bluuebunny/crossref_metadata_2025 huggingface dataset:
The final closure of the Vardar Ocean: paleomagnetic, AMS and structural results
Authors: Márton Emö , Toljić Marinko , Lesić Vesna , Cvetkov Vesna
Published: March 2020

The Vardar zone divides units of African affinity from units of the European margin. It is characterized by extensional opening of an oceanic domain during the Triassic and Jurassic followed by divergent simultaneous obduction of the oceanic litoshphere over the continental units in the Upper Jurassic. However, a stripe of the oceanic domain persisted till the Cretaceous and Paleogene convergence. The remnants of the last closing part of the Vardar ocean are found in the Sava zone.

In this paper recently published and new paleomagnetic, AMS results in combination with structural observations will be presented from Upper Cretaceous sediments and Oligocene –Lower Miocene igneous rocks representing the areas bordering the Sava zone from the western and eastern sides, respectively and from the upper Cretaceous flysch deposited in the Sava zone.

In the areas W and E of the Sava zone, respectively, the primary remanences of the igneous rocks point to post-Oligocene CW rotation of about 30°. The sediments carry secondary magnetizations, imprinted during magmatic activity. Compared to the areas flanking it, the sediments of the Sava zone were intensively folded during the Upper Cretaceous and Paleogene and the paleomagnetic signals, which exhibit smeared distribution close to the present N, are of post-folding age. The AMS foliation and bedding planes are sub-parallel, thus the deformation must have been weak. Fold axes and AMS lineations are roughly N-S oriented, pointing to the deformational origin of the AMS lineations. These observations form the Sava zone will be discussed in the context of the post-Oligocene CW rotation of the flanking areas and the general NE-SW orientation of the compressional stress field outside of the zone.

Acknowledgement. This work was financially supported by the National Development and Innovation Office of Hungary, project K 128625 and by the Ministry of Education and Science of the Republic of Serbia, project 176015.
Validation of reconstructed hydroclimate variables for past drought assessment
Authors: Hanel Martin , Nasreen Sadaf , Vargas Mijael , Singh Ujjwal , Máca Petr , Rakovec Oldřich , Kumar Rohini , Markonis Yannis
Published: March 2020

In present paper we compare the reconstructed gridded seasonal precipitation (P) and temperature (T) for Europe [1,2] to the available station data from the GHCN [3,4] network going back to 1800. The basic statistical properties at various time-scales ranging from 1/4 to 30 years are examined. It is shown, that there are significant biases in the reconstructed P and T and the bias in mean and variability considerably vary over the time-scales. The same applies for considered drought indices. We further investigate how the simulation of hydrological model driven by reconstructed data compares to that based on station data and runoff from GRDC database. In addition, a set of data-driven methods is used to link the reconstructed and observed P and T data to observed runoff, the results are validated and a reconstruction back to 1500 is provided. Finally, we check to what extent the raw proxy data can be used for drought reconstruction.

[1] https://doi.org/10.1007/s00382-005-0090-8
[2] https://doi.org/10.1126/science.1093877
[3] https://doi.org/10.1175/JCLI-D-18-0094.1
[4] doi:10.7289/V5X34VDR
Towards a global assessment of future glacial lakes and related hazards, risks and opportunities
Authors: Frey Holger , Huggel Christian , Allen Simon , Emmer Adam , Shugar Dan , Farinotti Daniel , Huss Matthias , Machguth Horst
Published: March 2020

The formation of new lakes in areas uncovered by retreating glaciers is a phenomenon that is often accompanying glacier retreat. On the one hand, such glacial lakes constitute a potential source of hazards and risks in the form of glacial lake outburst floods (GLOFs), but also amplify the potential reach of other mass movements when involved in cascading process chains. On the other hand, these new lakes might provide opportunities as well, as they are attractive elements in changing mountain landscapes and provide a significant water storage and hydropower potential. Here, we present an approach to establish the first global assessment of the characteristics, risks and opportunities provided by the formation of new lakes in glacierized mountain regions. This study is currently in the phase of concept development, in our contribution we present the planned methodological steps and some preliminary results.

In our approach, we draw on recently published datasets of ice thickness distributions of all glaciers around the world to detect the sites of potential future lake formation and extract general characteristics, such as lake depth and volume, as well as the elevation distribution. In combination with a new global glacial lake inventory, we estimate the total number of glacial lakes for each of the world’s mountain ranges, and contrast the share of already existing glacial lakes with the share of potential future glacial lakes. In combination with a global glacier evolution model (GloGEM), formation dates of these future lakes are estimated, considering different RCPs.

A major focus will be put on the assessment of regional hazards and risks. By analyzing the topographic potential around all future lakes from digital elevation information and a globally complete glacier inventory (RGI), the susceptibility for mass movement impacts is assessed in a generic way for each lake. Simple flow routing modeling will be used to evaluate the potential downstream impact. In combination with census data and other socio-economic indicators, a preliminary danger or risk assessment can be made in order to identify future hotspots of GLOF risks. In combination with globally available data on glacier runoff contributions to streamflow, regions are identified where more detailed evaluations of the water storage potential provided by such new lakes are of particular relevance.

