bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in the actual catchment evapotranspiration in the Western Carpathians in Slovakia
Authors: Szolgay Jan , Keszeliova Anita , Hlavcova Kamila , Gribovszki Zoltan , Kalicz Peter , Kandera Miroslav
Published: March 2022

Actual catchment evapotranspiration, which includes all forms of evaporation and transpiration through plants, plays an important role in the water, energy, and carbon cycles. This contribution aims to explore trends in the actual catchment evapotranspiration based on the analysis of the components of the long-term hydrological balance of selected river basins in the Western Carpathians and detect changes attributable to changing landuse and climate conditions. We have used high-quality gridded data sets of precipitation and air temperatures from the CarpathClim project for the water balance. Temporal changes in the catchments’ average air temperature, precipitation, runoff, and their differences (considered as an index of the actual evapotranspiration) have been estimated for 49 years of data and compared between two non-overlapping sub-periods (25 and 24 years). Given that both inputs into the equation of the long-term hydrological balance contain uncertainties, we also used proxy evapotranspiration data modelled according to the Budyko-Tomlain method for comparison. Changes in land use were evaluated from the CORINE project. This allowed us to consider the impact of the rising air temperature and, in part, the local physiographic factors, on the changes in runoff and actual catchment evapotranspiration as the main drivers of changes in the hydrological balance. In particular, the increase in air temperature was found to be statistically significant across the transect. The main conclusion related to water resources management is that the hydrological balance has changed towards an increase in actual catchment evapotranspiration and a decrease in runoff. An increase in the catchment precipitation was present in the trends but was not statistically significant. The Budyko-Tomlain actual evapotranspiration proxy series confirmed the tendencies in the actual catchment evapotranspiration with significant trends. However, local factors of runoff generation, especially catchment storage, can exhibit an influence at higher elevations (approx. above 800 m a.s.l.), thereby partially disguising the expected general tendencies at a given altitude. These factors can both lessen or intensify the changes in runoff and actual catchment evapotranspiration in catchments at similar altitudes. On the other hand, in lower elevations where runoff generation is less intensive, the influence of the climatic factors is decisive. The research was supported by the Slovak Research and Development Agency under Contract Nos. APVV-18-0347 and APVV-20-0374, and the VEGA Agency Grant No. 1/0632/19. The support is gratefully acknowledged.
Multidimensional Analysis of Serpentinite Dehydration Networks and Implications for Volatile Flux in Subduction Zones 
Authors: Arias Austin , Beinlich Andreas , Eberhard Lisa , Scambelluri Marco , Plümper Oliver
Published: March 2022

Subduction zones are principal pathways for the cycling of volatiles such as  hydrogen and carbonfrom the Earth’s surface to the mantle and back to the atmosphere. This cycling has significant long-term effects on Earth’s climate. However, the processes that lead to volatile release during subduction and total volatile fluxes are poorly understood. In our study, we will quantify and characterize the network architecture of dehydration pathways exhibited as mineralized olivine-bearing metamorphic veins in the exhumed meta-serpentinites from the Erro-Tobbio unit, Italy [1]. Applying network analytical methods and graph theory both macroscopically and microscopically can provide the mode of propagation and describe the controlling factors affecting the evolution of these dehydration networks. Furthermore, multiscale observations can confirm the scalability of the vein network and if quantitative results such as permeability or volatile flux can be extrapolated to larger scales.

Along with 2-D network analysis, these vein networks will be analyzed in 3-dimensions using X-ray tomography and sophisticated machine-learning methods, such as generative adversarial networks. The results of both will be compared, which can then assure whether current machine-learning methods can effectively create statistically equivalent copies of these networks. Lastly, the synthesis of 2-D and 3-D multiscale results should provide meaningful parameters for accurate calculations of volatile flux during the dehydration of subducting slabs. 

 

[1] Plümper et al. (2017) Nature Geoscience 10(2), 150-156.
Imaging the Geospace Via Data-Based Empirical Reconstruction of Magnetospheric Events
Authors: Andreeva Varvara , Tsyganenko Nikolai
Published: March 2022

