bluuebunny/crossref_metadata_2025 huggingface dataset:
AGI's Framework on Addressing Equity in the Geoscience Societies and the Challenge of Defining Success
Authors: Keane Christopher , Sullivan Susan , Gonzales Leila
Published: March 2021

The American Geosciences Institute in cooperation with its member societies has developed the Framework for Addressing Racial and Ethnic Equity in Geosciences Professional Societies.  The geoscience societies are a pivotal area to influence the culture of the geosciences, and in response to the events of June 2020, many societies determined they needed to directly act on the issue of equity in the geosciences. Being birthed from a federation of US-centric organizations, the Framework has clear US-aligned approaches and boundaries.  However, the baseline proposed actions are fundamentally universal and meet the goal of the authoring committee to provide a framework from which we hope geoscience organizations of all types would use it to craft their own specific action plan and policies.   A critical component of this framework for the committee was to ensure definable actions were included.   Some of these suggested actions and their intended extensions will be discussed.  Additionally, ongoing conversations among the societies, with the US National Academy of Sciences Board on Earth Science and Resources, and other science organizations have begun to examine what the path forward looks like.   One area that AGI particularly is concerned about is the process of measuring progress.   Understanding and recognizing the impacts of efforts like this is critical to ensure agile responses for success.   But with AGI's intimate knowledge of much of the U.S. federal data, some of the ambiguities and definitional challenges within the US system complicates the ability to directly measure progress and for which further discussion of what success looks like is critically needed.  
Validation of Sentinel-5p TROPOMI cloud data with ground-based Cloudnet and other satellite data products
Authors: Compernolle Steven , Argyrouli Athina , Lutz Ronny , Sneep Maarten , Lambert Jean-Christopher , Fjaeraa Ann Mari , Granville José , Hubert Daan , Keppens Arno , Loyola Diego , O'Connor Ewan , Rasson Olivier , Romahn Fabian , Stammes Piet , Verhoelst Tijl , Wang Ping
Published: March 2021

Space-born atmospheric composition measurements, like those from Sentinel-5p TROPOMI, are strongly affected by the presence of clouds. Dedicated cloud data products, typically retrieved with the same sensor, are therefore an important tool for the provider of atmospheric trace gas retrievals. Cloud products are used for filtering and modification of the modelled radiative transfer.

In this work, we assess the quality of the cloud data derived from Copernicus Sentinel-5 Precursor TROPOMI radiance measurements. Three cloud products are considered: (i) L2_CLOUD OCRA/ROCINN CAL (Optical Cloud Recognition Algorithm/Retrieval of Cloud Information using Neural Networks; Clouds-As-Layers), (ii) L2_CLOUD OCRA/ROCINN CRB (same; Clouds-as Reflecting Boundaries), and (iii) the S5p support product FRESCO-S (Fast Retrieval Scheme for Clouds from Oxygen absorption bands for Sentinel). These cloud products are used in the retrieval of several S5p trace gas products (e.g., ozone columns and profile, total and tropospheric nitrogen dioxide, sulfur dioxide, formaldehyde). The quality assessment of these cloud products is carried out within the framework of ESA’s Sentinel-5p Mission Performance Centre (MPC) with support from AO validation projects focusing on the respective atmospheric gases.

Cloud height data from the three S5p cloud products is compared to radar/lidar based cloud profile information from the ground-based networks CLOUDNET and ARM. The cloud height from S5p CLOUD CRB and S5p FRESCO are on average 0.6 km below the cloud mid-height of CLOUDNET measurements, and the cloud top height from S5p CLOUD CAL is on average 1 km below CLOUDNET’s cloud top height. However, the comparison is different for low and high clouds, with S5p CLOUD CAL cloud top height being only 0.3 km below CLOUDNET’s for low clouds.  The radiometric cloud fraction and cloud (top) height are compared to those of other satellite cloud products like Aura OMI O2-O2. While the latitudinal variation is often similar, offsets are encountered.

Recently, major S5p cloud product upgrades were released for S5p OCRA/ROCINN (July 2020) and for S5p FRESCO (December 2020), leading to a decrease of the ROCINN CRB cloud height and an increase of the FRESCO cloud height on average. Moreover, a major change in the ROCINN surface albedo treatment leads to a clear improvement of the comparison with CLOUDNET at the complicated sea/land/ice/snow site Ny-Alesund.
Uncertainties in biomass burning emission estimates and their impact on air pollution model predictions over Africa
Authors: Bouarar Idir , Heil Angelika , Deroubaix Adrien , Visser Auke , Boersma Folkert , Brasseur Guy
Published: March 2021

Africa is the biggest continental source of biomass burning (BB) emissions. The large fluxes of chemical pollutants and aerosol emitted during intense BB events can strongly alter tropospheric chemistry and cloud dynamics and can result in widespread air pollution. Available BB emission inventories differ in terms of satellite sensor data and assumptions and methodologies used to estimate emission fluxes, and show substantial differences in emission totals and spatial and temporal patterns. The omission of small fires (<100 ha) by most satellite products is one key factor on the accuracy of the emission inventories.

