bluuebunny/crossref_metadata_2025 huggingface dataset:
Climate linkages between fire, population, and agriculture in the Maya lowlands
Authors: Keenan Benjamin , Johnston Kevin , Breckenridge Andy , Douglas Peter
Published: March 2022

Understanding past societal responses to climate change requires proxy indicators of human population, climate and land-use change. We apply a range of proxies to a lake sediment core from Laguna Itzan, a cenote adjacent to the ancient Maya population centre of Itzan, in order to examine the response of the lowland Maya to climatic and environmental change, which remains poorly understood. By combining molecular proxies for population (faecal stanols) and biomass burning (polycyclic aromatic hydrocarbons or PAHs) with isotopic analyses of plant wax n-alkanes as proxies for vegetation change (δ13C) and palaeohydrology (δ2H), we show the complex interplay of environmental and societal changes over 3300 years.

Leaf wax hydrogen isotope records show that drought between ca. 750 and 900 CE, thought to have been responsible for societal collapse or transformation across the Maya lowlands, is not expressed in the catchment of Itzan. This likely reflects spatial variability in the magnitude and timing of climate change. Population decline at Itzan may have been a result of instability caused by drought from other areas as a result of military incursions or through climate migration/an influx of climate refugees, pressures between neighbouring polities, or disruptions to trade networks or regional food production systems.

Leaf wax carbon isotope ratios indicate brief intervals of intensive maize agriculture, generally associated with wet periods, but this expansion of maize agriculture is not long lasting, and often returns to baseline levels of C4 plant abundance. In addition to the earlier presence of humans at this site than currently indicated in the Itzan archaeological record based on the abundance of faecal stanols, we infer cultivation of maize around 4000 year BP, and potentially earlier. Further, analysis of the distribution of polycyclic aromatic hydrocarbons suggests that fire in the catchment transitioned over the past 3500 years from intense fires associated with slash and burn, or swidden, agriculture to a less intense fire regime following initial land clearance.

Our data indicate that human population dynamics and patterns of land clearance for agriculture varied substantially throughout the sediment core record, and that palaeoclimatic change may have driven these patterns. 
Spatial variation of runoff depth and sediment yield in relation to dominant Factors on the Tibetan Plateau
Authors: Zhang Fan , Zeng Chen , Wang Guanxing , Wang Li , Shi Xiaonan
Published: March 2022

The riverine runoff and sediment are essential carriers for nutrients and pollutants delivery and are considered as important indicators of land degradation and environmental changes. With growing interest in environmental changes over the Tibetan Plateau, this study investigated mean annual runoff depth and sediment yield from eight headwater catchments in relation to dominant factors such as annual precipitation, air temperature, and glacier area ratio, etc. Results show that runoff depth (Q) is positively correlated with both precipitation (P) and temperature (T), indicating combined water supply from rainfall and meltwater, increase of which may exceed the evapotranspiration water loss caused by temperature raise. Sediment yield (S) shows an inverted parabolic relationship with precipitation and at the same time positive correlation with glacier area ratio (Ag). The variation in sediment yield with precipitation can be explained by the operation of two factors, i.e., rainfall erosive action that increases continuously with increase in precipitation, and vegetation protective action that is unity for zero precipitation and decreases with increases in precipitation. 
Distribution of Active Seismic Deformation in the Eastern Alps from the Recent Swath-D Experiment
Authors: Hofman Rens , Kummerow Joern , Cesca Simone , Wassermann Joachim , Plenefisch Thomas ,   AlpArray Working Group
Published: March 2022

The Swath-D network was a temporary seismic experiment nested within the AlpArray backbone network. Roughly 150 broadband stations were deployed across the Austrian-Italian border in the Eastern Alps during the second half of 2017, and were active to late 2019. This dense network provided an unprecedented resolution in a tectonically active region that is considered to play an important role in the evolution of the Alps. Extracting new information from this dataset turned out to be challenging due to the large volume of the dataset, low magnitude of the seismicity, and heterogeneity of the study area.

We applied waveform-based methods to detect, phase-pick, and relocate seismic events using data from the Swath-D network in the Eastern Alps. A GPU-accelerated template matching algorithm was developed in order to increase the number of detected earthquakes based on the previously known seismicity. Newly detected events were automatically picked using based on waveform similarity, and precisely relocated. This poster provides an overview of our results and the methods that we have applied.
Investigation of Air-Bubble Screen on Reducing Scour in River Facility
Authors: Liao Kuo-Wei , Wang Zhen-Zhi
Published: March 2022

