bluuebunny/crossref_metadata_2025 huggingface dataset:
How reliable are crowd-sourced data in hydrology? Lessons learned from a citizen science experiment
Authors: Klaus Julian , Hannah David , Chun Kwok Pan
Published: March 2021

Crowd-sourcing of hydrological data with volunteering citizen scientists has the potential to overcome severe data limitations in space and time. However, several aspects on the reliability, quality, and value of crowd-sourced data are under debate. In this contribution, we present results of a citizen science experiments involving 300 high school students in Luxembourg. The students relied on self-build rainfall collectors to sample precipitation over selected 24-hour periods covering Luxembourg at national scale (~2500 km2) and subsequently measured the amount. Following data collection and archiving, we evaluated the quality of the data by benchmarking the crowd-sourced values to data collected with a dense network of ~50 tipping buckets across the country. This was done by kriging both data sets. We found that the aerial precipitation at national scale derived from both data sort was consistent, however with a rather systematic bias between the two data sources. The bias was in the same range as the bias between tipping bucket data and average amounts from several measurements with a self-build sampler at the same location. The students’ data showed a clearly higher variance compared to the national data but was still able to resolve finer scale variations compared to the national network. We observed the highest differences between both data sets in urban settings. Here, it is not clear if the student’s data was less robust when acquired in an urban setting or if the difference arose from urban rainfall processes that were not observed by the national network, where stations are placed at open sites. With our proposed experiment and the statistical data analysis, we were able to quality control crowd-sourced precipitation data and showed that they are reliable. This increases confidence for many studies relying on similar samplers. Yet, some samples of individuals showed a rather high deviation from the kriged national network, showing that sampling with only a few citizen observers could lead to higher uncertainty in the data. While some limitations exist, we showed that data from citizens are of high quality and provide valuable information for hydrological studies.
Contribution of urbanization and climate variability on surface water depletion across USA watersheds
Authors: Ceola Serena , Palazzoli Irene
Published: March 2021

Surface water resources are extremely vulnerable to climate variability and are seriously threatened by human activities. The depletion of surface water is expected to rapidly increase due to the combination of future climate change and world population growth projections. Under this scenario, the impacts of climate and human dynamics on surface water resources represent a global issue, requiring the definition of adequate management strategies that prevent water crisis and guarantee equitable access to freshwater resources. Remote sensing provides data that allow to monitor environmental change processes, such as changes in climatic conditions, land use, and spatial allocation of human settlements and activities. Although many products describing surface water dynamics and urban growth obtained from satellite imagery are available, an integrated analysis of such geospatial information has not been performed yet. Here, we explore the driving role of the variation in key climatic variables (e.g.,  precipitation, temperature, and soil moisture) and the extent of urban areas in the depletion of surface water across the watersheds in the United States by using data derived from remote sensing images and performing a correlation analysis. From our preliminary results, we observe that there is a positive correlation between surface water loss and the level of urbanization in each basin of our study area, meaning that surface water loss increases with the extent of urban area. On the contrary, we find that the correlation between surface water loss and precipitation has a counter-intuitive trend which needs to be further examined.
Wind Turbine Noise Reduction from Seismological Data
Authors: Heuel Janis , Friederich Wolfgang
Published: March 2021

Over the last years, installations of wind turbines (WTs) increased worldwide. Owing to
negative effects on humans, WTs are often installed in areas with low population density.
Because of low anthropogenic noise, these areas are also well suited for sites of
seismological stations. As a consequence, WTs are often installed in the same areas as
seismological stations. By comparing the noise in recorded data before and after
installation of WTs, seismologists noticed a substantial worsening of station quality leading
to conflicts between the operators of WTs and earthquake services.

In this study, we compare different techniques to reduce or eliminate the disturbing signal
from WTs at seismological stations. For this purpose, we selected a seismological station
that shows a significant correlation between the power spectral density and the hourly
windspeed measurements. Usually, spectral filtering is used to suppress noise in seismic
data processing. However, this approach is not effective when noise and signal have
overlapping frequency bands which is the case for WT noise. As a first method, we applied
the continuous wavelet transform (CWT) on our data to obtain a time-scale representation.
From this representation, we estimated a noise threshold function (Langston & Mousavi,
2019) either from noise before the theoretical P-arrival (pre-noise) or using a noise signal
from the past with similar ground velocity conditions at the surrounding WTs. Therefore, we
installed low cost seismometers at the surrounding WTs to find similar signals at each WT.
From these similar signals, we obtain a noise model at the seismological station, which is
used to estimate the threshold function. As a second method, we used a denoising
autoencoder (DAE) that learns mapping functions to distinguish between noise and signal
(Zhu et al., 2019).