The ESA Fire_CCI project has released the first burned area product for Africa from 20 m Sentinel satellite information (FireCCISFD11). Here we present new BB emission estimates for Africa based on FireCCISFD11. By resolving small fires, this inventory (Fire_CCI) yields 60 to 110% higher burning rates in 2016 than the MODIS-based products such as GFED4s, GFED4, MCD64A1 Collection 6, FireCCI51 and FINN. We perform WRF-Chem model simulation with three BB emission inventories (FINN, GFED4s and Fire_CCI) for summer 2016 corresponding with the DACCIWA aircraft campaign, which took place in June-July 2016 over Africa. We investigate the impact of uncertainties in BB emission estimates on air pollution model predictions using measurements of chemical species and aerosols from DACCIWA, NO2 and CO data from OMI and MOPITT satellites, respectively, and ground-based AOD observations from the Aeronet network. We furthermore assess the ability of the model in terms of the representation of transport of BB air masses and of the representation of chemical composition in such plumes.
Extreme gust atlas over South Africa
Authors: Larsén Xiaoli , Kruger Andries , Floors Rogier , Cavar Dalibor , Hahmann Andrea
Published: March 2021

An atlas of the 50-year gust wind at a resolution of 3 s is calculated over South Africa, at a spatial resolution of 3.3 km at several heights, including 10 m and 60 m where measurements are available.

In developing the atlas, first, 30-year wind climate (1990 - 2019) is simulated using the Weather Research and Forecasting (WRF) model. The WRF model was initialized and forced with the ERA5 data, with three nested domains and the innermost one, covering the whole country, has a spatial resolution of 3.3 km. The model outputs include the wind time series at several heights (50 m, 100 m and 200 m) every 30 minutes. The 50-year 30-min winds at several heights are then obtained by application of a suitable extreme value distribution. Afterwards, the Kaimal turbulence model is applied, in connection with an assumption of Gaussian process for the time series in the time scale 30 min to 3 s, to obtain the corresponding 3 s gust value to the 30-min values of the 50-year winds.

There is a prevalence of a variety of strong wind events in South Africa, including mid-latitude cyclones, fronts and thunderstorms. The different physical mechanisms have different levels of challenges to the simple modeling approaches applied above. For more than 100 measurement stations, the 50-year gust values have also been calculated, mostly at 10 m, some at 60 m. They are used to validate the modeled values and identify regions and areas where our meso-to-turbulence modeling needs improvement or adjustment to eventually produce a verified extreme gust atlas.
Massive data collection in volcanic areas owing to photogrammetry-derived models: a key example from the NE Rift, Mt Etna (Italy).
Authors: De Beni Emanuela , Tibaldi Alessandro , Corti Noemi , Bonali Fabio L. , Falsaperla Susanna , Langer Horst , Neri Marco , Cantarero Massimo , Reitano Danilo , Fallati Luca
Published: March 2021

The collection of a conspicuous amount of data in volcanic areas is a key for a deeper understanding of the relationships between faulting, diking and superficial volcanic processes. A way to quickly collect huge amounts of data is to analyse photogrammetry-derived models (Digital surface models, orthomosaics and 3D models) using Unmanned Aerial Vehicles (UAVs) to collect all necessary pictures obtaining final models with a texture ground resolution up to 2-3 cm/pix.

In this work, we describe our approach to build up models of a broad area located in the NE Rift of Mt. Etna, which is affected by continuous ground deformation linked to gravity sliding of the eastern flank of the volcano and dyke injection. The area is characterized by the presence of eruptive craters and fissures, extension fractures, and normal faults, as well as by historical lava flows. The goal was to quantify the kinematics at extensional fractures and normal faults, integrating the latter with seismological data to reconstruct the stress field acting in this peculiar sector of the volcano. By the point of view of UAV surveying, the test area is challenging since it is located at an altitude ranging between 2700 and 1900 m a.s.l., and it is affected by extreme weather conditions, like a strong wind. Resulting models, in the form of DSM and orthomosaic, are characterised by a resolution of 11.86 and 2.97 cm/pix, respectively, obtained from the elaboration of 4018 photos and covering an area of 2.2 km2. Thanks to these models, we recognized the presence of 20 normal fault segments, 250 extension fractures, and 54 single eruptive fissures. Considering all the above mention data, we quantified the kinematics at extensional fractures and normal faults, obtaining an extension rate of 1.9 cm/yr for the last 406 yr.
Determination of static and time-varying Earth gravity field by quantum measurements: the MOCAST+ study
Authors: Migliaccio Federica , Reguzzoni Mirko , Batsukh Khulan , Koch Oyku
Published: March 2021

In the ongoing MOCAST+ study (funded by the Italian Space Agency), the use of an enhanced cold atom interferometer is proposed for a satellite gravity mission. The instrument consists of an interferometric gravitational gradiometer with Strontium atoms, on which an optical frequency measurement is implemented by means of an ultra-stable laser, in order to also provide time measurements. The study is investigating whether this combination can give the possibility of improving the estimation of gravity models even at low harmonic degrees with inherent advantages in the modeling of mass transport and its global variations: this would represent fundamental information, e.g. in the study of variations in the hydrological cycle and relative mass exchange between atmosphere, oceans, cryosphere and solid Earth.

