bluuebunny/crossref_metadata_2025 huggingface dataset:
Critical dynamics governing the lateral flow of magmatic slurries
Authors: Petford Nick , Koenders Curt
Published: March 2022

Magmas are particle-fluid mixtures and as such governed by the physical laws that determine flow and deformation in granular slurries. However, developing quantitative models that combine conduit-scale flow properties with the local generation of flow instabilities that lead to pattern formation, for example layering, segregation or clumping/jamming of crystals during transit, remains a challenge.

Here we provide a detailed theoretical analysis of the lateral flow of a granular magmatic slurry, with application to flow differentiation and layering in mafic sill complexes. The slurry rheology is decomposed into scalar and vector components of the fluctuations in the time-dependent configuration of the particles, which although operating on different scales, together give rise to fluctuations in velocity and particle concentrations that may impart considerable heterogeneity during flow.

A key determinant in the development of geological features of interest is the ratio of flow velocity to the gravitational settling rates of crystals in suspension.  Equations are derived that explore the relative contribution of lateral, pressure gradient or volume-driven lateral conduit flow (G) to rates of crystal settling (H). The key ratio G/H ~ D is defined for both symmetrical and non-symmetrical flow as a function of particle pressure, the latter key in controlling crystal-liquid segregation. Two regimes are identified, D < 1 (crystal settling/sedimentation dominates) and D > 1 where differentiation and layering are emergent properties intrinsic to the flow.  Sensitivity analysis reveals the upper and lower boundary conditions at the magma-country rock interface play a critical (and unique) role in controlling velocity fluctuations that impact on local flow segregation and layering.

Lack of experimental evidence, or real-time observations of magmatic intrusions, means critical open questions remain concerning the precise thermo-mechanical conditions (density contrasts, crystallinity and pressure gradients), needed to match theory with the natural world. However, theoretical treatment sets the scene for follow-up numerical work and experimental verification while providing new insight into factors contributing to chemical diversity and textural heterogeneity in igneous rocks.
Parameterisation of radon diffusivity and exhalation rate from soils – limitations and its applicability to other trace gases
Authors: Karstens Ute , Levin Ingeborg
Published: March 2022

Quantitative understanding of the processes governing radon production and transport in soils and its exhalation rate into the atmospheric boundary layer are essential if we want to use this radioactive noble gas to assess above- and below-ground transport processes. While production of radon in soils is mainly governed by static soil properties such as texture and uranium content, the dominant parameter modulating its exhalation rate is volumetric soil moisture. Here we present an improved process-based high-resolution radon flux map for Europe, using up-to-date soil property maps, including updated uranium activity concentration data from the European Atlas of Natural Radiation. Daily radon exhalation is calculated based on high-resolution soil moisture estimates from the ERA5 and the GLDAS Noah land surface models.  Depending on the soil moisture model used, estimated radon fluxes show differences as large as a factor of two, but modelled soil moisture and corresponding modelled radon fluxes also differ from observations. This highlights the importance of accurate representative soil moisture observations for model validation. Although the fluxes of biogeochemical reactive trace gases at the soil-atmosphere interface are also driven by other variable parameters, such as temperature or microbial activity, their net fluxes can often also be limited by effective diffusivity in the upper soil layers, and thus by soil moisture. Estimating variability and uncertainty of biogeochemical active trace gas fluxes such as methane or hydrogen on the regional or continental scale could therefore benefit from experience with the noble gas radon.
European grapevine moth and Vitis vinifera L. phenology in the Douro region: (a)synchrony and climate scenarios
Authors: Reis Samuel , Martins Joana , Gonçalves Fátima , Carlos Cristina , Santos João A.
Published: March 2022

The European grapevine moth, Lobesia botrana (Lepidoptera: Tortricidae) is considered to be the main pest in the vineyards of the Douro Demarcated Region due to the economic losses it can cause. The phenology of both the grapevine and the pest has changed in the last decades due to the increase in temperature. Therefore, we assess the potential impact of climate change on the (a)synchrony of both species. The results show that the phenological stages (budburst, flowering and veraison) undergo an advancement throughout the region (at an ~1 km resolution) under a climate change scenario (Representative Concentration Pathways, RCP8.5) for the period 2051–2080, with respect to the historic period (1989–2015). For cv. Touriga Nacional and Touriga Franca, the budburst advances up to 14 days, whereas for flowering and veraison the advancements are up to 10 days (mainly at low elevations along the Douro River). For the phenology of Lobesia botrana, earliness was also verified in the three flights (consequently there may be more generations per year), covering the entire region. Furthermore, the third flight advances further compared to the others. For both varieties, the interaction between the third flight (beginning and peak) and the veraison date is the most relevant modification under the future climate change scenario (RCP8.5, 2051–2080). The aforementioned outcomes from the phenology models help to better understand the possible shifts of both trophic levels in the region under future climate, giving insights into their future interactions. To summarize, this study provides new knowledge at a regional scale and with a medium-long term projection (2051–2080). The projection mainly takes into account the RCP8.5 climate scenario.

