bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulating Interactive Ice Sheets in the Multi-Resolution AWI-ESM: A case study using the SCOPE Coupler
Authors: Gierz Paul , Ackermann Lars , Rodehacke Christian , Krebs-Kanzow Uta , Stepanek Christian , Barbi Dirk , Lohmann Gerrit
Published: March 2021

Interactions between the climate and the cryosphere have the potential to induce strong non-linear transitions in the Earth's climate. These interactions influence both the atmospheric circulation, by changing the ice sheet's geometry, as well as the oceanic circulation, by modification of the water mass properties. Furthermore, the waxing and waning of large continental ice sheets influences the global albedo, altering the energy balance of the Earth System and inducing climate-ice sheet feedbacks on a global scale as evident in Pleistocene glacial-interglacial cycles. To date, few fully
comprehensive models exist, that do not only contain a coupled atmosphere/land/ocean component, but also consider interactive cryosphere physics. Yet, on glacial-interglacial and tectonic time scales, as well as in the Anthropocene, ice sheets are not in equilibrium with the climate, and prescribed fixed ice sheet representations in the model can principally be only an approximation to reality. Only climate models, that contain interactive ice sheets, can produce simulations of the Earth's climate which include all feedbacks and processes related to atmosphere-land-ocean-ice interactions. Previous fully coupled models were limited either by low spatial resolution or an incomplete representation of ice sheet processes, such as iceberg calving, surface ablation processes, and ocean/ice-shelf interactions. Here, we present the newly developed AWI-Earth System Model (AWI-ESM), which tackles some of these problems. Our modelling toolbox is based on the AWI-climate model, including atmosphere and vegetation components suitable for paleoclimate studies, a multi-resolution global ocean component which can be refined to simulate regions of interest at high resolution, and an ice sheet component suitable for simulating both ice sheet and ice shelf dynamics and thermodynamics. We describe the currently implemented coupling between these components, present first results for the Mid-Holocene and Last Interglacial, and introduce further ideas for scientific applications for both future and past climate states with a focus on the Northern Hemisphere. Finally, we provide an outlook on the potential of such fully coupled Earth System models in improving representation of climate-ice sheet feedbacks in future paleoclimate studies with this model.
Quantifying fluvial carbon losses from lowland peatland ecosystems across a drainage-impact spectrum 
Authors: Cox Peter , Gill Laurence , Regan Shane , Saunders Matthew
Published: March 2021

The export of Dissolved Organic Carbon (DOC) and evasion of carbon dioxide (CO2) from inland waters is increasingly being recognized as a key part of the terrestrial carbon (C) cycle, with recent global estimates suggesting that the magnitude of the aquatic CO2 conduit is equivalent to global Net Ecosystem Productivity (2.0 Gt C yr-1; Tranvik et al., 2009). However, a major weakness in the carbon balance estimation of terrestrial ecosystems, such as peatlands, is the poor quantification of DOC and CO2 evasion fluxes associated with drainage waters. This has implications for conservation, land-use management and climate change mitigation. Whilst intact peatland systems typically sequester carbon, drainage reverts peatlands to being C sources due, primarily, to the degradation of organic peat soil. This study examines the export of C in fluvial pathways from relatively intact catchments to those that are heavily drained, and also from peatland sites undergoing restoration works. This research is being carried out parallel other linked studies that are quantifying the carbon gaseous emissions from directly from the different bogs in order to determine the comparative net carbon budgets.

This study will focus on three raised bog sites in the midlands of Ireland: one in near natural condition (Clara bog), one significantly drained and degraded due to peat extraction (Garryduff) and one undergoing rehabilitation following many years of peat extraction (Cavemount). Flumes and sondes, with fluorescent dissolved organic matter (fDOM), temperature/conductivity and turbidity sensors, have been installed on the sites. The fDOM measurements will be correlated to grab samples taken every two weeks to give half hour proxy measurements for DOC.

Preliminary results suggest that DOC flux from the heavily drained and mined peatland site is some 295 times higher than that from the catchment with minimal interference. In addition to this, drainage waters are super-saturated in CO2 and rapidly evades back to the atmosphere resulting in an additional C loss. Thus, C losses in the drainage systems of peatland catchment areas are significantly under-reported and a significant source of C in countries with significant peat land cover such as Ireland. This research is thereby addressing the magnitude of C losses in fluvial pathways, the associated effects on ecosystem biodiversity and the effectiveness of restoration activities on mitigating against net C loss in degraded systems.
AQUACOSM-plus: an International Network for Aquatic Mesocosm Facilities Supporting Experimental Ecosystem Studies and cross-disciplinary RI- RI collaborations
Authors: Nejstgaard Jens C , Berger Stella A , Makower Katharina , Ptacnik Robert , Stibor Herwig , Magiopoulos Iordanis
Published: March 2021