The main lines of the MOCAST+ proposal are: two satellites on a polar orbit (reference altitude 342 km) at a distance of about 100 km with atomic samples on board interrogated by the same clock laser (noise of the local oscillator in common). The atom interferometer should allow to collect observations of differences of the gravitational potential (which will contribute to the estimate of the low frequencies of the Earth gravity field model) and of second derivatives of the gravitational potential along one or more orthogonal directions, which will be not necessarily the same for the two satellites

In this presentation, the mathematical model for the application of the space-wise approach to the simulated data will be described, consisting in a filter - gridding - harmonic analysis scheme that is to be repeated for several Monte Carlo samples extracted for the same simulated scenario, in order to produce a sample estimate of the error covariance matrix of the harmonic coefficients.

The data analysis based on the formulated mathematical model will be applied to both static and time-variable gravity field, performing simulations over a limited time span and extending the resulting accuracy to a longer period by covariance propagation, assuming to have other independent solutions with the same accuracy. In particular, the time-variable analysis will be mainly dedicated to assessing the accuracy in estimating the rate of change in geodynamic processes for which a linear variation in time can be reasonably assumed.

 
Seismic moduli dispersion and attenuation obtained using Digital Rock Physics
Authors: Lissa Simón , Ruf Matthias , Steeb Holger , Quintal Beatriz
Published: March 2021

Seismic waves are affected by rock properties such as porosity, permeability, grain material and by their heterogeneities as well as by the fluid properties saturating the rocks. Consequently, seismic methods are a valuable tool for the indirect characterization of rocks. For example, at the microscale, the presence of compliant pores (cracks or grain contacts) in fluid-saturated rocks can cause strong seismic attenuation and velocity dispersion. In this case, the deformation caused by a passing wave induces a fluid pressure gradient between compressed compliant pores and much less compressed pores (stiff isometric pores or cracks having a different orientation than the most compressed ones) if they are hydraulically connected. The consequent fluid pressure diffusion (FPD) dissipates seismic energy due to viscous friction in the fluid.

Digital rock physics (DRP) aims to reproduce experimental measurements using numerical simulation in models derived from high resolution rock images. We developed a DRP workflow to calculate the frequency dependent seismic moduli dispersion and attenuation in fluid-saturated models derived from micro X-Ray Computed Tomography (µXRCT) images. Filtering, segmentation and meshing procedures are applied on sub-volumes of different rock images to create 3D numerical models. We apply our workflow to calculate seismic moduli attenuation due to FPD at the microscale (squirt flow). We consider a µXRCT image of a cracked (through thermal treatment) Carrara marble sample. A detailed visualization of the fluid pressure as well as of the energy dissipation rate in the 3D model helps to understand the squirt flow attenuation process at different frequencies.
Performance of RegCM4 in Simulating Subtropical Cyclones over the Southwestern South Atlantic Ocean 
Authors: da Rocha Rosmeri , de Jesus Eduardo , Reboita Michelle , Crespo Natália , Gozzo Luiz
Published: March 2021

Subtropical cyclones (SCs) climatology is evaluated in three simulations of Regional Climate Modeling version 4 (RegCM4) and in its global climate models (GCMs) drivers (HadGEM2-ES, MPI-ESM-MR and GFDL-ESM2M) over the South America domain. Three algorithms are applied to identify the SCs: the first tracks all cyclones, the second computes the thermal structure of the cyclones based on the Cyclone Phase Space (CPS) methodology, and the third automatically selects only the cyclones with subtropical features. After that, two ensembles were performed (RegCM4 and GCMs) and their climatologies are validated through comparisons with ERA-Interim reanalysis for the period 1979-2005. Over the southwestern South Atlantic Ocean, the annual average and standard deviation of SCs are 8.0± 2.5, 7.6± 2.3 and 7.2± 3.0, respectively, in ERA-Interim, RegCM4 and GCMs. Although both ensembles have a good performance in simulating the climatology of SCs, RegCM4 over perform the GCMs showing a better skill in representing both the annual mean and the interannual variability measured by the standard deviation. Moreover, RegCM4 simulates the spatial pattern of the cyclogenesis density closer to ERA-Interim than GCMs, which is another added value of the regional downscaling. SCs represent a small fraction of all cyclones over the region, which is 4.1% in ERA-Interim and GCMs and 3.5% in RegCM4. The relative importance of SCs to the total of cyclones increased to ~40% in the region near the southeast coast of Brazil. In terms of seasonal mean, simulations are able to capture the observed pattern that has the austral summer as the most cyclogenetic season. 
Re-thinking noise-induced tipping
Authors: Newman Julian , Ashwin Peter
Published: March 2021

