bluuebunny/crossref_metadata_2025 huggingface dataset:
Cascading processes of the Vaia storm in the italian Rio Cordon mountain catchment 
Authors: Pellegrini Giacomo , Rainato Riccardo , Martini Lorenzo , Mao Luca , Picco Lorenzo
Published: March 2021

Mountain basins can be affected by Large Infrequent Disturbances (LIDs) that have the power of changing their forest cover and morphological settings, and supplying high amounts of sediments to river networks. The resulting cascading processes are often underestimated although their understanding would improve river management strategies. The recent improvements in the field of sediment transport monitoring and analysis allow to gather a deeper understanding of these long-lasting and complex chains of processes, especially in mountain streams. This contribution aims at investigating the suspended sediment transport exhibited by two recent (summer-autumn 2020) over-bankfull (> 2.3 m3/s) flood events occurred in the Rio Cordon, an alpine basin (5 km2) strongly altered by the Vaia storm (October 2018). This LID blew down 139 trees along the main active channel that were removed by local forest operations after the event, leaving exposed banks and increasing the availability of fine sediment. Two water quality sondes were placed upstream and downstream the windthrow affected area (WAA) to monitor the Suspended Sediment Load (SSL) and quantify the contribution of the WAA in supplying sediments. Water discharge and suspended sediment transport were continuously measured by the two instrumentations, while water samples and direct discharge measurements (salt dilution method) were taken to derive rating curves and calibrate the turbidity meters. Results show that the early September 2020 event (Qmax=2.67 m3/s) produced a SSL = 39.27 t and a SSL increase of +5% between the downstream and upstream cross-section. To this, it was also registered a +44% variation of SS maximum concentration (SSC g/l) which can be ascribed to the contribution of the WWA. The event of October 2020 (Qmax=3.05 m3/s) instead, registered a SSL of 179.22 t and a SSL and SSCmax variation of +334% and +81%, respectively. The preliminary results suggest that the SS is not related to the water discharge but for this reason, further analysis and data collection will be made, also considering rainfall data. However, the ongoing monitoring of this area represents a suitable and promising approach for understanding the cascading processes on the SS dynamics in a mountain basin affected by a LID.
Electron pitch angle diffusion and rapid transport/advection during nonlinear interactions with whistler-mode waves
Authors: Allanson Oliver , Watt Clare , Allison Hayley , Ratcliffe Heather
Published: March 2021

Radiation belt numerical models utilize diffusion codes that evolve electron dynamics due to resonant wave-particle interactions. It is not known how to best incorporate electron dynamics in the case of a wave power spectrum that varies considerably on a 'sub-grid' timescale shorter than the computational time-step Δt, particularly if the wave amplitude reaches high values. Timescales associated with the growth rate, γ, of thermal instabilities are very short, and typically Δt>>1/γ. We use a kinetic code to study electron interactions with whistler-mode waves in the presence of a background plasma with thermally anisotropic components, as frequently occur within the magnetosphere. For low values of anisotropy, thermal instabilities are not triggered and we observe similar results to those obtained in Allanson et al. (2020, https://doi.org/10.1029/2020JA027949), for which the diffusion matched the quasilinear theory over short timescales inversely proportional to wave power. For high levels of anisotropy, wave growth via instability is triggered. Dynamics are not well described by the quasilinear theory when calculated using the average wave power. During the growth phase (~0.1s) we observe strong diffusive and advective components, which both saturate as the wave power saturates at ~ 1nT. The advective motions dominate over the diffusive processes. The growth phase facilitates significant transport in electron pitch angle space via successive resonant interactions with waves of different frequencies. This motivates future work on the longer-time impact of very short timescale processes in radiation belt modelling, and on the indirect effects of anisotropic background plasma components on electron scattering. We suggest that this rapid advective transport during nonlinear wave growth phase may have a role to play in the electron microburst mechanism.

[Allanson et al, JGR Space Physics, 2021 (under review)]
A relocatable ocean modelling platform for downscaling to shelf-coastal areas to support disaster risk reduction
Authors: Trotta Francesco , Federico Ivan , Pinardi Nadia , Coppini Giovanni , Causio Salvatore , Jansen Eric , Iovino Dorotea , Masina Simona
Published: March 2021

High-impact ocean weather events and climate extremes can have devastating effects on coastal zones and small islands. Marine Disaster Risk Reduction (DRR) is a systematic approach to such events, through which the risk of disaster can be identified, assessed and reduced via direct observations, thus improving ocean and atmosphere prediction models and the development of efficient early warnings systems. A common user request during disaster remediation actions is for high-resolution information, which can be derived from easily deployable numerical models nested into operational larger-scale ocean models.

The Structured and Unstructured Relocatable Ocean Model for Forecasting (SURF) has been designed to provide operational ocean forecasting communities with the means to rapidly deploy a nested high-resolution numerical model into larger-scale ocean forecasts. Rapidly downscaling the current, sea level and temperature, and salinity fields is critical in supporting emergency response and DRR planning, which are typically related to very localized areas in the world’s oceans. The first and most important requirement in a relocatable modelling capability is to ensure all of the interfaces have been tested through low-resolution operational ocean analyses, forecasts and atmospheric forcing. The provision of continuous ocean circulation forecasts through the Copernicus Marine Environment Monitoring Service (CMEMS) enables this testing. High-resolution SURF ocean circulation forecasts can then be accessed through specific numerical application model interfaces that require the knowledge of meteo-oceanographic conditions, such as oil spill forecasting, search and rescue modelling, and ship routing modelling for safe navigation.

