bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelling of emergencies on transportation system in the context of climate change
Authors: Wang Weiping
Published: February 2023

Current effects of emergencies on human be amplified as extreme weather and outbreaks of epidemic disease increasing. The transport system is crucial for daily life and threatened heavily by these emergencies. Despite advances in emergency management for transportation, we still lack an integrated framework to examine the impact of transport system under different types of extreme event.First, we develop a failure model to study the effect of floods on road networks; the result covers 90.6% of road closures and 94.1% of flooded streets resulting from Hurricane Harvey. We study the effects of floods on road networks in China and the United States, showing a discontinuous phase transition, indicating that a small local disturbance may lead to a large-scale systematic malfunction of the entire road network at a critical point.Second, we propose an integrated approach to quantitatively assess how floods impact the functioning of a highway system. This approach is illustrated with a case study of the Chinese highway network. The results show that or different global climate models, the associated flood damage to a highway system is not linearly correlated with the forcing levels of RCPs, or with future years.Finally, we propose an analysis framework combining with Simulation of Urban Mobility (SUMO) simulator to evaluate the impact of the road transport system within an urban agglomeration from the views of structure and function under four types of emergencies: natural disaster, traffic accident, public health event and social security incident. Guangdong-Hong Kong-Macao Greater Bay Area (GBA) is one of the regions with the highest degree of openness and the strongest economic vitality in China, with convenient transportation conditions. This method is applied to a case study of the GBA urban agglomeration in China. These results have critical implications for transport sector policies and can be used to guide highway design and infrastructure protection. These approaches can be extended to analyze other networks with spatial vulnerability, and it is an effective quantitative tool for reducing systemic disaster risk.
Interactions between wind waves and frazil ice in the turbulent surface boundary layer of an Antarctic coastal polynya
Authors: Herman Agnieszka , Bradtke Katarzyna
Published: February 2023

Coastal (latent heat) polynyas are regions of extremely strong ocean–atmosphere heat, moisture and momentum exchange, often with wind speed and surface turbulent heat flux exceeding 30 m·s–1 and 1000 W·m–2, respectively, and air temperature below –20°C. Consequently, polynyas play a very important role in shaping the local and regional weather, are crucial for sea ice production and the associated formation of dense water masses. The ocean mixed layer (OML) during polynya events is highly turbulent, with turbulent dissipation due to wind shear, waves and convective mixing. Crystals of frazil ice forming in those very dynamic conditions are transported throughout the OML along irregular, three-dimensional trajectories. The manifestation of those processes at the surface are characteristic elongated strips with high frazil concentration – so called frazil streaks – forming in convergence zones of the Langmuir circulation (https://egusphere.copernicus.org/preprints/2022/egusphere-2022-1435/). The presence of frazil streaks and open water areas between them leads to high spatial variability of OML and, crucially, sea surface properties. In particular, the bulk water viscosity within streaks is much higher and the sea surface roughness much lower than in open water. This in turn affects the momentum flux from the atmosphere and the evolution of wind waves. Wave breaking is suppressed, and short waves are dissipated by frazil/grease ice. Therefore, the whole spectral energy balance is modified. In this paper, satellite data and spectral wave modelling are used to analyse fetch-limited, deep-water wave growth during selected polynya events in the Terra Nova Bay, Antarctica. It is shown that wave growth in the presence of frazil streaks is slower than in analogous ice-free situations, and that wave–ice interactions are the only plausible explanation for observations. Simulations with a spectral wave model SWAN (Simulating Waves Nearshore) are used to examine different scenarios of how the source terms related to wind input, quadruplet wave–wave interactions, whitecapping, and dissipation in grease ice contribute to the net wave energy growth with distance from shore. Additionally, the role of across-wind variations of wind speed and wave properties is examined in detail, illustrating the inherently two-dimensional character of the polynyas’ wave field. Overall, the study shows that polynya events provide a unique, very valuable setting for studying wave–ice interactions, in many respects fundamentally different from the ‘standard’ case of swell entering the marginal ice zone from the open ocean.
A Temperature-Duration-Curve model for the real-time estimation of extreme river water temperatures at ungauged sites
Authors: Ouarda Taha , Charron Christian , St-Hilaire André
Published: February 2023

Water temperature is an important environmental variable that has impacts on the physical, chemical, and biological processes in streamflows. Extreme river water temperatures affect the spawning, development and survival of several fish species, and are considered as important indicators of the health of a river and essential variables in all habitat models. Unfortunately, river water temperature data is characterised by its limited availability: measurement sites are often scarce, and records are regularly very short when available. It is hence crucial to develop regional thermal data estimation models for ungauged and partially gauged locations. Very few studies in the literature focused on the estimation of extreme water temperatures at sites where thermal data are limited or inexistent. A Temperature-Duration-Curve (TDC) model is proposed in this work to provide real-time estimates of river water temperature at ungauged locations during extreme events. The TDCs are estimated at the ungauged locations using a Generalised Additive Model and are then used to provide continuous estimates of river water temperature at these sites based on a spatial interpolation model. The model is developed based on a data base of 126 river thermal stations from Canada. The performance of the method is compared to a simpler approach and results indicate that the developed TDC model is robust and useful in practice.
The necessary ingredients for deterministic modelling of hydropower management and climate change impacts on stream temperature in peri-Alpine streams
Authors: Dorthe David , Pfister Michael , Lane Stuart N.
Published: February 2023