Quantitative empirical models combined with historical data archives serve as one of the main tools to reconstruct the geospace magnetic field dynamics during space weather events. The essence of the approach is to develop a flexible mathematical framework, aimed to derive the magnetosphere's response to varying interplanetary conditions using multi-year pools of spacecraft observations. There exist two different ways to formulate an empirical model: (i) the so-called "modular" approach, in which the total field is associated with a few current systems having a priori defined geometry, implied by previous experimental and theoretical knowledge. Alternatively, (ii) the magnetic field can be expanded into series of formal basis functions with a minimum of predetermined assumptions. Both techniques have their own pluses and minuses. In the present paper, an efficient method is described to maximize the advantages and minimize the drawbacks by combining the modular part of the model field, on the one hand, and the basis function expansions, on the other, into a synthetic "hybrid" approximation. In such a setting, the modular part renders the main features of the magnetospheric structure, while the basis function expansions take on the role of a second-order correction that removes the remaining inaccuracies. Our primary goal here is to reconstruct the magnetosphere dynamics during individual events rather than develop a universal magnetic field description. For that purpose, the hybrid model is combined with the "nearest-neighbor" data mining in the space of magnetospheric state variables, which allows one to create sequential data subsets and reconstruct the magnetic field for different time moments during a specific storm or substorm. The importance of proper choice of the state variables is discussed, including the ground activity indices and the solar wind/IMF parameters.
The ATTO Micrometeorological Intercomparison Experiment (ATMIX)
Authors: Mortarini Luca , Dias Nelson , Quaresma Dias Cleo , Brondani Daiane , Acevedo Otavio , Manzi Antônio , de Oliveira Pablo , Tsokankunku Anywhere , Rossato Fernando , Araújo Alessandro , Soergel Mathias , Nobre Quesada Carlos Alberto
Published: March 2022

A central constituent of the ATTO project  is the deployment of an array of sonic anemometers to measure vertical profiles of means and second-order moments of the wind velocity vector. The two instruments used are the Campbell Scientific Instruments CSAT-3B and the Thies Ultrasonic Anemometer 3D. The accuracy of the vertical profiles of turbulent quantities critically depensds on an absence of bias between the measurement levels; however, dedicated intercomparisons of the sonic anemometers used in ATTO have not been previously performed.  The main objective of the experiment was to check how close the sonic anemometers designated to be installed respond to the same atmospheric conditions, and to develop confidence in interpreting the measured data. 
Influencing factors on the adsorption-desorption processes of Pharmaceutically Active Compounds (PhACs) in various agricultural soils
Authors: Szabó Lili , Vancsik Anna , Bauer László , Jakab Gergely , Kondor Attila , Filep Tibor , Szalai Zoltán
Published: March 2022

The fate of Pharmaceutically Active Compounds (PhACs) in the environment may depend on a number of interrelated processes. Their environmental risk is mainly influenced by their adsorption and desorption processes in the soil. The present work aimed to study the adsorption and desorption of PhACs (17α-ethinyl estradiol (EE2), carbamazepine (CBZ), diclofenac sodium (DFC)) on various agricultural soils formed under different redox conditions: an Arenosol with fully aerobic conditions and a Histic Gleysol sample with suboxic and anoxic conditions. The objectives of the study were to investigate how the soil properties modify the sorption processes of the PhACs. Adsorption isotherms were applied to estimate the model parameters using Langmuir, Freundlich and Dubinin-Radushkevich model in a batch technique experiment. The different composition of the soil samples significantly affected the amount of adsorbed PhACs (CBZ, DFC, EE2). Top soil samples with a high organic matter content adsorbed higher amounts of PhACs, while the amount of adsorbed PhACs decreased gradually with depth. In desorption experiments, the amount of PhACs released also varied with depth. In contrast, the rate of desorption was lowest at the topsoil samples and increased with depth. In samples where the deeper levels were characterised by higher clay mineral content (e.g. the C-level of the Histic Gleysol), significantly less PhACs could be desorbed. The physico-chemical properties of the soil showed that the amount of the desorbed PhACs mainly influenced by the specific surface area and clay content of the soil. This study could be useful for understanding of the movement of PhACs in soils formed under different conditions. This study was funded by the Hungarian National Research, Development and Innovation Fund (2020-1.1.2-PIACI-KFI-2021-00309).
Impacts of winter storms on residential building damage - Modeling claim ratio considering parameters of vulnerability and exposure 
Authors: Trojand Andreas , Becker Nico , Rust Henning
Published: March 2022

Severe winter storms are one of the most damaging natural hazards for European residential buildings. Previous studies mainly focused on the loss ratio (loss value/total insured sum) as a monetary value for damages (e.g. Prahl et al. 2012; Pardowitz et al. 2016). In this study the focus is on the claim ratio (number of insured claims/number of contracts), which is derived from a storm loss dataset provided by the German Insurance Association. In a first step, loss ratios and claim ratios in German administrative districts are compared to investigate differences and similarities between the two variables. While there is no significant change in the ratio between claim ratio and loss ratio with increasing wind speeds, a tendency for lower loss ratios in urban areas can be confirmed. In a second step, a generalized linear model for daily claim ratios is developed using daily maximum wind gust (ERA5) and different non-meteorological indicators for vulnerability and exposure as predictor variables. The non-meteorological predictors are derived from the Census 2011. They include information about the district-average construction years, the number of apartments per buildings and others to get a better understanding of these factors concerning the number of buildings affected by windstorms. The modeling procedure is divided into two steps. First, a logistic regression model is used to model the probabilty of storm damage occurence. Second, generalized linear models with different link functions are compared regarding their ability to predict claim ratios in case a storm damage occured. In a cross-validation setting a criteria for model selection is implemented and the models of both steps are verified. Both steps show an improvement over the climatological forecast.
Koopman eigenfunctions estimation from reproducing kernel Hilbert space manifold, and ensemble data assimilation
Authors: Tissot Gilles , Mémin Etienne , Hug Bérenger
Published: March 2022

This study aims at proposing a new framework to perform ensemble-based estimations of dynamical trajectories of a geophysical fluid flow system. To perform efficient estimations, the ensemble members are embedded in a set of evolving reproducing kernel Hilbert spaces (RKHS) defining a manifold of spaces, we nicknamed Wonderland, due to its analytical properties.

