bluuebunny/crossref_metadata_2025 huggingface dataset:
Properties of the lightning flashes in North-western Mediterranean Sea as documented during the EXAEDRE project
Authors: Defer Eric , Prieur Serge , Pedeboy Stephane
Published: March 2021

The EXAEDRE (EXploiting new Atmospheric Electricity Data for Research and the Environment) project aims at better understanding North-western Mediterranean Sea thunderstorms through coupled observational- and modelling-based studies with a dedicated focus on the lightning activity and its properties at flash, storm and regional scale.

In this work, the lightning activity is measured by the VHF Lightning Mapping Array (LMA) network SAETTA and the operational French lightning detection network Meteorage. SAETTA VHF sources are merged in flashes based on a DBSCAN algorithm (L2 SAETTA dataset). Meteorage strokes and pulses are then combined to SAETTA flashes based on temporal and pulse/stroke-dependent spatial criteria (L2b SAETTA-Meteorage dataset). Four categories of flashes can then be investigated: 1) CG L2b flashes with at least one CG stroke, 2) pure IC L2b flashes as detected by Meteorage with only IC pulses, 3) No-MTRG flashes which are only detected by SAETTA flashes with no concurrent Meteorage records, and 4) No-SAETTA flashes which were only reported by Meteorage with no concurrent SAETTA records.

Several lightning parameters have been investigated for the first three L2b flash categories listed above. It includes among others the flash duration, the vertical flash extension, the 2D horizontal flash extension, the 10/50/90 percent quantile of flash altitude, the flash trigger altitude, the stroke/pulse number per flash, and the flash vertical extension. Based on the L2b database built from the SAETTA and Meteorage records of the entire year 2018, No-MTRG flashes have tendency to be rather small in terms of 2D flash extension or short in duration. They also statically exhibit a similar distribution of their 10/50/90 percent quantile of flash altitude. CG L2b flashes exhibit mainly altitudes below 8 km while the majority of pure IC flashes show distinct distribution of 10/50/90 percent quantile flash altitude. Three trigger altitude ranges, i.e. 4-5 km, 7-9 km, 11-12 km are found in the three studied categories. Finally, for the studied year, less +CG flashes occurred compared to the -CG flashes while CG flashes with more ground connections have the tendency to last longer and to be larger.

First we will introduce the instruments and the data. We will then present the different methodologies applied here to generate the L2b dataset with some typical lightning observations. We will then discuss on the characteristics of the different parameters listed above.
Improved estimation of volcanic SO2 emissions from satellite observations and Lagrangian transport simulations: The 2019 Raikoke eruption case study
Authors: Cai Zhongyin , Grießbach Sabine , Hoffmann Lars
Published: March 2021

Monitoring and modeling of volcanic aerosols is important for understanding the influence of volcanic activity on climate. Here, we applied the Lagrangian transport model Massive-Parallel Trajectory Calculations (MPTRAC) to estimate the total injected SO2 by the stratosphere reaching eruption of the Raikoke volcano (48N, 153E) in June 2019 and its subsequent transport. We used SO2 observations from the AIRS and TROPOMI satellite instruments together with a backward trajectory approach to estimate the altitude-resolved SO2 emission timeseries. Then we applied a scaling factor to the initial estimate of the SO2 mass and added an exponential decay to simulate the time evolution of the total SO2 mass. By comparing the estimated SO2 mass and the observed mass from TROPOMI, we show that the volcano injected 2.1±0.2 Tg SO2 and the e-folding lifetime of the SO2 was about 13~17 days. Further, we compared simulations that were initialized by AIRS and TROPOMI satellite observations with a constant SO2 emission rate. The results show that the model captures the SO2 distributions in the first ~10 days after the eruption. The simulations using AIRS nighttime and TROPOMI measurements show comparable results and model skills which outperform the simulation using a constant emission rate. Our study demonstrates the potential of using combined satellite observations and transport simulations to further improve SO2 time- and height-resolved emission estimates of volcanic eruptions.
Design of offline reservoirs for flood mitigation by using a structure-based risk framework
Authors: Cipollini Stefano , Fiori Aldo , Volpi Elena
Published: March 2021

In this work, we present a general framework for design and risk assessment of hydraulic structures for water control. The framework relies on a “structure-based approach”, accounting for both the statistical behavior of the hydrological load acting on the river system and the hydraulic response of the structure to the environmental load. This approach allows for the reduction of a multivariate and complex statistical problem to a univariate one, focusing on the damage. The framework is applied to an offline detention basin for flood mitigation based on a general, yet simplified routing model. Furthermore, a real-world case study application is presented, with the specific aim of discussing the role of the design parameters and their effect on the probability distribution of damage. Results show the robustness and the effectiveness of the approach for applications to real cases and provide design guidance for practitioners.
Sediment-trapping eﬀectiveness of check dams with multiple debris-flow surges: Experimental study
Authors: Chen Jiangang , Wang Xi'an , Chen Huayong
Published: March 2021

