bluuebunny/crossref_metadata_2025 huggingface dataset:
Air-sea exchange of acetone, acetaldehyde, DMS and isoprene at a UK coastal site.
Authors: Phillips Daniel , Hopkins Frances , Bell Thomas , Wohl Charel , Reeves Claire , Nightingale Philip , Liss Peter , Yang Mingxi
Published: March 2021

Volatile organic compounds (VOCs) are ubiquitous in the atmosphere and are important for atmospheric chemistry. Large uncertainties remain in the role of the ocean in the atmospheric VOC budget because of poorly constrained marine sources and sinks. There are very few direct measurements of air-sea VOC fluxes near the coast, where natural marine emissions could influence coastal air quality (i.e. ozone (O3), aerosols) and terrestrial gaseous emissions could be taken up by the coastal seas.

To address this, we present air–sea fluxes of acetone, acetaldehyde and dimethylsulfide (DMS) at the coastal Penlee Point Atmospheric Observatory (PPAO) in the South-West UK during the spring (Apr-May 2018). Fluxes are quantified simultaneously by eddy covariance (EC) using a proton transfer reaction quadrupole mass spectrometer. Comparisons are made between two wind sectors representative of different air-water exchange regimes: the open water sector facing the North Atlantic Ocean and the fetch-limited Plymouth Sound fed by two estuaries.

Mean EC (± 1 standard error) fluxes of acetone, acetaldehyde and DMS from the open-water wind sector were ‑8.01±0.77, ‑1.55±1.44 and 4.67±0.56 μmol m-2 d-1 respectively (- sign indicates air-to-sea deposition). These measurements are generally comparable (same order of magnitude) to previous measurements in the Eastern North Atlantic Ocean at the same latitude. In comparison, the terrestrially influenced Plymouth Sound wind sector showed respective fluxes of -12.93±1.37, -4.45±1.73 and 1.75±0.80 μmol m-2 d-1. The greater deposition fluxes of acetaldehyde and acetone within the Plymouth Sound were largely driven by higher atmospheric concentrations from the terrestrial wind sector. The reduced DMS emission from the Plymouth Sound was caused by a combination of lower wind speed and likely lower dissolved concentrations as a result of the freshwater estuarine influence (i.e. dilution).

In addition, we measured the near surface seawater concentrations of acetone, acetaldehyde, DMS and isoprene from a marine station 6 km offshore. Comparisons are made between EC fluxes from the open water and diffusive VOC fluxes calculated with a two-layer (TL) model of gas transfer using air/water concentrations. The calculated TL fluxes are largely consistent with our direct measurements in the directions and magnitudes of fluxes. Generally, the TL model predicted acetone and acetaldehyde fluxes that were ~12–33 % higher (greater deposition) than the EC measurements. This could be due to sea surface processes that produce these carbonyl compounds that were not accounted for by the TL technique.
Estimating compositions of the deep continental crust
Authors: Sammon Laura , McDonough William , Mooney Walter
Published: March 2021

The deep continental crust's chemical makeup is central to the debate of crustal formation, evolution, strength, and bulk composition. The impenetrable depths and pressures of the deep (roughly > 10 km) crust force geoscientists to rely on indirect sampling methods, studying medium- to high-grade metamorphic terrains and xenoliths to ascertain the composition of the middle and lower continental crust. Analyzing the deep crust in situ requires geophysical data, such as seismic velocities: Vp, Vs, and the Vp/Vs ratio. Each method provides a different perspective on deep crustal composition, but alone, neither is definitive. 

To address the nonuniqueness in crust composition modeling, we use thermodynamic modeling software (i.e. Perple_X) to relate observed seismic velocities to bulk compositions and mineralogies. We present a multidisciplinary model for the composition of Earth's deep crust, using geochemical and geophysical data. Through a Monte Carlo modeling approach, we determine the best-fit geochemical model for bulk middle and lower crustal compositions. For 12 different tectonic regimes, we quantify uncertainties in crustal composition, temperature, and seismic velocity while recognizing our own scientific biases. We present a global model of deep crustal composition conclude that regional scale geological variations benefit from a higher resolution model. Overall, our model forecasts 77% of the deepest continental crust has 45 to 55 wt.% SiO2; 15% 55 to 65 wt.% SiO2; 8% may have > 65 wt.% SiO2. Of perhaps equal or greater importance, however, we present a scalable, modular program that can be altered to incorporate additional petrological and geophysical constraints, allowing geoscientists to more easily compare different scenarios for the deep crust.
4D stress signals in the upper plate record subduction nucleation and lateral propagation
Authors: Shuck Brandon , Gulick Sean , Van Avendonk Harm , Gurnis Michael , Sutherland Rupert , Stock Joann , Hightower Erin , Patel Jiten
Published: March 2021

