bluuebunny/crossref_metadata_2025 huggingface dataset:
VOILA on LUVMI-X: A LIBS Instrument for the Detection of Volatiles at the Lunar South Pole
Authors: Vogt David , Schröder Susanne , Hübers Heinz-Wilhelm , Richter Lutz , Deiml Michael , Wessels Peter , Neumann Jörg
Published: March 2021

The lunar south pole is of great interest for upcoming lunar exploration endeavors due to the detection of large reservoirs of water ice in the pole’s permanently shadowed regions [1], which could be utilized to reduce the costs of a sustained presence on the Moon [2]. A strong focus of future robotic exploration missions will therefore be on the detection of water and related volatiles. For this purpose, the project Lunar Volatiles Mobile Instrumentation – Extended (LUVMI-X) is developing an initial system design as well as payload and mobility breadboards for a small, lightweight rover [3]. One of the proposed payloads is the Volatiles Identification by Laser Analysis instrument (VOILA), which uses laser-induced breakdown spectroscopy (LIBS) to analyze the elemental composition of the lunar surface with an emphasis on the detection of hydrogen for the inference of the presence of water. VOILA is a joint project by OHB System AG, Laser Zentrum Hannover e.V., and the German Aerospace Center’s Institute of Optical Sensor Systems. It is designed to analyze targets on the lunar surface in front of the LUVMI-X rover at a variable focus between 300 mm to 500 mm, allowing for precise measurements under various measurement conditions. The spectrometer covers the wavelength range from 350 nm to 790 nm, which includes the hydrogen line at 656.3 nm as well as spectral lines of most major rock-forming elements. The breadboard laboratory setup for VOILA was recently completed and first measurements of Moon-relevant samples have been made. Here, we will show the results of these measurements and will discuss their meaning for the further improvement of the instrument design and for its potential use as a volatile-scouting instrument at the lunar south pole.

[1] Li S. et al. (2018) PNAS, 36, 8907–8912. [2] Anand M. et al. (2012) Planet. Space Sci., 74, 42–48. [3] Gancet J. et al. (2019) ASTRA 2019. [4] Knight A. K. et al. (2000) Appl. Spectrosc., 54, 331–340. [5] Maurice S. et al. (2012) Space Sci. Rev., 170, 95–166. [6] Wiens R. C. et al. (2012) Space Sci. Rev., 170, 167–227. [7] Wiens R. C. et al. (2017) Spectroscopy, 32. [8] Ren X. et al. (2018) EPSC 2018, Abstract EPSC2018-759. [9] Laxmiprasad A. S. et al. (2013) Adv. Space Res., 52, 332–341. [10] Lasue J. et al. (2012) J. Geophys. Res., 117, E1.
Surface manifestations of short-period internal waves of the Kuril-Kamchatka region and the Bering Sea according to satellite observations
Authors: Svergun Egor , Zimin Alexey
Published: March 2021

In the Bering Sea, as in the Kuril-Kamchatka region, which includes the waters near the Kuril Islands and the Pacific waters of the Kamchatka Peninsula, previously performed satellite radar observations show numerous scattered surface manifestations of short-period internal waves (SIW’s). However, the summative study of the characteristics of surface manifestations of SIW’s are currently not available in this region.

In this study, radar images from the Sentinel-1A and B satellites from July 1, 2019 to September 30, 2019 were used to record the surface manifestations of SIW’s. For each surface manifestation of SIW’s, such characteristics as the position of the manifestation, the wavelength, the arc length of the leading ridge in the packet, the direction of propagation, and the number of waves in the packet are determined. Wave detection on the radar images is performed using ESA SNAP and Matlab software.

In the study region, 1,540 SIW’s. manifestations with a wavelength of 80 to 1,900 meters and a leading crest length of 1 to 70 km were registered on 772 radar images. The ranges of variability of the main geometric characteristics of the manifestations in the Kuril-Kamchatka region and in the Bering Sea are very similar. The maximum number of manifestations in the Kuril-Kamchatka region was recorded in the first half of September, and in the Bering Sea – in the second half of July. This difference seems to be related to regional features of pycnocline formation.

Manifestations of internal waves are mainly recorded in the shelf zone. The constant occurrence of manifestations of internal waves located in the southern part of the Kuril Islands, around the Pacific coast of the Kamchatka Peninsula, East of the Litke Strait, and the Straits of the Aleutian chain. It was found that the areas of constant occurrence of the manifestations of SIW’s coincide with the areas of intense dissipation of the internal tide. In the Kuril-Kamchatka region, in contrast to the Bering Sea, manifestations of internal waves are recorded over significant depths at a great distance from the shelf zone, which is associated with the collapse of the internal tide reflected from the edge of the continental slope.

The information obtained in this study will allow us to improve our understanding of the field of short-period internal waves of the north-eastern Pacific Ocean.