Keywords: Lobesia botrana; grapevine; varieties; synchrony; climate scenario; Douro Demarcated Region; phenology models; simulations; spatial-temporal map.
Improving SAR Altimeter processing over the coastal zone - the ESA HYDROCOASTAL project
Authors: Cotton David ,   HYDROCOASTAL
Published: March 2022

Introduction

HYDROCOASTAL is a two year project funded by ESA, with the objective to maximise exploitation of SAR and SARin altimeter measurements in the coastal zone and inland waters, by evaluating and implementing new approaches to process SAR and SARin data from CryoSat-2, and SAR altimeter data from Sentinel-3A and Sentinel-3B. Optical data from Sentinel-2 MSI and Sentinel-3 OLCI instruments will also be used in generating River Discharge products.

New SAR and SARin processing algorithms for the coastal zone and inland waters will be developed and implemented and evaluated through an initial Test Data Set for selected regions. From the results of this evaluation a processing scheme will be implemented to generate global coastal zone and river discharge data sets.

A series of case studies will assess these products in terms of their scientific impacts.

All the produced data sets will be available on request to external researchers, and full descriptions of the processing algorithms will be provided

 

Objectives

The scientific objectives of HYDROCOASTAL are to enhance our understanding  of interactions between the inland water and coastal zone, between the coastal zone and the open ocean, and the small scale processes that govern these interactions. Also the project aims to improve our capability to characterize the variation at different time scales of inland water storage, exchanges with the ocean and the impact on regional sea-level changes

 

The technical objectives are to develop and evaluate  new SAR  and SARin altimetry processing techniques in support of the scientific objectives, including stack processing, and filtering, and retracking. Also an improved Wet Troposphere Correction will be developed and evaluated.

 

Presentation

The presentation will describe the different SAR altimeter processing algorithms that are being evaluated in the first phase of the project, and present results from the evaluation of the initial test data set focusing on performance at the coast. It will also present the results of a study assessing regional tidal models.
Evaluating the hydrological regime of the snow-fed and glaciated Hunza basin in the Hindukush Karakorum Himalaya (HKH) region
Authors: Nazeer Aftab , Maskey Shreedhar , Skaugen Thomas , E. McClain Michael
Published: March 2022

In the high altitude Hindukush Karakorum Himalaya (HKH) mountainous region, the complex weather and terrain and sparse measurements make the precipitation distribution and hydrological regime significant unknowns. Recent advances in remote-sensing and reanalysis-based global precipitation products and numerical models may provide more insights on the hydro-climatic regimes for such regions. This study examined the precipitation distribution and snow and glacier melt contributions to river flow in the highly glaciated and snow-fed Hunza basin of the Karakorum mountains. The Distance Distribution Dynamics (DDD), a rainfall-runoff model with its temperature index and an energy balance approach for glacial melt, was used. The model was forced with precipitation estimates based on a newly developed and fine resolution (0.1°×0.1°) gridded product of ERA5-Land. The model calibration and validation were performed from 1997–2005 and 2006–2010, respectively. The mean annual precipitation of the Hunza basin was estimated as 947 mm from 1997–2010. The precipitation distribution analysis showed more precipitation at lower elevations than at higher. The simulated snow cover area (SCA) was in good agreement with MODIS satellite-based SCA. The flow analysis indicated that the Hunza’s flow is strongly controlled by glacier melt (44–47 %) followed by snowmelt (31–32 %) and rainfall (22–23 %). The simulations showed that the DDD model has good potential to simulate hydrological processes satisfactorily for data-scarce basins.
Evaluation of lipid biomarkers as proxies for sea ice and ocean temperatures along the Antarctic continental margin
Authors: Müller Juliane , Lamping Nele , Hefter Jens , Mollenhauer Gesine , Christian Haas , Shi Xiaoxu , Vorrath Maria-Elena , Lohmann Gerrit , Hillenbrand Claus-Dieter
Published: March 2022

Over the past decade, the highly branched isoprenoid (HBI) diene IPSO25 (Belt et al., 2016), has gained pronounced attention as a proxy for sea-ice reconstructions in Antarctica. Recent studies propose the additional consideration of phytoplankton-derived biomarkers such as certain sterols and/or tri-unsaturated HBIs to determine the so-called PIPSO25 index - a novel approach targeting on semi-quantitative sea ice estimates (Vorrath et al., 2019; Lamping et al., 2020). In order to further test and validate the reliability of this index and also to evaluate GDGT-based ocean paleothermometers in polar latitudes, we investigated several seafloor surface sediments from the Amundsen Sea, the Antarctic Peninsula and the Weddell Sea and compare the proxy-based sea-ice and ocean temperature reconstructions to satellite observations, instrumental measurements and modelling outputs (Lamping et al., 2021). We note the general capability of these proxies to determine oceanic key variables properly but also identify weaknesses associated with uncertainties regarding source specificity of certain lipids and existing calibrations.   

References

Belt, S.T., Smik, L., Brown, T.A., Kim, J.H., Rowland, S.J., Allen, C.S., Gal, J.K., Shin, K.H., Lee, J.I. and Taylor, K.W.R. (2016). Source identification and distribution reveals the potential of the geochemical Antarctic sea ice proxy IPSO25. Nature Communications 7, 12655.

