bluuebunny/crossref_metadata_2025 huggingface dataset:
Monitoring dissolved radon-222 in groundwater in a volcanic island (Tenerife, Canary Islands)
Authors: Torres González Pedro Antonio , Luengo Oroz Natividad , Pujol Lluis
Published: March 2021

Radon-222, 222Rn, is a naturally radioactive noble gas with a half-life of 3.82 days. It is a product of the 238U disintegration chain with 226Ra as parent isotope. Radon gas has traditionally been linked to magmatic and seismic activity.

In order to improve volcanic surveillance networks, 222Rn monitoring in volcanic areas is carried out by measuring its concentration in air and soils. Also, since radon-222 is soluble in water, the gas may also be dissolved into groundwater flows. The quantity of dissolved 222Rn depends on different factors such as the characteristics of the aquifer, water-rock interaction, water residence time and material content of radium.

In Tenerife there are a vast number of excavated galleries, subhorizontal water mining tunnels, that drain the main aquifer in the island. Thirteen of them have been selected in order to monitor the dissolved radon-222 concentration since October 2019 every three months. This set of galleries surrounds the main volcanic complex in the island, Teide-Pico Viejo, located in Las Cañadas caldera in central Tenerife. 

Before sampling, 10 ml of Opti-Fluor O scintillation cocktail for selective extraction of radon-222, two-phase counting method, was transferred into a 20 ml vial. During the sampling, 10 ml of water were injected into the bottom of the vial. The vial was then tightly capped, vigorously shaken and transported to the laboratory for analysis. Water samples were measured using the liquid scintillation system Quantulus 1220 from PerkinElmer.

In this work, we show the main and preliminary results, which includes both spatial and temporal distribution of the dissolved radon concentration measured in the selected sampling points for the studied period. There are galleries showing a high stability, with radon-222 activity concentrations around 20 Bq/L, whereas others show a clear seasonal influence. The maximum dissolved 222Rn value detected was 29.2 ± 2.1 Bq/L. The detection limit is 0.5 Bq/l using a 30 minutes counting time. Besides, this dataset has been compared to data previously reported by other authors, in order to find changes in dissolved radon-222 emission across time. Finally, in the aim of finding interesting relationships, dissolved 222Rn values have been studied together with in situ groundwater parameters measured in the field (temperature, pH and electric conductivity) and, in some of the sampling points, also with dissolved CO2 concentration and isotopic ratio 3He/4He corrected for air contamination, (R/Ra)c, which are parameters directly related to volcanic activity.
The Australian Plate and underlying mantle from waveform tomography with massive datasets
Authors: de Laat Janneke , Lebedev Sergei , Chagas de Melo Bruna , Celli Nicolas , Bonadio Raffaele
Published: March 2021

We present a new S-wave velocity tomographic model of the Australian Plate, Aus21.  It is constrained by waveforms of 0.9 million seismograms with both the corresponding sources and stations located within the half-hemisphere centred at the Australian continent. Waveform inversion extracts structural information from surface, S- and multiple S-waves on the seismograms in the form of a set of linear equations. These equations are then combined in a large linear system and inverted jointly to obtain a tomographic model of S- and P-wave speeds and S-wave azimuthal anisotropy of the crust and upper mantle. The model has been validated by resolution tests and, for particular locations in Australia with notable differences with previous models, by independent inter-station measurements of surface-wave phase velocities, which we performed using available array data. 

 

Aus21 offers new insights into the structure and evolution of the Australian Plate and its boundaries. The Australian cratonic lithosphere occupies nearly all of the western and central Australia but shows substantial lateral heterogeneity. It extends up to the northern edge of the plate, where it is colliding with island arcs, without subducting. The rugged eastern boundary of the cratonic lithosphere provides a lithospheric definition of the Tasman Line. The thin, warm lithosphere below the eastern part of the continent, east of the Tasman Line, underlies the Cenozoic volcanism locations in the area. The lithosphere is also thin and warm below much of the Tasman Sea, underlying the Lord Howe hotspot and the submerged part of western Zealandia. A low velocity anomaly that may indicate the single source of the Lord Howe and Tasmanid hotspots is observed in the transition zone offshore the Australian continent, possibly also sourcing the East Australia hotspot. Another potential hotspot source is identified below the Kermadec Trench, causing an apparent slab gap in the overlying slab and possibly related to the Samoa Hotspot to the north. Below a portion of the South East Indian Ridge (the southern boundary of the Australian Plate) a pronounced high velocity anomaly is present in the 200-400 km depth range just east of the Australian-Antarctic Discordance (AAD), probably linked to the evolution of this chaotic ridge system.
HEPPA III intercomparison experiment on electron precipitation impacts:  Estimated ionization rates during a geomagnetic active period in April 2010
Authors: Nesse Tyssøy Hilde , Sinnhuber Miriam , Asikainen Timo , Bender Stefan , Clilverd Mark A. , Funke Bernd , van de Kamp Max , Pettit Joshua , Randall Cora , Reddmann Thomas , Rodger Craig J. , Rozanov Eugene , Smith-Johnsen Christine , Sukhodolov Timofei , Verronen Pekka T. , Wissing Jan Maik , Yakovchuk Olesya
Published: March 2021