The method proposed here is designed to deal with very large scale systems such as oceanic or meteorological flows, where it is out of the question to explore the whole attractor, neither to run very long time simulations. Instead, we propose to learn the system locally, in phase space, from an ensemble of trajectories.

The novelty of the present work relies on the fact that the feature maps between the native space and the RKHS manifold are transported by the dynamical system. This creates, at any time, an isometry between the tangent RKHS at time t and the initial conditions. This has several important consequences. First, the kernel evaluations are constant along trajectories, instead to be attached to a system state. By doing so, a new ensemble member embedded in the RKHS manifold at the initial time can be very simply estimated at a further time. This framework displays striking properties. The Koopman and Perron-Frobenius operators on such RKHS manifold are unitary, even though the system might be non invertible. They are furthermore uniformly continuous (with bounded generators) and diagonalizable. As such they can be rigourously expended in exponential forms. 

This set of analytical properties enables us to provide a practical estimation of the Koopman eigenfunctions. In the proposed strategy, evaluations of these Koopman eigenfunctions at the ensemble members are exact. To perform robust estimations, the finite-time Lyapunov exponents associated with each Koopman eigenfunction (which are easily accessible on the RKHS manifold as well) are determined. On this basis, we are able to filter the kernel by removing contributions of the Koopman modes that exceed the predictability time. We show that it leads to robust estimations of new unknown trajectories. This framework allows us to write an ensemble-based data assimilation problem, where constant-in-time linear combinations coefficients between ensemble members are sought in order to estimate the QG flow based on noisy swath observations.

The methodology is demonstrated on a barotropic quasi-geostrophic model of a double gyres. After comparing various kernels and provided guidelines to adapt the kernel with the spread of the ensemble, we show isometry and Koopman-filtered reconstructions. Finally, the data assimilation is presented.
Inverting marine terrace morphology to constrain paleo sea-level
Authors: de Gelder Gino , Hedjazian Navid , Pastier Anne-Morwenn , Husson Laurent , Bodin Thomas
Published: March 2022

Quantifying paleo sea-level changes is an important challenge given its intricate relation with paleo-climate, -ice-sheets and geodynamics, but pre-Holocene uncertainties currently span several tens of meters. The world’s coastlines provide an enormous geomorphologic dataset, and recent modelling studies have showed their potential in constraining paleo sea-level through forward landscape evolution modeling. We take a next step, by applying a Bayesian approach to invert the geometry of marine terrace sequences to paleo sea-level. Using a Markov chain Monte Carlo sampling method, we test our model on synthetic profiles and two observed marine terrace sequences. The synthetic profiles – with known input parameters – show that there are optimal values for uplift rate, erosion rate, initial slope and wave base depth to obtain a well-constrained inversion. Both the inversion of synthetic profiles and a terrace profile from Santa Cruz (Ca, US) show how sea-level peaks are easier to constrain than sea-level troughs, but that also solutions for peaks tend to be non-unique. Synthetic profiles and profiles from the Corinth Rift (Greece) both show how inverting multiple profiles from a sequence can lead to a narrower range of possible paleo sea-level, especially for sea-level troughs. This last result emphasizes the potential of inverting coastal morphology: joint inversion of globally distributed marine terrace profiles may eventually reveal not only local relative sea-level histories, but catalyse a better understanding of both global paleo sea-level and glacio-isostatic adjustments.
Do subseasonal forecasts take advantage of windows of opportunity related to a precursor phenomenon?
Authors: Specq Damien , Batté Lauriane
Published: March 2022

This study proposes an objective methodology to highlight windows of opportunity related to a precursor phenomenon in a numerical subseasonal forecasting system. The methodology is based on a contingency table and is illustrated with the relationship between the Madden-Julian oscillation (MJO) and heavy rainfall in the tropical band. As a slowly propagating signal of enhanced convection, the MJO may indicate favorable conditions for heavy precipitation a few weeks ahead in some tropical areas. The combined knowledge of these climatological impacts and the current phase of the MJO at initialization deﬁnes observation-based "climatological windows of opportunity". In a second step, we analyze whether S2S forecasts are indeed more performant when there is increased climatological likelihood of heavy rainfall, i.e whether the forecasts convert "climatological windows of opportunity" into "model windows of opportunity".