SURF was used to downscale CMEMS circulation analyses in four world ocean regions, and the high-resolution currents it can simulate for specific applications are examined. The SURF downscaled circulation fields show that the marine current resolutions affect the quality of the application models to be used for assessing disaster risks, particularly near coastal areas where the coastline geometry must be resolved through a numerical grid, and high-frequency coastal currents must be accurately simulated.
Increased ocean heat transport into the Nordic Seas and Arctic Ocean over the period 1993-2016
Authors: Tsubouchi Takamasa , Våge Kjetil , Hansen Bogi , Larsen Karin , Østerhus Svein , Johnson Clare , Jónsson Steingrímur , Valdimarsson Héðinn
Published: March 2021

Warm water of subtropical-origin flows northward in the Atlantic Ocean and transports heat to high latitudes. This poleward heat transport has been implicated as one possible cause of the declining sea ice extent and increasing ocean temperatures across the Nordic Seas and Arctic Ocean, but robust estimates are still lacking. Here we use a box inverse model and over 20 years of volume transport measurements to show that the mean ocean heat transport was 305±26 TW for 1993-2016. A significant increase of 21 TW occurred after 2001, which is sufficient to account for the recent accumulation of heat in the northern seas. Therefore, ocean heat transport may have been a major contributor to climate change since the late 1990s. This increased heat transport contrasts with the Atlantic Meridional Overturning Circulation (AMOC) slowdown at mid-latitudes and indicates a discontinuity of the overturning circulation measured at different latitudes in the Atlantic Ocean.
Improved FAIR Data Publication Quality in Specialized Environmental Data Portals
Authors: Iosifescu Enescu Ionut , Plattner Gian-Kasper , Espona Pernas Lucia , Haas-Artho Dominik , Buchholz Rebecca
Published: March 2021

Environmental research data from the Swiss Federal Research Institute WSL, an Institute of the ETH Domain, is published through the environmental data portal EnviDat (https://www.envidat.ch). EnviDat actively implements the FAIR (Findability, Accessibility, Interoperability and Reusability) principles and offers guidance and support to researchers throughout the research data publication process.

WSL strives to increase the fraction of environmental data easily available for reuse in the public domain. At the same time, WSL facilitates the publication of high-quality environmental research datasets by providing an appropriate infrastructure, a formal publication process and by assigning Document Object Identifiers (DOIs) and appropriate citation information.

Within EnviDat, we conceptualize and implement data publishing workflows that include automatic validation, interactive quality checks, and iterative improvement of metadata quality. The data publication workflow encompasses a number of steps, starting from the request for a DOI, to an approval process with a double-checking principle, and the submission of the metadata-record to DataCite for the final data publication. This workflow can be viewed as a decentralized peer-review and quality improvement process for safeguarding the quality of published environmental datasets. The workflow is being further developed and refined together with partner institutions within the ETH Domain.

We have defined and implemented additional features in EnviDat, such as (i) in-depth tracing of data provenance through related datasets; (ii) the ability to augment published research data with additional resources which support open science such as model codes and software; and (iii) a DataCRediT mechanism designed for specifying data authorship (Collection, Validation, Curation, Software, Publication, Supervision).

We foresee that these developments will help to further improve approaches targeted at modern documentation and exchange of scientific information. This is timely given the increasing expectations that institutions and researchers have towards capabilities of research data portals and repositories in the environmental domain.
The South Asia Monsoon Break Promotes Grass Growth on the Tibetan Plateau
Authors: Ren Yanghang , Yang Kun , Wang Han
Published: March 2021

As region that is highly sensitive to global climate change, the Tibetan Plateau (TP) experiences an intra-seasonal soil water deficient due to the reduced precipitation during the South Asia monsoon (SAM) break. Few studies have investigated the impact of the SAM break on TP ecological processes, although a number of studies have explored the effects of inter-annual and decadal climate variability. In this study, the response of vegetation activity to the SAM break was investigated. The data used are: (1) soil moisture from in situ, satellite remote sensing and data assimilation; and (2) the Normalized Difference Vegetation Index (NDVI) and Solar-Induced chlorophyll Fluorescence (SIF). We found that in the region impacted by SAM break, which is distributed in the central-eastern part of TP, photosynthesis become more active during the SAM break. And temporal variability in the photosynthesis of this region is controlled mainly by solar radiation variability and has little sensitivity to soil moisture. We adopted a diagnostic process-based modeling approach to examine the causes of enhanced plant activity during the SAM break on the central-eastern TP. Our analysis indicates that active photosynthetic behavior in the reduced precipitation is stimulated by increases in solar radiation absorbed and temperature. This study highlights the importance of sub-seasonal climate variability for characterizing the relationship between vegetation and climate.
`Flowonthego' - flow tracking technology on your smartphone 
Authors: Higham Jonathan , Plater Andrew
Published: March 2021