The thermal regime of regulated rivers is altered by rapid discharge variation downstream of hydropower plants (hydropeaking). This strongly modifies the thermal regime of such rivers, due to both the upstream water storage and the associated regular release to downstream, resulting in a thermal wave as the water temperature is different from the river temperature (thermopeaking). This temperature alteration needs to be considered when managing hydropower installations because of its influence on the health of aquatic ecosystems. On a longer timescale, global climate change is also influencing the natural thermal regime of rivers through changes in air temperature, vegetation, hydrology, etc. Thus, the assessment of the effects of hydropower on streams needs also to consider the extent to which changing climate will modify existing hydropower impacts, and also the mitigation methods that have been developed for current climate situations.To evaluate the evolution of river temperature under different scenarios, deterministic coupled, hydrodynamic and temperature modelling can be used. Such models have been used previously to replicate the thermal regime of rivers or evaluate the impact of climate change on river temperature. However, there is a growing realisation that external drivers of stream temperature are more complex than hitherto thought, especially in per-Alpine streams. For instance, such streams can have significant shading whose importance changes as a function of time within the year. Equally, between the zone of water off-take and return, the residual flow may not occupy the full channel perimeter meaning that it is also necessary to consider the energy balance effects of water-adjacent sediments.To address this challenge this paper identifies the necessary ingredients of deterministic coupled hydrodynamic and temperature modelling for hydropower impacted streams. This is supported by a unique and very high-quality stream temperature dataset which we use to identify the minimum process representation required for such models. In order to reproduce such data, we show that such models need to have a spatially-explicit and time-dependent correction of two key processes: (1) solar shading; and (2) stream bed sediment effects.
Effects of pedon-scale soil heterogeneity on soil temperature and surface energy fluxes - Does it matter?
Authors: Thurner Melanie A. , Rodriguez-Lloveras Xavier , Beer Christian
Published: February 2023

Soil texture, i.e. its composition of clay, silt and sand, as well as organic material, is often very heterogeneous within small distances. State-of the-art land-surface models usually cannot capture this due to their coarse grid. However, neglecting small-scale soil heterogeneity may affect the estimated exchange of energy, water, and carbon between land and atmosphere strongly.This discrepancy is especially problematic when modelling permafrost soils, where the heterogeneity-induced mismatch can make the difference between frozen and unfrozen soil, as well as waterlogged and unsaturated soil, as soil texture determines physical properties such as heat and water-storage capacity. By that, soil heterogeneity affects the build of soil ice and resulting frost heave, determines pond locations, and ultimately influences soil genesis, e.g. by inducing cryoturbation. The determination of soil geophysics also propagates into biogeochemical dynamics, affecting the arctic carbon cycle by providing the environment for either carbon stabilization or degradation. To assess the effect of soil heterogeneity in detail, and quantify the potential mismatch, we develop a two-dimensional geophysical soil model with a spatial resolution of less than 10 cm at the region of interest. We apply our model at permafrost sites, because our ultimate aim is to understand cryoturbation as a permafrost-specific soil process and its relevance for the arctic carbon cycle, which will finally allow us to improve predictions of the Arctic carbon budget.Here we present our first results, where we study the effect of fine-scale soil heterogeneity on soil temperature, water, and implications for the simulated sensible and latent heat fluxes between soil and atmosphere. By comparing simulations with and without soil texture heterogeneity, as well as with and without lateral fluxes of heat, we are able to quantify the effect of soil heterogeneity at small scale and discuss the effect on larger scales.
Novel insights into aerosol-cloud interactions enabled by analysing the temporal evolution of strong anthropogenic cloud perturbations
Authors: Rahu Jorma , Toll Velle
Published: February 2023