A series of check dams were constructed for debris-flow hazard mitigation in China. Based on the results of field investigation, check dam has a significant impact on the geomorphology of debris flow gully, especially the upstream and downstream of a check dam. According to the relationship between the sediment deposition thickness and the check dam height, the running status of a check dam can be divided into three states: without sediment deposition, half of the storage capacity with sediment deposition, and full of sediment deposition. With the accumulation of sediment transport, the running state of a check dam gradually changed and the sediment-trapping effect of check dams has gradually weakened, leading to the loss of part of the disaster mitigation effect, increasing the risk of downstream infrastructure and human security. Therefore, experiments with multi-surges of debris flows were carried out to study the geomorphic and sediment-trapping eﬀectiveness of check dams. The results showed that with the increase of the sediment amount with multi-surges, the deposition slope in the downstream dam approached or even exceeded that of upstream dam. For one surge, deposition morphology has slightly difference in the cascade dams. At last, a method for calculating the reduction coefficient of deposition slope considering the check dam height and sediment amount with multi-surges is proposed.
Retrieving reflection arrivals from passive seismic data using Radon correlation 
Authors: Hariri Naghadeh Diako , J Bean Christopher , Smith Patrick , Lebedev Sergei , Mohamed Huda
Published: March 2021

Since explosive and impulsive seismic sources such as dynamite, air guns, gas guns, or even vibroseis can have a big impact on the environment, some companies have decided to record ambient seismic noise and use it to estimate the physical properties of the subsurface. Big challenges arise when the aim is extracting body-waves from recorded passive signals, especially in the presence of strong surface waves. In passive seismic signals, such body-waves are usually weak in comparison to surface waves which are much more prominent. To understand the characteristics of passive signals and the effect of natural source locations, three simple synthetic models were created. To extract body-waves from simulated passive signals we propose and test a Radon-correlation method. This is a time-spatial correlation of amplitudes with a train of time-shifted Dirac delta functions through different hyperbolic paths. It is tested on a two-layer horizontal model, three-layer model which includes a dipping layer (with and without lateral heterogeneity) and also on synthetic Marmousi model data sets. Synthetic tests show that the introduced method is able to reconstruct reflection events at the correct time-offset positions which are hidden in results obtained by the general cross-correlation method. Also, a depth migrated section shows a good match between imaged-horizons and the true model. It is possible to generate off-end virtual gathers by applying the method to a linear array of receivers and to construct a velocity model by semblance velocity analysis of individually extracted gathers.
​Near-Surface High Resolution Characterization of the Seismogenic Alhama de Murcia Strike-slip Fault 
Authors: Handoyo Handoyo , Palomeras Imma , Alcalde Juan , de Felipe Irene , Martí David , García-Mayordomo Julian , Martínez-Díaz Jose Jesus , Teixidor Teresa , Insúa-Arevalo Juan Miguel , Carbonell Ramon
Published: March 2021

In Spring 2011 (11th of May), the vicinity of Lorca city (Murcia, SE Iberian Peninsula) was hit by two main seismic shocks that reach a maximum magnitude of 5.2 Mw. The earthquake caused serious widespread damage in the city and its surroundings. Similar events have affected the area regularly in the past (for example: on May 6,1977, 4.2 mg). These events are distributed along a relatively broad band (roughly NE-SW oriented) parallel to the coast, associated to the activation of the Alhama de Murcia Fault (AMF), an oblique-slip (reverse-strike-slip) fault system located in the Eastern Betics Shear Zone. The current study aims to characterize the shallow subsurface across some of the surface outcrop of a few of the main faults that lie within this seismogenic strike-slip fault system. Six normal-incidence seismic reflection profiles were acquired in the area crossing the AMF and the Carrascoy fault, among others). This study focuses on the determination of the shear-wave velocity depth model by applying Multichannel Analysis of Surface Waves (MASW), using the shot records of the seismic reflection profiles. The 1D velocity-depth functions acquired were pasted together to obtain the final 2D velocity models. The hand-picked dispersion curves were inverted using two different approaches to address the consistency of the inversion schemes. The final models reveal relevant differences across the different fault zones, reflecting the heterogeneity and lateral variability that characterizes a complex seismogenic zone, a most probably, diffuse plate boundary.