To understand underlying mechanisms of aquatic ecosystem functioning in relating to the global Grand Challenges (climate change, biodiversity loss, eutrophication, emerging pollutants, etc.), it is necessary to consider processes in adjacent systems, such as atmosphere and adjacent aquatic and terrestrial systems. For freshwater and coastal systems, the aquatic-terrestrial coupling on the watershed level is specifically important. We argue that for a better understanding of both aquatic and terrestrial ecosystems a combination of long-term data from connected environments, coupled with experimental ecosystem-scale experiments, have a greater potential for successful model testing and development of predictive concepts, than using only long-term data (without experiments) from separate systems. This talk will present the EU-funded RI-project AQUACOSM-plus (www.aquacosm.eu, 2020-2024) that offers access to >60 research facilities across the EU and is linked to world-wide cooperation through the MESOCOSM.EU portal, a virtual network of >100 research facilities. These networks comprise mesocosm facilities in all aquatic systems, including rivers, ponds, lakes, estuaries and marine systems – offering unique opportunities to conduct ecosystem-scale experimental studies of relevance to aquatic-terrestrial coupling. These facilities allow for process studies to test models based on trend or response observations from long-term-data, in order to better understand underlying mechanisms of ecosystem responses to the present global Grand Challenges. The AQUACOSM-plus mesocosm facilities, are also open for conducting ecosystem solution-based experiments to enable effective management in aquatic ecosystems. The AQUACOSM network will open calls to fund access to >13.000 days for a wide range of external users. We will also present examples of developing RI-RI collaborations and development of technological solutions and instrumentation to enhance the mobility of mesocosms and increase opportunities for relevant scenario-testing by the scientific community at large.
Mapping present-day mountain treeline pattern based on high-resolution remote sensing images
Authors: He Xinyue , Zeng Zhenzhong , Spracklen Dominick , Holden Joseph , Ziegler Alan D.
Published: March 2021

Mountain forests, widely distributed around the world, are hotspots of biodiversity and provide important environmental services by conserving water and soil, regulating river flow and storing carbon. The upper altitudinal limits of trees is defined as the treeline. Some field investigations indicate that treelines around the world are moving upward as a response to global climate change. However, to date, a high-resolution spatial map of global mountain treeline position is still lacking. In this study, we develop an algorithm to detect the present-day tree line positions in mountain regions globally, via integrating a high-resolution tree distribution dataset with a high-resolution digital elevation model. The results are validated with even finer resolution remote sensing images in Google Earth. We analyse a range of climate datasets to understand important climate drivers of the present-day tree line position. Further, we explore the change in Normalized Difference Vegetation Index (NDVI) within the buffer zone of the treeline to determine how the treeline position has shifted in the last three decades. By providing the first global mountain treeline distribution, our analysis will help to reveal how mountain forests are responding to climate change globally, and to detect how the responses vary regionally.
Geomorphology, hydrology, and chronology of Early Holocene jökulhlaups along the Hvítá River and Gullfoss waterfall, Iceland
Authors: Wells Greta , Luzzadder-Beach Sheryl , Beach Timothy , Saemundsson Thorsteinn , Dugmore Andrew
Published: March 2021

Glacial outburst floods (jökulhlaups) have occurred across Earth throughout the Quaternary, often leaving a geomorphologic, sedimentological, and climatic legacy that extends far beyond the source region and can persist for millennia. Furthermore, they pose an increasing geohazard in glaciated landscapes worldwide due to climate-driven ice retreat. Iceland experiences more frequent jökulhlaups than nearly anywhere on Earth, though most research focuses on floods triggered by subglacial volcanic and geothermal activity. However, abundant evidence also exists for non-volcanogenic floods from proglacial lakes, which may serve as a better analogue for most global jökulhlaups.

As the Icelandic Ice Sheet retreated across Iceland in the Late Pleistocene-Early Holocene, meltwater lakes formed at ice margins and periodically drained in jökulhlaups. Some of the most catastrophic floods drained from ice-dammed Glacial Lake Kjölur, surging across southwestern Iceland from the interior highlands to the Atlantic Ocean. These floods left extensive geomorphologic evidence along the modern-day course of the Hvítá River, including canyon systems, scoured bedrock, boulder deposits, and Gullfoss—Iceland’s most famous waterfall. The largest events reached an estimated peak discharge on the order of 105 m3 s-1, ranking them among the largest known floods in Iceland and on Earth. Yet, all our evidence for the Kjölur jökulhlaups comes from only one publication from a quarter-century ago.