The results of this work will allow anticipating hotspots of potential future GLOF hazards and risks at a local to global level. Further, important information to decision makers will be provided for long term planning regarding risk and water resources management as well as climate change adaptation measures and taking advantage of the opportunities provided by the formation of new glacial lakes.
Decreasing Antarctic surface mass balance due to runoff-dominated ablation by 2100
Authors: Kittel Christoph , Amory Charles , Agosta Cécile , Jourdain Nicolas , Hofer Stefan , Delhasse Alison , Fettweis Xavier
Published: March 2020

The surface mass balance (SMB) of the Antarctic ice sheet is often considered as a negative contributor to the sea level rise as present snowfall accumulation largely compensates for ablation through wind erosion, sublimation and runoff. The latter is even almost negligible since current Antarctic surface melting is limited to relatively scarce events over generally peripheral areas and refreezes almost entirely into the snowpack. However, melting can significantly affect the stability of ice shelves through hydrofracturing, potentially leading to their disintegration, acceleration of grounded ice and increased sea level rise. Although a large increase in snowfall is expected in a warmer climate, more numerous and stronger melting events could conversely lead to a larger risk of ice shelf collapse. In this study, we provide an estimation of the SMB of the Antarctic ice sheet for the end of the 21st century by forcing the state-of-the-art regional climate model MAR with three different global climate models. We chose the models (from both the Coupled Model Intercomparison Project Phase 5 and 6 - CMIP5 and CMIP6) providing the best metrics for representing the current Antarctic climate. While the increase in snowfall largely compensates snow ablation through runoff in CMIP5-forced projections, CMIP6-forced simulations reveal that runoff cannot be neglected in the future as it accounts for a maximum of 50% of snowfall and becomes the main ablation component over the ice sheet. Furthermore, we identify a tipping point (ie., a warming of 4°C) at which the Antarctic SMB starts to decrease as a result of enhanced runoff particularly over ice shelves. Our results highlight the importance of taking into account meltwater production and runoff and indicate that previous model studies neglecting these processes yield overestimated SMB estimates, ultimately leading to underestimated Antarctic contribution to sea level rise. Finally, melt rates over each ice shelf are higher than those that led to the collapse of the Larsen A and B ice shelves, suggesting a high probability of ice shelf collapses all over peripheral Antarctica by 2100.
The use of hydromulches in organic farming: Effect on different soil parameters in Central Spain
Authors: Moreno Marta M. , Villena Jaime , González-Mora Sara , Atance Concepción , Ramírez Manuel , Campos Juan A. , Moreno Carmen
Published: March 2020

In recent years, the problem arising from the weed control in perennial crops is increasing, both in young woody crops during the first years of cultivation and in established plantations. The control of weeds through herbicides, the most widespread practice, presents many inconveniences, among which we can mention the appearance of weeds resistant or tolerant to them, crop phytotoxicities, especially in young plantations, or the significant reduction in the active materials allowed. Another aspect to take into account is the search for techniques that allow saving crop water consumption by reducing soil evaporation

Therefore, in this work we evaluate the effect of three mixtures based on by-products derived from the agricultural sector, mixed with a binder and recycled paper paste and applied in liquid form on the ground with subsequent solidification (hydromulch), on different soil parameters (soil water content, temperatura and flow of CO2) in a young olive plantation in containers of 700 liters capacity. Additionally, two control treatments were included (manual weeding and a no-weeding treatments).

In summary, and as preliminary results, hydromulches increased the soil water content, reduced slightly the soil temperature in the summer season and increased the flow of CO2, indicative of a higher soil microbial activity, closely related with the air temperature and the soil moisture. These preliminary results position hydromulches as an interesting alternative to herbicides and the conventional plastic mulches.

 

Keywords: hydromulches, soil CO2 flow, soil temperatura, soil water content.

Acknowledgements: Project RTA2015-00047-C05-03 - INIA (Spanish Ministry of Economy and Competitiveness).
Porosity and hydrocarbon composition evolution in shales from the Domanic and Bazhenov Formations: Insights from pyrolysis and aqua thermolysis experiments.
Authors: Gafurova Dina , Kalmykov Anton , Korost Dmitriy , Margarita Tikhonova , Olesia Vidishcheva
Published: March 2020

The Domanic and Bazhenov Formations are the largest unconventional oil and gas resources in Russia. In this regard, research of mechanisms and transformation features of pore space structure, as well as hydrocarbon fluids composition are of greatest interest. In recent time technologies for modeling of thermal maturation of rocks under close to reservoir conditions similar, such as pyrolysis and aqua pyrolysis can be used. The natural process of organic matter maturation has a direct impact on the rock pore space alterations. Experimental studies of rocks (more than 100 experiments) with monitoring of the pore space using computer microtomography were performed. As a result of research, it was possible to clarify the influence of rock characteristics on the transformation of the pore space, as well as on the hydrocarbons composition. The structural features of the mineral part of the rock control the distribution of organic matter: for rocks with a layered distribution of organic matter, the formation of a crack system is characteristic. In samples with a massive structure, newly formed pores were noted. The rocks with the highest organic matter content from 20% were characterized by the formation of lenses (Fig. 1). The content of organic matter and its maturity directly affect the volume of the newly formed pore space.

