bluuebunny/crossref_metadata_2025 huggingface dataset:
A chironomid-based reconstruction of late glacial summer temperatures in the Pareng Mountains (Romania)
Authors: Szabó Zoltán , Heiri Oliver , Darabos Gabriella , Pálfi Ivett , Molnár Mihály , Korponai János L. , Magyari Enikő K.
Published: March 2021

Late Glacial and Early Holocene summer temperatures were reconstructed based on fossil chironomid assemblages at Lake Latorica (Lacul Iezerul Latoritei; Pareng Mountains, 1530 m a.s.l.) with a joint Norwegian – Swiss transfer function, providing an important addition to the late glacial quantitative climate reconstructions from eastern-central Europe. The reconstructed pattern of the Late Glacial faunal and chironomid-inferred temperature changes in Lake Latorica shows some differences from the NGRIP δ18O record and other European chironomid-based reconstructions; however, it is consistent with the chironomid results of Lake Brazi from the neighbouring Retyezat Mountains (1740 m a.s.l.). Our reconstruction shows that the summer air temperature at Lake Latorica increased by ~ 3°C at the Oldest Dryas/Bølling transition (GS-2/GI-1) and reached 8.1-10.8°C during the Late Glacial interstadial. The Younger Dryas (GS-1) climate reversal in the chironomid-based temperature reconstruction is shown by only a weak decrease (~1°C), while slow temperature increase (9.7–11°C) is observed in the second half of the period. At the Holocene transition temperature increase of nearly 2°C was observed in the reconstruction. Before the Preboreal Oscillation (PO) the mean summer air temperature in the Early Holocene was 12.5°C. During PO the temperature reconstruction shows a decrease of 1.8°C. This cold event coincides with cooling in the Greenland ice core records and other European temperature reconstructions. After the Preboral oscillation the summer air temperatures increase to ~12.8°C in the Early Holocene.
Ammonia emissions from cattle slurry and digestates
Authors: Efosa Norah , Krause Hans-Martin , Häni Christoph , Six Johan , Bünemann Else
Published: March 2021

The recycling of organic waste in biogas plants is proposed as a measure to close nutrient cycles and possibly reduce nitrogen losses such as nitrous oxide emissions and nitrate leaching. Ammonia volatilization after fertilizer spreading is yet another nitrogen loss pathway which is often understudied and not yet fully understood but the knowledge is needed in order to optimize fertilizer management. We therefore aimed to quantify the volatilization of ammonia after the trail-hose application of digestates compared to cattle slurry. We hypothesize that digestates have larger and longer lasting nitrogen losses via ammonia volatilization due to higher NH4+ contents and pH values compared to fresh manure. In this project, digested and un-digested organic fertilizers were applied twice per year in a 2.5-years field experiment with three consecutive arable crops (maize, winter wheat and winter barley) under organic farming. We used Automated Low Cost Impinger Systems to measure ammonia emissions after fertilizer application. The emissions were then modeled using the backwards Langrangian stochastic dispersal model with respect to wind conditions. A preliminary presentation of the data indicates that ammonia emissions from the cattle slurry, slurry-based digestate, and industrial digestate are alternately higher or lower. In 2018, emissions from cattle slurry tended to be lower than those from slurry-based digestate and industrial digestate, while in 2019 and 2020 all three liquid organic fertilizers had similar emissions. In the measurement period after the second fertilizer application in 2018, which took place at the end of May, conspicuously high emissions were measured. This can be explained by the high temperatures during this period. Adaptive strategies in fertilizer management should thus consider reduced inputs of organic fertilizers  during warm periods.
Investigating the internal lithological structure and rock magnetic signature of Heinrich Event layers at SE Grand Banks Slope, Newfoundland
Authors: Bukar Shettima , von Dobeneck Tilo , Lisker Frank
Published: March 2021

Periodic mass discharges of icebergs from the Laurentide ice-sheet into the North Atlantic Ocean during the last glacial period deposited abundant ice-rafted detritus (IRD) accumulated in sequences of typically six major Heinrich Event layers, each with some tens of cm thickness, at all eastern slopes of the Grand Banks submarine platform of Newfoundland. Compositionally, it is well established that these IRD layers consist of varied rock contents emanating from distinct, but not yet clearly defined bedrock provinces of the Canadian Shield. The, most prominently reported constituent is detrital dolomite, but the entire lithological range of the IRD is much broader. Rock magnetic records, e.g. magnetic susceptibility logs of SE Grand Banks cores, therefore depict complex and partly repeating internal substructures across the Heinrich Event layers owing to distinct successions in IRD lithology over the course of every mass calving event.

We investigated IRD sieve fractions (1mm – 4cm) of the entire glacial section (550–1054 cm) of SE Grand Banks slope gravity core GeoB 18530-1, sampled in 2.3 cm steps. Therefrom, we identified and classified distinct IRD rock types as well as monocrystalline rock-forming mineral particles, for which we established so far 24 well-defined lithological categories of sedimentary, igneous and metamorphic origin. This initial identification of IRD lithology was performed based on all available visual criteria including texture (crystallinity, grain-size), color and translucency (mineralogy), hardness and surface structures (e.g., cleavage) using a binocular microscope. This rock type classification is now being substantiated by polarized light microscopy of exemplary thin sections created from larger IRD clasts.