This project employs a combination of field, modelling, and laboratory methods to better constrain flood timing and dynamics at this underexplored site. This talk synthesizes geomorphologic field mapping, HEC-RAS hydraulic simulations and paleohydraulic calculations, and cosmogenic nuclide exposure dates to reconstruct Kjölur jökulhlaup routing, hydrology, and chronology. It situates these events within the context of Pleistocene-Holocene Icelandic Ice Sheet retreat and paleoenvironmental change, presenting a series of scenarios of ice margin position, glacial lake extent, and jökulhlaup drainage. Finally, it assesses the Kjölur jökulhlaups as an analogue to contemporary glacial outburst floods in other Arctic and alpine regions in terms of flood frequency, dynamics, and landscape impact.
Spatiotemporal ICA/PCA decomposition of optical displacement field stacks: perspective for landslide time series inversion
Authors: Provost Floriane , Malet Jean-Philippe
Published: March 2021

Monitoring ground surface motion is a key information to locate active landslides and possibly detect failure onsets but also to better understand their mechanical behavior in relation with environmental forcing. In-situ and remote technologies are available to provide measures of the ground displacement with different advantages and limitations (in terms of spatial coverage, sampling frequency, etc.). Image matching techniques have been commonly used to detect and measure landslide acceleration but this is often limited to a small amount of images. In the recent years, the number of optical satellite constellations have significantly increased providing global coverage with a frequent revisit time at medium to high spatial resolution and an open access policy (e.g. Sentinel 2, Landsat 7/8). These datasets present new perspectives for the monitoring of slow (cm/day) to moderate (m/month) landslide motion and poses challenges to discriminate between the different spatio-temporal sources (e.g. rainfall correlated signal, noise, seasonal signal, etc.) present in the time -series. 

We investigate the use of spatiotemporal ICA/PCA decomposition on optical displacement stacks of landslide areas. The main goal aims at testing 1) the capability of ICA/PCA analysis to detect relevant deformation deformation sources in the case of landslide monitoring and 2) the possibility to improve the time-series inversion of landslide motion by removing spatiotemporal sources that can result from seasonal sun exposition or geometric inaccuracies. We use the MPIC-OPT-Slide service of the GeoHazards Exploitation Platform (GEP) to compute several correlograms and displacement fields (>500 per site) from Sentinel-2 acquisitions on the slow-moving La Valette landslide (Alpes-de-Haute-Provence, France) and the moderately-moving Aiguilles-Pas de l’Ours landslide (Hautes-Alpes, France). We show that in case of steady-state deformation, the noise can be significantly removed around the active parts of the slope. In the case of more complex deformation evolution, pertinent sources can be manually isolated but the choice of the number of sources and their automatic selection remain challenging. 
A Standards-based Data Catalogue integrating scientific, community-based and citizen science data across the Arctic
Authors: Hamre Torill , Danielsen Finn , Køie Poulsen Michael , Monsen Frode
Published: March 2021

INTAROS is a Horizon 2020 research and innovation project developing an integrated Arctic Observation System by extending, improving, and unifying existing systems in the different regions of the Arctic. INTAROS integrates distributed repositories hosting data from ocean, atmosphere, cryosphere and land, including scientific, community-based monitoring (CBM) and citizen science (CS) data. Throughout the project, INTAROS has been working closely with several local communities and citizen science programs across the Arctic, to develop strategies and methods for ingestion of data into repositories enabling the communities to maintain and share data. A number of these CBM and CS data collections have been registered in the INTAROS Data Catalogue. Some of these collections are hosted and sustained by large international programs such as PISUNA, eBird, Secchi Disk Study and GLOBE Observer. Registration in the INTAROS Data Catalogue contributes to making these important data collections better known in a wider community of users with a vested interest in the Arctic. It also enables sharing of metadata through open standards for inclusion in other Arctic data systems. This catalogue is a key component in INTAROS, enabling users to search for data across the targeted spheres to assess their usefulness in applications and geographic areas. The catalogue is based on a world-leading system for data management, the Comprehensive Knowledge Archive Network (CKAN). With rich functionality offered out of the box combined with a flexible extension mechanism, CKAN allows for quickly setting up a fully functional data catalogue. The CKAN open-source community offers numerous extensions that can be used as-is or adapted to implement customised functionality for specific user communities. To hold additional metadata elements requested by the partners we modified the standard database schema of CKAN. The presentation will focus on the current capabilities and plans for sustaining and enhancing the INTAROS Data Catalogue.
Urban surface temperature observations from ground-based thermography: intra- and inter-facet variability
Authors: Morrison William , Kotthaus Simone , Grimmond Sue
Published: March 2021