Performed investigations allowed to reveal the trends of hydrocarbons generation in source rocks and unconventional reservoirs formation. Also heating of rocks by various methods under reservoir conditions approved potential of tertiary methods of reservoir stimulation. Pyrolysis in-situ of Bazhenov and Domanic source rocks would allow to generate “synthetic” oil of similar to natural one composition and increase permeability of rocks by pores and cracks formation.

This work was partially (fully) supported by RFBR grant 18-35-20036.
The unusual floods and flood frequency in 1858–1878 dry period in Central and Western Europe
Authors: Elleder Libor , Kašpárek Ladislav , Krejčí Jakub , Šírová Jolana , Racko Stanislav
Published: March 2020

According to the present knowledge, the second half of the 19th century meant the end of the Little Ice Age and gradual warming.  This is, however, undoubtedly a fairly simplified statement.  Our contribution presents the period of 1858–1878: (1) from the point of view of drought but also (2) regarding frequency of floods. The aggregation for this period of weather-driven risks such as droughts, floods, strong winds and high tides, is worth attention.  The length of the drought period of 1858–1878, the absolute value of rainfall deficits and the length of seasonal droughts, as well as their impacts, are a certain warning in terms of our present.

Surprisingly, in such a dry period we witness an accumulation of important and extreme flood episodes as well. The regional catastrophic floods of 1858, and winter extensive floods of 1862 and 1876, may serve as excellent examples.  Furthermore, the Elbe catchment recorded floods with return periods of 10–20 years in 1860, 1865 and 1872. For this period, an occurrence of intensive mesoscale flash flood events with extreme hydrological parameters, high number of fatalities and large damages are of the utmost importance (e.g. 1868-Switzerland, 1872-Czechlands, 1874- Catalonia, 1875-South France). Our contribution builds on earlier analysed flood events of 1872, 1875 and drought period presented at EGU earlier. The contribution stresses the analogies and differences with present situation in 2014–2019.  We mainly address the situation in Czech lands, Central Europe interpreted in wider European context.
Climate Extremes in the Lake Victoria Basin: The ELVIC CORDEX Flagship Pilot Study
Authors: van Lipzig Nicole , Van de Walle Jonas , Thiery Wim , Nikulin Grigory , Wu Minchao , Glazer Russell , Coppola Erika , Pinto Joaquim , Fink Andreas , Ludwig Patrick , Rowell Dave , Berthou Ségolène , Finney Declan , Marsham John
Published: March 2020

Extreme weather events, like heavy precipitation, heat waves, droughts and wind storms have a detrimental impact on East African societies. The Lake Victoria Basin (LVB) is especially vulnerable, since nightly storms on the lake catch fishermen by surprise. As the frequency and intensity of climate extremes is projected to further increase substantially with climate change, so do the risks, with potentially major consequences for livelihoods and policy in the LVB.

The ultimate aim of the ELVIC CORDEX-FPS is to investigate how extreme weather events evolve in the future in the LVB and to provide improved probabilistic information to the impact community. ELVIC (Climate Extremes in the Lake Victoria Basin) brings together different research groups that perform simulations with multiple high-resolution regional climate models operating at the convection-permitting scale (CPS) (https://ees.kuleuven.be/elvic).

As a first step towards this overall goal, the added value of the CPS on the representation of deep convective systems in Equatorial Africa was assessed. For this purpose, 10-year present-day model simulations were carried out with five regional climate models both at the CPS and at the scale where convection was parameterized, namely COSMO-CLM, RegCM, HCLIM-AROME, WRF and the Met Office Unified Model. From a comparison of model output with different observational products, no robust improvement was found for seasonal average meteorological variables. Moreover, the change in the seasonal precipitation when going to CPS differs between the models. A robust improved performance was found for deep convection, reflected in an improved representation of the daily precipitation cycle. Preliminary results also point towards an improvement in the representation of extreme precipitation. This suggests that regional climate model simulations at the convection-permitting scale are indeed relevant to assess the climate sensitivity of extreme precipitation in the Lake Victoria Basin.
Mitigating for coastal erosion and C loss in the Mississippi Delta; do river water diversion do more harm than good?
Authors: Corstanje Ronald , Spera Alina , White John
Published: March 2020

Sediment, nutrient deprivation and saltwater intrusion, among other factors, are driving widespread organic soil collapse and marsh loss in the Mississippi River Delta. Freshwater wetland diversions were designed to reintroduce Mississippi River water and sediment into the adjacent basins to manage salinity and mitigate land loss. However, there is concern that loading of excess nutrients from the Mississippi River into Barataria Basin wetlands can potentially lead to increased soil OM decomposition, less soil strength or increasing buoyancy and decreased belowground biomass. A baseline study was effected of a 3,145 km2 area of wetlands and estuaries within Barataria Basin in 2007, in which the spatial variation in plant and soils were described at 140 stations before full scale diversion operations began in 2009. A subsequent spatial survey was conducted in 2018 after 11 years of diversion influence. By resampling the top 20 cm, separated into 0-10 cm and 10-20 cm layers, in 2018 provides an assessment of the status of those soils produced since 2007 and provides context for changing soil conditions. For the 2018 sampling, the soil
Ocean carbon storage and release over a glacial cycle
Authors: Rae James , Foreman Alan , Crumpton-Banks Jessica , Burke Andrea , Charles Christopher , Adkins Jess
Published: March 2020