Over the past few years, smartphone devices have become so powerful that in your pocket, not only do you have a device which can communicate with people across the world, the sheer power of these devices has now also brought a new frontier in scientific measurements. In this presentation, we present our smartphone app 'flowonthego', a technology which allows users to determine flow velocities, in almost real-time, from simple video footage. The instantaneous velocity fields are calculated by solving the Lucas-Kanade solutions to the optical flow equations and tracking naturally occurring features. The app also harnesses the potential of augmented reality, making calibration reference and the need tape measures a thing of the past. Furthermore, the app also packs an arsenal of post-processing tools in which users can understand basic statistics. From preliminary our studies we have found 'flowonthego' is able to match the statistics of commonly used ADCP's while also providing instantaneous full vector fields allowing users to better understand dynamical processing. 
The Energetic Particle Detector (EPD) Electron-Proton Telescope (EPT) on Solar Orbiter: In-flight calibration and background correction of science data.
Authors: Pacheco Daniel , Kollhoff Alexander , Wimmer-Schweingruber Robert F. , von Forstner Johan L. Freiherr , Terasa Christoph , Elftmann Robert , Boden Sebastian , Berger Lars , Eldrum Sandra , Xu Zigong , Rodríguez-Pacheco Javier , Ho George , Gómez-Herrero Raúl ,   The EPD Team
Published: March 2021

Solar Orbiter was launched in February 2020 carrying the most complete set of in-situ and remote sensing instruments, for the study of the Sun and the heliosphere. The Energetic Particle Detector (EPD) on board of Solar Orbiter was switched on on 28 February 2020 and, since then, it has provided us with measurements of the energetic particles traveling through the inner heliosphere. The EPD suite is composed of a set of different sensors measuring electrons, protons and ions in a wide range of energies.

The Electron-Proton Telescope (EPT) was designed to measure electrons and ions with energies of 35-4000keV and 45-7000keV respectively. By utilizing the so-called magnet/foil-technique, EPT is capable of measuring energetic particles with a high temporal and energy resolution while obtaining directional information from its four different fields of view. Although EPT is well suited for the study of solar energetic particle events, instrumental effects such as the contamination of EPT data products by GCR particles need to be understood for a correct interpretation of the data.

We will present our current understanding of the background and calibration of EPT based on the data gathered during the first year of Solar Orbiter’s mission.
Preliminary results of relative radiometer to measure the Earth’s outgoing radiation on FY-3F satellite
Authors: Wu Duo , Zhu Ping , Fang Wei , Ye Xin , Wang Kai , Jia Ruidong , Xia Zhiwei , Yang Dongjun , Zhao Cong
Published: March 2021

A space based relative radiometer has been developed and applied to the PICARD mission. It has successfully measured 37 months solar radiation, terrestrial outgoing radiation, and a comparable interannual variation in Earth Radiation Budget (ERB) is inferred from those measurements [1]. However, since the BOS (Bolometric Oscillation Sensor [2]) relative radiometer is originally designed to measure the solar irradiance with 10 seconds high cadence comparing to the absolute radiometer. The high dynamic range of BOS limits its performance to track the Earth’s outgoing radiation in terms of instantaneous field-of-view (iFOV) and the absolute radiation level. Two relative radiometers (RR) will be developed for JTSIM/FY-3F. One is the solar channel relative radiometer aimed to measure the solar irradiance side by side with the cavity solar irradiance absolute radiometer (SIAR). The second RR is acting as a non-scanner instrument to measure the Earth’s outgoing radiation. Comparing to the design of PICRD-BOS. Each RR has included an aperture, for the solar channel it limits its Unobstructed Field of View (UFOV) to about 1.5 degree and for the Earth channel to about 110 degrees, respectively. We also test the possibility to use the Carbon Nanotube coating on the main detector. In this presentation, the design of the earth channel relative radiometer (ERR) will be introduced, including the aperture design, dynamic range and the active temperature control system. The preliminary laboratory test result of the ERR will be discussed in the end.

[1] P. Zhu, M. Wild, M. van Ruymbeke, G. Thuillier, M. Meftah, and Ö. Karatekin. Interannual variation of global net radiation flux as measured from space. J. Geophys. Res. doi:10.1002/2015JD024112, 121:6877–6891, 2016.

[2] P. Zhu, M.van Ruymbeke, Ö. Karatekin, J.-P.Noël, G. Thuillier, S. Dewitte, A. Chevalier, C. Conscience, E. Janssen, M. Meftah, and A. Irbah. A high dynamic radiation measurement instrument: the bolometric oscillation sensor (bos). Geosci. Instrum. Method. Data Syst., 4,89-98,:doi:10.5194/gi–4–89–2015, 2015.