Lamping, N., Müller, J., Esper, O., Hillenbrand, C.-D., Smith, J.A. and Kuhn, G. (2020). Highly branched isoprenoids reveal onset of deglaciation followed by dynamic sea-ice conditions in the western Amundsen Sea, Antarctica. Quaternary Science Reviews 228, 106103.

Lamping, N., Müller, J., Hefter, J., Mollenhauer, G., Haas, C., Shi, X., Vorrath, M.E., Lohmann, G. and Hillenbrand, C.D. (2021). Evaluation of lipid biomarkers as proxies for sea ice and ocean temperatures along the Antarctic continental margin. Clim. Past 17, 2305-2326.

Vorrath, M.E., Müller, J., Esper, O., Mollenhauer, G., Haas, C., Schefuß, E. and Fahl, K. (2019). Highly branched isoprenoids for Southern Ocean sea ice reconstructions: a pilot study from the Western Antarctic Peninsula. Biogeosciences 16, 2961-2981.
Callisto's atmosphere and its space environment: prospects for the Particle Environment Package on board JUICE
Authors: Galli André , Vorburger Audrey , Carberry Mogan Shane R. , Roussos Elias , Stenberg Wieser Gabriella , Wurz Peter , Föhn Martina , Krupp Norbert , Fränz Markus , Barabash Stas , Futaana Yoshifumi , Brandt Pontus C. , Kollmann Peter , Haggerty Dennis , Jones Geraint H. , Johnson Robert E. , Tucker Orenthal J. , Simon Sven , Tippens Tyler , Liuzzo Lucas
Published: March 2022

The JUpiter ICy moons Explorer (JUICE) of the European Space Agency will investigate Jupiter and its icy moons Europa, Ganymede, and Callisto, with the aim to better understand the origin and evolution of our Solar System and the emergence of habitable worlds around gas giants. The Particle Environment Package (PEP) on JUICE is designed to measure neutrals and ions and electrons at thermal, suprathermal, and radiation belt energies (eV to MeV). 

In the vicinity of Callisto, PEP will characterize the plasma environment, the outer parts of Callisto's atmosphere and ionosphere and their interaction with Jupiter's dynamic magnetosphere. About 20 Callisto flybys with closest approaches between 200 km and 5000 km altitude are
planned over the course of the JUICE mission. In this presentation, we review the state of knowledge regarding Callisto's ambient environment and magnetospheric interaction with recent modeling efforts for Callisto's atmosphere and ionosphere to identify science opportunities for the PEP observations and to optimize scientific insight gained from the foreseen JUICE flybys. These considerations inform science operation planning of PEP and JUICE and they will guide future model development for the atmosphere and ionosphere of Callisto and their interactions with the plasma environment.
New approach to water content measurements in soil core using microwave probing
Authors: Sabouroux Pierre , Sparma Floriane , Szypłowska Agnieszka
Published: March 2022

Abstract – A new approach for water content determination in an in situ soil at depths ranging from the soil surface down to a few meters in soil profile is under development. The concept of this method is based on a core drill that will be equipped with a multi-probe sensor working at  radio and  microwave frequencies. The objective of the presented research focuses on the study of the multi-probe sensor that was carried out on sandy soils and clay.

This solution is based on reflection and transmission measurements using several probes arranged on the circumference of a metal tube. The use of various probes allows us on one hand to detect thresholds of the water in soil and on the other hand to diagnose the homogeneity of the material under test. This sensor is incorporated in a test bench composed of a VNA and a Switch Matrix that allows the VNA to connect with the 6 probes of the sensor. The measurements are the reflection of each probe and the transmission between two identified probes in a band of frequencies between 100MHz and 12GHz.

The first series of measurements with the multiprobe sensor was carried out on sand containing 0 to 20% water with increments of 5%. From the reflection coefficient values of each probe and the transmissions between two respective probes, we were able to verify the variation related to the increase of the water content in the sand. This determination of the water content is made from the modulus of the reflection coefficient and the different cases of transmissions between two probes.

In conclusion, a new concept of a multi-probe sensor, for the determination of a soil moisture profile in the relatively loose and homogeneous sandy and clayey soil has been developed and tested. Thus, we were able to evaluate thresholds of water content in the sand of around 5% with this sensor. In order to continue the study of the sensor, we now plan to test more complex soils, but especially to extrapolate this multi-probe sensor to a system using a core drill to increase the depth of testing. This is a solution to characterize soils without sampling them. Especially, it is hoped that with the developed sensor a soil profile can be measured down to several meters in depth.

