bluuebunny/crossref_metadata_2025 huggingface dataset:
Near-field observations of snow-avalanches propagating over a fiber-optic array
Authors: Paitz Patrick , Edme Pascal , Fichtner Andreas , Lindner Nadja , Sovilla Betty , Walter Fabian
Published: March 2022

We present and evaluate array processing techniques and algorithms for the characterization of snow avalanche signals recorded with Distributed Acoustic Sensing (DAS).

Avalanche observations rely on comprehensive measurements of sudden and rapid snow mass movement that is hard to predict. Conventional avalanche sensors are limited to observations on or above the surface. Recently, seismic sensors have increased in their popularity for avalanche monitoring and characterization due to their avalanche detection and characterization capabilities. To date, however, seismic instrumentation in avalanche terrain is sparse, thereby limiting the spatial resolution significantly.

As an addition to conventional seismic instrumentation, we propose DAS to measure avalanche-induced ground motion. DAS is a technology using backscattered light along a fiber-optic cable to measure strain (-rate) along the fiber with unprecedented spatial and temporal resolution - in our example with 2 m spatial sampling and a sampling rate of 1kHz.

We analyze DAS data recorded during winter 2020/2021 at the Valleé de la Sionne avalanche test site in the Swiss Alps, utilizing an existing 700 m long fiber-optic cable. Our observations include avalanches propagating on top of the buried cable, delivering near-field observations of avalanche-ground interactions. After analyzing the properties of near-field avalanche DAS recordings, we discuss and evaluate algorithms for (1) automatic avalanche detection, (2) avalanche surge propagation speed evaluation and (3) subsurface property estimation.

Our analysis highlights the complexity of near-field DAS data, as well as the suitability of DAS-based monitoring of avalanches and other hazardous granular flows. Moreover, the clear detectability of avalanche signals using existing fiber-optic infrastructure of telecommunication networks opens the opportunity for unrivalled warning capabilities in Alpine environments.
High-throughput phenotyping of 38 maize varieties for the study of rhizosphere traits affecting agronomic resilience under drought stress 
Authors: Tung Shu-Yin , Köhler Tina , Wild Andreas J. , Steiner Franziska , Tyborski Nicolas , Pausch Johanna , Lüders Tillmann , Müller Carsten W. , Vidal Alix , Carminati Andrea , Vahl Wouter , Groth Jennifer , Eder Barbara , Wolfrum Sebastian
Published: March 2022

The occurrence of drought is likely to increase and intensify as a result of climate change, which poses a great challenge to agriculture. It is thus crucial to enhance agronomic resilience to secure food and feed production. Roots and root functioning as well as the interplay of roots with the surrounding soil, the rhizosphere, plays a key role in water acquisition of plants. Investigating rhizosphere traits is hence promising to shed light on future crops that better adapt to drought stress. A great strength of this study is the screening of various varieties which is facilitated by the high-throughput phenotyping method. It allows a wider coverage of traits and especially the genetic and phenetic diversities preserved in landraces.

Maize (Zea mays L.), being one of the major cereal crops worldwide, was selected as the plant of study. A total of 38 varieties, which encompasses hybrid varieties, open pollinated varieties, and landraces, were screened in the “Moving Fields”, a greenhouse equipped with the high-throughput phenotyping facility in the Bavarian State Research Center for Agriculture. Maize plants were grown in mesocosms filled with loamy soil. Plants were exposed to two water treatments, well-watered and drought-stressed, during vegetative stem extension stage. Dynamic plant development was captured by continuous image acquisition. A visible light (RGB) camera was used to document the size and architecture of shoots and roots, while a chlorophyll fluorescence camera recorded the metabolic activity of shoots.

Using shoot images, we compared variety-specific plant growth curves under well-watered and drought-stressed conditions to highlight the growth strategy of plants towards drought stress. The results reveal differences in growth inhibition during drought across varieties. In addition, differences in shoot and root dry weights are found between landraces and modern varieties. More analyses are in progress in search of rhizosphere traits and their influences on agronomic resilience.
Half-precession signals in marine an terrestrial records – connecting IODP/ICDP sites from the equatorial Atlantic to Greenland
Authors: Ulfers Arne , Zeeden Christian , Voigt Silke , Sardar Abadi Mehrdad , Wonik Thomas
Published: March 2022

The characteristics of half-precession (HP) cycles (~9,000 - 12,000 years) is still poorly understood, despite their appearance in numerous records. We analyse HP signals in a variety of different marine and terrestrial proxy records from Europe and the Atlantic Ocean, investigate the temporal evolution of the HP signal from the early/middle Pleistocene to the present, and evaluate the potential of the HP to reflect the connectivity of climate systems over time.

We apply filters on the datasets that remove the classical orbital cycles (eccentricity, obliquity, precession) and high frequency signals, and focus on the bandwidth of HP signals. Wavelet annalysis and correlation techniques are used to study the evolution of specific frequencies through the different records.

