bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in the global atmospheric energy transport separated by spatial scales in a warming world
Authors: Stoll Patrick , Graversen Rune Grand , Heiskanen Tuomas Ilkka Henrikki , Bintanja Richard
Published: March 2022

The global atmospheric circulation determines the local weather and climate. To better understand this circulation and how it may change in a warming world, we separate the atmospheric energy transport by the spatial scale, the quasi-stationary and transient nature, and the latent and dry-static component in the ERA-5 reanalysis and climate-model simulations with EC-Earth. Different to previous studies that distinguish the scale by wave-numbers, here the meso, synoptic and planetary scales are separated at wavelengths below 2000km, between 2-8000km, and above the latter, respectively. The scale (wavelength) of most transient energy transport is around 5000km for all latitudes and is associated with baroclinic, synoptic-scale cyclones. Transient, synoptic-scale waves are the largest contributor to the energy transport at all latitudes outside the tropics, where the meridional overturning circulation is dominant. Planetary-scale waves are both of quasi-stationary and transient character, strongest at latitudes with much orography, and responsible for most of the inter-annual variability of the energy transport. The energy transport associated with mesoscale waves is negligible.

In a warming world, the moisture transport increases everywhere and in all components, however strongest for planetary waves, making dry areas dryer and moist areas moister, and supporting large and long-lasting events that favour floods and droughts. The total energy transport increases at latitudes smaller than 60 degrees, with the main contribution from quasi-stationary, planetary-scale waves, indicating that weather patterns become more persistent. The changing energy transport can be associated both with changing zonal gradients in temperature and with an atmospheric circulation that becomes more effective in transporting energy.
Advances in understanding the efficacy of root hairs in water uptake
Authors: Ahmed Mutez Ali , Gaochao Cai , Duddek Patrick , Abdalla Mohanned , Carminati Andrea
Published: March 2022

Although the impact of root hairs (RHs) in nutrients uptake is well documented, their role in water uptake and drought tolerance remains controversial. Maize wild type and its hair-defective mutant (rth3) were grown in two contrasting soil textures (sand and loam). We used a novel root pressure chamber to measure the relation between transpiration rate (E) and leaf xylem water potential (ψleaf_x) during soil drying. The hypotheses were: 1) RHs extend the root-soil contact and reduce the decline in ψleaf_x at high E in dry soils; 2) the impact of RHs is more pronounced in sand; and 3) mutants partly compensate for the lack of RHs by producing longer and/or thicker roots. The ψleaf_x(E) relation was linear in wet conditions and became nonlinear as the soils dried. The nonlinearity of the relation occurred more abruptly and at less negative matric potentials in sand (ca. -10 kPa) than in loam (ca. -100 kPa). At slightly more negative soil matric potentials, soil hydraulic conductance became smaller than root hydraulic conductance in both soils. Both genotypes exhibited ca. 1.7 times longer roots in loam, but 1.6 times thicker roots in sand. No differences were observed in the ψleaf_x(E) relation and active root length between the two genotypes. Root hairs had no contribution to soil-plant hydraulics in maize in both sand and loam. These results suggest that the role of root hairs cannot be easily generalized across species and the response of root hydraulics to soil drying is remarkably affected by soil textures.
Fluctuations of the solar wind ion flux near the Earth bow shock
Authors: Sapunova Olga , Borodkova Natalia , Yermolaev Yuri , Zastenker Georgii
Published: March 2022

In our study we analyzing fluctuations of the solar wind ion flux associated with the Earth bow shock using data obtained by the BMSW experiment, installed onboard the SPEKTR-R satellite. The high time resolution of the spectrometer (0.031 s for the plasma flux magnitude and direction and 1.5 s for velocity, temperature, and density) makes it possible to study fine structures in detail.

From 2011 to 2019 SPEKTR-R satellite crossed the Earth bow shock many times. In our work we analyzed more than 200 bow shock crossings including multiple ones. More than half of them had fluctuations near the Earth bow shock front.

It was shown that in 25% of events the frequencies of ion flux fluctuations were in the range of 3-4 Hz. In 5-7% of events the frequencies of ion flux fluctuations lay in the interval of 5-6 Hz. Just few cases had frequencies of ion flux fluctuations equal or more than 7 Hz. In other cases the frequencies of ion flux fluctuations were lower than 3 Hz or no fluctuations were observed at all.

