bluuebunny/crossref_metadata_2025 huggingface dataset:
Whistler waves observed by Solar Orbiter during its first orbit
Authors: Kretschmar Matthieu , Chust Thomas , Graham Daniel , Krasnosekskikh Volodya , Colomban Lucas , Maksimovic Milan , Horbury Timothy , Owen Christofer , Louarn Philippe
Published: March 2021

Plasma waves can play an important role in the evolution of the solar wind and the particle velocity distribution functions in particular. We analyzed the electromagnetic waves observed above a few Hz by the Radio Plasma Waves (RPW) instrument suite onboard Solar Orbiter, during its first orbit, which covered a distance from the Sun between 1 AU and 0.5 AU.  We identified the majority of the detected waves as whistler waves with frequency around  0.1 f_ce and right handed circular polarisation. We found these waves to be mostly aligned or anti aligned with the ambient magnetic field, and rarely oblique. We also present and discuss their direction of propagation and the variation of the waves' properties with heliocentric distance.
Offshore ground movements in the Campi Flegrei caldera during the last ~12 ka
Authors: Marino Camilla , Ferranti Luigi , Natale Jacopo , Sacchi Marco , Anzidei Marco
Published: March 2021

Appraisal of morphodepositional markers tied to ancient sea-levels in high-resolution seismic profiles together with geo-archaeological markers along the coast of the Pozzuoli Bay provided insights into the vertical deformation of the submerged part of the Campi Flegrei caldera (Southern Italy).

The collapse of the central part of the Campi Flegrei caldera is associated with the eruption of the Neapolitan Yellow Tuff (NYT) at ~15 ka. The NYT caldera collapse was followed by central dome resurgence associated with alternations of fast uplift and subsidence displacements that accompanied with discrete phases of intra-caldera volcanic activity. Previously, the evolution of ground movement in the Campi Flegrei caldera has been reconstructed using marine deposits uplifted onland or archaeological evidence and historical accounts and thus offers a mainly 2D appraisal of the deformation pattern. However, a complete reconstruction of post-collapse deformation suffers of the limitation that nearly two-thirds of the caldera are submerged beneath the Pozzuoli Bay.

We contribute to fill this gap by providing a reconstruction of offshore and coastal deformation through estimation of the vertical displacement of morphodepositional markers in high-resolution seismic reflection profiles and geoarchaeological markers directly surveyed at shallow depths. Our interpretation reveals the occurrence of different sediment stacking pattern whose provides evidence of rapid and oscillating ground movements. Whereas the offshore morphodepositional markers provide displacement information for the last ~12 ka, for the last ~2 ka our interpretation is supported by ancient Roman sea-level indicators. The multi-dataset analysis has allowed disentangling the signal related to the post-caldera dynamics from a broader deformation signal that affects this part of the extensional margin of the Apennines.

The integration of offshore data in the study of past episodes of ground deformation, by yielding a more complete picture of the ground motions associated to the post-collapse evolution of the Campi Flegrei caldera, bears a significant contribution for a 3D reconstruction of this high-risk resurgence caldera. Besides, the multidisciplinary approach presented here can be relevant for investigations of other calderas spanning the sea-land transition.
The Brewer-Dobson circulation in CMIP6
Authors: Calvo Natalia , Abalos Marta , Benito-Barca Samuel , Garny Hella , Hardiman Steven , Lin Pu
Published: March 2021

The Brewer-Dobson circulation (BDC) is a key feature of the stratosphere that models need to accurately represent in order to improve the representation of surface climate variability. For the first time, the Climate Model Intercomparison Project includes in its phase 6 (CMIP6) a set of diagnostics that allow for careful evaluation of the BDC. Here, the BDC is evaluated against observations and reanalyses using historical simulations. CMIP6 results confirm the well-known inconsistency in BDC trends between observations and models in the middle and upper stratosphere. The increasing CO2 simulations feature a robust acceleration of the BDC but also reveal large uncertainties in the deep branch trends. The very close connection between the shallow branch and surface temperature is highlighted, which is absent in the deep branch. The trends in mean age of air are shown to be more robust throughout the stratosphere than those in the residual circulation.
Land degradation in savanna environments - assessments, dynamics and implications
Authors: Baade Jussi , Le Roux Jay J. , Morgenthal Theunis , Nghiyalwa Hilma Sevelia
Published: March 2021

Land degradation is a human-induced process deteriorating ecosystem functioning and services including soil fertility or biological productivity and, usually, it is accompanied by a loss of biodiversity. Land degradation causes on-site and off-site damages like a profound change or removal of vegetation cover and soil erosion on one hand as well as flooding of receiving streams and siltation of reservoirs one the other hand. Thus, land degradation poses a threat to a number of Sustainable Development Goals (SDG) including foremost sustainable life on land and under water, the provision of clean water and eventually the eradication of poverty and hunger on Earth.