When modelling potential tipping elements of the earth system, one conventionally distinguishes "bifurcation-induced" and "noise-induced" tipping. The former occurs when an internal system parameter slowly crosses a critical threshold and external noise is negligible. The latter arises from forcing by noise well before a critical threshold for the internal dynamics is reached. The former comes with early warning signals, due to "critical slowing down" in the internal dynamics; but the latter occurs randomly without warning. However, these descriptions typically assume that the noise is Gaussian white noise, which arises as a limit of fast-timescale chaotic driving. We will instead consider, through a simple discrete-time prototype, finite-timescale bounded chaotic driving; this is a more suitable description of the subgrid forcing of turbulent geophysical fluid dynamics than uncorrelated noise. We will see that the phenomenon previously known as "noise-induced tipping" now corresponds to a deterministic bifurcation-induced tipping of the joint dynamics of the tipping element and the driving. Although "critical slowing down" does not occur in this bifurcation, early warning and near-exact prediction of the tipping event may still be possible. We also discuss the phenomenon of "noise-induced" prevention or delay of a tipping event, which cannot occur under conventional memoryless noise.
Late Accretion and the Origin of Water on Terrestrial Planets in the Solar System
Authors: Gillmann Cédric , Golabek Gregor , Raymond Sean , Tackley Paul , Schonbachler Maria , Dehant Veronique , Debaille Vinciane
Published: March 2021

Terrestrial planets in the Solar system generally lack surface liquid water. Earth is at odd with this observation and with the idea of the giant Moon-forming impact that should have vaporized any pre-existing water, leaving behind a dry Earth. Given the evidence available, this means that either water was brought back later or the giant impact could not vaporize all the water.

We have looked at Venus for answers. Indeed, it is an example of an active planet that may have followed a radically different evolutionary pathway despite the similar mechanisms at work and probably comparable initial conditions. However, due to the lack of present-day plate tectonics, volatile recycling, and any surface liquid oceans, the evolution of Venus has likely been more straightforward than that of the Earth, making it easier to understand and model over its long term evolution.

Here, we investigate the long-term evolution of Venus using self-consistent numerical models of global thermochemical mantle convection coupled with both an atmospheric evolution model and a late accretion N-body delivery model. We test implications of wet and dry late accretion compositions, using present-day Venus atmosphere measurements. Atmospheric losses are only able to remove a limited amount of water over the history of the planet. We show that late accretion of wet material exceeds this sink. CO2 and N2 contributions serve as additional constraints.

Water-rich asteroids colliding with Venus and releasing their water as vapor cannot explain the composition of Venus atmosphere as we measure it today. It means that the asteroidal material that came to Venus, and thus to Earth, after the giant impact must have been dry (enstatite chondrites), therefore preventing the replenishment of the Earth in water. Because water can obviously be found on our planet today, it means that the water we are now enjoying on Earth has been there since its formation, likely buried deep in the Earth so it could survive the giant impact. This in turn suggests that suggests that planets likely formed with their near-full budget in water, and slowly lost it with time.
PalMod-II Data Management Plan: A FAIR-inspired conceptual framework for data simulation, inter-comparison, sharing and publication  
Authors: Gehlot Swati , Peters-von Gehlen Karsten , Lammert Andrea
Published: March 2021

Large scale transient climate simulations and their intercomparison with paleo data within the German initiative PalMod (www.palmod.de, currently in phase II) provides an exclusive example of applying a Data Management Plan (DMP) to conceptualise  data workflows within and outside a large multidisciplinary project. PalMod-II data products include output of three state-of-the-art climate models with various coupling complexities and spatial resolutions  simulating the climate of the past 130,000 years. Additional to the long time series of model data, a comprehensive compilation of paleo-observation data (including a model-observation-comparison toolbox, Baudouin et al, 2021 EGU-CL1.2) is envisaged for validation. 

Owing to the enormous amount of data coming from models and observations, produced and handled by different groups of scientists spread across various institutions, a dedicated DMP as a living document provides a data-workflow framework for exchange and sharing of data within and outside the PalMod community. The DMP covers the data life cycle within the project starting from its generation (data formats and standards), analysis (intercomparison with models and observations), publication (usage, licences), dissemination (standardised, via ESGF) and finally archiving after the project lifetime. As an active and continually updated document, the DMP ensures the ownership and responsibilities of data subsets of various working groups along with their data sharing/reuse regulations within the working groups in order to ensure a sustained progress towards the project goals. 

This contribution discusses the current status and challenges of the DMP for PalMod-II which covers the details of data produced within various working groups, project-wide workflow strategy for sharing and exchange of data, as well as a definition of a PalMod-II variable list for ESGF standard publication. The FAIR (Findability, Accessibility, Interoperability, and Reusability) data principles play a central role and are proposed for the entire life cycle of PalMod-II data products (model and proxy paleo data) for sharing/reuse during and after the project lifetime.
Mapping a Duck: Geological Features and Region Definitions on Comet 67P/Churyumov-Gerasimenko
Authors: Grieger Björn , Leon-Dasi Mireia , Besse Sebastien , Küppers Michael
Published: March 2021

The data from the Rosetta mission enabled the reconstruction of the shape of comet 67P/Churyumov-Gerasimenko (hereafter 67P) and the identification of the terrains and features forming its surface. The highly irregular  shape of the comet poses a challenge for the depiction of these geological features on two-dimensional maps. Standard global map projections cannot display the complete surface of 67P because different points on the surface can have the same longitude and latitude.  As a consequence, the geological maps published to date are  created on top of comet images, making them dependent on the viewing angle and image coverage and resolution.