Perhaps the most important feedback to orbital climate change is CO2 storage in the deep ocean.  By regulating atmospheric CO2, ocean carbon storage synchronizes glacial climate in both hemispheres, and drives the full magnitude of glacial-interglacial climate change.  However few data exist that directly track the deep ocean’s carbon chemistry over a glacial cycle.  Here, we present geochemical reconstructions of deep ocean circulation, redox, and carbon chemistry from sediment cores making up a detailed depth profile in the South Atlantic, alongside a record of Southern Ocean surface water CO2, spanning the last glacial cycle.  These data indicate that initial glacial CO2 drawdown is associated with a major increase in surface ocean pH in the Antarctic Zone of the Southern Ocean, cooling at depth, enhanced deep ocean stratification, and carbon storage.  Deep ocean carbon storage and deep stratification are further enhanced when CO2 falls at the onset of Marine Isotope Stage 4, and are also pronounced during the LGM, illustrating a link between orbital scale climate stages and deep ocean carbon.  However our data also illustrate non-linear feedbacks to orbital forcing during glacial terminations, which show abrupt decreases in pH in Southern Ocean surface and subsurface waters, as CO2 is rapidly expelled from the deep ocean at the end of the last ice age.
Organic and inorganic whole system metabolism in two acidified coastal systems in Ireland
Authors: Guerra Maria Teresa , Rocha Carlos
Published: March 2020

Organic and inorganic whole system metabolism for two Irish coastal areas were compared to evaluate carbonate system resilience to acidification. The two systems are characterized by contrasting watershed input types and composition. Kinvara Bay is fed by Submarine Groundwater Discharge (SGD) derived from a karstic catchment while Killary Harbour is fed by river discharge draining a siliciclastic catchment. Freshwater sources to sea have distinct Total Alkalinity (TA) and Dissolved Inorganic Carbon (DIC) concentrations, higher and lower than the open ocean, respectively, but both evidence seasonally variable low pH, ranging from 6.20 to 7.50. Retention of TA and DIC was calculated for the two areas using LOICZ methodology. In Kinvara bay, annually averaged retention of DIC was greater than for TA (5 × 104 and 1.5 × 105 mol d-1), suggesting the system is acidifying further. Conversely, Killary Harbour shows negative TA and DIC retention, with DIC:TA <1, suggesting an internal buffer against ocean acidification is operating.

Net Community Production (NCP) was calculated for both systems using Dissolved Oxygen data. Subsequently, we estimated Net Community Calcification (NCC) from the ratio between TA and DIC. NCP was always positive in Killary Harbour with an average of 318 mmol O2 m-2 d-1 (equivalent to 89 mol C m-2 y-1). However, Kinvara Bay shows relatively lower positive NCP in spring and summer (average of 46 mmol O2 m-2 d-1), but negative NCP in autumn and winter. Therefore, Kinvara Bay’s Total Organic Carbon (TOC) production was low, at ~21 g m-2 y-1 and not enough to overcome acidification driven by the SGD source composition. These results emphasize the complexity of interactions between the drivers of coastal acidification rate, affecting our ability to accurately assess the resilience of the carbonate system in these areas to ocean acidification pressure in the future.
An offline reanalysis of land surface variables with LDAS-Monde forced by a kilometric scale NWP system
Authors: Bonan Bertrand , Albergel Clément , Napoly Adrien , Zheng Yongjun , Calvet Jean-Christophe
Published: March 2020

LDAS-Monde is the offline land data assimilation system (LDAS) developed by Météo-France’s research centre (CNRM) aiming to monitor the evolution of land surface variables (LSVs) at various scales, from regional to global. It combines numerical simulations from the multilayer and interactive vegetation ISBA land surface model and satellite-derived observations of surface soil moisture and leaf area index (LAI). LDAS-Monde has been successfully validated over the globe.

In this work, we study the possibility to set up LDAS-Monde to the context of the kilometric spatial resolution. In this context, we assimilate satellite observations of LAI from the Copernicus Global Land Service (CGLS) into the ISBA land surface model forced with Météo-France’s small scale numerical weather prediction system AROME. We produce a reanalysis of LSVs at 2.5-km spatial resolution over the AROME domain centred on France starting from 2017. The quality of this reanalysis is assessed by comparing the obtained reanalysis with satellite products of LAI and surface soil moisture from e.g. CGLS and in-situ measurements of soil moisture from various networks (SMOSMANIA, …). We also show the ability of our system to monitor the evolution of LSVs in the context of the severe drought that France suffered during the summer 2018. LDAS-Monde at 2.5-km spatial resolution displays a great potential for agricultural monitoring at high resolution. We also plan to adapt our framework to 1.0-km spatial resolution.
Atmospheric observations of the water vapour continuum in the near-infrared windows
Authors: Elsey Jon , Coleman Marc , Gardiner Tom , Menang Kaah , Shine Keith
Published: March 2020