Precipitating auroral and radiation belt electrons are considered an important part of the natural forcing of the climate system.  Recent studies suggest that this forcing is underestimated in current chemistry-climate models. The HEPPA III intercomparison experiment is a collective effort to address this point. Here, eight different estimates of medium energy electron (MEE) (>30 keV) ionization rates are assessed during a geomagnetic active period in April 2010.  The objective is to understand the potential uncertainty related to the MEE energy input. The ionization rates are all based on the Medium Energy Proton and Electron Detector (MEPED) on board the NOAA/POES and EUMETSAT/MetOp spacecraft series. However, different data handling, ionization rate calculations, and background atmospheres result in a wide range of mesospheric electron ionization rates. Although the eight data sets agree well in terms of the temporal variability, they differ by about an order of magnitude in ionization rate strength both during geomagnetic quiet and disturbed periods. The largest spread is found in the aftermath of the geomagnetic activity.  Furthermore, governed by different energy limits, the atmospheric penetration depth varies, and some differences related to latitudinal coverage are also evident. The mesospheric NO densities simulated with the Whole Atmospheric Community Climate Model driven by highest and lowest ionization rates differ by more than a factor of eight. In a follow-up study, the atmospheric responses are simulated in four chemistry-climate models and compared to satellite observations, considering both the model structure and the ionization forcing.
Detection of irrigated and rainfed crop fields in temperate areas using Sentinel-1, Sentinel-2 and rainfall time series
Authors: Pageot Yann , Baup Frédéric , Inglada Jordi , Demarez Valérie
Published: March 2021

Human activities have an impact on the different components of the hydrosphere and 80 % of the world's population is now facing water shortages that will worsen with global warming. Faced with this emergency situation, it is necessary to develop adaptation strategies to monitor and manage water resources for the entire population and to maintain agricultural activity. One of the adaptation strategies that has been favoured is the management of crop irrigation to optimize the use of scarce water ressources.

To meet this objective, it is necessary to have explicit information on irrigated areas. However, up to now, this information is missing or imprecise at the field scale (it is only produced as aggregated statistics or maps at the regional or national scales). In this work, we propose a method for detecting irrigated and rainfed plots in a temperate areas (Adour-Amont watershed of 1500 km² located in south-western France) jointly using optical (Sentinel-2), radar (Sentinel-1) and rainfall (SAFRAN) time series, through the random forest classification algorithm. This spectral information was synthesized in the form of cumulative monthly indices corresponding to the sum of the spectral information for each element (optical, radar, rainfall). This cumulative approach makes it possible to reduce the redundancy of the spectral information and the calculation time of the classification process.

The summer crops studied were maize, soybean and sunflower, representing respectively 82%, 9% and 8% of the crops cultivated of the studied area, but only part of these crops were irrigated. In order to make the distinction for the same crop, we assume that the speed and amplitude of canopy development differs between irrigated and rainfed crop. Five scenarios were used to evaluate the performance of classification models. They have been built according to the different spatialized data, i.e (Optic; Radar; Optic & Radar; Optic, Radar & Rainfall and 10-day images, which is reference scenario without the cumulative monthly indices). Finally, generated classification maps were evaluated using ground truth data collected during 2 years with contrasted meteorological conditions.

 The use of separate radar and optical data gives low results (Overall Accuracy (OA) < 0.5) compared to the combined classifications of the cumulated data set (optical & radar), which gives good results (OA ± 0.7). The use of the monthly cumulated rainfall allows a significant improvement of the Fscore of the irrigated and rainfed crop classes. Our study also reveals that the use of cumulative monthly indices leads to performances similar to those of the use of 10-day images while considerably reducing computational resources.
Tree-rings δ13C different responses to environmental factors in angiosperms and gymnosperms at global scale
Authors: Li Xiaozhen , Chen Guo , Qin Wenyi , Wang Peng , Wang Xiang
Published: March 2021

Tree-rings, was an extraordinary information base of climate. The global climatic change has been modifying ecosystem, it is important to understand mechanism of how plants respond to climate change. The carbon isotope composition of tree-rings corrected to the value before industrial revolution (δ13Cring) can provide climatic information and carbon and water balance relationship of plants. However, it was still a challenge to disentangle the influence of different environmental parameters on δ13Cring among different tree types. We collected published data of δ13Cring from published papers and study how angiosperms and gymnosperms responsed to different environmental parameters. The results showed that the δ13Cring of angiosperms and gymnosperms were significantly different and there was a decrasing trend in δ13Cring of angiosperms and gymnosperms. In this study, we found that atmospheric concentration (Ca) was not the mainly factor to influence the δ13Cring, and the MAT and PRE were the most important environmental parameters to influence the decreasing trend of δ13Cring for angiosperms and gymnosperms, respectively. Additionally, the global isoscapes of δ13Cring were not established, in this study, three machine learning methods to predict the spatial distribution of δ13Cring were done, the results showed that RF was the best model to established the isoscapes of δ13Cring.
Geodiversity and geotourism for the local people - a study of the Western Carpathians.
Authors: Strus Pawel , Chrobak Anna , Novotny Jan
Published: March 2021