To established cumulative rock magnetic fingerprints of all IRD magnetic mineral assemblages, isothermal remanent magnetization acquisition curves of all sieve fractions as well as individual specimens of all the classified rock types have been measured. These records systematically revealed higher concentrations of magnetic minerals at the tops and bottoms of most Heinrich Event layers and also clear variations in coercivity spectra. This finding is mirrored by the IRD rock count records, where magmatic rock types predominate mostly at Heinrich Event layer boundaries. Preferred deposition of these IRD rock types during the initiation and ending of events and their variation from older to younger events,- highlight repetitive patterns in the cyclic Laurentide ice-sheet collapses to be further explored.
Winds and tides of the Antarctic mesosphere and lower thermosphere: One year of meteor-radar observations over Rothera (68°S, 68°W) and comparisons with WACCM and eCMAM
Authors: Dempsey Shaun M , Hindley Neil , Moffat-Griffin Tracy , Wright Corwin , Smith Anne , Du Jian , Mitchell Nicholas
Published: March 2021

Tides are crucially important to the dynamics of the MLT. Therefore, models which aim to span the whole atmosphere must be capable of reproducing these tides, making observations of tides vital to constrain model development. Here, we present a novel climatology of 12- and 24-hour tides, measured at heights of 80–100 km by a meteor radar over the Rothera Station, Antarctica (68°S, 68°W). We use these observations to test two GCMs: WACCM and eCMAM (the latter 24-hr only). Our observations reveal large-amplitude tides with strong seasonal variability. The 12-hour tide maximises around the equinoxes and the smaller-amplitude 24-hour tide maximises in summer.  WACCM reproduces 12-hour tidal amplitudes at 80 km well, but not their increase with height or equinoctial maxima, and reproduces the observed small variation in 24-hr tidal amplitude with height well but with anomalously-large amplitudes. eCMAM reproduces observed 24-hr tidal amplitudes and their small variation with height. Our observations also reveal sizeable day-to-day variability in tidal amplitude at planetary wave periods, which we suggest originates from non-linear tidal/planetary-wave coupling. Furthermore, we see notable differences between observed and model background winds which are not reproduced in the models; we propose these differences may arise from the lack of in-situ gravity-wave sources in the models.
Model evaluation expectations of European ESM communities: results from a survey
Authors: Servonnat Jerome , Guilyardi Eric , Stott Zofia , Serradell Kim , Lauer Axel , Zimmerman Klaus , Adloff Fanny , Greening Marie-Claire , Kazeroni Remi , Vegas Javier
Published: March 2021

Developing an Earth system model evaluation tool for a broad user community is a real challenge, as the potential users do not necessarily have the same needs or expectations. While many evaluation tasks across user communities include common steps, significant differences are also apparent, not least the investment by institutions and individuals in bespoke tools. A key question is whether there is sufficient common ground to pursue a community tool with broad appeal and application.

We present the main results of a survey carried out by Assimila for the H2020 IS-ENES3 project to review the model evaluation needs of European Earth System Modelling communities. Interviewing approximately 30 participants among several European institutions, the survey targeted a broad range of users, including model developers, model users, evaluation data providers, and infrastructure providers. The output of the study provides an analysis of  requirements focusing on key technical, standards, and governance aspects.

The study used ESMValTool as a  current benchmark in terms of European evaluation tools. It is a community diagnostics and performance metrics tool for the evaluation of Earth System Models that allows for comparison of single or multiple models, either against predecessor versions or against observations. The tool is being developed in such a way that additional analyses can be added. As a community effort open to both users and developers, it encourages open exchange of diagnostic source code and evaluation results. It is currently used in Coupled Model Intercomparison Projects as well as for the development and testing of “new” models.

A key result of the survey is the widespread support for ESMValTool amongst users, developers, and even those who have taken or promote other approaches. The results of the survey identify priorities and opportunities in the further development of the ESMValTool to ensure long-term adoption of the tool by a broad community.
Microfracture evolution leading to catastrophic failure observed by hearing and seeing
Authors: Mangriotis Maria-Daphne , Curtis Andrew , Cartwright-Taylor Alexis , Andò Edward , Main Ian , Bell Andrew , Butler Ian B. , Fusseis Florian , Rizzo Roberto , Ling Martin , Marti Sina , Leung Derek Doug Vick , Singh Jonathan , Magdysyuk Oxana
Published: March 2021