We also observed low-frequencies fluctuations about 0.1 Hz and lower. These fluctuations were also visible by the 1.5 s plasma parameters: protons density and velocity; He++ (alpha particles) density and velocity (including helium abundance).
Terrain visibility can affect landslide data collection
Authors: Bornaetxea Txomin , Marchesini Ivan , Mondini Alessandro , Kumar Sumit , Karmakar Rabisankar
Published: March 2022

Landslide inventories are used for multiple purposes including landscape characterisation and monitoring, or landslide susceptibility, hazard, and risk evaluation. Their quality can depend on the data and the methods with which they were produced. The poor visibility of the territory to investigate offered by the point of observation from which landslides are interpreted is not frequently considered as a source of error in manually produced inventories. In this work, we present an approach to relate visibility and spatial distribution of the information collected in field work based inventories and inventories obtained through interpretation of satellite images.
We first used the r.survey tool and a digital elevation model to model and classify the visibility of the territory explored by field work based inventories. Furthermore, we assumed uniform visibility for inventories obtained through interpretation of satellite images.
Then, we measured the landslide density in the different visibility classes of the field based inventories. Last, we simulated visibility classes for the image based inventories using the road net of the area as virtual observation points, and we measured the relative landslide density.
We applied this approach to four inventories: one was produced by photo-interpretation, another one concerns to a regional multi-temporal database and the other 2 were done by direct field-mapping.
Our results show that 1) the density of the information is strongly related to the visibility in inventories obtained through field work, where landslides are abundant in high visibility classes but rarely reported in low visibility classes; and 2) the density of information is almost constant in inventories obtained by photo-interpretation of images, but they suffer from a marked under representation of small landslides in areas with potentially high visibility, e.g. close to roads. We maintain that the proposed procedure can be useful to evaluate the quality of landslide inventories and drive their correct use.
Spatiotemporal evolution of forest cover and of historical climate data: a case study in the Mediterranean basin 
Authors: Cipolla Sara Simona , Montaldo Nicola
Published: March 2022

A consequence of climate change, less investigated from the hydrological point of view, is the alteration of the frequency and intensity of forest disturbances that can reduce forest productivity, change the distribution of tree species, and shift their range and density. Based on this, this study evaluates the ability of remnants of native forests to resist or adapt to a changing climate. The case study is the island of Sardinia, located within the Mediterranean basin. Sardinia covers a latitudinal gradient of 300 km; and it is one of the least populated and the most forested regions in Italy. It is considered one of the most important biodiversity reservoirs inside the Mediterranean hotspot. From one hand Sardinia is experiencing a decreasing pressure on forests due to human factors, from the other, some studies demonstrate that winter precipitation and runoff are decreasing alarmingly, and this can have an impact on forests. Based on the above, this study aims, through the analysis of 20 years of satellite images (MOD44B), to evaluate forest cover changes and to detect any possible relationship with some of the most important climate variables such as precipitation, air temperature and vapor pressure deficit. Results indicate that in the last 40 years Sardinia has experienced a simultaneous increase in air temperatures (0.026 °C*y-1) and VPD (0.001 kPa*y-1) combined with reductions in both total precipitation (14.03 mm*y-1) and winter precipitation (12.09 mm*y-1), and that the areas with a mean annual precipitation lower than 700 mm went from the 26% in the period 1922-1979, to 63% during 1980-2018, and in effect 1980 was detect as changing point for annual precipitation. These climatic variations have led to an important reduction of the tree cover in some historical forests of Sardinia, and in the broad-leaved ones particularly. The reduction in TC shows a positive correlation with mean annual precipitation (ρ= 0.66) and altitude (0.72), while negative correlations were detected with temperature (ρ= -0.57) and VPD (ρ= -0.48). Results highlight that forests are adapting to climate change, and this may have an impact on local water resources.
Insights into the deep geothermal potential from heat in place calculations of the Berlin/Brandenburg region (Germany)
Authors: Benoit Laureen , Bott Judith , Scheck-Wenderoth Magdalena
Published: March 2022

In geothermal exploration, regional 3D geological models, covering the full extent of a sedimentary basin, can be an efficient basis to assess spatial variations in the deep thermal field and related extractable energy. The term “geothermal potential” has been defined in different ways, considering characteristics of an intended geothermal plant and/or the geological reservoir. In this contribution, we concentrate on the latter geological aspects and combine 3D geological with 3D thermal models of the Berlin/Brandenburg region to assess “heat in place” as a quintessential part of the geothermal potential of differently composed geological units.

Our “heat in place” calculations correspond to a volumetric quantification of contained energy distributed across a series of litho-stratigraphic units showing variable thickness, mean temperature, porosity, density, and specific heat capacity. We set special focus on estimating how the calculated heat varies between different thermal models, derived from either purely conductive heat transport or coupled thermal-hydraulic simulations.