The methodology is implemented to the prediction of the upper quintile of weekly precipitation in 20 years of ECMWF S2S reforecasts in the November-to-April season. The ability of the ECMWF forecasts to convert periods with more predictable events into periods of actual forecast skill is only verified for a limited number of small areas, while failures to seize the opportunities lie in misplaced MJO impacts, signal loss or too many false alarms.
A Performance Analysis of the Leica MS60 MultiStation-Based QDaedalus Astrogeodetic Measurement System at the HEIG-VD Test Station, Switzerland
Authors: Albayrak Muge , Willi Daniel , Guillaume Sébastien
Published: March 2022

Since 2014, total station-based QDaedalus astrogeodetic measurement systems have been used to observe astronomical latitudes and longitudes to determine the astrogeodetic deflection of the vertical (DoV). In this study, the Leica Nova MS60 MultiStation-based QDaedalus system’s precision was determined at the HEIG-VD test station, located on the university campus in Yverdon-les-Bains, Switzerland. The data were collected over 13 nights (in an observation period of 44 days from February-April 2021), and comprise 115 series of observations performed over 26 sessions. The term “series” here describes the DoV data obtained during a specified period; QDaedalus observations were executed at ~15 minutes per series, and up to seven series of observations were conducted per session. The standard deviations (SDs) were calculated as 0.11″ and 0.09″ for the N-S and E-W components of the DoV, respectively. The SDs of the results from the HEIG-VD test station show that the N-S DoV components are not as precise as the E-W DoV components. There is a systematic trend in the observed N-S DoV data; the spread of the data in the N-S direction (0.92″) is larger than in the E-W direction (0.71″). The large trend in the N-S direction may be explained by the 0.008″/day trend (0.38″ over the 44-day observation period) in the N-S DoV components; however, this will require further investigation.

This study is the most extensive thus far for determining the precision of the QDaedalus astrogeodetic measurement system. We can conclude that the precisions of the two components lie on the same order of magnitude of 0.1″. These results and the applied method show that the MS60-based QDaedalus system is at least as reliable as the previously-reported total station-based QDaedalus systems. As a result, the MS60-based QDaedalus system can be used effectively in astrogeodetic applications that require high precision. Also, this study demonstrates that astrogeodetic test observations can be conducted at the HEIG-VD test station to determine the precision of newly installed QDaedalus systems.
Present and future tropical fire risks associated with compound events
Authors: Ribeiro Andreia F. S. , Brando Paulo M. , Santos Lucas , Rattis Ludmila , Hirschi Martin , Hauser Mathias , Seneviratne Sonia I. , Zscheischler Jakob
Published: March 2022

Complex interactions between climate and land-use are altering the course of the fire regimes across the tropics. In Brazil, many recent peaks of burned area have co-occurred with extreme climate events, high deforestation rates and agricultural expansion. Particularly during compound dry and hot years, widespread fires have become increasingly common, and an intensification of the fire activity due to climate change may be already underway.

Based on a compound-event-oriented framework to assess fire risk, we provide evidence on the extent to which fire activity and the associated impacts could be constrained if anthropogenic global warming is limited. Here we quantify the nonlinear relationships between compound climate drivers and burned area across two main Brazilian biocultural heritage sites (Xingu and Pantanal) and estimate compound-event-related fire risks in terms of the occurrences of compound drivers beyond which the fire response becomes extreme.

Our results show that the exponential response of burned area to climate is well explained by compound events characterized by air dryness and precipitation deficits (high VPD and low precipitation) and that climate-change induced fire risks will increase due to the co-occurrence of drier and warmer climatic conditions under global warming. However, if global warming is constrained to +1.5°C instead of +3°C, the likelihood of fire risk can be reduced by ~11% in the case of the most prominent fire types (forest fires in Xingu and grassland fires in the Pantanal). We thus conclude that if we slow down the rate of warming and follow more sustainable uses of land, we might be able to prevent the crossing of tipping points and the consequent downward spiral of socio-environmental impacts that threatens these regions.
Weakening of Western Disturbances in Response to Polar Sea Ice Melt
Authors: Chandra Varunesh , Sukumaran Sandeep , Hunt Kieran
Published: March 2022

Arctic sea ice has been declining in recent decades. Further, future projections under strong warming scenarios suggest that sea ice will substantially decline in both poles by the second half of 21st century. The effect of polar sea ice melt on low latitude weather systems is relatively less understood. The changes in equator-to-pole temperature gradient can affect the strength of subtropical jet stream which in turn can modulate transient weather systems such as western disturbances (WDs). WDs play a crucial role in the hydrological cycle of northwestern India and adjoining Himalayan region, so it is essential to know the response of WDs to polar sea ice melt.

