bluuebunny/crossref_metadata_2025 huggingface dataset:
Advancing the Water Footprint into an instrument to support achieving the SDGs
Authors: Semmling Elsa , Berger Markus , Campos Jazmin , Carolli Mauro , Dantas Iana , Kosatica Ervin , Kramer Annika , Mikosch Natalia , Nouri Hamideh , Schlattmann Anna , Schmidt Falk , Schomberg Anna
Published: March 2021

The water footprint has developed into a widely-used concept to examine water use and resulting local impacts caused during agricultural and industrial production. Building on recent advancements in the water footprint concept, it can be an effective steering instrument to support, inter alia, achieving sustainable development goals (SDGs) - SDG 6 in particular. Within the research program “Water as a Global Resource” (GRoW), an initiative of the Federal Ministry for Education and Research, a number of research projects currently apply and enhance the water footprint concept in order to identify areas where water is being used inefficiently and implement practical optimization measures. We aim to raise awareness on the potential of the water footprint concept to inform decision-making in the public and private sectors towards improved water management and achieving the SDGs. In particular, we show how modern water footprint methods and tools developed in GRoW can inform policy planning towards more sustainable use of water resources at various levels. They can also support producers in determining their indirect water use and associated impacts in supply chains, in addition to their (often comparably low) direct water use at production sites. Finally, we show how the water footprint can raise awareness and inform consumers about the hidden water use and resulting impacts of daily products and services.
Atmospheric phenomena affecting the methane lifetime on Mars
Authors: Grenfell John Lee , Wunderlich Fabian , Sinnhuber Miriam , Herbst Konstantin , Scheucher Markus , Gebauer Stefanie , Rauer Heike
Published: March 2021

We investigate a range of atmospheric phenomena concerning their potential to address the Martian methane lifetime discrepancy. This refers to the over-estimate of the modelled lifetimes compared to observations by a factor of up to six hundred. We apply a newly developed atmospheric photochemical model where we vary in a Monte Carlo approach the chemical rate and Eddy mixing coefficients within their current uncertainties. We also investigate the effect of air shower events due to galactic cosmic rays and solar cosmic rays. Our results suggest that the current uncertainty in chemical rates and transport together with seasonal changes in the water column can likely account for up to a factor of about thirty in the Mars methane lifetime discrepancy whereas the air shower effects are likely to be of secondary importance.
Fluid-total pressure partitioning in shear banding poro-visco-elasto-plastic media
Authors: Alkhimenkov Yury , Quintal Beatriz , Podladchikov Yury
Published: March 2021

Fluid injection is one of the main triggers of induced seismicity. Accurate numerical modeling of such processes is crucial for the safety of many affected regions. We propose a high-resolution numerical simulation of the strain localization in elasto-plastic and poro-visco-elasto-plastic media with a particular focus on the fluid pressure distribution. The resolution of our numerical model is 10000 by 10000 grid cells. The simulation is accelerated using graphical processing units (GPUs), thus, the total simulation time is in the order of a few minutes. We implement a pressure-dependent Mohr-Coulomb plastic law and study the influence of fluid pressure on the triggering of shear bands. Mean stress is partitioned between fluid pressure and total pressure. This study is particularly important since the effective stress law (the difference between fluid and total pressures) controls brittle failure. We vary viscosity and permeability as well as initial conditions for fluid pressure to explore the physics of shear bands nucleation. We show that fluid pressure in hydro-mechanically coupled media significantly affects the strain localization pattern compared to only elasto-plastic media. Permeability and viscosity are important parameters that control the fluid pressure distribution in the localized shear zones. This work is a preliminary study to model induced seismicity due to the fluid injection in fluid-saturated rocks described as fully coupled poro-visco-elasto-plastic media.
The relevance of soil moisture for land carbon sink projections
Authors: Padrón Ryan S. , Gudmundsson Lukas , Humphrey Vincent , Seneviratne Sonia I.
Published: March 2021

During the last century the land biosphere has been a sink of anthropogenic carbon emissions to the atmosphere. Here we analyze future projections of terrestrial carbon fluxes from multiple Earth system models participating in the sixth phase of the Coupled Model Intercomparison (CMIP6) with a focus on the evolution of the land carbon sink under increasing atmospheric carbon concentrations and associated climate change. We find that interannual variability in the land carbon sink given by the net biome production (NBP) is dominantly related to variability in soil moisture across most models and regions. Nevertheless, several models indicate that temperature variations are more strongly related to NBP variations in the core of the Amazon. Model trends in NBP are relatively well explained by trends in both soil moisture and temperature. Finally, the CMIP6 ensemble has a large inter-model spread of the average land carbon sink projected for the end of the century (2071–2100). We show that inter-model differences in soil moisture conditions and in the sensitivity of NBP to soil moisture contribute to explain this spread, particularly in boreal forest regions. Overall, our study highlights the influence of water-carbon interactions on the future evolution of the terrestrial carbon cycle. We suggest that efforts to constrain Earth system model projections should jointly constrain soil moisture and carbon fluxes.
Porous media as a canvas for hydro-bio-geo-chemical processes: Facing the challenges
Authors: Sanchez-Vila Xavier
Published: March 2021

