bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnitude estimates of earthquakes induced by the geothermal stimulations in Espoo/Helsinki, southern Finland: a comparison of different approaches
Authors: Sadeghi-Bagherabadi Amir , Eulenfeld Tom , Vuorinen Tommi A.T. , Rintamäki Annukka E. , Hillers Gregor
Published: March 2022

In 2018 and 2020, two weeks-long geothermal reservoir stimulations were performed some 6 km below the Helsinki capital area, Finland. The seismic activity was recorded by a set of surface broadband sensors and 100 geophones installed by the Institute of Seismology, University of Helsinki, as well as Finnish National Seismic Network stations. The local magnitudes (ML) of the recorded earthquakes are estimated using a Finnish local magnitude scale and the local magnitude of the largest induced event was 1.8. We apply three different approaches for estimation of moment magnitudes (MW) to a data base of ~400 induced seismic events from the 2018 stimulation to explore the variability and sensitivity of the magnitude estimates. This is important for real-time monitoring and decision making when the induced event magnitudes approach the pre-defined magnitude limit, and to assess which trends can be robustly associated to earthquake source physics. (1) We employ a time-domain calculation of source parameters based on the application of Parseval's theorem to the integrals of the squared spectral displacement and velocity for the horizontal S-wave trains. The time window between the S-wave arrival time and twice the length of the S-wave travel time is considered for the S-wave train isolation. (2) We obtain moment magnitude estimates from an inversion of 50 s long three-component envelopes based on radiative transfer. (3) We apply a moment tensor inversion to 0.71 s long P and 0.81 s long S-wave signals. We fit a linear ML-MW conversion model to the values obtained from the different approaches. Considering the available local magnitude range between –0.5 and 1.8, a comparison of the linear conversion models shows that the moment magnitudes form the envelope inversion are systematically larger by ~0.2 units compared to those obtained from the moment tensor inversion. While the moment magnitudes determined by the time-domain calculation consistently exceed those of the envelope inversion for small local magnitudes (by ~0.2 units), they tend to yield similar estimates towards the larger local magnitudes. Other source parameter systematics include that the smallest seismic moment is obtained with the moment tensor inversion, and the largest with the time-domain equivalent of the spectral integrals. An initial extension of the analysis to 2020 data yields ML-MW as well as corner frequency-MW scaling relations that are, interestingly, different compared to the 2018 results; we will present updated results that inform about the reliability of these trends.
Impact of tides on the North Western European shelf carbon pump
Authors: Kossack Jan , Mathis Moritz , Schrum Corinna
Published: March 2022

It has been suggested that continental shelves disproportionally contribute to global oceanic CO2 uptake from the atmosphere, in particular through the efficient CO2 sinks of the biologically productive mid- and high latitude shelves. For the North Western European Shelf (NWES), contributions of different biological and hydrodynamic drivers of the shelf carbon pump, however, remain poorly constrained. We here use the flexible coupled hydrodynamic-biogeochemical modeling system SCHISM-ECOSMO to investigate how tidal forcing, as one of the dominant hydrodynamic features on the NWES, influences the efficiency of the continental shelf pump. Tidal impacts on biological productivity and carbon cycling are assessed by comparing hindcast simulations with and without tidal forcing. We show that tides substantially increase net primary productivity on the NWES and find a significant contribution from vertical mixing induced by internal tides. Our results further demonstrate that the enhanced productivity and inorganic carbon sequestration in the tidal scenario translates into an increased oceanic CO2 uptake, even though tidal currents reduce particulate carbon deposition in the shelf sediments. This suggests that tides play an important role for the efficiency of the continental shelf pump by promoting net carbon export from the NWES to the adjacent North Atlantic.
Effects of Sudden Stratospheric Warmings on the observed near-surface wind speed in the Northern Hemisphere, 1961-2021
Authors: Utrabo-Carazo Eduardo , Azorin-Molina Cesar , Dunn Robert J. H. , Aguilar Enric , Brunet Manola
Published: March 2022

Sudden Stratospheric Warmings (SSW) are known to have impacts on the tropospheric atmospheric circulation that can persist up to 60 days. The aim of this work is to evaluate the influence of SSW on both observed mean wind speed and daily peak wind gusts across the Northern Hemisphere for 1961-2021. A set of 26 SSW with tropospheric response, including split (12) and displaced (14) events, are chosen for this matter. Daily wind speed means and peak gust data are retrieved from the quality-controlled and sub-daily station dataset: HadISD. The ultimate goal will be to prove the ability of SSW as possible source of predictability in the medium term for surface wind speed across the Northern Hemisphere, which would have direct applications in areas such as: wind-power generation, agriculture and air quality, among many other socioeconomic and environmental issues.
LAFE and LAFO: New experimental and observational investigations of land-atmosphere feedback processes
Authors: Späth Florian , Lange Diego , Behrendt Andreas , Abbas Syed Saqlain , Brewer Alan , Senff Christoph , Weber Tobias , Streck Thilo , Wulfmeyer Volker
Published: March 2022

The exchange of energy, moisture and momentum between the atmosphere and the land-surface as well as the associated feedback processes are decisive for the development of the planetary boundary layer. Inaccurate representation and parameterization of these processes are a weakness of current weather and climate models. Improvements in these areas will contribute significantly to better simulations of cloud formation on all temporal and spatial scales. This requires simultaneous measurements of the land-atmosphere system in all compartments. Both the LAFE and the new LAFO design with their instrument synergies have already made important contributions to this. With comparisons between model parameterizations and observations, e.g. the applicability of the Monin-Obukhov similarity theory (MOST) in the case of natural heterogeneous land surface can be investigated or new parameterizations can be developed.

