bluuebunny/crossref_metadata_2025 huggingface dataset:
A Pyrenean-like model for the Variscan belt in NW Africa : insights from thermometry-based Raman spectroscopy study in the Khenifra Basin
Authors: Leprêtre Rémi , Schito Andrea , Ouchaou Rachid , El Houicha Mohamed , Chopin Francis
Published: March 2020

The Variscan belt in NW Africa is an intracontinental belt, resulting from far-field compressional stress during the closure of the Rheic Ocean between the Late Carboniferous and the Early Permian. In the classical view, this orogen building was preceded by a pre-orogenic stage, namely the Eo-variscan stage, suggested to have occurred at the Late Devonian-Early Carboniferous transition.

This view is now questioned, for multiple reasons. A first structural reason aims at re-interpreting the so-called Eovariscan features as extensional ones. Indeed, although many structures have been described, their integration into a compressional setting is not straightforward. A second reason is geodynamical, since this peculiar stage is bracketed between two general extensional phases recorded at the scale of NW Africa, and this leaves a very short time interval to proceed to a compressional phase that is geodynamically not integrated until today. At last, a third reason stems from early findings from metamorphic works in the Western Meseta that demonstrated the occurrences of previously unnoticed high geothermal gradients inside numerous Early Carboniferous basins (Chopin et al., 2014 ; Wernert et al., 2016 ; Delchini et al., 2018 ; Lahfid et al., 2019).

In this work, we sampled the Khenifra Basin within the easternmost part of the Western Meseta, where the Eovariscan deformation was defined (Allary et al., 1972). We carried on structural observations into the basement and sampled both the Ordovician basement and the Middle(?)-Late Visean series of the basin, which is thought the be extensional. Maximum temperatures reached by the 77 sampled rocks were obtained from the analysis of organic matter with the use of the Raman spectroscopy. The examination of this new dataset demonstrates that the Ordovician series acquired temperatures through a single event, consistently with their common record of the Eovariscan deformation. Instead, the unconformable Visean series on top of the basement show a pronounced basinal asymmetry, from low temperatures (< 160°C) to temperatures equivalent to the Ordovician ones (> 250°C). The Visean series do not record the Eovariscan deformation, and their thermal structure was acquired before the Variscan event, regarding their repartition within the basin. The examination of the different hypotheses for the timing of the maximal temperature acquisition (Variscan, compressional Eovariscan and extensional Eovariscan) leads to a single option only compatible with an extensional Eovariscan context.

The renewal on the knowledge about the early stages of the Variscan orogeny in NW Africa allows us to consider a Pyrenean-like model for the formation of this intraplate belt, resulting from the inversion of hot Early Carboniferous rifted basins.
Example of the interplay of Tectonics, Eustasy and Surface Processes on the North Slope of Alaska Since the Jurassic
Authors: Clinton-Gray Cian , Zahirovic Sabin , Mallard Claire , Salles Tristan , Garrad Daniela
Published: March 2020

The North Slope of Alaska has experienced a complex tectonic and geodynamic history. Although regional paleogeographic reconstructions for the North Slope of Alaska have been interpreted from the geological record, a process-based understanding of the source-to-sink system accounting for both the landscape and sedimentary basin evolution of the region has not been undertaken. Additionally, the interaction of the complex tectonic and climatic forces and their influence on the development of sedimentary basins is not well understood. 

We investigate the influence of tectonics (including deep mantle flow), eustasy and isostasy (including flexure) on the source to sink system on the North Slope to better understand its evolution since the Jurassic.

We use a quantitative forward modelling approach with the open-source surface evolution code Badlands () which incorporate time-dependent dynamic topography estimates from mantle convection models linking plate motions and mantle flow. We present a new method to implement 3D tectonic displacements (including dynamic topography) in landscape evolution models.  

The models capture the North Slope’s complex tectonic history and reproduce the sediment depositional trends as observed from the sedimentological record. The spatial variation in dynamic topography through time results in tilting of the basin which influenced sediment routing directions. Sea-level fluctuations significantly slow the depositional system, trapping more sediment in the proximal basin. Cross-sections of the modelled deposition are used to more closely analyse the shelf margin evolution. They reveal that the models reproduce the large-scale stratal geometries observed from the seismic record, as well as the shelf margin trajectory shifts since the Jurassic. This study demonstrates the importance of linking deep Earth processes to landscape evolution models to gain a better understanding of the long-term evolution of sedimentary basins.
The growth process of river dunes
Authors: Naqshband Suleyman , Hoitink Ton
Published: March 2020

Dunes dominate the bed of sandy rivers and they are of central importance in predicting sediment transport and flow resistance. Using a novel acoustic instrument over migrating dunes in a laboratory setting, we quantify a number of dynamical properties that are crucial in our understanding and modeling of dune response to changes in flow and sediment transport. Measured sediment transport distribution during the initial stage of dune growth reveals a negative spatial lag between dune crest and maximum sediment transport rate. In absence of this spatial lag, the dune field is observed to grow by merging of smaller, faster migrating dunes.
Predictive groundwater flood hazard mapping in lowland karst
Authors: Naughton Owen , McCormack Ted , Campanya Joan
Published: March 2020

The management of karst geohazards requires new and novel strategies to address the complexities inherent in karst systems and the challenges posed by a changing climate. The often rapid and widespread interaction between surface and subsurface hydrology can leave karst terrains uniquely susceptible to flooding from groundwater sources. Quantifying the frequency and magnitude of such flooding is a key step in the management of flood risk. Here, we present a novel interdisciplinary approach developed for predictive groundwater flood hazard mapping in the lowland karst plains of Ireland. This approach ties together direct and earth observation-derived hydrograph data, hydrological modelling, stochastic weather generation and extreme value analysis to generate predictive groundwater flood maps for qualifying sites.