Anthropogenic aerosol particles affect clouds by serving as cloud condensation nuclei, thus significantly influencing Earth’s energy balance. The magnitude of aerosol-induced changes in cloud properties is still uncertain. This is primarily due to the meteorological covariability between aerosols and clouds, which hinders inferring causal relationships. Industrial air pollution sources serve as natural experiments to study strong anthropogenic cloud perturbations (Toll et al. 2019 Nature https://doi.org/10.1038/s41586-019-1423-9) and allow us to infer causal relationships between aerosols and clouds. We use geostationary satellite observations to study the temporal evolution of polluted clouds. Polluted clouds are usually thinner than nearby unpolluted clouds. But in some cases, the polluted clouds grow much thicker in the afternoon than the nearby unpolluted clouds. We find that continental polluted cloud tracks are relatively long-lived, with a median lifetime of 18 hours. Moreover, there are many cases where polluted cloud tracks are visible for multiple consecutive days. This means polluted cloud tracks live long enough for clouds to fully adjust to aerosol-increased cloud droplet numbers. Future work is needed to combine geostationary and polar orbiting satellite observations of polluted cloud tracks to develop stronger observational constraints for aerosol-cloud interactions.
Precursor of disintegration of Greenland's largest floating ice tongue
Authors: Humbert Angelika , Helm Veit , Neckel Niklas , Zeising Ole , Rückamp Martin , Shfaqat Abbas Khan , Erik Loebel , Gross Dietmar , Sondershaus Rabea , Müller Ralf
Published: February 2023

The largest floating tongue of Greenland’s ice sheet, Nioghalvfjerdsbrae, has so far been relatively stable with respect to areal retreat. Curiously, it experienced significant less thinning and ice flow acceleration than its neighbour Zacharias Isbrae. Draining more than 6% of the ice sheet, Nioghalvfjerdsbrae might become a large contributor to sea level rise in the future. Therefore, the stability of the floating tongue is a focus of this study. We employ a suite of observational methods to detect recent changes. We found that the calving style has changed at the southern part of the eastern calving front from normal tongue-type calving to a crack evolution initiated at frontal ice rises reaching 5-7km and progressing further upstream compared to 2010. The calving front area is further weakened by a substantial increase of a zone of fragments and open water at the tongue’s southern margin, leading to the formation of a narrow ice bridge. These geometric and mechanical changes are a precursor of instability of the floating tongue. We complement our study by numerical ice flow simulations to estimate the impact of future break-up or disintegration events on the ice discharge. These idealised scenarios reveal that a loss of the south-eastern area would lead to 1% of increase of ice discharge at the grounding line, while a sudden collapse of the frontal area (46% of the floating tongue area) will enhance the ice discharge by 8.3% due to loss in buttressing.Humbert, A., Helm, V., Neckel, N., Zeising, O., Rückamp, M., Khan, S. A., Loebel, E., Gross, D., Sondershaus, R., and Müller, R.: Precursor of disintegration of Greenland's largest floating ice tongue, The Cryosphere Discuss. [preprint], https://doi.org/10.5194/tc-2022-171, in review, 2022
Threefold reduction of modeled uncertainty in direct radiative effects by constraining absorbing aerosols over biomass burning regions
Authors: Zhong Qirui , Schutgens Nick , van der Werf Guido ,   AeroCom modelers
Published: February 2023

Absorbing aerosols emitted from biomass burning play an essential role in affecting the radiation balance, cloudiness, and atmospheric circulation over tropical regions. Assessments of these impacts rely heavily on the modeled aerosol absorption from poorly constrained global models and thus exhibit large uncertainties. By combining the AeroCom global model ensemble with satellite and in situ observations, we provide new constraints on the aerosol absorption optical depth (AAOD) over the Amazon and Africa. Our approach enables identifying, for each model, error contributions from emission, lifetime, and MAC (mass absorption coefficient), with emission and MAC dominating the modeled AAOD errors. In addition to primary emissions, we quantify substantial formation of secondary organic aerosols over the Amazon but not over Africa, which potentially contributes to the modeled AAOD errors. Furthermore, we find that discrepancies in the direct aerosol radiative effects between models decrease by threefold after correcting for the identified errors. This demonstrates that our work can significantly reduce the uncertainty in aerosols, which are considered the most uncertain radiative forcing agent.
On the development of a hybrid sea-ice model by combining particle and continuums mechanics
Authors: Kahl Saskia , Mehlmann Carolin
Published: February 2023

Currently climate models represent sea ice by a continuums approach. The continuums assumption implies that statistical averages can be taken over a large number of floes.  But the application of continuum rheological models at or below the scale of individual floes is only appropriate if the mode of failure of a single floe is the same as the mode of failure of an aggregate of floes. Continuum models have been developed for a grid resolution of 100 km. In last years computing power has increased and sea-ice models are often run at high mesh resolutions where a grid cell may no longer contain a representative sample of sea-ice floes.We are addressing these shortcomings of current continuum sea-ice models by developing a hybrid model. The idea of the hybrid approach is to nest a Discrete Element Model into a continuum sea-ice model in order to predict sea ice on fine spatial scales in a region of interest. To facilitate the coupling between the continuum and Discrete Element Model a Particle-in-Cell scheme is used which ensures mass conservation in the hybrid approach. We analyze the coupling of the continuums and particle mechanics and discuss the advantages and disadvantages of this approach.
Assessment of long-time series of soil water content through an innovative robust statistical model
Authors: Sannino Giada , Anello Mirko , Riani Marco , Laurini Fabrizio , Bittelli Marco , Bordoni Massimiliano , Meisina Claudia , Valentino Roberto
Published: February 2023