In our tests, the threshold function performs well when the event is visible in the raw or
spectral filtered data, but it fails when WT noise dominates and the event is hidden. In
these cases, the DAE removes the WT noise from the data. However, the DAE must be
trained with typical noise samples and high signal-to-noise ratio events to distinguish
between signal and interfering noise. Using the threshold function and pre-noise can be
applied immediately on real-time data and has a low computational cost. Using a noise
model from our prerecorded database at the seismological station does not improve the
result and it is more time consuming to find similar ground velocity conditions at the
surrounding WTs.
Persistence and variability of Earth's inter-hemispheric albedo symmetry
Authors: Jönsson Aiden , Bender Frida
Published: March 2021

Earth's albedo is observed to be symmetric about the equator on long time scales despite having an asymmetric distribution of land and aerosol sources between the northern and southern hemispheres. This is made possible by the distribution of clouds, which compensates the clear-sky albedo asymmetry almost exactly. We investigate the variability of the inter-hemispheric difference in reflected solar radiation (asymmetry) on the monthly time scale using decomposed reflected radiative fluxes in the CERES EBAF satellite data record. We find that the variations in the degree of symmetry on shorter timescales is strongly controlled by tropical and subtropical processes affecting cloud distributions. States of high asymmetry coincide with opposing phases of the El Niño-Southern Oscillation (ENSO); during El Niño (La Niña) conditions, the southern (northern) hemisphere is reflecting anomalously more than the other, perturbing the inter-hemispheric albedo symmetry. This perturbation also impacts the inter-hemispheric difference in net radiative fluxes, i.e. during states of asymmetry, the hemisphere that is reflecting less solar radiation also absorbs more energy in the net radiation balance.

We also compare the variability of the asymmetry in simulations from coupled models in Phase 6 of the Coupled Model Intercomparison Project with observations, and find that model mean asymmetry bias is primarily determined by biases in reflected radiation in the midlatitudes. Models that overestimate the variability of the asymmetry also have larger biases in reflected radiation over the tropics. Both bias and variability are generally improved in atmospheric model simulations driven with historical sea surface temperatures.
Debris Yield Modeling Application under Post-Wildfire Conditions with the Hydrologic Modeling System (HEC-HMS)
Authors: Pak Jang , Floyd Ian , Ely Paul
Published: March 2021

Predicting debris yield under post-wildfire conditions is important for hazard mitigation and flood risk planning. Current prediction efforts aim to reduce the amount and impacts of debris flows that minimizes environmental and economic impacts for communities. However, recovery efforts are difficult and costly. Debris flows and excess runoff block access roads and bridges, inhibiting emergency responses. It also effects the surrounding community's water supply and property. Therefore, having a debris flow sediment management plan is crucial. Predicting debris yield volume, estimating debris basin capabilities, and developing yield mitigation alternatives will mitigate future debris yield disasters. In previous versions of the Hydrologic Engineering Center, Hydrologic Modeling System (HEC-HMS) contains no capacity to simulate debris yield. However, the need for debris yield modeling exists throughout the Corps of Engineers, especially mountainous in arid and semi-arid regions. The HEC has added empirical models for prediction debris yield volumes under post-wildfire conditions. The goal is to develop tools within HEC-HMS that provide outputs necessary for developing debris yield mitigation strategies for managing debris yields within the burned watershed. This research discusses the addition of debris yield methods under post-wildfire situations within the watershed available in HEC-HMS 4.5. The new debris yield modeling capabilities will increase the application of HEC-HMS for debris yield modeling studies by directly computing yields from burn watersheds. Additionally, the model was coupled with the Hydrologic Engineering Center, River Analysis System (HEC-RAS) to ensure that debris yield output from HEC-HMS could be easily used as boundary conditions for predicting the hydraulic non-Newtonian debris flow runout and inundation.  The new debris yield methods use precipitation, topography, and soil burn severity information within the watershed to model debris yield. Reach and reservoir debris routing methods are being further developed, meanwhile existing sediment flow routing methods in reach and reservoir elements can be used with certain limitations.

 

Keywords: Debris Yield Prediction; Post-Wildfire; Hazard Mitigation; Hydrology Modeling System
Rainfall Spatial variability, rainfall intensity–duration (ID) thresholds, and the initiation of debris flows in the eastern Italian Alps
Authors: Francis Oliver , Tang Hui , Gregoretti Carlo , Berti Matteo , Bernard Martino , Simoni Alessandro
Published: March 2021

Runoff-generated debris flows are a significant hazard in steep mountain ranges across the world. During intense rainfall storms, runoff can rapidly form in small steep basins and mobilise large volumes of sediment triggering debris flows which can damage infrastructure and endanger lives. A common method for forecasting debris flows is deriving empirical rainfall intensity–duration (ID) thresholds from previously recorded debris flow events in a given area. However, the storms which trigger debris flows usually are short and intense with high spatial variation making an accurate recording of the conditions responsible for initiation difficult.