Here, we make use of the recently published Quincuncial Adaptive Closed Kohonen (QuACK) map. It projects the complete surface of 67P unambiguously onto a square. The QuACK map is topologically equivalent to the Peirce quincuncial projection of the world, which makes it  possible to define generalized longitudes and latitudes. These can be used within any global map projection in order to obtain an  unambiguous QuACK version.

The mapping of geological features is carried out in three dimensions employing the Small Body Mapping Tool (SBMT). We use images from  the OSIRIS Narrow Angle Camera aboard Rosetta which have been projected onto the shape model of the SBMT. The three-dimensional coordinates are then projected onto two-dimensional maps, either in the QuACK map projection or in the QuACK version of  the equidistant cylindrical projection. We present individual maps for 17 of the 26 regions of 67P, mostly located in the northern  hemisphere. The new maps combine features published in previous studies with newly identified features.

We discuss the distribution of geological features and the characteristics of the regions. In order to align region boundaries with geological features, we propose two modifications of region definitions.
Tropical Cyclones in Reduced Rossby Wave Breaking Environments
Authors: Enz Bernhard , Neubauer David , Sprenger Michael , Lohmann Ulrike
Published: March 2021

Tropical cyclones are a weather phenomenon that can devastate coastlines and cause substantial harm to human life and infrastructure every year. Their seasonal prediction is an effort that has been undertaken for several decades. These predictions are generally useful and have skill. The 2013 season was predicted as above average in activity by all forecasting agencies, but was one of the least active on record. A previously proposed reason for this is the abundance of Rossby wave breaking in the north Atlantic, which dries and cools the tropics by mixing in extratropical air. While the existence of this mechanism is not disputed, other pathways linked to the interactions between tropical and extratropical air masses are suggested and evaluated in this study

The numerical model ICON is used in Limited Area Mode (~13 km horizontal resolution) to simulate the north Atlantic, using ERA5 data for the hurricane season of 2013 to prescribe initial and boundary conditions. To influence Rossby wave breaking, a set of simulations uses 30 day running mean boundary conditions in the northern part of the domain, while a reference set uses regular boundary conditions everywhere along the boundary. Though the results do not falsify the aforementioned hypothesis of the abundance of Rossby wave breaking influencing tropical cyclone activity, they suggest that other mechanisms, such as changes in steering flow, tropopause temperature and wind shear, could also be responsible for changes in tropical cyclone activity. Furthermore, the accumulated cyclone energy seems to be rather closely related to the mean latitude of the 2 potential vorticity unit contour on the 350 K isentropic surface within a small longitudinal window in the western Atlantic.
Endless journey of macroplastics in rivers: From hours to decades tracking in the Seine River
Authors: Tramoy Romain , Gasperi Johnny , Colasse Laurent , Silvestre Marie , Dubois Philippe , Tassin Bruno
Published: March 2021

Rivers are major pathways of plastics from lands into the Ocean. However, there is still a huge lack of knowledge on how riverine litter, including macroplastics, is transferred into the Ocean. Quantitative measurements of macroplastic emissions in rivers even suggest that a small fraction (0.001 to 3%) of the Mismanaged Plastic Waste (MPW) generated within a river basin finally reach the sea. Instead, macroplastics may remain within the catchment and on coastlines because of complex transport dynamics that delay the transfer of plastic debris. In order to better understand those dynamics, we performed tracking of riverine litter over time. First, hundreds of date-prints items were collected on riverbanks in the Seine estuary. The distribution of their Use-By-Dates suggest that riverine litter may remain stored on riverbanks for decades. Second, we performed real time tracking of floating and sub-floating bottles using GPS-trackers. Between March 2018 and April 2019, 39 trajectories were recorded in the estuary under tidal influence and 11 trajectories upriver, covering a wide range of hydrometeorological conditions. Results show a succession of stranding/remobilization episodes in combination with alternating upstream and downstream transport in the estuary related to tides. In the end, tracked bottles systematically stranded somewhere, for hours to weeks, from one to several times on different sites. The overall picture shows that different hydrometeorological phenomena interact with various time scales ranging from hours/days (high/low tides) to weeks/months (spring/neap tides and highest tides) and years (seasonal river flow, vegetation and geomorphological aspects). Thus, the fate of plastic debris is highly unpredictable with a chaotic-like transfer of plastic debris into the Ocean. The residence time of these debris is much longer than the transit time of water. This offers the opportunity to collect them before they get fragmented and/or reach the Sea.
Advancing open source cyberinfrastructure for collecting, processing, storing and accessing high temporal resolution residential water use data
Authors: Bastidas Pacheco Camilo J. , Horsburgh Jeffery S. , Brewer Joseph C. , Tracy Robb J. , Caraballo Juan
Published: March 2021