As part of the Northeast German Basin, the Berlin/Brandenburg region is known to be potentially suitable for deep geothermal energy exploitation. As this source of energy is not well-established yet, while energy demand from renewables is increasing in the metropolitan area of Berlin, this study aims at contributing to a more efficient decision making on promising sites for geothermal energy production by means of a series of new geothermal potential maps.
The influence of biofouling on water transport inside porous stones
Authors: Schröer Laurenz , De Kock Tim , Godts Sebastiaan , Boon Nico , Cnudde Veerle
Published: March 2022

During the 21st Century, climate change and improving air quality will alter biological communities and their influence on building stones. While air pollution used to be a principal factor of stone deterioration, it is diminishing in many parts of the world. These environmental changes affect the aesthetics of building stones, and fewer black gypsum crusts will form, while more biological-induced discolorations could occur. Within the British Isles, it resulted in the “greening” of monuments after increased algal growth. Besides aesthetical damage, the formation of biofilms could affect water transport and retention. Changes in the water-stone relationship should be studied in detail because moisture is the most significant facilitator of stone alteration, leading to physical, chemical and further biological weathering.

This topic was intensely studied on soils. However, knowledge of the effect of biofilms on water transport and retention of stones is limited. For this reason, three porous natural building stones: Ernzen, Euville and Savonnières, were biofouled at the outer surface with the cyanobacteria Phormidium autumnale. The colonization was estimated by spectrophotometry, and their relationship with the stones was studied by Scanning Electron Microscopy (SEM), Environmental SEM (ESEM) and optical microscopy on thin sections. Based on the European standards, the water transport properties were determined of biofouled and untreated samples.

Microscopy showed that the biofilms covered the surface while they spanned over and closed numerous pores. They had a measurable effect on water transport and retention and reduced the rate of capillary water absorption and drying in combination with higher moisture content after (vapor) sorption. Moreover, the biofilms changed the surface wettability and induced near hydrophobic conditions in a dry state while no effect was measured on the water vapor diffusion and air permeability. These changes can alter the material properties and other processes like salt weathering and freeze-thaw damage. As swelling and shrinkage were observed by ESEM, the properties and physical effects of biofilms are expected to change with fluctuating relative humidity.
Midlatitude cyclone features associated with extreme winds and gusts in the seas surrounding the UK
Authors: Gentile Emanuele , Gray Suzanne L.
Published: March 2022

Located near the end of the North Atlantic storm track, the UK’s surrounding seas are characterised by a highly variable wind climate, making prediction of wind speeds challenging at all time scales. While wind speed trends over the UK’s land and seas have been the focus of several studies of the literature in the past 20 years, the question of what is the current systematic link between observed extreme wind speeds (and gusts) over these seas and distinct sub-synoptic features of midlatitude cyclones is, to date, unanswered.  To address this question, we have performed a 10-year climatological analysis of the observed extreme wind speeds and gusts, presenting the distribution of extremes and the prevailing wind direction, along with an analysis of their inter- and intra-annual variability. We find that between the 70 and 85% of the observed top 1% extreme wind and gust events recorded at each network site are within 1000 km of the centre of a cyclone (tracked in the ERA5 reanalysis), and that an even higher proportion of the top 0.1% of the wind and gust events is associated with a cyclone centre (between 80 and 100% depending on the site).  We then determine at each site whether the warm or cold conveyor belt flows are more likely to lead to extreme wind or gust events. Combining the observed extreme winds and gusts data with reanalysis significant wave heights, we further discuss the relationship between extreme winds and extreme ocean wave heights, and consider the relevance of the results to the safety and the smooth running of the operations of the wind energy and oil and gas industries in the UK’s surrounding seas. 
Ocean Mesoscale Variability: A Case Study on the Mediterranean Sea From a Re-Analysis Perspective
Authors: Bonaduce Antonio , Cipollone Andrea , Johannessen Johnny A. , Staneva Joanna , Raj Roshin P. , Aydogdu Ali
Published: March 2022

The mesoscale variability in the Mediterranean Sea is investigated through eddy detection techniques. The analysis is performed over 24 years (1993–2016) considering the three-dimensional (3D) fields from an ocean re-analysis of the Mediterranean Sea (MED-REA). The objective is to achieve a fit-for-purpose assessment of the 3D mesoscale eddy field. In particular, we focus on the contribution of eddy-driven anomalies to ocean dynamics and thermodynamics. The accuracy of the method used to disclose the 3D eddy contributions is assessed against pointwise in-situ measurements and observation-based data sets. Eddy lifetimes ≥ 2 weeks are representative of the 3D mesoscale field in the basin, showing a high probability (> 60%) of occurrence in the areas of the main quasi-stationary mesoscale features. The results show a dependence of the eddy size and thickness on polarity and lifetime: anticyclonic eddies (ACE) are significantly deeper than cyclonic eddies (CE), and their size tends to increase in long-lived structures which also show a seasonal variability. Mesoscale eddies result to be a significant contribution to the ocean dynamics in the Mediterranean Sea, as they account for a large portion of the sea-surface height variability at temporal scales longer than 1 month and for the kinetic energy (50–60%) both at the surface and at depth. Looking at the contributions to ocean thermodynamics, the results exhibit the existence of typical warm (cold) cores associated with ACEs (CEs) with exceptions in the Levantine basin (e.g., Shikmona gyre) where a structure close to a mode-water ACE eddy persists with a positive salinity anomaly. In this area, eddy-induced temperature anomalies can be affected by a strong summer stratification in the surface water, displaying an opposite sign of the anomaly whether looking at the surface or at depth. The results show also that temperature anomalies driven by long-lived eddies (≥ 4 weeks) can affect up to 15–25% of the monthly variability of the upper ocean heat content in the Mediterranean basin.
Efficient probabilistic parameter calibration of landslide run-out models via Bayesian active learning
Authors: Zhao Hu , Kowalski Julia
Published: March 2022