This study proposes an innovative idea to reduce scour in river structures via air-bubble screens, which does not provoke a significant impact on the ecological environment. Check dam is one of the most popular river facilities and is selected as the research target of this study. The scouring problem on the downstream side of check dam may damage its own safety and therefore, preventing the check dam from souring has been a challenge task for years. To lessen the safety impact from scouring, the existing methods often rely on using reinforced concrete structures that often, does not solve the problem but induces a series of scouring problem. Further, reinforced concrete structure may damage the river ecological environment during and after the construction. On the other hand, air-bubble screen may provide an alternative solution in solving the scouring problem without interrupting the environment. A scaled-check dam model using flume channel at Hydrotech Research Institute in NTU is conducted, and then the FLOW-3D is used to carry out numerical simulation to evaluate the effectiveness of the air-bubble screen in reducing the depth and range (or volume) of the scours. Results shown that air-bubble screen is able to effectively reduce the check dam scours. Based on results from experiments and simulations, the design principles for air-bubble screen are provided as a reference for future practice. 
Large deformation field from InSAR during 2015 to 2021 for the Makran subduction and North Tibet
Authors: Lv Xiaoran , Amelung Falk , Shao Yun , Wu Xiaoyong
Published: March 2022

We have calculated the deformation velocity field for the Makran subduction and North Tibet region with the spatial range of [25°N - 31°N; 55°E-67°E] and [30N°-41°N; 85°E-97°E], respectively. There are two significant deformation signals in the epicenter of the 2013 Mw 7.7 Balochistan earthquake and the 2001 Mw 7.8 Kokoxili earthquake. For the Balochistan earthquake, we found that the 7-year post-seismic deformation was due to the widespread aseismic slip along the megathrust and not due to the viscoelastic relaxation. For the Kokoxili earthquake, we probed whether the viscoelastic relaxation of 2001 Kokoxili earthquake is still continuing. We first simulate the deformation caused by the interseismic slip along the major active faults in Tibet. By comparing the simulated deformation and the observed deformation, we found the maximum ratio of the simulated deformation to the observation is 42%, which means that the viscoelastic relaxation of 2001 Kokoxili earthquake is still continuing. The effective viscosities of lower crust and upper mantle are inverted as 1.78*1019Pas and 1.78 * 1020Pas, respectively.
Ab initio investigation of the intercrystalline mechanical behavior of ferropericlase at extreme pressures of planetary mantles
Authors: Ritterbex Sebastian , Tsuchiya Taku
Published: March 2022

            Ferropericlase is the second most abundant phase of Earth’s lower mantle and is also considered to be one of the main constituents of the mantles of super-Earth exoplanets. Since ferropericlase is more ductile compared to silicates (Girard et al. 2016), it is expected to control the rheological behavior of mantle aggregates which governs solid-state convection of planetary mantles. The mechanical behavior of polycrystalline aggregates is strongly affected by the presence of grain boundaries. Despite previous work on MgO grain boundaries (e.g. Verma & Karki 2010; Hirel et al. 2019), little is yet known about the properties and mobility of ferropericlase grain boundaries at pressure conditions of deep planetary interiors.

            In this study, we carried out atomistic simulations based on the density functional theory to model the structures, energies and spin states of iron of a series of [001] symmetrical tilt grain boundaries in ferropericlase as a function of pressure. Based on these results, we investigated the mechanical behavior of the Σ5 tilt grain boundary by applying simple shear increments to the simulation cell to trigger grain boundary migration. Here, we will present the different mechanisms of grain boundary migration and the evolution of the ideal shear strengths up to a pressure of 400 GPa. Our results show that the mechanical strength of the grain boundaries and the directionality of their motion strongly varies with increasing pressure. Especially at pressure conditions of super-Earth exoplanets, significant grain boundary weakening is observed with increasing depth.  Implications for the deformation of ferropericlase at conditions of Earth’s and super-Earth’s mantles will be finally discussed.
Which planets best liberate phosphate for prebiotic chemistry?
Authors: Walton Craig , Shorttle Oliver , Jenner Frances , Pasek Matthew
Published: March 2022

Conditions at the surface of terrestrial type worlds inhabitable by Earth-like life are hugely variable. Earth itself has explored much of this extensive parameter space over time, as evidenced via the rock record, which contains evidence of both multi-million year global glaciations as well as hot house conditions. The area of emergent land,  the partial pressure of atmospheric carbon dioxide, and the geochemistry of crustal rocks have all evolved, and imply that terrestrial type exoplanets may be extremely diverse. Unfortunately, all of these parameters remain uncertain for Earth during the Era of Prebiotic chemistry. Understanding how the availability of critical molecules for prebiotic chemistry vary as a function of planetary conditions is therefore crucial for constructing self-consistent scenarios for the origin of life. We focus on phosphate, modelling 1) mineral hosts in crustal rocks, 2) the weathering of those minerals as a function of atmospheric composition, 3) the lithological composition of continental crust, 4) the ratio of continental crust to oceanic crust, 5) the ratio of emergent to submerged crust, and 6) the efficiency of sedimentary crustal reworking. Recent work has suggested that phosphate may be most available on worlds with high atmospheric pCO2, where abundant dissolved inorganic carbon in surface waters can help solubilise the P-bearing phase apatite.  Provocatively, our modelling suggests that, on primitive worlds where apatite is rare, the weathering of rock-forming silicate and carbonate minerals may supply higher P fluxes - up to an order of magnitude higher than weathering of apatite rich crust at low pCO2, and roughly competitive with or, for mafic crust rich in basaltic glass, 1-2 orders of magnitue higher than the weathering of apatite rich crust at high pCO2. Finally, our results also strongly suggest that high rates of sedimentary reworking are needed to access the highest P weathering fluxes on Earth-like worlds. Our results point towards settings of active sedimentary cycling as crucial for fuelling prebiotic chemistry with endogenous P sources, and reveal a broad mineralogical and climatic parameter space for Earth-like worlds under which that chemistry may have plausibly taken place.
Jet waveguides - links to persistent surface weather and sub-seasonal predictability
Authors: Romppainen-Martius Olivia , Kornhuber Kai , Tuel Alexandre , Wehrli Kathrin , White Rachel , Wirth Volkmar
Published: March 2022