Subduction zones are fundamental to Earth’s plate tectonic history yet details of how they initiate remain enigmatic. Geodynamic models suggest that early stages of subduction depend on whether underthrusting is driven by horizontal or vertical forces. If horizontal forces dominate, the upper plate experiences compression and uplift followed by extension and subsidence, whereas vertically-forced subduction involves only extension. Geologic evidence from the Izu-Bonin-Mariana forearc supports a ~1 Myr rapid transition, whereas observations from Oman indicate a >8 Myr time lag between initial underthrusting and the onset of upper plate extension. We present seismic images of the incipient Puysegur subduction zone south of New Zealand. Our data show evidence for a stress signal (compression followed by extension) that spread from north to south as the trench initiated and propagated along the plate boundary. Both the magnitude and duration of the compressional phase diminish from ~8 Myrs long in the north to ~5 Myrs in the south. This timing indicates that the transition to self-sustaining subduction is more rapid when an adjacent downgoing slab contributes a driving force that aids subduction initiation. We therefore argue for a new framework in which horizontal forces dominate at sites of subduction nucleation and vertical forces gradually strengthen during later propagation as the developing plate boundary weakens and the slab-pull force intensifies. Our findings corroborate evidence for ancient horizontally-forced subduction initiation events and suggest that the geologic record may be biased, since vertically-forced scenarios of subduction propagation are more likely to be preserved than destructive subduction nucleation events.
Energetic particles and the solar cycle: Impact of solar magnetic field amplitude and geometry on SEPs and GCRs diffusion coefficients
Authors: Perri Barbara , Brun Allan Sacha , Strugarek Antoine , Réville Victor
Published: March 2021

SEPs are correlated with the 11-year solar cycle due to their production by flares and interaction with the inner heliosphere, while GCRs are anti-correlated with it due to the modulation of the heliospheric magnetic field. The solar magnetic field along the cycle varies in amplitude but also in geometry, causing diffusion of the particles along and across the field lines; the solar wind distribution also evolves, and its turbulence affects particle trajectories.

We combine 3D MHD compressible numerical simulations to compute the configuration of the magnetic field and the associated polytropic solar wind up to 1 AU, with analytical prescriptions of the corresponding parallel and perpendicular diffusion coefficients for SEPs and GCRs. First, we analyze separately the impact of the magnetic field amplitude and geometry for a 100 MeV proton. By varying the amplitude, we change the amplitude of the diffusion by the same factor, and the radial gradients by changing the spread of the current sheet. By varying the geometry, we change the latitudinal gradients of diffusion by changing the position of the current sheets. We also vary the energy, and show that the statistical distribution of parallel diffusion is different for SEPs and GCRs. Then, we use realistic solar configurations, showing that diffusion is highly non-axisymmetric due to the configuration of the current sheets, and that the distribution varies a lot with the distance to the Sun, especially at minimum of activity. With this model, we are thus able to study the direct influence of the Sun on Earth spatial environment in terms of energetic particles. 
Modelling the ocean circulation and the basal melting in the Prydz Bay-Amery Ice Shelf system
Authors: Jin Jing , Payne Antony J. , Seviour William , Bull Christopher
Published: March 2021

The basal melting of the Amery Ice Shelf (AIS) in East Antarctica and its connections with the oceanic circulation are investigated by a regional ocean model. The simulated estimations of net melt rate over AIS from 1976 to 2005 vary from 1 to 2 m/yr depending primarily due to inflow of modified Circumpolar Deep Water (mCDW). Prydz Bay Eastern Costal Current (PBECC) and the eastern branch of Prydz Bay Gyre (PBG) are identified as two main mCDW intrusion pathways. The oceanic heat transport from both PBECC and PBG has significant seasonal variability, which is associated with the Antarctic Slope Current. The onshore heat transport has a long-lasting effect on basal melting. The basal melting is primarily driven by the inflowing water masses though a positive feedback mechanism. The intruding warm water masses destabilize the thermodynamic structure in the sub-ice shelf cavity therefore enhancing the overturning circulations, leading to further melting due to increasing heat transport. However, the inflowing saltier water masses due to sea-ice formation could offset the effect of temperature through stratifying the thermodynamic structure, then suppressing the overturning circulation and reducing the basal melting.
Localizing the Source of Type II Emission Around a CME with the Sun Radio Interferometer Space Experiment (SunRISE) and MHD Simulations
Authors: Hegedus Alexander , Manchester Ward , Kasper Justin , Lazio Joseph , Romero-Wolf Andrew
Published: March 2021

The Earth’s Ionosphere limits radio measurements on its surface, blocking out any radiation below 10 MHz. Valuable insight into many astrophysical processes could be gained by having a radio interferometer in space to image the low frequency window, which has never been achieved. One application for such a system is observing type II bursts that track solar energetic particle acceleration occurring at Coronal Mass Ejection (CME)-driven shocks. This is one of the primary science targets for SunRISE, a 6 CubeSat interferometer to circle the Earth in a GEO graveyard orbit. SunRISE is a NASA Heliophysics Mission of Opportunity that began Phase B (Formulation) in June 2020, and plans to launch for a 12-month mission in mid-2023. In this work we present an update to the data processing and science analysis pipeline for SunRISE and evaluate its performance in localizing type II bursts around a simulated CME.