Study of the geodiversity in last decade was very popular in scientific literature. Also the Western Carpathians was the study area for geodiversity and geotourist assessment many times. As part of this study, an attempt was made to answer several questions regarding geodiversity and geotourism in relation to the local inhabitants of the area: 1/Is geodiversity and geotourism in the Western Carpathians able to attract wider crowds of tourists, not only interested specialists? 2/Do people living near a geotourist attraction realize its potential? In addition the authors want to show the summarizing geodiversity map of the Western Carpathians and how much time does the whole procedure of creating a geodiversity map for such a large area as the Western Carpathians take and how much work is required to prepare a study for that region. Important question is also a coherence of the study in a case of the region covering many countries and therefore various character of data available. Secondly, the authors have compared the geodiversity map with the distribution of geosites available in databases of Polish, Slovak and Czech Geological Surveys. This comparison shows that not always the largest number of geosites are located in places with the highest geodiversity index, as it might seem. Finally, the authors present a pilot study of the perception of inanimate nature by local residents that have been carried out in Podtatrze area (Southern Poland/Northern Slovakia). The results show that assumption that local people know their region very well is not entirely true. Most of the inhabitants do not know the basic forms of the relief that occur in the vicinity of their place of residence, cannot correctly recognize the type of rocks that are around them, or are unable to name the peaks that they look at from the window of their house. What could be the reason of it? Perhaps the lack of knowledge about their "little homeland" which they should acquire in primary school; or the simple lack of interest in inanimate nature resulting from the economic lack of profitability vision; or the lack of promotion of the most interesting geotouristic elements in the region. Summing up, the area of the Western Carpathians has areas with a very high and high geodiversity index, which may increase their (geo)tourism potential and constitute a source of additional profit for local residents, but requires access and promotion.
Above Ground Biomass References for Urban Trees from Terrestrial Laser Scanning Data
Authors: Kükenbrink Daniel , Gardi Oliver , Morsdorf Felix , Thürig Esther , Schellenberger Andreas , Mathys Lukas
Published: March 2021

Trees supply a multitude of ecosystem services (e.g. carbon storage, suppression of air pollution, oxygen, shade, recreation etc.) not only in forested areas but also in urban landscapes. Many of these services are positively correlated with tree size and structure. The assessment of carbon storage potential via the quantification of above ground biomass (AGB) is of special importance. However, quantification of AGB is difficult and applied allometries are often based on forest trees, which are subject to very different growing conditions, competition and form compared to urban trees. In this contribution, we highlight the potential of terrestrial laser scanning (TLS) techniques to extract high detailed information on tree structure and AGB with a focus on urban trees.

A total of 55 urban trees distributed over eight cities in Switzerland were measured using TLS and traditional forest inventory techniques before they were felled and weighted. Tree structure, volumes and AGB from the TLS point clouds were extracted using Quantitative Structure Modelling (QSM). TLS derived AGB estimates were compared to allometric estimates dependent on diameter at breast height only. The allometric models were established within the Swiss National Forest Inventory and are therefore optimised for forest trees.

TLS derived AGB estimates showed good performance when compared to destructively harvested references with an R2 of 0.954 (RMSE = 556 kg), compared to an R2 of 0.837 (RMSE = 1159 kg) for allometrically derived AGB estimates. A correlation analysis showed that different TLS derived wood volume estimates as well as trunk diameters and tree crown metrics show high correlation in describing total wood AGB.

The presented results show that TLS based wood volume estimates show high potential to estimate tree AGB independent of tree species, size and form. This allows us to retrieve highly accurate, non-destructive AGB estimates that could be used to establish new allometric equations without the need of extensive destructive harvest.
Stationary Waves and Upward Troposphere-Stratosphere Coupling in Operational Subseasonal Forecasting Models
Authors: Schwartz Chen , Garfinkel Chaim
Published: March 2021

Realistic representation of large-scale stationary waves (SWs) in general circulation models is crucial, as they modulate the trajectories of mid-latitude storms, and shape the distribution of surface temperatures along comparable latitude bands over densely populated areas in the Northern Hemisphere.

In this work, we assess the fidelity of NH wintertime SWs in 5 operational subseasonal-to-seasonal models. In the troposphere, we found that biases in the North Pacific are more pronounced in NCEP, ECMWF and UKMO models compared to the North Atlantic, while in the CMA and BoM models, large biases in amplitude and phase are present in both sectors. These biases in tropospheric SWs directly affect the simulated SWs in the stratosphere.