The more we study flow and transport processes in porous media, the larger the number of questions that arise. Heterogeneity, uncertainty, multidisciplinarity, and interdisciplinarity are key words that make our live as researchers miserable… and interesting. There are many ways of facing complexity; this is equivalent as deciding what colors and textures to consider when being placed in front of a fresh canvas, or what are the sounds to include and combine in a music production. You can try to get as much as you can from one discipline, using very sophisticated state-of-the-art models. On the other hand, you can choose to bring to any given problem a number of disciplines, maybe having to sacrifice deepness in exchange of the better good of yet still sophisticated multifaceted solutions. There are quite a number of examples of the latter approach. In this talk, I will present a few of those, eventually concentrating in managed aquifer recharge (MAR) practices. This technology involves water resources from a myriad of perspectives, covering from climate change to legislation, from social awareness to reactive transport, from toxicological issues to biofilm formation, from circular economy to emerging compounds, from research to pure technological developments, and more. All of these elements deserve our attention as researchers, and we cannot pretend to master all of them. Integration, development of large research groups, open science are words that will appear in this talk. So does mathematics, and physics, and geochemistry, and organic chemistry, and biology. In any given hydrogeological problem you might need to combine equations, statistics, experiments, field work, and modeling; expect all of them in this talk. As groundwater complexity keeps amazing and mesmerizing me, do not expect solutions being provided, just anticipate more and more challenging research questions being asked.
Assuring safe port navigation by assimilating from data sources with different spatial and temporal scales
Authors: Phillips Benjamin , Higham Jonathan , Plater Andrew , Leonardi Nicoletta , Arribas-Bel Daniel , Bird Cai , Sinclair Alex
Published: March 2021

Safe port operations require accurate information on vessel location, routine monitoring and maintenance of navigation channels, and accurate information on coastal hydrodynamics.  Accurate bathymetric data enables port operators to have a high level of confidence in assuring sufficient water depth for vessels, and to effectively direct surveying and dredging operations to maintain navigation routes. However, this is not readily facilitated for nearshore approaches where migrating sandbanks and shoals pose a hazard to shipping.

In this presentation, we present an innovative and novel data assimilation method of combining satellite data, hydrodynamic model (Delft3D) outputs and land-based radar data using machine learning and advanced statistical methods (Dynamic Mode Decomposition). To assimilate these data we use machine learning and statistical methods to detect "patterns" or "modes" in near- and far-field wave climate that are attributable to sub- and intertidal bathymetry and changes therein. We then combine the dominant modes into a low-order representation of the system, providing informed estimates of spatial resolutions and temporal scales where no measurements are physically performed. Satellite data and associated hydrodynamic model outputs are used to provide information on wave direction and height for the offshore-nearshore approaches while land-based marine radar located in the appropriate position provide wave data at higher temporal and more local spatial resolution. 

The data nexus we present in this presentation demonstrates significant improvements in capability above and beyond the use of a given technology in isolation.
Estimation of water table, soil states and parameters of integrated subsurface-land surface models by data assimilation
Authors: Hung Ching Pui , Schalge Bernd , Baroni Gabriele , Sanchez Emilio , Cirpka Olaf , Kollet Stefan , Neuweiler Insa , Simmer Clemens , Hendricks Franssen Harrie-Jan
Published: March 2021

Estimating states and fluxes of the water cycle with terrestrial system models needs a large amount of input data, including soil and vegetation parameters, resulting in large uncertainties in model predictions. Assimilation of pressure head and/or soil moisture data can better constrain states and parameters of a terrestrial system model. Here we assimilate pressure head data and soil moisture data in a terrestrial system model over the Neckar catchment (13928 km2) with a spatial horizontal resolution of 800 m. We use the Terrestrial System Modeling Platform (TSMP), which consists of an atmospheric model component (not used in this work), the Community Land Model version 3.5 (CLM3.5), and the subsurface hydrological model Parflow, coupled by OASIS. TSMP is coupled to the Parallel Data Assimilation Framework (PDAF), which allows the assimilation of land surface and subsurface observations to estimate the model states and parameters. In this work the localized Ensemble Kalman Filter (LEnKF) was used to update hydraulic head, soil moisture and/or saturated hydraulic conductivity by assimilating hydraulic head or in situ soil moisture observations for a period of one year. Ensembles of soil properties, leaf area index and atmospheric forcings were generated. The ensemble of atmospheric forcings considered correlations among four variables, and spatio-temporal correlations of the atmospheric variables using a geostatistical procedure. The characterization of the water table depth and river discharge without data assimilation and for different scenarios of pressure head and soil moisture data assimilation were compared.
Advanced pattern techniques in weather and climate science
Authors: Kwasniok Frank
Published: March 2021

