bluuebunny/crossref_metadata_2025 huggingface dataset:
Retention of secondary organic aerosols during riming experiments
Authors: Borchers Christine , Dörholt Konstantin , Theis Alexander , Vogel Alexander Lucas , Hoffmann Thorsten
Published: March 2022

The chemical composition of the upper troposphere and lower stratosphere (UTLS) region plays a major role in Earth’s climate. Therefore, it is important to learn more about the transport mechanism of secondary organic aerosols (SOA) and their precursors into the UTLS region. One fast way of transport from the boundary layer to the upper troposphere is the deep convection. Organic vapors and particles, which get dissolved in cloud droplets, can take different pathways if the droplets freeze during the transport to the UTLS. Freezing occurs via different processes, for example riming which describes the freezing of supercooled liquid droplets upon the collision with ice crystals. During the riming the organic compounds could either revolatilise in the mixed zone of clouds or stay in the particles and get washed-out by precipitation or get transported to high altitudes and may revolatilise there if the cloud droplets sublimate. This partitioning between the ice and gas phase is given by the so-called retention coefficients.

Riming experiments in the worldwide unique vertical wind tunnel facility of the Johannes Gutenberg University of Mainz were carried out to derive retention coefficients for pinonoic and pinic acid. Both substances are formed during the monoterpene oxidation and represent SOA constituents.  The simulated conditions were close to those prevailing in the mixed phase zone in convective clouds where riming is the predominant growth mechanism of ice particles. Artificial ice particles were captively floated at their approximate terminal velocity and exposed to a cloud of supercooled droplets containing the substance of interest. The cloud had liquid water contents between 1 and 3 g m-3 and temperatures ranging from -12 to -2 °C representing dry and wet growth conditions. From the concentrations of the substances before and after riming the retention coefficients for pinonic acid or pinic acid were obtained and compared to retention parameterizations available in literature.
Unprecedented stormy seasons and their associated precipitation and wind extremes over Europe
Authors: Owen Laura , Catto Jennifer , Stephenson David , Dunstone Nick
Published: March 2022

Extratropical cyclones and their associated extreme precipitation and winds can have a severe impact on society. These extremes can cause even greater risk when they occur at the same place and time. Studies have investigated stormy seasons and their associated precipitation and wind extremes using observational data. Although these results are limited when looking at the risk of very extreme events, since a large number of samples is needed to get robust estimates. Additionally, it is very difficult for estimates based on observations alone to help us understand the risk of future rare or unprecedented stormy seasons and associated events. Using the UNSEEN method (UNprecedented Simulated Extremes using ENsembles) this risk can be estimated from large ensembles of climate simulations. The Met Office's Global Seasonal forecast system version 5 (GloSea5) model ensembles are evaluated against ERA5 reanalysis data to find out how well they represent storm tracks along with their associated precipitation, wind and compound extremes over Europe. This model has not been evaluated in such a way before and this is needed before the model can be used to estimate the likelihood of unprecedented stormy seasons and associated extremes using the UNSEEN method. We find that although GloSea5 underestimates the numbers of storms over Europe, particularly over the Mediterranean, seasons are found with larger numbers of storms than seen historically. Cyclone composites of precipitation, wind and compound extremes are also compared between ERA5 and GloSea5 ensembles. GloSea5 estimates the spatial pattern and frequency of wind, precipitation and compound extremes around cyclones averaged over their whole lifecycle well. The spatial pattern of extremes around cyclones at maximum intensity is also estimated well but the frequency is underestimated. Given this GloSea5 can be used to investigate the spatial pattern of larger extremes as well as extremes from the most intense storms.
Response of water isotopes in precipitation to a collapse of the West Antarctic Ice Sheet in high resolution simulations with the Weather Research and Forecasting and Community Atmosphere Models
Authors: Duetsch Marina , Blossey Peter N. , Pauling Andrew G. , Steig Eric J.
Published: March 2022

The West Antarctic Ice Sheet (WAIS) may have collapsed during the last interglacial period, between 132,000 and 116,000 years ago. The changes in topography resulting from WAIS collapse would be accompanied by significant changes in Antarctic surface climate, atmospheric circulation and ocean surface conditions. Evidence of these changes may be recorded in water-isotope ratios in precipitation archived in the ice. We conducted high-resolution simulations with an isotope-enabled version of the Weather Research and Forecasting Model over Antarctica, using boundary conditions provided by climate-model simulations with both present-day and lowered WAIS topography. The results show that while there is significant spatial variability, WAIS collapse would cause detectable isotopic changes at several locations where ice-core records have been obtained or could be obtained in the future. The most robust signals include lower δ18O at Mount Moulton Blue Ice Area and higher δ18O at SkyTrain Ice Rise in West Antarctica, and higher deuterium excess at Hercules Dome, East Antarctica. A combination of records from multiple sites would provide the strongest constraint on the timing and magnitude of past WAIS collapse.
The 14 December 2021, Mw 7.4 Flores Earthquake: Review of the hypocenter relocation, slip distribution, coulomb stress, and seismic hazard
Authors: Rohadi Supriyanto , Prakoso Tio Azhar , Yatimantoro Tatok , Rahman Aditya , Sunardi Bambang , Adimarta Agustya , Riama Nelly Florida , Adi Suko Prayitno , Karnawati Dwikorita
Published: March 2022