Often, land cover change is a valid indicator of land degradation providing the opportunity to take advantage of the increasing geometrically and temporally high-resolution remote sensing capabilities to identify and monitor land degradation. However, especially in semi-arid regions like savanna environments, globally driven inter-annual and decadal climate variations cause as well profound land cover dynamics which might be mistaken for land degradation.

Assessing and combating land degradation has already a long scientific, socio-economic and political history. Based on this, the aim of this session is to explore the wide range of methodological approaches to assess land degradation, its dynamics over all spatial and temporal scales as well as the implications for society and the interaction with the different spheres of the Earth including the anthroposphere, atmosphere, biosphere, hydrosphere and pedosphere. Contributions to this session can be based on field work, remote sensing approaches or modelling exercises, they can also focus on specific physical and socio-economic aspects of land degradation like land management, land cover change or soil erosion or discuss land degradation in a broader societal context. The aim of this contribution is to provide a concise overview of the thematic framework, current activities, research questions and advancements.
Metarbarcoding reveals distribution patterns of DNA in surface sediments of a large lake 
Authors: Wang Yi , Gutbrod Lisa , Schmid Myriam , Epp Laura
Published: March 2021

Lake sedimentary ancient DNA has become a recognized source of information on past biodiversity change, but our understanding of its distribution and taphonomy is still limited. Here we collected 40 surface sediment samples from Lake Constance in southern Germany and characterized sedimentary DNA (sedDNA) heterogeneity through four metabarcoding PCRs on general eukaryotes, vascular plants, cyanobacteria and copepods.  We observed the variability of overall sedDNA being strongly correlated with sediment sample geographical locations, although this pattern varies within taxonomic groups. Specifically, geographical coordination and water depth explain 10.7% variability of terrestrial vascular plant sedDNA distribution, but the distribution of copepods is patchy and not correlated with sampling locations. Out study indicates that sedDNA is not distributed uniformly across the lake but rather linked to the movement of lake water and the local presence of the organisms.
Relation among geochemical elements in soil and red chicory as a tool for geographical origin identification.
Authors: Marrocchino Elena , Di Sarcina Serena , Ragazzi Carlo , Vaccaro Carmela
Published: March 2021

The identification of the geographical origin of food products is important for both consumers and producers to ensure quality and avoid label falsifications. Determination and authentication of the geographical origin of food products throughout scientific research have become recently relevant in investigations against frauds for consumer protection. Advances in methods and analytical techniques led to an increase in the application of fingerprinting analysis of foods for identification of geographical origin. Since in organic material the inorganic component is more stable than the organic one, several studies examined trace elements, suggesting the potential application for determination of geographical origin. Moreover, the studies on territoriality are based on the hypothesis that chemical elements detected in plants and in their products reflect those contained in the soil and, within these studies, the geographical features of the production area, such as the soil type and the climate, are considered relevant factors affecting the specific designation, so an accurate determination of geographical origin would be necessary to guarantee the quality and territoriality of the products.

In this light, two varieties of red chicory from the southern Po Delta area have been characterized together with the soil. The two inspected red chicory varieties (long-leaves and round-leaves) are cultivated in a well-defined area in the southern part of Po Delta, in an area sited around Massenzatica (Municipality of Mesola, Province of Ferrara, NE of Italy). Sampling was undertaken between October and December 2020 and samples were collected from a randomized field. Together with the red chicory also roots and soils have been collected in order to analyze each part and correlate the geochemical data obtained using ICP-MS and XRF techniques.

Purpose of this study is to establish a method to identify the geographical origin and the results confirm that some major and trace elements could be used as geochemical markers according to the geological areas. These elements, therefore, could be useful to establish geochemical fingerprints for testing the origin of this product and create a protected designation of origin label.
An assessment of the likelihood of contrail formation 
Authors: Caria Giacomo , Dal Gesso Sara
Published: March 2021

Air Transport has for a long time been linked to environmental issues like pollution, noise and climate change. Aviation emissions, such as carbon dioxide (CO2), water vapour (H2O), nitrogen oxides (NOx), soot and sulphate aerosols, alter the concentration of atmospheric Greenhouse gases and trigger the formation of contrails and cirrus clouds. The ClimOP collaboration, an Horizon 2020 project, aims to identify, evaluate and support the implementation of mitigation strategies to initiate and foster operational improvements which reduce the climate impact of the aviation sector. To this end, we present a study that assesses the likelihood of contrail formation as a function of key atmospheric variables, at different altitudes.
The Last Glacial Maximum in northern Baffin Bay
Authors: Søby Özdemir Karen , Detlef Henrieka , Lambertucci Linda , Pearce Christof
Published: March 2021