This presentation discusses two examples of the use of advanced pattern techniques in weather and climate science. Firstly, optimal mode decomposition (OMD) is employed for linear inverse modelling of large-scale atmospheric flow. The OMD technique determines a low-rank approximation to a high-dimensional dynamical system in terms of a linear empirical model; a set of patterns and a system matrix are identified simultaneously by maximising the explained predictive variance. The method is exemplified on a quasi-geostrophic atmospheric model with realistic mean state and variability. Considerable improvements in prediction skill are observed compared to the traditional approach based on principal components or dynamic mode decomposition (DMD). Secondly, nonlinear principal prediction patterns are used for stochastic subgrid-scale modelling. Pairs of predictor-predictand patterns are determined in the space of the resolved variables and the space of the subgrid forcing, respectively, and linked in a predictive manner. The predictor patterns may contain nonlinear functions of state variables. On top of this deterministic subgrid model the predictand patterns are forced stochastically. The approach is demonstrated on the two-scale Lorenz 1996 system.
Lessons learned from the implementation of the near real-time S2S4E Decision Support Tool
Authors: Palma Lluís , Manrique Andrea , Lledó Llorenç , Nicodemou Andria , Bretonnière Pierre-Antoine , Pérez-Zanón Núria , Ho An-chi , Soret Albert
Published: March 2021

Under the context of the H2020 S2S4E project, industrial and research partners co-developed a fully-operational Decision Support Tool (DST) providing during 18 months near real-time subseasonal and seasonal  forecasts tailored to the specific needs of the renewable energy sector. The tool aimed to breach the last mile gap between climate information and the end-user by paying attention to the interaction with agents from the sector, already used to work with weather information, and willing to extend their forecasting horizon by incorporating climate predictions into their daily operations.

With this purpose, the tool gathered a heterogeneous dataset of seven different essential climate variables and nine energy indicators, providing for each of them bias-adjusted probabilistic information paired with a reference skill metric. To achieve this, data from state-of-the-art prediction systems and reanalysis needed to be downloaded and post-processed, fulfilling a set of quality requirements that ensure the proper functioning of the operational service. During the design, implementation, and testing phases, a wide range of scientific and technical choices had to be made, making clear the difficulties of transferring scientific research to a user-oriented real-time service. A brief showcase will be presented, exemplifying the different tools, methodologies, and best practices applied to the data workflow, together with a case study performed in Oracle’s cloud infrastructure. We expect that by making a clear description of the process and the problems encountered, we will provide a valuable experience for both, upcoming attempts of similar implementations, and the organizations providing data from climate models and reanalysis.
Preliminary spectral and geological analyses of the Degas crater on Mercury - supporting the SIMBIO-SYS instrument onboard BepiColombo
Authors: Bott Nicolas , Barraud Océane , Guzzetta Laura
Published: March 2021

The BepiColombo spacecraft was launched in October 19th, 2018 (local time) towards Mercury, carrying 16 instruments in two orbiters (MPO and MMO). Among this impressive set of devices, the SIMBIO-SYS (Spectrometer and Imagers for MPO BepiColombo Integrated Observatory SYStem) instrument [Cremonese et al., 2020] will map at an unprecedented high resolution the surface of the innermost planet of the Solar system, thanks to 3 cameras: STC (Stereo Channel), a stereo camera; HRIC (High spatial Resolution Imaging Channel), a multispectral camera with a very high spatial resolution; VIHI (Visible Infrared Hyperspectral Imager channel), a hyperspectral imager to with a good spectral resolution and a good S/N ratio. The last one aims to map the global mineralogical composition of Mercury, which has not yet been precisely determined due to the absence of diagnostic absorption bands in the remote sensing data of the previous MESSENGER mission [Izenberg et al., 2014]. The choice and the list of targets SIMBIO-SYS will have to analyse are still in progress and are continuously updated. Therefore, preliminary studies of potential targets of interest can be very useful to support their selection.

For that purpose, we started investigating a particular crater, Degas, which occurs in the Shakespeare quadrangle (H-03) [Guzzetta et al., 2017; Bott et al., 2019], located at mid-latitudes of the northern hemisphere of Mercury (37.08 ◦ N - 232.66 ◦ E). Its well-preserved ray system of ejecta are a strong hint in favor of its chronostratigraphic classification as a Kuiperian (-1 Gyr – today) crater [Banks et al., 2017]. By using MESSENGER data, we analysed the Degas crater with a three-fold approch: a multispectral analysis based on MDIS-WAC data have been combined with a spectroscopic analysis of MASCS data and a geological analysis based on MDIS-NAC images. Here, we would like to present the first outputs of our works, including a set of color and monochrome mosaics, spectral parameters maps and spectra of each kind of terrain identified with the mosaics, and the first results of the high-resolution geological mapping of the Degas crater performed on a NAC images mosaic of 23 m/pixel. Other findings and initial discussions will be presented during the virtual talk.