Acknowledgement: this work is partly supported by the National Natural Science Foundation of China No. 41974207 and CSC Scholarship No.202004910181

 
Source Parameter Sensitivity of Earthquake Simulations assisted by Machine Learning 
Authors: Monterrubio-Velasco Marisol , Carrasco-Jimenez J. Carlos , Rojas Otilio , Rodriguez Juan E. , Modesto David , de la Puente Josep
Published: March 2021

After large magnitude earthquakes have been recorded, a crucial task for hazard assessment is to quickly estimate Ground Shaking (GS) intensities at the affected region. Urgent physics-based earthquake simulations using High-Performance Computing (HPC) facilities may allow fast GS intensity analyses but are very sensitive to source parameter values. When using fast estimates of source parameters such as magnitude, location, fault dimensions, and/or Centroid Moment Tensor (CMT), simulations are prone to errors in their computed GS. Although the approaches to estimate earthquake location and magnitude are consolidated, depth location estimates are largely uncertain. Moreover, automatic CMT solutions are not always provided by seismological agencies, or such solutions are available at later times after waveform inversions allow the determination of moment tensor components. The uncertainty on these parameters, especially a few minutes after the earthquake has been registered, strongly affects GS maps resulting from simulations.

In this work, we present a workflow prototype to produce an uncertainty quantification method as a function of the source parameters. The core of this workflow is based on Machine Learning (ML) techniques. As a study case, we consider a domain of 110x80 km centered in 63.9ºN-20.6ºW in Southern Iceland, where the 17 best-mapped faults have hosted the historical events of the largest magnitude. We generate synthetic GS intensity maps using the AWP-ODC finite-difference code for earthquake simulation and a one-dimensional velocity model, with 40 recording surface stations. By varying a few source parameters (e.g. event magnitude, CMT, and hypocenter location), we finally model tens of thousands of hypothetical earthquakes. Our ML analog will then be able to relate GS intensity maps to source parameters, thus simplifying sensitivity studies.

Additionally, the results of this workflow prototype will allow us to obtain ML-based intensity maps a few seconds after an earthquake occurs exploiting the predictive power of ML techniques. We will evaluate the accuracy of these maps as standalone complements to GMPEs and simulations.
Simulation of the meander cut-off by 2D hydrodynamic model for erodible bed
Authors: Fedorova Tatiana , Belikov Vitaly , Alabyan Andrei
Published: March 2021

The retrospective simulation of the Pyoza river (Arkhangelsk region, Russia) meander cut-off in 2003-2008 has been undertaken. As a result of the river bend straightening two large villages were cut off from the road network of the region.

The initial data for modeling were obtained by analyses of archive satellite images for the period from 1997 together with the runoff data, as well as by the field survey of September 2019. The simulation was performed by the latest version of the STREAM_2D CUDA software, using a new method for the numerical solution of two-dimensional Saint-Venant equations [1]. It was adapted for the complicated bottom topography typical for a wide floodplain with a meandering channel flooded in high water stage.

The mass-exchange equations for three layers of sediment over the unerodible bed were solved together with the hydrodynamic equations. When calculating channel deformations, the gravitational effect due to bottom slope and the influence of secondary currents on the sediment shift were taken into account [2].

The Pyoza river is the lowest large tributary of the Mezen’ river flowing into the White sea. It is distinguished by a typical alluvial channel, meandering along wide floodplain composed by sands and sandy loams. The maximum runoff usually corresponds to spring snow-melting and can reach 1500-2000 m3/s.

To schematize the computational domain of the Pyoza river section of 13 km long, a hybrid grid of irregular structure was constructed, consisting of 37 329 cells of a quadrangular shape for the channel and a triangular one for the floodplain.

The simulation started at the year 1997 when where was no any rill across the meander neck. The time step of calculation was taken to be one day.

Modeling made it possible to simulate realistically the essential steps and mechanisms of the meander cut-off: the development of a pioneer straightening rill, its widening and deepening, as well as blocking of the old channel by a point bar in its upper reaches, as well as its further silting and aggradation.

1. Aleksyuk A.I., Belikov V.V. (2017): Simulation of shallow water flows with shoaling areas and bottom discontinuities. Computational Mathematics and Mathematical Physics, Volume 57, issue 2, pp. 318–339. https://doi.org/10.1134/S0965542517020026

2. Aleksyuk А. I., Belikov V. V., Borisova N. M., Fedorova T. A. (2018): Numerical modeling of non-uniform sediment transport in river channels. Water Resources, Volume 45, Special Issue S1, pp. 11–17. http://dx.doi.org/10.1134/S0097807818050275
Investigating the spatial heterogeneity of abrupt cooling events during the Lateglacial Interstadial in Britain and Ireland using chironomids and oxygen-isotopes. 
Authors: Francis Christopher , Candy Ian , engels Stefan , Matthews Ian , Palmer Adrian
Published: March 2021

The Windermere Interstadial (GI-1; c. 14.7-12.9 kyr ago), a relatively warm period at the end of the last glaciation, provides an excellent opportunity to study past abrupt cooling events (ACEs). These events, commonly known as GI-1d and GI-1b, are clearly expressed in the Greenland ice cores and offer some of our best analogues for future events caused by anthropogenic warming. Such ACEs have variable expression in terms of their magnitude across Europe and the North Atlantic region which is likely to reflect the forcing factors which drive them. However, relatively few, spatially uneven, quantitative temperature reconstructions of ACEs exist for NW Europe. Between-site differences in sampling resolution applied and calibration datasets used makes inter-comparisons problematic.