The first step in the approach was the collection of hydrological data for sites susceptible to groundwater flooding. A monitoring network of 50 sites was established in late 2016 to provide baseline data over a 30-month period. Additionally, a methodology for delineating historic flood extents and water elevations from multi-temporal Copernicus Sentinel-1 Synthetic Aperture Radar (SAR) imagery was developed. This allowed hydrograph generation for ungauged sites, whilst also allowing observations of the 2015/2016 extreme flood event at gauged sites which predated monitoring. Next, site-specific hydrological models capable of constructing flood hydrographs from antecedent rainfall and soil moisture conditions were calibrated for 393 sites using a combination of observed and SAR hydrographic data (mean NSE: 0.81). A stochastic weather generator calibrated on 70-year meteorological records was used to generate long-term synthetic rainfall data for each site. These stochastic series, together with long-term average evapotranspiration, were used as input to the site models to produce long-term hydrological series from which annual maxima series were derived. Thereafter, flood frequency analysis was used to estimate predictive flood levels and generate predictive flood maps. This novel applied approach has significantly improved our fundamental scientific understanding of groundwater flooding as a geohazard, whilst also informing regional planning and development to limiting future flood vulnerability.
Daedalus: a Candidate ESA Earth Explorer Mission for the Exploration of the Lower Thermosphere-Ionosphere
Authors: Sarris Theodoros ,   The Daedalus Science Study Team
Published: March 2020

The Daedalus mission has been proposed to the European Space Agency (ESA) in response to the call for ideas for the Earth Observation programme’s Earth Explorers. It was selected in 2018 as one of three candidates for Earth Explorer 10, and is currently undergoing a Phase-0 Science and Requirements Consolidation Study. The goal of the mission is to quantify the key electrodynamic processes that determine the structure and composition of the Lower Thermosphere-Ionosphere (LTI), focusing in particular on processes related to ion-neutral coupling. Daedalus will perform in-situ measurements of plasma density and temperature, ion drift, neutral density and wind, ion and neutral composition, electric and magnetic fields and precipitating particles. An innovative preliminary mission design allows Daedalus to perform these measurements down to altitudes of 140 km and below. These measurements will quantify the amount of energy locally deposited in the upper atmosphere via Joule heating and energetic particle precipitation, estimates of which currently vary by orders of magnitude between models. At the same time, the instrumentation of Daedalus will enable exploration of the variability and dynamics of the LTI, as well as science questions related to connections between the LTI and the atmosphere below. Daedalus will thus study the most under-explored region of the Earth's environment, the "agnostophere", which is the gateway between Earth’s atmosphere and space. In this presentation an overview of the Daedalus Mission Concept will be given, including the status of the ongoing Phase-0 Study.
Hydro-physical properties of temperate hardwood floodplain forest soils in a dry summer season
Authors: Vásconez Navas Lizeth Karina , Gröngröft Alexander , Becker Joscha N. , Eschenbach Annette
Published: March 2020

Understanding the influence of habitat properties on the dynamics of terrestrial ecosystems is a fundamental part of ecosystem research under climate change, especially in areas of high environmental heterogeneity, such as floodplains. The present research is part of the collaborative and interdisciplinary MediAN project (Mechanisms of ecosystem services in hardwood floodplain forests: Scientific analysis and optimization of conservation management), where topics regarding carbon storage of soils and tree biomass, as well as tree vitality and the diversity of herbaceous vegetation are investigated. Thus, in this study we aim to understand and characterize the causes and effects of biotic interactions in relation to the edaphic site properties - in particular between the soil water balance and hardwood forests.

In this context, we identified the spatiotemporal variability of soil hydro-physical properties in six active and former hardwood floodplain forest sites in the Middle Elbe River, Germany. The study sites represent the floodplain geomorphology, therefore varying in elevation (high and low sites), soil texture and hydrological properties, as well as in forest age. We opened three soil profiles per site and installed soil sensors to monitor the variation of volumetric water content (VWC), and water tension at 10 cm, 30 cm, 60 cm, 100 cm and 160 cm depth. Additionally, we installed one groundwater diver and one meteorological station per site. Undisturbed samples were taken per horizon to define the grain size distribution, bulk density and to evaluate soil moisture retention curves.