In addition to a connection of HP cycles with interglacials, we observe a more pronounced HP signal in the younger part of several proxy records. Besides, we observe a trend of more pronounced HP signals in low latitude records compared to high latitudes. This is in agreement with the assumption that HP is an equatorial signal and can be transmitted northward via various pathways. The appearance of HP signals in mid- and high-latitude records may thus be an indicator for the intensity of the transporting mechanisms. We suggest that the African Monsoon plays a major role in this context, as its magnitude directly influences the climate systems of the Mediterranean and Southern Europe. In order to better understand the African climate variability, both equatorial marine and terrestrial records will be examined with respect to HP.
Does vegetation shift in Arctic tundra upon permafrost degradation influence mineral element recycling in the topsoil?
Authors: Villani Maëlle , Mauclet Elisabeth , Agnan Yannick , Druel Arsène , Jasinski Briana , Taylor Meghan , Schuur Edward A.G. , Opfergelt Sophie
Published: March 2022

Climate change affects the Arctic and Subarctic regions by exposing previously frozen permafrost to thaw, unlocking nutrients, changing hydrological processes, and boosting plant growth. As a result, Arctic tundra is subject to a shrub expansion, called “shrubification” at the expense of sedge species. Depending on intrinsic foliar properties of these plant species, changes in foliar fluxes with shrubification in the context of permafrost degradation may influence topsoil mineral element composition. Despite the potential implications for the fate of organic carbon in the topsoil, this remains poorly quantified. Here, we investigate vegetation foliar and topsoil mineral element composition (mineral elements that influence organic carbon decomposition: Si, K, Ca, P, Mn, Zn, Cu, Mo and V) from a typical Arctic tundra at Eight Mile Lake (Alaska, USA) across a natural gradient of permafrost degradation. Results show that foliar element concentrations are higher (up to 9 times; Si, K, Mo, and for some species Zn) or lower (up to 2 times; Ca, P, Mn, Cu, V, and for some species Zn) in sedge than in shrub species. This induces different foliar flux with permafrost degradation and shrubification. As a result, a vegetation shift over ~40 years from sedges to shrubs has resulted in lower topsoil concentrations in Si, K, Zn and Mo (respectively of 52, 24, 20 and 51%) in poorly degraded permafrost sites compared to highly degraded permafrost sites. For other mineral elements (Ca, P, Mn, Cu and V), the vegetation shift has not induced a marked changed in topsoil concentrations at this stage of permafrost degradation. This observed change in topsoil composition involving beneficial or toxic elements for decomposers is likely to influence organic carbon decomposition. These data can serve as a first estimate to assess the influence of other shifts in vegetation in Arctic tundra such as sedge expansion with wildfires.
Globally Tracking Dust Devil Vortices on Mars Using Neural Networks
Authors: Conway Susan  J. , Bickel Valentin T. , Patel Manish R. , Fenton Lori , Carson Helen
Published: March 2022

Dust devils are atmospheric vortices driven by daytime dry convective circulations and are visible because of the dust entrained from the ground. They are common in deserts on Earth and globally on Mars. They appear as tubular or conical light-coloured clouds of dust that cast a dark shadow which is particularly distinctive in orbital images. They can reach much larger sizes on Mars (several km in height), compared to Earth, perhaps because their size is limited by the depth of planetary boundary layer. Here, we perform a global survey for dust devil vortices by using a neural network to search through the database of Context Camera (CTX) images aboard NASA’s Mars Reconnaissance Orbiter spanning Mars Years 28-35.

We used an off-the-shelf convolutional neural network (CNN) architecture (RetinaNet) as used successfully for previous planetary studies. After training and testing (average precision AP ~0.7) we processed the whole database of CTX images (n=111,547 images) for dust devil detections using the JMARS-served CTX images. Every detection with a CNN confidence level (CT) greater than 0.5 (n=57,051) was verified by a human operator. The effective diameter of the dust devil was estimated from the bounding box size by measuring the diameter of the “cloud” in a sample of 33 dust devils to generate a linear scaling relationship.

3,747 images were found that contained validated dust devils at CT >0.5, comprising 11,201 individual detections. The images spanned MY 28 starting at Ls 114° through to MY 35 at Ls 114°. Trends in frequency and size of dust devils with season agree with previous studies, where higher densities and larger sizes of dust devils are found in local summer for each hemisphere and low levels of activity occur in local winter. Valles Marineris and Elysium Planitia (InSight, MSL) are notable areas lacking dust devils despite good temporal image coverage. We confirm the hotspots of Chryse and Hellas Planitiae noted in some, but not all previous studies. We find two notable hemispherical asymmetries in the data: (a) The peak in size/density occurs just after the solstice in the southern hemisphere, but at the solstice in the northern hemisphere. (b) Excluding known hotspots in Amazonis and Arcadia Planitiae we find that two broad latitudinal zones seem to exhibit both higher frequency and size: 55-70°N at Ls 120-150° and 50-70°S at Ls 300-330°, agreeing with observations of dust devil tracks. We attribute the hemispherical asymmetries to the dominance of the southern summer Hadley circulation and are investigating this further using data from the OpenMARS climate database.