Landslides, such as debris flows and avalanches, are common natural hazards worldwide. They pose an ongoing threat to life and property. Landslide run-out models that have been developed over the past decades are powerful tools to assess landslide risks and design mitigation strategies. Due to the simplification of real-world landslide processes, the models often contain parameters that rely on calibration of past landslide events where field data are available. Deterministic calibration methods like traditional trial-and-error calibration suffer from the non-uniqueness issue and cannot account for uncertainties associated with field data. Probabilistic calibration methods like Bayesian inference avoid the two issues. However, their usage is hindered by high computational costs due to the long run time of a single run-out model evaluation and the large number of required model evaluations. 

To address the research gap, this work proposes an efficient probabilistic calibration method for parameter estimation of landslide run-out models. The new method couples landslide run-out modeling, Bayesian inference, Gaussian process emulation, and active learning. We implement it in a Python-based environment. Its feasibility and efficiency are tested based on an extensive synthetic case study. Owing to Gaussian process emulation and active learning, our new method overcomes the computational bottleneck by reducing the number of required model evaluations from thousands to a few hundreds. It is therefore expected to advance the state-of-the-art in parameter estimation of landslide run-out models. In addition, the impact of different types of field data on calibration results is studied using the proposed method. 
THERMAL: Sampling Atmospheric Convection Using Paragliders
Authors: Palenik Juraj , Spengler Thomas
Published: March 2022

Atmospheric convection is responsible for turbulent transport of heat, moisture, and momentum and fuels the convective cloud formation. Due to lack of observations, numerical prediction models treat convection using sometimes inadequately constrained parametrization schemes. Observations of atmospheric convection to further constrain these parameterisations are notoriously difficult to obtain due to the intermittent, localized,  and turbulent character of convection. However, every day, hundreds of paragliding, hang gliding, and gliding pilots probe the convective boundary layer in hope of finding the best convective thermals. They spend years learning the art of finding and flying in the convective air, while they proudly share their flight tracks online. In this presentation we show how tracks of these engineless aircrafts can be used to sample atmospheric convection. We showcase a dataset from a paragliding championship to classify convection. We elaborate on how the international databases can be used to characterize atmospheric convection and aid building parametrizations based on machine learning.
Southern Ocean cloud reductions in CMIP6 forcing experiments as a contributor to intermodel spread in Antarctic warming
Authors: Jönsson Aiden , Bender Frida
Published: March 2022

It is now well known that CMIP6 models have a higher average and range of climate sensitivities than previous generations of models, which has been shown to be in part caused by weaker negative short wave radiative cloud feedbacks in response to greenhouse gas (GHG) forcing. These weaker negative cloud feedbacks are understood to be caused by a number of factors, including warm rain precipitation bias and Southern Ocean (SO) deep convection slowdown.

We find that coupled models in strong forcing (abrupt quadrupling of CO2) experiments with greater reductions in Southern Hemisphere (SH) extratropical and SO cloud cover and thus albedo also exhibit greater polar amplification in the SH, namely: increased poleward heat transport, greater surface warming at high latitudes, and a decrease in Antarctic surface albedo. Precipitation increases in the Antarctic polar region with warming, but not evenly; liquid-phase precipitation increases in the Antarctic sea ice zone while ice-phase precipitation increases on the continent. These responses occur roughly three decades after the onset of forcing, and continued surface warming in models with greater SH extratropical cloud loss beyond this point occurs mainly in the SH extratropics, especially at high latitudes, rather than globally.

Here, we aim to explore the connection between Antarctic warming and cloudiness in the SH extratropics and SO. Detailing the process of Antarctic warming in these models can help to explain some of the intermodel spread in Antarctic polar responses to GHG forcing, as well as to further constrain predictions of future climate changes in response to anthropogenic forcing, as these models also include some of the highest climate sensitivities of the CMIP6 ensemble.
Assessing ecosystem responses to different drivers of climate change 
Authors: Moustakis Yiannis , Fatichi Simone , Onof Christian , Paschalis Athanasios
Published: March 2022

Altered precipitation, elevated CO2, increased temperature and atmospheric drought under climate change are expected to jointly affect ecosystem responses in complex and yet uncertain ways, depending on climate and vegetation type. In this work, we study ecosystem responses at 33 sites in North America, belonging to FLUXNET, covering a wide range of climates and biomes, by making use of the continental-wide WRF convection-permitting model simulations of the current and future (RCP8.5) climate (~4km, 1hr). WRF simulations for the first time provide us with the necessary information to fully understand ecosystem dynamics from the hourly to the decadal scales. 