Acknowledgements: This work is partly supported by the Centre National d' Études Spatiales. We gratefully acknowledge funding from the Italian Space Agency (ASI) under ASI-INAF agreement2017-47-H.0. The authors acknowledge the use of MESSENGER data.
Investigating the primacy of B-matrix EDA flow dependence within the Copernicus Regional Re-Analysis (CERRA)
Authors: El-Said Adam , Brousseau Pierre , Ridal Martin
Published: March 2021

The new Copernicus European Regional Re-Analysis (CERRA) is a 5.5km reanalysis, starting in 1984 and ending “near-real-time”, 2021. The reanalysis was delivered using the ALADIN model under the HARMONIE scripting garb. The upper-air is analysed using a 3DVAR technique cycled 3-hourly, while the surface analysis is achieved through a conventional OI technique (MESCAN). Analyses produced by CERRA at 5.5km are assisted through an accompanying 10-member Ensemble Data Assimilation (EDA) system with 11km horizontal resolution cycled 6-hourly. The EDA system is used mainly for serially updated background error covariance estimation (B-matrix) used in the deterministic upper-air 3DVAR minimisation to produce the upper-air analysis.

The B-matrix comprises 2 principal EDA-derived components. The first component is estimated from same-resolution (5.5km) forecast differences, run in the winter and the summer periods, to represent seasonal climatology. This component also varies in time, such that a linearly appropriated proportion of summer or winter differences is taken, based on the current time of year of the reanalysis. The second component comes from the lower-resolution (11km) set of forecast differences, which represents ‘errors of the day’. This second component is a 2.5 day moving average ingested into a new B-matrix every 2 days. The B-matrix is thus comprised of 80% forecast differences coming from the first component and 20% coming from the second component. 

We show results from our study on the primacy of varying the weighting on the 2 components of forecast differences mentioned above, and how it has the potential, given a suitable observation network, to provide better B-matrix statistics.
The key role of aerosol-radiation-interactions on cloud formation and precipitation in the Amazon
Authors: Liu Lixia , Cheng Yafang , Wang Siwen , Wei Chao , Pöhlker Mira , Pöhlker Christopher , Artaxo Paulo , Shrivastava Manish , Andreae Meinrat , Pöschl Ulrich , Su Hang
Published: March 2021

Biomass burning (BB) aerosols can influence regional and global climate through interactions with radiation, clouds, and precipitation. Here, we investigate the impact of BB aerosols on the energy balance and hydrological cycle over the Amazon Basin during the dry season. We performed WRF-Chem simulations for a range of different BB emission scenarios to explore and characterize nonlinear effects and individual contributions from aerosol–radiation interactions (ARIs) and aerosol–cloud interactions (ACIs). For scenarios representing the lower and upper limits of BB emission estimates for recent years (2002–2016), we obtained total regional BB aerosol radiative forcings of -0.2 and 1.5Wm-2, respectively, showing that the influence of BB aerosols on the regional energy balance can range from modest cooling to strong warming. We find that ACIs dominate at low BB emission rates and low aerosol optical depth (AOD), leading to an increased cloud liquid water path (LWP) and negative radiative forcing, whereas ARIs dominate at high BB emission rates and high AOD, leading to a reduction of LWP and positive radiative forcing. In all scenarios, BB aerosols led to a decrease in the frequency of occurrence and rate of precipitation, caused primarily by ACI effects at low aerosol loading and by ARI effects at high aerosol loading. Overall, our results show that ACIs tend to saturate at high aerosol loading, whereas the strength of ARIs continues to increase and plays a more important role in highly polluted episodes and regions. This should hold not only for BB aerosols over the Amazon, but also for other light-absorbing aerosols such as fossil fuel combustion aerosols in industrialized and densely populated areas. The importance of ARIs at high aerosol loading highlights the need for accurately characterizing aerosol optical properties in the investigation of aerosol effects on clouds, precipitation, and climate.
Spending Less Than 100$ on Real-Time Sewer Flow Measurements
Authors: Meier Robert , Tscheikner-Gratl Franz , Makropoulos Christos
Published: March 2021

As more and more computational power becomes available at increasingly affordable prices, the last years have seen a veritable explosion in the number of sensors and interconnected devices. This evolution is well known and often referred to as the 4th industrial revolution, or the IoT. The water sector, albeit often conservative in adopting new technologies, will profit from this continued digitalisation in various ways.

In this work we focus on the vision of covering entire sewer systems by tightly knit sensor networks which can process the generated amount of data simultaneously. Given the large number of sensors required, the only possibility to implement such a network is keeping costs as low as possible for the individual devices or use already existing sensors in multiple ways (e.g., traffic cameras helping in flood detection).

Using hardware of the Raspberry Pi ecosystem, currently retailing at less than 100$, we collected continuous video footage of an artificial open channel in a laboratory setting and used a deep neural network to extract the water level and surface velocity. The measurement accuracy of the prediction algorithm was then compared to conventional flow sensors to assess the practicality of this approach. Preliminary results in a laboratory setting indicate a sufficient prediction accuracy of the water level for engineering uses but further work is needed to verify this in a long-term field study.

After this initial stage, deploying the sensor in a real-world setting as part of the B-WaterSmart project is planned. Apart from verifying the results under real conditions, we will then be able to assess the long-term behaviour of this approach. This includes an evaluation of the maintenance effort. As the sensor is not in direct contact with the sewage, the typical need for frequent cleaning should be greatly reduced, which in turn is expected to further lower the costs.