     To understand the effects of polar sea ice melt on WD activity, we have run a suite of coupled and uncoupled simulations using NCAR community earth system model (CESM1.2.2). Initially, a control (CTRL) run is performed with the model in a fully coupled configuration for 350 years, with a coarse horizontal resolution (2°x2°). By branching off the CTRL simulation at 300th year, another experiment is carried out in which the albedo of the sea ice is reduced so that the increased absorption of the solar radiation would melt the sea ice. We designate this experiment as sea ice melt experiment (SIME). Transient weather systems may not be adequately resolved in the coarse resolution simulations, so we ran an ensemble of high-resolution Community Atmospheric Model (CAM5) simulations using the sea surface temperature (SST) and sea ice concentration (SIC) annual cycles from the coupled model simulations.

     WDs in the high-resolution CAM5 simulations are tracked using a Lagrangian tracking algorithm. Our analyses reveal that the WD activity weakens in the CAM5 simulations forced with the SST and SIC from SIME experiment. A decrease in the equator-to-pole temperature gradient and a subsequent weakening of the subtropical jetstream were also seen in those simulations.
Global variable-resolution model simulation of rainfall diurnal cycle during boreal summer
Authors: Zhou Yihui , Zhang Yi , Yu Rucong
Published: March 2022

Simulating diurnal cycle of rainfall is a difficult challenge for general circulation models. We developed a global unstructured mesh model, Global-to-Regional Integrated forecast SysTem (GRIST), targeting at unified weather-to-climate forecast. The performance of the model in simulating the summer precipitation over East Asia has been evaluated. Yet the performance from a global perspective remains less understood. In this study, we focus on the simulations of precipitation diurnal cycle during boreal summer, and examine four AMIP simulation results of the GRIST model. These configurations mainly differ in the horizontal resolution. Thus, they reflect the direct changes due to varying resolutions. By refining the resolution over East Asia (VR-EA) and North America (VR-NA) respectively, we analyze the similarities and differences in model behaviors in simulating diurnal cycle of precipitation over these two refinement regions. VR-EA well reproduces the nocturnal rainfall, while VR-NA fails in certain regions respectively. The underlying responses to resolution of these two models are similar. For regions dominated by nocturnal rainfall, the refined resolution significantly increases the composited precipitation intensity at night up to the magnitude of the observation but has little impact on the composite percentage. The percentage of peak rainfall within 00-06h in the model over the Southern Great Plains remains lower than the observation as the resolution refines. Given the much lower occurrence frequency, the contribution of the intense precipitation to the climatological nocturnal rainfall amounts is small in VR-NA. Over East Asia, since the precipitation frequency is comparable to the observation, VR-EA benefits from the increased precipitation intensity due to higher resolution. No apparent artificial features are observed in the transition zone of the variable-resolution mesh. The results suggest that the variable-resolution modeling is cost-effective for simulating the diurnal cycle of climatological summer precipitation.
Slope drivers grain yield in the Yunnan Plateau-Mountain areas
Authors: Qin Yuhong , Rong Li , Duan Xingwu , Gu Zhijia
Published: March 2022

The plateau-mountain areas around the globe are at risk of food insecurity because of its high intensity of soil erosion, limitied suitability of land for agriculture and increasing population pressure. Although plant breeding, improved plant-protection techniques, new variety, application of fertilizer promote increases of crop yields, more frequent extremes of climatic events, topography related to soil erosion can lead to progressive instability in crop production. However little consideration is given in relationships between climatic, topographical factors and grain yields in the Plateau-mountain region. In this study, we collected county-level data on the actual grain yield and environmental factors of the 119 counties in Yunnan province over the past 28 years (1985–2012) to explore the controls on grain yield and how they affect grain yields. Our findings showed that actual grain yeild(AGY) increased over time with an inter-annual fluctuation. Spatially, our findings revealed AGY were strongly influenced by slope. Regression analysis also showed that slope gradient could explain 26.29% of the spatial distribution variability of AGY. Redundancy analysis revealed that AGY positively correlated with evaporation, TN90p, TK, and pH whereas negative correlations with Apre, RH, R50, C/N, slope, and aspect. However climatic and topographic factors and soil properties exhibited greater impacts on AGY, compared to extreme climate indices. We also found that TK showed a significantly positive effect on AGY, indicating that counties with higher TK content in soils could produce higher actual grain yield. And R50 and aspect also had an indirect effect on AGY through influencing TK. Thus, the application of K fertilizer in northwestern, northeastern, and southeastern Yunnan province where soil TK was relatively low may be the key to improve grain yield.
The downward transport of strong winds by convective rolls in a Large Eddy Simulation of Mediterranean cyclone Adrian
Authors: Lfarh Wahiba , Pantillon Florian , Chaboureau Jean-Pierre
Published: March 2022

Windstorms associated with extratropical cyclones belong to the most destructive natural disasters in the mid-latitudes, potentially causing tens of fatalities and hundreds of millions euros in damages yearly. The impact of windstorms is caused by gusts mainly, which arise from the downward transport of strong winds to the surface. The processes leading to the transport of wind gusts are still poorly understood, because they cannot be studied directly due to their short duration and local extent that are too small scale for both observing networks and numerical weather prediction systems.