Midlatitude synoptic-scale Rossby waves propagate along narrow bands of enhanced potential vorticity gradients co-located with the jet streams – the jet waveguides. These waveguides influence where and how efficiently the waves can propagate. The structure and location of the waveguides further affects how boundary wave forcing e.g., from the tropics or the surface forces and interacts with the midlatitudes waves. Very persistent waveguides can lead to persistent surface weather, a recent example is the flow situation over the Atlantic in summer 2021. Persistent waveguides potentially offer increased sub-seasonal predictability.

Alas, the story becomes more complicated as the jet waveguides do not exist in isolation, but rather form in response to midlatitude dynamics and boundary forcing and these two-way interactions need to be considered when investigating sub-seasonal predictability. This overview presentation will introduce the key characteristics of the jet waveguides, provide some illustrative examples and close with an overview of open questions and suggestions for ways forward. 
Interhemispheric Conjugacy of Concurrent Onset and Poleward Traveling Geomagnetic Responses for Throat Aurora Observed Under Quiet Solar Wind Conditions
Authors: Feng Hui-Ting , Han De‐Sheng , Chen Xiang‐Cai , Liu Jian‐Jun , Xu Zhong‐Hua
Published: March 2022

Throat auroras frequently observed near local noon have been confirmed to correspond to magnetopause indentations, but the generation mechanisms for these indentations and the detailed properties of throat aurora are both not fully understood. Using all‐sky camera and magnetometer observations, we reported some new observational features of throat aurora as follows. (1) Throat auroras can occur under stable solar wind conditions and cause clear geomagnetic responses. (2) These geomagnetic responses can be simultaneously observed at conjugate geomagnetic meridian chains in the Northern and Southern Hemispheres. (3) The initial geomagnetic responses of throat aurora show concurrent onsets that were observed at all stations along the meridians. (4) Immediately after the concurrent onsets, poleward moving signatures and micropositive bays were observed in the X components at higher‐ and lower‐latitude stations, respectively. We argue that these observations provide evidence for throat aurora being generated by low‐latitude magnetopause reconnection. We suggest that the concurrent onsets reflect the instantaneous responses of the reconnection signal arriving at the ionosphere, the followed poleward moving signatures reflect the antisunward dragging of the footprint of newly opened field lines, and the micropositive bays may result from a pair of field‐aligned currents generated during the reconnection. This study may shed new light on the geomagnetic transients observed at cusp latitude near magnetic local noon.
Open access to Dutch Earth scientific research labs and data through EPOS-NL
Authors: Pijnenburg Ronald , Wessels Richard ,   EPOS-NL team
Published: March 2022

Top research into the geo-societal challenges of our densely populated planet requires optimized use of available research data, facilities, and funds. Such optimization is the main aim of the European Plate Observing System – Netherlands (EPOS-NL): the Dutch research infrastructure for solid Earth sciences. EPOS-NL provides free of charge, (inter)national access to a unique cluster of large-scale, geophysical labs and data centers at Utrecht University (UU), Delft University of Technology (TU Delft) and the Royal Netherlands Meteorological Institute (KNMI). Lab access can be requested by applying to one of our biannual calls. EPOS-NL labs that can be accessed include A) The Earth Simulation Laboratory at UU and the Petrophysics laboratory at TU Delft, where experimental rock physics and analogue modelling studies can be performed on the fundamental processes that govern the deformation and transport behavior of the Earth’s crust and upper mantle; and B) The Multi-scale Imaging and Tomography (MINT) facilities, distributed over UU and TU Delft. MINT provides unprecedented capabilities in 2D and 3D imaging and microchemical and crystallographic mapping, down to a resolution of several nanometers. EPOS-NL further works with data centers, researchers and industry to improve open access to essential Earth scientific data and models. These include key data relating to the seismogenic Groningen gas field in the Netherlands, notably Distributed Strain Sensing data of the gas reservoir, a Petrel geological reservoir model, developed by the field operator NAM (Nederlandse Aardolie Maatschappij), and a vast amount of seismological data maintained by the ORFEUS Data Centre. Access is provided in the framework of the European infrastructure EPOS, cf. FAIR (Findable, Accessible, Interoperable and Reusable) data principles. In that way, EPOS-NL contributes to shared and cost-effective research into the geo-societal challenges faced by our densely populated planet. See www.EPOS-NL.nl for more information.
Experimental Study on the Efficiency of a Hydrosuction System for Desilting Sediment from a Farm Pond
Authors: Lai Tung-Yang , Hsu Yu-Chao , Wang Ji-Shang , Su Yu-Wen , Fu Guei-Lin , Hung Cheng-Yi
Published: March 2022