The study of surface manifestations of internal waves in the Kuril-Kamchatka region was supported by RFBR grant No. 20-35-90054. The study of surface manifestations of internal waves in the Bering Sea was supported by RFBR grant No. 18-35-20078.
The dynamics of Holocene monsoon based on meteoric 10Be at Kunlun Pass on the northeastern Qinghai-Tibet Plateau
Authors: Chen Peng , Yu Zhongbo , Czymzik Markus , Aldahan Ala , Wang Jinguo , Yi Peng , Possnert Göran , Chen Xuegao , Zheng Minjie , Jin Huijun , Luo Dongliang , Wu Qingbai
Published: March 2021

Multiple proxy records have been used for the understanding of environmental and climate changes during the Holocene. For the first time, we here measure meteoric 10Be isotope of sediments from a drill core collected at the Kunlun Pass (KP) on the northeastern Qinghai-Tibet Plateau (NETP) to investigate mositure and atmospheric circulation changes during the Holocene. The 10Be flux suggests relative low levels in the Early Holocene, followed by a sharp increase to high values at around 4 ka BP (4 ka BP = 4000 years before present). Afterwards, the 10Be flux remains on a high level during the Late Holocene, but decreases slightly towards today. These 10Be deposition patterns are compared to moisture changes in regions dominated by the Indian Summer Monsoon (ISM), East Asian Summer Monsoon (EASM), and the Westerlies. Different from the gradual changes in monsoon patterns, the 10Be data reveal low levels during the Early Holocene until ~4 ka BP when an obvious increase was indicated and a relative high level continues to this day, which is relatively more in agreement with patterns of the Westerlies. This finding provides a new evidence for a shift in the dominant pattern of atmospheric circulation at the KP region from a more monsoonal one to one dominated by the Westerlies. Our results improve the understanding of non-stationary interactions and spatial relevance of the EASM, the ISM and the Westerlies on the Qinghai-Tibet Plateau.
From steady streaming to oscillations: the role of subglacial drainage and temperate ice in ice-stream dynamics
Authors: Haseloff Marianne , Hewitt Ian , Katz Richard
Published: March 2021

The majority of Antarctic ice is discharged through fast-flowing ice streams. Some of these ice streams exhibit variations in velocities and ice stream discharge on decadal to centennial time scales, but the factors controlling these variations are still insufficiently understood.  Using computational models of ice flow and hydrology, we predict the existence of two dynamical regimes: stable ice streaming associated with high hydraulic permeability of the bed, and ‘binge-purge’ oscillations associated with low permeability.

Observations indicate that the fast-flow of ice streams is enabled by meltwater lubricating the ice stream bed, and models suggest that this lubrication is the result of a positive feedback between fast flow, heat dissipation at the ice stream bed and meltwater production within the ice. In particular, recent studies have highlighted that heat dissipation in temperate ice stream margins, which are regions of high lateral strain, can contribute significantly to the subglacial water balance. However, the role of this meltwater flux in ice stream dynamics remains unclear. Here, we investigate the roles of subglacial drainage and feedbacks between fast flow and heat dissipation in ice-stream evolution. 

The ice is modelled as a vertically uniform plug flow. Water flow at the bed is modelled as a Darcian system whose hydraulic transmissivity increases with decreasing effective pressure. Dynamical feedbacks in the energy balance include both frictional heating along the bed and lateral shear heating. Within our model, two distinct dynamic regimes can be identified: if the hydraulic permeability of the bed is sufficiently high to evacuate all meltwater produced at the ice stream bed and in its margins, a moderately-fast steady ice stream forms. Conversely,`binge-purge’ oscillations between fast and stagnant flow emerge when the hydraulic permeability of the bed is too low to evacuate the meltwater produced within the ice stream. Topographic controls can suppress this oscillatory behaviour, while the formation of temperate ice in ice stream margins amplifies it.
Carbon storage in soils and plant biomass under future climate and land use pressures
Authors: Yumashev Dmitry , Janes-Bassett Victoria , Redhead John , Rowe Ed , Davies Jessica
Published: March 2021

It is widely accepted in the scientific, business and policy communities that meeting the Paris Agreement targets will require a large-scale deployment of negative emission technologies and practices. As a result, nature-based climate solutions, including carbon sequestration (Cseq) in soils and forests, have received much attention in the literature recently. Several national and global assessments have identified considerable potential for terrestrial Cseq, while other studies have raised doubts regarding its practical limits in the face of the likely future pressures from climate change and land use change. In general, the existing Cseq assessments lack sensitivity to climate change, perspective on local land use and nutrient limitations. Accounting for these factors requires process-based modelling, and is feasible only at national to regional scales at present, underpinned by a wide body of local evidence. Here, we apply an integrated terrestrial C-N-P cycle model (N14CP) with representative ranges of high-resolution climate and land use scenarios to estimate Cseq potential in temperate regions, using the UK as a national-scale example. Meeting realistic UK targets for grassland restoration and forestation over the next 30 years is estimated to sequester an additional 120 TgC by 2100 (similar to current annual UK greenhouse gas emissions), conditional on climate change of <2°C. Conversely, UK arable expansion would reduce Cseq by a similar magnitude, while alternative arable management practices such as extensive rotations with grass leys would have a comparatively small effect on country-wide Cseq outcomes. Most importantly, the simulations suggest that warmer climates will cause net reductions in Cseq as soil carbon losses exceed gains from increased plant productivity. Our analysis concludes that concerted land use change can make a moderate contribution to Cseq, but this is dependent on us cutting emissions from fossil fuels, soil degradation and deforestation in line with a <2°C pathway.
The experimental geoid 2020 – the first joint geoid model for the North American and Pacific Geopotential Datum 
Authors: Wang Yan Ming , Li Xiaopeng , Ahlgren Kevin , Krcmaric Jordan , Hardy Ryan , Veronneau Marc , Huang Jianliang , Avalos David
Published: March 2021