Acknowledgment : This work has been supported by the Polish National Agency for Academic Exchange under Grant No. PPI/APM/2018/1/00048/U/001.
Evolution of power spectral density of magnetic field fluctuations in the inner heliosphere
Authors: Safrankova Jana , Nemecek Zdenek , Nemec Frantisek , Durovcova Tereza , Franci Luca , Pitna Alexander
Published: March 2022

The solar wind is a unique laboratory to study the turbulent processes occurring in a collisionless plasma with high Reynolds numbers. The paper analyzes power spectra of magnetic field fluctuations that are computed in the frequency range around the break between inertial and kinetic scales. We use observations made during first nine Parker Solar Probe encounters and compare them with observations of the spacecraft moving in other distances from the Sun (e.g., Solar Orbiter) and closer to 1 AU (Wind). A preliminary analysis of magnetic field fluctuations based on PSP and Wind measurements from the MHD to kinetic scales has shown that a relative level of compressive fluctuations increases until 0.25 AU and remains constant till 1 AU whereas a relative level of perpendicular fluctuations does not change with the distance from the Sun. We can conclude that the B slope is controlled by different process(es) close to the Sun against 1 AU and that, in spite of expectations, the critical distance for turbulence evolution is as large as 0.25 AU. We also discuss the role of important physical parameters (e.g., ion beta, temperature anisotropy, collisional age, magnetic field fluctuation amplitude) determining the properties of the turbulent cascade in different heliospheric locations.
The Correspondence between Sudden Commencements and Induced Currents; Insights from New Zealand
Authors: Smith Andy , Rodger Craig , Mac Manus Daniel , Forsyth Colin , Rae Jonathan , Freeman Mervyn , Clilverd Mark , Petersen Tanja , Dalzell Michael
Published: March 2022

The impact of a solar wind pressure pulse on the Earth’s magnetosphere causes rapid changes in the surface geomagnetic field, often termed Sudden Commencements (SCs).  Such magnetic field changes can induce potentially damaging currents (GICs) in conducting infrastructure on the ground, and therefore represents a critical space weather hazard.  Unfortunately, GICs are not often measured directly.  Instead, large GICs are often inferred from easier-to-measure large magnetic perturbations.  In this work we examine the coupling between SCs and observed GICs in New Zealand, where both measurements are available.

Overall, we find excellent correlations between the maximum magnetic perturbations and GICs during SCs. Nevertheless, if the SC precedes a geomagnetic storm, then it is associated with 22% larger GICs, controlling for the size of the magnetic deflection.  Further, if the SC is observed when New Zealand is on the dayside of the Earth then the associated GICs are 30% greater.  We investigate these findings, and attribute them to the full vector directionality of the strongest magnetic field deflection and the full rate of change of the magnetic field of the SC, beyond that recorded in the one minute resolution data.

Finally, we show that based on the properties of the solar wind shock, a skilful prediction can be made as to whether an SC and/or a geomagnetic storm will be observed, which may be used to guide interpretation of the coupling between the magnetic deflection and GICs.
The foreshock wave activity under quasi radial magnetic field in lunar distances: Statistical study
Authors: Salohub Anna , Safrankova Jana , Nemecek Zdenek
Published: March 2022

We present a large statistical study of the ultra-low frequency (ULF) waves in the terrestrial foreshock. These waves are excited in the upstream region by energetic ions streaming along the solar wind magnetic field lines connected to the bow shock. Although these waves propagate upstream and grow in the solar wind frame, they are blown down by the solar wind flow and thus their amplitudes would grow toward the bow shock. In our previous study based on ARTEMIS observations, we demonstrated that the statistically determined growth rate is positive but also the cases of a wave decay are frequently observed. We have shown that even if a possible influence of the Moon and its wake is excluded, the growth rate is decreased by non-linear effects leading to a saturation of the wave amplitude. To eliminate this problem, we have selected intervals allowing identification of an initial stage of wave amplitude growth (either in spatial or temporal sense). Our study revealed that the growth rate depends on the wave type being larger for compressive variations of the magnetic field strength and plasma density than for variations of magnetic field components. The analogous study of velocity fluctuations leads to smaller growth rates and we discuss possible causes of this disagreement.
Laboratory Simulation of the Dust Interaction with Energetic Particles and its Implication for Interstellar medium
Authors: Pavlu Jiri , Wild Jan , Cizek Jakub , Nouzak Libor , Vaverka Jakub , Safrankova Jana , Nemecek Zdenek
Published: March 2022

Dust in the interstellar space is illuminated by cosmic radiation that consists of photons of different wavelengths and energetic charged particles. Whereas the photoemission is rather well understood, charging of dust grains due to interaction of with energetic charged particles was not experimentally studied in detail so far. We report the first laboratory experiment dealing with the interaction of a cosmic dust simulant with energetic charged particles emitted from a radioisotope. Measurements of the charge of micrometer silicate dust grains with an accuracy of one elementary charge revealed several processes leading to the dust charging. The observed average rate of charging events agrees well with prediction of a model based on the continuous slowing down approximation of energetic particles inside the grain. Charge steps larger than one elementary charge were attributed to emission of secondary electrons excited by the primary particle slowing down. The determined yield of secondary electron emission is approximately inversely proportional to the grain radius. The experimental results led us to the formulation of a possible scenario of interstellar dark clouds charging.
Alpha transmitter signals observed by the Van Allen Probes: Ducted vs. unducted propagation
Authors: Nemec Frantisek , Santolik Ondrej , Hospodarsky George B. , Kurth William S. , Kletzing Craig
Published: March 2022