The opportunity to address this issue arose when the windstorm Adrian (also known as Vaia) occurred over the north-western Mediterranean on 29 October 2018. Although cyclones are usually less intense over the Mediterranean than over the Atlantic, gusts exceeding 180km/h causing several material damages were recorded in Corsica and make Adrian an ideal case study to analyze the transport of strong winds in numerical simulations.

First, we perform a mesoscale analysis of windstorm Adrian, based on simulations on a 1 km grid with Meso-NH. Even at short range <12h, simulations exhibit high sensitivity to the initial conditions and can delay the cyclone by several hours. In a reference simulation, we show that the strongest surface winds occur below the occluded front, and they are due to the cold conveyor-belt (CCB). From the reference simulation, a Large Eddy Simulation (LES) with a horizontal resolution of 200m is performed over a large domain to capture both the mesoscale dynamics and the fine scale characteristics.

Focusing on the LES, we identify two types of strong wind structures: local cells and elongated structures with surface wind speed > 40m/s and duration < 10min. In the strong wind region, boundary layer convection is organised in rolls oriented along the wind direction, with vertical extension and spacing < 1km. It is found only in the convective and unstable boundary layer characterised by moderate surface sensible heat fluxes and vertical wind shear. This suggests that convective rolls are responsible for transporting strong winds to the surface. To ensure that, passive tracers initiated in the CCB region are computed to illustrate the way strong winds are transferred downward. Subsequently, a detailed study of the turbulent fluxes at the air-sea interface is carried out to evaluate their role in the transport of winds in the atmospheric boundary layer. It shows the influence of the various processes considered in the parameterisations of surface fluxes on the presence and intensification of the convective rolls.

The results show, using the LES, that the downward transport of strong winds in the cold conveyor-belt of Adrian is caused by small-scale convective rolls.
Modeling of hydroxyl oxidation and wet deposition in volcanic sulfur dioxide plumes: the July 2018 Ambae eruption
Authors: Liu Mingzhao , Griessbach Sabine , Hoffmann Lars
Published: March 2022

Sulfur dioxide (SO2) is one of the most abundant gases released by volcanic eruptions. It is of concern due to its potential to influence climate on the global scale. Next to advection and diffusion, various chemical and geophysical processes need to be considered to properly represent volcanic SO2 plumes in Lagrangian transport simulations. The chemical reaction of SO2 with the hydroxyl radical (OH) and wet deposition are major processes depleting SO2 from volcanic plumes. In this study, we implemented and revised new modules for OH chemistry and wet deposition in the Massive Parallel Trajectory Calculations (MPTRAC) Lagrangian transport model. In MPTRAC, the OH chemistry module adopts the newest JPL data evaluation to calculate the temperature- and pressure-dependent reaction coefficient of the termolecular reaction of SO2 and OH. Similar to other Lagrangian chemistry transport models, monthly mean zonal mean OH fields are applied in the MPTRAC simulations. However, here we propose to introduce a correction factor depending on the solar zenith angle in order to represent the diurnal variations of the OH concentrations. The wet deposition module of MPTRAC mainly uses cloud ice and liquid water content retrieved from ECMWF’s meteorological data as well as an effective Henry constant, considering both, the dissociation and dissolution of SO2 in cloud water. The revised and improved MPTRAC model is evaluated in the case study on the July 2018 eruption of Ambae, Vanuatu, the most voluminous volcano of the New Hebrides archipelago. It is reported that during the eruption, the island of Ambae suffered from acid rain, which means that the volcanic plume encountered clouds and significant wet deposition of SO2 due to precipitation. A series of sensitivity tests was conducted to assess the two new chemistry modules of MPTRAC. An inspection of the time series of SO2 total mass revealed that the diurnal variations due to the OH chemistry are now properly represented in the model. The trajectories of the SO2 parcels have large influence on the wet deposition because they determine whether they pass through cloudy regions or not at a certain time and location. Therefore, it is important to use the most accurate meteorological data and source information. With the revised MPTRAC model, we found that a significant part of the loss of SO2 total mass from the Ambae eruption is represented in the simulations. However, satellite observations reveal even shorter tropospheric lifetimes of the volcanic SO2 plume from the Ambae eruption, which indicates that future work needs to focus on including additional chemical and geophysical processes in the simulations.
Forecasting high resolution variations in deep geothermal wells based on low resolution measurements utilizing virtual sensors
Authors: Dietmaier Annette , Baumann Thomas
Published: March 2022

Multiple operators use geothermal wells in Lower Bavaria and Upper Austria for balneological (medical and wellness) applications and for energy and/or heat mining purposes. These applications depend heavily on the well‘s hydrochemical and geophysical stability (mineralization, pressure, temperature).