In this study, we investigate the impact of the spatial variability of rainfall on debris flow initiation in small, steep, and debris flow prone catchments in the eastern Italian Alps (Dolomites) using the SWEHR (Shallow Water Equation Hairsine-Rose) numerical model. The modelled catchments are monitored by multiple rain gages which we use to quantify the uncertainty of the rainfall ID thresholds due to the spatial variation of rainfall by comparing empirical and numerically modelled thresholds. We also compare simulated triggering discharges for debris flows with available field observations in the study area. This study will help to improve the quality of hazard forecasting of debris flows in mountainous regions
The formation and evolution of the electron strahl in the inner heliosphere
Authors: Jeong Seong-Yeop , Verscharen Daniel , Christian Vocks , Owen Christopher , Wicks Robert , Fazakerley Andrew
Published: March 2021

The electrons in the solar wind exhibit an interesting kinetic substructure with many important implications for the overall energetics of the plasma in the heliosphere. We are especially interested in the formation and evolution of the electron strahl, a field-aligned beam of superthermal electrons, in the heliosphere. We develop a kinetic transport equation for typical heliospheric conditions based on a Parker-spiral geometry of the magnetic field. We present the results of our theoretical model for the radial evolution of the electron velocity distribution function (VDF) in the solar wind. We study the effects of the adiabatic focusing of energetic electrons, wave-particle interactions, and Coulomb collisions through a generalized kinetic equation for the electron VDF. We compare and contrast our results with the observed effects in the electron VDFs from space missions that explore the radial evolution of electrons in the inner heliosphere such as Helios, Parker Solar Probe, and Solar Orbiter.
First Results From SPICE EUV Spectrometer on Solar Orbiter
Authors: Fludra Andrzej ,   SPICE Team
Published: March 2021

SPICE (Spectral Imaging of Coronal Environment) is an EUV imaging spectrometer onboard Solar Orbiter. SPICE observes the Sun in two wavelength bands: 69.6-79.4 nm and 96.6-105.1 nm and is capable of recording full spectra in these bands with exposures as short as 1s. SPICE can measure spectra from the disk and low corona, and records all spectral lines simultaneously, using one of three narrow slits: 2”x11’, 4’’x11’, 6’’x11’, or a wide slit 30’’x14’. The primary mirror can be scanned in a direction perpendicular to the slit, allowing raster images of up to 16’ in size.

The first SPICE data were taken during the instrument commissioning carried out by the RAL Space team between 2020 April 21 and 2020 June 14, and at the first Solar Orbiter perihelion at 0.52AU between June 16-21.  We give examples of full spectra from the quiet Sun near disk centre and provide a list of key spectral lines from neutral hydrogen and ions of carbon, oxygen, nitrogen, neon, sulphur and magnesium. These lines cover the temperature range between 10,000 K and 1 million K (10MK in flares), providing slices of the Sun’s atmosphere in narrow temperature intervals. We show examples of raster images in several strong lines, obtained with different slits and a range of exposure times between 5s and 180s.

We have found several unusually bright, compact structures (named “beacons”) in the quiet Sun network, with extreme intensities up to 22 times greater than the average intensity across the image. The lifetimes of these sources are longer than 1 hour. We will derive plasma velocities in the beacon area, and co-align the SPICE rasters with the SDO/AIA 304 and 171 images and the HMI magnetic field to better understand the origin and properties of beacons.

We also show the first above-limb measurements with SPICE in Mg IX, Ne VIII and O VI lines, as obtained when the spacecraft pointed at the limb. Maps of Mg/Ne abundance ratios on disk can be derived and compared with in situ measurements to help confirm the magnetic connection between the spacecraft location and the Sun’s surface, and locate the sources of the solar wind.
Overview of interplanetary coronal mass ejections observed by Solar Orbiter, Parker Solar Probe, Bepi Colombo, Wind and STEREO-A
Authors: Möstl Christian , Weiss Andreas J. , Bailey Rachel L. , Reiss Martin A. , Amerstorfer Tanja , Hinterreiter Jürgen , Bauer Maike , Amerstorfer Ute V. , Davies Emma E. , Horbury Tim , Barnes David , Davies Jackie A. , Harrison Richard A. , Heyner Daniel , Richter Ingo , Auster Hans-Ulrich , Magnes Werner , Baumjohann Wolfgang
Published: March 2021

We show in situ observations of ICMEs during the first year of Solar Orbiter observations based on magnetic field data from the MAG instrument in conjunction with in situ and imaging observations from the Heliospheric System Observatory. The in situ magnetic field data from four other currently active spacecraft - Parker Solar Probe, BepiColombo, STEREO-Ahead and Wind -  are also searched for ICME signatures, and all clear ICME events that could be identified by classic signatures such as elevated and rotating magnetic fields of sufficiently long durations are included in a living online catalog. Furthermore, we provide a visualization of the in situ magnetic field data alongside spacecraft positions and propagating CME fronts, which are based on modeling of STEREO-A heliospheric imager data. This allows us to identify ICME events that could be unambiguously followed from their inception on the Sun to their impact at the aforementioned spacecraft, and highlights sought-after lineup events, in which the same ICME is observed at multiple points in space, such as the well-studied 2020 April 15-20 ICME. We discuss the ICME rate observed so far, and provide an outlook on the expected ICME rate in solar cycle 25 based on different forecasts for the cycle amplitude (see Möstl et al. 2020, https://doi.org/10.3847/1538-4357/abb9a1).
A toy model to investigate stability of AI-based dynamical systems
Authors: Balogh Blanka , Saint-Martin David , Ribes Aurélien
Published: March 2021