Specifically, we employ a stochastic weather generator, informed by the WRF simulations, and the state-of-the-art Tethys & Chloris (T&C) terrestrial ecosystem model to perform multi-year multi-factorial numerical experiments and study the separate and joint effects of;  

a) altered precipitation,  

b) elevated CO2, increased temperature and  

c) atmospheric drought on ecosystems.   

We study changes in the interannual variability of carbon and water fluxes at the ecosystem scale and their drivers, benefitting from our stochastically extended “100-year-long" numerical experiments, which allow taking into account climate’s stochasticity. We also focus on between- and within-treatment variability and identify the signal-to-noise ratio, which can have serious implications regarding whether field manipulation experiments, which typically last a few years, can capture the emerging signal. We further investigate the importance of short-term meteorological variability for carbon fluxes at coarser temporal scales, and we quantify changes in ecohydrological aridity. Finally, we assess changes in the phenological cycle and their impact on the annual cycle of carbon and water fluxes. 
Can remote green hydrogen production play a key role in decarbonizing Europe? A cradle to gate LCA of hydrogen production in Austria, Belgium and Iceland. 
Authors: Vilbergsson Kristjan , Dillman Kevin , Emami Nargessadat , Ásbjörnsson Einar , Heinonen Jukka , Finger David
Published: March 2022

There has been a global spike in interest in using hydrogen as an energy carrier to decarbonize hard-to-abate sectors. From a European perspective, with the interest in greater use of hydrogen for this purpose, EU member states are considering varied means to either produce hydrogen nationally or to import remotely-produced H2. However, the mitigation potential of hydrogen is heavily dependent on how the hydrogen is produced (i.e. steam methane reforming or electrolysis) and under what conditions (i.e. using CCS technologies or for electrolysis the source of the electricity used). Thus, a variety of studies have considered the life cycle impacts of different hydrogen production conditions, taking into account different sources of electricity during electrolysis, operating hours (i.e. for when using intermittent renewable energy technologies), and transportation of the hydrogen. However, these different conditions are often studied in isolation, making cross-comparisons needed to assess the environmental trade-offs of locally produced versus imported hydrogen difficult. Therefore, to allow for such an assessment in this study, we consider the life cycle impacts of H2 production temporally and spatially, at three different locations in Iceland, Austria, and Belgium using locally available renewable energy sources, as well as the local grids in each location. Our cradle to gate life cycle assessment includes the transport from the production site to the final utilization site at potential gates in Europe. Our results indicate that the carbon footprint of H2 production depends primarily on the energy mix, while transportation of H2 generates a minor impact.
Energetic ions within Ganymede’s magnetospheric environment
Authors: Plainaki Christina , Massetti Stefano , Jia Xianzhe , Mura Alessandro , Milillo Anna , Grassi Davide , Filacchione Gianrico
Published: March 2022

The dynamics of the energetic ion circulation within Ganymede’s magnetosphere and the related surface precipitation patterns determine the variability of surface sputtering and radiolysis and the generation of the moon’s exosphere. The planetary space weather conditions around this icy moon have a long-term influence also on its surface evolution history.

In this work, some key aspects of the energetic ion circulation within the magnetosphere of Ganymede will be discussed. The results of a single-particle Monte Carlo model driven by the electromagnetic fields from a global MHD model will be presented and compared, where possible, with other findings in literature, from a planetary space weather perspective. The estimated surface precipitation patterns for different ion species/energies and configurations between the Jupiter plasma sheet and Ganymede will be also discussed. Special focus will be given on the implications that the ion precipitation on Ganymede’s surface may have in the water sputtering rate. The results of the current study are relevant to ESA’ s JUICE mission.
Large Amplitude Oscillations in Solar Filaments Caused by Solar Jets
Authors: Joshi Reetika , Luna Manuel , Schmieder Brigitte , Moreno-Insertis Fernando , Chandra Ramesh
Published: March 2022

Large amplitude oscillations (LAO) are often detected in filaments. Their origin has been associated with shock waves or to interaction with eruptions and jets. In this study we present  two examples of LAOs due to solar jets interaction with filaments on February 3-5 2015 and March 14 2015.  The filament eruption on March 14 was followed by a two step filament eruption along with a CME and become the strong geomagnetic storm of Solar Cycle 24 on 17 March 2015. These LAOs are  analysed by using time-distance diagnostics. The detected LAOs have periods of around 60 minutes and are damped after three oscillations. The observations are consistent with the results of a recent developed theoretical model of jet and filament interaction. The jets are associated with very weak flares which did not initiate any EUV wave. The role of waves as trigger of these oscillations can be discarded for these two events. 