For the upcoming North American-Pacific Geopotential Datum of 2022, the National Geodetic Survey (NGS), the Canadian Geodetic Survey (CGS) and the National Institute of Statistics and Geography of Mexico (INEGI) computed the first joint experimental gravimetric geoid model (xGEOID) on 1’x1’ grids that covers a region bordered by latitude 0 to 85 degree, longitude 180 to 350 degree east. xGEOID20 models are computed using terrestrial gravity data, the latest satellite gravity model GOCO06S, altimetric gravity data DTU15, and an additional nine airborne gravity blocks of the GRAV-D project, for a total of 63 blocks. In addition, a digital elevation model in a 3” grid was produced by combining MERIT, TanDEM-X, and USGS-NED and used for the topographic/gravimetric reductions. The geoid models computed from the height anomalies (NGS) and from the Helmert-Stokes scheme (CGS) were combined using two different weighting schemes, then evaluated against the independent GPS/leveling data sets. The models perform in a very similar way, and the geoid comparisons with the most accurate Geoid Slope Validation Surveys (GSVS) from 2011, 2014 and 2017 indicate that the relative geoid accuracy could be around 1-2 cm baseline lengths up to 300 km for these GSVS lines in the United States. The xGEOID20 A/B models were selected from the combined models based on the validation results. The geoid accuracies were also estimated using the forward modeling.
Geodynamics of the Central Mediterranean (GEOMED) inferred from ambient seismic noise
Authors: Agius Matthew , Magrini Fabrizio , Diaferia Giovanni , Cammarano Fabio , Faccenna Claudio , Funiciello Francesca , Kästle Emanuel , van der Meijde Mark
Published: March 2021

The Central Mediterranean, the area encompassing Italy, Sardinia, Tunisia and Libya, is characterised by multiple tectonic processes (plate convergence, subduction, and backarc extension). The evolution and interaction of the plate margins within this relatively small area are still being unravelled particularly at the adjacent region known as the Sicily Channel located between Sicily, Tunisia, Libya and Malta. This Channel is characterised by a seismically and volcanically active rift zone. Much of the observations we have today for the southern parts of the Calabrian arc are either limited to the surface and the upper crust, or are broader and deeper from regional seismic tomography, missing important details about the lithospheric structure and dynamics. The project GEOMED (https://geomed-msca.eu) addresses this issue by processing all the seismic data available in the region in order to understand better the geodynamics of the Central Mediterranean.

We measure Rayleigh- and Love-wave phase velocities from ambient seismic noise recordings to infer the structures of the Central Mediterranean, from the Central Apennines to the African foreland, with a special focus on the Sicily Channel Rift Zone (SCRZ). The phase-velocity dispersion curves have periods ranging from 5 to 100 seconds and sample through the entire lithosphere. We invert the dispersion data for isotropic and polarised shear velocities with depth and infer crustal thickness and patterns of radial anisotropy. We find that continental blocks have thick crust (30-50 km), whereas beneath the SCRZ the crust is thin (<25 km), and thinner beneath the Tyrrhenian Sea. Beneath the SCRZ and the Tyrrhenian Sea, the crustal shear velocities are characterised by positive radial anisotropy (VSH>VSV) indicative of horizontal flow or extension, whereas the uppermost mantle is characterised by slow shear velocities indicative of warmer temperatures and strong negative radial anisotropy (VSH>VSV) indicative of vertical flow. We discuss the relevance of these findings together with other geophysical studies such as the regional seismicity and GPS velocity vectors to identify the rifting process type of the SCRZ.

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 843696.
Crustal Thickness Variation Across the Sea of Marmara Region, NW Turkey: A Reflection of Modern and Ancient Tectonic Processes
Authors: Jenkins Jennifer , Stephenson Simon , Martinez-Garzon Patricia , Bohnhoff Marco , Nurlu Murat
Published: March 2021

The Marmara region in Turkey is an important geological setting, both from a tectonic and a seismic hazard/risk perspective. Here we present a recently published map of crustal thickness variation across this complex region (Jenkins et al., 2020), to aid in furthering our understanding of the past and present tectonic processes that formed present‐day structure. The crustal thickness map was created using Ps converted phases and receiver function (RF) analysis of earthquakes recorded at all publicly available seismic stations and stations in the national monitoring network (run by AFAD Disaster and Emergency Management Authority Turkey). RFs were converted from time to depth using a local 3‐D full‐waveform tomographic model and combined in multiphase common conversion point stacks, such that direct P to S converted arrivals and associated multiples are used together to produce continuous maps of the Moho discontinuity. Results reveal the Moho beneath Marmara ranges in depth from 26–41 km, and shows a regional trend of westward thinning, reflecting the effects of the extensional regime in western Anatolia and the neighboring Aegean Sea. The thinnest crust is observed beneath the western end of the Sea of Marmara, and can be attributed to transtensional basin opening. A distinct region of increased crustal thickness bounded by the West Black Sea Fault in the west, and the northern strand of the North Anatolian Fault in the south, defines the ancient crustal terrane of the Istanbul Zone. Isostatic arguments indicate that the thickened crust and lower elevation in the Istanbul Zone require it to be underlain by thicker lithosphere, a conclusion that is consistent with its hypothesized origin near the Odessa shelf.
The influence of soil moisture conditions on the spatio-temporal variability of event rainfall-runoff coefficients in UK catchments
Authors: Zheng Yanchen , Woods Ross , Li Jianzhu , Feng Ping
Published: March 2021