 

The water vapour continuum is an important additional component to the total absorption of atmospheric radiation by water vapour. However, while it has been studied extensively in the far and mid-infrared, there are significant uncertainties in its absorption strength in the near-infrared, since the relatively few laboratory measurements in this region disagree by a factor of ~50. Compounding this uncertainty is the lack of observations in atmospheric conditions; measurements are typically made at room-temperature or above, but the continuum has significant (and uncertain) temperature dependence. We aim to reduce this uncertainty by presenting observations of the near-infrared water vapour continuum from Camborne, UK at sea level using a sun-pointing, radiometrically-calibrated Fourier transform spectrometer in the window regions between 2000–10000 cm−1. When extrapolated to atmospheric temperatures, we show good agreement with various laboratory studies in the 4 µm window.  Our results show that the widely-used MT_CKD continuum is too weak by a factor of ~5 in the in the centre of the 2.1 µm window in line with laboratory analyses, with implications for energy balance studies and remote sensing. Our results at 1.6 µm show significantly stronger absorption than MT_CKD. This may be in part due to the influence of atmospheric aerosol, which forms a rather significant part of the uncertainty in our measurements at higher wavenumbers. We demonstrate the difficulties in making such field observations, and highlight the need for future observations both from the laboratory and the field, with the aim of including the water vapour continuum in the HITRAN spectroscopic database.
Prehistoric sheep/goats husbandry in Xinjiang, China—Evidence from bone stable carbon and nitrogen isotopes
Authors: Dong Weimiao
Published: March 2020

Sheep and goats have been introduced into northwest China as important livestock for some four thousand years. The frequency of sheep/goats’ bones in prehistoric archeological sites in Xinjiang can be a proof of their importance in people’s life. This study focuses on food reconstruction of prehistoric sheep/goats across Xinjiang to illustrate whether there is a difference on sheep/goats husbandry. Bone samples from 11 sites were isotopically analyzed together with 4 sets of published data, 220 pairs of sheep/goats bone stable carbon and nitrogen isotopes in total from 15 sites across Xinjiang with time span of ca, 4000 cal BP to ca. 2000 cal BP were produced. 9 sites each with sample number no less than 10 were further studied. It revealed that generally sheep/goats from 4 oasis sedimentary farming societies have both higher 13C values and higher 15N values, although highly fluctuated. It is highly likely that C4 plants such as foxtail millet or common millet must have not been a stranger around their environment. As for their remarkably high 15N values, drought stress in arid environment may have been one reason, fertilized soil after long time relatively intensive human activity may have also contributed to this. In the meanwhile, sheep/goats from 5 pastoralism or transhumance societies have homogenous and more negative 13C values, most of which are lower than -18‰, meaning that there was barely no C4 plants in their diet. In contrast, 15N values of them are lower than that of farming societies as a whole but more scattered, seasonally different pastures with diversified 15N background could be the reason.
Pb-Pb ages and Pb initial isotopic composition of lunar meteorites: new constrains on the timing of lunar magmatism and its mantle sources
Authors: Merle Renaud , Nemchin Alexander , Whitehouse Martin , Snape Joshua , Kenny Gavin , Bellucci Jeremy , Connelly James , Bizzarro Martin
Published: March 2020

Constraining the duration of magmatic activity on the Moon is essential to understand how the lunar mantle evolved chemically through time. Determining age and initial isotopic compositions of mafic lunar meteorites is a critical step in defining the periods of magmatic activity that occurred during the history of the Moon and to constrain the chemical characteristics of mantle components involved in the sources of the magmas.

We have used the in-situ Pb–Pb SIMS technique to investigate lunar gabbros and basalts, including meteorites from the Northwest Africa (NWA) 773 clan (NWA 2727, NWA 3333, NWA 2977, NWA 773 and NWA 3170), LAP 02224, NWA 4734 and Dhofar 287A. These samples have been selected as they all belong to the dominant chemical group of low-titanium mare basalts and there is no clear agreement on their age. We have obtained ages of 2978 ± 13 Ma for LAP02224, 2981 ± 12 Ma for NWA 4734 and 3208 ± 22 Ma for Dhofar 287. For the NWA 773 clan, four samples (NWA 2727, NWA 773, NWA 2977, NWA 3170) yielded isochron-calculated ages that are identical within uncertainties with an average age of 3086.1 ± 4.8 Ma. The gabbroic sample NWA 3333 yielded an age of 3038 ± 20 Ma suggesting that two distinct magmatic events are recorded in the meteorites of the NWA 773 clan.

The entire age dataset from lunar mafic meteorites was screened to identify data that are problematic from an analytical viewpoint and/or show evidence of resetting and terrestrial contamination. This refined dataset combines the ages of mafic lunar meteorites and Apollo samples and suggests pulses in magmatic activity, with two main phases between 3350 and 3100 Ma and between 3900 and 3550 Ma followed by a minor phase at ~3000 Ma.