The Land-Atmosphere Feedback Experiment (LAFE, Wulfmeyer et al., 2018) was performed in August 2017 as a measurement campaign at the Atmospheric Radiation Measurements (ARM) Program Southern Great Plains site in Oklahoma, USA. For boundary layer observations, scanning Doppler lidar systems for wind measurements, rotational Raman lidar for temperature and humidity measurements, and differential absorption lidar for water vapor measurements were setup. At the land-surface, meteorological and plant dynamics variables, energy balance, and soil moisture and temperature were recorded at eddy covariance stations. These measurements are also executed at the Land-Atmosphere Feedback Observatory (LAFO, lafo.uni-hohenheim.de) at the University of Hohenheim in Stuttgart (Germany) to collect long-term time series in addition to field experiments. Here, lidar measurements are operationally operated and complemented by measurements from a Doppler cloud radar. At the land surface we measure with eddy covariance stations and a network of soil moisture and temperature sensors and the vegetation status is recorded in the study area. This sensor synergy in LAFO is prototype for GLAFOs (Gewex LAFOs, Wulfmeyer et al. 2020) to establish these measurements in different climate regions in the world.

In this contribution, we present the measurement concept and how observations can be used to study and improve boundary layer and turbulence parameterizations. We demonstrate this with measurement results from LAFE and LAFO with estimates of fluxes determined by combining the moisture, temperature, and wind profiles near the ground, allowing the derivation of appropriate similarity relationships for both entrainment fluxes and MOST.

 

Wulfmeyer et al., 2018, doi: 10.1175/BAMS-D-17-0009.1

Wulfmeyer et al. 2020, GEWEX Quarterly Vol. 30, No. 1.
Understanding the recent evolution of a small Alpine glacier: from geodetic mass balance reconstruction (1991-2020) to local variability of glaciers retreat.
Authors: Mondardini Luca , Perret Paolo , Gottardelli Simone , Frasca Marco , Troilo Fabrizio
Published: March 2022

High Alpine environments are rapidly changing in response to climate change, and understanding the evolution of small glaciers is a crucial step to investigate future water availability for populations that inhabits these areas. With an average loss of 1.6 km2 of regional glacier area every year, Aosta Valley is predicted to lose most of its glaciers before the end of the century. With this study, we present a comprehensive analysis of a small glacier’s recent mass balance evolution (1991-2020) where no specific previous mass balance data was available. To do so, we combined historical data (topographic surveys and LiDAR DEMs of the area) with newly acquired satellite stereo imagery and aerophotogrammetric surveys to reconstruct different digital elevation models of the Thoula glacier (0.52 Km2), located on the Italian side of the Mont-Blanc Massif. The ice volume loss that occurred over this period was assessed by accomplishing two GPR surveys to investigate the ice thickness and the underlying bedrock. The Thoula glacier shows a significantly lower loss of volume in comparison to other glaciers located in the Aosta Valley region as well as most of the WGMS (Word Glacier Monitoring Service) reference glaciers for Central Europe. Particular weather-climatic conditions of the Mont Blanc Massif area, generally characterized by a greater amount of snowfall, could explain the observed differences, however, the present study shows how understanding spatio-temporal local variability of small glaciers can significantly contribute to recognizing different regional patterns developing in response to climate change.
Environmental and climate change in Sierra Nevada (S Spain) during the latest Pleistocene and Holocene 
Authors: Jiménez-Moreno Gonzalo , López-Avilés Alejandro , García-Alix Antonio , Ramos-Román María J. , Camuera Jon , Mesa-Fernández Jose Manuel , Jiménez-Espejo Francisco J. , López-Blanco Charo , Carrión José S. , Anderson R. Scott
Published: March 2022