Acknowledgments: we thank the JMars team at ASU for hosting map projected CTX image products used in this work. SJC acknowledges the French Space Agency CNES for supporting her Mars work.
Basal Properties of the Filchner-Ronne Sector of Antarctica from Inverse Modeling and Comparison with Ice-Penetrating Radar Data
Authors: Wolovick Michael , Höyns Lea-Sophie , Kleiner Thomas , Nickel Niklas , Helm Veit , Humbert Angelika
Published: March 2022

Lubrication by subglacial water or saturated subglacial sediments is crucial to controlling the movement of fast-flowing outlet glaciers and ice streams.  However, the subglacial environment is difficult to observe directly.  Here, we combine inverse modeling with ice-penetrating radar observations to characterize the ice sheet bed in the Filchner-Ronne sector of Antarctica, with a specific focus on the Recovery Glacier catchment.  First, we use the Ice Sheet System Model (ISSM; Larour et al., 2012) to assimilate satellite observations of ice sheet surface velocity (Mouginot et al., 2019) in order to solve for basal drag and ice rheology across the Filchner-Ronne sector of Antarctica.  Next, we compare these results with ice-penetrating radar observations sensitive to the presence of ponded water at the ice sheet base (Humbert et al., 2018; Langley et al., 2011), along with remotely sensed observations of active lakes (Smith et al., 2009) and putative large subglacial lakes inferred from the ice sheet surface slope (Bell et al., 2007).  We find that the main fast-flowing region of Recovery Glacier is mostly low-drag, with the exception of localized sticky spots and bands.  The boundary between rugged subglacial highlands and a deep subglacial basin near the onset of the ice stream is associated with a sharp reduction in basal drag, although surface velocity changes smoothly rather than abruptly across this transition.  An upstream shear margin, visible in satellite radar images of the ice surface, is associated with low basal drag.  The putative large lakes have low drag but are not strongly distinguished from their surroundings, and radar evidence for ponded subglacial water within them is weak.  The active lakes identified from satellite altimetry are similarly situated in areas of low basal drag, but have limited radar evidence for ponded subglacial water.  An L-curve analysis indicates that our inverse model results are robust against changes in regularization, yet the radar-identified lake candidates do not have a clear relationship with low-drag areas in the fast-flowing ice stream.  We conclude that the deep-bedded regions of Recovery Glacier are underlain by saturated subglacial sediments, but classic ponded subglacial lakes are much more rare.  Isolated sticky spots and bands within the ice stream are either due to protrusions of bedrock out of the sediments or to localized areas of frozen and/or compacted sediments.
Isotopic characterization of methane: insights from clumped isotope (13CDH3 and CD2H2) measurements
Authors: Sivan Malavika , Röckmann Thomas , Slomp Caroline P. , van der Veen Carina , Popa Maria Elena
Published: March 2022

Atmospheric methane is an important greenhouse gas, and various methods are used to identify and quantify its sources. The measurement of bulk isotopic composition (δ13C and δD) is a widely used characterization technique, but due to the overlap of source signatures, it is often difficult to distinguish between thermogenic, microbial, and other sources. With the advancement of high-resolution mass spectrometry, it is now possible to measure the rare clumped isotopologues of methane 13CDH3 and CD2H2.

This novel method can give additional information to help constrain methane sources and processes. The clumping anomaly is temperature-dependent and can thus be used to calculate the formation or equilibration temperature when methane is in thermodynamic equilibrium. In case of thermodynamic disequilibrium, the clumped signatures can be exploited to identify various kinetic gas formation and fractionation (mixing, diffusion, etc.) processes. 

We have developed a technique to extract pure methane from air and water samples and to measure the clumped isotope signatures (Δ13CDH3 and ΔCD2H2) with high precision and reproducibility, using the Thermo Ultra mass spectrometer. We will present the current capabilities of this setup, and the results of the first sets of samples measured from different natural environments.
Accuracy of proposed corrections to the current precession-nutation models: A first assessment
Authors: Ferrándiz José M. , Belda Santiago , Juárez Miguel Ángel , Baenas Tomás , Modiri Sadegh , Heinkelmann Robert , Escapa Alberto , Schuh Harald
Published: March 2022

Since 2020 a few research groups have reported new estimations of nutation amplitudes or precession parameters, usually presented as corrections to the nutation and precession theories IAU2000 and IAU2006, as well as new empirical models for the free core nutation (FCN). The main effect of those proposed corrections is reducing the unexplained variance of the celestial pole offsets (CPO) time series. The improvement of the accuracy of CPO models was encouraged by Resolution 5 of the 2019 General Assembly of the International Association of Geodesy (IAG), included among the recommendations of the GGOS/IERS Unified Analysis Workshop held that year, and also supported by Resolution B2 of the International Astronomical Union (IAU) in 2021.