We argue that if such a cheap sensor can ultimately be established as a viable alternative to more conventional flow sensors, the vision of sewer networks covered entirely by sensors, could become more attainable in practice.
3D Gravity modeling of the volcanic island of Surtsey, Iceland
Authors: sayyadi sara , T. Gudmundsson Magnús , Högnadóttir Thórdís , White James , M.C. Belart Joaquín , D. Jackson Marie
Published: March 2021

The formation of the oceanic island Surtsey in the shallow ocean off the south coast of Iceland in 1963-1967 remains one of the best-studied examples of basaltic emergent volcanism to date. The island was built by both explosive, phreatomagmatic phases and by effusive activity forming lava shields covering parts of the explosively formed tuff cones.  Constraints on the subsurface structure of Surtsey achieved mainly based on the documented evolution during eruption and from drill cores in 1979 and in the ICDP-supported SUSTAIN drilling expedition in 2017(an inclined hole, directed 35° from the vertical). The 2017 drilling confirmed the existence of a diatreme, cut into the sedimentary pre-eruption seafloor (Jackson et al., 2019). 

We use 3D-gravity modeling, constrained by the stratigraphy from the drillholes to study the structure of the island and the underlying diatreme.  Detailed gravity data were obtained on Surtsey in July 2014 with a gravity station spacing of ~100 m. Density measurements for the seafloor sedimentary and tephra samples of the surface were carried out using the ASTM1 protocol. By comparing the results with specific gravity measurements of cores from drillhole in 2017, a density contrast of about 200 kg m-3 was found between the lapilli tuffs of the diatreme and the seafloor sediments.  Our approach is to divide the island into four main units of distinct density: (1) tuffs above sea level, (2) tuffs below sea level, (3) lavas above sea level, and (4) a lava delta below sea level, composed of breccias over which the lava advanced during the effusive eruption.  The boundaries between the bodies are defined from the eruption history and mapping done during the eruption, aided by the drill cores. 

A complete Bouguer anomaly map is obtained by calculating a total terrain correction by applying the Nagy formula to dense DEMs (5 m spacing out to 1.2 km from station, 200 m spacing between 1.2 km and 50 km) of both island topography and ocean bathymetry.  Through the application of both forward and inverse modeling, using the GM-SYS 3D software, the results provide a 3-D model of the island itself, as well as constraints on diatreme shape and depth.
Novel use of climate model data for deriving future flood risk underwriting and risk selection data – A Hong Kong Case Study
Authors: Alexandre Rebecca , Willis Iain
Published: March 2021

The re/insurance, banking and mortgage sectors play an essential role in facilitating economic stability. As climate change-related financial risks increase, there has long been a need for tools that contribute to the global industry’s current and future flood risk resiliency. Recognising this gap, JBA Risk Management has pioneered use of climate model data for rapidly deriving future flood risk metrics to support risk-reflective pricing strategies and mortgage analysis for Hong Kong.

JBA’s established method uses daily temporal resolution precipitation and surface air temperature Regional Climate Model (RCM) data from the Earth System Grid Federation’s CORDEX experiment. Historical and future period RCM data were processed for Representative Concentration Pathways (RCPs) 2.6 and 8.6, and time horizons 2046-2050 and 2070-2080 and used to develop fluvial and pluvial hydrological model change factors for Hong Kong. These change factors were applied to baseline fluvial and pluvial flood depths and extents, extracted from JBA’s high resolution 30m Hong Kong Flood Map. From these, potential changes in flood event frequency and severity for each RCP and time horizon combination were estimated.

The unique flood frequency and severity profiles for each flood type were then analysed with customised vulnerability functions, linking water depth to expected damage over time for residential and commercial building risks. This resulted in quantitative fluvial and pluvial flood risk metrics for Hong Kong.

Newly released, Hong Kong Climate Change Pricing Data is already in use by financial institutions. When combined with property total sum insured data, this dataset provides the annualised cost of flood damage for a range of future climate scenarios. For the first time, our industry has a tool to quantify baseline and future flood risk and set risk-reflective pricing for Hong Kong portfolios.

JBA’s method is adaptable for global use and underwriting tools are already available for the UK and Australia with the aim of improving future financial flood risk mitigation and management. This presentation will outline the method, provide a comparison of baseline and climate change flood impacts for Hong Kong and discuss the wider implications for our scientific and financial industries.
On the generation of plate-like surface tectonics in whole-mantle convection models employing composite rheology 
Authors: Arnould Maelis , Rolf Tobias , Manjón-Cabeza Córdoba Antonio
Published: March 2021

Earth’s lithospheric behavior is tied to the properties and dynamics of mantle flow. In particular, upper mantle rheology controls the coupling between the lithosphere and the asthenosphere, and therefore partly dictates Earth’s tectonic behavior. It is thus important to gain insight into how Earth’s upper mantle deforms in order to understand the evolution of plate tectonics. The presence of seismic anisotropy in the uppermost mantle suggests the existence of mineral lattice-preferred orientation (LPO) caused by the asthenospheric flow. Together with laboratory experiments of mantle rock deformation, this indicates that Earth’s uppermost mantle can deform in a non-Newtonian way, through dislocation creep. Although such a deformation mechanism can significantly impact both mantle flow and the surface tectonic behavior, most numerical studies of whole-mantle convection use a viscoplastic rheology involving diffusion creep as the only deformation mechanism in the mantle.