The aim of this research is testing a new statistical model able to describe the interaction between soil and atmosphere. The model is based on a robust parametric LTS (Least Trimmed Squares) method and harmonic functions. It has been developed taking into account field measurements of quantities involved in both infiltration and evapo-transpiration phenomena, such as volumetric water content, soil-water potential, air temperature, rainfall amounts and solar radiation. The proposed statistical model allows assessing the volumetric water content at different sites using only time series of daily rainfall amount as input data. The model was applied in different test sites, whose data were assumed by the International Soil Moisture Network (ISMN). In fact, ISMN allows getting free time series of soil and meteorological data from monitoring stations all over the world. This note shows how the proposed model is accurate with respect to field data in estimating the volumetric water content in different soils, climates and depths. Future implications of this research will regard water content predictions, especially in areas where field data are scarce. Since the proposed LTS algorithm is very efficient and the computational workload is rather low, the possibility of coupling it with a slope stability analysis over large areas will be investigated, in order to get a distributed real-time model for shallow landslides susceptibility.
Can cup-plant (Silphium perfoliatum L.) as a perennial bioenergy crop surpass silage maize (Zea mays L.) for C sequestration?
Authors: Abdalla Khatab , Pausch Johanna
Published: February 2023

Intensified silage maize (Zea mays L.) cultivation has led to several environmental problems such as high greenhouse gas emissions and groundwater pollution, thus further amplifying climate change. Therefore, alternative crops with high carbon (C) sequestration capacities are crucial for sustainable bioenergy production, particularly those that can cope with extreme climate events, such as drought stress. Therefore, this study aimed to evaluate the potential of the perennial cup-plant (Silphium perfoliatum L.) as a promising alternative for silage maize to increase soil C input and reduce C output (as CO2) under optimum watering and drought conditions. For this purpose, a lysimeter experiment comparing these crops subjected to two watering regimes (well-watered and drought-stressed), was set up at the botanical garden of the University of Bayreuth, Germany. Soil respiration was correlated to soil moisture and temperature, biomass (aboveground and belowground), soil C and nitrogen (N), and dissolved organic C (DOC) and inorganic C in the leachates. Soil CO2 efflux was measured using a Licor-6400XT gas exchange system (LI-COR, Lincoln, NE, USA)) fitted with a soil chamber over three consecutive years. The final cumulative CO2 efflux was greater by 29% under drought-stressed cup-plant than in drought maize, which was explained by the greater belowground biomass production under cup-plant. Cup-plant increased root biomass by 143% (0.86±0.26 vs 2.08±0.33 kg m-2) compared to silage maize, thus, implying a higher contribution of root respiration to the total soil respiration under cup-plant. Despite the soil respiration and DOC leaching being higher for cup-plant than maize, cup-plant increased soil C (by 4%) and N content (by 14%), after only two years of cultivation. Even though root respiration and enhanced microbial activity result in higher soil respiration and C mineralization, the continuous supply of fresh C via the root litter and rhizodeposits of the perennial cup-plant suggests long-term effective C farming and demonstrates the potential of the cup-plant as an ecological alternative to silage maize.Keywords: Climate change; soil respiration; carbon sequestration; bioenergy crops; leachates 
Summarizing the research of the MADEIRA project - Middle atmosphere dynamics: exploiting infrasound using a multidisciplinary approach at high latitudes
Authors: Näsholm Sven Peter , Amezcua Javier , Assink Jelle D. , Belova Evgenia , Blixt Erik Mårten , Brissaud Quentin , Eggen Mari Dahl , Espy Patrick J. , Hibbins Robert , Kero Johan , Kvaerna Tormod , Le Pichon Alexis , Orsolini Yvan J. , Vera Rodriguez Ismael , Turquet Antoine , Vorobeva Ekaterina
Published: February 2023

The MADEIRA project (Middle Atmosphere Dynamics: Exploiting Infrasound Using a Multidisciplinary Approach at High Latitudes) is a four-year basic research project finishing in the spring 2023, funded by the Research Council of Norway. Its primary objective has been in elucidating the 30-60 km altitude range over large spatial scales using wind and temperature constraints from infrasound data collected at Arctic stations. Wave propagation modelling and infrasound interpretation from well-characterized sources provide remote atmospheric sensing. These data are more continuous in space and time than from many other direct measurement techniques. An aim has been to constrain high-top atmospheric models and explore stratosphere-mesosphere coupling with meteor radar wind measurements sampling the 70-100 km altitude range in combination with the infrasonic data. Another ambition has been to develop real-time diagnostic tools for the stratospheric polar vortex circulation and extreme events like Sudden Stratospheric Warmings. Thanks to this project, the research teams have got the opportunity to explore several aspects and building blocks related to infrasound-based middle atmospheric probing and to work towards an assimilation of such datasets into atmospheric models. This paper reviews key research output from the project and highlights accomplishments in the domains of, e.g.: Tropospheric and stratospheric cross-wind estimation using infrasound from explosions; Assimilation of atmospheric infrasound data to constrain tropospheric and stratospheric winds; Atmospheric wind and temperature profile inversion in an ensemble model context; Microbarom radiation and propagation model benchmarking; Speeding up infrasound transmission loss estimation using deep learning; Probing internal middle atmospheric gravity waves; Using a machine learning and stochastics-founded model to provide near real-time stratospheric polar vortex diagnostics. This project has included several high risk / high gain components and we highlight results that maybe could be labelled as unexpected successes, but we also discuss challenging research obstacles that occurred in our journey.
The use of cost-effective GNSS units as a volcano monitoring tool on Saba, Caribbean Netherlands
Authors: Krietemeyer Andreas , de Zeeuw-van Dalfsen Elske , Sleeman Reinoud
Published: February 2023