Catastrophic failure is a critical phenomenon present in Earth systems on a variety of scales, and is associated with the evolution of damage leading to system-size failure. Laboratory testing of rock failure permits characterization of fracture network evolution at the micro-scale to understand the interaction of cracks, pores and grain boundaries to an applied stress field, and the relationship between deformation and seismic response. Previous studies have relied on acoustic emissions (hearing) or X-ray imaging (seeing) to study the process of localization, which involves spontaneous self-organization of smaller cracks along faults and fractures on localised zones of deformation. To combine hearing and seeing of the microscopic processes and their control of system-sized failure, a novel x-ray transparent cell was used for deformation experiments of rock samples, which permits integration of acoustic monitoring with fast synchrotron x-ray imaging. To increase temporal characterization of damage beyond the temporal resolution of the fast 3D synchrotron system, acoustic emission (AE) feedback control was used to regulate the applied stress and slow down the deformation processes. As a result, there is increased temporal resolution of the incremental deformation between successive x-ray scanned states allowing synchronized comparison of acoustic emissions to x-ray scans. Here, we present the seismic analysis used to characterize the velocity evolution of the rock samples, and the location and characteristics of individual AE events in relation to microscopic deformation processes. Time-lapse velocity measurements are linked to internal stress changes and structural damage corresponding to seismic and aseismic deformation processes, while acoustic emissions are a direct indication of local cracking.  We show that we can successfully locate AE events in 3D using only two sensors on either end of the sample, based on ellipsoid mapping, and x-ray image to event correlation. We explore temporal and spatial statistics of AE signatures and how those are linked to the strain field in the samples measured with incremental digital volume correlation between pairs of recorded x-ray tomograms. The direct observation of AE and X-ray images enables quantification of relevant seismic (local cracking leading to AE) to aseismic (elastic loading and silent irreversible damage) processes, with information extracted over fine temporal resolution throughout the deformation process through the AE-feedback control.
Tree model with drag, transpiration, shading and deposition: Identification of cooling regimes and large-eddy simulation
Authors: van Reeuwijk Maarten , Grylls Tom
Published: March 2021

Trees play an important role in the urban heat island effect and urban air quality due to their impact on the transfer of radiation, momentum, heat, moisture and pollution. However, the effects of trees are hard to quantify due to their complex interactions with urban surfaces and the turbulent atmosphere overhead.

We present a complete tree model for large-eddy simulations (LES) that represents the effects of trees on drag, transpiration, shading and deposition at resolutions of O(1 m, 0.1 s) whilst minimising the number of model parameters. The tree model avoids the necessity to resolve the leaf temperature via a derivation of the Penman-Monteith equation and distinguishes between cooling via transpiration and shading. The latent heat flux is further broken down into radiative and advective components in order to better understand the mechanism behind transpirational cooling (e.g. the ‘oasis’ effect).

The new tree model is investigated analytically to provide insight into tree cooling regimes, and is applied to field studies to contextualise the analysis. The combined cooling effect of trees due to transpiration and shading processes can be reduced to a four-dimensional parameter space. The net tree cooling (NTC) and tree cooling ratio (TCR) parameters are defined to enable a systematic categorisation of the thermal effect of a tree into five regimes: net heating, net reduction (shading dominated), net reduction (transpiration dominated), net cooling (shading dominated) and net cooling (transpiration dominated). Existing parameterisations for tree cooling are reviewed, illustrating their limitations and highlighting the need for complete models to determine tree cooling.

The tree model is implemented into the LES model uDALES. The drag and canopy energy balance models are validated, and results are presented for domains that are 1) fully covered by trees; 2) partially covered by trees; and 3) have a single line of trees. These simulations provide physical insight into the effect of trees on the microclimate and provide evaluation data for future studies.
Statistical evaluation of the correlation pattern between rising global temperature and stable water isotopes in precipitation.
Authors: Ditzel Lukas , Schramm Jonas , Gaßmann Matthias
Published: March 2021

Statistical evaluation of the correlation pattern between rising global temperature and stable water isotopes in precipitation.

Lukas Ditzel, Jonas Schramm, Matthias Gassmann

Department of Hydrology and Substance Balance, University of Kassel, Kurt-Wolters-Strasse 3, 34125 Kassel, Germany

 

Stable water isotopes in precipitation on the northern hemisphere are usually following a predictable pattern throughout the year, with high amounts in summer and low amounts of deuterium and 18O in the winter season. Backed by a richness of available date from the International Atomic Energy Agency (IAEA), one can mostly expect an annual sinusoidal form of isotope data, when looking at data for a certain region in the northern hemisphere.

Since the driving factor for isotopic enrichment or depletion is isotopic fractionation, the seasonal behavior is strongly correlated to air-temperature. The correlation between temperature and fractionation is strong enough to explain most of the greater deviations from the sinusoidal form like in arid regions. It occurs that globally rising temperatures, initiated by climate change, should have an impact on the sinusoidal form of the stable water isotope time series. We assumed, that rising temperatures will lead to higher contents of deuterium and 18O in the precipitation of the northern hemisphere. Due to the availability of data and the long time series, which are needed for robust answers, we focused our work on European and North-American data. First analyses showed a positive correlation between rising air-temperatures and isotopic content, but not all regions. Other effects like the elevation- and continental-effect were dampening the effect of rising global temperatures, especially in coastal regions or islands such as Ireland. More continental regions, however, are showing a rise for isotopic enrichment in precipitation. We analyzed this trend by the calculation of the trend-components of these time-series via Loess and validated them by using the Mann-Kendall-Test. Furthermore, we separated sets of data into monthly clusters and looked for rising temperature trends in every month over the size of the available time series. This second analysis was performed for the time series from weather stations in Berlin, Vienna and Krakow covering almost 40 years of monthly isotope data.
Some illustrations of large tectonically driven climate changes in Earth history
Authors: Zhang Zhongshi , Ramstein Gilles
Published: March 2021