Little is known about climate and ocean conditions during the Last Glacial Maximum in Baffin Bay, Greenland. This is partly due to the dissolution of biogenic carbonates in the central Baffin Bay, preventing reliable 14C-chronologies. We present the results from a transect of gravity cores retrieved during the 2019 BIOS cruise on the HDMS Lauge Koch in the northern Baffin Bay. Core LK19-ST8-14G has been analyzed for grain size variations, sea-ice biomarkers, XRF, and color spectrophotometry. A preliminary chronology based on radiocarbon dates from foraminifera show that the bottom of the core is approximately 35.000 cal. years BP while the top sediments are of Late Holocene age. The sediment archive thus covers the full extent of the LGM and the last deglaciation. High-resolution photography and CT scans allowed the identification of distinctly different lithofacies in the sediment archive. The lower sections of the core are characterized by laminated mud with no IRD and absence of microfossils indicating a sub ice-shelf environment during the glacial period. The laminated sequence is interrupted by several coarser, detrital-carbonate (DC) rich layers which are interpreted as episodes of glacial retreat or ice-shelf collapse. The youngest of these DC layers immediately precedes the Holocene, which is represented by approximately 40 cm of bioturbated sediments with some IRD. This interpretation is supported by the concentrations of HBIs and sterols throughout the core, which indicate near perennial ice cover in the glacial northern Baffin Bay and more open water conditions during the Holocene.
OCRE: started the funding opportunities for the European research community for using OCRE’s procured Cloud and Earth Observation commercial services.
Authors: Delgado Blasco José Manuel , Romeo Antonio , Heyns David , Antoniou Natassa , Carrillo Rob
Published: March 2021

The OCRE project, an H2020 funded by the European Commission, aims to increase the usage of Cloud and EO services by the European research community by putting available EC funds 9.5M euro, aiming to removing the barriers regarding the service discovery and providing services free-at-the-point-of-the-user.

OCRE started to grant EU research projects for using OCRE’s procured Cloud commodity and EO services through respective open calls in 2019-2020. Additionally, in 2021 additional open calls are foreseen also for projects willing to receive funds for using EO services procured by the OCRE project. Also, a permanent open call for individual researchers is foreseen.

During 2020, OCRE also funded, through another open call, EU projects dealing with research related to COVID-19 and they were the first projects that started the usage of the available commodity services. Additionally, in 2020, the OCRE project closed and awarded EU service providers for the provision of cloud and commodity services and, in early 2021, the Dynamic Purchasing System (DPS) for the procurement of EO services will be opened.

Additionally, during 2020 an External Advisory Board (EAB) was created to assist OCRE in the project awarding process. The EAB is formed by recognized experts from different domains providing OCRE with the balanced knowledge needed to ensure transparency and equality in such an important process.

This presentation will provide an overview of the possibilities offered by OCRE to researchers interested in boosting their activities using commercial cloud services.
New continuity-based velocity interpolation scheme for staggered grids
Authors: Gerya Taras , Duretz Thibault , Ludovic Rass
Published: March 2021

In the marker-in-cell method combined with staggered finite differences, Lagrangian markers carrying information on material properties are advected with the velocity field interpolated from the staggered Eulerian velocity grid. With existing schemes, velocity interpolation from the grid points to markers violates (to some extent) mass conservation requirement that causes excess convergence/divergence of markers and opening marker gaps after significant amount of advection. This effect is especially well visible in case of diagonal simple shear deformation along planes that are oriented at 45 degrees to the grid and marker circulation through grid corners.

Here, we present a new second order velocity interpolation scheme that guarantees exact interpolation of normal strain rate components from pressure nodes (i.e. from the locations where these components are defined by solving of the mass conservation equation). This new interpolation scheme is thus applicable to both compressible and incompressible flow and is trivially expendable to 3D and to non-regular staggered grids.

Performed tests show that, compared to other velocity interpolation approaches, the new scheme has superior performance in preserving continuity of the marker field during the long-term advection including the diagonal simple shear deformation and marker circulation through grid corners. We showcase a performance-oriented implementation of the new scheme using Julia language's shared memory parallelisation features. The Julia implementation of the new advection schemes further augments the ParallelStencil.jl  related application collection with advection routines.
Optimization strategies for efficient high-resolution volcanic plume simulations with OpenFOAM
Authors: Brogi Federico , Amati Giorgio , Boga Gabriele , Castellano Miguel , Gracia Jose , Esposti Ongaro Tomaso , Cerminara Matteo
Published: March 2021

In the last years, the interest in three-dimensional  physico-mathematical models for volcanic plumes has grown, motivated by the need of predicting accurately the dispersal patterns of volcanic ash in the atmosphere (to mitigate the risks for civil aviation and for the nearby inhabited regions) and pushed by improved remote sensing techniques and measurements. However, limitations due to the mesh resolution and numerical accuracy as well as the complexity entailed model formulations, have so far prevented a detailed study of turbulence in volcanic plumes at high resolution. Eruptive columns are indeed multiphase gas-particle turbulent flows, in which the largest (integral) scale is in the order of tens or hundreds of kilometers and the smallest scale is of the order of microns. Performing accurate numerical simulations of such phenomena remains therefore a challenging task.