A major earthquakes struck the north of Flores island, in Nusa Tenggara Timur, Indonesia, on 14  December 2021 at 10:20:22 local time, the hypocenter is 7.59°S, 122.26°E, depth 12.0 km, with moment magnitude Mw 7.4. The faulting orientation of the mainshock, fault plane was strike = 290°, dip = 89°, and rake = 177°, and the auxiliary plane was strike = 21°, dip = 87°, and rake = 1°, respectively, is possibly related to thrust fault in the sea. Focal mechanism solutions for the earthquakes indicate rupture occurred thrust fault with large dip angle. The mainshock was followed by low aftershocks productivity may due to homogeneous faulting systems and relatively uniform stress state in that region. We analyze aftershock hypocenter relocation and gravity anomaly, slip distribution, coulomb stress and seismic hazard (PSHA) to investigate the earthquake characteristics and seismic hazard analysis. The distribution of hypocenter relocations show that aftershock ruptured distribute between two block of high gravity anomaly, its indicate that it was not the new fault. The inversion of the source model shows several time periods of energy release with three main peaks. These temporal rupture suggest repetition of a large scale slip on the large asperity. The models of coulomb stress indicate that static stress transfer due to the Mw 7.4 earthquake is suitable with aftershock spatial distribution. We compute the probabilistic seismic hazard assessment in the Flores region for Earthquake mitigation
Mapping and quantifying groundwater fluxes and origin at the land-sea interface using temperature, chloride and stable isotopes: An example from Königshafen, Sylt
Authors: Gilfedder Benjamin , Riedel Ramona , List Joana , Böttcher Michael , Frei Sven
Published: March 2022

Beach faces form the interface between terrestrial and marine systems. They act as a reactive zone between these two compartments, transporting and biogeochemically modifying terrestrially sourced chemical constituents such as nutrients, pollutants and carbon towards the sea. This interface is referred to as the subterranean estuary. The subterranean estuary is important on global scales for modifying and processing dissolved and particulate matter sourced from the sea as it cycles through the beach sediments. Re-circulation of sea water through beach sediments is largely driven by tidal pumping and pressure gradients caused by tides, wave setup, and storm events that pile sea water up on the beach face. In contrast, terrestrial groundwater systems provide a source of low salinity and often nutrient rich water to the coastal zone. Mixing between these water sources is complicated by catchment morphology, variable density flow caused by saline sea water lying above and below the fresh terrestrial groundwater. Thus tracing water and nutrients fluxes through the subterranean estuary is not trivial. In this work we use a combination of temperature measurements and heat modelling to estimate water fluxes through the subterranean estuary and pore water stable isotopes and chemistry to infer the origin of this discharge in the Königshafen, on Sylt Island, Northern Germany. The results show that flow paths are complex, with dune morphology influencing the focal point for fresh groundwater discharge. Seaward, saline and brackish discharge occurs into the tidal creek draining the bay. The complexity of heat transport modelling in the coastal zone depends on the boundary conditions, with very complex boundaries requiring more complex modelling structures (e.g. steady state vs. non steady state). Overall temperature measurements and heat modelling combined with pore water chemistry show potential to understand water and chemical exchange through the subterranean estuary and thus help to understand water and material fluxes at the terrestrial-ocean interface.
About the character of variation of 90Sr concentration in plants within elementary landscape geochemical system
Authors: Korobova Elena , Baranchukov Vladimir , Dolgushin Denis , Tarasov Oleg , Mikhailovskaya Lyudmila
Published: March 2022

A detailed study of 90Sr distribution in the overground vegetation cover within an elementary landscape geochemical system (top-slope-closing depression, ELGS) was performed in several forested and meadow test sites located in the Eastern Urals Radioactive Trace highly contaminated with this technogenic radionuclide during its release in the Kyshtym accident in 1957 (INES level 6). After selecting the suitable test sites, they were crossed by several lateral profiles along which relative altitude with a step of 1 m and precision of 1 cm was measured using theodolite Boif-DJD10. Averaged plant samples were taken at each point within a standard steel ring (14 cm diameter) later separated into the groups of cereals, legumes and other different herbs. Particular species were also collected if present at no less than seven consequent points. Strontium-90 activity was measured by the portable complex ”Colibri” (SKS-08P) developed in the Kurchatov Institute (Potapov et al., 2021). It allowed the measurement of radionuclide activity in field conditions. The determination error did not exceed 15%. Analysis of data obtained revealed the ordered variation of 90Sr in all groups of plants. This order was presented by the cyclic (periodic) change of 90Sr activity downslope without definite radionuclide accumulation at the foot of the slope and in depression as usually expected. A similar cyclic pattern was found for 137Cs variation in moss cover studied in the Chernobyl zone (Dolgushin & Korobova, 2021). We consider it reflects peculiarities of water migration in the soil-plant system at the ELGS scale. Specific 90Sr activity in forest grasses correlated with biomass volume while plant groups and species with the different activity of radionuclides significantly differed in 90Sr variation amplitude and its maximum values. The revealed features of variation likely reflect the peculiarities of 90Sr water migration in soils, the structure of root system, and the plants' ecological demands, such as their hydrophilicity.