In this study, we studied palynomorphs from the alpine record from Laguna Seca in Sierra Nevada, southern Spain to investigate the response of forests and lake environments in the western Mediterranean area to climate changes and to human impact during the latest Pleistocene and Holocene. Xerophyte herbs such as Artemisia, Ephedra, and Amaranthaceae are highest during the late Bölling-Allerod (BA) and Younger Dryas (YD) indicating aridity. Poaceae (grasses) are maximum in the BA and Early Holocene, probably indicating expansion in the barren areas left by glaciers after deglaciation. Forest abundance and composition, in particular of deciduous Quercus and Pinus species indicates maximum humidity during the Early Holocene and aridification in the Middle and Late Holocene. Microcharcoal analysis done on the palynological preparations agrees with the vegetation changes, showing maxima in the Early and Middle Holocene and a decrease in the Late Holocene when the Mediterranean vegetation, and thus fuel availability, diminished. The record of Laguna Seca is particularly interesting with respect to the algae and other aquatic microscopic remains. Pediastrum algae only occurred and showed very high abundances during the end of Heinrich Stadial 1 and beginning of the BA, probably indicating deepest lake conditions with deglaciation. Botryococcus, Debarya, Spirogyra and Zygnema algae also peaked at that climate transition, also supporting lake conditions. Botryococcus increased during the Early Holocene, while the rest of the algae almost vanished, which could indicate that the lake became shallower but very productive until 8200 cal yr BP. From then on, the lake level lowered and became a seasonal lake in the Middle-Late Holocene transition.
On the forced response and decadal predictability of the North Atlantic Oscillation
Authors: Christiansen Bo , Yang Shuting , Matte Dominic
Published: March 2022

We investigate the forced response of the North Atlantic Oscillation (NAO)  in large ensembles of climate models including simulations with historical  forcings and initialized decadal hindcasts.  The forced NAO in the  CMIP6 historical ensemble correlates significantly with observations after 1970. However, the forced NAO shows an apparent non-stationarity with significant correlations to observations only in the period after 1970 and in the period before 1890. We demonstrate that such apparent non-stationarity can be due to chance even when models and observations are independent. We find only weak evidence that initialization improves the skill of the NAO on decadal time-scales. Neither of the historical ensembles including only natural forcings, well-mixed greenhouse-gases, or anthropogenic aerosols show any skillful NAO. Our results question the possibility of useful decadal predictions of the NAO.
Pattern analysis of seismicity around Mavrovo lake: a case study for the period July 2020 - November 2021
Authors: Chernih-Anastasovska Dragana , Drogreshka Katerina , Najdovska Jasmina , Pekevski Lazo , Sinadinovski Cvetan
Published: March 2022

Two moderate earthquakes with magnitude ML5.0 happened on the 11th of November 2020 near the Mavrovo lake in northwestern Macedonia. Mavrovo lake is an artificial lake with a dam built between 1947 and filled by 1953. Its maximum length is 10km, width is 5km and depth is 50m. We try to investigate the factors which might be causing earthquakes, for example, local geology and seismotectonic regime in the region.

Seismic events of such size can have various sequences of foreshocks and aftershocks, which mostly depend on the earthquake mechanism. In this case study, a numerical analysis was done for the first time from the list of events reported by the Skopje Seismological observatory, that occurred some six months prior to the main events and one year after, till November 2021.

 

A list of 180 earthquakes registered by the local and regional stations with magnitudes equal or greater than ML1.7 was analyzed in more detail in terms of temporal and spatial distribution around the lake, in a polygon area defined by geological features. No statistically significant clustering of events was noticed in the foreshock period from July 2020. In the aftershock period, the most numerous events lasted about a month after the main events. However, there was another period of increased seismicity during March 2021, followed by a gradual decrease onwards.

The preliminary distribution of epicenters was mainly along the terrain of Radika river and close monitoring continues to establish possible longer-term variations of seismicity. Comparative analysis with various periods will be also considered in order to determine any patterns of seismicity.
Impact of the climate change on the crop water deficiency at the regional scale: study case in Bourgogne Franche-Comté, France.
Authors: Yvoz Séverin , Lechenet Martin , Amiotte-Suchet Philippe , Ubertosi Marjorie
Published: March 2022

In the Bourgogne Franche-Comté region, climate change will lead to an increase of the field evapotranspiration during the crop cycle and a modification of the rainfall distribution within the year, leading to longer and more intense drought periods in summer. This will increase the crop water requirement, while reducing water availability and accessibility, which could negatively impact agricultural productivity and stability. It is thus necessary to evaluate actual and future water deficiency in a way to develop and implement adapted responses (new farming practices, new crops, water storage…). Based on simulated weather data (rainfall and potential evapotranspiration) integrating the effect of climate change until 2100, soil characteristics (texture and depth) and crop water requirement, we estimate the daily water balance at the scale of the Bourgogne Franche-Comté region, France. We use weather data at an 8*8 square-kilometres grid and soil water capacity is estimated at the soil map unit using the methodology developed by Bruand et al. (2004). This methodology estimates the water capacity of each layer of the soil unit based on their texture class (Aisne triangle) and removing the proportion of gravels and rocks considering that their contribution to water storage is negligible. For the 10 main crops of the region in terms of field area (i.e. grassland, winter wheat, winter barley, winter oilseed rape, spring barley, maize, soybean, sunflower, winter peas and spring peas), we calculate the water balance using the methodology developed by Jacquart and Choisnel (1995) at the scale of the intersection between the weather grid and the soil map unit in a way to represent homogeneous pedoclimatic territories. The soil water capacity is thus divided in two reservoirs with no horizontal transfer. Water from the first reservoir (40% of the soil water capacity) is easily accessible to the crop while water from the second reservoir is less and less accessible as the reservoir is emptied. At a daily step, the meeting of the crop water requirement is estimated regarding the water available in the soil reservoirs and the rainfalls. This study enables to estimate the actual water deficiency of the main crops and its potential increase due to climate change. We can thus identify crops that could not be cropped anymore without irrigation in some area and estimate the water required if we want to keep these crops in the future. These results are also important to evaluate if it is possible to developed new practices or water storage in response to the effects of climate change. Our approach allows as well to evaluate and anticipate the possibility to implement new crops requiring less water, avoiding the drought periods or able to access more water in the soil. These results will allow the agricultural sector to develop outlets for these new crops.
Flood flow in a proglacial outwash plain - quantifying spatial extent and frequency of inundation from time-lapse imagery
Authors: Hiller Clemens , Walter Lukas , Helfricht Kay , Weisleitner Klemens , Achleitner Stefan
Published: March 2022