In this study (Morrison et al., 2021) ground based thermal cameras are used to observe urban surface temperatures (Ts) with an unprecedented combination of: temporal and spatial resolution (5 min and ~ 0.5 m → 2.5 m), spatial extent (3.9 ha), instrument number (6 static cameras) and surface heterogeneity (mixed high rise and vegetation). The camera images are classified by geometry and material properties (surface orientation, albedo, solar irradiance, and shadow history). Unlike previous methods, pixels are objectively classified using sensor view modelling and a detailed three-dimensional surface model (430 m × 430 m extent). From detailed source area analysis, the cameras are shown to observe 9.5% of the study area. Across all camera pixels, the 5th - 95th percentile Ts range is 37.5 K around midday. Roofs Ts has the greatest diurnal range (290.6 K → 329.0 K). Ts differences across sloped roofs with different sun-surface geomeetry reach 23.3 K. Walls of different cardinal orientations consistently differ by >10 K between 10:00 and 15:00. High temporal resolution (5 min) shadow tracking from the classified images is used to model cooling rates, where recently shaded (<30 min) ground can be 18.6 K warmer than equivalent unshaded Ts. West walls remain warm past sunset and are 1.2 K warmer than north walls at 23:00 (~4 h after sunset). Recently shaded walls cool exponentially to ambient Ts at a similar rate as the ground, but four times slower than roofs. The observaiton methods and observed Ts characteristics are anticipated to have a wide range of applications (e.g. informing future ground-based thermogragy campaign setups, evaluation of urban surface energy balance models, ground-truthing of satellite thermal remote sensing).

 

Morrison, W., Kotthaus, S. and Grimmond, S. (2021) ‘Urban surface temperature observations from ground-based thermography: intra- and inter-facet variability’, Urban Climate, 35, p. 100748. doi: 10.1016/j.uclim.2020.100748.

 
The role of seagrass leaf litter in the SGD-derived nutrient fluxes in Cala Pudent (Menorca, western Mediterranean)
Authors: Rodriguez-Puig Julia , Alorda-Montiel Irene , Diego-Feliu Marc , Alorda-Kleinglass Aaron , Rodellas Valentí , García-Orellana Jordi
Published: March 2021

The assessment of the biogeochemical cycles in coastal environments often relies on riverine inputs as the main source of nutrients and other dissolved compounds from land to the ocean. However, the discharge of groundwater through continental margins, commonly known as Submarine Groundwater Discharge (SGD), is also recognized as relevant sources of nutrients to the coastal ocean, particularly in oligotrophic and semi-arid environments, such as the Mediterranean Sea. In this study, we use radioactive tracers (radium isotopes and radon) to i) quantify the magnitude of SGD-driven nutrient fluxes to a Mediterranean cove (Cala Pudent, Menorca, Balearic Islands) and ii) characterize the nutrient transformations occurring in the beach before groundwater discharges to the sea. Cala Pudent is a limestone coastal cove with a restricted connection to the open sea. In this system, groundwater from a permanent spring infiltrates through an organic substrate dominated by thick deposits of seagrass (Posidonia oceanica) leaf litter and flows into the sea. This substrate, together with the dynamic groundwater-seawater mixing, are chiefly influencing the nutrient enrichment and transformation occurring in the beach and thus modulating the SGD-derived nutrient input to the sea. The ecological implications of these inputs are also assessed, particularly for the Posidonia oceanica and Cymodocea nodosa meadows located near the study site.  

 
Understanding dilatancy in rocksalt: a microphysical model of rocksalt at the grain-scale
Authors: van Oosterhout Bart , Spiers Chris , Hangx Suzanne
Published: March 2021

The use of underground repositories excavated in low-permeability formations, such as rock salt, to store high-level, radioactive waste requires the analysis of its isolation properties. Underground excavation disturbs the original stress state of the rocksalt, resulting in a deviatoric stress distribution around the walls of excavated galleries and boreholes. At high deviatoric stresses and low confinement, dense rocksalt produces an increase in porosity and permeability. The extent of dilatancy in this disturbed zone, as well as the impact of dilatancy on the transport properties, are important for assessing the safety of radio-active waste disposal as well as the integrity of salt caverns and boreholes in the context of energy storage, brine cavern abandonment and gas well abandonment.  

The stress conditions at which dilatancy occurs have been measured experimentally, and are typically determined on the basis of macroscopic (sample-scale) measurements of volumetric strain and permeability, and/or acoustic velocity changes or emissions. However, the detailed mechanisms causing dilatancy at the grain-scale are poorly understood. We have developed a microphysical model for dilatancy in rocksalt, both under dry and wet conditions, including mechanisms such as slip and opening of grain boundaries. This model enables us to describe and predict the dilatancy behaviour of rocksalt based on physical, mechanical and chemical processes. The model is presently being independently verified through comparison with existing literature data, and new experiments.
Spatial patterns of high-elevation precipitation observed through spaceborne precipitation radars
Authors: Hirose Masafumi , Fujinami Hatsuki
Published: March 2021