References

Potapov, V.N., Ivanov, O.P., Luk’yanov, V.V. et al. Portable β-Spectrometer for 90Sr Activity Field-Measurements in Radioecology and Rehabilitation of Nuclear Energy Facilities. At Energy 129, 155–162 (2021). https://doi.org/10.1007/s10512-021-00728-5

Dolgushin, D. and Korobova, E.: New data on the character of 137Cs lateral and vertical migration in soil-litter-moss cover within undisturbed elementary landscape geochemical systems on the test site in the Chernobyl abandoned zone, Russia, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7691, https://doi.org/10.5194/egusphere-egu21-7691, 2021.
Co-seismic Landslide Susceptibility Modelling Based on the Fibre Bundle Model
Authors: Chen Yuanjing , van den Bout Bastian , van Westen Cees , Lombardo Luigi
Published: March 2022

Co-seismic landslides are triggered by strong ground shaking in mountainous areas, resulting in threats to human activity and infrastructure. Co-seismic landslide susceptibility assessment plays a vital role in disaster prevention and mitigation. However, existing physical models for susceptibility assessment do not involve the dynamic nature of seismicity and the progressive processes of landslide initiation. The challenge of linking the development of internal cracks caused by dynamic seismic loading with the process of localized failure from abrupt mass movement will be addressed by a new physically based model that bridges the limit-equilibrium stability analysis with the fibre bundle model (FBM), which the FBM is a mathematical framework to simulate the highly nonlinear behaviour of the progressive damage and breakdown of disordered media statistically. Each hillslope in a catchment is depicted as an assembly of virtual bundles of fibres that represented the soil columns. The vibrating seismic load exerted on the mechanical connections causes the fibres to break progressively until restraining forces are exceeded. Since cracks occur at the interface of different soil layers, load redistribution occurs from the broken column to its neighbours through intact mechanical linkages, resulting in a new mechanical state. When the ground columns lose their balance, a load-bearing column can liquefy and trigger a landslide which could spread downstream. primary purpose of this study is to develop a semi-physical model for simulating the earthquake-induced landslides by incorporating earthquake time histories into a spatially distributed slope stability method on the basis of the FBM to represent the localized failure occurring prior to landslide release or after the ground shaking. The study has four specific objectives: (1) Development of a model framework assembled with the limit-equilibrium analysis and FBM for seismic effect simulation on hillslopes; (2) Development of an efficient regional method for physically based simulation of co-seismic slope instability; (3) Derive a method for predicting the increase in susceptibility to rainfall-induced landslides after seismic shaking, taking into account the soil healing process; (4) Determine the effect of vertical variation in soil strength parameters and groundwater table depth on the fibre bundle model by implementing a multi-layer approach. The proposed model framework linking limit-equilibrium stability analysis and fibre bundle model should sufficiently consider the dynamic characteristics of seismicity and progressive slope failure processes of landslide triggering.
Mineral inclusions in detrital garnet – A complementary tool in ultrahigh-pressure research
Authors: Schönig Jan , von Eynatten Hilmar , Meinhold Guido , Lünsdorf N. Keno , Baldwin Suzanne L.
Published: March 2022

Documenting ultrahigh-pressure (UHP) metamorphism in the geologic record is a key for understanding the evolution of plate tectonics on Earth. Characteristic UHP minerals like coesite and diamond that form during deep subduction are frequently replaced by their low-pressure polymorphs during exhumation. However, when entrapped as inclusions in resistant host minerals like garnet, coesite and diamond are shielded from external metamorphic fluids and may be preserved. Finding evidence for deep subduction processes in host garnets of large volumes of (partially) re-equilibrated crystalline rocks is challenging, time consuming, and often hampered by poor outcrop conditions due to weathering and soil formation. In contrast, by analyzing detrital garnet, natural processes such as erosion and sedimentary transport can sample garnet grains sourced from fresh as well as altered crystalline rocks located in the drainage area, enabling large crustal volumes to be screened using a comparatively low number of samples. Case-studies from the Western Gneiss Region of Norway (Schönig et al. 2018), the Saxonian Erzgebirge of Germany (Schönig et al. 2019, 2020), and the (U)HP terrane of eastern Papua New Guinea (Baldwin et al. 2021) demonstrate mineral inclusion analysis of detrital garnet to be a complementary and efficient tool in UHP research. This contribution gives a synopsis of the main findings from the three spatially, chronologically, and tectonically distinct UHP terranes studied, putting emphasis on the spatial extent of UHP metamorphism and lithologies involved.
A Revised Collection of Sunspot Group Numbers: Context and Future Improvements
Authors: Carrasco Víctor
Published: March 2022

Rudolf Wolf, first director of the Zürich Observatory around mid-19th century, recovered a large number of sunspot observations made by astronomers several solar cycles back. Based on that database, he defined the relative sunspot number from the number of sunspot groups and individual sunspots. He extended his daily and monthly series until 1749, whereas his yearly series to 1700 (Clette et al. 2014). Nowadays, the World Data Center Sunspot Index and Long-term Solar Observations is the responsible to maintain this sunspot number index. At the end of the 20th century, Hoyt and Schatten (1998) compiled more sunspot observations made by astronomers since the beginning of the 17th century. Thus, they created the group sunspot number index from the number of sunspot groups. Unlike the relative sunspot number, their series starts in 1610.