The development of atmospheric parameterizations based on neural networks is often hampered by numerical instability issues. Previous attempts to replicate these issues in a toy model have proven ineffective. We introduce a new toy model for atmospheric dynamics, which consists in an extension of the Lorenz'63 model to a higher dimension. While neural networks trained on a single orbit can easily reproduce the dynamics of the Lorenz'63 model, they fail to reproduce the dynamics of the new toy model, leading to unstable trajectories. Instabilities become more frequent as the dimension of the new model increases, but are found to occur even in very low dimension. Training the neural network on a different learning sample, based on Latin Hypercube Sampling, solves the instability issue. Our results suggest that the design of the learning sample can significantly influence the stability of dynamical systems driven by neural networks.
Polar Stratospheric Clouds: Satellite Observations, Processes, and Role in Ozone Depletion
Authors: Tritscher Ines , Pitts Michael C. , Poole Lamont R. , Peter Thomas ,   SPARC PSCi team
Published: March 2021

The important role of polar stratospheric clouds (PSCs) in stratospheric ozone depletion during winter and spring at high latitudes has been known since the 1980s. However, contemporary observations by the spaceborne instruments MIPAS (Michelson Interferometer for Passive Atmospheric Sounding), MLS (Microwave Limb Sounder), and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) have brought about a comprehensive and clearer understanding of PSC spatial and temporal distributions, their conditions of existence, and the processes through which they impact polar ozone. Within the SPARC (Stratosphere-troposphere Processes And their Role in Climate) PSC initiative (PSCi), those datasets have been synthesized and discussed in depth with the result of a new vortex-wide climatology of PSC occurrence and composition. We will present our results within this vPICO together with a review of the significant progress that has been made in our understanding of PSC nucleation, related dynamical processes, and heterogeneous chlorine activation. Moreover, we have compiled different techniques for parameterizing PSCs and we will show their effects in global models.
A psychological tool for helping the public feel invested in climate change.
Authors: Mort Haydon
Published: March 2021

A psychological tool for helping the public feel invested in climate change.

Talking to audiences about climate change in a way that helps them feel empowered is a challenge that many geoscientists feel ill-equipped to tackle. In this presentation, I demonstrate how using a blend of reverse psychology and cognitive dissonance can lead to an audience feeling highly activated and motivated. 

I used data and presentation techniques to trick an audience into firmly believing that climate change is a hoax - and then revealed the hoax. I was able to use the initial anger and frustration to elicit highly positive states of mind and feelings of personal empowerment. Audiences report a  much higher degree of climate literacy and a greater sense of awareness of their role in the fight again climate change. This strategy also appears to effective in convincing 'climate sceptics' that they are mistaken.

Questionnaires collected after 24 of these presentations reveal 100% of participants left feeling 'invested' in climate change. 95% additionally felt 'motivated to learn more and take action'. When asking sceptical audiences, 85% said that the presentation had forced them to re-evaluate their pre-existing beliefs. 60% said they now felt anthropogenically driven climate change was likely a reality. 100% of sceptics wanted to learn more.

The neurophysiology of our brains explains this data. When paired with strong emotions - positive or negative - information is more likely stored in memory centres. Audiences that already understood climate change to be a threat switch from anxiety/anger /confusion to relief/happiness/wonder. Such a large jump in emotional state triggers a strong dopaminergic system response. By forcing the audience to consider why they were susceptible to the hoax in the first place, the positive mindset makes them feel empowered and eager to learn more.

In the case of climate sceptics; by mirroring their own arguments, I demonstrate empathy by appreciating their perspectives. Whilst the resulting cognitive dissonance of having the hoax 'unmasked' is deeply uncomfortable, I able to convert this strong negative emotion into a positive one. I do this by a) empathising with the discomfort b) showing solidarity with them c) being open about why I used the strategy I did.

In summary, by marrying geocommunication with brain science, we can look forward to exploring more innovative strategies that make members of the public feel more invested and activated.
3D Predictive HM-modeling in the heterogeneous Opalinus Clay of the Mont Terri rock laboratory and validation with monitoring data from a mine-by test
Authors: Li Chao , Jaeggi David , Nussbaum Christophe , Bossart Paul
Published: March 2021

The Mont Terri rock laboratory began in 1996 with 8 niches, followed by a research tunnel in 1998. Since then the laboratory has been expanded every 10 years, mainly in the shaly facies of the Opalinus Clay. In March 2018, south of the existing laboratory, the Mont Terri Project Partners initiated another extension «Gallery 18» of the Mont Terri rock laboratory mainly located in sandy facies of the Opalinus Clay. In October 2019 the extension was finished, resulting in more than 500 m of additional galleries and niches for new experiments. In the frame of this extension, for the first time a heterogeneous mine-by test, comprising a sheet of sandy facies and carbonate-rich sandy facies sandwiched between shaly facies was conducted in the rock laboratory. This so-called MB-A experiment (hydro-mechanical characterization of the sandy facies before and during excavation) consists of two lateral niches for instrumentation and monitoring and a test gallery of 30 m length oriented perpendicular to the latter. The instrumentation based on 26 boreholes with lengths up to 40 m consists of pore pressure transducers, extensometers, inclinometers and stress monitoring stations. It was finished several months before excavation of the test section was started in order to assure equilibration close to the initial conditions. Excavation of the test gallery running parallel to bedding strike was carried out in May 2019 in 20 days.