Sedimentation has been a crucial problem in the management of storage in farm ponds, which cuts down the capability of ponds in aspects of irrigation, flood detention, and water retention. The Hydrosuction sediment removal system features low energy consumption and reduction of structural modifications to the existing shaft, which is an economically feasible method to remove siltation in storage areas. However, the effect of desilting might be limited due to the position of inflow orifice of siphon-type pipe which controls the scope of desilting affected area. This study aims to enhance the desilting effect of a fixed siphon system through connected a designed drainage tube.

The experiments were conducted in a cubic tank with a volume of 1.0 m3. Inside the tank, a vertical square shaft with the height of 80cm connected to an outlet channel was placed, and the siphon-type pipe was arranged from the inner of the tank to the outlet channel along with the shaft with a 3.0 cm inner diameter. The tests were performed in two kinds of inflow conditions in three water heights (60, 70, 80 cm), one is constant head inflow condition for continuous inflow provided, the other is falling head inflow condition with limited inflow supply. The initially deposited depths of sediment varied from 30 or 40cm. The designed 24cm long tube which has three added upward orifices with two types of diameters (1.0, 2.0 cm) could be connected to the inflow orifice of the siphon pipe to compare the desilting effect with the original arrangement in the above flow conditions.

The experimental results revealed that the effect of desilting was promoted by the connection of the designed tube to the siphon system. Besides, the efficiency of desilting was affected by the sizes of discharge orifices on the designed tube in different inflow conditions. In the constant head inflow condition, the arrangement of the connected 2cm discharge orifice tube performed better results due to the larger amount of outflow induced by the larger orifice. On the contrary, the arrangement of the connected 1cm discharge orifice tube had better desilting effect in falling head inflow condition induced by the longer time of disturbance between flow and sediment in smaller discharge. The results indicate that the capability and efficiency of sediment removal in the siphon system might be promoted by connecting an extended drainage tube with an appropriate size of upward discharge orifices.
Spatial changes in nitrogen inputs drive short- and long-term variability in global N2O emissions
Authors: Harris Eliza , Yu Longfei , Wang Yingping , Mohn Joachim , Henne Stephan , Bai Edith , Barthel Matti , Bauters Marijn , Boeckx Pascal , Dorich Chris , Farrell Mark , Krummel Paul , Loh Zoe , Reichstein Markus , Six Johan , Steinbacher Martin , Wells Naomi , Bahn Michael , Rayner Peter
Published: March 2022

Anthropogenic activities, particularly fertilisation, have resulted in significant increases in nitrogen in soils globally, leading to negative environmental impacts including eutrophication, acidification, poor air quality, and emissions of the important greenhouse gas N2O. Potential changes in terrestrial N loss pathways driven by global change and spatial redistribution of N inputs are highly uncertain. We present a novel coupled soil-atmosphere isotope model (IsoTONE; ISOtopic Tracing Of Nitrogen in the Environment) to quantify terrestrial N losses and N2O emissions and emission factors for the period 1850-2020. The soil module is initialised using a global isoscape of natural soil δ15N values generated from measurement data using an artificial neural network. The model is optimized within a Bayesian framework using a high precision tropospheric time series of N2O isotopic composition as well as emission factor measurements from many sites across the globe.

N inputs from atmospheric deposition caused the majority (51%; 3.6±0.3 Tg N2O-N a-1) of total anthropogenic N2O emissions from soils (7.1±0.9 Tg N2O-N a-1) in 2020. Growth in total and anthropogenic soil N2O emissions over the past century was driven by both fertilization and deposition, however N inputs from biological fixation were responsible for subdecadal variability in emissions. N2O emission factors show large spatial variability due to climate and soil parameters. The mean global EF for N2O weighted by N inputs was 4.3±0.3% in 2020, much higher than the land surface area-weighted mean of 1.1±0.1%, as a large proportion of N inputs were in regions with relatively high emission factors. Climate warming as well as redistribution of fertilisation inputs have led to an increase in global EF for N2O over the past century; these additional emissions account for 18% of the total anthropogenic soil flux in 2020. Predicted increases in fertilisation in emerging economies will accelerate N2O-driven climate warming in the coming decades, unless targeted mitigation measures focussing on fertiliser management in developing regions are introduced.
Resolving the horizontal direction of internal tide generation: Global application for the first mode M2-tide
Authors: Nycander Jonas , Pollmann Friederike
Published: March 2022