Modern HPC resources and recent model developments enable the study of multiphase turbulent structures of volcanic plumes with an unprecedented level of detail. However, a number of issues of the present model implementation need to be addressed in order to efficiently use the computational resources of modern supercomputing machines. Here we present an overview of an optimization strategy that allows us to perform large parallel simulations of volcanic plumes using ASHEE, a numerical solver based on OpenFOAM and one of the target flagship codes of the project ChEESE (Centre of Excellence for Exascale in Solid Earth). Such optimizations include: mixed precision floating point operations to increase computational speed and reduce memory usage, optimal domain decomposition for better communication load balancing and asynchronous I/O to hide I/O costs. Scaling analysis and volcanic plume simulations are presented to demonstrate the improvement in both computational performances and computing capability.
Towards optimised seismic monitoring of hydraulic stimulations, the STIMTEC and STIMTEC-X experiments at Reiche Zeche Mine, Germany
Authors: Boese Carolin , Kwiatek Grzegorz , Dresen Georg , Renner Joerg , Fischer Thomas
Published: March 2021

The STIMTEC and STIMTEC-X hydraulic stimulation experiments are designed to investigate hydro-mechanical processes controlling the enhancement of hydraulic properties in deep geothermal projects. We combine periodic pumping tests, high-resolution seismic monitoring, structural analysis and mine-back drilling into stimulated volumes in an effort to improve near-real-time monitoring, phenomenological models of the hydrofrac/hydroshear process, and prognosis strategies. The ongoing experiments are located at the Reiche Zeche underground laboratory in Freiberg, Saxony/Germany, at a depth of about 130 m below surface in strongly foliated metamorphic gneisses.

The most recent field campaign and initial phase of STIMTEC-X in October 2020 involved eleven local stress measurements in three existing boreholes, previously used for monitoring purposes, with varying orientations and lengths. We hydraulically tested nine previously stimulated intervals and performed eight dilatometer tests in previously stimulated and new intervals to determine deformation characteristics of induced hydrofracs and pre-existing fractures. We monitored these operations in real-time using an adaptive, high-resolution seismic monitoring network comprising six acoustic emission (AE)-type hydrophones, six regular AE sensors and four accelerometers. Hydrophones were never installed before in combination with hydraulic gauges or the double packer probe used for localized injection as during STIMTEC-X. Hydrophones were optimally placed for each measurement configuration anew with at least one deployed in the direct vicinity (~3-4 m) of the injection interval to make best use of the existing infrastructure. This led to an improvement in detection and localisation of induced AE events. A series of active seismic measurements allowed us to establish the polarization, amplitude sensitivity, detection ranges, resonance frequencies and suitability to detect S-waves of the hydrophones. Good signal to noise ratios were recorded for distances up to 17 m. The range of incidence angles, including incidence angles from the opposite direction, in which the sensor is facing, was obtained that can be used for magnitude determination.

A circulation experiment between the injection borehole and two newly drilled boreholes of 23 m and 30 m depth as part of STIMTEC-X is anticipated for March 2021. Here, we present lessons learned from seismic monitoring the STIMTEC and STIMTEC-X hydraulic stimulation campaigns and highlight the advantages of using adaptive and flexible networks. We present an overview of the STIMTEC-X experiment and first results addressing the heterogeneity in stress and deformational behaviour seen throughout the anisotropic reservoir.
New Earth-space infrastructures enable full-scale monitoring capability
Authors: Tanskanen Eija , Raita Tero , Tammi Joni , Pulliainen Jouni , Koivula Hannu , Ulich Thomas , Hynönen Reko , Kukkonen Ilmo , Korja Annakaisa
Published: March 2021

The near-Earth environment is continuously changing by disturbances from external and internal sources. A combined research ecosystem is needed to be able to monitor short- and long-term changes and mitigate their societal effects. Observatories and large-scale infrastructures are the best way to guarantee continuous 24/7 observations and full-scale monitoring capability. Sodankylä Geophysical Observatory takes care of continuous geoenvironmental monitoring in Finland and together with national infrastructures such as FIN-EPOS and E2S enable extending and expanding the monitoring capability. European Plate Observing System of Finland (FIN-EPOS) and flexible instrument network of FIN-EPOS (FLEX-EPOS) will create a national pool of instruments including geophysical instruments targeted for solving topical questions of solid Earth physics. Scientific and new hardware building by FLEX-EPOS is essential in order to identify and reduce the impact of seismic, magnetic and geodetic hazards and understand the underlying processes.

 

New national infrastructure Earth-Space Research Ecosystem (E2S) will combine measurements from atmosphere to near-Earth and distant space. This combined infrastructure will enable resolving how the Arctic environment change over the seasons, years, decades and centuries. We target our joint efforts to improve the situational awareness in the near-Earth and space environments, and in the Arctic for enhancing safety on ground and in space. This presentation will give details on the large-scale Earth-space infrastructures and research ecosystems and will give examples on how they can improve the safety of society.
Seismic Hazard Assessment for the Energy Facilities in Marmara Region
Authors: Zulfikar Abdullah Can , Okuyan Akcan Seyhan
Published: March 2021