Collecting and managing high temporal resolution (< 1 minute) residential water use data is challenging due to cost and technical requirements associated with the volume and velocity of data collected. It is well known that this type of data has potential to expand our knowledge of residential water use, inform future water use predictions, and improve water conservation strategies. However, most studies collecting this type of data have been focused on the practical application of the data (e.g., developing and applying end use disaggregation algorithms) with much less focus on how the data were collected, retrieved, quality controlled, and managed to enable data visualization and analysis. We developed an open-source, modular, generalized cyberinfrastructure system to automate the process from data collection to analysis. The system has three main architectural components: first, the sensors and dataloggers for water use monitoring; second, the data communication, parsing and archival tools; and third, the analyses, visualization and presentations of data produced for different audiences. For the first component, we present a low-cost datalogging device, designed for installation on top of existing, analog, magnetically driven, positive displacement, residential water meters that can collect data at a user configurable time resolution interval. The second component consists of a system developed using existing open-source software technologies that manages the data collected, including services and databasing. The final element includes software tools for retrieving the data that can be integrated with advanced data analytics tools. The system was used in a single family residential water use data collection case study to test the scalability and performance of its functionalities within our design constraints. Testing with a base system configuration, our results show that the system requires approximately six minutes to process a single day of data collected at a four second temporal resolution for 500 properties. Thus, the system proved to be effective beyond the typical number of participants observed in similar studies of residential water use and would scale well beyond this even with the modest system resources we used for testing. All elements of the cyberinfrastructure developed are freely available in open source repositories for re-use.
Hydrological response of LULC and climate change in Mediterranean basin: application to the  Siliana catchment in Tunisia
Authors: EL Ghoul Imen , Sellami Haykel , Mounir Kaoutar , Khlifi Slaheddine , Vanclooster Marnik
Published: March 2021

Land use/ Land cover (LULC) and climate change are two main factors affecting watershed hydrology. In this study, combined effects of changes in climate and LULC on hydrological processes are investigated by comparing baseline period (2000-2013) to future conditions (2030-2070) using the Soil and Water Assessment Tool (SWAT) hydrological model in the Siliana catchment in Tunisia.

The LULC future scenarios are modelled using the Cellular Automata (CA)-Markov chain while climate change scenarios were derived from the regional climate models (RCMs) in the coordinated regional climate downscaling experiment (CORDEX-Europe). The (CDF) matching approach with observed precipitation and temperature records is used for bias correction. Subsequently, bias corrected climate projections and LULC future scenarios are fed in the SWAT model to assess changes in catchment hydrology based on a set of hydrological indicators (e.g. monthly discharge and total water availability). Prediction uncertainty related to changes in LULC, climate conditions and SWAT model parameter are also assessed.

A significant decrease in pasture and an increase in irrigated lands will likely shape the future LULC in comparison to the baseline conditions. However, these changes will be combined by a warmer and drier climate and hydrological conditions in the future in the Siliana catchment. By considering only changes in LULC in the reference period, there was a slight reduction in the surface runoff and total available water in the catchment. 

KEYWORDS: hydrologic response; land use change; climate change; uncertainty; Mediterranean catchment; SWAT model; CA-Markov
Growth, replacement and element diffusion in metamorphic garnet revealed by trace element mapping 
Authors: Rubatto Daniela , Pierre Lanari , Burger Marcel , Hattendorf Bodo , Schwarz Gunnar , Günther Detlef , Hermann Jörg , Bovay Thomas , Vho Alice , Piccoli Francesca
Published: March 2021

Garnet is one of the most robust and ubiquitous minerals that record element zoning during crustal metamorphism. In addition to major element distribution, zoning in trace elements can provide a wealth of information to document the changing conditions of garnet growth and modification. Trace element distribution in garnet grains was mapped in 2D in thin section with laser ablation inductively coupled plasma time of flight mass spectrometry (LA-ICP-TOFMS) and conventional LA-ICP-MS to achieve a lateral resolution of 15-5 µm and limits of detection for the heavy rare earth elements (REE) down to 0.2 µg/g (Rubatto et al. 2020).

In granulite-facies garnet, major elements show diffusional resetting, whereas trace elements still largely document the growth history. Enrichment of trace elements in the garnet mantle is attributed to the consumption of biotite (V, Cr) and the dissolution of zircon (Zr) and monazite (Y+REE) in the coexisting melt. Lu is notably enriched in the garnet mantle with implications for geochronology. The gradual zoning of Y+HREE between mantle and core is reconcilable with diffusion over ~200 µm in 10 My at temperatures of 750–800°C

In amphibolite facies garnet, Y+REE trace element zoning closely matches the growth zoning in Ca with no notable diffusive modification. Y+REE zoning is dominated by Rayleigh fractionation in the core and in the outer zones it shows annuli that mark the sporadic breakdown of accessory phases.