Breaking internal tides contributes substantially to small-scale turbulent mixing in the ocean interior and hence to maintaining the large-scale overturning circulation. How much internal tide energy is available for ocean mixing can be estimated by using semi-analytical methods based on linear theory. Until recently, a method resolving the horizontal direction of the barotropic-to-baroclinic energy transfer was lacking. We here present the first global application of such a method for the first vertical mode of the principal lunar semi-diurnal tide. The conversion rate estimates are in general agreement with those obtained in previous studies, albeit somewhat smoother since the non-locality of the internal tide generation problem is taken into account more strongly. An advantage is that the conversion rate is positive definite with the new method. We also show that the effect of supercritical slopes on the modally decomposed internal tides is different than previously suggested. To deal with this the continental shelf and the shelf slope are masked in the global computation. The result shows that the energy flux can vary substantially with direction depending on the shape and orientation of topographic obstacles and the flow direction of the local tidal currents. Taking this additional information into account in tidal mixing parameterizations could have important ramifications for vertical mixing and water mass properties in global numerical simulations.
The Response of a Baroclinic Anticyclonic Mesoscale Eddy to Relative Wind Stress Forcing
Authors: Wilder Thomas , Zhai Xiaoming , Joshi Manoj , Munday David
Published: March 2022

Including the ocean surface current in relative wind stress is known to damp mesoscale eddies through a negative wind power input. This is thought to have potential ramifications for eddy longevity. Here, we study the spin-down of a baroclinic anticyclonic eddy subject to absolute and relative wind stress forcing by employing an idealised high-resolution numerical model. To assess the effect of relative wind stress on the eddy, we examine wind-induced vertical motions and energetics. Results from this study show that relative wind stress damps eddy kinetic energy (EKE) at the eddy’s surface. However, relative wind stress also induces additional vertical motions, in the form of Ekman pumping, that increases baroclinic conversion i.e., a conversion of potential to kinetic energy. When horizontally integrated, this additional baroclinic conversion by relative wind stress is positive throughout the eddy water column. The positive baroclinic conversion in the lower depths of the eddy leads to an increase in deep EKE, relative to the absolute wind stress case. In fact, over the eddy volume, the damping of EKE by relative wind stress is offset by this conversion of energy. Moreover, this conversion turns out to dominate any damping by wind during the later stages of eddy lifetime. A scaling analysis of relative wind stress-induced baroclinic conversion and relative wind stress damping also confirms these numerical findings, showing that energy conversion is greater than wind damping. Overall, this highlights the complexities of ocean-atmosphere interactions at the mesoscale, and points to the need for further study in this area.
On the physical nudging equations
Authors: Conti Giovanni , Aydoğdu Ali , Gualdi Silvio , Navarra Antonio , Tribbia Joe
Published: March 2022

In this work we show how it is possible to derive a new set of nudging equations, a tool still used in many data assimilation problems, starting from statistical physics considerations and availing ourselves of stochastic parameterizations that take into account unresolved interactions. The fluctuations used are thought of as Gaussian white noise with zero mean. The derivation is based on the conditioned Langevin dynamics technique. Exploiting the relation between the Fokker–Planck and the Langevin equations, the nudging equations are derived for a maximally observed system that converges towards the observations in finite time. The new nudging term found is the analog of the so called quantum potential of the Bohmian mechanics. In order to make the new nudging equations feasible for practical computations, two approximations are developed and used as bases from which extending this tool to non-perfectly observed systems. By means of a physical framework, in the zero noise limit, all the physical nudging parameters are fixed by the model under study and there is no need to tune other free ad-hoc variables. The limit of zero noise shows that also for the classical nudging equations it is necessary to use dynamical information to correct the typical relaxation term. A comparison of these approximations with a 3DVar scheme, that use a conjugate gradient minimization, is then shown in a series of four twin experiments that exploit low order chaotic models.
Relative contribution of surface water concentrations (pCO2aq) and gas transfer velocity (k) to CO2 flux variability in boreal lakes
Authors: Rudberg David , Schenk Jonathan , Pajala Gustav , Sawakuchi Henrique , Sieczko Anna , Karlsson Jan , MacIntyre Sally , Melack John , Sundgren Ingrid , Bastviken David
Published: March 2022