Marmara region is a tectonically active part of Turkey. Over the history, the Marmara region has been the site of numerous destructive earthquakes such as the 1509 Istanbul earthquake (Mw=7.5), 1766 Istanbul earthquake (Mw=5.63), 1953 Yenice-Gönen Depremi (Ms=7.2), 1999 Kocaeli (Mw=7.4) and Düzce (Mw=7.2) earthquakes. Many Electric power systems located in the Marmara region are exposed to the destructive effects of potential earthquakes. The serviceability and functionality of the electric power systems after a major earthquake are major concerns for people's wealth. Thus, the design of the electric power system requires site-specific seismic hazard assessment. Site-specific hazard analysis provides a uniform hazard spectrum used for the design of power structures. Response spectrums are presented for the seismically resistant design of the structures according to the Turkey Building Earthquake Regulation 2018 (TBDY2018) and Turkish Seismic Code 2007 (TSC2007) regulations. 
In this study, seismic hazard assessment of the Marmara region has been studied using the Openquake platform. Earthquake hazard has been investigated using the time-independent probabilistic (Poisson) models. Probabilistic seismic hazard assessment (PSHA) is conducted based on SHARE project ESHM13 model characteristics. The SHARE project has presented the 2013 European –Mediterranean seismic hazard model (ESHM13). ESHM13  models consist of all events with magnitudes Mw>=4.5 in the computation of seismic hazard and it covers the whole European territory including Turkey. The probabilistic seismic hazard assessment calculations take into account SHARE seismic source characterization. Akkar&Bommer(2010), Cauzzi&Faccioli(2008), Chiou&Youngs(2008), and Zhao et.al (2006) ground motion prediction models have been considered for active shallow crustal tectonic region. The study has developed uniform hazard spectrum and hazard maps of the Marmara Region with peak ground acceleration (PGA) and spectral accelerations (SA)’s at 0.2s and 1s periods corresponding to 10% and 2% probabilities of exceedance in 50 years. Obtained uniform hazard spectrums of electric power systems in the Marmara region have been compared with response spectrums of TBDY2018 and TSC-2007. The compatibility of SHARE model hazard analysis results with TBDY 2018 and TSC2007 has been assessed.
Variable Antarctic ice flux linked to ocean forcing, bed topography and ice shelf buttressing
Authors: Miles Bertie , Stokes Chris , Jamieson Stewart , Jordan Jim , Gudmundsson Hilmar , Jenkins Adrian
Published: March 2021

It has been widely reported that ice flux from the Antarctic Ice Sheet has increased over the preceding decades. The vast majority of these increases can be attributed to the ongoing destabilization of the Amundsen Sea sector in West Antarctica, with a much more limited change in East Antarctica. However, much less attention has been focussed on the temporal and spatial variations of ice flux in Antarctica over the observational period.

In this study we combine existing velocity products (ITS_LIVE and MEaSUREs) to create 12 timestamped velocity mosaics between 1999 and 2018 to investigate both overall trends in ice flux and the temporal and spatial variability across our observational period. At an ice sheet scale we report a 45 GT yr-1 increase in ice discharge in West Antarctica and no overall change in East Antarctica. However, at an individual catchment scale we observe considerable temporal and spatial variability. For West Antarctica, despite the overall increase in discharge clear periods of deceleration are observed in most individual catchments. In East Antarctica, despite overall consistency, 3-10% variations in ice discharge are observed at several major outlet glaciers (e.g. Denman, Totten, Frost, Cook, Matusevitch, Rennick). These variations can be linked to regional oceanic variability along with highly localised differences in bed topography and ice shelf calving. In some cases, this can result in neighbouring catchments simultaneously undergoing opposing trends. Improving our understanding the processes driving these short-term variations will be important in improving the accuracy of future sea level contributions from Antarctica.
Groundwater dynamics in the Betwa River catchment in Central India
Authors: Naik Niranjan , Beg Zafar , Kumar Amit , Gaurav Kumar
Published: March 2021

Groundwater is an important natural freshwater resource and plays a significant role in the socio-economic development of any country. The Betwa River basin in central India has experienced severe exploitation of groundwater resource in the past few decades. About 80 % of groundwater in this region is extracted for the agriculture purpose. Also, the scarcity in rainfall throughout the year and seasonal flow in the Betwa River has increased the agricultural dependence on the groundwater. This has led the Betwa River basin into a major hot spot of groundwater depletion.

This study estimates the trend of groundwater level and storage change to assess the groundwater dynamics in the Betwa River basin. We used in-situ groundwater level data for a period between 1987-2018 to calculate the trend in groundwater level using the Seasonal and Trend decomposition using Loess (STL) method. Further, we performed the Ordinary Kriging to understand the spatial and temporal trends of groundwater during the pre-monsoon and post-monsoon. Eventually, we use the water table fluctuation (WTF) method to estimate groundwater storage in the study area. Our results suggest a decline in groundwater storage change as 701 and 626 MCM in the post and pre-monsoon period respectively from 2008-2018. During the same period, we observed that the Betwa basin has experienced about 3-5 m decline in the groundwater level.