Preliminary results, from the year 2019 with an unusual dry summer season, show a clear interrelation of soil moisture retention and soil water tension with groundwater level and soil texture. For instance, a predominantly sandy site, located in the high active floodplain, displayed VWC values below 8% throughout the vegetation period and at all depths. Water tension showed higher variation at 10 and 30 cm (2-3.25 pF) compared to deeper soil, which is directly related to precipitation events. These initial observations imply local water stress for the floodplain vegetation; therefore, physiological stress on woody species is expected. In a next step, the dynamics of soil drying will be related to xylem sap flow velocity to estimate effects on the vitality of typical hardwood forest species, such as oaks (Quercus robur L.) and elms (Ulmus laevis) at the representative study sites.
The decadal climate variations simulated in a coupled data assimilation system using only surface pressure observations
Authors: Yang Xiaosong , Delworth Thomas , Zeng Fanrong , Cooke William , Zhang Liping , Compo Gilbert
Published: March 2020

Initializing climate models for decadal prediction is a major challenge, in part due to the lack of long-term subsurface ocean observations and the changing nature of observing systems. In order to overcome these limitations, we have developed a novel method for initializing a climate model for decadal prediction. Using GFDL’s next-generation prediction system, we developed a coupled ensemble data assimilation system, which assimilated only surface pressure observations, since the surface pressure measurements have been made since the late 1800s. Physically, by assimilating high-frequency surface pressure observations we constrain the model to experience a sequence of wind and storms, and thus surface fluxes, that is very similar to what is observed. The hypothesis is that by having the ocean component of the coupled model experience a very similar sequence of surface fluxes as observations, the ocean component of the coupled model will gradually reproduce the same variations as the observed system.

We assimilated the observed surface pressure station data used in the latest 20-century reanalysis. A coupled simulation during 1960 to 2016 has been completed. In this talk, we will review how well the observed decadal climate variations (e.g., PDO and AMO) can be reproduced solely from the surface pressure observations.  In addition, we will explore the multi-decadal variations of the Atlantic meridional overturning circulation (AMOC) and its connection with the North Atlantic sea surface temperature. The feasibility of using this method to initialize coupled climate models for realistic decadal predictions will be discussed in the talk.            
Methane emissions from shale gas production sites in Sichuan, China
Authors: Xue Ming , Zhao Yi-wei , Fan Jun-xin , Cao Dong-dong
Published: March 2020

We performed ground-based methane emission measurements (downwind OTM33A method, on site methane measurements) from shale gas production sites in Sichuan province, China (Changning-Weiyuan region, 18 facilities with 81 wells). The mountainous geological location of the sites, and the limited road access has guaranteed only 2 to 3 downwind OTM-33A measurements. A backpack type high-sensitivity methane analyzer was applied to identify methane emissions and map the atmospheric methane distribution inside the gas facilities. The results showed that: the methane level along the fence line of the 16 facilities kept stable at background concentration, with the other 2 enhanced by less than 2 ppm. Inside the 10 facilities putting into production after 2016, pneumatic controllers from the three-phase separator showed no emission since they were running on electricity. Flowback water tanks were the major methane sources with concentration around 354 to 500ppm. Occasionally, the loose venting outlet of the actuator had leakage with methane concentration around 45 ppm. The application of high-sensitivity methane analyzer inside the facility has provided more detailed emission characteristics which could not be found by infrared camera before. This study could provide insights to the emission behavior from components and the distribution patterns of methane inside the shale gas facilities in Sichuan, China. For sites with a non-favored conditions for downwind measurements, other detection methods such as drone-based might be better to implement.
Consistent Modelling of Non-Equilibrium Thermodynamic Processes in the Atmosphere
Authors: Bowen Paul
Published: March 2020

Approximations in the moist thermodynamics of atmospheric/weather models are often inconsistent. Different parts of numerical models may handle the thermodynamics in different ways, or the approximations may disagree with the laws of thermodynamics. In order to address these problems, we may derive all relevant thermodynamic quantities from a defined thermodynamic potential; approximations are then instead made to the potential itself — this guarantees self-consistency. This concept is viable for vapor and liquid water mixtures in a moist atmospheric system using the Gibbs function but on extension to include the ice phase an ambiguity presents itself at the triple-point. In order to resolve this the energy function must be utilised instead; constrained maximisation methods can then be used on the entropy in order to solve the system equilibrium state. Once this is done however, a further extension is necessary for atmospheric systems. In the Earth’s atmosphere many important non-equilibrium processes take place; for example, freezing of super-cooled water, evaporation, and precipitation. To fully capture these processes the equilibrium method must be reformulated to involve finite rates of approach towards equilibrium. This may be done using various principles of non-equilibrium thermodynamics, principally Onsager reciprocal relations. A numerical scheme may then be implemented which models competing finite processes in a moist thermodynamic system.
Deep water circulation patterns in the Atlantic during MISs 12-11
Authors: Link Jasmin M. , Frank Norbert
Published: March 2020

Glacial Termination V is one of the most extreme glacial-interglacial transitions of the past 800 ka [1]. However, the changes in orbital forcing from Marine Isotope Stage (MIS) 12 to 11 are comparatively weak. In addition, MIS 11c is exceptionally distinct compared to other interglacials with for example a longer duration [2] and a higher-than-present sea level [3] despite a relative low incoming insolation. Therefore, the term “MIS 11 paradox” was coined [4]. However, only little is known about the Atlantic overturning circulation during this time interval [e.g. 5,6].