Electromagnetic waves radiated by powerful military very low frequency transmitters can efficiently interact with energetic electrons trapped in the radiation belts and result in their precipitation. However, such interactions ultimately depend on the wave normal angles of propagating emissions. In the equatorial interaction region, these can be either very low (ducted propagation) or comparatively large (unducted propagation). It is thus important to be able to distinguish between the two propagation types and to quantify what portion of the wave energy propagates ducted/unducted. Unfortunately, spacecraft multicomponent wave measurements which would allow to directly experimentally tackle this issue typically do not extend to high enough frequencies with a sufficient frequency resolution. One exception that we exploit are signals from Alpha navigation transmitters, which radiate at frequencies as low as about 11.9 kHz. Such frequencies are readily detectable by the EMFISIS instrument onboard the Van Allen Probes spacecraft operating close to the geomagnetic equator at L-shells between about 1.1 and 6.5. We use respective multicomponent burst mode measurements to distinguish between the ducted and unducted modes of propagation and to evaluate their relative importance under different conditions. We show that while the unducted waves are detected more often, the ducted waves tend to have larger Poynting fluxes, so that the total power propagating in the two modes is roughly comparable.
Determination of electron and proton fluxes in a low Earth orbit with SATRAM and comparison to EPT data
Authors: Gohl Stefan , Bergmann Benedikt , Kaplan Martin , Nemec Frantisek
Published: March 2022

The Space Application of Timepix based Radiation Monitor (SATRAM) was launched in May 2013 onboard the Proba-V spacecraft into a low Earth orbit of 820 km. SATRAM has been measuring the radiation environment since then. Due to its pixelized structure, one can find properties in the particle tracks that identify those tracks as electrons or protons. The goal is to determine the electron and proton fluxes measured by SATRAM. The rather thick aluminium box surrounding the Timepix detector cuts off the low end of the energy spectrum for all particle species, limiting the energy range to 700 keV to 7 MeV for electrons and 15 MeV to 400 MeV for protons. For the particle identification, a neural network was utilized. It has an accuracy of about 90 % for both particle species. A Geant4 simulation was conducted to determine the efficiency of the detector for electrons and protons, respectively. Unfortunately, the proton fluxes cannot be measured that way, as the electron background is in the same order of magnitude as the number of protons. Alternatives are being discussed. Finally, the electron fluxes are compared with the data from the Energetic Particle Telescope (EPT) in the relevant energy range, which is also situated onboard the Proba-V satellite. The electron fluxes of both instruments agree with each other.
Pyrogenic carbon decomposition critical to resolving fire's role in the Earth system
Authors: Bowring Simon P.K. , Jones Matthew W. , Ciais Philippe , Guenet Bertrand , Abiven Samuel
Published: March 2022

Recently identified post-fire carbon fluxes indicate that in order to understand if global fires represent a net carbon source or sink, one must consider both terrestrial carbon retention through pyrogenic carbon (PyC) production, and carbon losses via multiple pathways. Here, these legacy source and sink pathways are quantified using a CMIP6 land surface model to estimate Earth's fire carbon budget. Over 1901-2010, global PyC drives annual soil carbon accumulation of 337 TgCyr-1, offset by legacy carbon losses totalling -248 TgCyr-1. The residual of these values constrains maximum annual pyrogenic carbon mineralisation to 89 TgCyr-1, and PyC mean residence time to 5387 years, assuming steady state.   However, paucity of observational constraints for representing PyC mineralisation mean that without assuming steady state, we are unable to determine the sign of the overall fire carbon balance. 

The residual is negative over forests and positive over grassland-savannahs (implying a potential sink), suggesting contrasting roles of vegetation in the fire carbon cycle. Without widespread tropical grassland-savannah coverage, the legacy effects of fires could not feasibly enhance terrestrial C storage -a result afforded by grasses’ capacity for fire recovery. The dependency of the fire C residual on vegetation composition suggests that the preservation/restoration of native grasslands may be an important vector for decreasing C losses from future fire activity. We call for significant investments in understanding of PyC degradation and its drivers, in addition to improved estimates of legacy fire C fluxes. Reliable quantification of PyC mineralisation and erosion, particularly over grasslands, remains the principal missing link in a holistic understanding of fire’s role in the Earth system.
The role of tropical cyclone size in precipitation over Mexico 
Authors: Perez Estrada Adolfo , Dominguez Sarmiento Christian
Published: March 2022

Tropical cyclones (TCs) from the North Atlantic and Eastern Pacific Ocean affect Mexico yearly. Their landfall  in the country produces not only water supply in semiarid regions, but also socioeconomic impacts in regions that are vulnerable to strong winds and heavy precipitation. The associated disasters have motivated the Mexican authorities to develop an Early Warning System for TCs (EWS-TC). However, this EWS-TC is still inefficient due to the definition of TC size (defined by the extension of winds at 34 knots, commonly called R34) and neglection of TC precipitation in the warnings. Here, we propose to use TC sizes that consider the TC rain bands, heavy precipitation and strong winds. To compute our TC size, we use a new parameterization of radial profile of winds and infrared satellite images, which leads to compute TC radii by quadrants, during the 2000-2020 period. We conclude that our TC size definition leads to better warnings than the use of R34. Suggestions on how resilience for facing TCs can be improved are also discussed.
New estimates of observed poleward freshwater transport since 1970
Authors: Sohail Taimoor , Zika Jan , Irving Damien , Church John
Published: March 2022