Finally, we attribute the biases in the North Pacific sector, in part, to the mean state biases in the tropics. Longitudinal shifts in the time-mean tropical convection over the Maritime Continent and central Pacific, affect the longitudinal position of the North Pacific trough in the models.
Refined InSAR landslides deformation monitoring with tropospheric delay correction using multi-temporal moving-window linear model
Authors: Wang Yian , Dong Jie , Zhang lu , Liao Mingsheng , Gong Jianya
Published: March 2021

SAR Interferometry (InSAR) has been proven to be effective for measuring landslides deformation. However, the accuracy of InSAR application of landslide mapping and monitoring is limited by the complex atmospheric distortion in alpine valley areas. The sparse external atmospheric data cannot accurately reflect the complex heterogeneous atmosphere in alpine valley areas. The conventional atmospheric delay corrections based on InSAR phase are weakened by the presence of confounding signals (e.g., tropospheric delays, deformation signals, and topographic errors) and spatial heterogeneity of the troposphere.
In this study, we propose the multi-temporal moving-window linear model to estimate the stratified tropospheric delay. The linear relationship between the multi-temporal interferometric phases and the local terrain is estimated using moving windows and then we retrieve the vertical stratified atmospheric phase over the whole scene. Taking into account the deformation information and phase unwrapping errors, the model is solved by an iterative robust estimation algorithm weighted by both deformation rates and residual unwrapping phases.
 We first compared our model with four other InSAR atmospheric delay correction methods: traditional empirical linear model, REA5 numerical atmospheric model, GACOS, and temporal/spatial filtering method. The results demonstrated that our proposed model has the best performance on atmospheric delay correction over the reservoir of the Lianghekou hydropower station using Sentinel-1 datasets. Meanwhile, our model was less affected by randomly turbulent phase and phase unwrapping errors, which significantly improves the accuracy of landslide deformation detection and monitoring.
Then, we integrated the multi-temporal moving window atmospheric delay correction model into the STAMPS-SBAS program. The high-precision wide-area time series deformation over the reservoir area can be obtained through iterating phase unwrapping and atmospheric delay correction. In particular, the phase unwrapping errors were gradually corrected during the iteration process. The improvement of the proposed model on the landslide investigations was validated through using UAV images and field surveys. Some landslides that have not been identified in the traditional time-series InSAR results can be identified after atmospheric delay correction by the proposed model.
Getting to impact at scale: A dynamic model to guide scaling of climate change education
Authors: Rooney-Varga Juliette , Kapmeier Florian
Published: March 2021

In order to successfully address climate change, society needs education that scales rapidly, transmits scientific information about its causes and effects, and motivates sustained commitment to the problem and science-based action to address it. The gap in public understanding and motivation to address climate change is not caused by a lack of information or educational resources that are effective. Systems thinking and simulation-based learning have been shown to deliver gains in knowledge, affect, and intent to take action and learn more about climate change. But, in order to have impact at scale, an educational innovation must be adopted at scale. Most of the time they are not: uptake from dissemination, active outreach, or word-of-mouth diffusion among educators usually falls short. Here, we describe and apply a simple system dynamics model to explore why propagation efforts often fall flat. We then use the model to explore how rapid scaling could be achieved in higher education. We rely on prior studies and expert opinion for model structure and parameterization. Our analysis shows that outreach has limited impact and does little to accelerate word-of-mouth adoption under conditions typical in higher education. Instead, widespread adoption is fueled by encouraging and supporting adopters’ efforts to reach, persuade, and support potential adopters through community-based propagation. We explore faculty incentives and cultural shifts that could enable community-based propagation.
Comparisons Between E-region Coherent Scatter and Swarm-E Fast Auroral Imager Measurements
Authors: Huyghebaert Devin , McWilliams Kathryn , Hussey Glenn , Howarth Andrew , Erion Stephanie , Rutledge Paige
Published: March 2021

The Ionospheric Continuous-wave E-region Bistatic Experimental Auroral Radar (ICEBEAR) is a VHF coherent scatter radar that makes measurements of the E-region ionosphere with a field of view centered on ≈ 58°N, 106°W.  This overlaps with the Saskatoon SuperDARN radar field of view, providing the opportunity for multi-frequency coherent scatter radar measurements in a similar region.  In conjunction with these coherent scatter radar measurements, the Swarm-E, or e-POP, satellite Fast Auroral Imager (FAI) has been used to make measurements of auroral emissions in the 650-1100 nm wavelength band over the same field of view.  The primary emission species in this wavelength range are N2, O2, and N2+, which correspond to energetic charged particle precipitation penetrating into the lower altitudes of the ionosphere.  This makes the FAI a great instrument for comparison studies with E-region coherent scatter.  In addition to this, the FAI is able to be slewed to a location allowing for extended conjunction windows between the imager and the coherent scatter radars.  With recent advances in radar hardware and processing the temporal and spatial resolutions of these different instruments are becoming comparable (~ 1 s, 1.5 km), providing an excellent opportunity to study plasma density irregularities in the E-region ionosphere in great detail.  Comparisons between the coherent scatter radar and FAI measurements are presented, providing insights into how E-region plasma density irregularities correspond to the location of auroral emissions at 650-1100 nm wavelengths.
GHG mitigation potential of agricultural management practises on mineral and organic soils
Authors: Lind Saara , Maljanen Marja , Myllys Merja , Räty Mari , Kykkänen Sanna , Korhonen Panu , Termonen Maarit , Shurpali Narasinha , Virkajärvi Perttu
Published: March 2021