At the moment, wells are submitted to inspection once a year, which includes the analysis of ions, pH, pressure, temperature etc. These „offline“ analyses, while covering a large set of parameters, obviously fail to show intra-annual variability within the measured parameters. On the other hand, some geothermal wells are being monitored quasi-continually. These „online“ sensors, however, only cover a small set of selected parameters, such as electric conductivity, temperature and pressure.

This study aims at forecasting hydrochemical and physical stability based on annual measurements by assessing the degree of intra-annual variability covered or neglected by the yearly measurements. The results are required for a sound assessment of possible adverse effects of other exploration activities and short term variations of the withdrawal rates reflecting the demand for heat, energy and/or spa water. To do this, we followed the concept of virtual sensors and their correlation to detailed yearly measurements.

We found that, while annual measurements, when taken approximately in the same season of the year, do match the data sampled online quite well, intra-annual variability at the examined wells was quite strong for some parameters and not represented by the offline data. Thus, annual data can be used to make predictions regarding long-term variability. In order to forecast intra-annual variability, higher temporal resolution is necessary. While not a replacement for the detailed analyses, the virtual sensors presented here provide a robust method to trigger further actions.
The spatial-temporal patterns of East Asian climate in response to insolation, CO2 and ice sheets during MIS-5
Authors: Lyu Anqi , Yin Qiuzhen
Published: March 2022

Marine Isotope Stage (MIS) 5, between about 130 and 70 ka BP, is a relatively long warm period characterized by climate oscillations consisting of three interstadials and two stadials. In this study, two sets of snapshot simulations by a step of 2 ka covering the whole MIS-5 period are performed with the model HadCM3 to investigate the relative impacts of insolation, CO2 and Northern Hemisphere ice sheets on the internal variations within MIS-5 and spatial variations of the East Asian climate, including the East Asian summer monsoon (EASM) intensity. The first set of experiments are forced by varying insolation and GHGs (OrbGHG) and the second ones are forced by varying insolation, GHGs and ice sheets (OrbGHGIce). Results show that a similar trend with precession can be found in the simulated summer precipitation, temperature and EASM index in both OrbGHG and OrbGHGIce, indicating the dominant role of precession on the EASM. Within the range of CO2 variability during MIS-5, the change of CO2 causes similar degree of warming effect, but much lower degree of humidifying effect compared to insolation. Insolation and CO2 change the precipitation through different dynamic and thermodynamic processes. Our results also show that the influence of ice sheets on temperature and precipitation is less important than the effect of insolation and it varies from regions and in time. The effect of ice sheets depends on background insolation and also the location, height and area of ice sheets. The simulated spatial-temporal variations of the EASM climate are compared with proxy records and the mechanisms involved are investigated. 
The zeta potential of quartz. Surface complexation modelling to elucidate high salinity measurements
Authors: Leroy Philippe , Li Shuai , Maineult Alexis , Vinogradov Jan
Published: March 2022

The zeta potential is a measureable electrical potential of paramount importance to understand the electrochemical properties of colloids and grains in contact with brines. However, the zeta potential remains poorly understood because it takes place at the nanoscale of the electrical double layer on the mineral surface. Streaming potential measurements on quartz-rich Fontainebleau and Lochaline sandstones carried out at high salinity (above 0.1 M NaCl) yield surprisingly high zeta potential values. We found that placing the shear plane, where the zeta potential is defined, slightly closer to the mineral surface than the outer Helmholtz plane significantly improves the predictions of the zeta potential and surface charge density of quartz at high salinity as well as the values of the equilibrium constant describing sodium adsorption in the Stern layer. Our results have strong implications for the modelling of the electrochemical properties of minerals in contact with highly saline solutions.
A lumped parameter modeling approach considering land-cover and land-use for the simulation of karst spring hydrological functioning.
Authors: Sivelle Vianney , Jourde Hervé , Bittner Daniel , Richieri Beatrice , Labat David , Hartmann Andreas , Chiogna Gabriele
Published: March 2022

The lumped parameter modeling approach has been widely applied in karst hydrology for, among other applications, the understanding of their functioning of the assessment or groundwater availability in a context of global change. Nonetheless, such an approach generally does not account for land-cover land-use (LCLU) changes and their potential impacts on recharge processes. The study focuses on three forests dominated karst catchments: Kerschbaum (Lower Austria), Baget (French Pyrenees) and Oeillal (southern France), and investigates how LCLU changes in a lumped parameter modeling approach can affect both the internal fluxes and the model performance. The active subspace method is used to perform sensitivity analysis of model parameters, and to quantify parameter uncertainty. We show that the consideration of a semi-distributed recharge constitutes a relevant approach to capture the impact of LCLU changes on flow dynamics, but also introduces more uncertainty in the modeling approach. This approach may thus allow identifying the trade-off between modeling approach complexity and its performance. Finally, it gives new insight for the assessment of LCLU changes impacts on karst groundwater resource.
Alfvénicity of velocity and magnetic field Increments Observed by Parker Solar Probe
Authors: Thepthong Panisara , Pongkitiwanichakul Peera , Ruffolo David
Published: March 2022