 
Nitrogen fixation by lightning and its role for early life on Earth and exoplanets
Authors: Barth Patrick , Stüeken Eva E. , Helling Christiane , Rossmanith Lukas , Walters Wendell , Claire Mark
Published: March 2022

Nitrogen is an essential building block of DNA, RNA, and proteins and, subsequently, it must have been bioavailable since the origin of life. On modern Earth, biological sources are mostly responsible for making nitrogen bioavailable via N2 fixation with only a few percent coming from abiotic sources. On early Earth, before the origin of life and the onset of biological nitrogen fixation, these abiotic sources such as lightning must have been the dominant producer of bioavailable nitrogen. Previous experiments have shown that in N2-dominated atmospheres lightning leads to the formation of nitrate (NO3-) and nitrite (NO2-), which could not only have facilitated the origin of life but also sustained the earliest ecosystems. This hypothesis has been difficult to test with the available rock record because geochemical fingerprints of this fixed nitrogen source have not been developed. We present new results from spark discharge experiments in varying atmospheric compositions corresponding to different points of time in Earth’s evolution. We find substantial amounts of nitrate are produced in an N2/CO2 atmosphere. Furthermore, we investigate the effect of lightning on the isotopic composition of the resulting nitrogen oxides in solution. Our fixed nitrogen is depleted in heavy 15N in comparison to atmospheric N2, in line with rock samples older than 3.2 billion years. For the first time we can assess to what degree lightning chemistry may have influenced the origin and early evolution of life. However, the spark in our experiment is much smaller and cooler than lightning channels in Earth’s atmosphere. To extrapolate our experimental results to full-scale planetary atmospheres we plan to complement them with simulations of the atmospheric chemistry of exoplanets and Earth. This will allow us to extend our experiments to real lightning conditions and develop observable tracers for lightning chemistry in exoplanetary atmospheres. Being able to predict the bioavailability of nitrogen on other worlds will be another factor determining the potential habitability of these worlds.
Impact of orography on current and future extreme sub-daily precipitation
Authors: Lusito Letizia , Marra Francesco , Dallan Eleonora , Zaramella Mattia , Troccoli Alberto , Borga Marco
Published: March 2022

Major natural hazards in mountainous regions, such as flash floods and debris flows are mainly triggered by short-duration extreme precipitation. A better understanding of how these events are affected by orography can significantly improve risk management and adaptation to changing climate. Recently, significant progress has been made in high-resolution (particularly convection-permitting) modelling of precipitation over complex terrain, with the advantages of improved topographical features, physical representation of mountain-precipitation interactions, and avoided errors from convective parameterizations.

Here, we examine the mountain-precipitation interactions for subdaily precipitation extremes from three 10-year time slices (historical 1996-2005, near-future 2041-2050, and far future 2090-2099 – under the RCP8.5 scenario) of COSMO-crCLIM model simulations at 2.2 km resolution. We use the Upper Adige river basin in the Eastern Italian Alps, with a good coverage of high-quality precipitation data, as a case study. The ability of the convection-permitting model to represent the orographic impact on precipitation is examined based on a comparison between 2000-2009 simulations from the COSMO model run driven with ERA Interim, and observations from the local rain gauge network.

Given the availability of relatively short time-slices of model simulation, which prevent the use of conventional extreme value methods, we use here methods based on the concept of ordinary events, which are all the independent events that share the statistical properties of extremes. This offers now an opportunity for deriving frequency analyses from shorter data records, promising improved applications based on convection precipitation simulations.
Plant phosphorus-use and -acquisition strategies and energy costs in Amazonia
Authors: Reichert Tatiana , Rammig Anja , Fuchslueger Lucia , F. Lugli Laynara , A. Quesada Carlos , Papastefanou Phillip , Gregor Konstantin , Fleischer Katrin
Published: March 2022