This research is supported by: Generalitat de Catalunya (AGAUR) grant 2017SGR1022 (GREG); EU (H2020) 871121 (EPOS-SP); EIT-RawMaterials 17024 (SIT4ME), CGL2013-47412-C2-1-P.
Generative Adversarial Networks for automatic detection of mounds in Digital Terrain Models (Mars Arabia Terra)
Authors: Julka Sahib , Granitzer Michael , De Toffoli Barbara , Penasa Luca , Pozzobon Riccardo , Amerstorfer Ute
Published: March 2021

Mounds are positive relief features that can be ascribed to a variety of phenomena; they can be related to monogenic edifices due to spring or mud volcanism, rootless cones on top of lava flows, pingos and so on. In the case of sedimentary or spring case of mud extrusion, these mounds can be widespread regionally and/or contained in large complex craters, often in populations of several hundreds or thousands . Previous work on detection of such mounds in the Mars Arabia Terra involved exploiting morphometric parameters and mapping them onto Digital Terrain Models . In this work, we take a step further and develop more general methods to automatically detect them without explicitly defining the topographical features. We achieve this by using a generative framework trained in an adversarial fashion to produce realistic mappings with only a small number of training samples. Further, we introduce a terrain simulator based on this framework that learns the terrain simulation parameters, and allows us to induce domain specific knowledge automatically into the network.  Our key results indicate that learning latent representations based on simulations can offer improvements in detection accuracy, while making it more robust to changing terrain scenarios.
Improving CME evolution and arrival predictions with AMR and grid stretching in EUHFORIA
Authors: Baratashvili Tinatin , Verbeke Christine , Wijsen Nicolas , Chané Emmanuel , Poedts Stefaan
Published: March 2021

Coronal Mass Ejections (CMEs) are the main drivers of interplanetary shocks and space weather disturbances. Strong CMEs directed towards Earth can cause severe damage to our planet. Predicting the arrival time and impact of such CMEs can enable to mitigate the damage on various technological systems on Earth. 

We model the inner heliospheric solar wind and the CME propagation and evolution within a new heliospheric model based on the MPI-AMRVAC code. It is crucial for such a numerical tool to be highly optimized and efficient, in order to produce timely forecasts. Our model solves the ideal MHD equations to obtain a steady state solar wind configuration in a reference frame corotating with the Sun. In addition, CMEs can be modelled by injecting a cone CME from the inner boundary (0.1 AU).

Advanced techniques, such as grid stretching and Adaptive Mesh Refinement (AMR) are employed in the simulation. Such methods allow for high(er) spatial resolution in the numerical domain, but only where necessary or wanted. As a result, we can obtain a detailed, highly resolved image at the (propagating) shock areas, without refining the whole domain.

These techniques guarantee more efficient simulations, resulting in optimised computer memory usage and a significant speed-up. The obtained speed-up, compared to the original approach with a high-resolution grid everywhere, varies between a factor of 45 - 100 depending on the domain configuration. Such efficiency gain is momentous for the mitigation of the possible damage and allows for multiple simulations with different input parameters configurations to account for the uncertainties in the measurements to determine them. The goal of the project is to reproduce the observed results, therefore, the observable variables, such as speed, density, etc., are compared to the same type of results produced by the existing (non-stretched, single grid) EUropean Heliospheric FORecasting Information Asset (EUHFORIA) model and observational data for a particular event on 12th of July, 2012. The shock features are analyzed and the results produced with the new heliospheric model are in agreement with the existing model and observations, but with a significantly better performance. 

 

This research has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 870405 (EUHFORIA 2.0).
A semi-implicit pseudo-incompressible flow solver for diabatic dynamics: Baroclinic-wave life cycles 
Authors: Schmid Fabienne , Klein Rupert , Gagarina Elena , Achatz Ulrich
Published: March 2021

This study introduces an efficient modeling framework for investigations of diabatic flows in the atmosphere. In particular, the spontaneous emission of inertia-gravity waves is addressed in idealized simulations of baroclinic-wave life cycles. Numerical simulations are perfomed using a finite-volume solver for the pseudo-incompressible equations on the f-plane with newly implemented semi-implicit time stepping scheme, adjusted to the staggered grid, which provides high stability and efficiency for long simulation runs with large domains. Furthermore, we have modified the entropy equation to include a heat source, allowing for a development of the vertically dependent reference atmosphere. Numerical experiments of several benchmarks are compared against an explicit third-order Runge-Kutta scheme as well as numerical models from the literature, verifying the accuracy and efficiency of the scheme. The proposed framework serves as a construction basis for an efficient simulation tool for the development and validation of a parameterization scheme for gravity-waves emitted from jets and fronts.
Moisture and humidity dependence of the above-ground cosmic-ray neutron intensity revised
Authors: Köhli Markus , Weimar Jannis , Fersch Benjamin , Baatz Roland , Schrön Martin , Schmidt Ulrich
Published: March 2021