Alfvénicity is a well-known property of the solar wind. The magnetic and velocity fluctuations are highly correlated over much of the region between the Sun and the Earth. The Parker Solar Probe (PSP) spacecraft enables us to probe Alfvénicity closer to the Sun than before. One previous finding is that the Alfvén ratio increases as the scales become smaller, as shown in some works by using Fourier analysis. This work measures Alfvénicity from PSP observations using 2nd-order structure functions and other quantities derived from magnetic and velocity increments as functions of time lag. We introduce a method to subtract noise from the velocity structure function. We also provide the relation between a time lag in our work and the frequency that contributes most to the 2nd-order structure function for such a time lag. This relation allows a direct comparison between functions of time lag and Fourier spectra. This research has been supported in part by grant RGNS 63-045 from Office of the Permanent Secretary, Ministry of Higher Education, Science, Research and Innovation, and by grant RTA6280002 from Thailand Science Research and Innovation.
Flood Risk Evaluation in Lebanon Based on Newspaper Records
Authors: Hdeib Rouya , Abdallah Chadi , Colin François , Moussa Roger
Published: March 2022

Flood mitigation planning requires the proper estimation of the flood risk. When systematic gauging of floods is short or lacking interesting information can be inferred from historical flood records in newspapers. We present the work to locate and evaluate past flood information recorded in newspapers to collate a national flood database for Lebanon and to evaluate the consequent flood risk. Over 700 records of flood events were extracted from newspapers and implemented in a GIS database. The spatial occurrence of these events was studied and linked to a combination of morphological, hydrological, and vulnerability characteristics of the major Lebanese catchments. Accordingly, a flood risk map was developed for the country. In this study, we show that retrieving newspaper information on previous floods was an added value and was beneficial in evaluating flood risk on a national scale.
High-resolution water table depth modelling of Danish peatlands for upscaling emission of greenhouse gases
Authors: Koch Julian , Gyldenkærne Steen , Greve Mogens Humlekrog , Elsgaard Lars , Stisen Simon
Published: March 2022

Water table depth (WTD) modulates greenhouse gas (GHG) emissions from drained peatland soils and rewetting peatlands has been identified as a cost-effective mitigation measure to reduce emissions from the agricultural sector. However, detailed knowledge of the spatial variability of WTD is needed to guide the planning of rewetting measures as well as to upscale GHG emissions from peatlands for national inventories. In this study we developed a high-resolution (10 m) map of long-term mean summertime WTD for Danish peatlands (~9,000 km2) using a gradient boosting decision tree algorithm. The machine learning (ML) model was trained against more than 10,000 WTD observations as well as water levels in over 10,000 groundwater connected lakes and rivers. The WTD observations were transformed to better account for the non-linear relationship between WTD and GHG emissions and the limited WTD range (such as 0 – 50 below ground) in which GHG emissions are most sensitive. Over 20 high-resolution explanatory variables, many of which are satellite based, provided diverse information on topography, groundwater, moisture conditions, land-use and geology to the model. Cross validation was applied to evaluate the accuracy of the trained ML model with special focus on the shallow WTD (mean error= -8cm and mean absolute error = 18 cm). The horizontal and vertical distance to the nearest waterbody as well as organic content of the soil and land surface temperature were among the most important explanatory variables of the trained ML model. The WTD map was subsequently applied as input to two recently developed WTD-dependent GHG emission models to upscale GHG emissions from Danish peatlands. For this purpose, the mean summertime WTD map had to be corrected to represent mean annual conditions. Lastly, simple rewetting scenarios, i.e. decrease in WTD, were applied to elucidate the potentials of rewetting as mitigation measure.         
Overturning and Water Mass Transformation in the Subpolar North Atlantic
Authors: Jackson Laura
Published: March 2022

The Atlantic Meridional Overturning Circulation (AMOC) influences our climate by transporting heat northwards in the Atlantic ocean. The subpolar North Atlantic plays an important role in this circulation, with transformation of water to higher densities, deep convection and formation of deep water. Recent OSNAP observations and observations of surface flux driven water mass transformation have shown that the overturning is stronger to the east of Greenland than the west.

Firstly we analyse a CMIP6 climate model at two resolutions (HadGEM3 GC3.1 LL and MM) and show both compare well with the OSNAP observations. We explore the source of low frequency variability of the AMOC and how it is related to the surface water mass transformation in different regions. We then use a set of CMIP6 climate models and show that most climate models agree with the observations that overturning in the west is small, and show biases in the overturning in the west are related to biases in temperature and salinity. We also investigate low frequency variability and find a range of behaviour.