Here, we investigate the effects of using a composite rheology (with both diffusion and dislocation creep) on the surface tectonic behavior in 2D-cartesian whole-mantle convection models that self-consistently generate plate-like tectonics. We vary the proportion of dislocation creep in the mantle by imposing different temperature- and depth-dependent transitional stresses between diffusion and dislocation creep. Using different yield stresses, we investigate how the amount of dislocation creep affects the planform of convection and promotes surface plate-like or stagnant-lid behavior. In particular, we show that for a given yield stress promoting plate-like behavior in diffusion-creep-only models, a progressive increase in the amount of dislocation creep affects the shape and dynamics of slabs, eventually leading to stagnant-lid convection. We discuss the spatio-temporal distribution of dislocation creep in the mantle in light of the observed geometry of slabs and the spatial distribution of seismic anisotropy in Earth’s upper-mantle.
Glacier Changes in Iceland From ∼1890 to 2019
Authors: Aðalgeirsdóttir Guðfinna , Magnússon Eyjólfur , Pálsson Finnur , Thorsteinsson Thorsteinn , Belart Joaquín , Jóhannesson Tómas , Hannesdóttir Hrafnhildur , Sigurðsson Oddur , Gunnarsson Andri , Einarsson Bergur , Berthier Etienne , Schmidt Louise , Haraldsson Hannes , Björnsson Helgi
Published: March 2021

The volume of glaciers in Iceland (∼3,400 km3 in 2019) corresponds to about 9 mm of potential global sea level rise. In this study, observations from 98.7% of glacier covered areas in Iceland (in 2019) are used to construct a record of mass change of Icelandic glaciers since the end of the 19th century i.e. the end of the Little Ice Age (LIA) in Iceland. Glaciological (in situ) mass-balance measurements have been conducted on Vatnajökull, Langjökull, and Hofsjökull since the glaciological years 1991/92, 1996/97, and 1987/88, respectively. The combined record shows a total mass change of −540 ± 130 Gt (−4.2 ± 1.0 Gt a−1 on average) during the study period (1890/91 to 2018/19). This mass loss corresponds to 1.50 ± 0.36 mm sea level equivalent or 16 ± 4% of mass stored in Icelandic glaciers around 1890. Almost half of the total mass change occurred in 1994/95 to 2018/19, or −240 ± 20 Gt (−9.6 ± 0.8 Gt a−1 on average), with most rapid loss in 1994/95 to 2009/10 (mass change rate −11.6 ± 0.8 Gt a−1). During the relatively warm period 1930/31–1949/50, mass loss rates were probably close to those observed since 1994, and in the colder period 1980/81–1993/94, the glaciers gained mass at a rate of 1.5 ± 1.0 Gt a−1. For other periods of this study, the glaciers were either close to equilibrium or experienced mild loss rates. Comparison of our results with WGMS time series (Zemp et al., 2019) shows that the interannual variability is generally well captured by both data sets, but some details are not; for example, the large ice melt due to the Gjálp eruption in October 1996 and the non-surface mass balance are not included by WGMS data set. Our time seris is within the large uncertainty range of the GRACE record (Wouters et al., 2019) that has some years (e.g., 2006/07 and 2010/11) with more negative mass change, and others (e.g., 2005/06, 2011/12, and 2013/14) with less negative mass change than our estimates.
Advances in the HadCRUT5 record of global near-surface temperatures since 1850
Authors: Morice Colin , Kennedy John , Rayner Nick , Winn Jonathan , Hogan Emma , Killick Rachel , Dunn Robert , Osborn Tim , Jones Phil , Simpson Ian
Published: March 2021

The new HadCRUT5 data set combines meteorological station air temperature records with sea-surface temperature measurements in a data set of near-surface temperature anomalies from the year 1850 to present. Major developments in HadCRUT5 include: updates to underpinning observation data holdings; use of an updated assessment of the impacts of changing marine measurement methods; and adoption of a statistical gridding method to extend estimates into sparsely observed regions of the globe, such as the Arctic. The data are presented as a 200-member ensemble that spans the assessed uncertainty associated with adjustments for long-term observational biases, observing platform measurement errors and the interaction of observational sampling with gridding methods. The impacts of methodological changes in HadCRUT5 on diagnostics of the global climate will be discussed and compared to results derived from other state-of-the-art global data sets.
High-speed tensile fractures in granite and gneiss: an experimental study
Authors: Jacob Beno J , Misra Santanu , Parameswaran Venkitanarayanan , Mandal Nibir
Published: March 2021

Tensile fractures are ubiquitous in impact structures formed because of high strain rate deformations of the earth’s crust. At regions far from the point of meteorite impact, intense rupturing, fragmentation, and pulverisation are an implication of pressure waves limiting at the tensile strength of the host rock with little influence of shock deformation or shear failure. The branching and anastomosing of the fractures are controlled by the local stress state and anisotropy. Thus, a network of infilled fractures or impact breccia dikes is a common feature in the subsurface of impact sites.