High mountain environments have shown substantial geomorphological changes forced by rising temperatures in recent decades. As such, paraglacial transition zones in catchments with rapidly retreating glaciers and abundant sediments are key elements in high alpine river systems and promise to be revealing, yet challenging, areas of investigation for the quantification of current and future sediment transport. In this study, we explore the potential of semi-automatic image analysis to detect the extent of the inundation area and corresponding inundation frequency in a proglacial outwash plain (Jamtal valley, Austria) from terrestrial time-lapse imagery. We cumulated all available records of the inundated area from 2018-2020 and analysed the spatial and temporal patterns of flood flows. The approach presented here allows semi-automated monitoring of fundamental hydrological/hydraulic processes in an environment of scarce data. The pixel classification based on greyscale values from oblique hourly recordings returned plausible results of the spatial and temporal variability of surface runoff in the investigated glacier forefield. The image sets, processed in ImageJ, allowed geo-rectification to produce inundation frequency maps. Meteorological and discharge data from downstream measuring stations was consulted to interpret our findings. Runoff events and their intensity were quantified and attributed to either pronounced ablation, heavy precipitation, or a combination of both. We also detected an increasing degree of channel concentration within the observation period. The maximum inundation from one event alone took up 35% of the analysed area. About 10% of the observed area presented inundation in 60-70% of the analysed images. In contrast, 60-70% of the observed area was inundated in fewer than 10% of the analysed period. Despite some limitations in terms of image classification, prevailing weather conditions and illumination, the derived inundation frequency maps provide novel insights into the evolution of the proglacial channel network.
Hydroclimate variability in the Czech Republic studied through subjective and objective classifications of atmospheric circulation
Authors: Řehoř Jan , Brázdil Rudolf , Trnka Miroslav , Lhotka Ondřej , Balek Jan , Štěpánek Petr , Zahradníček Pavel
Published: March 2022

Investigation of the relationship between climatological variables and circulation patterns expressed by various classifications of circulation types is a key procedure in synoptic climatology. This study provides new insights into circulation drivers of hydroclimate based on an analysis of precipitation and soil drought in multiple parts of the Czech Republic with respect to the subjective classification of the Czech Hydrometeorological Institute and objective classification based on the flow strength, flow direction, and vorticity during the 1961–2020 period. Circulation types are investigated in regard to their contributions to the total precipitation, mean daily precipitation totals, and precipitation probability. Types with a westerly airflow and a trough over Central Europe exhibit the highest proportions in precipitation totals. Types with a cyclone over Central Europe, especially combined with a northwestern or northeastern airflow, result in the highest daily mean totals and precipitation probability. Types with a southwestern airflow transport more precipitation to western parts of the Czech Republic, while those with a northeastern airflow transport more precipitation to the eastern parts, with a slight seasonal shift in the gradient axis between winter and summer. Circulation drivers of drought episodes are investigated based on soil-drought values calculated from the SoilClim model. Increased frequencies of north-eastern anticyclonic types, and decreased frequencies of directional and cyclonic are important for the origin and course of soil-drought episodes. In addition, the suitability of both classifications for long-term trends analysis is investigated.
Quantifying lava temperature with a low-cost silicon-based thermal camera
Authors: Marks Joshua , Kuhn Jonas , Fuchs Christopher , Bobrowski Nicole , Platt Ulrich
Published: March 2022

An important characteristic quantity of volcanoes is the temperature of their magma. It depends on the magma composition, the volcanic activity, and partly affects the composition of magmatic gases that are later released to the atmosphere. Lava temperature measurements are thus desired for a manifold of volcanic studies at volcanoes including open magma-atmosphere interface (e.g. lava lakes).

The mostly used commercially available thermal cameras for the relevant temperature range (ca. 600-1200 °C) are still rather expensive, bulky, and have a limited spatial resolution.