The novel method of Cosmic-ray neutron sensing (CRNS) allows non-invasive soil moisture measurements at a hectometer scaled footprint. Up to now, the conversion of soil moisture to a detectable neutron count rate relies mainly on the equation presented by Desilets et al. (2010). While in general a hyperbolic expression can be derived from theoretical considerations, their empiric parameterisation needs to be revised for two reasons. Firstly, a rigorous mathematical treatment reveals that the values of the four parameters are ambiguous because their values are not independent. We find a 3-parameter equation with unambiguous values of the parameters which is equivalent in any other respect to the 4-parameter equation. Secondly, high-resolution Monte-Carlo simulations revealed a systematic deviation of the count rate to soil moisture relation especially for extremely dry conditions as well as very humid conditions. That is a hint, that a smaller contribution to the intensity was forgotten or not adequately treated by the conventional approach. Investigating the above-ground neutron flux by a broadly based Monte-Carlo simulation campaign revealed a more detailed understanding of different contributions to this signal, especially targeting air humidity corrections. The packages MCNP and URANOS were used to derive a function able to describe the respective dependencies including the effect of different hydrogen pools and the detector-specific response function. The new relationship has been tested at three exemplary measurement sites and its remarkable performance allows for a promising prospect of more comprehensive data quality in the future.
On GPR signal polarity: a comparison between theoretical findings and real case-studies
Authors: Campo Davide
Published: March 2021

Signal polarity is an attribute that can be used as additional key element to reduce ambiguities and pitfalls in the data interpretation step.

A theoretical analysis of the reflection and transmission phenomena for parallel and perpendicular polarization of the electric field was carried out highlighting that polarity changes (180-degree phase shifts) are caused only by reflection phenomena in specific conditions.

Numerical modelling, through the Finite Difference Time Domain (FDTD) method, helped visualize the theoretical findings and was employed to reproduce the GPR response in two simple contexts (high permittivity layer embedded in a lower permittivity material and vice versa). The findings showed the expected theoretical polarity of multiple reflections providing a tool to effectively recognise them along with travel time information and reflection shapes.

The FDTD technique was also used to analyse the polarity response of regular geometrical shaped air-filled cavities (circle, square and arched roof square), in lossless and lossy conditions. The output was then compared with real radargrams concluding that A-scan assessment should be considered when pronounced scattering and attenuation phenomena are experienced (although polarity analysis may not be possible in very complex environments) and that the shape of the target may affect the resulting signal polarity due to interference with other wave fields.

Polarity analysis should be carried out by comparing the direct wavelet with the signal pattern of interest to assess if a phase shift occurred: attention should be paid to the GPR system used as not all the GPR antennas record the direct wavelet.
Evaluation of a WRF model in forecasting extreme rainfall in the urban data-scarce coastal city of Alexandria, Egypt
Authors: Young Adele , Bhattacharya Biswa , Daniels Emma , Zevenbergen Chris
Published: March 2021

High-resolution precipitation models are essential to forecast urban pluvial floods. Global Numerical Weather Prediction Models (NWPs) are considered too coarse to accurately forecast flooding at the city scale. High-resolution radar nowcasting can be either unavailable or insufficient to forecast at the required lead-times.  Downscaling models are used to increase the resolution and extend forecast by several days when initialised with global NWPs. However, resolving weather processes at smaller spatial scales and sub-daily temporal resolutions has its challenges and does not necessarily result in more accurate forecast but instead only increase the computational requirements. Additionally, in ungauged regions, forecast verification is a challenge as in-situ measurements and radar estimates remain scarce or non-existent. This research evaluates the ability of a dynamically downscaled WRF model to capture the spatial and temporal variability of rainfall suitable for an urban drainage flood forecast model and evaluated against IMERG Global Precipitation Model (GPM) Satellite Precipitation Products (SPPs).
 A WRF model was set-up with one-way nesting, three nested domains at horizontal grid resolutions 10km, 3.33km and 1km, a 1hourly temporal output, a spin-up time of 12 hours and evaluated at different lead times up to 48 hrs. The analysis was performed for three (3)  winter frontal systems during the period 2015-2019 in the highly urbanised coastal Mediterranean city of Alexandria in Egypt which experiences floods from extreme precipitation. The Global Forecast System (GFS), and European Centre for Medium Range (ECMWF) forecast were used as initial and lateral boundary conditions. 
Initial results indicate the WRF models could capture extreme rainfall for all events. There is some agreement with the IMERG data and the model correctly forecasted a decrease in rainfall as the systems transition from coastal to inland areas. In general, GFS and ECMWF initialised WRF models overestimated rainfall estimates compared to IMERG data. Differences in GFS and ECMWF initialised models (multi-model approach) highlight the sensitivity of models to initial and boundary conditions and emphasises the need for post-processing and data assimilation when possible to generate accurate small-scale features. A study such as this provides knowledge for understanding, future applications and limitations of using Quantitative Precipitation Forecasts (QPFs) in urban drainage models. Additionally, the potential use of IMERG GPM to verify spatial and temporal variability of forecast in ungauged and data-scarce regions. Future analysis will evaluate the skill of ensembles precipitation systems in characterising forecast uncertainty in such applications. 
Insights into the poroelastic mechanical behaviour of a crystalline magma reservoir and its influence on modelling volcano surface deformation 
Authors: Alshembari Rami , Hickey James , Williamson Ben , Cashman Katharine
Published: March 2021