To create realistic virtual type II input data, we employ a 2-temperature MHD simulation of the May 13th 2005 CME event, and superimpose realistic radio emission models on the CME-driven shock front, and propagate the signal through the simulated array. Data cuts based on different plasma parameter thresholds (e.g. de Hoffman-Teller velocity and angle between shock normal and the upstream magnetic field) are tested to get the best match to the true recorded emission.  This model type II emission is then fed to the SunRISE data processing pipeline to ensure that the array can localize the emission. We include realistic thermal noise dominated by the galactic background at these low frequencies, as well as new sources of phase noise from positional uncertainty of each spacecraft. We test simulated trajectories of SunRISE and image what the array recovers, comparing it to the virtual input, finding that SunRISE can resolve the source of type II emission to within its prescribed goal of 1/3 the CME width. This shows that SunRISE will significantly advance the scientific community’s understanding of type II burst generation, and consequently, acceleration of solar energetic particles at CMEs.  This unique combination of SunRISE observations and MHD recreations of space weather events will allow an unprecedented look into the plasma parameters important for these processes. 
Multi-source flood mapping for rapid impact assessment
Authors: Schröter Kai , Steinhausen Max , Brill Fabio , Lüdtke Stefan , Eggert Daniel , Merz Bruno , Kreibich Heidi
Published: March 2021

Globally increasing flood losses due to anthropogenic climate change and growing exposure underline the need for effective emergency response and recovery. Knowing the inundation situation and resulting losses during or shortly after a flood is crucial for decision making in emergency response and recovery. With increasing amounts of data available from a growing number and diversity of sensors and data sources, data science methods offer great opportunities for combining data and extracting knowledge about flood processes in near real-time.

The main objective of this research is to develop a rapid and reliable flood depth mapping procedure by integrating information from multiple sensors and data sources. The created flood depth maps serve as input for the prediction of flood impacts. This contribution presents outcomes of a demonstration case using the flood of June 2013 in Dresden (Germany) where satellite remote sensing data, water level observations at the gauge Dresden and Volunteered Geographic Information based on social media images providing information about flooding are combined using statistical and machine learning-based data fusion algorithms. A detailed post-event inundation depth map based on terrestrial survey data and aerial images is available as a reference map and is used for evaluation. First results show that the individual datasets have different strengths and weaknesses. The combination of multiple data sources is able to counteract the weaknesses of single datasets and provide a significantly improved flood map and impact assessment. Our work is conducted within the Digital Earth Project (.

 
Projections of future atmospheric circulation changes using the extratropical linear step response to tropical precipitation
Authors: Senior Natasha , Matthews Adrian , Joshi Manoj
Published: March 2021

The global hydrological cycle is expected to intensify under a warming climate. Since extratropical Rossby wave trains are triggered by tropical convection, this will impact the atmospheric circulation in the extratropics. Owing to the approximate linearity of the teleconnection pattern, we can use a method based in linear response theory to quantify this extratropical response using a step response function. We have examined the step response functions for a selection of CMIP5 pre-industrial control runs and reanalysis data,  in particular studying the response during the boreal winter. We found there to a large intermodel spread in the response pattern owing to differences in representations of the model basic state. In the current work, we use a 'perfect model' approach to conduct a systematic study of the performance of the linear response method in projecting future winter-time northern hemisphere circulation changes using the present day (1986-2005) model basic states, comparing these to those projected by CMIP5 models under a 3 degree rise in mean global temperature anomaly above pre-industrial. We demonstrate how, given a projected precipitation change pattern, the linear response theory method can compete with the models in providing faithful projections for the extratropical circulation changes.
Modeling the influence of biogeochemical and ecosystem processes on microplastic transport in the Arctic seas on the example of Oslofjord
Authors: Berezina Anfisa , Yakushev Evgeniy , Ivanov Boris
Published: March 2021

Currently, all natural environments, including the Arctic seas, are contaminated by microplastics (MP, plastic fragments less than 5 mm). Biogeochemical processes significantly affect the physical properties of MP, primarily its density due to biofouling.
The aim of this work is to develop a numerical model for assessing the fate of MP in the marine environment under the influence of natural biogeochemical cycles in the Arctic seas on the example of Oslofjord.
The biogeochemical model OxyDep (E. V. Yakushev et al., 2011) was used to reproduce the temporal variability of the phyto- and zooplankton, dissolved and particulate organic matter. The two-dimensional 2D benthic-pelagic transport model (2DBP), which considers the processes in the water column and bottom sediments together, is used as a hydrophysical model.
The separate module which describes the transformation of the MP under biogeochemical processes was developed. The biogeochemical and MP modules were coupled with the transport model using the Framework for Aquatic Biogeochemical Modeling (FABM) (Bruggeman & Bolding, 2014).
The results show, that there would be a decrease in the MP content in the surface layer in summer period due to the ingestion by zooplankton and its transfer to the sediments. Based on the obtained patterns, it is possible to predict zones of accumulation of MP for a specific water area, depending on the local ecosystem.