We present initial positioning results obtained by analyses of data from four cost-effective Global Navigation Satellite System (GNSS) units installed on the island of Saba. The island hosts the active but quiescent stratovolcano Mt. Scenery which reaches an elevation of 887 metres and was last active around 1640. The cost-effective GNSS units were installed around the volcano in February 2022 and house all necessities for autonomous, continuous monitoring. The overall equipment cost per unit is about 1000 Euros, a fraction of the material costs of a conventional, permanent continuously monitoring GNSS station. Furthermore, the typical installation time of permanent stations takes multiple days whereas the installation time required for our cost-effective units can be undertaken within a few hours. We demonstrate that the performance of the cost-effective GNSS units for daily positioning estimations is comparable with the performance of permanent stations. We investigate the precision and accuracy of the time series of kinematic and static positioning solutions using geodetic positioning estimation algorithms. For direct comparison we placed one cost-effective GNSS unit next to a permanent, conventional GNSS station. Furthermore, we investigate if results improve after applying a minimum-effort calibration of the cost-effective antenna using a permanently installed GNSS station. We demonstrate that cost-effective GNSS units are i) well-suited to extend an existing volcano monitoring network of permanent GNSS stations and ii) can potentially even be used independently for basic volcano monitoring when funding is limited. We also envisage the use of cost-effective GNSS units for rapid deployment in hazardous or risk-prone areas where installations of conventional GNSS stations could be deemed too costly.
Studying renewable energy generation variability under future climate scenarios in Chile
Authors: Valenzuela-Venegas Guillermo , Zeyringer Marianne
Published: February 2023

Chile has proven to be a country with great potential for renewable energies, favoring in the last decades the development of renewable energy projects, increasing its solar and wind capacities from 202 MW (1.1%) in 2012 to 6522 MW (21%) in 2021, and increasing further by 2022 to a total of 10476 MW (32%). According to the Chilean Energy Ministry, this trend will continue to increase to cover 70% of energy generation by 2030 with renewable energy sources and to meet the carbon neutrality scenario by 2050. However, since the electricity generation from renewable energy sources is affected by future extreme weather events caused by climate change, this possible uncertainty and variability should be considered when new energy projects are designed and developed. The present work aims to study the variability of renewable energy generation under future climate scenarios in Chile.To capture the future variability of the weather conditions, we use the global climate models from Coupled Model Intercomparison Project Phase 6 (CMIP), which assess future climate change projections considering climate variability and uncertainties scenarios. We adapt these datasets for Chile, interpolate the wind speed based on model-level raw data proposed by Hahmann et al., and calculate capacity factors per renewable technology.Through this study, we expect to explore the changes in renewable energy generation in Chile, estimating the impact of climate changes in this area. This work will help decision-makers decide on the future energy transition of Chile in the face of extreme changes in the climate condition of the country.
Comparison of the energy fluxes inferred from eddy covariance and optical scintillometer at the agricultural field during different parts of the season
Authors: Orság Matěj , Fischer Milan , Pozníková Gabriela , Eitzinger Josef , Trnka Miroslav
Published: February 2023