Here, we present Atlantic-wide deep water circulation patterns spanning the glacial maximum of MIS 12, Termination V, and MIS 11. Therefore, sediment cores throughout the Atlantic were analyzed regarding their Nd isotopic composition of authigenic coatings to reconstruct the provenance of the prevailing bottom water masses.

During the glacial maximum of MIS 12, the deep Atlantic Ocean was bathed with a higher amount of southern sourced water compared to the following interglacial. Termination V is represented by a sharp transition in the high-accumulating sites from the North Atlantic with a switch to northern sourced water masses. MIS 11 is characterized through an active deep water formation in the North Atlantic with active overflows from the Nordic Seas, only disrupted by a short deterioration. A strong export of northern sourced water masses to the South Atlantic points to an overall strong overturning circulation.

 

[1] Lang and Wolff 2011, Climate of the Past 7: 361-380.

[2] Candy et al. 2014, Earth-Science Reviews 128: 18-51.

[3] Dutton et al. 2015, Science 349: aaa4019.

[4] Berger and Wefer 2003, Geophysical Monograph 137: 41-60.

[5] Dickson et al. 2009, Nature Geoscience 2: 428-433.

[6] Vázquez Riveiros et al. 2013, EPSL 371-372: 258-268.
Origin of the Caroline mantle plume and its interaction with the Caroline basin
Authors: Zhang Guoliang , Zhang Ji , Wang Shuai
Published: March 2020

The Caroline Rise has played an important role in the tectonic frame of the western Pacific, however, the nature and origin of the Caroline Rise has long been unclear. The boundary between the Pacific plate and the Caroline plate has long been unclear, thus, it unclear which plate is underneath the Caroline Rise. In this study, we confirmed that the Caroline Rise represents an oceanic plateau formed as a large igneous province based on seafloor sampling. In this study, we have age-dated and analyzed the whole-rock major and trace elements and Sr-Nd-Pb-Hf isotopes of the basalt samples from the Caroline Plateau. The basalt samples are classified into two groups, the alkali group and the tholeiite group. The results of age-dating indicate older ages for the tholeiite group than the alkali group. The tholeiite group basalts are apparently older than the Caroline Islands and are close to the basalts of Ontong Java Plateau in trace element compositions. We suggest that the tholeiite group basalts represent the main stage volcanism and the alkali group basalts represent the late stage volcanism of the Caroline Plateau. The alkali group basalts show trace element and isotope compositions similar to those of the Caroline Islands to the east. The tholeiitie group basalts have involved significant amount of depleted asthenosphere components, which suggests interactions of the Caroline plume with the Caroline basin spreading center. The MORB-like depleted geochemical nature of the Caroline tholeiite group basalts indicates formation of the Caroline Plateau under the young and thin Caroline plate lithosphere. Our results of age and geochemistry of the Caroline Plateau/Seamount system could be explained by the activities of the Caroline hotspot. This work was financially supported by the National Natural Science Foundation of China (91858206, 41876040).
SMOS-based estimation and validation of Total Alkalinity in the Mediterranean basin
Authors: Sabia Roberto , Olmedo Estrella , Cossarini Giampiero , Alvera-Azcárate Aida , Gonzalez-Gambau Veronica , Fernández-Prieto Diego
Published: March 2020

ESA SMOS satellite [1] has been providing first-ever Sea Surface Salinity (SSS) measurements from space for over a decade now. Until recently, inherent algorithm limitations or external interferences hampered a reliable provision of satellite SSS data in semi-enclosed basin such as the Mediterranean Sea. This has been however overcome through different strategies in the retrieval scheme and data filtering approach [2, 3]. This recent capability has been in turn used to infer the spatial and temporal distribution of Total Alkalinity (TA - a crucial parameter of the marine carbonate system) in the Mediterranean, exploiting basin-specific direct relationships existing between salinity and TA.

Preliminary results [4] focused on the differences existing in several parameterizations [e.g, 5] relating these two variables, and how they vary over a seasonal to interannual timescale.

Currently, to verify the consistency and accuracy of the derived products, these data are being validated against a proper ensemble of in-situ, climatology and model outputs within the Mediterranean basin. An error propagation exercise is also being planned to assess how uncertainties in the satellite data would translate into the final products accuracy.

The resulting preliminary estimates of Alkalinity in the Mediterranean Sea will be linked to the overall carbonate system in the broader context of Ocean Acidification assessment and marine carbon cycle.

References:

[1] J. Font et al., "SMOS: The Challenging Sea Surface Salinity Measurement From Space," in Proceedings of the IEEE, vol. 98, no. 5, pp. 649-665, May 2010. doi: 10.1109/JPROC.2009.2033096

[2] Olmedo, E., J. Martinez, A. Turiel, J. Ballabrera-Poy, and M. Portabella,  “Debiased non-Bayesian retrieval: A novel approach to SMOS Sea Surface Salinity”. Remote Sensing of Environment 193, 103-126 (2017).