Spaceborne-radar precipitation products at high altitudes entail close attention to geographically inherent retrieval uncertainties. The lowest levels free from surface clutter are ~1 km higher in rugged mountainous areas than those over flatlands. The clutter-removal filter masks precipitation echoes at altitudes below 3 km from the surface at the swath edge over narrow valleys in the Himalayas. In this study, precipitation profiles at levels with clutter interference were estimated using an a priori precipitation profile dataset based on near-nadir observations. The corrected precipitation dataset was generated based on the Tropical Rainfall Measuring Mission Precipitation Radar (TRMM PR) product at a spatial resolution of 0.01° around the Trambau Glacier terminus in the Nepal Himalayas, where ground observation sites were installed in 2016. The occurrence frequency of precipitation was considerably small compared with the in situ observation because of limitations in the sensor sensitivity. The occurrence frequency of light precipitation is increased by the Dual-frequency Precipitation Radar (DPR) onboard the Global Precipitation Measurement (GPM) Core Observatory, and the low-level precipitation profile correction mitigates underestimation bias by ~10%. In this presentation, the detectability of fine-scale precipitation climatology and the local characteristics of its diurnal variation at high altitudes are discussed based the combination of the TRMM PR and GPM DPR products.
Importance of gravity wave forcing for springtime southern polar vortex breakdown as revealed by ERA5
Authors: Gupta Aman , Birner Thomas , Doernbrack Andreas , Polichtchouk Inna
Published: March 2021

Planetary waves and gravity waves are the key drivers of middle atmospheric circulation and variability. While planetary waves are well resolved in climate models, inaccuracies in representation of gravity waves in climate models persist. Inaccuracies in representation of gravity waves limit our understanding of the planetary wave-gravity wave interactions that can be crucial during the Antarctic polar vortex breakdown. Moreover, "missing" gravity wave drag around 60oS in the upper stratosphere is considered to be responsible for the "cold-pole" bias in comprehensive climate models that employ parameterizations to appproximately represent the gravity wave drag.

We illustrate the strength of the high-resolution ERA-5 reanalysis in resolving a broad spectrum of gravity waves in southern hemisphere midlatitudes and to estimate their contribution to the momentum budget around 60oS. We find that most of the resolved mountain waves excited over the Andes and Antarctic peninsula propagate away from their source and deposit momentum around 60oS over the Southern Ocean. Further, a composite analysis around 60oS during the vortex breakdown period using ERA-5 reveals considerably large fractional contribution of resolved + parameterized GWD towards the vortex deceleration. Upto 30 days prior to the breakdown, a balance between the Coriolis acceleration and the planetary wave deceleration provides a weak net deceleration of the mean winds, following which, they provide a net acceleration of the mean winds. The gravity waves, however, provide a steady deceleration of the mean winds throughout the breakdown period. The resolved drag in ERA-5 accounts for as much as one-fourth of the zonal wind deceleration at 60oS and 10 hPa, while the parameterized drag in ERA-5 accounts for more than one-half of the zonal wind deceleration.  The findings establish the crucial role of gravity waves in wintertime stratospheric circulation and opens avenues for further stratospheric gravity wave analysis using ERA-5.
Thermal fractionation of soil organic matter produces fine-scale distributions of SOM age
Authors: Stoner Shane , Sierra Carlos , Schrumpf Marion , Dötterl Sebastian , Trumbore Susan
Published: March 2021

Soil organic matter (SOM) is a complex collection of organic molecules of varying origin, structure, chemical activity, and mineral association. A wide array of laboratory methods exists to separate SOM based on qualitative, biological, chemical, and physical characteristics. However, all present conceptual and logistical limitations, including the requirement of a substantial amount soil material.

An newly applied alternative method of fractionation relies on a conceptual analogue between biochemical stability in soil and thermal stability, e.g. more persistent SOM will require higher temperatures (greater energy inputs) to decompose than less persistent SOM. This accounts for both chemical complexity and mineral association as main factors in determining SOM persistence.

In this method, carbon is released by heating SOM to 900°C at a constant rate. The peaks of carbon release are grouped into activation energy pools, CO2 is collected, and analyzed for 13C and 14C. We seek to describe in finer detail the distribution of soil radiocarbon by adding another fractionation step following a different paradigm of SOM stability, and explore mineralogical effects on SOM quality and stability using thermal analysis, radiocarbon, and gas chromatography.

Here, we analyzed bulk soil and soil fractions derived from density separation and chemical oxidation, as well as mineral horizons dominated by diverse mineralogies. Density fractions contained a wide range of radiocarbon activities and that young SOM is stabilized across multiple fractions, likely due to organomineral complexation. Initial results showed that soil minerals with limited stabilization potential released C at lower temperatures than those with diverse stabilization mechanisms. High-temperature sub-fractions contained the oldest carbon across fractions and minerals, thus supporting the assumption that thermal stability can be used as a limited analogue for stability in soil. We present a fine-scale distribution of radiocarbon in SOM and discuss the potential of this method for comparison with other fractionation techniques.
Towards Large-area Dynamic Modeling of Landslides Hazard and Risk with Spatiotemporal Point Processes
Authors: Pittore Massimiliano , Oezturk Ugur , Steger Stefan
Published: March 2021

Landslides are one of the most relevant natural threat in mountainous regions, resulting each year in billion of direct and indirect losses incurred worldwide. Furthermore, it is widely acknowledged that these processes are both strongly dependent on local geomorphological, geological and environmental features and highly sensitive to weather- and climate-related events such as intense precipitation or snowmelt. However, most regional landslides hazard and risk models to date struggle capturing this complex interplay of quasi-static and dynamic drivers and triggering factors, hence severely hampering their operational use for implementing timely risk mitigation and adaptation measures.