Nearly A century ago the pioneering book published in 1924 “Die Klimate der geologischen Vorzeit “ explained by plate motion the evolution of vegetation revealed in sedimentary records. Nevertheless, they did not invoke climate changes. In the second part of the 20th century the intricate relationship between tectonics, long-term carbon cycle and climate was depicted by James G. C. Walker (1981). Since these major steps, climate modeling of the Earth system kept on improving and including more and more components and processes to enable the investigation of deep time periods using general circulation model that can account for atmosphere and ocean dynamics. Here we illustrate long but drastic climate changes clearly related with tectonics, through three different examples:

1)  The crucial role of paleogeography (continental distribution) to explain the drawdown of atmospheric carbon dioxide and the huge glaciation associated that occured during the Neoproterozoic period.

2)  The shrinkage of large epicontinental Paratethys that covered a large part of Eastern Europe and Western Asia and its impact on both monsoonal systems (African and Asian) since 40 Ma.

3) The large impact of mountain range uplifts since Eocene both in Asia (Tibetan Plateau and Himalaya) and in Africa (buildup of the rift), on atmosphere and ocean dynamics.

These studies not only allow for testing the ability of Earth system models to capture long term changes of Earth climate, but they pinpoint the pivotal role tectonics played in shaping the long-term evolution of atmospheric CO2 and monsoon patterns.
Compound Events of Tropical Cyclone and Flooding in India
Authors: Rajeev Akshay , Mishra Vimal
Published: March 2021

India is severely affected by tropical cyclones (TC) each year, which generates intense rainfall and strong winds leading to flooding. Most of the TC induced floods have been attributed to heavy rain associated with them. Here we show that both rainfall and elevated antecedent soil moisture due to temporally compounding tropical cyclones cause floods in the major Indian basins. We assess each basin's response to observed TC events from 1980 to 2019 using the Variable Infiltration Capacity (VIC) model. The VIC model was calibrated (R2 > 0.5) and evaluated against observed hourly streamflow for major river basins in India. We find that rainfall due to TC does not result in floods in the basin, even for rainfall intensities similar to the monsoon period. However, TCs produce floods in the basins, when antecedent soil moisture was high. Our findings have implications for the understanding of TC induced floods, which is crucial for disaster mitigation and management.
Modelling high-latitude explosive eruptions and their atmospheric and environmental impacts
Authors: Fuglestvedt Herman , Zhuo Zhihong , Sigl Michael , Toohey Matthew , Mills Michael , Krüger Kirstin
Published: March 2021

Large explosive volcanic eruptions inject sulphur into the stratosphere where it is converted to sulphur dioxide and sulphate aerosols. Due to atmospheric circulation patterns, aerosols from high-latitude eruptions typically remain concentrated in the hemisphere in which they are injected. Eruptions in the high-latitude Northern Hemisphere could thus lead to a stronger hemispheric radiative forcing and surface climate response than tropical eruptions, a claim that is supported by a previous study based on proxy records and the coupled aerosol-general circulation model MAECHAM5-HAM. Additionally, the subsequent surface deposition of volcanic sulphate is potentially harmful to humans and ecosystems, and an improved understanding of the deposition over polar ice sheets can contribute to better reconstructions of historical volcanic forcing. On this basis, we model Icelandic explosive eruptions in a pre-industrial atmosphere, taking both volcanic sulphur and halogen loading into account. We use the fully coupled Earth system model CESM2 with the atmospheric component WACCM6, which extends to the lower thermosphere and has prognostic stratospheric aerosols and full chemistry. In order to study the volcanic impacts on the atmosphere, environment, and sulphate deposition, we vary eruption parameters such as sulphur and halogen loading, and injection altitude and season. The modelled volcanic sulphate deposition is compared to the deposition in ice cores following comparable historical eruptions. Furthermore, we evaluate the potential environmental impacts of sulphate deposition. To study inter-model differences, we also compare the CESM2-WACCM6 simulations to similar Icelandic eruption experiments simulated with MAECHAM5-HAM. 
Land-atmosphere coupling during compound extreme heat and drought events in the LUCAS experiment: a new coupling metric for climate extremes
Authors: Cardoso Rita M. , Lima Daniela D. C. A. , Soares Pedro M. M. , Rechid Diana , Breil Marcus , Coppola Erika , Davin Edouard , Hoffmann Peter , Jach Lisa , Katragkou Eleni Katragkou , Meier Ronny , Mooney Priscilla A. , de Noblet-Ducoudré Natalie , Panitz Hans-Juergen , Sofiadis Ioannis , Strada Susanna , Strandberg Gustav , Tölle Merja , Warrach-Sagi Kirsten
Published: March 2021