The variance reduction attainable by refining the precession offsets and rates and the amplitudes of the forced nutations is noticeably larger than that resulting from the corrections needed for the consistency of the precession and nutation theories (Escapa et al 2018). However, the amount of the improvement depends strongly on the various fitting strategies, the input CPO series and the time periods chosen for benchmarking.

That fact is shown through the accuracy assessment of a selection of correction models proposed by the authors and other teams, either supplemented with FCN models or not, and for a selection of input CPO data and time spans.

 

The work of JMF, AE, and TB was partially supported by Spanish Projects PID2020-119383GB-I00 funded by MCIN/AEI/10.13039/501100011033 and PROMETEO/2021/030 (Generalitat Valenciana); and SB was  supported partially by Generalitat Valenciana (SEJIGENT/2021/001) and the European Union˜NextGenerationEU (ZAMBRANO 21-04) .
Ray theoretical investigations using matching pursuits
Authors: Michel Volker , Schneider Naomi , Sigloch Karin , Totten Eoghan
Published: March 2022

The three-dimensional structure of the Earth's interior shapes its geomagnetic and gravity fields, and can thus be constrained by observing these fields. 3-D Earth structure also causes seismological observables to deviate from those predicted for approximated, spherically symmetrical reference models. Travel time tomography is the inverse problem that uses these observed differences to constrain the 3-D structure of the interior.
On the planetary scale, i.e. in a spherical geometry, this linearized inverse problem has been parameterized with a variety of basis systems, either global (e.g. spherical harmonics) or local (e.g. finite elements). The Geomathematics Group Siegen has developed alternative approximation methods for certain applications from the geosciences: the Inverse Problem Matching Pursuits (IPMPs). These methods combine different basis systems by calculating an approximation in a so-called best basis, which is chosen iteratively from a so-called dictionary, an intentionally overcomplete set of diverse trial functions. In each iteration, the choice of the next best basis element reduces the Tikhonov functional. A particular numerical expertise has been gained for applications on spheres or balls. Hence, the methods were successfully applied to, for instance, the downward continuation of the gravitational potential as well as the MEG-/EEG-problem from medical imaging.
Our aim is to remodel the IPMPs for travel time tomography. This includes developing the data-dependent operator, deciding for specific trial functions and applying the operator to them. We also have to define termination criteria and develop the regularization in theory and practice. We introduce the IPMPs and show results from our remodelling.
Seasonal Characteristic of Auroral Kilometric Radiation in the Radiation Belts
Authors: Li Ping , Xiao Fuliang , Liu Si , Zhang Sai
Published: March 2022

Auroral kilometric radiation (AKR) is one of the strong radio emission phenomenons with kilometer wavelengths, and similar emissions have been detected on other magnetized planets of the solar system. AKR is generated by suprathermal electrons (1-10 keV) injected from the plasma sheet and has been observed at the lower latitude region of the radiation belts from the Van Allen Probes. Here, we analyze the seasonal characteristic of AKR in the region of L = 3-7 and λ = 0◦− 20◦ using observations from 1 December 2012 to 31 November 2018. Statistical results (4,559 events in total) show that AKR emissions occur most frequently in autumn both in the northern and southern hemispheres. The correlation coefficient between the number of AKR events in each season and the Kp (the geomagnetic activity index) index of these events can reach 0.82. These results suggest that AKR emissions in the lower latitude regions depend on the geomagnetic activity.
Analysis of metal entrapment within anthropogenic tufa using synchrotron micro-XRF
Authors: Cumberland Susan , Tierney Kieran , Renshaw Joanna , Geraki Kalotina , MacDonald John
Published: March 2022

The leaching of heavy metals from post-industrial slag and other anthropogenic waste sites is detrimental for human health and the wider environment. Remediation of these sites can be costly and sustainable low carbon solutions are preferably sought. Examining natural analogues which stabilize metals could provide valuable insights into low-cost solutions to the legacy problems of aquatic environments that are impacted by leaching. Calcareous tufa, sometimes known as travertine limestone, forms naturally when calcium-rich groundwater is exchanged with atmospheric CO2 at mid to hyperalkaline pH resulting in a calcite (CaCO3) precipitation. Tufa has also been observed to form at a small number of old industrial sites (e.g. mining, steel works, paper mills) across northern England and Scotland. One site of interest is at Consett, N.E England, UK. Here tufa precipitates in the Howden Burn stream, a tributary of the River Derwent, as it emerges from the slag heaps from old steel work’s. Bulk analysis shows lead, arsenic, vanadium and zinc are present in the Howden Burn up to several 100 ppm.  Analysis of the water downstream of the tufa shows metal concentrations are considerably reduced compared to concentrations upstream. High spatial resolution LA-ICP-MS analysis of the solid tufa sampled reveal metals present within the tufa structure. This leads to the hypothesis that the metals are precipitated together with the tufa during its formation. However, little is known about metal capture processes during tufa formation and the form that these metals are in.  Here we present synchrotron micro X-ray fluorescence (μ-XRF) element maps of the tufa in cross-section that show the distributions of the metal within the laminations of the tufa structure. Understanding and exploitation of artificial tufa for metal capture could have potential as a CO2 positive solution for sustainable in-stream remediation. 
Ion Acceleration at Magnetotail Turbulent Plasma Jet Fronts
Authors: Richard Louis , Khotyaintsev Yuri V. , Graham Daniel B. , Vaivads Andris , Nikoukar Romina , Cohen Ian J. , Turner Drew L. , Fuselier Stephen A. , Russell Christopher T. , Giles Barbara L. , Lindqvist Per-Arne
Published: March 2022