[3] Alvera-Azcárate, A., A. Barth, G. Parard, J.-M. Beckers, Analysis of SMOS sea surface salinity data using DINEOF, In Remote Sensing of Environment, Volume 180, 2016, Pages 137-145, ISSN 0034-4257, https://doi.org/10.1016/j.rse.2016.02.044.

[4] Sabia, R., E. Olmedo, G. Cossarini, A. Turiel, A. Alvera-Azcárate, J. Martinez, D. Fernández-Prieto, Satellite-driven preliminary estimates of Total Alkalinity in the Mediterranean basin, Geophysical Research Abstracts, Vol. 21, EGU2019-17605, EGU General Assembly 2019, Vienna, Austria, April 7-12, 2019.

[5] Cossarini, G., Lazzari, P., and Solidoro, C.: Spatiotemporal variability of alkalinity in the Mediterranean Sea, Biogeosciences, 12, 1647-1658, https://doi.org/10.5194/bg-12-1647-2015, 2015.

 

 
The FIREX-AQ 2019 Dataset Is Public
Authors: Schwarz Joshua ,   FIREX-AQ Science Team
Published: March 2020

Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) was the most comprehensive investigation on the impact of wildfire and biomass smoke on air quality and weather in the continental United States, and took place in the late summer of 2019. FIREX-AQ explored the chemistry and fate of trace gases and aerosols in smoke with four instrumented research aircraft, satellites, ground-based fixed and mobile laboratories, modeling/forecasting, and coordinated airborne and ground-based fuels information gathering. It focused on both northwestern wildfires and the southeastern U.S. agricultural/prescribed burning.

FIREX-AQ was primarily funded by the US public, hence, the quality-assured dataset acquired from all aspects of the mission has become available to the public, including to the international community. FIREX-AQ data is available for use by researchers around the globe to advance understanding of all the impacts of fire on the atmosphere and on humanity.

Both in-situ and remote sensing data sets were acquired with the NASA DC-8 flying laboratory, while the NASA ER-2 supported several satellite emulators, the NOAA Chem-Otter Twin Otter focused on in situ measurements close to fires and in the dark, and the NOAA Met-Otter Twin Otter supported fire radiative power measurements and wind-profiler measurements to assess fire feedbacks on dynamics. NASA and Aerodyne, Inc. mobile labs focused measurements at very young plume age and in areas (for example valley drainage flow) relevant to air quality, and multiple temporary NASA AERONET sun photometer/lidar observations sites and mobile measurement platforms (“DRAGON”) were deployed to assess vertically resolved influences of smoke on light.

Extensive modeling efforts and meteorological forecasting efforts associated with the measurements resulted in reports that are also public. Coordination with the US Department of Agriculture and various academic institutions enabled inclusion of detailed fuels information including fuel type  and density as well as post-fire information in some cases. Coordination on prescribed burns of different fuels and in different regions in the US provide case studies for connecting emissions to fuels.

A detailed overview of the entire effort is available on-line at: https://www.esrl.noaa.gov/csd/projects/firex-aq/
A Strategy for Scaling ERA5 Sea Winds Using Climate Model Data
Authors: Davison Silvio , Barbariol Francesco , Benetazzo Alvise , Cavaleri Luigi , Mercogliano Paola
Published: March 2020

Over the past decade, reanalysis data products have found widespread application in many areas of research and have often been used for the assessment of the past and present climate. They produce reliable atmospheric fields at high temporal resolution, albeit at low-to-mid spatial resolution. On the other hand, climatological analyses, quite often down-scaled to represent conditions also in enclosed basins, lack the historical sequence of stormy events and are often provided at poor temporal resolution.

In this context, we investigated the possibility of using the ERA5 reanalysis 10-m wind (25-km and 1-hour resolution data) to assess the Mediterranean Sea wind climate (past and scenario). We propose a statistical strategy to relate ERA5 wind speeds over the sea to the past and future wind speeds produced by the COSMO-CLM (8-km and 6-hour resolution data) climatological model. In particular, the probability density function of the ERA5 wind speed at each grid point is adjusted to match that of COSMO-CLM. In this way, past ERA5 winds are corrected to account for the COSMO-CLM energy, while ERA5 scaled wind sequence can be projected in the future with COSMO-CLM scenario energy. Comparison with past observations confirms the validity of the adopted method.

In the Venezia2021 project, we have applied this strategy for the assessment of the changing wind and, after WAVEWATCH III model runs, also the wave climate in the Northern Adriatic Sea, especially in front of Venice and the MOSE barriers, under two IPCC (RCP 4.5 and 8.5) scenarios.