More recently, several works have detected some problems both in these two indices and the databases. For example, Vaquero et al. (2016) published a revised collection of sunspot group numbers correcting some of the mistakes found in the Hoyt and Schatten database, in addition to incorporate other unknown sunspot records. Currently, there is an ongoing global effort to improve the weakness of the database and recalibrate the indices. Some remarkable improvements to be carried out in future versions of the sunspot number databases have been made regarding the earliest sunspot observations recorded by astronomers such as Galileo and Scheiner, inter alia. Then, corrections of significant mistakes detected in the sunspot counting assigned to these observers in the existing databases are proposed as well as the incorporation of telescopic sunspot records made by the earliest observers not included in these databases.

The sunspot number series is the index including the longest direct solar observation set to study the long-term solar activity evolution and its influence on the Earth. Therefore, we need that the databases, in which these indices are based, are free of problematic observations and, moreover, to improve their observational coverage before mid-19th century. Thus, we will understand better past, present and future solar activity.

References

Clette, F., Svalgaard, L., Vaquero, J.M., Cliver, E.W.: 2014, Revisiting the Sunspot Number. A 400-Year Perspective on the Solar Cycle, SSRv 186, 35. DOI: 10.1007/s11214-014-0074-2.

Hoyt, D.V., Schatten, K.H.: 1998, Group sunspot numbers: a new solar activity reconstruction. Solar Phys. 179, 189. DOI: 10.1023/A:1005007527816.

Vaquero, J.M., Svalgaard, L., Carrasco, V.M.S., Clette, F., Lefèvre, L., Gallego, M.C., Arlt, R., Aparicio, A.J.P., Richard, J.-G., Howe, R.: 2016, A Revised Collection of Sunspot Group Numbers, Sol. Phys. 291, 3061. DOI: 10.1007/s11207-016-0982-2.
Isotopic and geochemical studies in the Upper Ganga Basin, Uttarakhand, India: Implications on Dissolved Inorganic Carbon systematics
Authors: Chatterjee Nikitasha , Tiwari Sameer K. , Gupta Anil K. , Sharma Kanishak
Published: March 2022

In the recent scenario of global warming, the release of organic and inorganic carbon from the melting glaciers has been a subject of scientific research since it can have a pronounced effect on the riverine carbon cycle and primary productivity. Apart from being one of the largest Himalayan glaciers, Gangotri glacier provides water to the Bhagirathi River (Ganga River) which is the most important perennial river in India in terms of economy and livelihood. In the last decade, the melting and recession of Gangotri glacier have increased significantly leading to the formation of glacial lakes and debris-covered areas. As a result, primary productivity and microbial activity have increased in the subglacial areas which release a great amount of soil CO2 that has not been documented previously in the literature. In the present study, the Bhagirathi River, which is the proglacial melt-stream of the Gangotri glacier has been sampled during the Post-monsoon period. A total of 27 samples including river, groundwater, geothermal spring, and reservoir were collected and have been analyzed for pH, surface temperature, Electrical conductivity (EC), major ions, and stable isotopes of carbon. From the study of major ion abundance patterns and mixing ratios, it has been inferred that carbonate weathering is predominant in the basin, though the major rock type of the area are silicates. The (HCO3- ≈ Dissolved Inorganic Carbon, DIC) values of river water show no correlation with altitude (mean = 42.8 mg/L), while δ13C values show a decreasing trend with a decrease in altitude, with an overall range between -10 and - 5‰. As altitude decreases, organic matter activity increases, and thus more CO2 is washed out from the Soil Organic Matter (SOM), which makes the δ13C values of the river depleted. The δ13C of groundwater (mean = -11.8‰) and reservoir water (mean = -9.4‰) are depleted than river water due to mixing of soil carbon in them, and δ13C of geothermal spring water (mean = -3.6‰), shows enriched values since these are places of active CO2 degassing. The source of DIC in the river water is mainly carbonate weathering in the upstream part and soil CO2 in the downstream part of the study area. Quantifying pCO2 values of the river water and calculating carbon flux from the river would provide important information on whether the Bhagirathi River is acting as a carbon source or sink to the atmosphere.
An Integrated Microscopy And Spectroscopy Approach For The Characterization Of Air Particulate Matter
Authors: Giardino Matteo , Tiano Andrea , Baietto Oliviero , Janner Davide , Bellopede Rossana
Published: March 2022

As the main responsible of pollution, particulate matter (PM) in big cities and industrial sites greatly affects the life quality of an ever-growing number of people all over the world. That situation drives the strong effort for continuous PM monitoring by governmental and environmental protection agencies. Despite great attention to such air quality control, the analysis of particulate is often limited to the study of size distribution and elemental composition giving only few information on the pollutant sources of origin (source apportionment). Information about such sources could assist in the development of strategies towards the reduction of pollutant emissions.