Agricultural soils are a significant source of greenhouse gas (GHG) emissions. To study these emissions, we are currently building three research platforms that consist of full eddy covariance instrumentation for determination of net ecosystem carbon dioxide exchange and fluxes of methane and nitrous oxide. These platforms will be completed with supporting weather, plant and soil data collection. Two of our platforms are sites on organic soils with a thick peat layer (>60 cm) and the third one is on a mineral soil (silt loam). To study the role of the grassland management practises at these sites, we have initiated ORMINURMI-project. Here, we will characterise the effects of ground water table (high vs. low), crop renewal methods (autumn vs. summer) and plant species (tall fescue vs. red glover grass) on greenhouse gas budgets of grass production. Also effect on yield amount and nutrient quality will be determined. In this presentation, we will present the preliminary data collected at these research platforms and our plans for the use of these data in the coming years.
Energy Structure Analysis of Vorticity Driven by Thermal Gradient in Developing Cumulonimbus Clouds and Application to Data Assimilation
Authors: Ono Akiyuki , Yamaguchi Kosei , Nakakita Eiichi
Published: March 2021

 It is an essential problem for forecasting Mesoscale Convection Systems to understand the mechanism of interaction between atmospheric flow and vortices with the development of cumulonimbus clouds using a numerical weather model. In this research, potential temperature gradient based vorticity which is the expression of baroclinic is obtained to analyze the energy structure of the vorticity field in developing cumulonimbus. First, applying the variational method enables us to obtain a diagnostic equation in which the equation of motion, conservation law of mass, and entropy are considered as constraints. Second, Fourier analysis was performed on the vorticity field in the cross-section of the convective core in the isolated cumulonimbus simulation. The temporal change of the spectrum of the vorticity field indicates that the rotational intensity of potential temperature gradient based vorticity increases at the same time as the degree of baroclinicity increases. It was also found that the same tendency can be seen in the analysis of the vorticity field of developing clouds using the environment of the heavy rainfall event in the Kuma River basin that occurred on July 4, 2020. We are planning to analyze the vorticity field in the cluster of cumulonimbus clouds and consider the difference in the energy structure of the vorticity field due to the difference in model resolution. Third, we conducted the data assimilation experiment assuming the use of vertical vorticity estimated by doppler radar observation. As a result, the change in the potential temperature and vertical wind through the error covariance matrix generates coherent convection in the computations.
The role of structural inheritance on Africa-Eurasia plate boundary evolution and neotectonics in the central Mediterranean sea
Authors: Polonia Alina , Artoni Andrea , Barberi Graziella , Billi Andrea , Gasperini Luca , Palano Mimmo , Sgroi Tiziana , Spampinato Salvatore , Sparacino Federica , Torelli Luigi , Ursino Andrea
Published: March 2021

Africa-Eurasia plate convergence and the retreat of the subducting slab led to the consumption of the Tethys ocean lithosphere, which has now mostly disappeared below or accreted/exhumed within the Alps/Apennines. Slab tearing plays a major role in plate boundary evolution, asthenospheric upwelling, dynamic topography and magmatism. However, the role played by structural inheritance on the Africa plate is not well constrained. Based on seismological, geodetic and marine geophysical data, we analyse the pattern of crustal deformation in the Calabrian Arc and Sicily Channel, two key regions to unravel the complex Africa/Eurasia plate interaction in the central Mediterranean Sea.

The Calabrian Arc subduction-rollback system accommodates Africa/Eurasia plate convergence along thrust faults developing both in the frontal and inner domains of the accretionary wedge. However, the most intriguing and tectonically active features are represented by arc-orthogonal faults deforming the subduction system along a complex strike-slip/transtensional pattern that may have been the source of major earthquakes in the Calabrian Arc. Deformation along the lithospheric transtensional faults is punctuated by buried sub-circular magnetized bodies aligned with Mt. Etna, that were interpreted as serpentinite/mud diapirs intruding the subduction system from the lower plate mantle. These faults are part of the overall dextral shear deformation, resulting from differences in Africa-Eurasia motion between the western and eastern sectors of the Tyrrhenian margin of northern Sicily, and accommodating diverging motions in the adjacent compartments of the Calabrian Arc. To the West, the Sicily Channel is part of the Pelagian block and experienced a lithospheric-scale continental rifting starting from the late Miocene with the development of NW-SE-trending tectonic depressions, bordered by crustal normal faults with variable throws. Our geophysical data, however, show that the most active tectonic feature in the area is a N-S trending and ~220-km-long lithospheric fault system characterized by volcanism, high heat flow and seismic activity. The NW-SE elongated rifting pattern, considered the first order structure in this region, appears currently inactive and sealed by undeformed Pleistocene deposits suggesting a recent change in structural development.