We present an approach to use a compact (‘point and shoot’) consumer digital camera with a silicon based detector as a thermometer to record the spatial temperature distribution and variations of volcanic lava. Silicon detectors are commonly sensitive in the near infrared wavelength range (until ca. 1100 nm), which readily allows measurements of temperatures above ca. 500 °C. The camera is modified to block the visible spectrum and the remaining colour filter (Bayer filter) characteristics are used to infer the temperature from differential intensity measurements.

In the frame of this work, we performed a sensitivity study and calibrated the camera with a heated wire in the range of 600-1100 °C. Besides the advantages of the low costs, superior mobility and simple handling, the 16 megapixel spatial resolution of the temperature measurement allows resolving detailed temperature distributions in highly dynamic volcanic emission processes.
Decomposition of a bio-based plastic in soil: CO 2 source partitioning approach
Authors: Guliyev Vusal , Tanunchai Benjawan , Udovenko Maria , Glaser Bruno , Purahong Witoon , Blagodatskaya Evgenia
Published: March 2022

Expanding the use of environmentally friendly materials to protect the environment is one of the key factors in maintaining a sustainable ecological balance. Polybutylene succinate (PBS) and polybutylene succinate-co-adipate (PBSA) are considered the most promising biobased and biodegradable plastics for the future with a high number of applications. We used stable isotope techniques to partition plastic- and soil-originated C in the CO2 released in the course of PBSA plastic decomposition in the soil as dependent on nitrogen availability. Our 90 days laboratory experiment was conducted using a Haplic Chernozem soil from the conventional farming plot of the Global Change Experimental Facility (GCEF), Bad Lauchstädt, Central Germany. The experiment was designed as 4 treatments: two controls (non-amended soil and soil amended with (NH4)2SO4) and two plastic amendments (with (PSN) and without (PS) N). Nitrogen facilitated plastic decomposition by 6 weeks, increased the amount of decomposed plastic by 10% and reduced the priming effect by 26% during the experiment.
Nonlinear time series based forecast modelling of groundwater flooding at karst region in Ireland
Authors: Basu Bidroha , Gill Laurence
Published: March 2022

The intensity and occurrence of groundwater flooding have been found to increase considerably in the past two decades. In general, groundwater flooding occurs over a larger area and for a longer duration, when compared to other types of flooding. The associated damage and disruption caused by groundwater flooding led researchers to focus on the development of groundwater flood forecasting models that can be used for flood risk assessment and development of flood mitigation planning and strategies. This study develops a nonlinear time series model to predict total flooded volume (TFV) in a lowland karst area of Ireland. A Nonlinear Autoregressive model with Exogenous variables (NARX) was developed in the karst region, where rainfall and tidal amplitude had been considered to influence the TFV. The developed NARX model was found to predict TFV with considerable accuracy up to 30 days ahead, with a Kling-Gupta Efficiency (KGE) value of 0.9 or above. The efficiency deteriorates beyond 30 days ahead prediction and becomes 0.81 KGE when the prediction window is 90 days. Comparison of the developed NARX model with a linear time series model in TFV forecast indicates the importance of considering the nonlinear terms while developing the forecasted model. The developed NARX model has the potential to create an early warning system for flooding. The model has further been used to predict freshwater discharge from the inter-tidal spring into the Atlantic Ocean in southern Ireland.
Constraining the formation of the fault-bound Cianzo basin, NW Argentina using low-temperature thermochronology
Authors: van Kooten Willemijn S.M.T. , Sobel Edward R. , del Papa Cecilia , Payrola Patricio , Starck Daniel , Bande Alejandro
Published: March 2022

The transition from the Eastern Cordillera to the Santa Barbara System in NW Argentina is characterized by the inversion of pre-existing Cretaceous and Paleozoic structures. Within this complex fold-and-thrust belt, the Miocene Cianzo basin with its rich sedimentary and structural record tells the tale of Andean reactivation of an extensional fault system and the incorporation of the former Salta rift basin into the orogenic wedge. In the Cretaceous, the intracontinental Salta rift was widely distributed in NW Argentina, with multiple sub-basins radiating from a central high. The Cianzo basin, at that time situated at the northern margin of the ENE-WSW striking Lomas de Olmedo sub-basin, impressively shows the transition from condensed post-rift strata on top of the rift shoulder to thick, proximal syn- and post-rift strata of the Salta Group in the adjacent half-graben. These sediments were buried by up to 3 km of clastics from the approaching orogenic wedge, causing apatite (U-Th-Sm)/He (AHe) and, in part, apatite fission track (AFT) ages to be reset. In the Miocene, deformation reached the Eastern Cordillera, gradually dissecting the foreland basin along pre-existing faults and forming local depocenters such as the Cianzo basin, which is surrounded by inverted normal faults and basement block uplifts. Its unique structural setting and complete sedimentary record provide an excellent natural laboratory to study fold-and-thrust belt formation through reactivation of pre-existing structures. Although the structural and sedimentary characteristics of the Cianzo basin have been studied in detail, low-temperature thermochronology data to quantify deformation processes is lacking. We provide AHe, AFT and zircon (U-Th-Sm)/He (ZHe) cooling ages from 39 samples from the Cianzo basin and adjacent areas. Jurassic ZHe ages from the Aparzo ranges may reflect pre-Salta Group exhumation of the rift shoulder, an event which is also recorded in thick, proximal agglomerates that were shed into restricted depocenters. AHe and AFT data document a Middle-Late Miocene onset of rapid exhumation of the Abra de Zenta, Hornocal and Aparzo ranges that border the Cianzo basin. Furthermore, AHe and AFT ages constrain the sequence of deformation for large folds such as the Cianzo syncline. The new dataset refines the timing of reactivation of pre-existing normal faults that now bound the Cianzo basin and sheds a new light on the propagation of the Eastern Cordillera fold-and-thrust belt in time and space.
Thermal pressurization effect on landslide motion. Analysis with material point method.
Authors: Pinyol Núria , Alvarado Mauricio , Lemus Luis
Published: March 2022