In this framework, we report a novel integrated approach for the qualitative and quantitative analysis of air particulate. The developed method leverages on the integration of different analytical techniques on PM samples such as Scanning Electron Microscopy (SEM), Raman Spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR). The proposed protocol aims both at identifying the main constituents of air particulate identifying at the same time its sources (car wheel, combustion, asphalt, car brake, etc…).

The SEM analysis provides information on the size distribution and elemental composition of the particles, whereas the Raman and FTIR spectroscopy allow for the identification of the actual components. By comparing the results of the analysis with a database of spectra obtained from known samples, PM particles can be associated with a probable source.

Finally, a mapping strategy of air sampling filters for the rough quantification of each component of the particulate via Raman and FTIR spectroscopy will be presented.
The EnVision Mission to Venus
Authors: Widemann Thomas , Ghail Richard , Wilson Colin , Titov Dmitri , Straume Anne Grete , Ocampo Adriana , Bocanegra-Bahamon Tatiana , Bruzzone Lorenzo , Campbell Bruce , Carter Lynn , Dumoulin Caroline , Gilli Gabriella , Helbert Jörn , Hensley Scott , Kiefer Walter , Marcq Emmanuel , Mason Philippa , Moreira Alberto , Vandaele Ann Carine
Published: March 2022

On June 10, 2021, the European Space Agency (ESA) announced the selection of EnVision as its newest medium-class science mission. EnVision's overarching science questions are to explore the full range of geoscientific processes operating on Venus [1, 2]. It will investigate Venus from its inner core to its atmosphere at an unprecedented scale of resolution, characterising in particular core and mantle structure, signs of past geologic processes, and looking for evidence of past liquid water. Recent modeling studies strongly suggest that the evolution of the atmosphere and interior of Venus are coupled, emphasizing the need to study the atmosphere, surface, and interior of Venus as a system. The nominal science phase of the mission will last six Venus sidereal days (four Earth years). EnVision will downlink 210 Tbits of science data, using a Ka-/X-band comms system with a 2.5 m diameter fixed high-gain antenna. As a key partner in the mission, NASA provides the Synthetic Aperture Radar, VenSAR.

The EnVision payload consists of five instruments provided by European and US institutions. The five instruments comprise a comprehensive measurement suite spanning infrared, ultraviolet-visible, microwave and high frequency wavelengths. This suite is complemented by the Radio Science investigation exploiting the spacecraft TT&C system. All instruments in the payload have substantial heritage and robust margins relative to the requirements with designs suitable for operation in the Venus environment. This suite of instruments was chosen to meet the broad spectrum of measurement requirements needed to support EnVision science investigations. Two parallel competitive industrial studies will continue in the Definition Phase B1, to complete trade-offs, consolidate requirements and interfaces, produce system specifications,  support development of the science operations, calibration strategies, science products definition under the responsibility of the Future Missions Department (SCI-F) and under the authority of the EnVision Study Manager until Mission Adoption Review (MAR) scheduled in 2024. 

[1] ESA's EnVision Assessment Study Report: sci.esa.int/web/cosmic-vision/envision-assessment-study-report-yellow-book. [2] EnVision mission website: www.envisionvenus.eu.
A simplified microphysics model to assess the impact of gravity waves on homogeneous ice nucleation in the tropical tropopause layer 
Authors: Corcos Milena , Hertzog Albert , Plougonven Riwal , Podglajen Aurélien
Published: March 2022

We present first results aiming at understanding the impact of gravity waves on homogeneous ice nucleation in a simplified microphysics set-up. We use a 1D model of homogeneous ice nucleation, growth, sedimentation, and mixing due to wind shear. This model describes the evolution of ice crystals number and mass with 36 bins of size, after freezing on particles of ammonium sulfate. 420 supersaturated air parcels of 20m thickness and 200m length, distributed in a 7 columns grid, are simulated simultaneously, allowing exchanges of ice crystals between the air masses by sedimentation and horizontal mixing.

 

A first simple set-up represents the large-scale ascending motion of air parcels in the tropics, with a vertical speed of 0.5 mm/s. Air parcels follow a typical tropical temperature profile, between 16400 and 17700 m of altitude. The maximum of nucleated ice crystals is found just below the cold point and nucleation occurs in a layer of 400m, whereas sedimented ice crystals are found down to the bottom of the columns of air masses, showing that the width of cirrus clouds is different from the nucleation layer. The majority of nucleated ice crystals is small enough to be carried up with the air parcels. Yet the fall streaks of a few bigger crystals deplete the humidity of air parcels beneath, preventing new nucleation events from happening. We find that more than half of the total ice mass in air parcels is from the sedimented crystals only, even though they represent less than a third of the number of crystals counted in our system. These few crystals are responsible for more than half of the diminution of the humidity within the air parcels.