 

We applied chironomid and oxygen-isotope analysis at a high temporal resolution (~decadal) to a number of Windermere Interstadial lake sequences from spatially diverse locations across the British Isles. This dual proxy approach allows for quantitative reconstructions of past climate change and provides insight into seasonal temperature change as well as hydrological regime shifts. Several chironomid calibration datasets were tested to ascertain which provided the most reliable reconstruction. Even across a relatively restricted area such as the British Isles, clear spatial patterns can be observed in ACE strength. GI-1d exhibits greatest magnitude in the North of the region whilst GI-1b is most strongly expressed in the South. The results highlight the pivotal location of the British Isles in further refining our understanding of the forcing mechanism driving ACEs.
Building cyberinfrastructure systems to support integrative, macroscale analyses of sedimentary ancient DNA records: current resources, needs, and opportunities
Authors: Williams John ,   Cyberinfrastructure for Ancient Sedimentary DNA Working Group
Published: March 2021

The number and extent of ancient DNA records from sedimentary environments (sedaDNA) is rapidly increasing, which creates new opportunities for integrative and macroscale investigations into past population, community, and environmental dynamics at unprecedented taxonomic resolution and spatiotemporal extent.  However, fully achieving this potential requires a robust cyberinfrastructure that supports the joint analysis of many sedaDNA records with each other and with genomic reference libraries, the latest geochronological controls and age-depth models, complementary paleoecological and paleoenvironmental proxies, and the most recent and updated DNA reference library for taxonomic identifications.  Any cyberinfrastructure for macroscale data synthesis must address the variety of ancient DNA records (e.g. taxonomic groups, analytical approaches, depositional contexts) and leverage existing resources and standards such as the Neotoma Paleoecology Database, the MGnify and MG-RAST resources for environmental genomics, and the MixS standard for genetic sequences.  In response, a Cyberinfrastructure for Ancient Sedimentary DNA working group has been meeting regularly since summer 2020 to assess the current state of science and informatics, assess needs and gaps, and establish recommendations for next steps forward.  An initial survey found over 420  sites worldwide with published or in-development sedaDNA records, with greatest densities in Eurasia.  Metabarcoding records, including Amplicon Sequence Variant data and derived taxonomic inferences, are a top priority for trial uploads to Neotoma, with pilot uploads underway, because of the relatively small dataset volumes, the widespread application of metabarcoding assays, and potential of integrating these records with other paleoecological data holdings in Neotoma and linked paleodata resources such as Linked Earth and paleoclimatic data at NOAA’s National Centers for Environmental Informatics.  Because taxonomic inferences are heavily conditioned by choice of bioinformatics pipeline and reference databases, a major unmet need is a repository for minimally processed output from raw sequences.  In general, no existing genomics or paleoecological resource meets all needs of the sedaDNA community, although each covers key elements, so there is a good potential of advancing macroscale data syntheses by leveraging and linking existing resources.
Physics-Based Estimates of the Maximum Magnitude of Induced Earthquakes in the Groningen Gas Field
Authors: Weng Huihui , Ampuero Jean-Paul , Buijze Loes
Published: March 2021

The induced seismicity in the Groningen gas field, The Netherlands, has led to intense public concerns and comprehensive investigations. One of the main challenges for assessing future seismic hazard in the Groningen gas field is to estimate the maximum possible earthquake magnitude (Mmax) that could be induced by gas extraction. Previous methods are strongly rooted in empirical and statistical approaches that are inherently limited by the scarcity of data. Here, we combine a physics-based dynamic rupture model based on the 3D theory of fracture mechanics with field-based and lab-based constraints to estimate Mmax in the Groningen gas field. If earthquakes in the reservoir have a rupture depth extension constrained by the reservoir thickness, the largest earthquakes should develop a large aspect ratio (longer horizontally than vertically). The model is thus an extension of the 3D theoretical rupture model on long faults with uniform stress and strength developed by Weng & Ampuero (2019), in which we have incorporated spatial heterogeneities, such as along-strike variable fault width, depth-dependent initial stresses and friction properties. The essential parameters that control rupture propagation and earthquake magnitude are the stored elastic energy and the fracture energy. Our method requires estimates of the stored elastic energy on reservoir faults as a result of the stresses induced by differential reservoir compaction during depletion. The fracture energy is constrained by laboratory experiments and theoretical frictional models. Coupling physics-based rupture models with field and lab observations provides an estimate of Mmax in the Groningen gas field and serves as a practical step toward physics-based seismic hazard assessment for other gas fields in the world.

 

Citation:

Weng, H. and J. P. Ampuero (2019). "The Dynamics of Elongated Earthquake Ruptures." Journal of Geophysical Research: Solid Earth.
Extension of the repro3 ANTEX file with BeiDou and QZSS satellite antenna pattern
Authors: Villiger Arturo , Dach Rolf , Prange Lars , Jäggi Adrian
Published: March 2021

During the preparations for the International GNSS Service (IGS) contribution to the next reference frame, called repro3, the disclosed pre-launch chamber calibrated Galileo satellite antenna pattern were analyzed. Those tests revealed a discrepancy between the GPS and GLONASS z-component of the phase center offsets (PCO), aligned to the IGS14 scale, and the calibrated Galileo z-PCOs. In order to make the PCOs compatible to the repro3 it was decided to rely on the calibrated Galileo pattern and adjust the GPS and GLONASS PCOs accordingly. Combined with multi-GNSS receiver calibrations for all systems the repro3 might contribute to the scale determination for the next reference frame.