We aim to introduce a sound and relatively straightforward geostatistical approach to landslides hazard and risk modelling based on heterogeneous spatiotemporal point processes, which has potential for the assimilation of empirical observations from different sources (including, e.g., remote sensing) for iterative calibration and free from thresholds of continuous monitoring parameters. Such approach could be efficiently used to obtain large-area, near-real time stochastic simulation of landslide processes as input to further risk analysis and management activities by civil protection authorities and policy planners. Perspectives and limitations of the proposed approach stemming from a preliminary exemplification in a case study in Central Asia will be outlined and discussed.
Quasi real-time monitoring of the ionosphere plasma irregularities by the records of the Swarm mission
Authors: Kovacs Peter , Heilig Balazs
Published: March 2021

The magnetic and plasma observations of Low-Earth orbit (LEO) space missions represent not only the dynamical state of the ionosphere but also the physical variations of its electromagnetically connected surroundings, i.e. of the plasmasphere and magnetosphere, as well as of their driver, the solar wind. The monitoring of the ionosphere plasma variables is therefore a big asset for the study of our space environment in broad spatial region. Within the framework of the EPHEMERIS project supported by ESA, we aim at investigating two ionosphere phenomena that exhibit close relationship to global physical processes and space weather activity. We use the magnetic and plasma records of the LEO Swarm mission. First, we investigate the temporal and spatial occurrences of the mid-latitude ionosphere trough (MIT), a typical feature of the topside sub-auroral ionosphere appearing as a few degree wide depleted zone, where electron density (Ne) drops by orders of magnitude. It is shown that the locations of MITs are excellent proxies for the detection of the plasmapause position as well as of the equatorward edge of the auroral oval. Secondly, we monitor the irregular fluctuations of the magnetic field along the Swarm orbits via their intermittent behaviour. A new index called intermittency index (IMI) is introduced for the quantitative exemplification of the spatial and temporal distribution of irregular variations at the Swarm spacecraft altitudes. The paper focuses on the introduction of the methodology of IMI time-series compilation. Since IMIs are deduced via a statistical approach, we use the 50 Hz sampling frequency magnetic field records of the mission. We show that most frequently, the ionosphere magnetic field irregularities occur at low-latitudes, about the dip equator and at high latitudes, around the auroral region. It is conjectured that the equatorial events are the results of equatorial spread F (ESF) or equatorial plasma bubble (EPB) phenomena, while the auroral irregularities are related to field-aligned currents (FAC). The ionosphere plasma irregularities may result in the distortion or loss of GPS signals. Therefore our analysis also concerns the investigation of the correlation between observed intermittent events in the ionosphere and contemporary GPS signal loss events and scintillations detected both by on-board Swarm GPS receivers and ground GNSS stations.
Assessing the effectiveness of an urban CO2 monitoring network through the COVID-19 lockdown natural experiment
Authors: Lian Jinghui , Lauvaux Thomas , Utard Hervé , Broquet Grégoire , Bréon François-Marie , Ramonet Michel , Laurent Olivier , Cucchi Karina , Ciais Philippe
Published: March 2021

Quantitative monitoring of CO2 sources and sinks over cities is needed to support the urban adaptation and mitigation measures, but it is a challenging task. The Paris metropolitan area is a highly built-up and densely populated region in France. The two national COVID-19 forced confinements that are 1) effective on March 17th, with a duration of 55 days until May 11th, 2) effective on October 30th, with a duration of 46 days until December 15th provide an opportunity to assess the behaviour and robustness of the dedicated atmospheric inversion system for estimating the city-scale CO2 emissions.

In this study, the atmospheric Bayesian inversion approach that couples six in-situ continuous CO2 monitoring stations with the WRF-Chem transport model at 1-km horizontal resolutions has been used to quantify the impacts of lockdown on CO2 emissions for the Paris megacity. The prior emission estimate was from the Origins inventory, a near-real-time dataset of fossil fuel CO2 emissions by sector (transportation, residential, tertiary, industry and sink) at 1km² and hourly resolution recently developed by Origins.earth. Estimates of CO2 emissions were retrieved from the inversion by assimilating CO2 concentration gradients between upwind-downwind stations using a refined configuration of the existing Parisian inversion system developed by Bréon et al. (2015) and Staufer et al. (2016). A set of experiments was performed to assess the sensitivity of the posterior CO2 estimates to the changes in different inversion setups, including the selection of observations, prior flux uncertainties and error correlations. We also analyzed the potential contribution of the expanding CO2 monitoring network, in particular the two newly built urban stations in the city center since 2014, to the inverse modeling systems.