Understanding the physical properties of magma reservoirs and their fluid/mechanical behaviour is crucial for improving geophysical models. New evidence suggests that large bodies of magma are difficult to maintain for an extended time period and that melts may instead reside within crystal-mush reservoirs which consist of variably packed frameworks of crystals and interstitial melt. Most existing volcano deformation models assume a pressurized cavity embedded in a homogeneous or heterogenous elastic half-space and therefore ignore the presence of crystals and the possible poroelastic mechanical response to melt intrusion or withdrawal. Here, we consider the magma reservoir to be entirely porous, comprising melt distributed between solid crystals. We investigate the influence of poroelastic mechanical behaviour on reservoir pressure development and resultant spatio-temporal surface deformation. We examine the post-intrusion and post-eruption time-dependent pressure evolution in the magma reservoir due to melt diffusion in the porous domain. Unlike the classic (cavity) models for volcanic surface deformation, an observable post-eruptive or post-intrusion time-dependent inflation can occur without an additional mass change if the reservoir is sufficiently permeable. Post-intrusion and post-eruption timescales vary depending on the porosity of the mush (melt fraction), permeability and magma viscosity. Our study confirms that reservoir inflation and surface deformation can occur without an intrusion or withdrawal of melt but are instead controlled by the mush's poroelastic behaviour. 

 
Tracking the storage and dissipation of atmospheric river storm water in the Russian River watershed using GPS elastic displacements
Authors: Knappe Ellen , Borsa Adrian , Martens Hilary , Argus Donald , Hoylman Zachary , Gardner W. Payton , Wilson Anna , Ralph Marty
Published: March 2021

GPS is emerging as an effective technique to estimate changes in total water storage at Earth's surface.  In California's mountains, GPS indicates that more subsurface storage is lost during drought and gained during years of heavy precipitation than predicted by hydrology models [Argus et al. 2017].  Atmospheric rivers provide a majority of the annual precipitation in coastal environments across North America. The Russian River watershed is often affected by these large storms, which can produce extensive flooding events. In this study, we estimate changes in water storage for the 2017 water year (October 2016 – September 2017), a historically wet year in California, in which more than 20 atmospheric rivers impacted the Russian River watershed. Using GPS displacements, we quantify the water gained during higher intensity atmospheric rivers. We further resolve the time it takes for the storm water to dissipate: that is, we distinguish between water that runs off into rivers and water that is stored in the ground as soil moisture. Finally, we investigate the empirical relationships between GPS displacement and precipitation, evapotranspiration, and soil moisture estimates with the aim of improving constraints to hydrologic models.
Rising smoke-charged vortices in the mid-latitude stratosphere
Authors: Legras Bernard , Lestrelin Hugo , Podglajen Aurélien , Salihoglu Mikail
Published: March 2021

The two most intense wildfires of the last decade that took place in Canada in 2017 and Australia in 2019-2020 were followed by large injections of smoke in the stratosphere due to pyroconvection. It was discovered that, after the Australian event, part of this smoke self-organized as anticyclonic confined vortices that rose against the Brewer-Dobson circulation in the mid-latitude stratosphere up to 35 km (Khaykin et al., 2020, doi: 10.1038/s43247-020-00022-5).  Based on CALIOP lidar observations and the ECMWF ERA5 reanalysis, we analyze the Canadian case and find, similarly, that the large plume which penetrated the stratosphere on 12 August 2017 and reached 14 km got trapped thereafter within a meso-scale anticyclonic structure which travelled across the Atlantic. It then broke into three offsprings that could be followed until mid-October 2017, each performing  round the world journeys and rising up to 23 km for one of them. We analyze the dynamical structure of the vortices produced by these two wildfires in the ERA 5 and demonstrate how they are maintained by the assimilation of data from instruments measuring the signature of the vortices in the temperature and ozone field. We propose that these vortices can be seen as bubbles of very low potential vorticity carried vertically by their internal radiative heating across the stratosphere against the stratification. We will also present elements of a theory and first numerical simulations explaining the dynamics of such structures  and discuss possible occurrences after other forest fires and volcanic eruptions in the past as well as  future likely impacts. This new phenomenon in geophysical fluid mechanics has, to our knowledge, no reported analog (see reference: https://acp.copernicus.org/preprints/acp-2020-1201/).
Effects of textural layering on water regimes in sandy soils in a desert-oasis ecotone, Northwestern China
Authors: Sun Chengpeng , Zhao Wenzhi , Liu Hu , Zhang Yongyong , Zhou Hong
Published: March 2021