 
Wildfire impacts on soil hydrological properties and erosion in stony and shallow soils of a forested Mediterranean catchment in Italy
Authors: Mastrolonardo Giovanni , Castelli Giulio , Certini Giacomo , Maxwald Melanie , Trucchi Paolo , Foderi Cristiano , Errico Alessandro , Marra Elena , Preti Federico
Published: March 2021

Wildfires can affect agroforest-ecosystems generating several cascade effects on the soil-water continuum, among which erosion is one of the most important. Even so, few field studies analyse post-fire soil erosion at watershed scale, especially in the Mediterranean Basin, although here wildfires are particularly frequent.

The present work analyses the impact of the first rain events following one severe wildfire in the Pisan Mountains, Tuscany region, Italy, with the aim to quantify and characterize the post-fire impact in terms of soil erosion and sediment yield at watershed scale.

The study site is characterized by olive groves, maquis, maritime pine and chestnut forest, depending on the elevation. The area was affected by a fire involving an area of about 1000 ha in September 2018. Fire severity was assessed by remote sensing imagery, while fire impact on soil properties and sediment yield was assessed by field experiments, and sampling and lab analysis. Finally, a hydrological model was implemented in HEC-HMS environment for exploring the relationship between the erosion-deposition events monitored in a sample watershed, and the hydrological processes induced by the rainfall events.

Experimental analysis revealed that the organic fraction of topsoil dramatically declined after the wildfire, together with the saturated hydraulic conductivity. Fire occurrence also generated a shift in the soil water repellency. The analysis of sediment deposited at the outlet of the catchment revealed that the first two rainfall-induced erosion-deposition events transported a larger amount of non-organic sediments, probably already close to the riverbed before the fire, while the other four events analyzed corresponded to deposited material much richer in organic matter, produced by the fire event. Overall, at watershed scale, soil erosion amounted to 7.85 t/ha, a relatively moderate rate considering the large fire impact on soil. This could be partly explained by the shallow soil depth of the study area (around 50 cm on average) and the high stoniness of soil, which would lead to preferential infiltration pathways for water, reducing runoff and erosion.
Why sometimes its simply sunny (in the trades)
Authors: Stevens Bjorn , Serikov Ilya , Albright Anna Lea , Bony Sandrine , George Geet , Hirsch Lutz , Jansen Friedhelm , Kölling Tobias , Schulz Hauke , Vogel Raphaela , Worbes Ludwig
Published: March 2021

Cloud free skies are rare in the trades.  We analyze conditions in which cloud-free conditions prevail.  For this purpose Raman water vapor measurements from the Barbados Cloud Observatory, complemented by ship-based measurements during EUREC4A are used to explore water vapor variability in the marine boundary layer.   We explore the consistency of the inferred cloud base height with estimates of temperature and water vapor from the lidar signal, and examine the co-variability of these quantities.  After having established the properties of these measurements, we seek to use them as well as others, to explain in what ways periods of cloud-free conditions are maintained, investigating the hypothesis that only when the wind stills is it simply sunny.
Quantification of Yield, Water, and Carbon budget at intra-field scale using the AgriCarbon-EO tool
Authors: Al Bitar Ahmad , Wijmer Taeken , Arnaud Ludovic , Fieuzal Remy , Pique Gaetan , Ceschia Eric
Published: March 2021

Achieving the United Nations Sustainable Development Goal 2 that addresses food security and sustainable agriculture requires the promotion of readily transferable and scalable agronomical solutions. The combination of high-resolution remote sensing data, field information, and physical models is identified as a robust way of answering this requirement.  Here, we present the AgriCarbon-EO tool, a decision support system that provides the yield, biomass, water and carbon budget components of agricultural fields at a 10m resolution and at a regional scale. The tool assimilates high resolution optical remote sensing data from Copernicus Sentinel-2 satellites into a  radiative transfer model and a crop model. First, the application of a spatial Bayesian retrieval approach to the PROSAIL radiative transfer model provides Leaf Area Index (LAI) with its associated uncertainty. Second, LAI is assimilated into the SAFYE-CO2 crop model using a temporal Bayesian retrieval that enables the calculation of the yield, biomass, carbon and water budgets components with their associated uncertainties. In addition to remote sensing data, input datasets of crop types, weather and soil data are used to constrain the system. The concise weather data is provided from local weather stations or weather forecasts and is used to force the crop model (SAFYE-CO2) dynamics. The soil data are used in two folds. First to better parametrize the soil emissions in the radiative model retrievals and second to parametrise the water infiltration in the soil module of the crop model. The AgriCarbon-EO tool has been optimized to enable the computation of the yield, carbon, and water budget at high spatial resolution (10m) and large scale (100km2). The model is applied over the South-West of France covered by 3 Sentinel-2 tiles for major crops (wheat, maize,  sunflower). The outputs are validated over experimental plots for biomass, yield, soil moisture, and CO2 fluxes located all in the South-West of France. The experimental sites include the FR-AUR and FR-LAM ICOS sites and 22 cropland fields (biomass sampling). The validation exercise is done for the 2017-2018 and 2019-2020 cultural years. We show the added value of the use of high resolution in driving the crop model to take into account the impact of complex processes that are embedded in the LAI signal like vegetation water stress, disease, and agricultural practices. We show that the system is capable of providing the yield, carbon, and water budget of major crops accurately.  At the regional scale, we give global estimates of the carbon budget, water needs, and yields per crop type. We present the impact of intra-plot heterogeneity in the estimation of yield and the annual carbon and water budget showing the added value for high-resolution intra-plot modeling.
Aircraft mass balance estimate of methane emissions from offshore gas facilities in the Southern North Sea
Authors: Pühl Magdalena , Roiger Anke , Fiehn Alina , Schwietzke Stefan , Allen Grant , Foulds Amy , Lee James , France James L. , Lachlan-Cope Tom , Warwick Nicola , Pisso Ignacio
Published: March 2021