Seismological data show that the lithospheric boundaries present in the Calabrian Arc and Sicily Channel correlate well with spatial changes in the depth distribution of earthquakes and separate regions with different Moho depths and thickness of the seismogenic layer. We propose that these boundaries may represent long-lived inherited Mesozoic discontinuities controlling plate boundary evolution and neotectonics.
Uncertainties in Mass Balance Estimation of the Antarctic Ice Sheet Using Input-output Method
Authors: Lin Yijing , Liu Yan
Published: March 2021

Input-Output method (IOM) is a common method for estimating ice sheet mass balance, which shows ice dynamics in mass loss to analyze the response of ice sheet to climate change. However, compared with the altimetry method and the gravity method, the mass balance estimation using IOM has relatively large uncertainty. Assessing the impact of the uncertainties of each component in IOM on the mass balance estimation is conducive to effectively lowering uncertainty in the Antarctic mass budget estimate but of which there has been little quantitative analysis. We assess the uncertainty in the mass balance due to methodological differences in IOM, compare the differences of surface mass balance (SMB, input) in diverse versions and at different spatial scales, and evaluate the uncertainty in ice discharge (FG, output) due to data uncertainty in ice thickness, ice velocity and grounding line. Results showed that the SMBs at different scales are more divergent than that in different versions, resulting in a variation of 216.7 Gt yr-1 in Antarctica, of which the Antarctic peninsula accounts for 55.1%, followed by East Antarctica. The largest variation in FG due to uncertainty in the location of the grounding line is observed, where a 1 km retreat and a 1 km advance of the Antarctic grounding line would respectively result in FG reductions of 82.8 Gt yr-1 and 272.7 Gt yr-1, which are significant in all regions, with the FG corresponding to a 1 km retreat of grounding line in the islands being closer to the multi-year average SMB of the islands. The difference in Antarctic FG due to different ice thickness products is 124.4 Gt yr-1, consistent with the trend in the thickness of ice shelves, and that due to different ice velocity products is only 18.7 Gt yr-1. Within the same margin of error, systematic errors in ice thickness and ice velocity result in an order of magnitude higher difference of FG than random errors.
Seismotectonic Analysis of the 2017 Moiyabana Earthquake (MW 6.5; Botswana), Insights from field investigations, aftershock and InSAR studies 
Authors: Mulabisana Thifhelimbilu , Meghraoui Mustapha , Midzi Vunganai , Saleh Mohamed , Ntibinyane Onkgopotse , Kwadiba Motsamai Tarzan , Manzunzu Brassnavy , Seiphemo Oarabile , Pule Tebogo , Saunders Ian
Published: March 2021

The 3 April 2017 MW 6.5, Moiyabana (Botswana) earthquake occurred in the continental interior of the African plate and in a seismogenic region previously considered as stable. We analyse the mainshock and aftershock sequence based on a local seismic network and local seismotectonic characteristics. The earthquake rupture geometry is constrained with more than 1,000 aftershocks recorded over a period of three months and from the InSAR analysis of Sentinel-1 images (ascending orbit). The mainshock (25.134 E, 22.565 S; depth 22 ± 3 km) was followed by more than 500 events of magnitude M ≥ 0.8 recorded in April 2017 including the largest aftershock (MW 4.6 on the 5 April 2017). Focal mechanism solutions of the mainshock and aftershocks display predominance of NW-SE trending and NE dipping normal faulting. Stress inversion of focal mechanisms obtained from the mainshock and aftershock database are compatible with a NE-SW extension under normal faulting regime. The InSAR study shows fringes with two lobes with 4 to 6 cm coseismic slip on a NW-SE elongated and 30-km-long surface deformation consistent with the mainshock location and normal faulting mechanism. The modelling of surface deformation provides the earthquake rupture dimension at depth with ~ 1 m maximum slip on a fault plane striking 315°, dipping 45°, -80° rake and with Mo 7.12 1018 Nm Although the seismic strain rate is of low level, the occurrence of the 2017 Moiyabana earthquake, followed by an aftershock sequence in the central Limpopo belt classifies the intraplate region as an active plate interior. 
How are guaranties of quality forged and assessed in flood risk modelling ?
Authors: Barbier Remi , Charpentier Isabelle
Published: March 2021

Models and simulations have become essential elements of water management in catchments (Chong, 2019). This raises the question of confidence in the models. We are interested in the criteria used to judge their quality and the way in which the uncertainties inherent to modelling are taken into account and explained throughout the process. 

Our communication is based on the results of one interdisciplinary research project on modelling developed in the framework of Flood Risk Prevention Plans (FRPP). In a nutshell, FRPPs are regulatory documents elaborated under the responsibility of the State. They are then imposed to local urban planning regulations. Their elaboration is based on the modelling of the flood hazard.

We formulate the problem of trust from the perspective of the State services. The latter entrust consulting firms with the implementation of hazard modeling, which (generally) benefit from a strong asymmetry of skills in their favour. Based on a survey conducted in several government departments, we analyze the practice of ordering, piloting and validating these models. The question posed is the following: "how are guaranties of quality and suitability forged and assessed in flood risk modelling?" We review the different stages of the process, from the writting of the specifications to the final validation of the results, including the multiple interactions throughout the work.  