 

A second experiment is designed to take into account smaller scale perturbations induced by gravity waves, by coupling the microphysics model with lagrangian temperature measurements from superpressure balloons of the first Stratéole-2 campaign. Gravity waves are found to create more nucleation events, in time and at all altitude levels of our experiment, expanding the nucleation layer up to one kilometer. The larger cooling rates create more small crystals, but the growth of ice is slowed down by the waves’s warming phases and the decreased humidity from more nucleation events. Furthermore, gravity waves prevent the biggest ice crystals from appearing. Last, the addition of gravity waves removes on average less humidity from the air parcels than the sedimentation of ice crystals nucleated during the slow unperturbed ascent.
Analytical Modelling of Curved Cylindrical Flux Ropes
Authors: Weiss Andreas , Nieves-Chinchilla Teresa , Möstl Christian , Reiss Martin , Hinterreiter Jürgen , Amerstorfer Tanja , Bailey Rachel
Published: March 2022

We present our most recent results for an analytical flux rope model that includes the effects of curvature and torsion on the magnetic field. Our analytical model consists of a cylindrical flux rope that can be bent or twisted in any manner under the condition of axial and poloidal flux conservation. We can furthermore configure our model to exhibit any arbitrary radial twist distribution but we do not necessarily assume the structure to be force-free. The approach can serve as a first stepping point to better model the deformations of ICME flux ropes that are expected to occur due to longitudinal velocity differentials in the solar wind. It is briefly discussed how this model can be implemented in real-world simulations and how it can be extended to non-cylindrical shapes.
Acclimation of leaf photosynthesis in mature Beech and Spruce during 5 years of repeated summer drought
Authors: Hikino Kyohsuke , Gebhardt Timo , Hesse Benjamin D. , Hafner Benjamin D. , Häberle Karl-Heinz , Grams Thorsten E.E.
Published: March 2022

Forest ecosystems have been globally experiencing drought events with increasing duration and frequency in the last decades. Under these circumstances, perennial trees must adjust to long-term water-limiting conditions for their survival. However, the acclimation ability of mature trees is still poorly understood.

This contribution presents observations from a 5-year summer throughfall-exclusion experiment on mature European beech (Fagus sylvatica) and Norway spruce (Picea abies) in southern Germany (Kranzberg forest roof experiment (KROOF)). Precipitation throughfall was completely excluded from spring to late fall (i.e. March to November) between 2014 and 2018.

In the first two drought years, predawn leaf water potential of both species significantly decreased as low as -1.8 MPa, leading to a significant reduction in CO2 assimilation rates and stomatal conductance, in particular in spruce with a reduction of up to 85% compared to controls. However, although the soil water content was similar throughout the measurement periods, this decrease in predawn leaf water potential was diminished in the fourth and fifth year of the drought treatment, leading to a parallel increase in leaf photosynthesis. Especially, CO2 assimilation rates and stomatal conductance of beech that were reduced by 40% in the second and third drought year, showed similar values to the controls in the fourth and fifth drought year.

Thus, both species seem to have ability to attenuate water stress under long-term drought. While drought-stressed spruce trees significantly reduced their total leaf area two years after the start of the drought treatment, leading to more available water per leaf area, beech trees seem to have maintained their total leaf area even under long-term drought. These observed drought responses and acclimation strategies of both species are discussed taking belowground perspectives into account.
Ionospheric perturbations related to seismicity and volcanic eruptions inferred from VLF/LF electric field measurements 
Authors: Eichelberger Hans U. , Schwingenschuh Konrad , Boudjada Mohammed Y. , Besser Bruno P. , Wolbang Daniel , Solovieva Maria , Biagi Pier F. , Stachel Manfred , Aydogar Özer , Schirninger Christoph , Muck Cosima , Grill Claudia , Jernej Irmgard
Published: March 2022

In this study we investigate electric field perturbations from sub-ionospheric VLF/LF paths which cross seismic and volcanic active areas. We use waveguide cavity radio links from the transmitters TBB (26.70 kHz, Bafa, Turkey) and ITS (45.90 kHz, Niscemi, Sicily, Italy) to the seismo-electromagnetic receiver facility GRZ (Graz, Austria). The continuous real-time amplitude and phase measurements have a temporal resolution of 1 sec, events are analyzed for the period 2020-2021. Of high interest in this time span are paroxysms of the stratovolcano Mt. Etna, Sicily, Italy. We show electric field amplitude variations which could be related to atmospheric waves, occurred at the active crater and propagated up to the lower ionosphere. This corresponds to vertical coupling processes from the ground to the E-region, the upper waveguide boundary during night-time. Ionospheric variations possibly related to earthquakes are discussed for events along the TBB-GRZ path, assumed is an area given by the so-called effective precursor manifestation zone [1,2]. The findings indicate statistical relations between electric field amplitude variations of the ITS-GRZ path in the VLF/LF sub-ionospheric waveguide and high volcanic activity of Etna. For earthquakes multi-parametric observations shall be taken into account to diagnose physical processes related to the events. In summary, VLF/LF investigations in a network together with automated data processing can be an essential component of natural hazards characterization.