Global water cycle changes induced by anthropogenic climate change pose a growing threat to existing ecosystems and human infrastructure. However, scarce direct observations of precipitation and evaporation means historical water cycle changes remain uncertain. In this work, we apply a novel watermass-based diagnostic framework to the latest observations of ocean salinity to quantify poleward freshwater transport in the earth system since 1970. This observational estimate is not replicated in any model in the current generation of CMIP6 climate models - likely due to the inaccurate representation of surface freshwater flux intensification in such models. These results provide a first-of-its-kind baseline of observed warm-to-cold freshwater transport since 1970, and also underscore the need to further explore surface freshwater fluxes in existing climate models.
Particle path length estimation: a signal processing approach 
Authors: Capito Lindsay , Bizzi Simone , Surian Nicola , Bertoldi Walter
Published: March 2022

The structure and function of rivers is directly related to bedload transport which is difficult to measure due to its spatial heterogeneity and the logistic constraints of field measurements. These difficulties have given rise to the morphological method wherein sediment transport is inferred from changes in morphology and estimates of the distance traveled by sediment during a flood, its path length. However, current methods for estimating path length are time and labor intensive, have low recovery rates, and are limited to some morphological units. We propose a method to estimate path length from repeat digital elevation models (DEM’s of difference i.e. DoDs) which are requisite for the morphological method. We interpret the pattern of erosion and deposition downstream as a signal and apply Variational Mode Decomposition (VMD), a signal processing method, to quantify the periodicity as a proxy for path length. We developed this method using flume experiments with measured sediment flux and applied it to published field data with tracer measurements for validation. The preliminary results provide a range of values on the same order of magnitude as measured tracer and flux data and are coherent with channel geometry. This method provides a reasonable estimation of path length based solely on remotely sensed data and a range of plausible sediment fluxes associated with specific channel morphological processes through DoD interpretation.
Inducing Enantiomeric Imbalance with Spin Polarized Electrons
Authors: Ozturk Sukru Furkan , Sasselov Dimitar
Published: March 2022

Biologically important molecules like sugars and amino acids are chiral--they exist in mirror symmetrical pairs that cannot be superimposed on each other. However, in living organisms this so-called chiral symmetry is broken and right handed sugars and left handed aminoacids are selectively used by life. The mechanism behind this chiral symmetry breaking yet remains elusive. Here we propose spin-polarized electrons as the symmetry breaking agent which are shown to induce enantioselective chemistry due to chiral induced spin selectivity (CISS) related phenomena. We consider spin-polarized electrons ejected from a magnetized surface by UV irradiation and their role in inducing chirally selective reactions in cyanosulfidic chemistry. We outline the geochemical formation and magnetization of magnetite deposits that can provide the magnetized surface. We further discuss the possible role of magnetic field generated by the ferromagnetic deposits on prebiotic chemistry due to spin effects such as radical-pair and triplet mechanisms.
A tale of two plutons: Compositional control on weathering, erosion, and landscape morphology
Authors: Lodes Emma , Scherler Dirk
Published: March 2022

While lithological differences are well known to affect the morphology of landscapes, less is understood about how subtle differences in the composition of granitoid bedrock may affect weathering, erosion, and landscape evolution. Here, we investigate a landscape in the semi-arid Coastal Cordillera of Central Chile, whose bedrock is made up of two plutons of differing composition; a monzogranite and a diorite/gabbro. The landscape underlain by the diorite/gabbro appears to consist of taller hills and a lower drainage density compared to the landscape underlain by the monzogranite, which appears to be characterized by smaller hills and a higher drainage density. We hypothesize that the contrast in landscape morphology is related to differential weathering rates, due to the mineralogical compositions of the underlying bedrock. Most importantly, differences in feldspar composition can affect dissolution rates as potassium-rich feldspars are less weatherable than calcium- and sodium-rich feldspars. To test our hypothesis, we obtained the major oxide composition of the bedrock using X-Ray Fluorescence and measured in situ cosmogenic 10Be to obtain denudation rates of bedrock and soils. We also measured surficial sediment grain sizes, and conducted topographic analysis of the landscape using a 1-m resolution digital elevation model (DEM). Preliminary results suggest that the surface sediments of the monzogranite have – on average – a smaller grain size, and the chemical composition of the bedrock shows higher levels of SiO2 and K2O, and lower levels of Na2O and CaO, compared to the gabbro/diorite. DEM analysis supports our field impression and indicates significant differences in drainage density between the two plutons. In addition, 10Be results so far suggest similar erosion rates between the two plutons. We plan to further investigate the mineralogy using thin sections obtained from bedrock outcrops and obtain more field measurements.
Evaluation of the water response in a Mediterranean karstic catchment (SE Spain) with the SIMPA and SWAT models
Authors: Jodar Antonio , Palacios - Cabrera Teresa , Bailey Ryan T. , Melgarejo - Moreno Pablo , Legua - Murcia Pilar , Hussein Enas E.
Published: March 2022

Abstract:

Hydrological modelling in karst environments is a difficult task due to the inherent complexity of the karst system and the usual lack of information about its geometrical description. The hydrological processes of karst systems in Mediterranean semiarid environments are particularly difficult to simulate mathematically due to the pattern of long dry periods and short wet periods. In this study, we tested the ability of the open-source SWAT hydrologic modelling code to simulate the behaviour and hydrologic output of a karstic watershed in a Mediterranean semiarid environment (SE Spain). Calibration and first validation were accomplished using a 20-year and 10-year record of stream water discharge, respectively, at the catchment outlet. Additional testing of the model was accomplished using groundwater discharge data from four natural springs in the watershed and by comparing the results of the SWAT model with the SIMPA model (a hydrological model used by the Spanish national water authority to simulate the water balance among others). Likewise, an adapted form of the Nash-Sutcliffe Efficiency (NSE) index for arid environments, ANSE, is presented. Based on results, the simulated behaviour was good and very good (with ANSE values of 0.96 and 0.78 for the calibration and validation periods respectively). SWAT and SIMPA results provide spatial distributions of the main hydrological processes of the watershed, such as aquifer recharge, actual evapotranspiration, and surface runoff, being verified as useful tools for water policy managers in karstic environments.

Keywords:

Water balance; karst aquifer springs; SWAT; SIMPA; ANSE index; Mediterranean karstic catchment.

 

 

 

 
The preliminary realization and evaluation of BDS3 global terrestrial reference framework (CTRF2020)
Authors: ren yingying , wang hu , wang jiexian
Published: March 2022

The current international and regional reference frame research is mainly realized by single GPS (Global Position System) technology. With the full deployment of BDS (Beidou Navigation System), it is urgent to study and establish the corresponding terrestrial reference frame. Since 2019, the global and regional BDS service performance has been evaluated and tested, and the long-term BDS observations of MGEX (Multi GNSS Experiment) sites distributed worldwide provide the possibility for the preliminary construction of the BDS terrestrial reference frame. We aim to preliminarily realize and evaluate the CTRF2020 (COMPASS/BDS Terrestrial Reference Frame at the epoch of 2020.0) that can be expressed with the coordinates and velocities of a series of reference sites at the epoch of 2020.0. Firstly, the actual BDS global service performance evaluation reflects BDS satellite's high visibility and change trend in recent three years, which provides primary input data for the frame. Then, the BDS observations of about 100 global sites in the recent three years are calculated by PPP (Precise Point Positioning) and NET solution, to obtain the global high-precision BDS coordinate time series. Then, the BDS time series of the two solutions are fitted and compared with the IGS14 velocity field. The results show that the series accuracy of PPP-BDS and NET-BDS solutions is equivalent, and there is an mm-level systematic deviation with IGS14 solutions. The horizontal series fitting accuracy of PPP-BDS and NET-BDS solutions is better than that of the vertical direction, the accuracy of NET-BDS solution is slightly better than PPP-BDS, and the difference of fitting accuracy is 0.12, 0.13, and 0.50 mm in the NEU direction. The velocity field accuracy of PPP-BDS and NET-BDS solution is the same, and the overall three-dimensional velocity difference is less than 0.2 mm/a. The velocity fields of PPP-BDS and NET-BDS solution have little difference from IGS14, and the overall difference is less than 0.5 mm/a. Finally, we give the limitations and improvement points of CTRF2020. The preliminary realization and evaluation of CTRF2020 may be expected to provide a reference for the future realization of a comprehensive terrestrial reference framework dominated by BDS technology and supplemented by multi-source space geodetic technology.
Linkages between soil micro-food webs and agroecosystem multifunctionality under organic and/or inorganic fertilization
Authors: Zhao Jie , Li Jiangnan , Wang Kelin
Published: March 2022

Reducing chemical fertilizers and agricultural residues substitution is a feasible practice to develop sustainable agriculture. However, there is a lack of evaluation on the ecosystem functioning and services of different reducing chemical fertilizers and agricultural residues substitution practices, as well as the roles of soil micro-food webs in sustainable agriculture. Here, we evaluated changes in crop yields, soil physico-chemical properties, soil micro-food web assembly, and ecosystem multifunctionality, and the contribution of soil micro-food web assembly to ecosystem multifunctionality under six long-term fertilization treatments: no fertilizer control, conventional chemical NPK fertilizers, and the reducing chemical NPK fertilizers and low- (30%) or high- (60%) levels of agricultural residues (i.e., straw or cattle manure) substitution. Our results showed that the reducing chemical fertilizers and agricultural residues substitution practices can maintain crop yields and improve soil fertility compared with chemical fertilizers application alone. The improvement of soil micro-food web was more obvious with the reducing chemical fertilizers and agricultural residues substitution practices, such as increased soil bacterial biomass, maintained soil biodiversity, and mitigated the negative effects of long-term chemical fertilizers application alone on soil micro-food web. More importantly, maintaining soil bacterial biomass, especiallly the beneficial microorganisms (e.g., Proteobacteria and Firmicutes), and bacterivorous nematode abundance is primarily important in  maintaining ecosystem multifunctionality. Overall, the reducing chemical fertilizers and agricultural residues substitution practices improved agroecosystem functioning and services and contributed to sustainable agriculture. 
Seismic anisotropy structure of the northern Hikurangi margin, New Zealand, and its significance for subduction fault systems
Authors: Arai Ryuta , Kodaira Shuichi , Henrys Stuart , Bangs Nathan , Obana Koichiro , Fujie Gou , Miura Seiichi , Barker Daniel , Bassett Dan , Bell Rebecca , Mochizuki Kimihiro , Kellett Richard , Stucker Valerie , Fry Bill
Published: March 2022