The optimized CO2 estimates show decreases of around 42% and 25% in anthropogenic CO2 emissions during the first and second lockdowns respectively when compared with the same period in past two years. Both lockdown emission reduction estimates from the inversion are consistent with recent estimates from activity data (resp. 37% and 19%), suggesting that our near-real time monitoring system is able to detect and quantify short-term variations at the whole-city level.
On the data synergy effect of large-sample multi-physics catchment modeling with machine learning
Authors: Shen Chaopeng , Rahmani Farshid , Fang Kuai , Wei Zhi , Tsai Wen-Ping
Published: March 2021

Watersheds in the world are often perceived as being unique from each other, requiring customized study for each basin. Models uniquely built for each watershed, in general, cannot be leveraged for other watersheds. It is also a customary practice in hydrology and related geoscientific disciplines to divide the whole domain into multiple regimes and study each region separately, in an approach sometimes called regionalization or stratification. However, in the era of big-data machine learning, models can learn across regions and identify commonalities and differences. In this presentation, we first show that machine learning can derive highly functional continental-scale models for streamflow, evapotranspiration, and water quality variables. Next, through two hydrologic examples (soil moisture and streamflow), we argue that unification can often significantly outperform stratification, and systematically examine an effect we call data synergy, where the results of the DL models improved when data were pooled together from characteristically different regions and variables. In fact, the performance of the DL models benefited from some diversity in training data even with similar data quantity. However, allowing heterogeneous training data makes eligible much larger training datasets, which is an inherent advantage of DL. We also share our recent developments in advancing hydrologic deep learning and machine learning driven parameterization.
Bioenergy potentials from recently abandoned cropland under the land-energy-water nexus
Authors: Næss Jan Sandstad , Cavalett Otavio , Cherubini Francesco
Published: March 2021

Bioenergy plays a key role in scenarios limiting global warming below 2°C in 2100 relative to pre-industrial times. Land availability for bioenergy production is constrained due to competition with agriculture, nature conservation and other land uses. Utilizing recently abandoned cropland to produce bioenergy is a promising option for gradual bioenergy deployment with lower risks of potential trade-offs on food security and the environment. Up until now, the global extent of abandoned cropland has been unclear. Furthermore, there is a need to better map bioenergy potentials, taking into account site-specific conditions such as local climate, soil characteristics, agricultural management and water use.

Our study spatially quantify global bioenergy potentials from recently abandoned cropland under the land-energy-water nexus. We integrate a recently developed high-resolution satellite-derived land cover product (European Space Agency Climate Change Initiative Land Cover) with an agro-ecological crop yield model (Global Agro-Ecological Zones 3.0). Abandoned cropland is mapped as pixels transitioning from cropland to non-urban classes. We further identify candidate areas for nature conservation and areas with increased pressure on water resources. Based on climatic conditions, soil characteristics and agricultural management levels, we spatially model bioenergy yields and irrigation water use on abandoned cropland for three perennial grasses. We compute and analyze bioenergy potentials for 296 different variants of management factors and land and water use constraints. By assessing key energy, water and land indicators, we identify optimal bioenergy production strategies and site-specific trade-offs.

We found 83 million hectares of abandoned cropland between 1992 and 2015, equivalent of 5% of today’s cropland area. Bioenergy potentials range between 6-39 exajoules per year (EJ yr-1) (11-68% of today’s bioenergy demand), depending on agricultural management, land availability and irrigation water use. We further show and extensively discuss site-specific trade-offs between increased bioenergy production, land-use and water-use. Our high-end estimate (39 EJ yr-1) relies on complete irrigation and land availability. When acknowledging site-specific trade-offs on water resources and nature conservation, a potential of 20 EJ yr-1 is achievable without production in biodiversity hotspots or irrigation in water scarce areas. This is equal to 8-23% of median projected bioenergy demand in 2050 for 1.5°C scenarios across different Shared Socio-economic Pathways. The associated land and water requirements are equal to 3% of current global cropland extent and 8% of today’s global agricultural water use, respectively.
On combining GUI desktop GIS with computer clusters & cloud resources, the role of programming skills and the state of the art in GUI driven GIS HPC applications
Authors: Ernst Sebastian M.
Published: March 2021

The Free and Open Source Software (FOSS) ecosystem around Geographic Information System (GIS) is currently seeing rapid growth – similar to FOSS ecosystems in other scientific disciplines. At the same time, the need of broad programming and software development skills appears to become a common theme for potential (scientific) users. There is a rather clear boundary between what can be done with Graphical User Interface applications such as QGIS only on the one hand side and contemporary software libraries on the other hand side – if one actually has the required skillet to use the latter. Practical experience shows that more and more types of research require far more than just rudimentary software development skills. Those can be hard to acquire and distract from the actual scientific work at hand. For instance the installation, integration and deployment of much desired software libraries from the field of high-performance computing (HPC) for e.g. general-purpose computing on graphics processing units (GPGPU) or computations on clusters or cloud resources is very often becoming an obstacle on its own. Recent advances in packaging and deployment systems around popular programming language ecosystems such as Python enable a new kind of thinking, however. Desktop GUI applications can now much more easily be combined with the mentioned type of libraries, which lowers the entry barrier to HPC applications and the handling of large quantities of data drastically. This work aims at providing an overview of the state of the art in this field and showcasing possible techniques.
Hydrological impact of the new ECMWF multi-layer snow scheme
Authors: Arduini Gabriele , Zsoter Ervin , Cloke Hannah , Stephens Elisabeth , Prudhomme Christel
Published: March 2021