We investigate a series of Earthward bursty bulk flows (BBFs) observed by the Magnetospheric Multiscale (MMS) spacecraft in the Earth’s magnetotail (X ~ -24 Re, Y ~ 7 Re, Z ~ 4 Re). At the leading edges of the BBFs, we observe complex magnetic field structures. In particular, we focus on one which presents a chain of small scale (~0.5 Re) dipolarizations, and another with a large scale (~3.5 Re) dipolarization. Although the two structures have different scales, both of these structures are associated with flux increases of supra-thermal ions (Ki > 100 keV). We investigate the ion acceleration mechanism and its dependence on the mass and charge state. We show that the ions with gyroradii smaller than the scale of the structure are accelerated by the ion bulk flow. We show that whereas in the small-scale structure, ions with gyroradii comparable with the scale of the structure undergo resonance acceleration, the acceleration in the larger-scale structure is more likely due to a spatially limited electric field. In both cases, we discuss the adiabaticity of the acceleration mechanism.
Assessment of crop yield in China simulated by 13 global gridded crop models
Authors: Yin Dezheng , Li Fang , Lu Yaqiong , Zeng Xiaodong , Zhou Yanqing
Published: March 2022

China is the major agricultural producing country in the world and feeds around 20% of the world population. However, few studies have assessed the crop yield in China simulated by current global crop models, which leave large uncertainties for evaluation of crop productions under future climate change. Here, we perform a systematic evaluation of China’s crop yield simulations made by CLM5-crop and 12 models from the Global Gridded Crop Model Intercomparison (GGCMI) phase I. This is done by comparing simulations of maize, rice, wheat, and soybean yield during 1980-2009 with national yield statistics. Our results show that most GGCMI models overestimate China’s maize and soybean yields, but underestimate rice yield, and fail to simulate the upward trends of the yield for the four crop types. CLM5-Crop generally reproduces the country total yields of maize, rice, and wheat well and can capture the observed significant upward trends in those three crops, although fails to reproduce the magnitude of these trends and the significant upward trend in soybean yield. Most models can simulate the interannual variability of maize yield skillfully, while work poorly for other crop types except CGMS-WOFOST and PEPC for rice, pAPSIM and CGMS-WOFOST for wheat and GEPIC for soybean. In addition, most models struggle to simulate the spatial pattern of crop yield.
Geoastronomy: Rocky planets as the Lavosier-Lomonosov Bridge from the non-living to the living world
Authors: Mojzsis Stephen J.
Published: March 2022

Life on Earth emerged at the interface of the planet’s geosphere, hydrosphere and atmosphere. This setting serves as our basis for how biological systems originate on rocky planets. Often overlooked, however, is the fact that a terrestrial-type planet’s chemical nature is ultimately a product of the Galaxy’s long term evolution. Elemental abundances of the major rock-forming elements (e.g. Si, Mg, Fe) can be different for different stars and planets formed at different times in galactic history. These differences mean that we cannot expect small rocky exoplanets to be just like Earth. Furthermore, age of the system dictates starting nuclide inventory from galactic chemical evolution, and past, present and future mantle and crust thermal regimes. A rocky planet’s bulk silicate mantle composition modulates the kind of atmosphere and hydrosphere it possesses. Hence, the ingredients of a rocky planet are as important for its potential to host life as proximity to the so-called habitable zone around a star where liquid water is stable at the surface. To make sense of these variables, a new trans-disciplinary approach is warranted that fuses the disciplines of Geology and Astronomy into what is here termed, Geoastronomy.
Mating of two current circuits – A new type of plasma instability
Authors: Haerendel Gerhard
Published: March 2022

In the context of the onset of substorms, observations had revealed the frequent occurrence of an unidentified trigger process. Inspections of such onsets had led to the discovery that high-beta plasma at the magnetosphere-tail boundary became suddenly unstable when so-called auroral streamers lined up closely with that boundary. The manifestation was the appearance of bead-like auroral structures preceding the auroral breakup and subject to nonlinear growth. Highly resolved video coverage of a few events showed that the fast moving beads moved opposite to the convective motions on either side. This led to the proposal [Haerendel & Frey 2021] that the trigger of the instability was the formation of a new current circuit, by a non-MHD process, in the gap between the two adjacent circuits of the high-beta plasma boundary and the auroral streamer. Observational evidence and a model of the current structure will be presented.
Analysis of pan-tropical GNSS-R observations from CYGNSS satellites for floods detection and mapping 
Authors: Zeiger Pierre , Frappart Frédéric , Darrozes José
Published: March 2022