Funding: The reported study was funded by RFBR, project number 20-35-90056. This work was partly funded by the Norwegian Ministry of Climate and Environment project RUS-19/0001 “Establish regional capacity to measure and model the distribution and input of microplastics to the Barents Sea from rivers and currents (ESCIMO)” and the Russian Foundation for Basic Research, research project 19-55-80004.
Precursory and post-failure analysis of landslide deformation in Danba County, China using optical remote sensing and Multi-temporal InSAR (MTI) methods with corner reflectors
Authors: Xia Zhuge , Motagh Mahdi , Li Tao
Published: March 2021

On 17 June 2020, a large debris flow triggered by continuous heavy precipitation hit the Danba County in southwest China, blocked the river and a barrier lake was formed. Meanwhile, on the other side of the river, a large-scale landslide was triggered due to the reactivation of the ancient landslide body. Then an evacuation of more than 20000 people leaving their home town was urgently conducted.
This study exploits multi-sensor remote sensing techniques to assess landslide deformation, precursory deformation and post-failure motion of Danba landslide. We start with optical remote sensing images using the cross correlation method to investigate the overall information about this collapse, such as magnitude and moving direction of the sliding. Two high-resolution remote sensing optical images from Planet are processed right before and after the failure.
Moreover, we apply the advanced Multi-temporal InSAR (MTI) techniques such as Persistent Scatterer Interferometry (PSI) and Small Baseline Subsets (SBAS) to analyze the precursors of the landslide over the long term. Based on the results of optical remote sensing, the descending Sentinel-1 data in 2014-2020 are extensively exploited with a better geometry of satellite observation. The long-term and transient of the deformation are analyzed against variations of precipitation, and then the related early warning systems are further explored.
The last stage of the work is the monitoring of current movements in the collapse region after the failure. It is explored by using multiple SAR datasets including C-band Sentinel-1 and X-band TerraSAR-X (TSX) high-resolution SAR images. With the help of the field works by our collaborators, stable artificial corner reflectors (CR) are deployed on selected sites to evaluate their performance in deriving landslide kinematics. Different from the traditional Triangle CR (TCR), the new design of dihedral CR (DCR) are introduced and exploited on the scene. The performance of this new design towards MTI processing and sub-pixel offset-tracking processing is examed and tested in this study. Results are presented and further discussed for a better assessment of Danba landslide.
The results of this paper can provide new strategies for developing an early warning system in this landslide using remote sensing technologies. Besides, the post-failure results are compared with the pre-event analysis, which could give an associated and comprehensive understanding of the whole landslide kinematics.
Spatial variation of periods of ion and neutral waves in a solar magnetic arcade.
Authors: Kuźma Błażej , Murawski Kris , Musielak Zdzisław , Poedts Stefaan , Wójcik Dariusz
Published: March 2021

We present a new insight into the propagation of ion magnetoacoustic and neutral acoustic waves in a magnetic arcade in the lower solar atmosphere. By means of numerical simulations, we aim to: (a) study two-fluid waves propagating in a magnetic arcade embedded in the partially-ionized, lower solar atmosphere; and (b) investigate the impact of the background magneticfield configuration on the observed wave-periods. We consider a 2D approximation of the gravitationally stratified and partially-ionized lower solar atmosphere consisting of ion + electron and neutral fluids that are coupled by ion-neutral collisions. In this model, the convection below the photosphere is responsible for the excitation of ion magnetoacoustic-gravity and neutral acoustic-gravity waves. We find that in the solar photosphere, where ions and neutrals are strongly coupled by collisions, magnetoacoustic-gravity and acoustic-gravity waves have periods ranging from250s to350s. In the chromosphere, where the collisional coupling is weak, the wave characteristics strongly depend on the magnetic field configuration. Above the foot-points of the considered arcade, the plasma is dominated by vertical magnetic field along which ion slow magnetoacoustic-gravity waves are guided. These waves exhibit a broad range of periods with the most prominent periods of 180 s, 220 s, and 300 s. Above the main loop of the solar arcade, where mostly horizontal magnetic field lines guide ion magnetoacoustic waves, the main spectral power reduces to the period of about 180 s and longer wave-periods do not exist. The obtained results demonstrate unprecedented, never reported before level of agreement with the recently reported observational data of Wisniewska et al. (2016) and Kayshap et al. (2018). We demonstrate that the two-fluid approach is indeed crucial for a description of wave-related processes in the lower solar atmosphere, with energy transport and dissipation being of the highest interest among them.
Hybrid Architectures with Quantum Gravity Gradiometry and Satellite-to-Satellite Tracking for Spaceborne Mass Change Measurements - A Sensitivity and Performance Analysis
Authors: Rosen Mitchell , Bettadpur Srinivas , Chiow Sheng-wey , Yu Nan
Published: March 2021

Advances in atom interferometry have led to quantum gravity gradiometer instruments, which have further led to spaceborne mission concepts utilizing this technology to measure Earth’s gravity field and its time variations. The mass changes inferred from gravity change measurements lead to greater understanding of the dynamical Earth system, as demonstrated by GRACE and GRACE Follow-On missions.