Landslide motion can be affected by the thermal effects resulting from the dissipation in heat of the frictional work generated in shearing bands. This problem was initially addressed for simple landslide geometries which have to be defined a priori. In this context, these analyses assume the motion of a rigid block and the thermal-hydro-mechanical phenomena were solved at basal shearing bands and their vicinity.

Later on, in order to generalize the analysis and to face more complex geometries and features, governing equations were implemented in the material point framework. This numerical method (MPM) is able to model large strains and displacements thanks to the double discretization of the domain by means of a Eulerian computational mesh and Lagrangian material points. A new approach was proposed to deal with the pathological dependence of the frictional work generation and the computational mesh element size. The methodology consists in the definition of computational embedded joints whose thickness is defined as a material parameter. 

The presentation will show the formulation of the thermal pressurization phenomena in MPM. First, the methodology will be evaluated under triaxial conditions and simple landslide geometries using different mesh sizes.

Real cases are later analyzed and modelled in MPM. The first case refers to an incipient landslide induced by a drawdown. The potential risk of acceleration induced by thermal pressurization is analyzed. The non-accelerated behavior observed in the field is explained combining the frictional heating induced weakening with non-linear velocity dependent frictional hardening. The results show that increments of a few degrees of the frictional angle with slide velocity can counteract the heating induced acceleration. 

The second case discussed is a coseismic landslide whose acceleration and large run-out cannot be justified by means of simple strength law unless imposing an extremely and probably unrealistic strain softening.
Upscale and forward transfer of kinetic energy: Impact on giant planetary jet and vortex formation
Authors: Böning Vincent , Wulff Paula , Dietrich Wieland , Christensen Ulrich R. , Wicht Johannes
Published: March 2022

In this study, we analyse the non-linear transfer of kinetic energy in simulations of convection in a 3D rotating shell. Our aim is to understand the role of upscale transfer of kinetic energy and a potential inverse cascade for the formation of zonal jets and large vortices on the giant planets Jupiter and Saturn. We find that the main driving of the jets is associated with upscale transfer directly from the convection scale to the jets. This transfer of energy is mediated by Reynolds stresses, i.e. statistical correlations of velocity components of the small-scale flow.  Intermediate scales are mostly not involved, therefore strictly speaking the jets are not powered by an inverse energy cascade. To a much smaller degree, energy is transferred upscale from the convective scale to large vortices. However, these vortices also receive energy from the jets, likely due to an instability of the jet flow.  Concerning transport in the forward direction, we find as expected that the 3D convective motions transfer energy to the even smaller dissipation scales in a forward cascade.
Who dealt it? Mechanistic modeling of microbial functional types in anaerobic permafrost soils.
Authors: Kaiser Lara , Knoblauch Christian , Beer Christian
Published: March 2022

The release of CH4 and CO2 from thawing permafrost soils will substantially impact the global carbon budget. During anaerobic conditions, these emissions are caused by a complex web of microbes. Depending on their interactions, differing ratios of CH4 to CO2 are produced. In order to predict these emissions, mechanistic modeling of microbial processes is essential but is largely omitted in current climate models. 