Textural layering of soil plays an important role in distributing and regulating resources for plants in many semiarid and arid landscapes. However, the spatial patterns of textural layering and the potential effects on soil hydrology and water regimes are poorly understood, especially in arid sandy soil environments like the desert-oasis ecotones in northwestern China. This work aims to determine the distribution of textural layered soils, analyze the effects of different soil-textural configurations on water regimes, and evaluate which factors affect soil water infiltration and retention characteristics in such a desert-oasis ecotone. We measured soil water content and mineral composition in 87 soil profiles distributed along 3 transects in the study area. Constant-head infiltration experiments were conducted at 9 of the soil profiles with different texture configurations. The results showed that textural layered soils were patchily but extensively distributed throughout the study area (with a combined surface area percentage of about 84%). Soil water content in the profiles ranged from 0.002 to 0.27 g/cm3 during the investigation period, and significantly and positively correlated with the thickness of a medium-textured (silt or silt loam) layer (P < 0.001). The occurrence of a medium-textured layer increased field capacity (FC) and wilting point (WP), and decreased available water-holding capacity in soil profiles. Burial depth of the medium-textured layer had no clear effects on water retention properties, but the layer thickness tended to. In textural layered soils, smaller water infiltration rate and cumulative infiltration, and shallower depths of wetting fronts were detected, compared with homogeneous sand profiles. The thickness and burial depth of medium-textured layers had obvious effects on infiltration, but the magnitude of the effects depended on soil texture configuration. The revealed patterns of soil textural layering and the potential effects on water regimes may provide new insight into the sustainable management of rainfed vegetation in the desert-oasis ecotones of arid northwestern China and other regions with similar environments around the world.
The Role of Magnetic Reconnection–associated Processes in Local Particle Acceleration in the Solar Wind
Authors: Adhikari Laxman , Zank Gary , Zhao Lingling
Published: March 2021

Recent studies of unusual or atypical energetic particle flux events (AEPEs) observed at 1 au show that another mechanism, different from diffusive shock acceleration, can energize particles locally in the solar wind. The mechanism proposed by Zank et al. is based on the stochastic energization of charged particles in regions filled with numerous small-scale magnetic islands (SMIs) dynamically contracting or merging and experiencing multiple magnetic reconnection in the super-Alfvénic solar wind flow. A first- and second-order Fermi mechanism results from compression-induced changes in the shape of SMIs and their developing dynamics. Charged particles can also be accelerated by the formation of antireconnection electric fields. Observations show that both processes often coexist in the solar wind. The occurrence of SMIs depends on the presence of strong current sheets like the heliospheric current sheet (HCS), and related AEPEs are found to occur within magnetic cavities formed by stream–stream, stream–HCS, or HCS–shock interactions that are filled with SMIs. Previous case studies comparing observations with theoretical predictions were qualitative. Here we present quantitative theoretical predictions of AEPEs based on several events, including a detailed analysis of the corresponding observations. The study illustrates the necessity of accounting for local processes of particle acceleration in the solar wind.
Plasma instabilities driven by pickup ions of ring-beam velocity distributions in the outer heliosheath 
Authors: Mousavi Ameneh , Liu Kaijun , Sadeghzadeh Sina
Published: March 2021

The stability of the pickup ions in the outer heliosheath has been studied by many researchers because of its relevance to the energetic neutral atom (ENA) ribbon observed by the Interstellar Boundary EXplorer. However, previous studies are primarily limited to pickup ions of near 90° pickup angles, the angle between the pickup ion injection velocity and the background, local interstellar magnetic field. Investigations on pickup ions of smaller pickup angles are still lacking. In this paper, linear kinetic dispersion analysis and hybrid simulations are carried out to examine the plasma instabilities driven by pickup ions of ring-beam velocity distributions at various pickup angles between zero and 90°. Parallel propagating waves are studied in the parameter regime where the parallel thermal spread of the pickup ions falls into the Alfvén cyclotron stability gap. The linear analysis results and hybrid simulations both show that the fastest growing modes are the right-hand helicity waves propagating in the direction of the background magnetic field, and the maximum growth rate occurs at the pickup angle of 82°. The simulation results further reveal that the saturation level of the fluctuating magnetic fields for pickup angles below 45° is higher than that for pickup angles above 45°. So, the scattering of pickup ions at near zero pickup angles is likely more pronounced than that at near 90° pickup angles .
Using reflection seismic method to estimate the fluid dynamics parameters related to wakes
Authors: Fan Wenhao , Song Haibin , Zhang Kun , Gong Yi , Yang Shun , Wu Di
Published: March 2021