Land-atmosphere energy and water exchanges are fundamentally linked to soil-moisture. The distribution of the planets’ biomes hinges on the surface-atmosphere coupling since soil moisture and temperature feedbacks have a strong influence on plant transpiration and photosynthesis. Land use/land cover changes (LUC) modify locally land surface properties that control the land-atmosphere mass, energy, and momentum exchanges. The impact of these changes depends on the scale and nature of land cover modifications and is very difficult to quantify. However, large inconsistencies in the LUC impacts are observed between models, highlighting the need for common LUC across a large ensemble of models. The Flagship Pilot Study LUCAS (Land Use & Climate Across Scales) provides a coordinated effort to study LUC using an ensemble of regional climate models (RCMs). In the first phase of the project 3 experiments were performed for continental Europe: EVAL (current climate); GRASS (trees replaced by grassland) and FOREST (grasses and shrubs replaced by trees).  An analysis of the energy and moisture balance for the three experiments is performed, focusing on the relationship between the fluxes partitioning, heat waves and droughts. To better asses the link between extreme temperatures and soil moisture or evapotranspiration, a new coupling metric for short time scales is proposed, the Latent Heat Flux-Temperature Coupling Magnitude (LETCM). This new metric is computed for a specific period, considering the positive temperature extremes and the negative latent heat flux extremes. Areas with positive magnitude values imply higher temperature anomaly, due to a negative latent heat flux anomaly. This new metric only considers periods of strong coupling, with positive signals in areas of high temperatures and evaporative stress, allowing for the detection of events that are extreme for energy and water cycle. Concurrently, a new decile based normalised drought index is used to examine the concurrent heat extremes and droughts. The analysis focuses on the three experiments revealing that the number, amplitude and spatial distribution of compound extreme heat and drought is highly model dependant. The impact of afforestation or deforestation is not consistent across models.

Acknowledgements

 The authors wish to acknowledge project LEADING (PTDC/CTA-MET/28914/2017) and FCT - project UIDB/50019/2020 - Instituto Dom Luiz.
Experimental study of Wave-turbulence interaction
Authors: Smeltzer Benjamin K. , Ellingsen Simen Å.
Published: March 2021

Turbulence is ubiquitous in the topmost skin of the ocean, where it interacts with surface waves. Rapid distortion theory predicts that wave motion will increase turbulent energy, leading to a dissipation of waves [1]. Waves are believed to contribute significantly to the turbulence in the ocean mixed layer, yet field measurements are unable to validate or distinguish between models and theories [2].

In this work we study the modification of turbulence by surface waves using experimental measurements of turbulent flows in the presence of waves, in a laboratory set-up acting as a small-scale model of the water side of the ocean surface layer. Turbulent Langmuir numbers comparable to those in the ocean are achieved, ensuring scalability. Particle image velocimetry (PIV) measurements were performed in a large water channel wherein mechanically generated waves may propagate on a current. An active grid at the inlet allowed the turbulence intensity and mean flow to be tailored independently. The flow field was measured in the streamwise-vertical plane for various flow cases and waves of varying steepness and frequency. The turbulence characteristics are compared to cases without waves to study the impact of the waves on the turbulence and the results are discussed considering predictions from rapid distortion theory.

 

[1] Teixeira M. and S. Belcher 2002 “On the distortion of turbulence by a progressive surface wave” Journal of Fluid Mechanics  458 229-267.

[2] D’Asaro E.A. 2014 “Turbulence in the upper-ocean mixed layer” Annual Reivew of Marine Sciences 6 101-115.
Climate services for the retail sectors: the Filomena’s case
Authors: Martínez Botí Albert , Palma Lluís , Roura Francesc , Manrique-Suñén Andrea , González-Reviriego Nube , Marcos Raül , González Sergio , López Antonio , Soret Albert
Published: March 2021

The need of filling the gap between medium-range weather (up to 10-15 days) and seasonal forecasts (3–6 months) has led to several operational weather and climate centres to include the subseasonal forecasting in their predictions. Although this kind of information is starting to be explored by some stakeholders, such as renewable energy, water management, agriculture or disaster prevention, there are still much more sectors who can exploit this information. In this contribution, we will present how this type of climate information is used by the retail sector, in particular by a well known French sporting goods retailer within their operations over Spain. Having reliable climate forecasts weeks in advance would allow to manage the stock, redistribute it along with different warehouses and take different advertising campaigns and prices policies to avoid both the extra-cost that implies keeping what is not sold and running out of products. A recent proof of the influence of climate on sporting goods sales has been evidenced by the large increase in sales of mountain and snow equipment during Filomena’s episode, which violently hit the south-west, centre and north-east of the Iberian Peninsula in January 2021. Trustworthy subseasonal forecasts could be equally useful during other times of the year to make some decisions, such as extending or shortening the summer sports season. To illustrate the potential of these types of climate predictions, a case study for the Filomena event in January 2021 is presented. The sub-seasonal NCEP-CFS v2 prediction system has been used to compute the probability of each tercile category for surface temperature (above-normal, below-normal or normal - where normal is the average over a reference period). Forecasts for weekly temperature were calibrated using as reference the ERA-5 reanalysis dataset and the regions with negative skill were masked. It is interesting to point out how the predictions issued three weeks in advance already indicated that surface temperature would be below normal over Spain.
Opening of the north-eastern Atlantic and onshore mountain rise controlled by Fennoscandian deep structure
Authors: Makushkina Anna , Tauzin Benoit , Miller Meghan , Tkalcic Hrvoje , Thybo Hans
Published: March 2021