Since the bias and uncertainties of the current design flood estimation methods for ungauged catchments are inevitable, estimation of the design flood in ungauged catchments still remains an unsolved problem. The derived distribution approach appears to be the one of the promising design flood estimation methods, as this method can improve the understanding on which processes contribute most to flood in ungauged catchments. Generally, the distribution of rainfall characteristics and lumped rainfall-runoff modelling was incorporated to estimate the flood magnitude in this method. However, we should note that rainfall is not the only driving factor of flood events. Soil moisture conditions are also an important driving factor affecting the rainfall-runoff transformation, and may even control rainfall-runoff coefficients to a higher degree than does rainfall. Hence, here we perform soil moisture analysis at national scale by employing GLDAS-Noah datasets, and link this to observed event runoff coefficients from a large sample of UK catchments. The relationship between soil moisture conditions and rainfall-runoff coefficient was explored to analyse the spatio-temporal variability of runoff coefficient. This study laid the foundation for further development of a practical derived distribution method, by considering the statistical distribution of rainfall-runoff coefficients and the influence of soil moisture conditions.
Safety evaluation of buildings under flood impact
Authors: Rong Youtong , Bates Paul , Neal Jeffrey
Published: March 2021

The flood caused by a dam-break event generally contains a large amount of energy, and it can be destructive to the downstream buildings and structures. An experiment-validated three-dimensional numerical model was designed to investigate the impact of dam-break flood on structures with different arrangements. The Eulerian two-phase flow model and the smooth particle dynamics method are applied separately to solve the flow motion, and  the deformation characteristics of buildings under the flood impact are evaluated by fluid-structure interaction model. An experiment is constructed to validate the numerical simulation. The results show that the structure suffers a large instantaneous impact pressure when the flood water first contacts the structure, and the value of this pressure can reach 1.5-3.0 times that of the maximum pressure after the first impact, and the maximum total pressure of the upstream building surface is about 1800N. The deformation near the door and windows is obvious, and the maximum deformation can reach 600μm, which further results in the large deformation of the gable and roof on both sides. Moreover, the arrangement of buildings has different blocking effect on flood. The back-row buildings arranged in alignment along the flow direction still has to bear 20% flood impact, and the front row buildings arranged alternately bear 90% high-speed flow impact. The structural damage is evaluated by the material failure criterion, and the weak position of buildings is identified, providing an optimal design of buildings.
Mountain agro-ecosystems long-term trajectories in the North Western Alps
Authors: Giguet-Covex Charline , Bajard Manon , Chen Wentao , Walsh Kevin James , Rey Pierre-Jérôme , Messager Erwan , Etienne David , Sabatier Pierre , Ficetola Francesco Gentile , Gielly Ludovic , Blanchet Claire , Guffond Christophe , Arnaud Fabien , Poulenard Jérôme
Published: March 2021

Past trajectories of alpine agro-ecosystems are legacies that we should consider in the context of current global changes. By integrating archaeology, history and multi-proxy palaeoenvironmental records including lake sediment DNA, we reconstructed the precise nature of agro-pastoral activities and their interactions with the landscape evolution (erosion and vegetation) in the Northwestern Alps, across an altitudinal gradient ranging from 880 and 2440 m a.s.l. We demonstrate that the origins of current vegetation cover in the “Alpages” date to the Mid to Late Bronze Age. However, at the lower limit of the subalpine belt and below this zone, the first significant plant cover changes date to a later period, from the Early to High Middle Ages. From the Bronze Age, we see also anthropogenic disturbances of the natural erosion cycle, especially on some sites in the subalpine belt. This erosion became generalized across all sites during the Roman period. Then, decreasing anthropogenic impacts on the erosion are recorded everywhere, which suggests the beginning of efficient soil management strategies, with protection of the soil resource. This important tipping point arose from the High to Late Middle Ages, when activities and practices are changing.
Local Seismic site effects estimated by detailed seismic surveys: the case of Castelnuovo village (L’Aquila Basin, central Italy)
Authors: Spadi Marco , Tallini Marco , Albano Matteo , Cosentino Domenico , Nocentini Marco , Saroli Michele
Published: March 2021

Assessing seismic site effects is essential in earthquake hazard studies. Local seismic amplification is strongly related to the site stratigraphy and topography, the dynamic properties of the subsoil deposits, and the earthquake features. The evaluation of these factors is mandatory to achieve a consistent model of the seismic hazard at small scale. Here we discuss the case of Castelnuovo village (L’Aquila, central Italy). Located on a small ridge, approximately 60 m higher than the valley floor, the village was heavily struck by April 6, 2009, Mw 6.3 L’Aquila earthquake, with catastrophic collapse of several buildings. Previous studies ascribed the observed damage to the presence of shallow caves beneath the buildings or to the topographic amplification.