Phosphorus (P) is one of the main limiting nutrients for forest productivity in Amazonia. To meet P needs, plants invest resources in different strategies which may increase their P-use efficiency, e.g., by resorbing P from senescing organs, or increase their P-acquisition efficiency, e.g., by acclimating fine root traits (architectural, morphological, physiological, and symbiotic). P-acquisition strategies can be categorized into foraging strategies related to the uptake of plant-available P or mining strategies related to the mobilization and uptake of less available forms of P. However, little is known about the effects of soil P on plant P-use and -acquisition strategies in Amazonia. Therefore, we have conducted a literature review and synthesized the current knowledge on the variation of different P-use and -acquisition strategies across soil P fertility gradients and their response to P fertilization in Amazonia and other tropical forests (Reichert et al., in press). We provide a conceptual framework on the distribution of these strategies in Amazonia and propose that, at the plant community level, foraging strategies (via fine roots and arbuscular mycorrhizas) are more prevalent and may contribute most for plant P uptake in soils with intermediate to high P availability, and leaf P resorption and mining strategies (via root exudation of acid phosphatases and organic acids) in soils with intermediate to low P availability (Reichert et al., in press). Here, we suggest that the investment in different P-acquisition strategies may be partially explained by the energy cost per unit P acquired. Based on the assumption that this cost varies with strategy and the form of P and its concentration in the soil (Raven et al., 2018), we have developed a stand-alone theoretical model to predict plant investments in P acquisition and test our conceptual framework. We constrain the model with field observations on forest growth and soil nutrients from sites in Amazonia and explore possible shifts in P-acquisition strategies along soil P fertility gradients.

Raven JA, Lambers H, Smith SE, Westoby M. 2018. Costs of acquiring phosphorus by vascular land plants: patterns and implications for plant coexistence. New Phytologist 217(4): 1420-1427.

Reichert T, Rammig A, Fuchslueger L, Lugli LF, Quesada CA, Fleischer K. In press. Plant phosphorus-use and -acquisition strategies in Amazonia. New Phytologist.
Kinematic and tectonic analysis of the Baza and Galera Fault (S Spain). Insights from GNSS data
Authors: García-Tortosa Frank , Alfaro Pedro , Sánchez-Alzola Alberto , Martin-Rojas Ivan , Galindo-Zaldívar Jesus , Avilés Manuel , López Garrido Angel Carlos , Sanz de Galdeano Carlos , Ruano Patricia , Martínez-Moreno Francisco Jose , Pedrera Antonio , de Lacy Maria Clara , Borque Maria Jesus , Medina-Cascales Ivan , Gil Antonio Jose
Published: March 2022

We here discuss the results of a local GNSS episodic network from the Baza sub-Basin (S Spain). This network including six sites, was established in 2008 and has been measured seven times since then. Our data permit us to present the first short-term slip rates for the two active faults in this area. The main active structure is the normal Baza Fault. We estimate slip rates for this fault ranging between 0.3±0.3 mm/yr and 1.3±0.4 mm/yr. For the strike-slip Galera Fault, we quantify the slip rate as 0.5±0.3 mm/yr. These values are higher than previously reported long-term slip rates. We postulate that the discrepancy for the Baza Fault between short-term and long-term slip rates could indicate that the fault is presently in a period with a displacement rate higher than the mean of the magnitude 6 seismic cycle. Moreover, the velocity vectors that we obtained also show the regional tectonic significance of the Baza Fault, as this structure accommodates one-third of the regional extension of the Central Betic Cordillera.

Our results also show that the Baza and Galera Faults are kinematically coherent and they divide the Baza sub-Basin into two tectonic blocks. This points to a likely physical link between the Baza and Galera Faults; hence, a potential complex rupture involving both faults should be considered in future seismic hazard assessment studies.
A Modified Mask-RCNN Algorithm for Intelligent Identification of Landslide Based on High-resolution Remote Sensing data
Authors: Wang Jingjing , Chen Gang , Derron Marc-Henri , Jaboyedoff Michel
Published: March 2022

Deep learning is a data-driven approach that requires high-quality labeled data to construct training and evaluation datasets. However, there are few open landslide data sets at present, and the degree of standardization of data sets is low. Now, the most advanced instance segmentation algorithms require strongly supervised learning. The cost of acquiring new categories of images is prohibitive. A question is raised: Is it possible to train high-quality instance segmentation models for early landslide disaster identification on the premise that not all categories are marked with complete instance segmentation annotations?

This article mainly deals with the intelligent identification of the small and medium-scale loess-bedrock historical landslides in the east Gansu Province. We proposed a modified instance segmentation algorithm based on transfer learning. Specifically, (1) A self-made landslide dataset was constructed. Google Earth images were used as the data source, and Arc GIS was selected as the landslide interpretation software. Based on DEM and 1:50,000 detailed regional geological hazard survey data, landslide boundaries were manually circled using the dataset annotation software（label me）according to the landslides' features of color, spectrum, vein, and surface roughness in optical images. The method of regional separation of datasets was used, with Anding district of Dingxi city as the validation set (15%), and Tianshui city, Longnan city, and Qingyang city as the sampling areas of the training set (70%) and testing set (15%) in the dataset. (2) A novel segmentation algorithm for landslide instances was proposed. The algorithm combined partially supervised training with weight transfer function to achieve high precision landslide classification and boundary recognition on data set constructed by mixed label annotation method. (3) A new method of Mask scoring was adopted to solve the problem that the accuracy of instance segmentation was affected by the lack of Mask scoring in Mask-RCNN.