As the repro3 is based on GPS, GLONASS, and Galileo only those three systems have been analyzed leading to the repro3 ANTEX file, containing all used antenna pattern, which is aligned to the Galileo induced scale. In order to extend the repro3 ANTEX file with satellite calibrations for BeiDou and QZSS a dedicated reprocessing based on CODEs MGEX solution is made to assess the available PCOs for those satellites and tests their consistency with the repro3 scale. The results should allow to extend the repro3 ANTEX with the BDS and QZSS pattern for experimental purposes.
The solar wind angular-momentum flux observed during Solar Orbiter's first orbit
Authors: Verscharen Daniel , Stansby David , Finley Adam , Owen Christopher , Horbury Timothy , Velli Marco , Bale Stuart , Louarn Philippe , Fedorov Andrei , Bruno Roberto , Livi Stefano , Lewis Gethyn , Anekallu Chandrasekhar , Kelly Christopher , Watson Gillian , Kataria Dhiren , O'Brien Helen , Evans Vincent , Angelini Virginia
Published: March 2021

The Solar Orbiter mission is currently in its cruise phase, during which the spacecraft's in-situ instrumentation measures the solar wind and the electromagnetic fields at different heliocentric distances. 

We evaluate the solar wind angular-momentum flux by combining proton data from the Solar Wind Analyser (SWA) Proton-Alpha Sensor (PAS) and magnetic-field data from the Magnetometer (MAG) instruments on board Solar Orbiter during its first orbit. This allows us to evaluate the angular momentum in the protons in addition to that stored in magnetic-field stresses, and compare these to previous observations from other spacecraft. We discuss the statistical properties of the angular-momentum flux and its dependence on solar-wind properties. 

Our results largely agree with previous measurements of the solar wind’s angular-momentum flux in the inner heliosphere and demonstrate the potential for future detailed studies of large-scale properties of the solar wind with the data from Solar Orbiter.
Predicting change in biogeochemical potential of subsurface systems with changing hydrogeological conditions
Authors: Khurana Swamini , Heße Falk , Thullner Martin
Published: March 2021

In a changing climate scenario, we expect weather event patterns to change, both in frequency and in intensity. The subsequent impacts of these changing patterns on ecosystem functions are of great interest. Water quality particularly is critical due to public health concerns. Already, seasonal variation of water quality has been attributed to varying microbial community assemblages and nutrient loading in the corresponding water body but the contribution of the variations in the quantity of groundwater recharge is a missing link. It is thus beneficial to establish links between external forcing such as changing infiltration rate or recharge on nutrient cycling in the subsurface. We undertake this study to investigate the impact of temporal variation in external forcing on the biogeochemical potential of spatially heterogeneous subsurface systems using a numerical modeling approach. We used geostatistical tools to generate spatial random fields by considering difference combinations of the variance in the log conductivity field and the anisotropy of the domain. Tuning these two parameters assists in effective representation of a wide variety of geologic materials with varying intensity of preferential flow paths in the heterogeneous domain. We ran simulations using OGS#BRNS that enables us to combine a flexibly defined microbial mediated reaction network with the mentioned spatially heterogeneous domains in transient conditions. We propose that a combination of estimated field indicators of Damköhler number, Peclet number (transformed Damköhler number: Dat), and projected temporal dynamics in surface conditions can assist us in predicting the change in biogeochemical potential of the subsurface system. Preliminary results indicate that we miss potentially critical variations in reactive species concentration if we neglect spatio-temporal heterogeneities for regimes where 1<Dat<40. For regimes characterized by values outside this range, we propose that spatio-temporal heterogeneities due to subsurface structure and changing hydrological forcing may not be relevant.
Global, high-resolution statistical modelling of NO2
Authors: Lu Meng , Schmitz Oliver , de Hoogh Kees , Hystad Perry , Knibbs Luke , Kai Qin , Karssenberg Derek
Published: March 2021

High spatial resolution (<100m) mapping of NO2 at various temporal scales (e.g., hours of the week, month, or year) provides opportunities to study the relationship between personal air pollution exposure and health over large populations. Statistical modelling of NO2 at the global scale provides high-resolution estimations for countries with deficient ground station measurements and provides air pollution maps and human exposures with consistent uncertainties for global health studies. Our objective is to develop spatiotemporally-resolved statistical learning models, understand the temporal dynamics of NO2 and the contributing sources, and open-source our global NO2 prediction maps at 100 m resolution. The global maps are provided at various temporal aggregations (e.g. separating between weekdays and weekends, day and night) and spatial aggregations (e.g. multiple gridded resolutions, administrative units) to facilitate global exposure assessment. To create these maps, we compiled from multiple sources a dataset of hourly NO2 measurements from more than 7000 ground stations over the globe, considerably larger in size and spatiotemporal coverage than used in recent high-resolution NO2 mapping studies. For statistical modelling, geospatial predictors include Sentinel-5 satellite (Tropomi instrument) measurements, variables relating to the emission sources (e.g., road network), dispersion processes (e.g., meteorological variables), elevation and Earth nightlights (from VIIRS nightlight data). We evaluate various statistical models including linear models, ensemble tree-based models, deep convolution models, stacked models with regularisation, and hierarchical modelling strategies and select the optimal model for mapping. Evaluation of models included uncertainty assessment as well as spatial validation methods.
Hydrological resilience to forest fire in the subarctic Canadian Shield
Authors: Spence Christopher , Hedstrom Newell , Tank Suzanne , Quinton William , Olefeldt David , Goodman Stefan , Dion Nicole
Published: March 2021