In this work, an updated and detailed subsoil model for Castelnuovo site has been provided, based updated geological surveys, such as borehole logs and geophysical data consisting in microtremor measurements and down-hole.

These measurements identified resonant frequencies occurring in the range of 0.7-3.0 Hz. These frequency peaks are related to the presence of a velocity contrast at depth between the San Nicandro silts and the Madonna della Neve breccias, as indicated by the performed deep boreholes. Thanks to analytical, numerical, and geostatistical techniques, we identified the main impedance contrast at approximately 210 m depth from the top of the hill, much deeper than previous studies. These new findings allowed to create an accurate and consistent subsoil model summarized by two geological cross-sections of the Castelnuovo ridge, showing that the seismic site effects at the Castelnuovo village are mainly related to stratigraphic amplification.
Estimating urban sensible heat flux using satellite-based data
Authors: Rios Gabriel , Ramamurthy Prathap
Published: March 2021

A model for calculating sensible heat flux (QH) – a primary component of the urban surface energy budget - is presented here. Remote sensing data from the NOAA GOES-16 satellite and a high-resolution land cover dataset are used as inputs to calculate the spatio-temporal variability in urban sensible heat flux. The primary motivation for this model is to present a cost-effective approach to calculate QH independent of traditional flux observations and computational methods. The GOES-16 satellite data, which has a moderate spatial and high temporal resolution (2 km square at 5 minute intervals) enables the estimation of QH over highly heterogeneous urban areas. The model is constructed using an iterative algorithm that uses surface layer turbulence parameterization to solve for QH as a function of the enterprise GOES-16 Land Surface Temperature product, an urban air temperature model, publicly-accessible ground observations, and the National Land Cover Database (NLCD). Preliminary model validation was performed over a five-month period in 2019. Three (3) ground flux stations in the New York City metro area with varying degrees of urbanization were used for model validation. Statistics from validation found an RMSE of 42.9 W-m-2, a mean bias of 12.9 W-m-2, and an R2 of 0.80. Validation results demonstrate that the algorithm shows good correlation with observed values, suggesting that satellite data can be used as an accessible and cost-effective option to estimate QH in urban areas.
Export of newly oxygenated Labrador Sea Water at 53N
Authors: Koelling Jannes , Atamanchuk Dariia , Karstensen Johannes , Wallace Douglas W.R.
Published: March 2021

Most of the life-sustaining oxygen found in the global deep ocean is supplied in one of only a handful of key regions around the globe, such as the Labrador Sea in the subpolar North Atlantic. Here, oxygen is supplied directly to the deep ocean during the formation of Labrador Sea Water (LSW), when convective mixing continuously brings low-oxygen deep water towards the surface and into contact with the atmosphere. The continuous exchange between the surface and deep ocean during convection can bring newly oxygenated waters as deep as 2000m. Although the associated oxygen uptake has been observed and quantified, and the resulting oxygen-rich water mass in the deep ocean is readily detected throughout the Atlantic Ocean, relatively little is known about the exact mechanisms and timing of its export out of the basin.

In this talk, we will present a novel dataset of oxygen sensors deployed within the boundary current at the exit of the Labrador Sea to investigate oxygen variability in the deep ocean. This is the first time that a continuous time series of oxygen has been collected in the boundary current of the Labrador Sea, with a total of 10 sensors deployed on 4 moorings from 2016 to 2020. The sensors at 600m depth show a sudden change in oxygen, temperature, and salinity in the spring, which we discuss in relation to deep convection in the interior. We also use data from Argo floats to analyse export pathways from the convection region to the location of the moorings. Our results give new insights into how the oxygen taken up in the central Labrador Sea subsequently spreads into the global deep ocean, and lay the basis for future work on quantifying variability of oxygen transport at the exit of the Labrador Sea.
Onset of Carnegie Ridge subduction from low-temperature thermochronology
Authors: Margirier Audrey , Strecker Manfred , Reiners Peter , Casado Ismael , Thomson Stuart , George Sarah , Alvarado Alexandra
Published: March 2021

Cenozoic growth of the Andes has been strongly influenced by subduction dynamics, inherited crustal heterogeneities, and the superposed effects of climate. Subduction of the Carnegie Ridge in Ecuador has impacted late Cenozoic magmatism and tectonic activity, including the formation of a crustal sliver escaping northward. However, the relationship between ridge subduction and topographic growth has remained unclear. We present new thermochronological data from the Western Cordillera of Ecuador to (1) pinpoint the timing of ridge subduction, and (2) evaluate the role of ridge subduction in prompting growth of the Ecuadorian Andes. Time-temperature inverse modeling of our results shows two phases of cooling separated by tectonic quiescence. The first cooling phase immediately post-dates magmatism in the Western Cordillera, and hence we attribute it to magmatic cooling. The second cooling phase starts at ~6-5 Ma. This we associate with onset of enhanced exhumation at this time in the Western Cordillera, synchronous with the last cooling phase in the Eastern Cordillera. Based on our thermal modeling and thermochronological age patterns along geological cross-sections we propose that recent crustal shortening and rock uplift triggered exhumation of Western Ecuadorian Andes starting at ~6-5 Ma. We suggest that the onset of Carnegie Ridge subduction in the latest Miocene increased the coupling at the subduction interface and promoted shortening and regional rock uplift in the northern Andes. Overall, our new thermochronological results highlight the pivotal role of bathymetric anomalies in distinct upper-plate deformation processes at non-collisional convergent plate margins.
Data-driven automatic predictions of avalanche danger in Switzerland
Authors: Pérez-Guillén Cristina , Hendrick Martin , Techel Frank , van Herwijnen Alec , Volpi Michele , Tasko Olevski , Pérez-Cruz Fernando , Obozinski Guillaume , Schweizer Jürg
Published: March 2021