Lakes emit CO2 to the atmosphere at magnitudes significant for the global carbon cycle, in the form of diffusive CO2 flux (FCO2). As direct FCO2 measurements are time-consuming, FCO2 is often estimated from the air-water CO2 concentration gradient (ΔpCO2) and the gas transfer velocity (k), representing the two components considered to regulate FCO2. However, extrapolating measurements of ΔpCO2 and k to whole-year estimates require understanding of their variability in time and across different types of lakes, which is often insufficient. As a result, simple linear interpolations are typically used in extrapolations which risk producing bias as spatiotemporal variability is not included. Further insight to the variability of ΔpCO2 and k may contribute to more representative extrapolations and provide guidance for focusing sampling campaigns on capturing times of high variability. We used floating flux chambers and surface water samples to measure FCO2 and ΔpCO2, respectively, both within-weeks and over seasons during the open water period at 12 locations in each of 15 boreal lakes across a latitudinal gradient in Sweden. We combined these measurements to derive spatially resolved values of k in order to identify: i) the contributions of ΔpCO2 and k to FCO2 variability over time; and ii) if differences in the contributions of ΔpCO2 and k to FCO2 variability can be related to lake characteristics. The results presented are relevant for improved modelling of lake CO2 emissions.
A Tool for  Accelerometer Modeling
Authors: Reis Arthur , Kupriyanov Alexey , Müller Vitali
Published: March 2022

    Accelerometers are integral part of the science instrument payloads of space based gravimetry and gravitational wave measurements. These are either used to detect the actuating forces on the body of the spacecraft, to enable a drag-free scenario where a test mass will follow a geodesic, or combined in pairs as to build a gradiometer. From a technological standpoint, different techniques have been used to measure the acceleration, from capacitance reading, to optical interferometry, to cold atom interferometry. As the next generation gravimetry missions are considered, there is a need to assist the design of this instrument, preferentially without having to recreate a model for each family of devices within the same framework, in order to simulate its performance and to enable the best science return.
    
    Here is presented a tool to model and simulate accelerometers. This comprises a Simulink library containing the components and their associated Matlab scripts. It is being developed to be modular, parametric, agnostic in respect of measurement technique, flexible in the mode of operation of the instrument, and instantiable to accommodate scenarios with multiple accelerometers on one or more spacecrafts. This tool can run as a standalone simulation, with multiple arbitrary generated noise inputs to obtain the overall noise budget and also can be integrated with XHPS, a Simulink library that simulates satellite dynamics with high precision gravity field models, to calculate the in-flight instrument sensitivity.
InSAR measurements of ground deformations at Ischia island (Naples, Italy) along two decades dataset
Authors: Beccaro Lisa , Tolomei Cristiano , Spinetti Claudia , Bisson Marina , Colini Laura , De Ritis Riccardo , Gianardi Roberto
Published: March 2022

Ground deformation at volcanic areas is mainly driven by the interaction between lithology, morphology, seismology and volcanism. In the latest decades, radar interferometry has contributed to understand the volcanic dynamics through the measurement of ground deformations. This work focuses on the displacement analysis at Ischia, an active volcanic island located at the north-western end of the Gulf of Naples and characterized by a long eruptive and seismic history. The central portion of the island is dominated by Mt. Epomeo, a volcano-tectonic horst formed by caldera resurgence, tilted southward and bordered by a system of faults and fractures which represent the preferred degassing pathway of the hydrothermal system beneath the island. Seismicity is mainly concentrated in the northern area and the most recent and severe seismic sequence started with the Mw 3.9 earthquake on August 21st 2017 producing several damages and also victims. In this study, the investigation of surface displacement was carried out over a continuous time interval of about 17 years by using Synthetic Aperture Radar (SAR) dataset with different temporal and spatial resolutions. The Small Baseline Subset interferometric technique was applied to the dataset allowing the identification of the areas more potentially prone to trigger slope instability phenomena. The resulting ground displacement maps identified the highest deformations along the north-western, western and southern slopes of Mt. Epomeo and were validated by using GPS data acquired by local geodetic network. Mean velocity maps obtained from C-band Envisat and Sentinel-1 and X-band COSMO-SkyMed SAR data will be presented together with the ground deformation effects caused by the 2017 seismic swarm.
Analysis of high-resolution Digital Elevation Model (DEM) of the Afrera Plain (Afar) reveals relationship between magmatism and tectonics in a rift transfer zone
Authors: La Rosa Alessandro , Pagli Carolina , Hurman Gareth , Keir Derek
Published: March 2022

Continental extension at mature rifts systems focuses along spreading segments where dominant magmatic activity, diking and minor faulting assist plate divergence. Such processes make adjacent spreading segments grow but also interact at zones where the spreading is transferred from one segment to another. A great variety of tectonic structures has been observed at transfer zones, encompassing parallel strike-slip faults (bookshelf faulting) or conjugate systems of en-echelon oblique faults. Transfer zones can also become transform plate boundaries once continental breakup occurs. However, the role of magma in influencing the deformation at rift-rift transfer zones is unclear as direct observations are rare. In this study, we address this open question by exploiting high-resolution Pléiades-1 tri-stereo imagery to produce the first 1 m DEM of the Afrera Plain transfer zone, between the Erta Ale and Tat Ali spreading segments in Northern Afar. This dataset has been used to conduct a detailed structural analysis of both tectonic and magmatic features and explore their geometrical and spatial relationships. We observed different trends and kinematics: Dikes opens with an extension oriented ~N65°E, consistent with the regional extension; tectonic features have instead an extensional component with direction varying between ~N46°E and ~N68°E. Riedel shears and measurements of fractures opening directions indicate that tectonic deformation occurs along two families of NW-SE- and NS-striking oblique faults having right-lateral and left-lateral components, respectively. At the same time, spatial relationships between faults and lava flows also indicate that magmatic and tectonic activity co-exist in the transfer zone. We explain these observations by two different strain fields acting in the Afrera Plain during magmatic and amagmatic phases. During magmatic phases, dikes open orthogonal to the spreading direction responding to the regional extension. Conversely, during amagmatic phases, the transfer zone is dominated by the interaction between the two spreading segments with counterclockwise rotations of the strain field and shear motions accommodated by conjugate fault systems.
Weak turbulence and quasilinear diffusion for relativistic wave-particle interactions via a Markov approach
Authors: Allanson Oliver , Elsden Thomas , Watt Clare , Neukirch Thomas
Published: March 2022