References:

[1] Dobrovolsky, I.P., Zubkov, S.I., and Miachkin, V.I., Estimation of the size of earthquake preparation zones, PAGEOPH 117, 1025–1044, 1979. https://doi.org/10.1007/BF00876083

[2] Bowman, D.D., Ouillon, G., Sammis, C.G., Sornette, A., and Sornette, D., An observational test of the critical earthquake concept, JGR Solid Earth, 103, B10, 24359-24372, 1998. https://doi.org/10.1029/98JB00792
Offline models for statistical post-processing of surface weather variables
Authors: Ben Bouallegue Zied , Cooper Fenwick , Chantry Matthew
Published: March 2022

Statistical post-processing based on machine learning (ML) methods aims to capture systematic forecasts errors, relying on information from various predictors. We explore the exclusive use of “offline” predictors for the bias correction and uncertainty estimation of 2m temperature and 10 m wind speed forecasts. Offline predictors are defined as predictors available before the start of the forecast-of-the-day. Offline predictors encompass model characteristics such as the model orography and the model vegetation cover as well as spatio-temporal markers such as the day of the year, the time of the day and the latitude. The resulting offline models are particularly simple to implement as no time-critical operations are involved. The benefits of offline models and performance compared with more complex approaches will be discussed. 
Studies on Space Climate Made in the University of Extremadura (Spain)
Authors: Carrasco Víctor M.S. , Aparicio Alejandro J.P. , Nogales José M. , Bravo-Paredes Nieves , Tovar Irene , Gallego Maricruz , Vaquero José M.
Published: March 2022

Our research group has carried out several studies on space climate in the past. One of our lines of work is the recovery and analysis of the catalogues including historical sunspot observations. We have already published in digital version some sunspot catalogues made in observatories, for example, of the Iberian Peninsula (Aparicio et al. 2018). Recently, we have also digitized the catalogue from the sunspot observations made in the Stonyhurst College Observatory for 1921 – 1935 (Carrasco et al. 2021) and completed the first step for the publication of the Sacramento Peak Observatory sunspot catalogue (1947 – 2004) (Carrasco et al. 2020). Currently, we are analyzing the sunspot observations from drawings made in Boulder (U.S.A) for the period 1966 – 1992 to create a sunspot group catalogue including that information. Furthermore, we have also analyzed long-term observation series made by individual astronomers. Two examples of this kind of studies can be the analysis of the sunspot observations made by David Hadden during the period 1890 – 1931 (Carrasco et al. 2013) and those made by Eric Strach for 1969 – 2008 (Carrasco et al. 2019). Nowadays, in collaboration with other Italian research group, we are studying all the sunspot drawings made by Father Angelo Secchi in the second half of the 19th century. We are constructing the Wolf number, group number and the area series from these drawings. As future work, our objective is to publish a sunspot group catalogue from these observations.

References

Aparicio, A.J.P., Lefèvre, L., Gallego, M.C., Vaquero, J.M., Clette, F., Bravo-Paredes, N., Galaviz, P., Bautista, M.L.: 2018, A Sunspot Catalog for the Period 1952 – 1986 from Observations Made at the Madrid Astronomical Observatory, Solar Physics 293, 164.

Carrasco, V.M.S., Vaquero, J.M., Gallego, M.C., Trigo, R.M.: 2013, Forty two years counting spots: Solar observations by D.E. Hadden during 1890–1931 revisited. New Astronomy 25, 95.

Carrasco, V.M.S, Vaquero, J.M., Olmo-Mateos, V.M.: 2019, Eric Strach: Four Decades of Detailed Synoptic Solar Observations (1969‐2008), Space Weather 17, 796.

Carrasco, V.M.S., Pevtsov, A.A., Nogales, J.M., Vaquero, J.M.: 2020, The Sunspot Drawing Collection of the National Solar Observatory at Sacramento Peak (1947–2004), Solar Physics 296, 3.

Carrasco, V.M.S., Muñoz-Jaramillo, A., Nogales, J.M., Gallego, M.C., Vaquero, J.M.: 2021, Sunspot Catalog (1921–1935) and Area Series (1886–1940) from the Stonyhurst College Observatory, Astrophysical Journal Supplement Series 256, 38.
Effect of warming on β-glucosidase activity and root exudates depends on soil moisture: Combining Zymography with glucose imaging and enzyme kinetic
Authors: Hosseini Seyed Sajjad , Sultan Sayeda Rabia , Rashtbari Mehdi , Lakzian Amir , Razavi Bahar S.
Published: March 2022

Temperature and soil moisture strongly affect plant root exudates and enzyme activities. Global warming may stimulate root exudation and enzyme activities while drought can drop releasing of root exudates and inhibit enzyme activities. However, how the interaction of warming and drought regulate these processes in the rhizosphere is poorly known. To clarify these interactions, wheat plants were grown for one month at 20 and 30 ºC in drought (30% WHC) and optimum (70% WHC) condition. To investigate the pattern of root exudates releasing and enzyme activities, we combined β-glucosidase zymography with glucose imaging and enzyme kinetic.