We have investigated the failure processes under high strain rates responsible for the formation of Mode-I breccia dikes, at the laboratory scale. The control of planar fabric structures in the development of anastomosing tensile fracture networks was studied through high-strain-rate Brazilian disc tests on gneiss (foliated) and granite (isotropic) samples. A Split Hopkinson Pressure Bar, equipped with high-speed photography (~105 fps), was employed in the study. The gneissic foliation in the gneiss samples were oriented at θ = 0, 45 and 90° to the compression direction. The strength of granite lies between 24 and 26 MPa, and the gneisses failed in the range of 29-37MPa at about 70-90 μs. The fracture network formation was seen in the time series images. There is a stark disparity in the nature of failure of granite from gneiss and the geometry of clasts formed in each rock type. While granite samples fail with pulverised clasts localised along a single fracture spanning the diameter of the sample along the compression direction, the gneisses further developed a network of secondary fractures forming large elongate clasts. Preferential orientation of secondary crack growth in relation to the foliation is strongly influenced by θ in gneiss samples. The aspect ratio of the pulverised clasts (size < 10mm) formed in granite was about 1:2, whereas the gneisses produced larger clasts. The clasts in gneisses had an aspect ratio of 1:4 for θ = 45 and 90º, and 1:5 for θ = 0º.

The branching and anastomosing nature of fractures is similar in fracture networks observed from the field and in the experiments, thus providing an insight into the formation of high-speed impact breccia dikes in isotropic and foliated rocks. Our experiments demonstrate that monomict breccia dikes may by formed in situ inclusive of clasts, rather than by infilling in previously formed tensile fractures.
A description of the COS budget inferred by inverse modelling
Authors: Remaud Marine , Abadie Camille , Belviso Sauveur , Berchet Antoine , Chevallier Frédéric , Maignan Fabienne , Peylin Philippe
Published: March 2021

Carbonyle Sulphide, a trace gas exhibiting a striking similarity with CO2 in the biochemical diffusion path of leaves, has been recognized to be a promising surrogate of CO2 for estimating carbon storage in the terrestrial vegetation. Based on the similarity between COS and CO2, an empirical linear model relating both gas concentrations provides constraints on the estimation of the Gross Primary Productivity (GPP), the amount of carbon dioxide that is absorbed by ecosystems. However, large uncertainties on the other components of its atmospheric budget prevent us from directly relating the atmospheric COS measurements to the the GPP at global scale. The largest uncertainty arises from the closure of its atmospheric budget, with a source component missing. We explore here the benefit of assimilating both COS and CO2 measurements into the LMDz atmospheric transport model to gain insight on the COS budget. We develop an analytic inverse system which optimized the biospheric fluxes within the 14 Plant functional Type (PFTs) as defined in the ORCHIDEE land surface model. The vegetation uptake of COS is parameterized as a linear function of GPP and of the leaf relative uptake (LRU), which is the ratio of COS to CO2 deposition velocities in plants. A possible scenario leads to a global biospheric sink between 800-900 GgS/y, with a higher GPP in the high latitudes and higher total oceanic emissions between 400 and 600 GgS/y over the tropics. The COS inter-hemispheric gradient is in better agreement with HIPPO independent aircraft measurements. The comparison against NOAA COS airborne profiles and Solar Induced Fluorescence shed light on a too strong GPP in spring in ORCHIDEE in northern America,  leaving room for improvements. We also show that uncertainty in the location of hot spots in the prior anthropogenic inventory limits the use of atmospheric COS measurements in inverse modeling.
A new insight to daily precipitation estimation using different interpolation methods
Authors: Modiri Ehsan , Bárdossy András
Published: March 2021

The gridded interpolated daily precipitation data has a vast application in hydrometeorology. The fine resolution gridded precipitation gained terrestrial measurements is a tool to evaluate satellite, reanalysis, and radar-based gridded products. In this study, the daily time series of 1561 rain gauges over Iran for the period of 2003-20010 is used to compute 1 km * 1 km interpolated maps. The nearest neighborhood, Inverse Distance Weighting (IDW), Ordinary Kriging (OK), External Drift Kriging (EDK), and Quantile Kriging (QK) interpolation methods are applied to compare their performance. Due to the large size of the interpolated region and different climates, six clusters for estimating the variogram function are determined. The distinct interpolation methods lead to different daily precipitation estimates, however in the same spatial resolution, OK is showed slightly better results with the mean RMSE and correlation equal to 2.355 and 0.766, respectively. Also, the spatially aggregated gridded maps illustrated that the interpolation methods only play a significant role in the fine resolutions than the coarser ones.
PM-induced oxidative potential: Two years measurements and source apportionment, on a seasonal basis, in Athens, Greece
Authors: Paraskevopoulou Despina , Grivas George , Bougiatioti Aikaterini , Stavroulas Iasonas , Tsagkaraki Maria , Liakakou Eleni , Nenes Athanasios , Mihalopoulos Nikolaos
Published: March 2021