Elastic predictive modeling is performed in 3D to estimate the hydro-mechanical behavior of the rock mass during a sequential excavation according to effective daily advances and as-is sensor locations. The modeling results are compared with monitoring data. The calculation predicts a rotation of the early time near-field pore pressure reduction from perpendicular to parallel to bedding for late times. In general, monitored peak pore water pressures were higher than predicted, with a remarkable phase shift depending on distance and spatial position with respect to the drift. Monitored deformations were clearly underestimated with the elastic calculation. The overall behavior of the excavation in the sandy facies was unexpectedly not so different from former excavations in shaly facies.

A parametric study was performed to assess key parameters of potential effects of excavation on the hydromechanical responses of the excavation. It is concluded that adapted constitutive laws are needed in order to properly predict the hydromechanical response in stiffer claystone, such as for instance the sandy and carbonate-rich sandy facies of the Opalinus Clay.
Effects of a Forested State Park on Suspended Solid and Dissolved Organic Carbon Concentrations in an Agriculturally Impacted Watershed
Authors: Rintsch Eileen , Farthing Tessa , Grudzinski Bartosz
Published: March 2021

Previous research has indicated that agricultural land use can reduce water quality in streams. This includes: 1) an increase in suspended solids (SS) due to elevated erosion and 2) shifts in dissolved organic carbon (DOC) particularly due to different C:N between agricultural crops and natural vegetation. We examine spatial and temporal dynamics of SS and DOC in four rivers, located in an agriculturally impacted watershed in SW Ohio, as they flow from agricultural land cover through a naturally forested State Park. Nineteen surface water sites were sampled bimonthly from December 2019 to December 2020. Results will be presented to determine if a forested state park improved the water quality in SW Ohio. We will further discuss how the work done in SW Ohio could be replicated in other intensive agricultural areas of Europe with similar climate patterns.
Effects of soil and vegetation development on surface and subsurface hydrological properties and processes on moraines in the Swiss Alps
Authors: Maier Fabian , van Meerveld Ilja
Published: March 2021

Overland flow (OF) and subsurface flow (SSF) are key processes that determine the streamflow response to precipitation, as well as water quality, but are affected by the land surface and soil characteristics. They can also modify the shape of our landscape. However, our understanding of the evolution of OF and SSF characteristics and the feedback mechanisms between hydrological, pedological, biological and geormorphological processes that affect OF and SSF during landscape evolution is still limited.

We used a space-for-time approach and studied 3 plots (4m x 6m each) on four different aged moraines (several decades to ~13.500 years) on the Sustenpass near the Steinglacier and in the karstic glacier foreland of the Griessfirn near Klausenpass (total of 24 plots) to determine how OF & SSF change during landscape evolution. We used artificial rainfall experiments with high rainfall intensities to determine runoff ratios, peak flow rates, timing and duration of OF & SSF. The addition of tracers (2H and NaCl) to the sprinkling water and sampling of soil water allowed us to determine the degree of mixing of the applied rainfall with water in the soil. Measurements during natural rainfall events helped to determine the impact of the rainfall volume and intensity on the runoff generation. In addition, the runoff samples and sensor-based turbidity measurements of OF provide an estimate of the erosion rates during extreme events. In order to link the differences in runoff generation with the pedological and biological characteristics of the slopes, vegetation cover, root density, soil texture, soil aggregate stability, and the saturated hydraulic conductivity (Ksat) were measured as well.

The results show that Ksat at both study areas decreases with moraine age and soil depth and is mainly driven by the increase in silt and clay content. Despite the high Ksat values, local OF occurs frequently on the youngest moraines due to the large rock and stone cover. Sediment flux and the related erosion rates are largest for the young moraines, since vegetation cover and soil aggregate stability are small. Soil and vegetation development change major OF and SSF characteristics during landscape development, such as the mixing processes and the pre-event water fraction in OF & SSF, which both increase for the older moraines. However, the rate of these changes during landscape evolution is controlled by the parent material. These results can be used to inform landscape evolution models and help us to understand processes within the critical zone during the first millennia of soil development.
Design of a 3D/4D hydrogeologic geo-database: an application in the so-called “Terra dei Fuochi” area (Campania, Italy)
Authors: Ducci Daniela , Del Gaudio Elena
Published: March 2021

The monitoring data of spatial-temporal variation of groundwater properties (groundwater levels, hydrodynamic properties, chemical and isotopic characteristics, etc.), collected in different times and with different aims, are often scattered or missing. Moreover, a messy database generates huge amounts of data. Especially the handling of time as a fourth dimension usually requires terabytes of storage space. Therefore, an appropriate data collection, storage and management is required, that is a key concept for the 3D/4D GIS. The objective of this study is to produce a comprehensive data management model that optimizes the handling and storage of spatial-temporal data. The 3D / 4D hydrogeological geo-database with WebGIS implementation for the “Terra dei Fuochi” Campania (Italy), is capable of storing information relating to different parameters (groundwater levels, physical-chemical, isotopic characteristics, etc.) in the space and their variation over time.