Large-scale topography is thought to be mainly controlled by active tectonic processes. Fennoscandia is located far from any active tectonic setting and yet includes a mountain range along its passive North Atlantic margin. Models proposed to explain the origin of these enigmatic mountains are based on glacial isostatic adjustments, delamination, long-term isostatic equilibration, and dynamic support from the mantle, yet no consensus has been reached. We show that topography along the continental margin of Fennoscandia may be influenced by its deep structure. Fennoscandia formed by amalgamation of Proterozoic and Archean continental blocks; using both S- and P-receiver functions, we discovered that the Fennoscandian lithosphere still retains the original structural heterogeneity and its western margin is composed of three distinct blocks. The southern and northern blocks have relatively thin crust (~40-45 km), while the central block has thick crust (~60 km) that most likely was formed by crustal stacking during the Proterozoic amalgamation. The boundaries of the blocks continue into the oceanic crust as two major structural zones of the North-East Atlantic, suggesting that the Fennoscandian amalgamation structures determined the geometry of the ocean opening.  We found no evidence for mountain root support or delamination in the areas of high topography that could be related with mountain formation. Instead, our results suggest that both crustal and lithospheric heterogeneity of Fennoscandia along the continental margin might have a control on geodynamic forces that support the rise of Scandinavian mountains. 
Tsunami Ray Tracing Method for Shortest Travel-Time Path
Authors: Ho Tung-Cheng , Watada Shingo , Satake Kenji
Published: March 2021

We propose a ray-tracing method to solve the two-point boundary value problem for tsunamis based on the long-wave theory. In the long-wave theory, the tsunami wave velocity is proportional to the square root of water depth, which is available from global bathymetric atlases. Our method computes the shortest travel times starting from each of the two given points and calculates the local ray direction to trace the ray path. We utilize an explicit, non-iterative tracing scheme that exhibits robust results and applies to any tsunami-accessible locations, and the global-shortest travel-time path is derived. In simple and real bathymetry cases, our method demonstrates stable results with neglectable low uncertainties. The ray-tracing method is then applied to analyze the path of tsunamis from different directions to four important bays in Japan. The result shows that tsunami ray paths are significantly influenced by local bathymetry, and some crucial structures, such as trench and trough, behave as the primary routes of this region. Deploying stations near these routes will be most beneficial for tsunami early warning. The existing tsunami-observing system off the Honshu area works well for tsunamis from the east side but slightly deficient for tsunamis from the west side. The far-field ray tracing shows that tsunamis traveling from Chile to Japan through two main routes—one via north Hawaii and the other via the south— depending on the location of the source.
Mineral Prospectivity Modeling using AVIRIS-NG VNIR-SWIR data and Gravity data for Gold-Sulphide mineralization in parts of GADAG schist belt, Karnataka, India 
Authors: Rani Komal
Published: March 2021

Gadag schist belt, India is known for sulphide-gold mineralization. In the study area mineralization is controlled structurally and lithologically. In this context, Airborne Visible-Infrared Imaging Spectrometer - Next Generation (AVIRIS-NG) Visible Near InfraRed (VNIR) - Shortwave Infrared (SWIR) bands were utilized to derive alteration zones and structures present in the study area. Lithological boundaries have also been updated using AVIRIS-NG VNIR-SWIR bands derived images enhancement products i.e. Minimum Noise Fraction (MNF) and False Colour Composite (FCC). Further, image spectra of alteration zones (Hydrous mineral etc.) derived from AVIRIS-NG calibrated VNIR-SWIR bands were compared with the standard corresponding reference library spectra (USGS, JPL spectral library). These image spectra have been utilized to demarcate the alteration zones using the Matched Filtering spectral mapping method. Structures were demarcated using high pass (HP) filtered image and FCC images. Low pass (LP) filter image and along with MNF & FCC image composite were utilized to update the lithological boundaries in the study area.

Ground gravity data has also been processed to derive the subsurface evidences relevant to the deposit in the present study area. Subsurface structures which are responsible for the transportation of mineral rich fluid in the near subsurface are delineated using the gravity data derived products. Apart from this, basement depths are also derived from the gravity data which are being utilized for the validation as well as to further precise the locations of mineral deposits.  These subsurface structures (gravity data), lithology, lineament density and alteration zones are very important evidential layers which have been integrated using fuzzy logic integration techniques to identify potential zones of gold-sulphide mineralization in the present study area. The prospective zones are validated using the secondary data and basement depth derived from the gravity data.

For similar kind of gold-sulphide mineralization, AVIRIS-NG data and Gravity data can be used to derive the important evidential layers in any part of the world. There are only few studies where such integration approach has been utilized to explore new potential zones of gold sulphide mineralization. 