The evolution of the Pb initial ratios of the low-Ti mare basalts between 3400 Ma and 3100 Ma suggests that these rocks were progressively contaminated by a KREEP-like component. Nevertheless, the ~3000 Ma mafic rocks (NWA4734 and LAP02224) show significant differences in terms of initial 204Pb/206Pb ratios that illustrates that the lunar mantle is probably more heterogeneous than has previously been assumed.
A Web-Based Virtual Research Environment for Marine Data
Authors: Buurman Merret , Mieruch Sebastian , Barth Alexander , Troupin Charles , Thijsse Peter , Zamani Themis , Krishnan Naranyan
Published: March 2020

Like most areas of research, the marine sciences are undergoing an increased use of observational data from a multitude of sensors. As it is cumbersome to download, combine and process the increasing volume of data on the individual researcher's desktop computer, many areas of research turn to web- and cloud-based platforms. In the scope of the SeaDataCloud project, such a platform is being developed together with the EUDAT consortium.

The SeaDataCloud Virtual Research Environment (VRE) is designed to give researchers access to popular processing and visualization tools and to commonly used marine datasets of the SeaDataNet community. Some key aspects such as user authentication, hosting input and output data, are based on EUDAT services, with the perspective of integration into EOSC at a later stage.

The technical infrastructure is provided by five large EUDAT computing centres across Europe, where operational environments are heterogeneous and spatially far apart. The processing tools (pre-existing as desktop versions) are developed by various institutions of the SeaDataNet community. While some of the services interact with users via command line and can comfortably be exposed as JupyterNotebooks, many of them are very visual (e.g. user interaction with a map) and rely heavily on graphical user interfaces.

In this presentation, we will address some of the issues we encountered while building an integrated service out of the individual applications, and present our approaches to deal with them.

Heterogeneity in operational environments and dependencies is easily overcome by using Docker containers. Leveraging processing resources all across Europe is the most challenging part as yet. Containers are easily deployed anywhere in Europe, but the heavy dependence on (potentially shared) input data, and the possibility that the same data may be used by various services at the same time or in quick succession means that data synchronization across Europe has to take place at some point of the process. Designing a synchronization mechanism that does this without conflicts or inconsistencies, or coming up with a distribution scheme that minimizes the synchronization problem is not trivial.

Further issues came up during the adaptation of existing applications for server-based operation. This includes topics such as containerization, user authentication and authorization and other security measures, but also the locking of files, permissions on shared file systems and exploitation of increased hardware resources.
Break up of a polar cap patch in the nightside ionosphere due to a flow channel event
Authors: Donegan-Lawley Elizabeth , Wood Alan , Dorrian Gareth , Fogg Alexandra , Yeoman Timothy , Elvidge Sean
Published: March 2020

Flow channel events have previously been observed breaking up polar cap patches on the dayside ionosphere but, to the best of our knowledge, have not been observed on the nightside. We report observations of a flow channel event in the evening of the 9th January 2019 under quiet geomagnetic conditions. This multi-instrument study was undertaken using a combination of multiple EISCAT (European Incoherent Scatter) radars, SuperDARN (Super Dual Auroral Radar Network), MSP (Meridian Scanning Photometer) and GNSS (Global Navigation Satellite System) scintillation data. These data were used to build a picture of the evening’s observations from 1800 to 2359 UT. The flow channel event lasted a total of 13 minutes and was responsible for segmenting a polar cap patch. A decrease in electron density was observed, from a patch value of 1.4x1011 m3 to a minimum value of 5x1010 m3. In addition, ion velocities in excess of 1000 ms-1 and ion temperatures of greater than 2000 K were also observed. 
Pressure effects on methane emissions from landfills
Authors: Kissas Konstantinos , Scheutz Charlotte , Kjeldsen Peter , Ibrom Andreas
Published: March 2020

Landfills are one of the major anthropogenic sources of methane (CH4) emissions to the atmosphere, even years after being inactive. Model-based estimates of CH4 emission from landfills are inaccurate due to uncertainties in the underlying assumptions regarding gas generation rates, oxidation and recovery parameters. In-situ measurement techniques are more reliable in quantifying CH4 emissions, with the tracer gas dispersion method (TDM) being one of the best-validated methods. The TDM does however not allow for continuous estimation unless a higher sampling frequency for longer measurement campaigns is being used. Field studies report short-term CH4 emission variation of several orders of magnitude, which are being driven by changes in meteorological conditions, with changes in barometric pressure being the most important. This variation makes discontinuous measurements more uncertain. In this presentation, we focus on CH4 emission dynamics under the influence of barometric pressure changes and develop a model that can explain the dynamics.

Landfill methane emissions were measured continuously with the eddy covariance method over several months in an inactive landfill (Skellingsted, Western Zealand, Denmark). The landfill is covered with an 80 cm thick soil layer and vegetated with grassland. Screenings of the site indicate a considerable horizontal heterogeneity of the emissions, which needs to be considered when interpreting continuously measured fluxes.