PM-induced oxidative stress has been proposed as a primary mechanism in cardiovascular and respiratory diseases, as well as premature death. Consequently, a variety of in vitro and in vivo assays have been developed in order to estimate the oxidative potential of ambient PM (Particulate matter), including the acellular assay of DTT (dithiothreitol), which is used in the present study. Athens, Greece is representative of air masses arriving over Eastern Mediterranean, highlighting the effect of long-range aerosol transportation and intense local emissions, such as wood burning for domestic heating purposes during the coldest period of the year. 

Most studies of aerosol oxidative potential (OP) cover a short period of time, while in this study the OP was measured during two years (2016-2018), in parallel with other PM chemical components, in order to identify the sources of aerosol OP. Fine aerosol fraction (PM2.5, diameter < 2.5 μm) was collected, using quartz fibre filters and low-volume samplers, in the centre of Athens city.

An innovative semi-automated system was used for the determination of PM water soluble oxidative potential, following the approach of Fang et al. (2015). Concurrent estimation of inorganic and organic aerosol components’ concentrations was accomplished through Ion chromatography, Aerosol Chemical Speciation Monitor, Aethalometer and OC/EC analyser. Additionally, the samples were further analyzed by Inductively coupled plasma mass spectrometry for major and trace water-soluble metal concentrations. Principal component analysis and Positive Matrix Factorization are applied to identify the sources of fine aerosol at the studied site in Athens, and determine the contribution of each source to aerosol OP, on a seasonal basis

As expected, OP presented higher values during wintertime, when wood burning appeared to be the dominant source of aerosol. These results agree with previous studies, indicating that the combustion is the major source of water-soluble OP, both as primary and secondary emission (Paraskevopulou et al. 2019). Whereas during summer, the current study reveals, for the first time, the significant impact of water-soluble metals in aerosol toxicity during the warmest period of the year, over the studied area. The aforementioned combination of various PM chemical parameters leads to a scarce identification of various aerosol OP sources on a temporal basis, in the area of Eastern Mediterranean.
Urban weather generation: the intercomparison of three emerging models
Authors: Gal Csilla
Published: March 2021

Cities modify the background climate through the surface-atmosphere interaction. This modification is function of urban design features, such as the configuration of buildings and the amount of vegetation. Compared to the undisturbed climate of the region, the climate of cities is characterized by higher temperature and lower wind speed. This modification is especially pronounce in dense urban areas. The climate modification of cities is not static, but varies in space and time. The spatial variations are governed by land use and built form differences, as well as by the presence or absence of green and blue infrastructures. Due to the spatial complexity of cities and the general lack of urban weather station networks in most places, the amount of available urban weather data is limited. As a consequence, planners, engineers and public health professionals can only approximate the climate impact of built environments in their respective fields.

Over the past years, several numerical simulation models have emerged that are able to model the influence of built areas on the atmosphere at the local scale and thus, deliver urban weather data for an area of interest. The aim of this study is to assess the performance of three numerical models with an ability to predict site-specific urban air temperature. The evaluated models are the Urban Weather Generator (UWG), the Vertical City Weather Generator (VCWG) and the Surface Urban Energy and Water Balance Scheme (SUEWS). Although the models differ in their scopes, modeling approaches and applications, they all derive the urban weather data from rural observations considering the land use and built form characteristics of the site.

The models are evaluated against air temperature measurements from the dense, 13th District of Budapest (Hungary). The field measurement utilized simple air temperature and relative humidity loggers placed in non-aspirated solar radiation screens at four shaded sites. The two week measurement period encompassed a five-day-long anticyclonic period with clear sky and low wind speed. Preliminary results indicate a good general agreement between modeled and observed values with root mean square error below or at 2ºC and index of agreement between 0.92-0.96. During the anticyclonic period most models slightly overestimate the daily maximum and underestimated the daily minimum urban air temperature.
Sahel droughts induced by large volcanic eruptions over the last millennium in IPSL-CM6A-LR model
Authors: Villamayor Julián , Khodri Myriam
Published: March 2021

The Sahel region is extremely sensible to alterations in its characteristic precipitation regime, associated with the West African Monsoon (WAM). In fact, the WAM presents strong variability at several timescales which has focused the attention of many works that mainly attribute such changes to variations in the sea surface temperature, the emerging increase of greenhouse gases concentration and to alterations in land use. However, the impact of large volcanic eruptions has been just tentatively addressed. This work aims at shedding more light on the influence of large volcanic eruptions on Sahel rainfall relying on past1000 simulations, covering the last millennium, of the IPSL-CM6A-LR model. The results show the mechanisms involved and the differences between tropical and high-latitude eruptions.