Keywords: AVIRIS-NG, VNIR-SWIR, alteration, MNF, FCC, Gravity, Basement Depth
A new physically based parameterization for wind-wave stresses under strong winds
Authors: Fernandes Royston , Bouin Marie-Noelle , Redelsperger Jean-Luc
Published: March 2021

The ability to estimate flux exchanges between the sea-surface and the atmosphere has tremendous importance on weather prediction and climate simulations. These exchanges are influenced by wave processes - growth and decay, and turbulent interactions at the air-sea interface. For momentum, the ensemble of these exchanges is presented as the sea-surface drag (Cd), which increases with (10-m high) wind intensity till about 20-30 m/s, and decreases thereafter. The reason for this decrease remains less understood, mainly due to (i) our inability to explicitly measure the individual wind-wave exchanges, and (ii) the inability of existing semi-empirical parameterizations to explain the Cd behavior. To this end, we developed a physically based stress parameterization for a coupled wind-wave model, capable of reproducing both wave growth and wave breaking stresses at the air-sea interface. The advantage of such a numerical approach, over field experiments, is that it allows us to investigate the different process, under different constraining environments, in-order to disentangle the factors in play on Cd. Our coupled model enables a two-way interaction between the ocean-waves and turbulent flow. and can simulate (i) the main turbulent eddies of the air-flow, and (ii) the wind-wave interactions. After evaluating the model against published field experiments we use it to explore the impact of wave growth and wave-breaking on the Cd under strong winds. Our results demonstrate that under strong winds the air-flow gets separated from the sea-surface, a process associated with wave-breaking, resulting in the turbulent flow sensing a smoother surface as against an actually rough sea surface, thereby decreasing Cd. Finally, our model allows us to investigate the sensitivity of Cd to different influencing factors under strong winds.
Secondary organica aerosol formation from the reactions of 2,5-dimethylfuran with OH radicals and ozone
Authors: Rodriguez Cervantes Ana , Tajuelo Diaz-Pavón Mercedes , Rodriguez Rodriguez Diana , Escalona Verbo Alba , Viteri Tovar Gabriela , Aranda Rubio Alfonso , Diaz de Mera Yolanda
Published: March 2021

Biomass is a significant renewable energy source and is expected to grow in importance in the transition away from fossil energy sources at a relatively low cost. Lignocellulosic biomass, which is the most abundant biomass, has critical importance as sustainable production of chemicals and fuels. Catalytic production methods of converting lignocellulosic biomass into furan derivatives have been improved significantly. One of these furan derivatives, 2,5-dimethylfuran (2,5-DMF), has attracted interest as a potential biofuel due to its physicochemical properties, in some aspects better than gasoline and ethanol, such as the low pollutant emissions in its combustion. However, before 2,5-DMF can be accepted as an alternative transport fuel, some outstanding problems, as its atmospheric fate, must be resolved.

2,5-DMF can be degraded by the main tropospheric oxidants, resulting in furan derivatives such as furanones which are efficient precursors of SOA. To this end, the present study had the aim of analyzing the OH radical photooxidation and ozonolysis of 2,5-DMF, characterizing the conditions that lead to the formation and growth of new particles. Factors such as relative humidity (RH), NOx and SO2 level and pre-existing inorganic seed particles, which could influence in SOA formation, has been assessed. The study was carried out in two different chambers at (296±1) K and atmospheric pressure. Results for OH-photooxidation indicate that SOA yields decrease (from 6.2 to 0.4%) with the rise of 2,5-DMF concentration (from10 to 1000 ppb). In the absence of NOx and under high relative humidity (RH) conditions (60%), higher aerosol yields are favored. SOA formation is dependent on the initial seed surface for two kinds of inorganic seed particles ((NH4)2SO4 and CaCl2), being the effect slightly greater for CaCl2. The ozonolysis only generates particles in the presence of SO2 and the increase of relative humidity from 0 to 15% lowers the particle number and particle mass concentrations. The water-to-SO2 rate constant ratio of the Criegee intermediate was derived from the SOA yield in experiments with different relative humidity values.

The obtained results provide detailed daytime chemistry about SOA formation from 2,5-DMF oxidation and improves our understanding of the chemical evolution of biomass burning plumes. Moreover, these results could be integrated into air quality simulation models, especially in developing countries which are suffering severe fine particulate matter pollution.
Growing a diamond open access community initiative: Volcanica 3 years on
Authors: Wadsworth Fabian , Farquharson Jamie , Kushnir Alexandra , Heap Michael , Kennedy Ben , Chevrel Oryaëlle , Williams Rebecca , Delmelle Pierre
Published: March 2021

The case for open access research is well established. At the core of the pro-openness argument is a philosophy that it is good if research outputs are widely accessible, breaking down the walls that stand between the world of research and the public. Moreover, openness ensures that scientists can access resources worldwide, even if their institutions cannot afford subscription fees, thereby breaking down economic barriers and access disparities that exist globally. In large part, publishers and publications are adopting this philosophy, and ensuring that the costs of publication are covered by charging them to the authors (via Article Processing Charges, or APCs) rather than the readers of research – this is the ‘gold’ openness model. However, these charges for publication are often very high, which discourages submission to gold open access forums and maintains an academic environment that favours the older ‘subscription’ models of publication.