We derive weak turbulence and quasilinear models for relativistic charged particle dynamics in pitch-angle and energy space, due to interactions with electromagnetic waves propagating (anti-)parallel to a uniform background magnetic field. We use a Markovian approach that starts from the consideration of single particle motion in a prescribed electromagnetic field. This Markovian approach has a number of benefits, including: 1) the evident self-consistent relationship between a more general weak turbulence theory and the standard resonant diffusion quasilinear theory (as is commonly used in e.g. radiation belt and solar wind modeling); 2) the general nature of the Fokker-Planck equation that can be derived without any prior assumptions regarding its form; 3) the clear dependence of the form of the Fokker-Planck equation and the transport coefficients on given specific timescales.

Of particular interest is the ability to derive the governing Fokker-Planck equation, and the required 1st-order (drift) and 2nd-order (diffusion) transport coefficients. Furthermore this method allows for both the inclusion of non-resonant effects, as well as interactions over very short timescales, below a typical de-correlation timescale. All of these nonlinear features have recently been shown to be important for high-energy electron dynamics, and are beyond the reach of the standard resonant diffusion quasilinear theory.

This concise derivation and discussion of the weak turbulence and quasilinear theories using the Markovian framework is physically very instructive and may form fundamental groundwork for future studies.

Front. Astron. Space Sci. - Research Topic (Plasma Waves in Space Physics: Carrying On the Research Legacies of Peter Gary and Richard Thorne)

doi: 10.3389/fspas.2021.805699 (Reviewed by Danny Summers & Jay M. Albert)
What stable water isotopes may tell us about belowground processes
Authors: Meusburger Katrin , Bernhard Fabian , Gessler Arthur
Published: March 2022

Processes in the rooting zone and root water uptake decisively affect ecosystem resilience to stressors such as drought or deposition of air pollutants. However, the rooting zone is literally a black box. Water stable isotopes may shed light on some parts of this black box and tell us about water residence times, mixing of different water pools, plant water sources, preferential flow, soil evaporation, and many more. While this flexibility to use stable water isotopes is advantageous, it also entails many degrees of freedom. The additional collinearity of the hydrogen and oxygen isotopes leads to a largely underdetermined problem to solve. Bayesian mixing models help quantify the resulting uncertainty and add some constraints to the system by prior knowledge. Particularly in the case of disentangling plant water sources, additional data such as soil water content, matric potential or sap flow are needed since i) the isotope gradient smoothes with soil depth and ii) isotope-derived relative changes in root water uptake cannot be translated to absolute ones. Framing this ancillary data in a physically based water balance model may refine our predictions and help to trace water and related nutrient fluxes through the belowground. This contribution will summarize some of the experience gained during an in-situ monitoring study conducted in the drought summer of 2018 and a one-year sampling campaign at ten long-term ecosystem monitoring sites across Switzerland.
Evidence for clear-sky dimming and brightening in the long-term Potsdam radiation record
Authors: Wild Martin , Wacker Stefan , Yang Su , Sanchez-Lorenzo Arturo
Published: March 2022

For the explanation of the observed decadal variations in surface solar radiation (known as dimming and brightening) the relative importance of clouds and the cloud-free atmosphere (particularly aerosols) is currently disputed. Here we investigate this issue using daily data from the prominent long-term observational radiation record at Potsdam, Germany, over the 71-years period 1947-2017. We identify cloud-free days based on synop cloud observations as well as on days with maximum atmospheric transmission. Irrespective of the cloud-screening method, strong dimming and brightening tendencies in the atmospheric transmission are evident not only under all-sky, but also of similar magnitude under clear-sky conditions, causing multidecadal variations in surface solar radiation on the order of 10 Wm-2. This points to the cloud-free atmosphere as a main responsible for dimming and brightening in Central Europe and suggests that these variations are anthropogenically forced rather than of natural origin, with aerosol pollutants as likely major drivers.