Garnet in eclogite facies samples that underwent fluid-rock interaction show growth zoning in major and trace elements, with local oscillations and sectors. In certain samples, the overall distribution of REE can be reconciled with diffusion-limited uptake. Where garnet displays fluid-related veinlets, visible in major elements, that cross-cut the primary growth zoning, the regular Y+REE and Cr growth zoning is not affected by the veinlets. This indicates that the veinlets did not form by a crack-seal mechanism but are rather related to a selective replacement process.

 

References

Rubatto D, Burger M, Lanari P, Hattendorf B, Schwarz G, Neff C, Keresztes Schmidt P, Hermann J, Vho A, Günther D (2020) Identification of growth mechanisms in metamorphic garnet by high-resolution trace element mapping with LA-ICP-TOFMS. Contrib Mineral Petrol 175:61 doi.org/10.1007/s00410-020-01700-5
Projections of groundwater recharge changes in the Mediterranean: Uncertainties of simulating groundwater recharge in global hydrological models
Authors: Kretschmer Daniel , Reinecke Robert , Gerner Alexander , Disse Markus
Published: March 2021

In the Mediterranean, climate change effects are projected to be particularly strong, and with them, the already prominent use of groundwater as a source for drinking water and irrigation is likely to increase. The sustainable amount of water that can be extracted from an aquifer is determined by groundwater recharge. Although important as an indicator for groundwater availability, quantification of this process is not sufficiently accurate at large scales due to feedbacks of processes and mechanisms. It is difficult to measure, and its rainfall based simulation is challenging because the absolute uncertainties of other water balance components accumulate, especially in dry areas.

Global hydrological models (GHMs) have proven to be a valuable tool to assess the impacts of climate change on the global water cycle; however, their simulation of groundwater recharge remains uncertain. In this presentation, we show results of an investigation of groundwater recharge by using an ensemble of eight GHMs and four global circulation models (GCMs). The assessment focuses on the Mediterranean for two evaluation periods 1861-2006 and 2006-2100. Of particular interest are the seasonal patterns of groundwater recharge and whether the models show similar seasonal patterns in the past and under different climate change scenarios. The Mediterranean is versatile in terms of topography and climatic conditions. Thus, the variation of groundwater recharge in both spatial and temporal terms is examined thoroughly.

Further, precipitation characteristics can have significant impacts on recharge amounts. Therefore, the correlation of the GCMs daily precipitation data with the modelled recharge is analyzed. Results show a significant variation within the ensemble. Overall, a declining trend in groundwater recharge is dominant.
Northeast Atlantic storminess in centennial reanalyses
Authors: Krueger Oliver , Feser Frauke , Kadow Christopher , Weisse Ralf
Published: March 2021

Global atmospheric reanalyses are commonly applied for the validation of climate models, diagnostic studies, and driving higher resolution numerical models with the emphasis on assessing climate variability and long-term trends. Over recent years, longer reanalyses spanning a period of more than hundred years have become available. In this study, the variability and long-term trends of storm activity is assessed over the northeast Atlantic in modern centennial reanalysis datasets, namely ERA-20cm, ERA-20c, CERA-20c, and the 20CR-reanalysis suite with 20CRv3 being the most recent one. All reanalyses, except from ERA-20cm, assimilate surface pressure observations, whereby ERA-20C and CERA-20c additionally assimilate surface winds. For the assessment, the well-established storm index of higher annual percentiles of geostrophic wind speeds derived from pressure observations at sea level over a relatively densely monitored marine area is used.

The results indicate that the examined centennial reanalyses are not able to represent long-term trends of storm activity over the northeast Atlantic, particularly in the earlier years of the period examined when compared with the geostrophic wind index based on pressure observations. Moreover, the reanalyses show inconsistent long-term behaviour when compared with each other. Only in the latter half of the 20th century, the variability of reanalysed and observed storminess time series starts to agree with each other. Additionally, 20CRv3, the most recent centennial reanalysis examined, shows markedly improved results with increased uncertainty, albeit multidecadal storminess variability does not match observed values in earlier times before about 1920.

The behaviour shown by the centennial reanalyses are likely caused by the increasing number of assimilated observations, changes in the observational databases used, and the different underlying numerical model systems. Furthermore, the results derived from the ERA-20cm reanalysis that does not assimilate any pressure or wind observations suggests that the variability and uncertainty of storminess over the northeast Atlantic is high making it difficult to determine storm activity when numerical models are not bound by observations. The results of this study imply and reconfirm previous findings that the assessment of long-term storminess trends and variability in centennial reanalyses remains a rather delicate matter, at least for the northeast Atlantic region.
Can fill-and-spill subsurface flow be represented by a moisture-dependent anisotropic permeability tensor in Richards equation-based models with coarse spatial resolution?
Authors: Xu Fei Esther , Harman Ciaran
Published: March 2021

Subsurface structural heterogeneity can route soil water through the vadose zone in complex ways that are difficult to observe or model in detail. The fill-and-spill hypothesis, which was developed to explain observations from field experiments at the hillslope scale, suggests that lateral flow at the soil-bedrock interface (or other permeability contrasts) is only activated once depressions in the microtopography of that interface become saturated and connect laterally. To reproduce this fill-and-spill phenomenon, a Richards equation-based numerical model would require a discretization of this morphology at a fine scale. A coarse representation smooths the interface eliminating the essential local storage-excess threshold behavior. However, the accuracy and abundance of field measurements rarely provide the data that would be needed to do this, and the fine discretization creates a high computational burden.