We present a new, process-based model for CH4 and CO2 production in anaerobic permafrost soils after thaw, incorporating key microbial functional types. Each microbial functional type is represented by a specific chemical pathway, allowing the calculation of substance utilization and production stoichiometrically for each time step. To the best of our knowledge, this is the first model incorporating a microbial type utilizing alternative electron acceptors, specifically Fe3+. These microbes out-compete acetoclastic methanogens for acetate as long as Fe3+ is sufficiently abundant, thereby suppressing CH4 production via this pathway. In addition, fermentation can be inhibited by the accumulation of its end product acetate, as has been observed in experiments.  We optimize the model parameters against data from an anaerobic permafrost soil incubation experiment over seven years.   
Holocene paleoenvironmental evolution of a playa-lake system in southwestern Iberia (western Mediterranean region)
Authors: Garcia Alix Antonio , Jiménez Moreno Gonzalo , Gázquez Fernando , Monedero-Contreras Ricardo , López-Avilés Alejandro , Jiménez-Espejo Francisco J. , Rodríguez-Rodríguez Miguel , Camuera Jon , Ramos-Román María José , Anderson R. Scott
Published: March 2022

The Mediterranean region is a vulnerable area affected, among other environmental threats, by aridification and desertification processes that can cause soil salinization in areas rich in evaporite deposits. This is especially evident in the evaporite lake systems of southern Iberia, where a combination of both natural and anthropogenic causes gives rise to aridification and land degradation. In this study, we performed a multiproxy analysis (magnetic susceptibility, lithology, bulk organic geochemistry, inorganic geochemistry, and mineralogy) in the sedimentary record of the Laguna de la Ballestera playa-lake in southwestern Iberia in order to reconstruct the environmental evolution of this evaporitic area and potential human impacts during the Holocene. The most humid period registered in the Laguna de la Ballestera record was the Early Holocene with significant catchment runoff and high lake water levels. The lake size, lake level and catchment runoff decreased throughout the Middle and Late Holocene. This aridification trend is especially evident in the Late Holocene when gypsum precipitation enhanced. The highest gypsum contents were registered in the last millennium, especially after 1600 cal yr CE, probably related to important changes in the hydrology of the area, shifting from a (semi) permanent to a temporal and seasonal hydrological regime. These trends represent the local environmental responses to the western Mediterranean climate during the Holocene. The studied proxies did not evidence any potential human impact until the last century, when the catchment runoff and the playa-lake hydroperiod changed, probably related to changes in the land use.
Sea ice dynamics in the Labrador Sea across Heinrich events during MIS 3
Authors: Detlef Henrieka , Mørk Jensen Mads , Glasius Marianne , Pearce Christof
Published: March 2022

The most prominent events of ice-sheet collapse in the recent geological past are so-called Heinrich events observed during millennial-scale climate oscillations of the last glacial period. They are characterized by the dispersal of ice(berg) rafted debris and freshwater across the North Atlantic, with the Hudson Strait suggested as the predominant source region. One potential mechanism triggering iceberg release invokes cryosphere-ocean interactions, where subsurface warming destabilizes the Laurentide ice sheet. In this scenario, the build-up of a subsurface heat reservoir is caused by an extensive sea ice cover in the Labrador Sea in combination with a reduced overturning circulation in the North Atlantic, preventing the release and downward mixing of heat in the water column.

Here we present high-resolution reconstructions of sea ice dynamics in the outer Labrador Sea between 30 ka and 60 ka at IODP Site U1302/03, located on Orphan Knoll. Sea ice reconstructions are based on a suite of sympagic and pelagic biomarkers, including highly branched isoprenoids and sterols. These results suggest a transition from reduced/seasonal to extended/perennial sea ice conditions preceding the onset of iceberg rafting associated with Heinrich event 3, 4, 5, and 5a by a couple of hundred to a thousand years. Our preliminary results thus support the importance of sea ice in the Labrador Sea for triggering Heinrich events. Future results from the same core will have to confirm the timing and extent of subsurface warming and ocean circulation dynamics.  
Towards sustainable agricultural land use in Nepal: The role of irrigation and fertilizer application
Authors: Basukala Amit Kumar , Rasche Livia
Published: March 2022

Rice, wheat, and maize are the most important staple food crops in Nepal. Due to the complex topography and climate of the country, and a lack of agricultural inputs, the productivity of the crops has remained low over the last decades, with only moderate increases in recent years. National production cannot meet the national demand for the three crops, and food imports are necessary to close the gap. Climate and demographic change will most likely exacerbate the problem. It is therefore an objective of the Nepalese government to develop strategies to increase the productivity of the crops permanently and sustainably. A first step in this endeavour is to analyse the existing yield gap and how it may be closed, for which we use the biogeophysical crop model EPIC. We divided Nepal into 3430 homogeneous simulation units (based on climate, altitude, soil, and slope class, overlaid by district boundaries) and simulated current management practices on all units for the years 2000-2014. We then compared the resulting yields to crop production data from the Nepalese Ministry of Agricultural Development and calibrated the model until a good fit was achieved. Subsequently, we estimated maximum potential yields by simulating crop growth without nutrient or water stress, and lastly determined the yield gaps by subtracting the yields under current management practices from the maximum potential yields. We found considerable yield gaps for all three crops 2 t/ha for rice, 4 t/ha for wheat, and 4 t/ha for maize. If we compared the yield gaps between current yields and yields simulated without nutrient stress, but under rainfed conditions, the gaps were smaller, indicating that increasing fertilizer application rates should be the first step in closing the yield gap. However, due to the complicated topography of Nepal, yields and yield gaps of the crops vary considerably between regions, and measures to close the gaps will have to be customized to local conditions. This includes expanding the irrigated area in the lowland Terai regions and valleys in hilly areas where precipitation patterns change and temperature increase under climate change. The findings of this study may support policy-makers in their goal to increase grain production and ensure food security in Nepal.