We report the results from a sensitivity and performance assessment study with quantum gradiometers used in two configurations – first as a single-axis gradiometer with a GNSS receiver; and second in a novel hybrid configuration combining cross-track quantum gravity gradiometer and an inter-satellite tracking system. The relative advantages of the two configurations are assessed in terms of their susceptibility to system errors (such as tracking, pointing, or measurement errors), and to modeling errors due to aliasing from rapid time- variations of gravity (so-called “de-aliasing errors”). We evaluate and discuss the impact of de-aliasing errors on gravity fields resulting from the study. We conclude with a specification of the key measurement error thresholds for a notional hybrid gravity field mapping mission.

Part of the research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004).

Acknowledgement: UTCSR effort was funded by JPL grant 1656926. Use of resources at the Texas Advanced Computing Center is gratefully acknowledged. 
If you work with phenology, you work with bud cold hardiness dynamics
Authors: Kovaleski Al , Londo Jason
Published: March 2021

Budbreak is one of the most observed and studied phenological phases in perennial plants. Historically, two effects of temperature are used to model budbreak: the accumulation of heat units (forcing); and the accumulation of time spent at low temperatures (chilling). These two effects have a well-established negative correlation: the more chilling, the less forcing is required to reach budbreak. However, prediction of budbreak remains a challenge, as even artificial warming experiments do not match changes in observed budbreak timing during the past few decades of climate warming. The cold hardiness of buds is, however, largely ignored in estimations of timing to budbreak. Cold hardiness level fluctuates throughout the winter as temperatures change, constantly altering the initiation point of deacclimation. During budbreak assays, cold hardiness loss is extremely slow (low deacclimation rate) at low chill accumulation, and increases to a maximum at high chill accumulation. By standardizing deacclimation rates for each species based on the maximum observed, a deacclimation potential describes dormancy fulfillment. Our studies show that deacclimation rates vary at different temperatures demonstrating the effect of forcing is non-linear. We show that the concept of variable chilling requirements for satisfying dormancy (high chill vs. low chill) is largely erroneous and instead these phenotypes reflect previously unmeasured differences between species or genotypes regarding the interaction between cold hardiness state and deacclimation potential. Our studies show that forcing responses (maximum rates of deacclimation) are normally distributed within a species, and are a heritable trait. Three effects of temperature are thus necessary to describe contemporary phenology patterns as well as predict future impacts of climate change: the accumulation of chill, the forcing temperature response, and the cold hardiness of buds.
Intraplate volcanism triggered by bursts in slab flux
Authors: Mather Ben , Muller Dietmar , Seton Maria , Ruttor Saskia , Nebel Oliver , Mortimer Nick
Published: March 2021

Long-lived, widespread intraplate volcanism without age progression is one of the most controversial features of plate tectonics. The eastern margin of Australia and Zealandia has experienced extensive mafic volcanism over the last 100 million years. A plume origin has been proposed for three distinct chains of volcanoes, however, the majority of eruptions exhibit no clear age progression. Previously proposed edge-driven convection, asthenospheric shear, and lithospheric detachment fail to explain the non age-progressive eruptions across the ~5000 km wide intraplate volcanic province from Eastern Australia to Zealandia. We model the subducted slab volume over 100 million years and find that slab flux drives volcanic eruption frequency, indicating stimulation of an enriched mantle transition zone reservoir. Volcanic isotope geochemistry allows us to distinguish a HIMU reservoir (>1 Ga old) in the slab-poor south, from a northern EM1/EM2 reservoir, reflecting a more recent voluminous influx of oceanic lithosphere into the mantle transition zone. We provide a unified theory linking plate boundary and slab volume reconstructions to upper mantle reservoirs and intraplate volcano geochemistry.
Paleohydraulic investigation of the Ebro Basin: Implications for Mars
Authors: Geil-Haggerty Heath
Published: March 2021

The stratigraphy preserved in Earth’s sedimentary basins offers a record of how landscapes have evolved with time.  This stratigraphy provides insights into the dynamic processes that shaped the surface of the earth.  Fluvial stratigraphy contains many elements that can be used to recreate past conditions in ancient river channels.  Paleohydraulic reconstruction uses measurements of fluvial stratigraphy to model the conditions in the system that created them.  This allows us to answer questions related to water discharge, sediment flux, and duration of fluvial activity.  These are key questions when investigated in the context of Mars.  Paleohydraulic models can be used as compelling analogs for similar systems on Earth as well as Mars and other rocky planets.           

This study examines what the record of Oligocene-Miocene fluvial stratigraphy in northeastern Spain’s Ebro Basin can tell us about water discharge and sediment flux across distributive fluvial systems at a basin scale.  The Cenozoic stratigraphy of northeastern Spain’s triangular shaped Ebro Basin embodies a classic example of the formation of a closed sedimentary basin.  The Ebro Basin contains a number of remarkably well exposed fluvial sedimentary deposits.  These deposits outcrop as distinctive laterally contiguous channel sand bodies.  Clastic sediment supply in the Ebro Basin is largely governed by tectonic uplift and basin subsidence related to the Pyrenean orogen with peripheral contributions from the Catalan Coast and Iberian Ranges.  We test the idea that the record of conditions in the fluvial systems should reflect the record of lacustrine chemical sediments through sediment mass conservation.  In order to test this hypothesis measurements of bedform height, barform height, sediment size, and paleochannel dimensions were collected in the field.  Our paleohydraulic model uses previously derived theoretical and empirical relationships to recreate the conditions in these ancient fluvial systems.  These results are scaled up by accounting for drainage density and intermittency in order to address the principal question at a basin scale.  Paleodischarges from the fluvial sediments are comparable to those from river chemistry calculations for the lacustrine facies. 
Rainfall Characteristics from Convection-Permitting Downscaling over the Western Maritime Continent
Authors: Prasanna Venkatraman , Sahany Sandeep , Moise Aurel F. , Chua Xin Rong , Lim Gerald , Hassim Muhammad E. , Chen Chen
Published: March 2021