Moreover, the model will be capable of handling various kinds of spatial-temporal applications. These include the proper handling of temporal variations (e.g. trends in nitrate pollution, decrease of groundwater levels, climate change effects, etc.) and spatial variation (delimitation of contaminated areas, areas with natural high levels of geogenic compounds, etc.) within a 4D model. The storage requirements will be reduced and spatial as well as spatial-temporal operations are accelerated significantly.

This model could also be used by land managers and restoration practitioners with little knowledge of groundwater, but still have an interest in the critical issues of groundwater, assisting the environmental managers in making decisions in environmental recovery projects.

A further development could be a mobile application providing the same results, enabling real time data in the field to be used in decision-making. That will provide a great opportunity for the knowledge advancement of the field of groundwater.
Coherent finescale temperature structures characterised at high resolution by a fast thermistor on an ocean glider
Authors: Rollo Callum , Heywood Karen J. , Hall Rob A.
Published: March 2021

During the EUREC4A field campaign in 2020, three ocean gliders were deployed to the tropical North Atlantic, upwind of Barbados. We present preliminary results from this three week deployment, focusing on the finescale temperature and salinity variability below the pycnocline.

The three gliders completed a total of 580 dive cycles to 750 m in virtual mooring and bowtie patterns around a 10 km square. A research vessel occupied a 250 km meridional transect 2 km east of the glider square. The gliders and research vessel observed staircases in temperature and salinity from 300 m to 500 m depth, with a typical vertical scale of 50 m and temperature steps of 0.5 to 1.0 C. The staircase structure was observed by all three gliders’ temperature/salinity sensors and the research vessel's main CTD. The finescale (O 10 cm) vertical structure of the steps, was clearly resolved by a FP07 fast thermistor mounted on one of the gliders. The finescale layers of uniform temperature appear also to be uniform in salinity. These large stairsteps persisted for an average of two days before eroding, and were observed to be spatially coherent over at least 10 km. Smaller stairstep structures at the base of the pycnocline (O 10 m, 0.2 C) persisted throughout the observational period.

Halfway through the deployment, a density-compensated front moving through the region increased temperature at 400 m by 2 C. Simultaneous observations from the three gliders and research vessel enabled analysis of the evolution of this structure. The temperature change was greatest at 400 m, tapering to the limit of detectability at 200 m and 600 m. Along the edge of the front on the warm side, staircase structures were observed. These structures persisted for over a week before eroding.
Rigorous propagation of Galileo-based terrestrial scale
Authors: Glaser Susanne , Rebischung Paul , Altamimi Zuheir , Schuh Harald
Published: March 2021

Until now, the GPS and GLONASS satellite antenna phase center offsets (PCOs) used within the International GNSS Service (IGS) have been estimated based on the International Terrestrial Reference Frame (ITRF) scale provided by Satellite Laser Ranging (SLR) and Very Long Baseline Interferometry (VLBI). Therefore, the IGS products have themselves been conventionally aligned to the ITRF scale, hence could not contribute to its realization. However, the disclosure of metadata, including PCOs, for the Galileo satellites by the European GNSS Agency recently opened a unique opportunity to realize an independent GNSS-based terrestrial scale.

Before its ongoing third reprocessing campaign (repro3), the IGS thus re-evaluated the PCOs of the GPS and GLONASS satellites by fixing the PCOs of the Galileo satellites in multi-GNSS solutions. The repro3 products, based on these re-evaluated PCOs, can provide an independent Galileo-based scale, which could potentially contribute to the scale of the next ITRF2020. However, the re-evaluated GPS and GLONASS PCOs are introduced as known constant values in repro3 without realistic uncertainties. Therefore, finally no realistic uncertainty will be available for the realized terrestrial scale.