Forest fires are becoming more frequent and larger in the subarctic Canadian Shield, so understanding the effect of fire on catchment scale water budgets is becoming increasingly important.  The objective of this study was to determine the water budget impact of a forest fire that partially burned a ~450 km2 subarctic Canadian Shield basin.  Water budget components were measured in a pair of catchments; one burnt and another unburnt. Burnt and unburnt areas had comparable net radiation, but ground thaw was deeper in burned areas.  Snowpacks were deeper in burns. Differences in streamflow between the catchments were within measurement uncertainty.  Enhanced winter streamflow from the burned watershed was evident by icing growth at the streamflow gauge location, which was not observed in the unburned catchment.  A new framework to assess hydrological resilience to forest fire across the region revealed that watersheds with higher bedrock and open water fractions are more resilient to hydrological change after fire in the subarctic shield, and resilience decreases with increasingly wet conditions.  
Accelerated warming in the northern midlatitude summer since the 1990s
Authors: Teng Haiyan , Leung Ruby , Branstator Grant , Lu Jian , Ding Qinghua
Published: March 2021

The northern midlatitude summer has experienced rapid warming since the 1990s, especially in Europe, Central Siberia-Mongolia, the West Coast of North America as well as several continental Arctic regions. These “hot spots” are connected by a chain of high-pressure ridges from an anomalous wavenumber-5 Rossby wave train in the upper troposphere.  Here by cross-examining reanalysis datasets and a suite of Coupled Model Intercomparison Project Phase 6 (CMIP6) baseline experiments, we demonstrate that the anthropogenically forced response may be intertwined with internal multidecadal variability, making it difficult to partition the 1979-2020 trend with state-of-the-art climate models. Instead, we take a “storyline” approach with a planetary wave model and sensitivity experiments with an Earth system model to explore key underlying driving factors. Our results highlight the importance of multiscale interaction with synoptic eddy via atmosphere-ocean and atmosphere-land coupling in shaping the multidecadal regional warming trend which has enormous socioeconomic implications. 
Brazilian aviation nowcasting system: current stage and some results
Authors: Almeida Vinícius , França Gutemberg , Albuquerque Neto Francisco , Campos Velho Haroldo , Almeida Manoel , Menezes Wallace , Menegussi Caroline , Cordeiro Fabricio
Published: March 2021

Emphasizes some aspects of the aviation forecasting system under construction for use by the integrated meteorological center (CIMAER) in Brazil. It consists of a set of hybrid models based on determinism and machine learning that use remote sensing data (such as lighting sensor, SODAR, satellite and soon RADAR), in situ data (from the surface weather station and radiosonde) and aircraft data (such as retransmission of aircraft weather data and vertical acceleration). The idea is to gradually operationalize the system to assist CIMAER´s meteorologists in generating their nowcasting, for example, of visibility, ceiling, turbulence, convective weather, ice, etc. with objectivity and precision. Some test results of the developed nowcasting models are highlighted as examples of nowcasting namely: a) visibility and ceiling up to 1h for Santos Dumont airport; b) 6-8h convective weather forecast for the Rio de Janeiro area and the São Paulo-Rio de Janeiro route. Finally, the steps in development and the futures are superficially covered.
Major Surface Melting over the Ross Ice Shelf, Antarctica
Authors: Zou Xun , Bromwich David , Montenegro Alvaro , Wang Sheng-Hung , Bai Lesheng
Published: March 2021

West Antarctica (WA), especially the Ross Ice Shelf (RIS), has experienced more frequent surface melting during austral summer over the past three decades. Surface melting will jeopardize the stability of ice shelves and cause potential ice loss in the future. We investigate four major melt cases over the RIS via Polar WRF simulations driven by ERA5 reanalysis data and MODIS observed albedo. Direct warm air advection, recurring foehn effect, and cloud/upper warm air introduced radiative warming are the three major regional causes of surface melting over WA. Warm marine air can warm the ice surface directly. With significant moisture transport occurring over more than 40% of the time during the melting period, the impact from net radiation can be amplified via the formation of low-level liquid water clouds. Consequently, extensive downward longwave radiation favors the melting expansion over the middle and coastal RIS. Also, for 3 of 4 melt cases, more than 50% of the melting period experiences foehn warming, which can cause a 2 – 4 ºC increase in surface temperature. Isentropic drawdown is usually the dominant foehn mechanism and contributes a 14 ºC temperature increase, especially when strong low-level blocking occurs on the upwind side. Foehn clearance and decreasing surface albedo respectively increase the downward shortwave radiation and decrease the upward shortwave radiation, significantly contributing to surface melting in areas like western Marie Byrd Land. Moreover, frequent foehn cases can enhance the turbulent mixing on the leeside and benefit sensible heat transfer when Froude number is around 1. With better understanding of the regional factors for the surface melting, the prediction of the future stability of West Antarctic Ice Shelves will be improved.
Mapping the groundwater level and soil moisture of a montane peat bog using UAV monitoring and machine learning
Authors: Lendzioch Theodora , Langhammer Jakub , Vlcek Lukas , Minarik Robert
Published: March 2021