In this study, when using reflection seismic data to study the wakes of the Batan Islands, a method for estimating the fluid dynamics parameters such as the relative vorticity (relative Rossby number) and the relative potential vorticity is proposed. Although the relative Rossby number estimation method proposed in this study cannot guarantee absolute accuracy in the calculation value, this method is more accurate in describing the positive and negative vorticity distribution for the wakes, and the resolution of the positive and negative vorticity distribution described by this method is higher than the result of the reanalysis data. For the wakes developed in the Batan Islands, the reflection events in the wake development area have the larger inclination than the reflection events in the western Pacific water distribution area. It is also found that the negative vorticity wakes are mainly distributed on the west side of the island/ridge, and the positive vorticity wakes are mainly distributed on the east side of the island/ridge. This is consistent with the understanding of previous wakes simulations. The strong vorticity values in the study area are mainly distributed at depths above 300m, and the maximum impact depth of wakes can reach 600m. At the downstream position of the wake on the survey line 7, it can be seen that the bottom boundary layer has separated, and there is the negative vorticity wakes on the west side intruding into the positive vorticity wakes on the east side , which is presumed to be caused by the disturbance of the small anticyclone existing near the Batan Islands. For the survey line 7, the negative potential vorticity is mainly distributed on the west side of the island/ridge, and the influence range can reach the sea depth of 600m. In the negative potential vorticity region, there is strong energy dissipation and vertical shear. In this study, we don’t find the existence of submesoscale coherent vortices on the survey line 7, but find the reflection structure similar to filaments on the seismic section. Combined with the analysis of the balanced Richardson number angle of survey line 7, we speculate that the wake in the negative potential vorticity distribution area has the characteristics of symmetrical instability, and the symmetrical instability may destroy the process of filaments forming submesoscale coherent vortices.
Understanding the evolution of atmospheric nitrous oxide over the last century from the stable isotopes of the firn air at Styx Glacier, East Antarctica
Authors: Ghosh Sambit , Toyoda Sakae , Ahn Jinho , Jang Youngjoon , Yoshida Naohiro
Published: March 2021

The increase in mixing ratio of greenhouse gas (GHG) has been believed to be the primary driver for the ongoing global warming. Among the GHGs, the mixing ratio of nitrous oxide (N2O) has increased by 23% since 1750 CE. N2O has a long residence time of ca. 120 years, and a potential to destruct the ozone layer. The Global Warming Potential of N2O is about 300 times greater than that of CO2 over 100 years. However, the temporal changes in magnitude and geographic distribution of different N2O sources are uncertain, hence, understanding the dynamics of atmospheric N2O has been a challenge to the researcher during the last few decades. Here, we present new stable isotope data of N2O from the firn air at Styx Glacier, East Antarctica to comprehend the atmospheric evolution for the last 100 years. Our results show that the N2O mixing ratio has increased, whereas the δ15Nbulk (‰, AIR) and δ18O (‰, VSMOW) values decreased during the last 100 years, consistent with the existing firn air records. The progressive increase in the N2O mixing ratio and the decrease in the isotope ratios suggest a higher contribution from the anthropogenic sources assuming that the N2O flux from the natural sources is constant. Our box model analysis using the stable isotopes and mixing ratio data of N2O of Styx firn air suggests that anthropogenic N2O emission at 2014 CE was ca. 37.5% higher than 1919 CE. The box model calculation with Styx and other firn air and ice core data suggests that in comparison to the pre-industrial era, the total N2O emission is ca. 61% higher at present (2014 CE), where ca. 62% and 38% contributions are from natural and anthropogenic sources, respectively to the total N2O emission. The isotope-based mass-balance calculation indicates that continental emission was ca. 45% higher in 2014 CE than in 1919 CE. Although there is a large scatter in existing data, the site preference of 15N in N2O molecules (δ15NSP ‰, AIR) shows an increasing trend during the post-industrial era, which is consistent with the idea that enhanced fertilization increased soil N2O emissions by activating nitrification processes.
Sanitary waste management under Covid-19 restrictions in Ecuador
Authors: Ponce Ochoa Katerine Elizabeth , Rodrigo-Ilarri Javier , Rodrigo-Clavero María-Elena
Published: March 2021

Ecuador, with a population of approximately 17.08 million inhabitants, is one of the most COVID-19 affected countries in the world. On March 16th, 2020, a countrywide state of exception was declared by the national government, therefore applying measures to restrict mobility, suspension of working hours and closure of borders. This situation caused an increase in the massive demand for masks and gloves as the primary ways to preventing infection. These masks and gloves are single-used and discarded, causing an impact on the environment due to the time they take to decompose. In addition, syringes and other hospital may also become infectious waste.

 

Although hospitals may comply the regulations for the management and treatment of hazardous solid waste in Ecuador, the health emergency surprised all hospitals, clinics and health centers due to the increase in patients with coronavirus. This situation led to the establishment of new protocols for this type of waste and also for the management of corpses with COVID-19.

Health personnel are the ones that have been most affected during this time, so they have been working on the front line and have been the most exposed to contagion, increasing the use of disposable masks, gloves and gowns and contributing to the increase of waste from hospitals and health centers.

 

The objective of this study is to investigate and understand how the management of hospital waste has been developed in times of pandemic in the Ecuadorian Institute of Social Security (IESS) Manuel Ignacio Monteros in the city of Loja.