Measured methane fluxes ranged from 0 to 10 μmol∙m-2∙s-1. Periods with decreasing barometric pressure showed highest flux rates, while increasing barometric pressure suppressed the methane flux almost to 0 μmol∙m-2∙s-1. However, this dependency had a complex dynamic nature. In most of the cases, the responses of CH4 fluxes to pressure changes were delayed by 0 to 4 hours. We developed a model concept that is able to explain this behavior, including the pressure gradient driven advective CH4 transports through the porous soil layer above the source and diffusion between fronts of background air and landfill gas.

The general implications from this work are an estimation of the uncertainty and possibly correction of point CH4 emission measurements, e.g. with the TDM. Additionally, the increased understanding of gas transport dynamics through terrestrial landfill covers will help to evaluate the efficiency of methane emission mitigation methods that aim at increasing methane oxidation by the establishment of biocovers.
A Comparison of Radial Diffusion Coefficients in 1-D and 3-D Long-Term Radiation Belt Simulations
Authors: Drozdov Alexander , Allison Hayley , Shprits Yuri , Aseev Nikita
Published: March 2020

Radial diffusion is one of the dominant physical mechanisms that drives acceleration andloss of the radiation belt electrons due to wave-particle interactions with ultra-low frequency (ULF) waves, which makes it very important for radiation belt modeling and forecasting.  We investigate the sensitivity of several parameterizations of the radial diffusion including Brautigam and Albert (2000), Ozeke et al. (2014), Ali et al. (2016), and Liu et al. (2016) on long-term radiation belt modeling using the Versatile Electron Radiation Belt (VERB) code.  Following previous studies, we first perform 1-D radial diffusion simulations.  To take into account effects of local acceleration and loss, we perform additional 3-D simulations, including pitch-angle, energy and mixed diffusion.
Regime behaviour in the Atlantic-Eurasian Arctic related to sea ice and sea surface temperature changes
Authors: Jaiser Ralf , Akperov Mirseid , Timazhev Alexander , Romanowsky Erik , Handorf Dörthe , Mokhov Igor
Published: March 2020

Climate change in the Arctic is embedded in the global climate system leading to phenomenon like Arctic Amplification and linkages to the mid-latitudes. A major forcing emerges from changed surface conditions like declining sea ice cover (SIC) and rising sea surface temperatures (SST). We performed time-slice model experiments with the global atmosphere-only model ECHAM6 and changed SIC and SST to either high or low states, respectively. These experiments are compared to reanalysis data and analysed aiming at a separation between the influences of SIC and SST, while focusing on linkages between the Arctic and mid-latitudes in winter.

We identify five significant regimes in the Atlantic-Eurasian sector with the k-means clustering method. The regimes include different blocking patterns, situation with strong low pressure influence and the North Atlantic Oscillation in its two phases. Their frequency of occurrence is discussed for winter months. In the reanalysis we observe an increase of blocking patterns in early winter of the most recent decades. This is reproduced by our experiments with increased SST, where blocking becomes more dominant overall. In late winter, an increased frequency of occurrence of the North Atlantic Oscillation in its negative phase is observed. This and the overall temporal behaviour of regimes in recent years is best represented if SST and SIC are changed to their more recent state simultaneously. Therefore, our results suggest that increased SSTs and reduced SIC together act on observed linkages between polar regions and mid-latitudes.
Towards simulating sequences of seismic and aseismic slip across scales: Initial benchmarks and future directions
Authors: Dal Zilio Luca , Li Meng , van Dinther Ylona , Pranger Casper
Published: March 2020

Numerical simulations of the earthquake cycle have made great progress over the past decades to address important questions in earthquake physics and fault mechanics. However, significant challenges in bridging multiscale interactions between long-term tectonic deformation, aseismic fault slip, earthquake nucleation, and dynamic rupture still remain. In this study, we present results from GARNET, a newly-developed numerical library to simulate sequences of seismic and aseismic slip across scales. This finite difference code utilizes a fully staggered spatially adaptive rectilinear grid. Furthermore, it incorporates an automatic discretization algorithm and combines different physical ingredients, including a visco-elasto-plastic rheology and quasi- and fully dynamic formulation of inertial effects into one algorithm. While PETSc and Kokkos libraries are included for parallel computing, an adaptive time stepping is integrated into the algorithm to resolve both long- and short-time scales, ranging from years to milliseconds during the dynamic propagation of earthquake rupture.

 

Here we present results from two benchmarks (BP1 and BP3) based on the community code-verification effort for Sequences of Earthquakes and Aseismic Slip (SEAS) by the Southern California Earthquake Center (SCEC). BP1 benchmark is a 2D antiplane problem, with a 1D planar vertical strike-slip fault obeying rate-and-state friction, embedded in a 2D homogeneous, linear elastic half-space. The fault has a shallow seismogenic region with velocity-weakening friction and a deeper velocity-strengthening region, below which a relative plate motion rate is imposed. A periodic sequence of spontaneous, quasi-dynamic earthquakes and slow slip are simulated in the model. In the BP3 benchmark we consider full inertial effects during the dynamic rupture and we investigate its influence on earthquake behaviour and patterns. Results from these two benchmarks represent the first step towards more advanced seismic cycle models, which will help to enhance our understanding in earthquake physics.
Numerical simulation of chemical reactions occurring in fog droplets
Authors: Schmeller Gabriella , Geresdi István
Published: March 2020

Introduction

Fog provides a significant medium for chemical reactions occurring in liquid phase. Fog droplets are relatively small (5 < r < 50 µm) hence the surface-to-volume ratio is large. Through the larger overall surface the absorption of inorganic and organic gases from different sources may be enhanced. Depending on the stability of fog, the chemical processes may have more time to take place in fog droplets. Also, ground based sources of solid aerosol particles and gases may be in direct connection with fog.