Atmospheric methane (CH4) concentrations have more than doubled since the beginning of the industrial era, making methane the second most important anthropogenic greenhouse gas after carbon dioxide (CO2). Fossil fuel extraction is one of the major anthropogenic methane sources as it is estimated to account for 22 % of global CH4 emissions. However, studies indicate that inventories underestimate emissions arising from the oil and gas industry.

In two airborne field campaigns carried out in spring 2018 and 2019 offshore gas facilities in the Southern North Sea were probed. A total of nine research flights were conducted to characterize platform emissions. The Twin Otter research aircraft, operated by the British Antarctic Survey, was equipped with a high-precision 10 Hz analyzer (Picarro) to continuously measure CH4 and CO2. In order to identify fossil fuel emissions ethane (C2H6) was simultaneously measured with a 1 Hz TILDAS instrument (Aerodyne Research, Inc). On offshore oil and gas platforms methane is emitted by leakage, venting or flaring. To catch the methane plume, stacked transects were flown downwind of single platforms or platform complexes.

Methane fluxes were calculated for six British and four Dutch facilities using the mass balance method. Correlations with C2H6 and CO2 were found with the latter indicating partly combusted methane from flaring. Uncertainties of fluxes arise mainly due to uncertainty of the wind measurement and the plume height. The calculated fluxes were compared to emissions reported to inventories (UK National Atmospheric Emissions Inventory (NAEI), UK Environmental and Emissions Monitoring System database (EEMS), Scarpelli inventory (2016)) and individually reported emissions from Dutch operators.
Distributed urban drag parameterization in the sub-kilometre scale London Model
Authors: Sützl Birgit , Rooney Gabriel , Finnenkoetter Anke , Bohnenstengel Sylvia , Grimmond Sue , van Reeuwijk Maarten
Published: March 2021

Urban environments in numerical weather prediction models are currently parameterised as part of the atmosphere-surface exchange at ground-level. The vertical structure of buildings is represented by the average height, which does not account for heterogeneous building forms at the subgrid-level. The use of city-scale models with sub-kilometre resolutions and growing number of high-rise buildings in cities call for a better vertical representation of urban environments.

We present the use of a newly developed, height-distributed urban drag parameterization with the London Model, a high-resolution version of the Met Office Unified Model over Greater London and surroundings at approximately 333 m resolution. The distributed drag parameterization requires vertical morphology profiles in form of height-distributed frontal area functions, which capture the full extent and variability of building-heights. These morphology profiles were calculated for Greater London and parameterised by an exponential distribution with the ratio of maximum to mean building-height as parameter.

A case study with the high-resolution London Model and the new drag parameterization appears to capture more realistic features of the urban boundary layer compared to the standard parameterization. The simulation showed increased horizontal spatial variability in total surface stress, identifying a broad range of morphology features (densely built-up areas, high-rise building clusters, parks and the river). Vertical effects include heterogeneous wind profiles, extended building wakes, and indicate the formation of internal boundary layers. This study demonstrates the potential of height-distributed urban parameterizations to improve urban weather forecasting, albeit research into distribution of heat- and moisture-exchange is necessary for a fully distributed parameterization of urban areas.
Compound disaster scenarios for risk management assessment in CAREC countries
Authors: Willis Iain , Cheong Amanda , Au Christopher , Rao Anirudh , Millinship Ian
Published: March 2021

A compound disaster defines a situation with adverse consequences resulting from different, but related, disaster‐agents (ICLA 1996). These low probability extreme events can correspond to events with multiple concurrent or consecutive drivers, resulting in major financial or physical loss (Sadegh et al., 2018). In this study, disaster scenarios involving natural hazards and pandemics were developed to assess the risk and implications of a compound event to member countries of the Central Asia Regional Economic Cooperation (CAREC) area.

A partnership of 11 countries (Afghanistan, Azerbaijan, China (Inner Mongolia Autonomous Region; Xinjiang Uyghur Autonomous Region), Georgia, Kazakhstan, Kyrgyz Republic, Mongolia, Pakistan, Tajikistan, Turkmenistan and Uzbekistan) across Asia, the CAREC countries work together to promote sustainable development, economic growth and reduce poverty. High exposure to flooding and earthquake coupled with low insurance penetration means natural catastrophes are significantly material to the public sector balance sheet. This collaborative study involving multiple hazard modelling agencies assesses the potential impact of natural perils concurrent to pandemic/epidemic outbreaks.