The NZ3D OBS experiment performed in 2017-2018 in the northern Hikurangi margin off the east coast of North Island, New Zealand, provided the highest-resolution seismic refraction/wide‐angle reflection data with multi-azimuth ray coverage in subduction zones to date (Arai et al., 2020). The study area extending 60 km in the trench-normal direction and 14 km in the trench-parallel direction covers source regions of a variety of slow earthquake phenomena, such as shallow slow slip events and tectonic tremor (e.g., Wallace, 2020), and thus offers an ideal location to link our understanding of structural and hydrogeologic properties at subduction faults to slip behavior. We applied an anisotropic traveltime tomography analysis to this active-source dataset from 97 ocean bottom seismographs deployed with an average spacing of 2 km on four parallel lines and dense air gun shooting with a 25 m interval, and succeeded in quantitatively constraining the P-wave velocities (Vp) of the upper plate forearc and the subducting slab and their azimuthal anisotropy in three dimensions. The velocity models revealed some locations with significant Vp azimuthal anisotropy over 5 % near the splay faults in the low-velocity accretionary wedge and the deformation front. This finding suggests that the anisotropy is not ubiquitous and homogeneous within the upper plate, but more localized in the vicinity of active thrust faults. While the fast axes of Vp are mostly oriented in the trench-normal direction in the accretionary wedge, which is interpreted as results of preferentially oriented cracks in a compressional stress regime associated with the plate convergence, they are rotated to the trench-parallel direction on the seaward side of the trench and in the landward backstop. This regional variation is consistent with the results of shear-wave splitting analysis (Zal et al., 2020) and the directions of maximum horizontal stress inferred from the borehole breakouts at two IODP drilling sites (Wallace et al., 2019). The significant magnitudes of anisotropy may indicate that in addition to the crack orientation, clay-rich sedimentary sequences that stack and form coherent strata along the accretionary wedge also contribute to seismic anisotropy in the subduction margin.

 
Deep-UV Broadband Cavity-Enhanced Absorption Spectroscopy: application to sensitive real-time detection of the aromatic pollutants Benzene, Toluene, and Xylene (BTX)
Authors: Wang Meng , Varma Ravi , Venables Dean , Zhou Wu , Chen Jun
Published: March 2022

Benzene, toluene and xylene (BTX) are serious air pollutants emitted by the chemical industry. Real-time monitoring of these air pollutants would be a valuable tool to regulate emissions of these compounds and reduce the harm they cause to human health. Here we demonstrate the first detection of BTX using Incoherent Broadband Cavity Enhanced Absorption Spectroscopy (IBBCEAS). The instrument was operated in the deep-ultraviolet spectral region between 252 and 286 nm, where aromatic compounds have intense  π→π*  absorption bands. The mirror reflectivity was calibrated by two methods and exceeded 99.63% at 266 nm. At an integration time of 60 s, the 1σ measurement sensitivity was estimated to be 1.4 ppbv (1σ) for benzene, 8.7 ppbv (1σ) for toluene, 7.3 ppbv (1σ) for m-xylene and 3.0 ppbv (1σ) for p-xylene, respectively. The absorption cross-sections of BTX were measured in this work with an uncertainty of 10% at a resolution of 0.74 nm and were in good agreement with earlier studies, after accounting for differences in spectral resolution. To demonstrate the ability of the instrument to quantify complex mixtures, the concentrations of m-xylene and p-xylene were retrieved under five different mixing ratios. The IBBCEAS approach allows real time, in situ measurements with high selectivity, and may be valuable in applications not suited to long-path approaches like DOAS. Instrumental improvements and strategies for different atmospheric and analytical applications are discussed.
Fungal mycelium growth: effects of the sand particle size
Authors: Zuev Andrey
Published: March 2022

In-growth mesh bag technique is widely used for assessing production and turnover of the fungal mycelium in soil, but remains poorly standardized. Various filling materials are used mainly quartz sand with particle size range of 0.4–2.0 mm or 0.5–1.5 mm. Substrate particle size plays a crucial role in soil pore formation: larger pore space may increase the growth of mycelium that spreads along cracks and other air-filled pores In contrast, the volume of soil explored by fungi can increase with greater bulk density while mycelium allocation shifts from a few large pores to more evenly distributed small pores. This research was aimed at testing the use of quartz sand of different particle size, as a filling for in-growth mesh bags, in order to obtain a maximum amount of fungal mycelium. Mesh bags were incubated in a Norway spruce forest in Central Russia. Mycelial biomass was higher in sand of coarse (> 0.5 mm) particle size and reached maximum (up to 798 μg of mycelium dry weight g−1 sand).