Snow processes, with the water stored in the snowpack and released as snowmelt, are very important components of the water balance, in particular in high latitude and mountain regions. The evolution of the snow cover and the timing of the snow melt can have major impact on river discharge. Land surface models are used in Earth System models to compute exchanges of water, energy and momentum between the atmosphere and the surface underneath, and also to compute other components of the hydrological cycle. In order to improve the snow representation, a new multi-layer snow scheme is under development in the HTESSEL land surface model of the European Centre for Medium‐Range Weather Forecasts (ECMWF) Integrated Forecasting System (IFS), to replace the current single-layer snow scheme used in HTESSEL. The new scheme has already been shown to improve snow and 2‐metre temperature, while in this study, the wider hydrological impact is evaluated and documented.

The analysis is done in the reanalysis context by comparing two ERA5-forced offline HTESSEL experiments. The runoff output of HTESSEL is coupled to the CaMa-Flood hydrodynamic model in order to derive river discharge. The analysis is done globally for the period between 1980-2018. The evaluation was carried out using over 1000 discharge observation time-series with varying catchment size. The hydrological response of the multi-layer snow scheme is generally positive, but in some areas the improvement is not clear and can even be negative with deteriorated signal in river discharge. Further investigation is needed to understand the complex hydrological impact of the new snow scheme, making sure it contributes to an improved description of all hydrological components of the Earth System.
The enigma on the date of the 79 AD Vesuvius eruption: lesson from grape archaeobotanical remains
Authors: D'Auria Alessia , De Micco Veronica , Di Pasquale Gaetano
Published: March 2021

The sites destroyed by the eruption of Mt. Vesuvius (southern Italy) in AD 79 provide a complete picture of life in Campania during the 1st century AD. Among the archaeological areas, the Vesuvian region constitutes an exceptional case for the wealth of botanical remains. The presence and quantity of these materials in the Vesuvian area depend on the heat of volcanic materials such as the fallout of pumice, ash and gas emitted during the eruption. Therefore, this eruption has determined, together with archaeological finds, the preservation of thousands of botanical remains represented especially by food plants like cereals (i.e. Triticum dicoccum; Hordeum vulgare; Setaria italica) and pulses (i.e. Vicia faba var. minor; Lens culinaris), olive (Olea europaea var. europaea) and grape remains (Vitis vinifera subsp. vinifera). The eruption date is still matter of discussion. Indeed, the classical theory according to the story described by Pliny the Young indicates the 24 August as the date of eruption, while recently some scholars hypothesize that the correct day is the 24 October 79 AD. The discrepancy is probably due to a wrong medieval transcription of the original text by Pliny. Some botanical remains might help solve this  dispute. For example, the analysis of wood anatomical traits can be targeted to detect how much of the yearly wood increment had been produced at the time of eruption. Also the variation of the conduit anatomical traits in the last wood increment might be an indicator to reconstruct the season when the vines were destroyed. In this study, we used leaf and wood remnants of V. vinifera to determine the phenological phase of the vines at the time of eruption in order to provide evidence for supporting one of the two hypotheses. More specifically, a morpho-anatomical characterization was carried out on wood samples coming from Herculaneum ruins (Ercolano), and on tendrils and leaves with evidence of pruning coming from Oplontis site (Torre Annunziata). This study case is a proof of concept of the application potential of a trait-based approach in palaeobotany.
Produced water treatment and reuse in oil and gas industry- Mathematical modelling and optimisation for infrastructure utilisation  
Authors: AlEdan Afrah , Erfani Tohid
Published: March 2021

Currently, oil and gas industry dispose the produced water under the ground without treatment and with minimal consideration on the beneficial reuse applications. Yet, in recent years and in response to the worldwide water shortage concerns, produced water management and treatment has gained more attention and interest. Managing produced water is subject to different limitations specially if it is done for offsite applications. This includes the consideration of transportation cost and removal of dispersed and dissolved oil, metals, ammonia, salinity, alkalinity and ion toxicity for human and agricultural use which can result in a greater economic cost in terms of chemical usage and desalination operations. The importance of properly managing produced water is mainly rely on the clear vision of the treating method used which must be defined based on regulatory parameters and reuse standards. This study investigates mathematical modelling and optimisation to include the reuse specification into the produced water quality management and discusses its implication.