Global Navigation Satellite System Reflectometry (GNSS-R) is an emerging remote sensing technique for studying land geophysical parameters. The launch of NASA’s Cyclone GNSS (CYGNSS) mission in 2016 provides GNSS-R data in the pan-tropical area with high spatiotemporal resolution. In this study, we analyze the bistatic observations from CYGNSS for a dynamic floods detection. We compute the coherent reflectivity from CYGNSS L1 data and we grid it at a 0.1°, 7 days spatiotemporal resolution. We use a K-means clustering technique to label the CYGNSS pixels based on their time series of reflectivity. Several reflectivity patterns are extracted from the characteristics of each labelled class: low, medium or high values of reflectivity, and constant or variable amplitude throughout the year. Results are compared to static and dynamic inundation maps, elevation from digital elevation models (DEM), and to land cover information to evaluate the potential of CYGNSS observations for mapping flood dynamics at a global scale. Results highlight the influence of the presence of water on the reflected signals recorded by the CYGNSS satellites. First, high reflectivity values are found over permanent water bodies (lakes, large rivers). Then, seasonal floods are identified by a highly variable value of reflectivity throughout the year, with a peak consistent with the maximum extent of inundations. This is clearly identified over some great floodplains in the Orinoco, Amazon and Parana basins, and over irrigated croplands in the Ganges-Brahmaputra, Mekong and Yangtze basins.

While the global link between CYGNSS observations and floods is assessed, we have identified some limitations at the regional scale. First, very dense canopy layers in tropical forests reduce drastically the penetration of GNSS L-band signals, as for other microwave remote sensing data. Thus, floodplains in densely vegetated areas are underestimated using CYGNSS dataset only. Secondly, the reflectivity over bare soils as in the Sahara or in Australia is high, creating sometimes a confusion with water bodies. Soil Moisture is also well captured by CYGNSS observations with a similar seasonality and a lower amplitude of reflectivity when compared to flooded regions. Finally, CYGNSS observations are affected by the elevation. Water bodies at high elevation suffer from a reduced amplitude of the signal, but are still detectable. To overcome these limitations, a CYGNSS-based mapping of floods dynamics should integrate additional information from the biomass, the land cover and the elevation. We are currently working on this aspect to supply a 0.1°, 7 days CYGNSS flood product to the hydrological community.
Kilns of the Earth: Glass art collaborations to further understanding in volcanology
Authors: Jackson Lucy , Wadsworth Fabian , Mitchell Joanne
Published: March 2022

The material behaviours that underpin artistic work with glass have striking similarities to those of volcanic glasses, silicate melts, and magmas. This similarity presents a compelling opportunity for collaboration between glass artists and volcanologists to better understand silicate melts, and thereby to elucidate volcanic processes.

 

Using silicate melts as an experimental material is advantageous, because it allows us to investigate coupled thermorheological effects that are not well captured by the more widely used low-temperature magma analogue materials such as syrups and oils. Here we present work focussed on adapting and refining the artistic, kiln-based process of bubble entrapment and the precision manipulation of gas phases in glass. These techniques have previously been used to create glass art pieces involving complex bespoke figures formed from gas trapped within layers of glass. We expand the use of this technique to investigate bubble rise dynamics in soda-lime-silicate glass under non-isothermal conditions; varying temperature to slow or accelerate the bubble rise.

We present a scaled mathematical model that provides an excellent description of the experimental data even in case of complex changing temperature environments similar to the long, slow annealing stages of glass art production. Scaling analysis is used to show how our experiments using artistic soda-lime-silica glass can be scaled to volcanic environments. This allows a better understanding of bubble motion in magmas under variable temperature conditions, such as those in shallow basaltic lava lakes, flows, or the uppermost parts of magma plumbing systems.

 

This art-science collaboration used artistic skills and knowledge to validated our model, and tested the limits of the artistic technique: the use of kiln-based heating programs and the glass used by artists. Overall, the advantages of using kiln-based art techniques and skills for volcanology is clear. But we also find that there is a deep mutuality to glass art collaborations, such that the art techniques can be refined via the scientific model development. Ultimately, when working to better understand the behaviours of a complex material such as glass, the approaches of the artist and the scientist are very similar, and our project shows that the presumed disciplinary divide may be less divisive than expected.
Which picker fits my data? A quantitative evaluation of deep learning based seismic pickers
Authors: Münchmeyer Jannes , Woollam Jack , Rietbrock Andreas , Tilmann Frederik , Lange Dietrich , Bornstein Thomas , Diehl Tobias , Giunchi Carlo , Haslinger Florian , Jozinović Dario , Michelini Alberto , Saul Joachim , Soto Hugo
Published: March 2022

Seismic event detection and phase picking are the base of many seismological workflows. In recent years, several publications demonstrated that deep learning approaches significantly outperform classical approaches, achieving human-like performance under certain circumstances. However, as studies differ in the datasets and evaluation tasks, it is yet unclear how the different approaches compare to each other. Furthermore, there are no systematic studies about model performance in cross-domain scenarios, i.e., when applied to data with different characteristics.