In general, this strategy may be applied to produce a scaled wind dataset in enclosed basins and improve past wave modeling applications based on any reanalysis wind data.
Conditional probabilities of transition from arid to humid environment and vice versa in Europe during the period 1766 -2015
Authors: Bešťáková Zuzana , Máca Petr , Kyselý Jan , Singh Ujjwal , Markonis Yannis , Hanel Martin
Published: March 2020

Currently, there are changes in the hydroclimatic system, with most of Europe affected by droughts. Recent reconstructions on historical precipitation and temperature fields can be used for determination of impacts of meteorological, hydrological and agricultural droughts. Those reconstructions are available for European continent in gridded form (Casty et al.,2007). Aridity index, defined as a fraction of potential evapotranspiration and precipitation, can be used for characterization of humid – wet -- and arid – dry -- regions. It represents the ratio between energy availability and water availability. This study deals with conditional probabilities of transitions from arid to humid environment and vice versa. The aridity index was used to determine the transitions annual basis for the European continent for the period 1766 - 2015. The probabilities were calculated for each year, and for 10-year, 20-year and 30-year periods. It is shown that the recent droughts followed the drying of substantial part of Europe starting in 2014 (Hanel et al., 2018). The changes are most pronounced in Northern and Central Europe.

 

references:

Casty C., Raible Ch. C., Stocker T. F., Wanner H., Luterbacher J., 2007: A European pattern climatology 1766-2000. Climate Dynamics 29. 791-805.

Hanel, M., Rakovec, O., Markonis, Y., Máca, P., Samaniego, L., Kyselý, J., Kumar, R., 2018: Revisiting the recent European droughts in a long-term perspective. Scientific Report 8, 9499.

 
Identification of Hotspots for Heatwaves using Big Data
Authors: Kim Sang-Wook , Park Jongchul , Kim Taehyun , Chae Yeora
Published: March 2020

Impact-based forecasts provide information about the risk of a hazard so that it can be prepared and responded appropriately. In order to mitigate and respond to disasters better, it is necessary to identify the most vulnerable areas, called hotspots. This study identifies hotspots for a heatwave, one of the fatal hazards in South Korea, using high-resolute data in four major cities (Seoul, Busan, Daegu, and Gwangju). High-resolution (100m×100m) income data and floating population data based on Long-Term Evolution (LTE) signals are used as a socio-economic factor of hotspots. The daily maximum temperature that downscaled from the short-range forecast system into 1km×1km is used as a meteorological factor. Each grid point is categorized on the relationship between temperature and floating population by the time. The categories are classified into four groups; points where population increases with temperature, points where population decrease with temperature, points that have low variability, and the others. The areas where the population density increases with temperatures are mainly avoidable to heat, such as parks, subway stations, and indoor shopping centers. The population decreased with temperature in universities, tourist sites, and residential areas. The third group, which is areas of low variability with a coefficient of variation of less than 20%, is areas that do not respond properly to heatwaves. Hotspots are defined as low-income old-age residential areas with low population variability. Those identified hotspots can be concerned as areas that need prior public care to disaster mitigation and response.
Soil microbial respiration responses of nitrogen addition: Evidence from a long-time semi-arid grassland soil incubation
Authors: Wang Zhaomin , Liu Zhongmiao , Guo Binhui , Qi Zhengchao , Niu Decao , Fu Hua
Published: March 2020

Nitrogen is essential for the synthesis of key cellular compounds such as proteins and nucleic acids in all organisms, and it is one of the limiting elements in most terrestrial ecosystems. During past decades, terrestrial ecosystems nutrients availability have altered with nitrogen deposition increases rapidly so that under the soil microbial metabolism activities terrestrial ecosystem biogeochemical cycles are strongly affected. Therefore, maintaining the stability of soil carbon pools, especially microbial carbon pools has great importance for studying global carbon cycle and global climate change processes. Depending on whether soil microbial has already adapted to the environment nitrogen concentration, there exists different results, such as promotion, inhibition, and no impact. To date, how nitrogen will affect soil microbial respiration still has controversy. To determine the effects, we performed a 59 weeks incubation with the soil which has already treated with Urea for 9 years. The soil has been treated with four N addition levels in a semi-arid grassland where located in North-west part of China. We measured CO2 effluxion under different treatments within the same temperature. Our results showed that during the first 8 weeks, soil microbial had strong responses about N addition and N9.2 showed greatest influence with soil microbial respiration. With the time passing, in the time of 9-59 weeks, N0 had highest soil microbial respiration rate while N2.3 was the lowest, this illustrated N2.3 had highest N use efficient (NUE), in order to meet soil microbial stoichiometry, microbial growth became strong C-limitation under the N2.3 treatment. What’s more, comparing with other studies which we shared same study area, we also found that the time of nitrogen application also had strong effect on soil microbial respiration. These results highlight the importance of microbial respiration and may also help us to have a better understand about how N deposition controls terrestrial C flows.
Thermodynamics of Hydrogen-mixed gases
Authors: Hassanpouryouzband Aliakbar , Edlmann Katriona , Heinemann Niklas , Wilkinson Mark
Published: March 2020