Here we explore the potential of an upscaled representation of the fill-and-spill mechanism based on parameterization of a permeability tensor with saturation-dependent anisotropy. By increasing empirical lateral hydraulic conductivity as they approach saturation, this anisotropy could reproduce how the fill-and-spill causes saturated patches at the permeability contrast to connect along preferential flow paths. Such a process representation could be incorporated into a Richards equation-based model enabling it to reproduce the fill-and-spill phenomenon even with a coarse spatial resolution.

We tested this idea using ParFlow to model virtual hillslopes with synthetic rugged internal topography. We then investigated the effective permeability tensor over an averaging volume that encloses the interface. By parameterizing the anisotropy of an interface block under changing moisture variables, we may be able to generate predictions of how the fine-scale fill-and-spill processes integrate to the hillslope and catchment scale.
Investigating Future Changes in the Spatial Characteristics of Precipitation Extremes over the United States
Authors: Rastogi Deeksha , Touma Danielle , Evans Katherine , Ashfaq Moetasim
Published: March 2021

An intensification of hydroclimate extremes in response to increase in radiative forcing has the potential to cause severe and widespread socioeconomic damages. Therefore, a comprehensive evaluation of projected changes in the characteristics of these extremes in a warming climate is necessary for emergency preparedness and planning. While the intensity and frequency of these extremes have been thoroughly investigated, the efforts on understanding their spatial characteristics are still limited. To this end, we use an ensemble of high-resolution regional climate simulations to investigate the spatial characteristics of daily-scale precipitation events across the United States, in addition to other features. The simulations cover 1966–2005 in the historical period and 2011–2050 in the future period under Representative Concentration Pathway 8.5 (RCP 8.5) scenario. The simulated ensemble compares well with observations in the historical period, and project further intensification of widespread extremes in the near future. Further, our results demonstrate that the projected changes in the characteristics of precipitation events are associated with more frequent occurrences of extreme years where contributions from intense and widespread events to the annual precipitation is unprecedently high. These findings highlight the need for more rigorous investigations of changes in the spatial characteristics of extremes to prepare for potential future changes and associated risks.
Ultrasonic velocity experiments on ice cores to complement fabric measurements
Authors: Hellmann Sebastian , Kerch Johanna , Grab Melchior , Löwe Henning , Bauder Andreas , Weikusat Ilka , Maurer Hansruedi
Published: March 2021

The ice crystal structure and in particular the crystal orientation fabrics (COF) provide valuable information about the deformation history of ice sheets and glaciers. Therefore, COF analysis has been among the standard measurement techniques for most deep ice core drilling projects in the last three decades. The analysis depends on carefully prepared thin sections of ice that are measured with cross-polarised light microscopy or electron backscattering and diffraction (EBSD). The preparation of thin sections is labour-intensive and therefore only a discrete number of samples along the ice core is usually analysed. Geophysical methods such as ultrasonic sounding along the ice core could be employed to complement the discrete fabric data by providing data to fill the gaps. A suitable method needs to be reasonably fast, ideally non-invasive and provides unambiguous information in combination with the established methods.

In our study, we demonstrate the feasibility of such ultrasonic experiments applied to an ice core to support the approved cross-polarised light microscopy method. Point-contact transducers transmitted ultrasonic waves into ice core samples from a temperate glacier. X-ray computer tomography measurements provide the required information to consider the effect of a two-phase medium (ice and air bubbles) in a porosity correction of the velocity. We determined the azimuthal variation of the seismic velocity. This variation is a result of seismic anisotropy due to the crystal orientation within the ice core volume. The measurements can be acquired within minutes and do not require an extensive preparation of ice samples.

In addition, the COF of adjacent ice core samples was measured with cross-polarised light spectroscopy. From this, we derived the elasticity tensor and finally calculated the associated seismic velocities for the same azimuth and inclination angle as for the ultrasonic experiments. We compare these two velocity profiles and discover a significant discrepancy in presence of large ice grains. However, with an increasing number of ice grains both methods provide similar results. Although the ultrasonic measurements reveal some ambiguities, these can be resolved when considering the information derived from the standard analysis.

We conclude that ultrasonic measurements along the ice core are suitable to support the established COF analysis for sufficiently small grains as found in polar cores. We recommend further exploration of the potential of the presented technique as it provides both the chance to obtain a continuous fabric profile and a direct link to large-scale seismic measurements in the vicinity of ice core drilling sites.