This study has been published in Geophysical Research Letters (Wild et al. 2021)

Reference:

Wild, M., Wacker, S., Yang, S., and Sanchez-Lorenzo, A. (2021). Evidence for clear-sky dimming and brightening in central Europe. Geophysical Research Letters, 48, e2020GL092216. https://doi. org/10.1029/2020GL092216

 

 
Evaluation of the hydraulic exchange in the hyporheic zone: A depth-oriented analysis focusing on upstream and downstream conditions.
Authors: Mahindawansha Amani , Gassmann Matthias
Published: March 2022

The groundwater-surface water interface, which is known as hyporheic zone, is a dynamic system that plays an important role in the hydrological functioning of catchments. During flow exchange, there are many chemical attenuation processes due to the variation of physical and chemical properties including surface water flow and the morphology of the riverbed. The fluctuations may depend on the seasonality, climatic zone, as well as due to the local variations such as soil structure, geology, land use, water sources etc.

The goal of the study was to gain a depth orientated insight into the hyporheic exchange functioning, mainly focusing on the difference between upstream and downstream conditions. We collected water samples from 4 different depths until 0.5 m below the stream bed surface of the stream Ahna in Kassel, Germany, using multi-level interstitial probes. The samples were taken at different locations in the stream during a whole year. Water samples were analyzed for stable isotopes of water (δ2H and δ18O) and some major ions. Results indicate that the variations following the depth, sampling time and the location. Isotopic signatures show the summer enrichment and the winter depletion, mirroring the seasonality of stable isotopes in rainfall. We also observed an isotopic enrichment at the downstream sites and significantly higher ion concentrations, especially for K+, Na+, Mg2+, Cl-, NO3-, than the upstream. Water extraction flow rates decreased along the depth profile due to the changes in effective porosities and the hydraulic conductivities which were controlled by the sediment structure and clogging processes.
The tropical stratospheric upwelling sets the tropical equilibrium climate sensitivity by reducing the effective forcing
Authors: Jiménez de la Cuesta Otero Diego , Schmidt Hauke
Published: March 2022

Several modeling studies identified a climate-chemistry feedback mechanism that modulates the global equilibrium climate sensitivity (ECS) through changes in the tropical upper-tropospheric and lower-stratospheric (UTLS) water vapor. The main factors producing this feedback are the upward shift of the tropical tropopause layer (TTL) and the acceleration of the Brewer-Dobson circulation (BDC). These two processes change the ozone (O3) concentration, resulting in a drier UTLS region than without O3 changes. Thus, the planetary long-wave emissivity increases and the ECS decreases. However, the BDC alone provides a tropical dynamical cooling in the UTLS region. This cooling is modified by the carbon dioxide (CO2) diabatic effects. Thus, the magnitude of the BDC changes can directly impact the tropical, if not the global, ECS. We build upon the work of Dacie et al. (2019), who analyzed how O3 changes affected the tropical ECS and TTL temperature. We study how the changes in the tropical upwelling directly affect the tropical ECS using the forcing-feedback framework. We find that the tropical upwelling changes dampen the effective radiative forcing, thereby reducing the ECS. Adding O3 chemistry shows that the changes in upwelling greatly enhance the climate chemistry-feedback but, more importantly, enhance the dampening of the effective radiative forcing and the reduction in ECS. Nonetheless, we cannot answer if these tropical effects of upwelling affect the global ECS until we include the extratropical regions.
Physics-constrained postprocessing of surface temperature and humidity
Authors: Zanetta Francesco , Nerini Daniele
Published: March 2022

Traditional post-processing methods aim at minimizing forecast error. This often leads to predictions that violate physical principles and disregard dependencies between variables. However, for various impact-based applications such as hydrological forecasting or heat indices, it is important to provide forecasts that not only have high univariate accuracy, but also are physically consistent, in the sense of respecting physical principles and variable dependencies. Achieving physical consistency remains an open problem in the post-processing of weather forecasts, while this question has recently gained a lot of attention in the wider deep learning community and climate field. Recent contributions show that physical consistency may be pursued by applying different forms of constraints to deep learning models. The most widely used approaches are to incorporate physics via regularization, by defining physics-based losses in addition to common metrics such as mean absolute error, or to define custom-designed model architectures, such that the physical constraints are strictly enforced. Including constraints also has the potential to help the training procedure by restraining the hypothesis space of the model and improving generalization capabilities.

This work investigates the application of the aforementioned approaches for the postprocessing of a set of variables related to surface temperature and humidity, specifically temperature, dew point, surface pressure, relative humidity and water vapor mixing ratio. As baseline, we use an unconstrained fully connected neural network. We consider the simple case of postprocessing at a single location, and we show how it is possible to incorporate domain knowledge, specifically thermodynamic relationships, via analytic constraints, to obtain physically consistent postprocessed prediction. We compare different approaches and show that we can enforce physical consistency without degrading performance, or even improving it. Furthermore, we discuss additional advantages and disadvantages of these approaches in the context of post-processing, besides error reduction.