 

 
Integrating biogeomorphic feedbacks in the coastal zone to bolster coastal resiliency
Authors: Palinkas Cindy , Staver Lorie
Published: March 2021

Living shorelines, defined in this study as narrow marsh fringes with adjacent sills, have been gaining traction as the preferred management strategy to mitigate shoreline erosion. These nature-based features provide the same ecosystem services as natural marshes while protecting coastlines. However, they also are threatened by the same environmental changes (sea-level rise, changing sediment supply) as natural marshes and may change characteristics of adjacent subtidal sediments. This study evaluates the role of plants in both the created marshes of living shorelines and, where present, beds of submersed aquatic vegetation (SAV) in the adjacent subtidal in the effectiveness, impacts, and resiliency of living shorelines over ~10 years in mesohaline Chesapeake Bay. At study sites, there is a net seaward movement of shorelines with living shoreline installation due to construction technique. This movement replaces shallow-water habitat immediately adjacent to the pre-existing shoreline; farther offshore, sedimentological changes vary among sites but do not appear to drive changes in the presence/absence of subtidal SAV. While current accretion rates in the created marshes are greater than local relative sea-level rise, there is evidence that accretion rates increase with marsh age, suggesting that living shorelines are most vulnerable in the first few years after installation. Because nutrient burial is maximized when SAV occur next to living shorelines, a management strategy that considers the subtidal and intertidal as integrated components of the coastal system is needed to optimize co-benefits of coastal protection.
Observational Evidence of Surface Wave‐Generated Strong Ocean Turbulence
Authors: Ma Hongyu , Dai Dejun , Guo Jingsong , Qiao Fangli
Published: March 2021

By using an acoustic Doppler velocimeter mounted on the seabed of the continental shelf of the
northern South China Sea, high frequency velocity fluctuations were measured for 4.5 days. The
turbulent kinetic energy dissipation rate was estimated. During the observation, the strong ocean response
to Typhoon Rammasun was recorded to compare the turbulent characteristics before and during the
typhoon. The results show that the turbulence near the seabed is mainly generated by the tidal current shear
and exhibits a quarter diurnal variation during the period before the typhoon. During the typhoon period,
the dissipation rate ε dramatically increased from 1 × 10−6 to 1 × 10−2 m2 s−3 within a short time, and the
significant wave height and the surface wave orbital velocity showed the same tendency. This finding
suggests that the turbulence is dominantly generated by the surface waves near the seabed.
Seasonal prediction of European Summer Heatwaves
Authors: Prodhomme Chloé , Materia Stefano , Ardilouze Constantin , White Rachel H. , Batté Lauriane , Guemas Virginie , Fragkoulidis Georgios , Garcia Serrano Javier
Published: March 2021

Under the influence of global warming, heatwaves are becoming a major threat in many parts of the world, affecting human health and mortality, food security, forest fires, biodiversity, energy consumption, as well as the production and transportation networks. Seasonal forecasting is a promising tool to help mitigate these impacts on society. Previous studies have highlighted some predictive capacity of seasonal forecast systems for specific strong heatwaves such as those of 2003 and 2010. To our knowledge, this study is thus the first of its kind to systematically  assess the prediction skill of heatwaves over Europe in a state-of-the-art seasonal forecast system. One major prerequisite to do so is to appropriately define heatwaves. Existing heatwave indices, built to measure heatwave duration and severity, are often designed for specific impacts and thus have limited robustness for an analysis of heatwave variability. In this study, we investigate the seasonal prediction skill of summer heatwave propensity in the ECMWF System 5 operational forecast system (SEAS5) by means of several dedicated metrics as well as its added-value compared to a simple statistical model. We are able to show, for the first time, that seasonal forecasts initialized in early May can provide potentially useful information of summer heatwave propensity.
Assessment of a Sand Spit Morphodynamics Under Extreme Flood Events
Authors: Pinho José , Iglesias Isabel , Melo Willian , Bio Ana , Avilez-Valente Paulo , Vieira José , Bastos Luisa , Veloso-Gomes Fernando
Published: March 2021

Spits are landforms that present a complex morphology, which depends on currents, waves, sediment transport, tidal range and anthropic-induced changes. Their position and shape is subject to extreme events like flood river discharges and storms. They can also respond to processes that take place at larger time scales, as plate tectonics, sea level rise or even climatological patterns with teleconnections all over the world, as the well know North Atlantic Oscillation (NAO) or El Niño-Southern Oscillation (ENSO). This is the case of the Douro river mouth sand spit located on the northern coast of Portugal. This naturally dynamic sand spit, which has moved landwards over the past decades, has caused frequent nuisance to navigation, affecting width and depth of the navigation channel. Therefore, a breakwater was constructed in an attempt to stabilise the sand spit and the estuary inlet.

Validated hydrodynamic numerical models (openTELEMAC-MASCARET and Delft3D) of the Douro river estuary have demonstrated ability to accurately describe the estuarine hydrodynamic patterns and water elevation under extreme flood conditions. Model results showed that for higher river flow discharges the sand spit is partially inundated.

In this work a morphodynamic model (Delft3D) of the estuary was implemented to assess both the morphodynamics of the sand spit under extreme events, including the effect of sea level rise due to climate change, and the variation of extreme water levels along the estuary due to spit erosional processes that can occur during flood events.

Preliminary results show that the sand spit will be locally eroded for the higher river flood discharges, forming a two-secondary-channels system, with one channel located near the breakwater’s southern extremity and the other, narrower, near the south bank. Associated with these two channels, two depositional bars will be formed in front of the channels at the coastal platform. However, the inner immersed sand spit will be suffering a sedimentation process for all of the simulated scenarios. This way, neither the river mouth discharge conditions nor the water levels inside the estuary will suffer significant changes according to the simulated scenarios.