The compound events developed represent Realistic Disaster Scenarios (RDS) for the specific areas they represent and are based on plausible low-probability, high-consequence events such as the 2015 floods in Tbilisi and the 1905 Bolnai earthquake in Mongolia. The impact of the natural events is then further compounded by modelled infectious disease outbreaks for each given scenario.

High resolution fluvial and pluvial flood hazard scenario footprints (30m x 30m), earthquake hazard intensity maps and gridded population data (Worldpop) are modelled alongside outbreaks including respiratory (including flu), Nipah and Crimean-Congo haemorrhagic fever, to assess the compounded impact. The humanitarian and financial loss potential of these events are then presented in the context of alternative disaster risk financing measures and adaptation strategies aimed at increased resilience.

 

ICLA (1996), International Conference on Local Authorities Confronting Disasters and Emergencies, Background Documents, Amsterdam.

Sadegh, M., Moftakhari, H., Gupta, H. V., Ragno, E., Mazdiyasni, O., Sanders, B., ... & AghaKouchak, A. (2018). Multihazard scenarios for analysis of compound extreme events. Geophysical Research Letters, 45(11), 5470-5480.
Reconstruction of Dynamically Evolving Volcanic Ash Clouds from Simulated Satellite Imagery
Authors: Etchells Tom , Berthoud Lucy , Wood Kieran , Calway Andrew , Watson Matt
Published: March 2021

Large volcanic eruptions can pose significant hazards over a range of domains. One such hazard is volcanic ash becoming suspended in the atmosphere. This can lead to significant risks to aviation, with the potential to cause severe or critical damage to jet engines. As such, the effective measurement and forecasting of ash contaminated airspace is of vital importance. Forecasts are generally produced using volcanic ash atmospheric transportation and dispersion models (ATDMs). Among the inputs to these models are eruption source parameters such as cloud-top height and cloud volume. One method of providing estimates of these source parameters, and to aid in characterising the size, shape, and distribution of a volcanic plume, is the reconstruction of the outer hull of the plume using multi-angle imagery.

When considering platforms for generating this imagery, satellites provide a range of advantages. These include the potential for global coverage, the wide range of viewing angles during an orbital pass, and being safely removed from any potential volcanic hazards. This method of plume reconstruction has been previously demonstrated by the authors using simulated satellite imagery of a model volcanic plume. However, the simple model plume used during this previous work was static and did not evolve with time, an assumption that is not realistic.

This presentation builds on the previous work and assess the efficacy of satellite imagery-based plume reconstruction under conditions closer to real-world, namely with a plume that is evolving with time. The time evolving plume model is produced via a Blender particle simulation. The images required for reconstruction are then generated at multiple user-determined time intervals and locations. A Space Carving reconstruction method is then applied to the imagery to generate the reconstructed plume. Performance and reconstruction accuracies are investigated by comparison of the reconstructed plume with the ‘ground-truth’ simulation model. The impacts of a range of variables on the reconstruction performance are investigated, including plume size, imager properties, satellite orbit, and the use of additional satellites. The accuracy of the Blender plume simulation is compared with more mature plume simulations such as the University of Bristol PlumeRise model. These comparison models were not themselves used for the reconstruction process due to issues with the generation of accurate imagery.

The improved simulation environment presented in this work further demonstrates the efficacy of a satellite-based reconstruction process for the measurement and forecasting of volcanic ash, potentially leading to improvements in hazard monitoring and aviation safety.
Model comparison of volcanic aerosol forcing and climate impact of tropical and extratropical eruptions
Authors: Zhuo Zhihong , Fuglestvedt Herman , Toohey Matthew , Mills Michael J. , Krüger Kirstin
Published: March 2021

Major volcanic eruptions increase sulfate aerosols in the stratosphere. This causes a large-scale dimming effect with significant surface cooling and stratosphere warming. However, the climate impact differs for tropical and extratropical eruptions, and depends on the eruption season and height, and volcanic volatiles injections. In order to study different volcanic aerosol forcing and their climate impact, we perform simulations based on the fully coupled Community Earth System Model version 2 (CESM2) with the version 6 of the Whole Atmosphere Community Climate Model (WACCM6) with prognostic stratospheric aerosol and chemistry. In this study, explosive eruptions at 14.6 N and 63.6 N in January and July injecting 17 MT and 200 MT SO2 at 24 km with and without halogens are simulated, in line with Central American Volcanic Arc and Icelandic volcanic eruptions. Simulated changes in the stratospheric sulfate and halogen burdens, and related impacts on aerosol optical depth, radiation, ozone and surface climate are analyzed. These simulated volcanic eruption cases will be compared with simulations based on the aerosol-climate model MAECHAM5-HAM.