 

Keywords: yield gap, water management, climate change adaptation

 

 
The Effect of Plasmaspheric Plumes on the Loss of Ring Current Electrons
Authors: Haas Bernhard , Shprits Yuri , Wutzig Michael , Allison Hayley , Wang Dedong
Published: March 2022

Low-energy ring current electrons of up to 50 keV represent a major threat to spacecrafts within the inner magnetosphere since they are one of the main causes of spacecraft surface charging. Furthermore, they can provide a seed population for relativistic radiation belt electrons during geomagnetic storms. In this work, we report the first results of coupling the Versatile Electron Radiation Belt (VERB) code with a fully MLT resolved physics-based plasmasphere model to investigate the loss mechanisms of low energy electrons. Our four dimensional ring current model used in this study includes radial diffusion, convection, and loss due to whistler-mode chorus and hiss waves. The physics-based model of the plasmasphere includes convection of cold plasma and refilling from the ionosphere.
We simulate two storm events from the Van Allen Probes' era and compare results of cold plasma density and electron flux against measurements from the twin Van Allen Probe satellites. Our plasmasphere model is not only capable of predicting the plasmapause location but also the formation of plasmaspheric plumes, where plume whistler mode waves propagate. Including the plume region, which usually has very restricted spatial coverage, allows us to examine the effect of plume whistler mode waves on the loss of ring current electrons during these two events. These plasma boundaries show significant dynamics during the main and recovery phase of storms and are crucial to correctly predict electron loss.
By using the extracted plasma boundaries to determine the spatial extent of different waves species, we find better agreement of electron flux results with measurements, especially during the main phase of storms. We also report on the first ring current simulation results including the loss introduced by spatially localised whistler-wave scattering in plasmaspheric plumes.
Decompression of host-inclusion systems in UHP rocks: insights from observations and models
Authors: Luisier Cindy , Duretz Thibault , Yamato Philippe , Marquardt Julien
Published: March 2022

Polymorphic transformations are key tracers of metamorphic processes, also used to estimate the pressure and temperature conditions reached by a rock. In particular, the quartz-coesite transition is commonly used to define the lower boundary of the ultrahigh-pressure (UHP) metamorphic field. The partial preservation of coesite included in garnets from UHP rocks bring considerable insights into the burial and exhumation mechanisms of the continental crust involved in convergent zone. Coesite was first described in the Western Alps by Chopin[1], in the Dora-Maria whiteschist, one of the most emblematic UHP rock worldwide. Although the partial preservation of coesite inclusions in garnet has long been attributed to the pressure vessel effect, the interrelationship and relative timing between fracturing and retrogression is still contentious.

Here we study the reaction-deformation relationships of coesite inclusions initially enclosed in garnet and transforming into quartz during the decompression process. We combine 2D numerical thermo-mechanical models constrained by pressure-temperature-time (P-T-t) estimates from the Dora-Maira whiteschist. The model accounts for a compressible visco-elasto-plastic rheology including a pressure-density relationship of silica based on thermodynamic data. This allows us to study the effect of reaction-induced volume increase during decompression. Our results capture the typical fracture patterns of the host garnet radiating from retrogressed coesite inclusions and can be used to study the relative role of volume change associated with a change of P-T conditions on the style of deformation during decompression.

The mechanisms of the coesite-quartz transformation and geodynamic implications are presented and validated against geological data. The effect of fluids on the phase transition and the conditions of access of fluids during the transformation are discussed in the light of the results of the thermo-mechanical models.

This study demonstrates the high potential of thermo-mechanical modelling in enhancing our understanding of the processes involved in the formation and evolution of metamorphic minerals.

 

[1]Chopin (1984) Contributions to Mineralogy and Petrology 86, 2, 107-118
Wind veer and wind speed in turbulent Ekman flow
Authors: Ansorge Cedrick , Wurps Hauke
Published: March 2022

The profiles of wind speed and direction in turbulent Ekman flow are formulated based on asymptotic theory and data from direct numerical simulation. The profile of the streamwise component follows the classical viscous, logarithmic and wake scaling. In the outer layer, the velocity component profiles can be described by an Ekman-spiral with adapted boundary conditions that result in a reduction of the spiral-like rotation. The span-wise component poses a conceptual challenge to the channel-flow analogy in the context of asymptotic matching; it exhibits a mixed scaling in the surface layer, but follows outer scaling for most of the outer layer. Viscous stress scales universally across the boundary layer in inner units while the total stress becomes universal as a function of outer height. This implies a mixed scaling for the turbulent stress and eddy viscosity across the inner layer and convergence to a universal scaling as function of the outer height across the outer layer for increasing scale separation vide Reynolds numbers.