In this study, another re-evaluation of the GPS and GLONASS PCOs based on the Galileo PCOs is carried out, accounting this time for their variability and estimation errors, with the goal to obtain a more rigorous Galileo-based scale with realistic uncertainty, in particular during the pre-Galileo era. For that purpose, daily time series of GPS and GLONASS PCO estimates derived from the repro3 solutions of different IGS Analysis Centers (ACs) are first analyzed. Deterministic and stochastic models of the time series are then introduced in a global adjustment of all GPS and GLONASS PCOs based on the Galileo PCOs. The re-evaluated PCOs – together with their uncertainties – are finally re-injected into the AC terrestrial frame solutions. The analysis of the latter allows a more rigorous evaluation of the Galileo-based scale and its uncertainty and a more sound comparison to the ones realized by SLR and VLBI. The outcome of this study will provide valuable information for the final selection and realization of the ITRF2020 scale.
Fluid inclusion hardening: Nanoscale evidence from naturally deformed pyrite
Authors: Rogowitz Anna , Dubosq Renelle , Schneider David , Schweinar Kevin , Gault Baptiste
Published: March 2021

The interaction of trace elements, fluids and crystal defects plays a vital role in a crystalline material’s response to an applied stress. For example, dislocations can be arrested by the strain field of immobile defects (i.e., particles or precipitates) or by the accumulation of mobile solutes in their cores, which can lead to strain hardening. The rheology of minerals is also strongly influenced by interactions with fluids, which are typically known to facilitate ductile deformation in geomaterials (i.e., hydrolytic weakening, dissolution creep). Investigation of these nanometer scale processes however, requires a correlative approach combining high-spatial resolution analytical techniques. In recent years, increasing developments in microscopy and microanalysis have allowed for the compositional measurements and spatial imaging of materials at the near-atomic scale. Herein, we have combined electron backscatter diffraction (EBSD) mapping, electron channeling contrast imaging (ECCI), scanning transmission electron microscopy (STEM) and atom probe tomography (APT) on a naturally deformed polycrystalline pyrite aggregate from the Abitibi Subprovince in Canada to investigate the role of fluid inclusions on mineral rheology. The combined EBSD and ECCI data reveal minor crystal misorientation and low-angle grain boundary development in the vicinity and at the tip of microfractures indicating a dominantly brittle regime with minor strain accommodation via crystal-plasticity where dislocations are mostly emitted by the propagating fracture. These interpretations are consistent with the peak temperature conditions of the sample estimated at 302 ± 27°C, which falls within the lower range of the brittle to crystal-plastic behaviour of pyrite (260–450°C). Nanoscale structural and chemical data reveal nanoscale fluid inclusions enriched in As, O, Na and K that are linked by As-enriched dislocations. Based on these results, we propose a model of fluid hardening whereby dislocations get pinned at fluid inclusions during crystal-plastic deformation, initiating pipe diffusion of trace elements from the fluid inclusions into dislocations that leads to their stabilization and local hardening. Although additional experiments are required on other mineral phases, our initial efforts advance the understanding of the interplay between nanostructures and impurities and its impact on the rheology of geomaterials during relatively low temperature deformation.

 
Are the socioeconomic impacts associated with tropical cyclones in Mexico exacerbated by local vulnerability and ENSO conditions?
Authors: Jaramillo Alejandro , Dominguez Christian
Published: March 2021

Tropical Cyclones (TCs) are among the most dangerous natural hazards because they can cause severe economic losses and high mortality. Climate risk is defined as a metric that depends on social vulnerability and the occurrence of natural hazards. A social vulnerability index was constructed for this study using two metrics: the degree of local marginalization and the local social gap. The accumulated rainfall and duration of extreme precipitation associated with TC passages are examined as a natural hazard during the period 1981–2017. TC days are depicted as days when TC‐related rainfall exceeded the 95th percentile of daily precipitation from May to November, defined as summer precipitation. In this way, changes in climate risk under El Niño‐Southern Oscillation (ENSO) conditions are explored to determine regions where both social vulnerability and TC days are high. These changes are useful to find out when disasters have more chances to occur. In the present study, climate risk was found to increase more than 80% from average in southwestern Mexico during strong El Niño years. Under neutral conditions, climate risk values rise to more than 40% than average over northwestern Mexico. Under strong La Niña conditions, climate risk increases by more than 80% from average over the eastern coast of Mexico. Our approach is validated through a comparison between anomalies in climate risk and disaster costs (socioeconomic impacts). Both local vulnerability and ENSO conditions exacerbate socioeconomic impacts associated with TCs, and an analysis of linear trends in TC rainfall and TC days reveals that most of the coastal regions in Mexico have a significant rising trend in both variables. Thus, Mexico should be prepared to face more TC extreme rainfall events. Suggestions for how Mexico can meet the objectives of international risk agendas are discussed.
Nine years of SMOS sea surface salinity global maps at the Barcelona Expert Center
Authors: Olmedo Estrella , González-Haro Cristina , Hoareau Nina , Umbert Marta , González-Gambau Verónica , Martínez Justino , Gabarró Carolina , Turiel Antonio
Published: March 2021