At the journal Volcanica, we have found a way to remove both costs – costs to readers and costs to authors – by building a community journal that maintains exceptionally low running costs, paid for by a university press publisher – this is the ‘diamond’ openness model. We can achieve this by relying on volunteer time provided at no cost. In this presentation, we explore the current state of our journal three years after the publication of our first article. We survey the challenges faced by Volcanica as we grow, handle more submissions, and expand our reviewing, typesetting, and back-end work-flow. To meet these challenges, we have expanded our technical and editorial personnel.

Here we explore the growth challenges that are still to come, and compare our volunteer model with the model of the ‘academic society journal’, in which relatively minimal staff costs are paid for by a mixed model. The mixed model is still driven by article processing charges, but keeps those costs comparatively low, and offers fee-waivers on a needs basis, acknowledging that not all authors are well-funded. In doing so, we take a nuanced approach to the realities of growing a community-led endeavour, and examine the extent to which our model could be scaled to the size of the leading journals in our field. While we do not reach a definitive conclusion as to the role that Diamond publishing models will play in the future landscape of research dissemination, we hope that the presentation of our experiences is informative to the geo-scientific community, especially as new ‘diamond’ open journals – Seismica and Tektonika – are slated for launch in the coming years.
Ice nucleation by glaciogenic dust and cloud climate feedbacks
Authors: Sanchez-Marroquin Alberto , Arnalds Olafur , Baustian-Dorsi Kelly J. , Browse Jo , Dagsson-Waldhauserova Pavla , Harrison Alexander D. , Matters Elena C. , Pringle Kirsty J. , Vergara-Temprado Jesus , Burke Ian T. , McQuaid Jim B. , Carslaw Ken S. , Murray Ben J.
Published: March 2021

Although most of the dust present in the atmosphere originates from low-latitude arid deserts, it has been increasingly recognised that there are significant sources of High-Latitude Dust (HLD) in locations such as Iceland, Greenland, North American Arctic or North Eurasia [1]. The emission, transport and deposition of HLD can interact with the atmosphere, cryosphere and the marine ecosystem in several ways. Particularly, HLD has the potential to act as significant source of atmospheric Ice-Nucleating Particles (INP), competing with other sources such as dust and other INP types from lower-latitude arid sources [2, 3]. INPs are the fraction of aerosol particles that can trigger ice-formation in supercooled water droplets, that otherwise would remain unfrozen until temperatures of about -36 oC.

Ice formation initiated by the presence of INPs dramatically affects the amount of solar radiation reflected by clouds containing both liquid water and ice, known as mixed-phase clouds. However, ice-related processes in mixed-phase clouds such as the INP concentration are commonly oversimplified in most climate models, which leads to large discrepancies in the amount of water and ice that the models simulate at mid- to high-latitudes [4]. These present-day divergences in simulated mixed-phase clouds lead to a large uncertainty in the cloud climate feedback. This feedback is associated to the fact that mid- to high-latitude mixed-phase clouds dampen a part of the of the global temperature rise associated with greenhouse gases [5] [6].

Here we will explain the importance of understanding the chemical and ice-nucleating properties of HLD, as well as how it is emitted, transported and deposited for the cloud climate feedback. We will present new results from aircraft studies of the ice nucleating ability of HLD as well as modelling work which shows that this dust can be transported to altitudes and regions where it has the potential to influence mixed-phase clouds and climate.
High-resolution PM2.5 forecasting using CAMS predictions, low-cost sensors and ensemble techniques
Authors: Pappa Areti , Kioutsioukis Ioannis
Published: March 2021

Expediting urbanization has triggered an increase in cardiopulmonary diseases attributable to fine-particulate air pollution. Air Quality models simulate the dilution and dispersion of air pollutants that affect the atmosphere, contributing crucially to the comprehension of its processes. Air quality forecasts produced by the Copernicus Atmosphere Monitoring Service (CAMS) provide open access to accurate and reliable information but in a coarse resolution. Data-driven models can downscale the forecasts from deterministic air quality models on the basis of reliable measurements. Low-cost air quality sensors are widely known for their increased spatial coverage and economic operational costs, but usually, their reliability is in dispute. In this study, a dense network of calibrated PM2.5 measurements installed in the city of Patras is combined with CAMS forecasts and statistical approaches to generate 24h forecasts of PM2.5 concentrations in an urban area of Greece. The implemented techniques are the analog ensemble (AnEn) and the Long Short-Term Memory (LSTM) network. Auxiliary variables of meteorological origin were also utilized. The required forecasts were retrieved from the European Center for Medium-Range Weather Forecasts (ECMWF), and were pin-pointed to the location of the air quality monitoring stations. The results showed that both methods had comparable performance, with low bias and relatively small errors. In the stations with high PM2.5 levels, AnEn performed better, whereas in the stations and seasons with moderate concentrations LSTM outperformed. A comprehensive validation is presented and discussed. AnEn and LSTM methods were proved reliable tools for air pollution forecasting and can be used for other regions with small modifications.