These results will be complemented with further analyses considering the sediment size influence, tidal level, storm surge, sea level rise and river flood discharges.

Acknowledgements: To the Strategic Funding UIDB/04423/2020 and UIDP/04423/2020 (FCT and ERDF) and to the project EsCo-Ensembles (PTDC/ECI-EGC/30877/2017, NORTE 2020, Portugal 2020, ERDF and FCT). The authors also want to acknowledge the data provided by EDP and IH.
A real time forecast of the electron fluxes measured by GOES 16
Authors: Boynton Richard , Balikhin Michael , Wei Hualiang
Published: March 2021

A real time system is developed to forecast the electron fluxes measured by GOES R spacecraft. Forecast models are developed using the system identification/machine learning methodology based on Nonlinear Autoregressive Moving Average exogenous (NARMAX) models. NARMAX algorithms use past input-output data to automatically deduce a model of the system. Here, the solar wind parameters are used as inputs and the electron fluxes measured by GOES 16 are used as the outputs to deduce the models. The models are then implemented in a real time forecasting system. The forecasting system uses real time solar wind data from ACE, DSCOVR, and ENLIL, which are then processed into the correct format for the NARMAX models to provide a forecast of the electron fluxes at geostationary orbit. 
Influence of surface water variations on VOD and biomass estimates from passive microwave sensors
Authors: Bousquet Emma , Mialon Arnaud , Rodriguez-Fernandez Nemesio , Prigent Catherine , Wagner Fabien , Kerr Yann
Published: March 2021

Vegetation optical depth (VOD) is a remotely sensed indicator characterizing the attenuation of the Earth's thermal emission at microwave wavelengths by the vegetation layer. At L-band, VOD can be used to estimate and monitor aboveground biomass (AGB), a key component of the Earth's surface and of the carbon cycle. We observed a strong anti-correlation between SMOS (Soil Moisture and Ocean Salinity) L-band VOD (L-VOD) and soil moisture (SM) anomalies over seasonally inundated areas, confirming previous observations of an unexpected decline in K-band VOD during flooding (Jones et al., 2011). These results could be, at least partially, due to artefacts affecting the retrieval and could lead to uncertainties on the derived L-VOD during flooding. To study the behaviour of SMOS satellite L-VOD retrieval algorithm over seasonally inundated areas, the passive microwave L-MEB (L-band Microwave Emission of the Biosphere) model was used to simulate the signal emitted by a mixed scene composed of soil and standing water. The retrieval over this inundated area shows an overestimation of SM and an underestimation of L-VOD. This underestimation increases non-linearly with the surface water fraction. The phenomenon is more pronounced over grasslands than over forests. The retrieved L-VOD is typically underestimated by ~10% over flooded forests and up to 100% over flooded grasslands. This is mainly due to the fact that i) low vegetation is mostly submerged under water and becomes invisible to the sensor; and ii) more standing water is seen by the sensor. Such effects can distort the analysis of aboveground biomass (AGB) and aboveground carbon (AGC) estimates and dynamics based on L-VOD. Using the L-VOD/AGB relationship from Rodriguez-Fernandez et al. (2018), we evaluated that AGB can be underestimated by 15/20Mg ha-1 in the largest wetlands, and up to higher values during exceptional meteorological years. Such values are more significant over herbaceous wetlands, where AGB is ~30 Mg ha-1, than over flooded forests, which have typical AGB values of 150-300 Mg ha-1. Consequently, to better estimate the global biomass, surface water seasonality has to be taken into account in passive microwave retrieval algorithms.
Use of Machine Learning algorithms in evaluating the WRF model parameter sensitivity for the simulation of tropical cyclones
Authors: Harish Baki , Chinta Sandeep , Balaji Chakravarthy , Srinivasan Balaji
Published: March 2021

The Indian subcontinent is prone to tropical cyclones that originate in the Indian Ocean and cause widespread destruction to life and property. Accurate prediction of cyclone track, landfall, wind, and precipitation are critical in minimizing damage. The Weather Research and Forecast (WRF) model is widely used to predict tropical cyclones. The accuracy of the model prediction depends on initial conditions, physics schemes, and model parameters. The parameter values are selected empirically by scheme developers using the trial and error method, implying that the parameter values are sensitive to climatological conditions and regions. The number of tunable parameters in the WRF model is about several hundred, and calibrating all of them is highly impossible since it requires thousands of simulations. Therefore, sensitivity analysis is critical to screen out the parameters that significantly impact the meteorological variables. The Sobol’ sensitivity analysis method is used to identify the sensitive WRF model parameters. As this method requires a considerable amount of samples to evaluate the sensitivity adequately, machine learning algorithms are used to construct surrogate models trained using a limited number of samples. They could help generate a vast number of required pseudo-samples. Five machine learning algorithms, namely, Gaussian Process Regression (GPR), Support Vector Machine, Regression Tree, Random Forest, and K-Nearest Neighbor, are considered in this study. Ten-fold cross-validation is used to evaluate the surrogate models constructed using the five algorithms and identify the robust surrogate model among them. The samples generated from this surrogate model are then used by the Sobol’ method to evaluate the WRF model parameter sensitivity.