Avalanche forecasting implies predicting current and future snow instability in time and space. In Switzerland, avalanche bulletins are issued daily during the winter season to warn the public about the avalanche hazard, described by region with one of five danger levels. Assessing avalanche danger is by large a data-driven, yet experience-based decision-making process. It involves analysing a multitude of data diverse in scale – time and space, and concluding by expert judgment on the avalanche scenario. Numerous statistical models were developed in the past, but rarely applied due to limited usefulness in operational forecasting. Modern machine learning techniques open up new possibilities for developing support tools for operational avalanche forecasting. With this aim, we developed a data-driven approach based on the supervised Random Forest (RF) classifier to automatically predict the danger level for dry-snow avalanche conditions in the Swiss Alps. A large database of more than 20 years of meteorological data and modelled snow stratigraphy data obtained with the numerical snow cover model SNOWPACK were used to train the RF algorithm. We optimized the model and selected the best set of input features that combine meteorological variables and features extracted from the simulated profiles, resampled at the same daily resolution as the forecasts. Our target variable was the regional danger level forecast in the public bulletin. We evaluated the predictive performance of the RF model with an independent test set with data of two winter seasons (2018-2019 and 2019-2020). The test set accuracy was 72 %, which is slightly lower than the accuracy estimate of the public forecasts (about 76 %). Given this uncertainty in our target variable, we trained an optimized RF model on a subset containing so-called verified avalanche danger levels. The test set accuracy then increased to 80 %. During the winter season 2020-2021, both RF models were tested in operational setting and automatically predicted a ‘nowcast’ and a ‘forecast’ in real-time.  In parallel, we also tested a deep recurrent neural network model, which used a 7-days time series with 3-hours time resolution as input and also predicted the avalanche danger level. We present a comparison of the performance of the three models. This is one of the first times that a data-driven approach is tested in real-time as a feasible tool for operational avalanche forecasting.
Inishell 2.0: Semantically driven automatic GUI generation for scientific models
Authors: Bavay Mathias , Reisecker Michael , Egger Thomas , Korhammer Daniela
Published: March 2021

As numerical model developers, we have experienced first hand how most users struggle with the configuration of the models, leading to numerous support requests. Such issues are usually mitigated by offering a Graphical User Interface (GUI) that flattens the learning curve. This requires however a significant investment for the model developer as well as a specific skill set. Moreover, this does not fit with the daily duties of model developers. As a consequence, when a GUI has been created -- usually within a specific project and often relying on an intern -- the maintenance either constitutes a major burden or is not performed. This also tends to limit the evolution of the numerical models themselves, since the model developers try to avoid having to change the GUI.

To circumvent that problem, we have developed Inishell [1], a C++/Qt application based on an XML description of the inputs required by the numerical model that generates a GUI on the fly. This makes maintenance of the GUI very simple and enables users to easily get an up-to-date GUI for configuring the numerical model. The first version of this tool was written almost ten years ago and showed that the concept works very well for our own surface processes models. A full rewrite offering a more modern interface and extended capabilities is presented here.

 

[1] Bavay, M., Reisecker, M., Egger, T., and Korhammer, D., “Inishell 2.0: Semantically driven automatic GUI generation for scientific models”, Geosci. Model Dev. Discuss. [preprint], https://doi.org/10.5194/gmd-2020-339, in review, 2020.
Daily cyclicity in bivalve shell chemistry: Paleo-weather record or circadian rhythm?
Authors: de Winter Niels , Fröhlich Lukas , Killam Daniel , Boer Wim , de Nooijer Lennart , Reichart Gert-Jan , Schöne Bernd
Published: March 2021

Bivalve shells have a long-standing reputation as archives for high-resolution (seasonal scale) (paleo)climate variability due to their incremental growth, yielding accurate shell chronologies, and their abundance, diversity, and high preservation potential in the fossil record (Schöne and Surge, 2012). Capitalizing on innovations in geochemical techniques, high-resolution sclerochronology can now resolve changes in bivalve shell chemistry beyond the daily resolution (e.g. Sano et al., 2012; Warter et al., 2018). When applied on fossil shells, these ultra-high-resolution records have the potential to bridge the gap between climate and weather reconstructions and yield unprecedented information about bivalve paleobiology, extreme weather events in past climates and even astronomical cycles (Warter and Müller, 2017; de Winter et al., 2020; Yan et al., 2020).