Here, we present the results from a large-scale benchmark to address these questions. We compare six previously published deep learning models on eight datasets covering local to teleseismic distances and on three tasks: event detection, phase identification and onset time picking. Furthermore, we compare the results to a classical Baer-Kradolfer picker.

Overall, we observe the best performance for EQTransformer, GPD and PhaseNet, with a small advantage for EQTransformer on teleseismic data. Furthermore, we conduct a cross-domain study, analyzing model performance on datasets they were not trained on. We show that trained models can be transferred between regions with only mild performance degradation, but models trained on regional data do not transfer well to teleseismic data.

As deep learning for detection and picking is a rapidly evolving field, we ensured extensibility of our benchmark by building our code on standardized frameworks and making it openly accessible. This allows model developers to easily evaluate new models or performance on new datasets. Furthermore, we make all trained models available through the SeisBench framework, giving end-users an easy way to apply these models.

 

Published as Münchmeyer, J., Woollam, J., Tilmann, F., Rietbrock, A., Lange, D., Bornstein, T., Diehl, T., Giunchi, C., Haslinger, F., Jozinović, D., Michelini, A., Saul, J. & Soto, H. (2021). Which picker fits my data? A quantitative evaluation of deep learning based seismic pickers. Journal of Geophysical Research: Solid Earth. doi.org/10.1029/2021JB023499
200 million year stratigraphic time-shift on the Moon 
Authors: Werner Stephanie C. , Bultel Benjamin , Rolf Tobias
Published: March 2022

Global scale temporal assignments for planetary surfaces are made based on craters statistics. Age assignments require a cratering chronology model that links normalized crater frequencies and sample ages. A challenge is that rocks on planetary surface may not belong to the site from which they are collected. We use detailed spectral mapping, cratering statistics and impact basin ejecta column estimates to suggest stratigraphic relationships for lunar sampling sites, and most specifically the Apollo 14 landing site. We confirm previously recognised resurfacing in the crater size-frequency distribution in agreement with a single blanketing layer. Based on our and previously published crater statistics, and mineral relation derived from spectral data, we suggest a cratering chronology model that effectively increase the surface age of the Moon. In this presentation, we will document and outline our reasons and data. This change in cratering chronology model implies significant changes for the early solar system evolution time-scale assessment, small body flux and geological dates and rates on all planetary surface when crater statistics is used to determine ages.
Influence of climate change on water balance of the lowlands of southeastern Peru
Authors: González-Rojí Santos J. , Messmer Martina , Raible Christoph C. , Stocker Thomas F.
Published: March 2022

The rainforest of the Amazon basin is considered a biodiversity hotspot, and particularly the low-lying rainforest in southeastern Peru in the department of Madre de Dios. This is obtained by the combination of several different climatic zones and by the heterogeneous weather, related to the transition from the complex topography of the Andes to the rainforest in the lowlands. This ecosystem provides the necessary food and raw materials needed by the local communities. Hence, it is important to understand how the regional to local climate, and particularly, precipitation amounts and patterns will change under global warming. To investigate this, the Weather Research and Forecasting (WRF) model version 3.8.1 is employed to downscale 30-year periods for both present and future climates, obtained by the Community Earth System Model (CESM). The years 1981–2010 are downscaled for the present, while the years 2071–2100 are selected for the future simulation under the high-emission scenario RCP8.5.

Our climate simulation shows that precipitation in Madre de Dios will reduce by around 50-100 mm per month during the wetter months October to March. This reduction accounts for around 30 % of the monthly accumulated precipitation of these months. In April to September, the driest months, a decrease of around 20-50 mm is projected. Especially the decline in precipitation in the driest months has important implications since it could mean that precipitation is completely absent for some of the months. In contrast, along the western slopes of the Andes precipitation is projected to increase during the rainy season by around 75-150 mm per month, whereas drying trends are projected for the remaining months. The projected reductions in precipitation over the rainforest in Madre de Dios influence also temperature, causing more extreme values due to stronger heating effects. The climate simulation projects an increase of 2-3 °C during the rainy season, and 3-4 °C during the dry season. The variability of temperature is also larger in the future compared to the present over Madre de Dios.