 

To carry out this study, information are taken from the records and databases generated in the IESS about the amount of hospital waste generated during the months of March to December 2020. Results are obtained making comparisons with the amount of hospital waste generated in the previous year 2019. The information was collected through surveys directed both to medical and administrative personnel who were in direct care of COVID-19 managing operations.

 

Results show that a considerable increase in the quantity and characteristics of hospital waste generated during the months of analysis was found. Hazardous hospital waste have been managed correctly as established by various protocols and agreements (Ministerial Agreement 0323) in full compliance with current legislation.
The critical parameters of the human health impact calculation            
Authors: Baranovskaya Natalia , Belyanovskaya Alexandra , Laratte Bertrand , Ageeva Elena
Published: March 2021

There are many LCA methods and models (e.g. CML 1992, Eco-Indicator 95, IMPACT 2002+, TRACI, USEtox, etc.), used to characterize environmental impacts. Only four LCIA methods include spatial dimension at different geographical levels: Impact World+, LC-IMPACT, EDIP 2003 and USEtox (Bratec et al., 2019). Among these, three (Impact World+, EDIP 2003 and USEtox) include a human health impact category: human toxicity. The USEtox model, recommended by the European Commission, has already proved its efficiency for the coupling of environmental and geochemical studies. The Characterization factors of the USEtox describe environmental fate (FF) of the chemicals, their non- and carcinogenic effect (EF), direct and the indirect exposure (XF). All these factors vary depends on the applicable area. However, despite all advantages of the model, its geographical customization is rather generic. This paper presents the utilization of the already published case study (Belyanovskaya et al., 2019: 2020) with the indirect human exposure factor modification. The investigation present the modified biotransfer factor of the metals (Cr, Zn, Sb, As, Ba) of the meat product calculated specifically for different location inside the area “Central Asia”. The paper extends already published results with local data of the city of Vladivostok (Russia).

Acknowledgement

The statistical data processing is supported by State program RF «Science». Project FSWW-0022-2020.

The impact assessment with the USEtox model is supported by the RSF grant (№ 20-64-47021).
Large Scale Exploitation of Satellite Data for the Assessment of Urban Surface Temperatures
Authors: Mitraka Zina , Chrysoulakis Nektarios
Published: March 2021

The rate at which global climate change is happening is arguably the most pressing environmental challenge of the century and it affects our cities. Temperature is one of the most important parameters in climate monitoring and Earth Observation (EO) systems and the advances in remote sensing science increase the opportunities for monitoring the surface temperature from space. The EO4UTEMP project examines the exploitation of EO data for monitoring the urban surface temperature (UST). Large variations in surface temperatures can be observed within a couple of hours, particularly when referring to urban surfaces. The geometric, radiative, thermal, and aerodynamic properties of the urban surface are unique and exert particularly strong control on the surface temperature. EO satellites provide excellent means for mapping the land surface temperature, but the particular properties of the urban surface and the unique urban geometry in combination with the trade-off between temporal and spatial resolution of the current satellite missions impose the development of new sophisticated surface temperature retrieval methods particularly designed for urban areas. EO4TEMP develops a novel UST algorithm exploiting multi-temporal, multi-sensor, multi-resolution EO data, to be validated with in-situ measurements in urban sites and to be applied to Sentinel-3 and Sentinel-2 data. Therefore, EO4UTEMP will provide an advanced methodology for deriving frequent UST estimations at local scale (100 m), capable of resolving the diurnal variation of UST and contribute to the study of the urban energy balance.
Enhancing accuracy and interpretability of machine learning models using super learning and permutation feature importance techniques in digital soil mapping 
Authors: Taghizadeh-Mehrjardi Ruhollah , Hamzehpour Nikou , Hassanzadeh Maryam , Schmidt Karsten , Scholten Thomas
Published: March 2021

The digital soil mapping (DSM) approach predicts soil characteristics based on the relationship between soil observations and related covariates using machine learning (ML) models. In this research, we applied a wide range of machine learning models (12 base learners) to predict and map soil characteristics. To enhance accuracy and interpretability we combined the base learner predictions using super learning strategy. However, a major problem of using super learning and complex models is that the explicit share of individual covariates persons in the overall result cannot be explicitly quantified. To overcome this restriction and make the super learning models interpretable, we employed model-agnostic interpretation tools, for example, permutation feature importance. Particularly, we integrated the weight assigned to each ML base learner obtained by super learning and the ranked ML base learner’s covariates obtained by permutation feature importance to explore the contribution of covariates on the final prediction. We tested our super learning and permutation feature importance techniques to predict and mapping physicochemical soil characteristics of Urmia Playa Lake (UPL) sediments in Iran. As expected, our results indicated that super leaning could significantly improve the ML accuracies for predicting soil characteristics of single base learners. In terms of root mean square error, super learning improved over the performance of the linear regression by an average of 45.7%. Furthermore, the permutation feature importance allowed us to interpret our results better and prove the significant contribution of geomorphological features and groundwater data in predicting soil characteristics of UPL sediments.