Increasing atmospheric CO2 concentration will continue to be a risk if we continue to use fossil fuels as our main energy source. Hydrogen is the ideal low carbon fuel/energy vector to replace fossil fuels facilitating the energy transition, without further increasing gas atmospheric CO2 concentrations. Thermodynamic characterisation of hydrogen and hydrogen mixed gases is important to solve the challenging production and storage issues in a hydrogen-based economy. Thermodynamic characterisation is vital to design more efficient and more economic production and storage processes, and must be undertaken as a crucial first step for wide application of hydrogen-based fuels and their storage. Here we applied a highly accurate equation of state, namely, GERG-2008, to predict various thermodynamic properties (e.g. phase behaviour, density, viscosity, compressibility, and heat capacity) of hydrogen when mixed with other gases including: CO2, CH4, N2, and natural gas. Given the important influence of other constituents in the hydrogen gas stream on the thermodynamic properties of hydrogen, such thermodynamic data could be used for efficient design, development, and deployment of innovative hydrogen production, transport, blending and storage techniques. Understanding the thermodynamic characterisation of hydrogen and hydrogen mixed gasses is particularly important for geological hydrogen storage, where the thermodynamic properties of the injected gas in equilibrium with existing fluids in the storage reservoir is required to estimate the storage capacity. The data is provided over wide range of pressure, temperature, and molar combination representing the range of fuel blending, applications and storage conditions for hydrogen.
Age constraints for rare felsic mantle xenoliths from Elie Ness, Scottish Midland Valley
Authors: Badenszki Eszter , Daly J. Stephen , Whitehouse Martin J. , Upton Brian G. J.
Published: March 2020

EN-101, a rare albitite [Pl +Fe-Ti oxide +Ap +Zrn] xenolith from Elie Ness, Scottish Midland Valley, is hosted by a c. 290 Ma old alkali basaltic diatreme [1, 2].  EN-101 is considered to belong to the Scottish “anorthoclasite suite” comprising xenoliths and megacrysts of various compositions which are interpreted as samples from the upper mantle – lower crust where they form (syenitic) vein or dyke-like bodies e.g., [3, 4, 5]. The “anorthoclasite suite” has been found in all Scottish terranes suggesting that the presumed dyke system must be extensive.

Xenoliths of the “anorthoclasite suite” primarily consist of Na-rich and Ca-poor feldspar megacrysts, with generally high Na/K ratios [3] that are typically accompanied by accessory zircon, apatite, biotite, magnetite and Fe-rich pyroxene whereas garnet and corundum with Nb-rich oxides are only occasionally present [3, 4, 5]. Upton et al. [4, 5] argued that the parental melt of the “anorthoclasite suite” formed though small–fraction melting of metasomatized mantle and subsequent melt–solid phase reaction was also involved.  Upton et al. [5] proposed that crystallization of the anorthoclasite suite samples occurred shortly prior to- or contemporaneously with their entrainment. However so far no in-situ dating has been carried out on these samples.

Early attempts to date the anorthoclasite suite using zircon and feldspar megacrysts from Elie Ness suggested at least a two-stage formation mechanism, where zircon megacrysts yielded a U-Pb age of c. 318 Ma, while euhedral feldspar xenocrysts are significantly younger and roughly coeval with the host volcanism yielding a K-Ar whole-rock age of c. 294 Ma [6].  In this study we present the first in situ U-Pb dating of zircon, which yielded a concordia age of 328 ± 2 Ma (MSWD=0.19; n=12) for EN-101. Zircons εHf328 values range from +5.2 to +7.5 consistent with a mildly depleted source refreshed by metasomatism. These results may indicate that the proposed extensive syenitic veining within the Scottish upper mantle not only has a complex source [5], but is possibly the result of repeated episodes of magma intrusion.

References:

Gernon, T.M. et al. 2013 Bulletin of Volcanology. 75:1-20.

Gernon, T.M. et al. 2016 Lithos. 264:70-85.

Aspen, P. et al. 1990 European Journal of Mineralogy 2:503-17.

Upton, B.G.J. et al. 1990 Journal of Petrology.40:935-56.

Upton, B.G.J. et al. 2009 Mineral Mag. 73:943-56.

Macintyre, R.M. et al. 1981 Transactions of the Royal Society of Edinburgh: Earth Sciences. 72:1-7.
Exploring North Atlantic and North Pacific Decadal Climate Prediction Using Self-Organizing Maps
Authors: Gu Qinxue , Gervais Melissa
Published: March 2020

Decadal climate prediction can provide invaluable information for decisions made by government agencies and industry. Modes of internal variability of the ocean play an important role in determining the climate on decadal time scales. This study explores the possibility of using self-organizing maps (SOMs) to identify decadal climate variability with the ultimate goal of improving decadal climate prediction. SOM is applied to 11-year running mean winter Sea Surface Temperature (SST) in the North Pacific and North Atlantic within the Community Earth System Model 1850 pre-industrial simulation to identify patterns of internal variability in SSTs. Transition probability tables are calculated to identify preferred paths through the SOM with time.  Results show both persistence and preferred evolutions of SST depending on the initial SST pattern.  This method also provides a measure of the predictability of these SST patterns, with the North Atlantic being predictable at longer lead times than the North Pacific. In addition, decadal SST predictions using persistence and lagged transition probabilities are conducted.
On uncertainty in geoscience decision making
Authors: Wilson Cristina , Shipley Thomas
Published: March 2020

Uncertainty is a feature of all science, but geoscientists tend to operate under a higher degree of uncertainty at every level of scientific decision making (Bárdossy and Fodor, 2001). Geoscientists work in fundamentally less predictable environments, where direct observation and experimental control are difficult or impossible due to the large time spans of geologic processes. We are cognitive psychologists who collaborate with geoscientists to better understand the influence of uncertainty on geologic decision making, and to identify the ways expert scientists constrain decision making using heuristics (i.e., rules of thumb).