However, studies of sub-daily scale shell chemistry are almost exclusively limited to giant clams (Tridacna spp.), due to their high growth rates. It is hitherto unknown if and how such diurnal cycles in chemistry differ in other genera across the bivalve clade and/or whether they are exclusive to photosymbiotic clams. In addition, it is not clear whether the daily cycles are formed in response to environmental conditions (e.g. light or temperature sensitivity) or reflect circadian rhythms.

To answer these questions, we combine ultra-high-resolution (hourly scale) Laser Ablation ICP-MS trace element profiles through shells of various tridacnid species from the tropical Gulf of Aqaba with profiles through the giant scallop (Pecten maximus) from the temperate Atlantic coast of northwestern France. We observe trace element cycles on in the daily frequency domain in both tridacnids and pectinids. This shows that these diurnal cycles are formed regardless of shell mineralogy (aragonite vs. calcite), living environment (tropical inter-tidal vs. temperate sub-tidal) and occur in highly unrelated bivalve taxa. Our data helps the interpretation of similar records from fossil shells in terms of past (extreme) weather events, climate, and shell growth.

 

References

de Winter, N. J. et al. Paleoceanography and Paleoclimatology 35, e2019PA003723 (2020).

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Schöne, B. R. & Surge, D. M. Treatise Online 24, Volume 1, Chapter 14 (2012).

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Investigating methods of phosphorus recovery from eutrophic lakes through hypolimnetic withdrawal and purification
Authors: Silvonen Soila , Niemistö Juha , Myyryläinen Jerry , Huotari Simo , Nurminen Leena , Horppila Jukka , Jilbert Tom
Published: March 2021

As global reserves of phosphorus (P) become scarce, recycling of P will be key to sustainable food production in future. The hypolimnetic withdrawal and purification circuit (HWPC) is a novel method that aims to remove and capture P accumulated in the near-bottom water of eutrophic lakes. Similar to the basic principle of wastewater treatment, the lake water is treated for the precipitation of P and other elements, and the formed particles are collected in a filtering unit while the purified water flows back into the lake. The method has been tested in a pilot project at Lake Kymijärvi, southern Finland.

In the current study, we observed the efficiency of three different water treatments in the HWPC in terms of P precipitation: 1) water aeration; 2) aeration + Ca(OH)2 addition; 3) aeration + tannin-based biopolymer addition. Moreover, we studied the chemical composition of the precipitate formed in each treatment to understand its potential for P recycling. The aim of the study was to provide a better understanding to further develop and apply techniques to recover and recycle P from eutrophic lakes.
Understanding Solar Wind Formation by Identifying the Origins of In Situ Observations 
Authors: Wallace Samantha , Viall Nicholeen M. , Arge Charles N.
Published: March 2021

Solar wind formation can be separated into three physical steps – source, release, and acceleration – that each leave distinct observational signatures on plasma parcels.  The Wang-Sheeley-Arge (WSA) model driven by Air Force Data Assimilative Photospheric Flux Transport (ADAPT) time-dependent photospheric field maps now has the ability to connect in situ observations more rigorously to their precise source at the Sun, allowing us to investigate the physical processes involved in solar wind formation.   In this talk, I will highlight my PhD dissertation research in which we use the ADAPT-WSA model to either characterize the solar wind emerging from specific sources, or investigate the formation process of various solar wind populations.  In the first study, we test the well-known inverse relationship between expansion factor (fs) and observed solar wind speed (vobs) for solar wind that emerges from a large sampling of pseudostreamers, to investigate if field line expansion plays a physical role in accelerating the solar wind from this source region.  We find that there is no correlation between fs and vobs at pseudostreamer cusps. In the second study, we determine the source locations of the first identified quasiperiodic density structures (PDSs) inside 0.6 au. Our modeling provides confirmation of these events forming via magnetic reconnection both near to and far from the heliospheric current sheet (HCS) – a direct test of the Separatrix-web (S-web) theory of slow solar wind formation.  In the final study, we use our methodology to identify the source regions of the first observations from the Parker Solar Probe (PSP) mission.  Our modeling enabled us to characterize the closest to the Sun observed coronal mass ejection (CME) to date as a streamer blowout.  We close with future ways that ADAPT-WSA can be used to test outstanding questions of solar wind formation.
Rain Droplets Size Distributions Statistical analysis for pre-Monsoon and Monsoon Season over the Western Ghats
Authors: Kumar Amit , Srivastava Atul Kumar , Chakravarty Kaustav , Srivastava Manoj Kumar
Published: March 2021