The results show that the proposed method is superior to other algorithms in precision, accuracy, and recall rate. In addition, the Mask-IOU threshold value of 0.5 was used to estimate the average accuracy higher than the Mask-IOU threshold value of 0.75. The improved algorithm is in the segmentation of small and medium-sized landslides better than for large landslides, which will help solve the problem that it is difficult to comprehensively monitor the small and medium-sized landslides in the geological field survey. And our algorithm is not sensitive to the diffident backbone network and can achieve stable improvement on different Backbones. The average accuracy is about 3.1. The result of the experiment verified with the landslide field survey data in the validation area demonstrates this algorithm is stable and adaptable.
Projection of flood seasonality Changes in the Himalayan Region River due to global warming, taking the Garhwal Himalayas river basin as an example
Authors: Singhal Prachi , Goel Narendra Kumar , Agarwal Ankit , Bronstert Axel , Vormoor Klaus
Published: March 2022

The impact of a warming climate on snow- and rain-dominated river basins such as the Garhwal Himalayas basin constitutes both a major research challenge and the potential of a severe socio-economic risk. The particular combination at the Garhwal, of hydrometeorological and hydrographic conditions entails merging and superposing two presently distinct seasonal phenomena: snowmelt induced spring floods and rainfall generated summer floods. This study focuses on the projection of seasonality changes in floods in a Garhwal Himalayas basin under global warming. The research in this context is rather uncertain in the proposed study area of the Himalayas, mainly due to the scarcity and unavailability of long-term and high-resolution meteorological data in that region. But after setting up Automatic Weather Stations and Gauge and Discharge sites in the Garhwal region in 2016, the observed data of the past five years lay the basis for understanding the different flood generating regimes. We have analysed the IMD historical maximum monthly rainfall (1901-2020) and maximum temperature (1951-2020) over the study region and found evidence of shifting of maximum rainfall peak backward up to the month of June and maximum temperature peak shifting forward to June (earlier triggering snowmelt induced peak then); if warmer climate scenarios are experienced in future. We also compared the different precipitation datasets available with respect to the observed data at daily, monthly, quarterly and yearly time scales. Those data are crucial for any analysis of possible changes in seasonal hydro-meteorological conditions. We found that the IMD precipitation dataset matches best the observations and the projected climate ensemble of chosen dataset (NEX-GDDP) required significant correction with respect to observed data to counter underestimation. Therefore, we have used quantile-based mapping to adjust the biased projected climate dataset of NEX-GDDP. Also, the corrected projected precipitation of time window 2071-2099 of RCP 4.5 and 8.5 scenarios is found to be magnitude wise higher than that of the corrected historical time window 1971-2000. This clearly indicates the possible occurrences of changes in floods, though we are well aware about the high uncertainties of projected future precipitation conditions. Thus, our analysis poses the potential of bridging the gaps of understanding different flood generating regimes and their future possibilities for better preparedness against natural hazards in the Himalayan region.
Labile DOC increases P removal efficiencies in the benthic zone and shifts P thresholds towards higher P concentrations
Authors: Perujo Nuria , Neuert Lola , Fink Patrick , Kamjunke Norbert , Sunjidmaa Nergui , Weitere Markus , Graeber Daniel
Published: March 2022

Biofilms in river sediments play a key role in P retention in aquatic ecosystems. Most studies in freshwater ecosystems focus mainly on the autotrophic component of biofilms but little is known about the role of heterotrophic components on P removal. It is known that DOC in some streams is of low bioavailability, hence, resulting in severe DOC and P co-limitation of heterotrophic biofilm growth which could then constrain P removal efficiency. How DOC limitation affects P removal efficiency in the benthic zone and how it modifies P thresholds (i.e. concentration from which the removal efficiency decreases) are still open questions.

We performed an experiment in the MOBICOS (Streamside Mobile Mesocosms) in the Holtemme River (Germany) to study the role of labile DOC on P thresholds in P retention in the bed-sediment biofilm community. Our flume experiment followed a BACI design (before: no DOC addition; after: labile DOC addition at C:P molar ratios >100; control: basal P and DOC concentrations; impact: P concentrations ranging from 25 µg P/L to 420 µg P/L).

Our results show that labile DOC increases the P removal efficiency of the system (i.e. P water mass balances in the flumes) and shifts P thresholds for P removal towards higher P concentrations meaning that at a given P concentration higher P removal efficiency is achieved if the system is supplied with labile DOC. Labile DOC activated the heterotrophic component in the flumes and benthic biofilms receiving labile DOC show higher bacterial density and higher P accumulation compared to the ones not receiving labile DOC.

Our results demonstrate that the heterotrophic biofilm community plays a key role in in-stream phosphorus retention. As it relies on availability of labile DOC, the interaction of DOC and P dynamics need consideration in models for stream nutrient processing and retention.