The combination of a decrease in humidity and an increase in temperature will exacerbate the risk of fire in the region. To evaluate this risk, the fire weather index (FWI) is calculated, which classifies fire danger into six categories from “very low” to “extreme”. The FWI is “very high” occasionally from July to September in the present, while in the future this level is already reached in June. In both climatic periods the month with the largest fire risk is August, but in the future the risk is increased from “very high” to “extreme”. This confirms the threat of burning large areas unintendedly, particularly during the transformation of rainforest into agricultural land.
Reconstruction of land degradation associated with recent agricultural expansion in Uruguay (1982-2019) based on sediment cores analyses 
Authors: Foucher Anthony , Tassano Marcos , Chalar Guillermo , Cabrera Mirel , Gonzalez Joan , Lefèvre Irène , Evrard Olivier
Published: March 2022

Recent agriculture expansion and land cover conversion (post-1985) induced major deleterious environmental effects in South-America in general and in Uruguay in particular, affecting locally the sustainability of soil and water resources. Whilst the environmental consequences of agriculture’s development were largely studied (e.g. monitoring, modeling) in Europe or North America, much less attention was devoted to the intensity of land degradation in South-America and more specifically, on the Pampa Biome. In this study, sediment cores collected in two reservoirs installed along the Rio Negro river (catchments of 23.000 and 39.000 km²) and draining agricultural catchments were used for reconstructing the evolution of sediment dynamics and source contributions in this region during the last several decades. Various chemical and physical analyses were performed for characterizing this accumulated sediment (e.g. fallout radionuclides, organic matter properties (TOC, δ15N, δ13C, C:N), X-ray fluorescence). Results indicate the significant acceleration of sediment accumulation rates (e.g. by 67% on average in the Rincon del Bonete dam between 2003 and 2019) associated with major phases of agricultural expansion (e.g. expansion of soybean and afforestation). Sediment properties show an increase of native vegetation source contributions associated with the conversion of native grassland into cropland. Understanding the causes of past and present acceleration of sediment delivery are of prime importance in order to protect the soil and water resources with the design of adapted management schemes at the catchment scale.
Mitigation measures for improvement of agricultural drainage water and surface water quality in Denmark
Authors: Hoffmann Carl , Zak Dominik , Kronvang Brian , Carstensen Mette , Audet Joachim
Published: March 2022

Nutrient losses from agricultural areas constitute a major cause for the degradation of aquatic ecosystems worldwide. Sixty percent of the area in Denmark is arable land and thus there is a huge need for mitigation measures to decrease the transport of nutrients from agricultural areas to downstream recipients. We discuss results, experiences and challenges for an optimised implementation of nutrient transport mitigation measures targeting agricultural nutrient losses to fresh and marine water. In 2016 the Agricultural Package was adopted by the Danish Parliament and Danish farmers were again allowed to fertilise their crops to economic optimum. To compensate for the consequent increase in fertilisation rates and the potential negative consequences on water quality, a new nitrogen (N) and phosphorus (P) management plan was introduced. This plan consists of measures to mitigate N losses in smaller catchments (≈ 15 km2) and knowledge of the N-retention capacity of the individual catchments is used for optimisation of the implementation of mitigation measures. A series of nutrient transport mitigation measures has been scientifically approved for use in this new regulation, and more measures are currently undergoing scientific testing. This study focuses on documenting the nutrient retention effects of already approved nutrient transport mitigation measures, such as restoration of riparian wetlands, lowland fens and swamps, re-establishment of shallow lakes, constructed wetlands (surface flow and subsurface flow), as well as measures not yet approved and still under development such as integrated buffer zones, saturated buffer zones and controlled drainage.
Scale-dependent coherence of terrestrial species richness, topography, temperature and precipitation
Authors: Roberts Gareth G. , O'Malley Conor
Published: March 2022

Understanding origins of biodiversity likely requires explanation of how species richness and environment co-vary across the scales of interest, here 10-10,000 km (e.g. river reaches to latitudinal diversity gradients). We focus on quantifying scale and location dependent coherence between terrestrial vertebrate species (carnivorans, bats, songbirds, hummingbirds, amphibians) and topography, mean annual temperature, temperature range, and precipitation. We test the following three hypotheses by developing and applying wavelet spectral techniques. First, as in most geophysical systems, processes operating at long length scales generate most of the topographic and biotic signals observed. Second, scaling regimes can be identified from topographic and biological spatial series, e.g. transects through topographic or species richness, and they indicate that distinct physical regimes govern biodiversity at different scales. Finally, similarities and dissimilarities exist between topographic or biotic spatial series and environmental variables at a range of locations and scales. We examined latitudinal transects through the Americas, Africa, Australia, Asia and global averages. Species richness is shown to be highly coherent and anti-phase with elevation and temperature range, and in-phase with mean annual precipitation and temperature, at scales >1000 km. Coherence between carnivorans and temperature range is low across all scales, which suggest that their richness is insensitive to daily or seasonal changes in temperature. Amphibians, meanwhile, are highly correlated with temperature range at large scales. At scales <1000 km, all species examined, bar carnivorans, show highest richness in the tropics. Terrestrial plateaux are foci of high coherence between carnivorans and elevation at scales centred on 1000 km, which is consistent with the idea that tectonic processes can contribute to biodiversity. The results obtained by spectral analyses of terrestrial species richness and environmental variables highlight the scale-dependent sensitivities of mammals, birds and amphibians to global and local environmental changes.