Long-term convection-permitting dynamical downscaling has been carried out over the western Maritime Continent, using the Singapore Variable Resolution Regional Climate Model (SINGV-RCM) at 8km and 2km spatial resolutions. The SINGV-RCM is forced with ERA-5 reanalyses data for a 36-year period (1979-2014) at 8km resolution over Southeast Asia (79E-160E;16S-24N) with regular update of the sea surface temperature at 6-hr interval; further, this 8km domain simulation is used for forcing a smaller domain over the western Maritime continent at a resolution of 2km (93E-110E;7.2S-9.9N) for a 20-year period (1995-2014). Rainfall characteristics including the diurnal cycle and extremes from the two simulations evaluated against satellite retrievals, and the added value from dynamical downscaling will be presented.
Big Data Assimilation: Real-time Demonstration Experiment of 30-second-update Forecasting in Tokyo in August 2020
Authors: Miyoshi Takemasa , Honda Takumi , Amemiya Arata , Otsuka Shigenori , Maejima Yasumitsu , Taylor James , Tomita Hirofumi , Nishizawa Seiya , Sueki Kenta , Yamaura Tsuyoshi , Ishikawa Yutaka , Satoh Shinsuke , Ushio Tomoo , Koike Kana , Hoshi Erika , Nakajima Kengo
Published: March 2021

The Japan’s Big Data Assimilation (BDA) project started in October 2013 and ended its 5.5-year period in March 2019. Here, we developed a novel numerical weather prediction (NWP) system at 100-m resolution updated every 30 seconds for precise prediction of individual convective clouds. This system was designed to fully take advantage of the phased array weather radar (PAWR) which observes reflectivity and Doppler velocity at 30-second frequency for 100 elevation angles at 100-m range resolution. By the end of the 5.5-year project period, we achieved less than 30-second computational time using the Japan’s flagship K computer, whose 10-petaflops performance was ranked #1 in the TOP500 list in 2011, for past cases with all input data such as boundary conditions and observation data being ready to use. The direct follow-on project started in April 2019 under the Japan Science and Technology Agency (JST) AIP (Advanced Intelligence Project) Acceleration Research. We continued the development to achieve real-time operations of this novel 30-second-update NWP system for demonstration at the time of the Tokyo 2020 Olympic and Paralympic games. The games were postponed, but the project achieved real-time demonstration of the 30-second-update NWP system at 500-m resolution using a powerful supercomputer called Oakforest-PACS operated jointly by the Tsukuba University and the University of Tokyo. The additional developments include parameter tuning for more accurate prediction and complete workflow to prepare all input data in real time, i.e., fast data transfer from the novel dual-polarization PAWR called MP-PAWR in Saitama University, and real-time nested-domain forecasts at 18-km, 6-km, and 1.5-km to provide lateral boundary conditions for the innermost 500-m-mesh domain. A real-time test was performed during July 31 and August 7, 2020 and resulted in the actual lead time of more than 27 minutes for 30-minute prediction with very few exceptions of extended delay. Past case experiments showed that this system could capture rapid intensification and decays of convective rains that occurred in the order of less than 10 minutes, while the JMA nowcasting did not predict the rapid changes by its design. This presentation will summarize the real-time demonstration during August 25 and September 7 when Tokyo 2020 Paralympic games were supposed to take place.
Modelling extreme wave conditions for survivability tests of wave energy converters: CFD versus model tests
Authors: Gubesch Eric , Abdussamie Nagi , Penesis Irene , Chin Christopher , Wang Chien Ming
Published: March 2021

This study investigates the experimental and numerical generation of realistic extreme waves in the Model Test Basin (MTB) at the Australian Maritime College, University of Tasmania, in order to test the survivability of offshore structures such as wave energy converters. The sea state and maximum wave height considered were collected during Tropical Cyclone Oma as it tracked down the Queensland Coast of Australia in February 2019. Upon successful generation of a repeatable experimental sample, the NewWave theory was used to regenerate the MTB surface elevation in a STAR-CCM+ computational fluid dynamics (CFD) numerical wave tank. The experimental surface elevation data was analysed with a fast Fourier transform to obtain the wave component amplitudes (an) and phase angles (εn).  These parameters were then used to generate a polychromatic wave in CFD. The 2D CFD simulations were extended to a 3D simulation that included an oscillating water column wave energy converter as per the experimental conditions. Results indicate that experimental focused wave groups can be replicated in CFD software with a similarity of 0.9407 for 2D simulations.  However, by applying an amplification factor to the crest amplitude of the focussed waves, one may further obtain improved accuracy in both 2D and 3D simulations. Further mesh resolution studies surrounding the oscillating water column may improve the accuracy of 3D fluid structure interaction simulations when investigating survivability.
Impact of extreme hydrological perturbation on sediment distribution from source to sink, PETM, Spain.
Authors: Prieur Marine , Whittaker Alexander C. , Schlunegger Fritz , Sømme Tor O. , Braun Jean , Castelltort Sebastien
Published: March 2021