This study summarizes seasonal monitoring of turbulent energy fluxes from eddy covariance (EC) and large aperture optical scintillometer, measuring in parallel. The site (agricultural field of app. 16.5 ha) is located in north-eastern Austria, Danube river lowland (48.21N, 16.622E); in 2019 covered subsequently by a winter wheat field, straw, and bare soil. The EC together with ancillary measurement was located at the 2.7 m height at the center of the field. The radiation balance components measurements consist of a 4-channel net radiometer for net radiation (Rn) installed at 3.5 m and three soil heat flux plates for soil heat flux (G) monitoring (0.05 m below surface), including thermocouples for quantification of the heat storage above the soil heat flux plates. The scintillometer transmitter and receiver units were fixed at 4 m height masts, facing towards each other from the NW and SE corners of the field, with a measurement path length of 570 m diagonally across the field. The EC method enables the determination of fluxes within a footprint centered around the point of measurement in the middle of the field, whereas the scintillometer provides an estimation of sensible heat flux (HSC), derived from air refractive index fluctuation integrated over the measurement path length. The scintillometer-based latent heat (LESC) is calculated as a residuum from available energy (Rn-G) and HSC, provided by the scintillometer. As the EC method provides direct measurements of sensible heat (HEC) and latent heat (LEEC) fluxes we use it as a reference method. During the period March to June (green canopy) the comparison of the EC-based turbulent fluxes (HEC+LEEC) and the available energy (Rn-G) showed a very good agreement, resulting in the energy balance closure of 0.97 (R2 = 0.94). This suggests the ability of the EC method to capture all scales of eddies responsible for energy transport at this site as well as the good accuracy and robustness of the measurement setup. During the period March to June (green canopy), the HEC, LEEC, HSC, and G fluxes accounted for 23 % (R2 = 0.55), 60 % (R2 = 0.72), 32 % (R2 = 0.56), and 12 % (R2 = 0.62) of the Rn flux, respectively. The comparison of methods indicates that HSC overestimated HEC by 20 % (R2 = 0.78). However, during the latter part of the season (straw and bare soil) we found that under highly unstable atmospheric stratification, HSC is even more overestimating HEC and sometimes is even exceeding the available energy. The main reason for such behavior can be the choice of the universal stability function in the computation of HSC. Recommendations for universal functions that are correcting this artifact in HSC will be discussed.Acknowledgment: This study was supported by SustES - Adaptation strategies for sustainable ecosystem services and food security under adverse environmental conditions (CZ.02.1.01/0.0/0.0/16_019/0000797).
Modeling ICME flux ropes as bent and distorted tubes
Authors: Weiss Andreas Jeffrey , Nieves-Chinchilla Teresa , Reiss Martin , Moestl Christian
Published: February 2023

We present the latest results in our ongoing work to construct a generalized analytical flux rope model. Our previously published writhed flux rope model is extended to include non-circular cross-sections to better mimic the magnetic field measurements that are seen in situ and imaging observations. We implement our new model within the scope of a fast forward simulation model that propagates a flux rope away from the Sun into the heliosphere and can generate synthetic magnetic field measurements at arbitrary positions. This flux rope is continuously deformed along its axis due to interaction with the ambient solar wind which is provided by other models. We use our model and the forward simulation in an attempt to reconstruct the global picture of a particular multi-point ICME event.
Research on motion characteristics of floating breakwater with pneumatic chamber
Authors: Lin Ta Wei , Weng Wen Kai , Wang Bo Jun
Published: February 2023

The main purpose of this research is to use the boundary element method to establish a three-dimensional numerical model to simulate the stability and wave resistance of the structure based on the application of floating breakwater with pneumatic chamber.From the two-dimensional numerical model and experimental results, it is found that the pneumatic chamber under a floating body can make the floating body give a resistance force when waves are affected, and increase the ability of the floating body to resist waves.This research focuses on the difference in stability and anti-wave effects under this influence. Numerical simulation is based on small amplitude wave theory, constructing numerical model with three-dimensional boundary element method, discussing the Response Amplitude Operators (RAO) of the structure under the action of waves.
Mobile Eddy-covariance tower network in the Dutch peatlands – Data-driven gap-filling creating site-specific Ecosystem Response Functions.
Authors: Bataille Laurent , Berghuis Hanne , Biermann Jan , Jans Wilma , Buzacott Alexander , Franssen Wietse , van der Poel Laura , Nouta Reinder , Kruijt Bart , Hutjes Ronald
Published: February 2023

In the Netherlands, the peat soils degradation is estimated to contribute annually from  4.6 to 7 Mt CO2, representing around 3% of the annual national GHG emissions. Following the Paris Agreement, the Dutch government presented a national Climate agreement in 2019; reducing net CO2 emission of fen meadows by 1 Mt CO2 per year is part of the objectives for 2030. In order to comply with this, the Ministry of Agriculture, Nature and Food Quality set up a research consortium, The Dutch National Research Programme on Greenhouse Gases in Peatlands. The NOBV implemented an intensive GHG monitoring network mainly based on gas chambers, on-site and airborne Eddy-Covariance measurements. Mapping these emissions according to the diversity of peat, edaphic conditions, grassland management, and water table management is one of the challenges of this research programme.25 measurement sites are part of the NOBV Eddy-Covariance Network and are currently investigated using Mobile EC towers; using mobile EC towers instead of permanent ones is a pragmatic solution to embrace this site diversity. These mobile station set-ups include meteorological variables measurement, these alternate between closely located sites with different characteristics, assuming the meteorological variation is weak between both. Constructing annual GHG budgets requires a robust gap-filling method, able to operate for large gaps; the traditional gap-filling algorithms require long-term measurements, while this project occurs during a limited time window. These algorithms also usually fail at predicting fluxes after abrupt changes. By combining external data sources, remote-sensing and data mining, the objective is to decrease the uncertainties introduced by these gaps in a consistent way.More than time-series gap-filling, this approach provides site-specific data-driven Ecosystem Response Functions, it constitutes the first step to a bottom-up approach that will take into account more site-specific parameters. The interpretation of purely data-driven models is not as straightforward as process-based models, requiring the use of more ML-oriented tools, such as Shapley values. Another challenge is the partitioning of fluxes between the peat degradation-related emissions and the plant photosynthetic curves based on these data-driven models, highlighting the effect of external drivers such as soil moisture/temperature and water table depth.
Investigating relationships between surface rupture and multiple source parameters of earthquakes
Authors: Yao Suli , Yang Hongfeng , Tang Ziyue
Published: February 2023