This presentation will review our work on geologic decision making under uncertainty, focusing on how scientists use heuristics when making spatiotemporal data collection decisions. Our research demonstrates that, when the gradient of data value in the environment is uncertain, scientists use heuristics to decide where to go (in space) to collect data. Heuristics are efficient and effective in many circumstances, but can leave experts vulnerable to decision bias. In ongoing research, we explore whether new field workflows (uncertainty mapping) or mobile robotic platforms (terrestrial, aerial) can debias decision making. Our research agenda is translational, with the goal of improving scientists’ interpretation of geologic phenomena in the field.
Seismic Precursors in Central Italy using Autocorrelation Measurements
Authors: Delouche Estelle , Stehly Laurent , Voisin Christophe
Published: March 2020

The aim of this study is to identify precursors related to fluid pressure changes at depth to large earthquakes that occured in central Italy such as the 2009 Mw6.3 L'Aquila and the 2016 Mw6.2 Amatrice earthquake. To that end, we monitor the temporal evolution of the crust using a new method called Coherence of Correlated Waveforms [CCW] that uses seismic noise autocorrelation measurements. This allow us to look for changes in the medium with a high temporal resolution of 5 days. Our measurements of the CCW show that the L'Aquila Earthquake (2009-M6.3) is preceded by a 150-day oscillation whose amplitude and frequency progressively increases until the rupture. The high Vp/Vs ratios measured on the foreshocks of L’Aquila earthquake correspond to the CCW drop periods, suggesting the sensitivity of the measurement to crusty fluids.

Analysing 17 years of data, we found that this signal occurred only before the L'Aquila and the Amatrice earthquakes. This suggests the existence of a unique nucleation process.

Finally, for the 2016 Amatrice Earthquake, using an array of 25 seismic stations we are able to map the geographical extension of this precursory signal. This pattern, evolving over time, suggests diffusion phenomena in the upper crust.

 
Feasibility of Radial Borehole Fracturing in Geothermal Exploitation: an Experimental Study
Authors: Tian Shouceng , Guo Zhaoquan , Sun Yuqi , Wang Qisheng , Liu Qingling , Sheng Mao , Shen Zhonghou
Published: March 2020

Enhanced geothermal system (EGS) is an important way of geothermal development, which takes advantage of the fractures serving as the channels of working fluid flow and heat transfer. But constrained by the geometries of hydraulic fractures formed through conventional fracturing technologies, the heat transfer areas are limited. Radial borehole fracturing combines hydraulic fracturing and radial boreholes which extend to the formation radially from 10 to 100 meters and have diameters of 20 to 50 millimeters. This paper aims to investigate whether radial borehole fracturing can increase the fracture areas in EGS system comparing with perforation fracturing. 
Nine cubic concretes (300*300*300mm) were cast after mixing sand, cement and water. Six of them contained radial boreholes and three had perforations. All cubic concretes were heated to 200℃ and fractured by a tri-axial fracturing test system with injection rates of 30ml/min and horizontal principal stress differences being 6 MPa. Then the fractures were scanned and the fracture areas were calculated. Three different angles between radial boreholes/perforations and maximum horizontal stress (0°, 45°, 90°) and two quantities of radial boreholes (2, 4) were studied. 
Experimental results show that radial borehole fracturing creates greater fracture areas then that of perforation fracturing if the orientations of radial boreholes and perforations do not consist with the direction of maximum horizontal stress. Because the fractures turn to the direction of maximum horizontal stress more quickly for perforation fracturing when perforations and radial boreholes have identical angles, namely radial boreholes guide the fractures better as they extend into the concretes. Besides, concretes with 4 radial boreholes have smoother fractures than concretes with 2 radial boreholes. In addition, the breakdown pressure of radial borehole fracturing is lower and increasing the quantities of radial boreholes reduces the breakdown pressure. 
This experimental investigation reveals that radial borehole fracturing can form larger fracture areas than perforations fracturing, which promotes the efficiency of heat extraction in EGS system.
Revisiting the Strongest Martian X-Ray Halo Observed by XMM-Newton on 2003 November 19–21
Authors: Yan Limei , Gao Jiawei , Chai Lihui , Zhao Lingling , Rong Zhaojin , Wei Yong
Published: March 2020

On 2003 November 20–21, when the most intense geomagnetic storm during solar cycle 23 was observed at Earth, XMM-Newton recorded the strongest Martian X-ray halo hitherto. The strongest Martian X-ray halo has been suggested to be caused by the unusual solar wind, but no direct evidence has been given in previous studies. Here, based on the Mars Global Surveyor (MGS) observations, unambiguous evidence of unusual solar wind impact during that XMM-Newton observation was found: the whole induced magnetosphere of Mars was highly compressed. The comparison between the solar wind dynamic pressure estimated at Mars from MGS observation and that predicted by different solar wind propagation models suggests that the unusal solar wind is probably related to the interplanetary coronal mass ejection observed at Earth on 2003 November 20.