Inorganic and organic components may change the pH of fog droplets and significant amount of sulphate ion can be formed due to the oxidation (e.g. by hydrogen-peroxide and ozone) of dissolved sulphur-dioxide. At the same time there are some organic components, e.g. formaldehyde, which also react with the dissolved sulphur-dioxide but produces hydroxymethanesulfonic acid (HMSA), thus decreases the possibility of producing sulphate ion through oxidation. These competitive processes are important in understanding the formation of sulphate ion in solution. In addition, the liquid phase concentration of compounds and also the sulphate ion formation strongly depends on the size of the droplets. Physical and chemical processes in fog may have an impact on both the size distribution and solubility of solid aerosol particles.

 

Numerical model

A box model with detailed microphysics and chemistry scheme with moving bin boundaries was used to simulate the following processes in fog:

(i) Formation of drops on hygroscopic aerosol particles (ammonium-sulphate). Fog is formed due to cooling rate -0.0001 K/s.

(ii) Condensational growth of drops.

(iii) Scavenging of aerosol particles by water drops due to Brownian motion and phoretic forces.

(iv) Absorption and desorption of inorganic (CO2, H2O2, O3, NH3, SO2) and organic (HCHO, HCOOH, CH3COOH) gases, dissociation, change of pH, sulphate formation (oxidation of S(IV) by hydrogen-peroxide and by ozone and reaction of formaldehyde with S(IV)).

 

Results

Significant amount of HMSA formed in drops due to the reaction of S(IV) with formaldehyde. Taking into account this reaction, the amount of S(VI) formed is decreased compared to the case when no formaldehyde was present. Formation of HMSA modifies the solubility of the solid aerosol residue after evaporation of drops.
Climatology of the relative humidity in the Carpathian Valley
Authors: Cséplő Anikó , Geresdi István , Horváth Ákos
Published: March 2020

The reports about the climate change mostly focus about the trend of the temperature or precipitation. However, the relative humidity is also an important characteristic of the atmosphere, e.g. it impacts both the cloud and fog formation. The trends of the relative humidity in the changing climate have been found to be rather uncertain.  In this research the climatological trend of the relative humidity in the Carpathian Valley was studied. Analysis of the long-term observed database from eight meteorological stations was used to present the annual and seasonal trends of the relative humidity. The annual trend was found to be between 2-3% in every meteorological station. The results show that the relative humidity has decreased every season but in autumn, when the trend of it has not been consistent. While the most significant decrease has been occurred during spring, the decrease was negligible during autumn.
The effect of surge on riverine flood hazard and impact in deltas globally
Authors: Eilander Dirk , Couasnon Anaïs , Ikeuchi Hiroaki , Muis Sanne , Yamazaki Dai , Winsemius Hessel , Ward Philip
Published: March 2020

Current global riverine flood risk studies assume a constant mean sea level boundary. In reality, high sea levels can propagate up a river leading to elevated water levels, and/or the drainage of high river discharge can be impeded by elevated sea levels. Riverine flood risk in deltas might therefore be underestimated if dynamic sea levels are ignored. This contribution presents the first global scale assessment of drivers of riverine flooding in deltas and underlines the importance of including dynamic downstream sea level boundaries in global riverine flood risk studies.

The assessment is based on extreme water levels at 3433 river mouth locations as modeled by the state-of-the-art global river routing model CaMa-Flood, forced with a multi-model runoff ensemble from the EartH2Observe project and bounded by dynamic sea level conditions from the global tide and surge model GTSM. Using this framework, we classified the drivers of riverine flooding at each location into four classes: surge dominant, discharge dominant, compound or insignificant. The classification is based on rank correlations between annual maximum riverine water levels and surge levels, and annual maximum riverine water levels and discharge. We developed a model experiment to quantify the effect of surge on flood levels and impacts.

We find that drivers of riverine flooding are compound at 19.7 % of the locations analyzed, discharge dominant at 69.2 % and surge dominant at 7.8 %. Compared to locations with either surge or discharge dominant flood drivers, locations with compound flood drivers generally have larger surge extremes, are located in basins with faster discharge response and/or flat topography. Globally, surge exacerbates 1-in-10 years flood levels at 64.0 % of the locations analyzed, with a mean increase of 13.5 cm. While this increase is the largest at locations with compound or surge dominant flood drivers, surge also affects flood levels at locations with discharge dominant flood drivers. A small decrease in 1-in-10 years flood levels is observed at 12.2 % of locations analyzed due to negative seasonal component of surge associated with dominant seasonal gyre circulations. Finally, we show that if surge is ignored, flood depths are underestimated for 38.2 million out of a total of 332.0 million (11.6 %) expected annual mean people exposed to riverine flooding.