Sedimentary dynamics and fluxes are influenced by both autogenic and allogenic forcings. A better understanding of the evolution of sedimentary systems through time and space requires us to decipher, and therefore to characterise, the impact of each of these on the Earth’s landscape. Given the current increase in the concentration of atmospheric carbon, studying the impact of rapid and global climate changes is of particular importance at the present time. Such events have been clearly defined in the geologic record. Among them, the Paleocene-Eocene Thermal Maximum (PETM) has been extensively studied worldwide and represents a possible analogue of the rapid current climate warming.

The present project focuses on the Southern Pyrenees (Spain) where excellent exposures of the Paleocene-Eocene interval span a large range of depositional environments from continental to deep-marine. These conditions allow us to collect data along the whole depositional system in order to document changes in sediment fluxes and paleohydraulic conditions. Because hydrological conditions have an impact on sediment transport through hydrodynamics, paleoflow reconstructions can shed light on changes in sediment dynamics. This information is reconstructed from the statistical distributions of channel morphologies, characteristic system dimensions including bankfull channel depth and width, and grain-sizes.

With this approach, our aim is to provide both qualitative and quantitative assessments of the magnitude and extent of the perturbation of sedimentary fluxes along an entire source-to-sink system during an episode of extreme climate change. This will lead to a better understanding of the impact of abrupt climate change on earth surface systems in mid-latitudinal areas, with possible implications for current climate adaptation policy.

This research is carried out in the scope of the lead author’s PhD project and is part of the S2S-FUTURE European Marie Skłodowska-Curie ITN (Grant Agreement No 860383).
Catchment to model space mapping – learning transfer functions from data by symbolic regression
Authors: Feigl Moritz , Schweppe Robert , Thober Stephan , Herrnegger Mathew , Samaniego Luis , Schulz Karsten
Published: March 2021

The Function Space Optimization (FSO) method, recently developed by Feigl et al. (2020), automatically estimates the transfer function structure and coefficients to parameterize spatially distributed hydrological models. FSO is a symbolic regression method, searching for an optimal transfer function in a continuous optimization space, using a text generating neural network (variational autoencoder).

We apply our method to the distributed hydrological model mHM (www.ufz.de/mhm), which is based on a priori defined transfer functions. We estimate mHM transfer functions for the parameters “saturated hydraulic conductivity” and “field capacity”, which both influence a range of hydrologic processes, e.g. infiltration and evapotranspiration.

The FSO and standard mHM approach are compared using data from 229 basins, including 7 large training basins and 222 smaller validation basins, distributed across Germany. For training, 5 years of data of 7 gauging stations is used, while up to 35 years, with a median of 32 years, are used for validation. This setup is adopted from a previous study by Zink et al. (2017), testing mHM in the same basins and which is used as a benchmark. Maps of soil properties (sand/clay percentage, bulk density) and topographic properties (aspect, slope, elevation) are used as possible inputs for transfer functions.

FSO estimated transfer functions improved the mHM model performance in the validation catchments significantly when compared to the benchmark results, and only show a small decrease in performance compared to the training results. Results demonstrate that an automatic estimation of parameter transfer functions by FSO is beneficial for the parameterization of distributed hydrological models and allows for a robust parameter transfer to other locations.

 

Feigl, M., Herrnegger, M., Klotz, D., & Schulz, K. (2020). Function Space Optimization: A symbolic regression method for estimating parameter transfer functions for hydrological models. Water resources research, 56(10), e2020WR027385.

Zink, M., Kumar, R., Cuntz, M., & Samaniego, L. (2017). A high-resolution dataset of water fluxes and states for Germany accounting for parametric uncertainty. Hydrol. Earth Syst. Sci, 21, 1769-1790.
Brown Carbon Sources in Singapore Identified by Factor Analysis of Atmospheric Pressure Chemical Ionization Mass Spectra
Authors: Yang LiuDongQing , Wang Xianfeng , Kuwata Mikinori Kuwata
Published: March 2021