Abstract. After more than 10 years in orbit, the Soil Moisture and Ocean Salinity (SMOS) European mission is still a unique, high-quality instrument for providing soil moisture over land and sea surface salinity (SSS) over the oceans. At the Barcelona Expert Center (BEC), a new reprocessing of 9 years (2011–2019) of global SMOS SSS maps has been generated. This work presents the algorithms used in the generation of BEC global SMOS SSS product v2.0, as well as an extensive quality assessment. Three SMOS SSS fields are distributed: a high-resolution level-3 product (with DOI https://doi.org/10.20350/digitalCSIC/12601, Olmedo et al., 2020a) consisting of binned SSS in 9 d maps at 0.25∘×0.25∘; low-resolution level-3 SSS computed from the binned salinity by applying a smoothing spatial window of 50 km radius; and level-4 SSS (with DOI https://doi.org/10.20350/digitalCSIC/12600, Olmedo et al., 2020b) consisting of daily 0.05∘×0.05∘ maps that are computed by multifractal fusion with sea surface temperature maps. For the validation of BEC SSS products, we have applied a battery of tests aimed at the assessment of quality of the products both in value and in structure. First, we have compared BEC SSS products with near-to-surface salinity measurements provided by Argo floats. Secondly, we have assessed the geophysical consistency of the products characterized by singularity analysis, and the effective spatial resolutions are also estimated by means of power density spectra and singularity density spectra. Finally, we have calculated full maps of SSS errors by using correlated triple collocation. We have compared the performance of the BEC SMOS product with other satellite SSS and reanalysis products. The main outcomes of this quality assessment are as follows. (i) The bias between BEC SMOS and Argo salinity is lower than 0.02 psu at a global scale, while the standard deviation of their difference is lower than 0.34 and 0.27 psu for the high- and low-resolution level-3 fields (respectively) and 0.24 psu for the level-4 salinity. (ii) The effective spatial resolution is around 40 km for all SSS products and regions. (iii) The results from triple collocation show the BEC SMOS level-4 product as the product with the lowest estimated salinity error in most of the global ocean and the BEC SMOS high-resolution level-3 as the one with the lowest estimated salinity error in regions strongly affected by rainfall and continental freshwater discharge.
How do modeling choices and erosion zone locations impact the representation of connectivity and the dynamics of suspended sediments in a multi-source soil erosion model?
Authors: Uber Magdalena , Nord Guillaume , Legout Cédric , Cea Luis
Published: March 2021

Abstract. Soil erosion and suspended sediment transport understanding is an important issue in terms of soil and water resources management in the critical zone. In mesoscale watersheds (>10 km2) the spatial distribution of potential sediment sources within the catchment associated with rainfall dynamics is considered to be the main factor in the observed suspended sediment flux variability within and between runoff events. Given the high spatial heterogeneity that can exist for such scales of interest, distributed physically based models of soil erosion and sediment transport are powerful tools to distinguish the specific effect of structural and functional connectivity on suspended sediment flux dynamics. As the spatial discretization of a model and its parameterization can crucially influence how the structural connectivity of the catchment is represented in the model, this study analyzed the impact of modeling choices in terms of the contributing drainage area (CDA) threshold to define the river network and of Manning's roughness parameter (n) on the sediment flux variability at the outlet of two geomorphologically distinct watersheds. While the modeled liquid and solid discharges were found to be sensitive to these choices, the patterns of the modeled source contributions remained relatively similar when the CDA threshold was restricted to the range of 15 to 50 ha, with n restricted to the range 0.4–0.8 on the hillslopes and to 0.025–0.075 in the river. The comparison of the two catchments showed that the actual location of sediment sources was more important than the choices made during discretization and parameterization of the model. Among the various structural connectivity indicators used to describe the geological sources, the mean distance to the stream was the most relevant proxy for the temporal characteristics of the modeled sedigraphs.
Identifying Sensitivities in Flood Frequency Analyses using a
Stochastic Hydrologic Modeling System
Authors: Newman Andrew J. , Stone Amanda G. , Saharia Manabendra , Holman Kathleen D. , Addor Nans , Clark Martyn P.
Published: March 2021

Abstract. This study assesses sources of variance in stochastic hydrologic modelling to support flood frequency analyses. The major components of the modelling chain, including model structure, model parameter estimation, initial conditions, and precipitation inputs were examined across return periods from 2 to 100,000 years at two watersheds representing different hydro-climates across the western United States. Ten hydrologic model structures were configured, calibrated and run within the Framework for Understanding Structural Errors (FUSE) modular modelling framework for each of the two watersheds. Model parameters and initial conditions were derived from long-term calibrated simulations using a 100-member historical meteorology ensemble. A stochastic event-based hydrologic modelling workflow was developed using the calibrated models; millions of flood event simulations were performed at each basin. The analysis of variance method was then used to quantify the relative contributions of model structure, model parameters, initial conditions, and precipitation inputs to flood magnitudes for different return periods. The attribution of the variance of flood frequencies to each component of a stochastic hydrological modelling framework, including several hydrological model structures, is a novel contribution to the flood modelling literature. Results demonstrate that different components of the modelling chain have different sensitivities for different return periods. Precipitation inputs contribute most to the variance of rare events, while initial conditions are most influential for the more frequent events. However, the hydrological model structure and structure-parameter interactions together play an equally important role in specific cases, depending on the basin characteristics and type of flood metric of interest. This study highlights the importance of critically assessing model underpinnings, understanding flood generation processes, and selecting appropriate hydrological models that are consistent with our understanding of flood generation processes.