Drought significantly decreased hotspots of glucose in compare to optimum condition at both temperatures. Releasing of glucose by wheat at 30 ºC was 53% lower than at 20 ºC in optimum condition. Hotspots of β-glucosidase activity in drought was 52% and 37.7% lower than in optimum at 20 and 30 ºC, respectively. β-glucosidase hotspot at 30 ºC was 12.2% lower than at 20 ºC in optimum condition. The results of enzyme kinetic (Vmax and Km) showed that drought decreased β-glucosidase activity in compare to optimum condition at both temperatures. β-glucosidase activity at 30 ºC was 2 times higher that at 20 ºC in optimum condition. On the contrary, it was 56% lower than at 20 ºC in drought condition. Drought increased Km at 20 ºC while decreased it at 30 ºC in compare to optimum condition. The affinity of β-glucosidase for substrates in optimum condition was not affected by temperature. Km value at 30 ºC was lower than at 20 ºC in drought condition. According to these results, the warming in optimum condition (high labile carbon availability) decreased enzyme production and substrates release and did not change the affinity of enzyme for substrates. While warming in drought condition (low labile carbon availability) produced an enzyme pool with high efficiencies and did not change enzyme production and substrates release.
Three-dimensional simulation of biochemical processes in inland waters
Authors: Gladskikh Daria , Mortikov Evgeny , Stepanenko Victor
Published: March 2022

Within the framework of this study, a three-dimensional numerical model of biochemical processes was developed, which complements the model of thermohydrodynamics of the lake. The proposed model includes equations to describe the transport, diffusion, and reactions of dissolved gases. To compare the calculations with the measurement data, the bottom topography and atmospheric forcing were taken into account. For the flux of short-wave radiation, the parameterization of the extinction coefficient was implemented. To assess the contribution of density stratification and velocity shear to the processes of small-scale turbulence in lakes, a modification of the standard two-parameter k-epsilon closure was proposed. The basis of the parameterization is the model that reproduces mutual transformation of the kinetic and potential energy of turbulent pulsations.

The work was supported by the RFBR (20-05-00776), by Moscow Center of Fundamental and Applied Mathematics (agreement with the Ministry of Science and Higher Education 075-15-2019-1621), and by grant of the RF President’s Grant for Young Scientists (MD-1850.2020.5)
Detailed Structure of the South American Cratons Using Waveform Tomography
Authors: Chagas de Melo Bruna , Lebedev Sergei , Celli Nicolas , Assumpção Marcelo
Published: March 2022

South America presents a diverse tectonic set-up, with an active subduction margin on the western border and a stable continental interior to the east. In the ancient stable part, two main cratonic domains can be separated. The Amazonian, consolidated in Archean-Paleoproterozoic times, and the Brasiliano, marked by Neoproterozoic events related to the West Gondwana assembly. In each domain, geology and geophysical methods separate different cratonic nuclei. However, some nuclei's detailed lateral and vertical extent and even existence are debated.

In seismic tomography, we can define regions of cratonic lithosphere due to the shear wave sensitivity to temperature and composition. However, until recently, seismic data sampling in South America was highly scarce and uneven. Here, we assembled all freely available seismic data globally, with the addition of the FAPESP "3-Basins Thematic Project" temporary network. After selecting all paths crossing the hemisphere centred at South America and performing an automatic outlier rejection, we obtain a massive dataset of ~1 million waveform fits, constraining our final model.

We compute a new S-velocity tomographic model of the upper mantle of South America and surrounding oceans using the Automated Multimode Inversion of surface, S- and multiple S-waves. The increase in the data coverage of the model combined with the optimized tuning of the inversion parameters on the continent allows us to identify for the first time the fine details present in the cratonic structure. We observe that regions of thinner lithosphere inside cratons correspond to areas of rifting in previous tectonic cycles. Inside the boundaries of the Amazon craton, we image two cratonic blocks, separated by the Amazon basin. In this area, an aborted rift system preceded the formation of the Amazon basin in the Neoproterozoic, and rift reactivation occurred with the break-up of Pangea in the Mesozoic. Similarly, in the São Francisco Craton, we image a significantly thinner lithosphere in the Paramirim Aulacogen area, a Paleoproterozoic intracontinental rift system. These observations show that the continental lithospheric topography is closely related to upper mantle dynamic processes. We also image high-velocity lithospheric blocks under sedimentary basins. East of the Amazon craton, we image a high-velocity anomaly beneath the Parnaíba block, and under the Paraná basin the fragmented Paranapanema block lithosphere. Finally, by imaging the boundary of the cratonic units in detail, we can observe that magmatic events and large igneous provinces are distributed around the thick roots of the cratons, where the lithosphere is thinner.
Revised Modular Model of Mercury’s Magnetospheric Magnetic Field
Authors: Pump Kristin , Heyner Daniel , Plaschke Ferdinand
Published: March 2022

Mercury is the smallest an innermost planet of our solar system and has a dipole-dominated internal magnetic field that is relatively weak, very axisymmetric and significantly offset towards north. Through the interaction with the solar wind, this field leads to a magnetosphere. Compared to the magnetosphere of Earth, Mercury’s magnetosphere is smaller and more dynamic. To understand the magnetospheric structures and processes we use in-situ MESSENGER data to develop a semi-empiric model, which can explain the observations and help to improve the mission planning for the BepiColombo mission en-route to Mercury.

We will present this semi-empiric KTH-model, a modular model to calculate the magnetic field inside the Hermean magnetosphere. Korth et al. (2015 and 2017) published a model, which is the basis for the KTH-Model. In this new version, the calculation of the magnetic field for the neutral current sheet is restructured based on observations rather than ad-hoc assumptions so that the description is more realistic. Furthermore, a new model is added to depict the partial ring current. An analysis of the residuals shows a better visibility of the field-aligned currents. In addition, this model offers the possibility to improve the main field determination.