Surface rupture produced by earthquakes can pose great threat on near-surface infrastructures and elevate damages. Accessing the potential of surface rupture along faults is critical to mitigating such hazards. It is commonly suggested that earthquakes with Mw>6.5 will break the surface. However, there are events with much smaller magnitudes rupturing the ground. To understand the potential controlling mechanisms, we first collect source parameters for earthquakes with  and  surface-breaching events in seismically active regions including west China, North America, Europe, Taiwan, Japan, and Iran. For strike-slip and normal events, almost all earthquakes with magnitudes over 6.7 broke the surface. In contrast, buried and surface-breaching events co-exist with moderate magnitude (6.0-6.7). For reverse events, there is no clear magnitude boundary, as thrust buried events can be quite large due to the downdip size of the seismogenic zone. The relocated hypocenter depths for moderate-to-large events are concentrated at depth of 5 -20 km with no systematic difference between buried and surface-breaching ruptures. Differently, all  surface-breaching events occurred at very shallow depths (<5 km). We also conduct dynamic rupture simulations and propose two conceptual models to explain whether or not ruptures may break the surface. The first model represents a fault with a continuous but heterogeneous seismogenic zone (velocity-weakening) that can hold moderate-to-large earthquakes. In this case, ruptures need to overcome the shallow velocity-strengthening zone (VS) with certain energy sink to reach the surface. Therefore, a thinner shallow RS zone and a higher stress drop of the earthquake can promote surface rupture, consistent with our observations. However, ruptures nucleating from different locations on heterogeneous faults may lead to different surface rupture patterns and final magnitudes, shedding lights on the diverse behaviors among moderate earthquakes. The second model is for small surface-breaching earthquakes. Those events are supposed to occur on shallow isolated velocity-weakening patches, consistent with the fact that usually no large earthquakes have been reported on the same fault zones. Such asperities may be formed on bodies with high-strength materials, leading to energetic ruptures with intense stress release. Our study contributes to the understanding of the surface rupture behaviors references for assessing near-surface damage in future earthquakes. 
Detection, attribution and specifying mechanisms of hydrological changes in geographically different river basins
Authors: Gelfan Alexander , Kalugin Andrey , Krylenko Inna
Published: February 2023

Our study is aimed at detection of directional trends in streamflow data observed in four large rivers (Lena, Selenga, Vyatka, and Pechora) located in different climatic zones and attribution of the detected changes to climate drivers. We consider detection and attribution as interrelated study stages within a suggested hypothesis testing framework with the use of a hydrological model developed on the basis of the ECOMAG modelling platform.

First, we test the significance of the trends in the observed streamflow data series of 74 to 82 years long and evaluate the model’s ability to reproduce the trends, so that the trends in the simulated data are statistically indistinguishable from the corresponding observed trends. Herewith, the model is forced by the reanalysis climate data. Then, for the basins where the model reproduces the trends, we move to the attribution stage of the study. At this stage, the hydrological model is forced by the counterfactual (detrended) climate data prepared within the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP3a) (Mengel et al., 2021). If the trend is not detected in the counterfactual-climate-forced simulations, we conclude that the detected observed changes are likely to be attributed to the climate trend.

We found that the trends fitted to the observed annual flow series are statistically significant for all the four basins, and the trends fitted to the corresponding simulated series are significant too. Herewith, the differences between the detected trends in the observation and simulation data are insignificant for three basins out of four (except the Pechora). For high flow indicators, the trend detection conditions were met for two basins – the Lena and the Selenga, while for the Vyatka and Pechora the model overestimated the changes. Use of the counterfactual data as the input into the hydrological model resulted in removing trends from simulated annual and high flow series, which allowed us to conclude that the directed changes statistically detected in the observed flow series, are most likely to be attributed to climate change for the periods of observations. In terms of annual flow, we consider this proven for the Lena, Selenga and Vyatka rivers; in terms of high flow - for the Lena and Selenga rivers.  Regional differences in basin mechanisms governing the detected changes are analyzed.
Evolving relationship of Nares Strait ice arches and the North Water, the Arctic’s most productive polynya
Authors: Moore Kent , Howell Steve , Brady Mike
Published: February 2023