Four years (2015-2018), Joss-Waldvogel disdrometer (JWD) data are utilized for the statistical analysis of Raindrop size distribution (RSD) of pre-monsoon and monsoon season over the Western Ghats. JWD Instrument installed at High Altitude Cloud Physics Laboratory (HACPL, 17.92°N, 73.66°E), Mahabaleshwar in the core of heavy rainfall region of Western Ghats. Variation in raindrop size distribution characteristics features in pre-monsoon and monsoon season for convective and stratiform precipitation of windward side of Western Ghats analysis, using long-term in-situ JWD instrument data done. Convective and stratiform rainfall classification is based on the number of concentrations of rain droplets and rain rates. Tropical Rainfall Measuring Mission (TRMM) and ERA-Interim data sets are also integrated with disdrometer data to establish microphysical and dynamical features of pre-monsoon and monsoon season rain. Long-term trends of rain droplet size spectra are not studied until now over the Western Ghats.   Rain droplet spectra of pre-monsoon and monsoon seasons show notable differences. The rain droplets of monsoon display considerably higher divergence compared to pre-monsoon rainfall.  Monsoon rainfall has a higher concentration of smaller drops, while pre-monsoon rainfall contains a significantly higher concentration of large droplets. RSD classified on the rain rate demonstrates a higher mass-weighted mean diameter (Dm) and a lower normalized intercept parameter (log10Nw) in monsoon than winter. Similarly, the Diurnal variation of RSD reveals higher Dm with a lower value of log10Nw in pre-monsoon season. Also, in both seasons, the higher value of mean Dm in convective precipitation than stratiform.  Convective activities with increased ground temperature alter RSD in pre-monsoon season rather than monsoon season through droplet classification, evaporation, and collision-coalescence processes.
Multi-objective Optimization of Catchment Reforestation Robust to Uncertainty in Bayesian-Calibrated Watershed Model Parameters
Authors: Smith Jared , Lin Laurence , Quinn Julianne , Band Lawrence
Published: March 2021

Urban land expansion is expected for our changing world, which unmitigated will result in increased flooding and nutrient exports that already wreak havoc on the wellbeing of coupled human-natural systems worldwide. Reforestation of urbanized catchments is one green infrastructure strategy to reduce stormwater volumes and nutrient exports. Reforestation designs must balance the benefits of flood flow reduction against the costs of implementation and the chance to exacerbate droughts via reduction in recharge that supplies low flows. Optimal locations and numbers of trees depend on the spatial distribution of runoff and streamflow in a catchment; however, calibration data are often only available at the catchment outlet. Equifinal model parameterizations for the outlet can result in uncertainty in the locations and magnitudes of streamflows across the catchment, which can lead to different optimal reforestation designs for different parameterizations.

Multi-objective robust optimization (MORO) has been proposed to discover reforestation designs that are robust to such parametric model uncertainty. However, it has not been shown that this actually results in better decisions than optimizing to a single, most likely parameter set, which would be less computationally expensive. In this work, the utility of MORO is assessed by comparing reforestation designs optimized using these two approaches with reforestation designs optimized to a synthetic true set of hydrologic model parameters. The spatially-distributed RHESSys ecohydrological model is employed for this study of a suburban-forested catchment in Baltimore County, Maryland, USA. Calibration of the model’s critical parameters is completed using a Bayesian framework to estimate the joint posterior distribution of the parameters. The Bayesian framework estimates the probability that different parameterizations generated the synthetic streamflow data, allowing the MORO process to evaluate reforestation portfolios across a probability-weighted sample of parameter sets in search of solutions that are robust to this uncertainty.

Reforestation portfolios are designed to minimize flooding, low flow intensity, and construction costs (number of trees). Comparing the Pareto front obtained from using MORO with the Pareto fronts obtained from optimizing to the estimated maximum a posteriori (MAP) parameter set and the synthetic true parameter set, we find that MORO solutions are closer to the synthetic solutions than are MAP solutions. This illustrates the value of considering parametric uncertainty in designing robust water systems despite the additional computational cost.
Projected changes to severe thunderstorm environments as a result of 21st century warming in CORDEX-CORE simulations
Authors: Glazer Russell , Torres‑Alavez José Abraham , Giorgi Filippo , Coppola Erika , Das Sushant , Ashfaq Moetasim , Sines Taleena
Published: March 2021

            Dangerous weather related to severe thunderstorms including tornadoes, high-winds, and hail cause significant damage globally to life and property every year. Yet the impact on these storms from a warming climate remains a difficult task due to their small scale and transient nature. Here, we present a study in which the changes to the large-scale environments in which severe thunderstorms form were investigated during 21st century warming (RCP2.6 and RCP8.5) in a group of RegCM CORDEX-CORE simulations. Severe potential is measured in terms of CAPE (Convective Available Potential Energy) and shear during the severe seasons in three regions which are known to currently be prone to severe hazards: North America, the southeastern coast of South America east of the Andes, and eastern India and Bangladesh. In every region environments supportive for severe thunderstorms are projected to increase during the warm season months in both RCP2.6 and RCP8.5 during the 21st century. The number of days supportive for severe thunderstorms increases by several days per season over the vast majority of each region by the end of the century. In the case of RCP2.6, where greenhouse gas forcing is relatively weak compared to RCP8.5, there is still a consistent positive trend in the impact on severe days. The simulations using RCP8.5 forcing show large changes to the annual cycle of severe weather as well as the number of days supportive for severe weather per season. In some regions, like for example Northern Argentina along the Andes mountains, the number of days with severe conditions present increases by nearly 100% by the end of the century. Analyzing the CAPE and shear trends during the 21st century we find seasonal and regionally specific changes driving the increased severe potential. 21st century surface warming is clearly driving a robust increase in CAPE in all regions, however poleward displacement of vertical shear in the future leads to the movement of severe environments over North America and South America. We would also like to present a preliminary look at the next phase of this project which will apply similar methods to an ensemble of 11o Euro-CORDEX simulations to investigate severe conditions over the European region in the future.