One of the best preconditions for sufficient monitoring of peat bog ecosystems requires a unique collection, processing, and analysis of spatial data to understand peat bog dynamics. Over two seasons, we sampled groundwater level (GWL), and soil moisture (SM) ground truth data at two diverse locations at the Rokytka Peat bog within the Sumava Mountains, Czechia. These data served as reference data and were modeled with a suite of potential variables derived from digital surface models (DSMs), RGB-, multispectral-, and thermal orthoimages, reflecting topo-morphometry, vegetation, and surface temperature information, generated from drone mapping. We applied 34 predictors to feed the Random forest (RF) algorithm. Predictors selection, hyperparameter tuning, and performance assessment were accompanied using Leave-Location-Out (LLO) spatial Cross-Validation (CV) joined with the forward feature selection (FFS) to overcome overfitting. The spatial CV performance statistics unveiled low (R2 = 0.12) to high (R2 = 0.78) model predictions. Predictor importance was used for model interpretation, where the temperature has proved the be a powerful impact on GWL and SM and significant other predictors' contributions such as Normalized Difference Index (NDVI), Normalized Difference Index (NDI), Enhanced Red-Green-Blue Vegetation Index (ERGBVE), Shape Index (SHP), Green Leaf Index (GLI), Brightness Index (BI), Coloration Index (CI), Redness Index (RI), Primary Colours Hue Index (HI), Overall Hue Index (HUE), SAGA Wetness Index (TWI), Plan Curvature (PlnCurv), Topographic Position Index (TPI), and Vector Ruggedness Measure (VRM). Additionally, we estimated the area of applicability (AOA) by presenting maps where the prediction model was certainly applied and where the predictions were highly uncertain because machine learning (ML) models make predictions far beyond sampling locations without sampling data and having no knowledge about these environments. The AOA method is perfectly suited and unique for decision-making about the best sampling strategy, notably for limited data to circumvent this issue. 
Quantifying the ocean carbon sink for 1994-2007: Combined evidence from multiple methods
Authors: McKinley Galen A. , Cross Jessica , DeVries Timothy , Hauck Judith , Fay Amanda , Landschützer Peter , Laruelle Goulven G. , Lovenduski Nicole , Monteiro Pedro , Najjar Ray , Resplandy Laure , Rödenbeck Christian , Sabine Christopher , Wanninkhof Rik , Williams Nancy
Published: March 2021

By means of a variety of international observing and modeling efforts, the ocean carbon community has developed numerous estimates for ocean carbon uptake. In this presentation, we report on the synthesis effort we are undertaking under the auspices of an Ocean Carbon and Biogeochemistry Working Group.  Our initial goal for this working group is to determine the best estimate for the net and anthropogenic carbon sink from 1994-2007 based on three approaches that independently use interior data, surface data or hindcast ocean models. Combining two approaches that use interior ocean data to estimate anthropogenic carbon, Fant = -2.40+-0.21 PgC/yr (2 sigma uncertainty). Estimates for the net, or contemporary, ocean carbon uptake come from 6 products that interpolate surface ocean pCO2 data to global coverage: Fnet = -1.58+-0.19  PgC/yr for 1994-2007. Uncertain closure terms for naturally-outgassed river-derived carbon and non-steady state natural carbon fluxes in the open ocean are then added to derive Fant from surface observation-based Fnet. Ocean models do not include river-derived carbon, but do include non-steady state natural carbon fluxes, and thus a third estimate for Fant is derived. The combined best-estimate is Fant = -2.35+-0.53 PgC/yr.  We detail the uncertainties and assumptions made in deriving these estimates, and suggest paths forward to further reduce uncertainties.
Numerical Simulation of Scouring in Overtopping Dam-break Flow
Authors: Huang Can , Wang Xiaoliang , Liu Qingquan
Published: March 2021

Overtopping dam-break flow has great harm to the earthen embankments due to the hydraulic erosion. Some researchers have carried out relevant model experiments, but it is difficult to achieve the experimental conditions for the actual situation. The common numerical simulation is to express the scouring process through the empirical relationship, which obviously could not reflect the real scouring process. In this paper, a new overtopping erosion model using Smoothed Particle Hydrodynamics (SPH) is proposed. When the shear stress on the sediment SPH particle exceeds the critical stress, the erosion process begins. Then, when a sediment SPH particle is completely eroded, it will begin to move and is described as a non-Newtonian fluid. The un-incipient sediment particles are treated as boundary. This model is well validated with plane dike-breach experiment, and has also achieved a good agreement with erodible bed dam-break experiment.