Nares Strait, the waterway that separates northwest Greenland from Ellesmere Island, is a major pathway along which sea ice leaves the Arctic, including the planet’s oldest and thickest sea ice that is experiencing an accelerated loss.     Ice arches that develop during the winter at the Strait’s northern or southern terminus can remain stable for extended periods during which the transport ceases. The Arctic’s most productive polynya, the North Water (NOW) or Pikialasorsuaq (West Greenlandic for ‘great upwelling’) forms at the Strait’s southern end in part due to the presence of a nearby southern arch.  There is evidence that a warming climate and the concomitant thinning of Arctic sea ice is weakening the arches and it has been proposed that this may lead to detrimental changes to the NOW. Here we use examples from recent years to explore the impact that the absence of a southern arch has on the NOW.  We find that winters with no southern ice arch are associated with a northward expansion of the NOW characterized by reduced  and thinner ice cover as well as enhanced  primary productivity.   In these years, there is an acceleration of the winds along the Strait that assists in the expansion.

 
Assessing the ability of a seamless short-range ensemble rainfall product to detect flash floods on the French Mediterranean area
Authors: Godet Juliette , Bouttier François , Javelle Pierre , Payrastre Olivier
Published: February 2023

Flash floods have dramatic economic, natural and social consequences, and efficient adaptation policies are required to reduce these impacts, especially in a context of global warming. This is why it remains essential to develop more efficient flash flood forecasting systems. This study was carried out in order to assess the ability of a new seamless short range ensemble rainfall forecast product, called PIAF-EPS and recently developed by Meteo France, to predict flash floods when it is used as input in an operational hydrological forecasting chain.For this purpose, eight flash flood events that occurred in the French Mediterranean region between 2019 and 2021 were reproduced, using a similar forecasting chain as the one implemented in the French “Vigicrues-Flash” operational flash flood monitoring system. The hydrological forecasts obtained from PIAF-EPS were compared to the hydrological simulations obtained from the radar observations, and to three deterministic forecasts using varied scenarios (future constant rain, deterministic PIAF, and a numerical nowcasting system called AROME-NWC).The verification method applied in this work uses rank diagrams and scores calculated on contingency tables, in an original way. The verification process has been conducted on each 1km² pixel of the territory.The results illustrate the added value of the ensemble approach for flash flood forecasting, and the benefits of the use of a “seamless” product combining radar observations and numerical nowcasting.   
Effects of Ocean Alkalinity Enhancement in deep and bottom water formation regions on the 21st century CO2 uptake under low and high emission pathways.
Authors: Nagwekar Tanvi , Nissen Cara , Hauck Judith
Published: February 2023

Subduction regions play an important role in transferring carbon from the surface to the deep ocean and sequestering it on a multi-decadal to centennial timescale. Hence, we test the hypothesis that a Carbon Dioxide Removal (CDR) method, namely Ocean Alkalinity Enhancement (OAE) based on olivine addition, is more efficient in deep and bottom water formation region in terms of enhancing the ocean CO2 uptake.Using an ocean-only setup of the physical-biogeochemical model FESOM2.1-REcoM3, we quantify the responses to the spatially uniform and continuous addition of olivine (alkalinity, silicic acid and iron) over the period of 2030-2100 under the SSP1-2.6 and SSP3-7.0 emission scenarios in a global (3 Pg olivine/yr) and a regional application (0.22 Pg olivine/yr). For the regional case, we deposit olivine in the major deep and bottom water formation areas of the Southern Ocean, in the Labrador Sea and the Norwegian Sea.Under the SSP1-2.6 (SSP3-7.0) scenarios, CO2 uptake increases by 1.2 (1.3) Pg C/yr by the end of the 21st century in the global case, whereas it increases by 0.2 (0.2) Pg C/yr in the regional case. The area of uniform olivine deposition is significantly smaller in the regional case compared to the global case, yet the regional OAE has a 2.3-fold higher CDR potential compared to the global OAE in both emission scenarios. The high CDR potential in the regional case is largely (80%) attributed to enhanced biological activity resulting from nutrient fertilization in the Southern Ocean, while only 20% is due to enhanced alkalinity. However, the nutrient effect decreases over time. Furthermore, nutrient addition promotes small-phytoplankton calcification in global and regional OAE cases, leading to lower surface alkalinity by the end of the century. Interestingly, CDR potential of adding alkalinity only (without nutrients) is also 4% and 6.6% higher in the subduction regions than in global OAE under the SSP1-2.6 and SSP3-7.0 scenarios. Overall, the subduction regions, hence show higher CDR efficiency in both cases (alkalinity+nutrients, only alkalinity addition). This effect is two orders of magnitude larger when nutrients are included as this essentially includes Southern Ocean iron fertilization.