Brown carbon (BrC) is an important candidate for the direct radiative effects of aerosol particles. It has been demonstrated that positive matrix factorization (PMF) is useful in analyzing Aerosol Mass Spectrometer (AMS) data for BrC source apportionment. However, fragmentation of molecular ions in AMS has been limiting its capability to categorize BrC sources. Soft-ionization mass spectrometric techniques are known to retain molecular information of chemical species. In this study, we applied atmospheric pressure chemical ionization mass spectrometry (APCI-MS) to identify the sources of water-soluble BrC. PM2.5 filter samples were collected at a site in Singapore during March-May of 2019. The extracted water-soluble organic matter (WSOM) was analyzed using APCI-MS, time-of-flight aerosol chemical speciation monitor (ToF-ACSM) and ultraviolet-visible spectrophotometer (UV-Vis). Five factor components were obtained by PMF analysis of the APCI-MS data. The PMF output and UV-Vis data were subsequently used to estimate the absorption Ångstrom exponents (AAE) of WSOM in each component. The estimated values of AAE ranged from 3.95 to 8.71. When comparing the factor contributions with simultaneously monitored gas and aerosol data, we found that the factor with the lowest value of AAE was likely emitted from a methane-rich combustion source, located east of the observation site. 
Geothermal Geotechnics development program as a commonly used solution in D-wall.
Authors: Kacprzak Grzegorz , Stasiukiewicz Tomasz , Bagiński Rafał , Frydrych Mateusz , Piotrowski Marcin
Published: March 2021

The project relates to an idea consisting in the use of diaphragm walls constituting a substructure system most often used during the foundation of a large volume building structure in tight urban fabric. Additionally, it offers the possibility of using this substructure as near-surface geothermal geotechnics and in conjunction with adjacent soil as an interseason heat storage in the form of enclosed box. The effect of the following development program is expected to provide a product in the form of concrete elements, that are already required for structural reasons, as diaphragm walls and barrettes with an integrated geothermal installation that allows obtaining part of the heat energy necessary for the operation of a renewable energy building. The accumulated energy, in the form of a lower energy source will be used to heat the building in winter. In summer,  the reduced temperature of diaphragm walls in relation to weather conditions will allow the building to cool down, and thus will power air conditioning systems. This will feature not only concerns about environment aspects but also provides a long-term cost-saving solution that will limit building maintenance.

Presented, currently running, two years program is an effect of cooperation between experienced deep foundation contractor and The Institute of Heat Engineering, scientific unit. The development program, presented below, is based on the industrial research phase in which the lower heat source systems are modelled in Ansys Fluent and then the calculation results are reproduced under laboratory conditions on small physical 3x2x0.7m models. The results from measurements with temperature sensors and IR cameras are used to calibrate the FEM models and to determine the most optimal distribution of the pipes with the fluid carrier.  Stage 2 will allow the analysis of the impact of thermal stress generated by the geothermal installation on the construction of the diaphragm walls and the entire building using deformation sensors.  Development works in stage 3 will allow verification of the above assumptions using real commercial construction in the interseasonal cycle.

The most significant effect of the development programme, stage 4,  will be the creation of a simple tool, on the basis of empirical data collected during model works and prototype tests, to commonly determine the thermal balance for building structures under given ground conditions for commercial buildings. The aim of the tool, being acquired by a deep foundation contractor, is a popularization of the thermo-active ground structures solutions and promotion of geothermal energy utilization.
Measuring soil erosion resistance on coastal dikes linking hyperspectral UAV-data, plant traits and soil information
Authors: Schönebeck Jan-Michael , Paul Maike , Lojek Oliver , Schröder Boris , Visscher Jan , Schlurmann Torsten
Published: March 2021

The integrity of a sea dike, especially its surface soil and biological revetment, is indispensable for coastal protection, as a dike breach would result in damages and economic losses. Estimates of the condition of a sea dike are typically established by on-site inspections and expert judgement at regular intervals. These status assessments of the protection level of the sea dike evaluate grass coverage and animal burrows, since structural inconsistencies deter the overall safety levels on coastal protection. In laboratory settings, erosion resistance of a sea dike is often determined by means of assessing critical shear stress induced by wave-run up and overtopping. Whereby the grain size distribution and soil aggregate formation on the one hand and the root penetration of the sample on the other are significant factors influencing critical shear stress and therefore erosion resistance. 
Drone-/UAV-based remote sensing can be used to easily determine the degree of coverage of the dike revetment via green value detection. Thermal spectroscopy is also already used in agriculture to detect the state of health of plants at an early stage, for example due to a shortage of water. In addition, plants can be classified using hyperspectral imaging data. 
We aim to derive transfer functions correlating ground truthing data, drawn from coastal real world- and a full scale laboratory dike, with plant species, its characteristic taxonomic traits and assessed top soil parameters. This approach bears the advantage of yielding an erosion-resistance estimate of the dike cover based on the plant classification using UAV-derived hyperspectral information. Furthermore, taxonomic species are sought to be paired with their respective, site specific, root architecture. Soil parameters such as nutrient availability and humidity will be observed and integrated into the approach, as they bear an impact on subterranean vegetation growth in that plants with lower nutrient availability develop a higher root network (high root length density [cm/cm³]). Finally, grazing livestock on the dike impacts the root system and soil structure as well and both aspects will be investigated comparing mowed against grazed areas as preliminary results show a dike cover void of grazing livestock exhibits a higher root shoot ratio than one with grazing. We hypothesize that classifying plants based on optical, hyperspectral UAV-derived data and the knowledge about the composition of the subsoil, the correlation of plant-specific root architecture and root growth with nutrient availability and agricultural maintenance could provide valuable information about erosion resistance of the dike cover to support dike inspection on an objective basis.