Earth and Planetary sciences, consequently increasing their access to opportunities, jobs and awards. Furthermore, we will show our impact in encouraging younger generations to identify different career paths, scholarships, research opportunities or jobs. Lastly, we will present key challenges and lessons learned, along with plans to improve long term diversity, inclusion, and retention across sectors in Earth and Planetary disciplines.
Geomechanical modelling of spent fluid reinjection in the Hengill geothermal field
Authors: Ritz Vanille A. , Rinaldi Antonio P. , Colas Elisa , Castilla Raymi , Meier Peter M. , Wiemer Stefan
Published: March 2020

Monitoring micro-seismicity during operations of a geothermal field is critical to the understanding of seismic hazard and changes in the reservoir. In the context of a geothermal project, induced earthquakes are an important tool to enhance the permeability and thus productivity of reservoirs and to image structure and processes. However, felt and/or damaging earthquakes are a major threat to societal acceptance and regulatory license to operate. With the adaptive data-driven tool ATLS (Adaptive Traffic Light System), we aim at managing and mitigating the risk posed by induced earthquakes during stimulation and operations, while at the same time ensuring and optimising the productivity.

The demonstration site for the application of ATLS lies in the Hengill volcanic region located in the South-West of Iceland, host to two power plants (Hellisheiði and Nesjavellir) with a total production capacity of 423 MWe and 433MWth. The production of energy and heat is accompanied by reinjection of the spent geothermal water in dedicated areas, both to maintain production and to comply with legal requirements. These reinjection areas have been showing different seismic responses to drilling and injection operations. We investigate these different behaviours by performing numerical modelling for two of the reinjection regions.

Two models are compared: TOUGH2-Seed, a full 3-dimensional stochastic simulator and an analytical model based on a cumulative density function linking maximum pressure in the reservoir and reactivation. Those two models fulfil two different aspects of the development of an ATLS, with the full 3D allowing an in-depth dive in the driving mechanisms of induced seismicity; and the analytical solution providing a robust and fast approximation of the forecast for real-time application. We show that both models can reproduce observed seismicity patterns in the Hengill geothermal field.
A decade of Oklahoma earthquakes: past, present and future
Authors: Chen Xiaowei , Zhai Guang , Shirzaei Manoochehr , Qin Yan
Published: March 2020

In the last decade, Oklahoma has experienced significant changes in earthquake activities: earthquake rate dramatically increased since 2009, with a peak rate exceeding California, which has gradually decreased in recent years. This “accidental” large scale earthquake experiment provides us with rich datasets to further understand earthquake physics. Here, focusing on analyses of seismicity and accounting for the physics of earthquake nucleation, we link several studies to give a brief overview of Oklahoma earthquakes, and their implications for future studies in induced seismicity.  First, the analysis of spatiotemporal patterns of seismicity rate can help us infer the subsurface hydraulic parameters at both regional and local scales. At the regional level, the hydraulic diffusivities differ between Eastern and Western Oklahoma, separated by the Nemaha Fault, reflecting hydraulic properties of the Arbuckle Group (injection layer). At local scales within individual faults, the analysis suggested similar hydraulic diffusivities to crustal earthquake bursts from other tectonic regions, implying common properties of the crystalline basement.  Second, coupled poroelastic responses to injection on individual faults are essential, and produce seismicity rate forecast that more closely resemble observations. However, local stress tensor variations can significantly influence fault “criticality” and should be taken into account for modeling stress interactions. Third, in addition to injection-related stress changes, earthquake interactions and aseismic slip need to be considered in induced earthquake sequences, and detailed source modeling and statistical analysis are required to understand their roles in the evolutions of individual sequences further. Finally, Oklahoma seismicity offers opportunities to test short- to intermediate-term forecasting based on different physical models, and new windows into earthquake rupture initiations.
The Lorenz convection model's random attractor (LORA) and its robust topology
Authors: Ghil Michael , Charó Gisela D. , Sciamarella Denisse , Chekroun Mickael D.
Published: March 2020

Chekroun et al. (Physica D, 240, 2011) studied the global random attractor associated with the Lorenz (1963) model driven by multiplicative noise; they dubbed this time-evolving attractor LORA for short. The present talk examines the topological structure of the snapshots that approximate LORA’s evolution in time. 

Sciamarella & Mindlin (Phys. Rev. Lett., 82, 1999; Phys. Rev. E, 64, 2001) introduced the methodology of Branched Manifold Analysis through Homologies (BraMAH) to the study of chaotic flows. Here, the BraMAH methodology is extended for the first time, to the best of our knowledge, from deterministically chaotic flows to nonlinear noise-driven systems. 

The BraMAH algorithm starts from a cloud of points given by a large number of orbits and it builds a rough skeleton of the underlying branched manifold on which the points lie. This construction is achieved by local approximations of the manifold that use Euclidean closed sets; the nature of these sets depends on their topological dimension, e.g., segments or disks.  The skeleton is mathematically expressed as a complex of cells, whose algebraic topology is analyzed by computing its homology groups. 

The analysis is performed for a fixed realization of the driving noise at different time instants. We show that the topology of LORA changes in time and that it is quite distinct from the time-independent one of the classical Lorenz (1963) convection model, for the same values of the parameters. Topological tipping points are also studied by varying the parameter values from the classical ones.