Mesoscale Factors Research Articles

Influence of the CO2–brine–rock interaction on the plastic zone of sandstone

During the long-term CO2 storage process, the CO2–brine–rock interaction (CBRI) may change the elastic-plastic behaviors of sandstone reservoirs, potentially leading to rock damage and CO2 leakage. A good understanding of the influence of the CBRI on the plastic zone of sandstone is crucial for evaluating the rock fracturing processes. In this paper, three-point bending tests were conducted under both monotonic and cyclic loading conditions, and the digital image correlation technique was used to analyze the elastic and plastic characteristics of the samples. The experimental results showed that the CBRI decreases the yield strength and corresponding crack mouth opening displacement by 25 % and 65%, respectively, thus increasing the probability of fracturing. Additionally, it was found that the CBRI enlarges the plastic zone by about 20 %. The size of the theoretical plastic zone in the sandstone sample for different loads was determined, and the ratio of the plastic zone size in the samples with CO2–brine saturation to that without CO2–brine saturation was found to be about 1.18. Finally, the mesoscale factors affecting the plastic zone size after CO2–brine saturation were analyzed. This study helps to understand the effect of the elastic-plastic behavior of sandstone on reservoir stability during long-term CO2 storage.

Exploring the functional connectivity between the Kis-Balaton Water Protection System and Lake Balaton using satellite data

Lake Balaton, a shallow polymictic freshwater lake in Central Europe, became eutrophic in the 1970s. To retain the inorganic nutrients from the main tributary River Zala, a semi-artificial system called the Kis-Balaton Water Protection System (KBWPS) was constructed in the early 1980s. In 2015, the system was reconstructed and modernised, thus offering the opportunity to evaluate the effectiveness of the functional connection between the KBWPS and Lake Balaton over the past 20 years and to compare its impact before and after the reconstruction. To this end, time series data of algal biomass in Lake Balaton between 1999 and 2019 based on Landsat 7 satellite data were analysed. Over the last 20 years, the algal biomass in Lake Balaton showed an increasing trend (0.009 ± 0.011% increase per year), with territorial specificities also observed. No change was noted in the western part, while an increase was recorded in the eastern part of the lake. A significant difference in the rate of algal biomass accumulation was noticed before (annual increase of 0.008 ± 0.019%) and after (0.240 ± 0.306% per year) the KBWPS reconstruction. Given that the largest increase in algal biomass after reconstruction was observed in the outermost KBWPS basin of Lake Balaton, it appears that mesoscale environmental, water balance, or other factors affecting the lake are playing a role in this increase, rather than the KBWPS reconstruction. This research highlights the potential to study aquatic ecosystems using Earth observation techniques, and how mesoscale factors such as changes in the local climate regime or shifts in lake management can greatly impact the trophic state of a large shallow lake. Effectively identifying these factors is crucial in maintaining the proper status of aquatic ecosystems.

Mesoscale Factors Contributing to the Extreme Rainstorm on 20 July 2021 in Zhengzhou, China, as Revealed by Rapid Update 4DVar Analysis

Abstract The purpose of this study is to diagnose mesoscale factors responsible for the formation and development of an extreme rainstorm that occurred on 20 July 2021 in Zhengzhou, China. The rainstorm produced 201.9 mm of rainfall in 1 h, breaking the record of mainland China for 1-h rainfall accumulation in the past 73 years. Using 2-km continuously cycled analyses with 6-min updates that were produced by assimilating observations from radar and dense surface networks with a four-dimensional variational (4DVar) data assimilation system, we illustrate that the modification of environmental easterlies by three mesoscale disturbances played a critical role in the development of the rainstorm. Among the three systems, a mesobeta-scale low pressure system (mesolow) that developed from an inverted trough southwest of Zhengzhou was key to the formation and intensification of the rainstorm. We show that the rainstorm formed via sequential merging of three convective cells, which initiated along the convergence bands in the mesolow. Further, we present evidence to suggest that the mesolow and two terrain-influenced flows near the Taihang Mountains north of Zhengzhou, including a barrier jet and a downslope flow, contributed to the local intensification of the rainstorm and the intense 1-h rainfall. The three mesoscale features coexisted near Zhengzhou in the several hours before the extreme 1-h rainfall and enhanced local wind convergence and moisture transport synergistically. Our analysis also indicated that the strong midlevel south/southwesterly winds from the mesolow along with the gravity-current-modified low-level northeasterly barrier jet enhanced the vertical wind shear, which provided favorable local environment supporting the severe rainstorm.

Environmental Evolution of Supercell Thunderstorms Interacting with the Appalachian Mountains

Abstract The Appalachian Mountains have a considerable impact on daily weather, including severe convection, across the eastern United States. However, the impact of the Appalachians on supercells is not well understood, posing a short-term forecast challenge across the region. While case studies have been conducted, there has been no large multicase analysis of supercells interacting with complex terrain. To address this gap, we examined 62 isolated warm-season supercells that occurred within the central or southern Appalachians. Each supercell was broadly classified as “crossing” or “noncrossing” based on their maintenance of supercellular structure during interaction with significant terrain features. Rapid Update Cycle (RUC) and the Rapid Refresh (RAP) model analyses were used to identify key synoptic and mesoscale factors that distinguish between environments supportive of crossing versus noncrossing supercells. Roughly 40% of supercells were sustained crossing significant terrain. Pre-storm synoptic features common among crossing storms (relative to noncrossing storms) included a stronger polar jet, a deeper trough, a north–south-oriented cold front, a strong prefrontal low-level jet, and no wedge front leeward of the terrain. Mesoscale environmental differences were determined using near-storm model soundings collected for each supercell at three locations: upstream initiation, peak terrain, and downstream dissipation. The most significant mesoscale differences were present in the peak and downstream environments, whereby crossing storms encountered stronger low-level vertical shear, greater storm-relative helicity, and greater midlevel moisture than noncrossing storms. Such results reenforce the notion that sustained dynamical support for mesocyclones is critical to supercell maintenance when interacting with significant terrain. Significance Statement The ability of isolated storms with rotating updrafts to traverse complex terrain is not well understood and is a notable forecast problem in the eastern United States due to the Appalachian Mountains. This study represents the first systematic analysis of numerous warm-season supercells in the vicinity of the central and southern Appalachians. We focus on synoptic and near-storm mesoscale environmental differences between storms that maintain supercellular structure following terrain interaction (“crossing”) and those that do not (“noncrossing”). The results provide useful environmental metrics for forecasting supercell longevity in the vicinity of the Appalachian Mountains.

A mesoscale bubble-induced turbulence model and simulation of gas–liquid flows

In gas–liquid two-phase flows, bubble motion significantly affects liquid phase turbulence, and adding bubble-induced turbulence (BIT) source term is widely used to improve the simulation accuracy. This paper presents a new BIT model based on the energy-minimization multi-scale (EMMS) methodology. The model was constructed by considering two mesoscale factors, i.e., the sub-grid structures through analyzing the slip velocity and the gas holdup gradient, and the equivalent diameter of turbulent eddies calculated by the EMMS-based turbulence model. In order to verify its performance, the model was incorporated to the Eulerian–Lagrangian simulating framework and applied to two typical experimental systems. Both mean flow characteristics and turbulence quantities were well predicted, and the new model showed advantages over traditional BIT models, especially at higher gas velocities. Moreover, a strategy for counting energy dissipation in the simulation was devised and performed whereby the dual effects of promotion and suppression on liquid phase turbulence by bubbles can be reflected. The simulations demonstrated that BIT dominated the energy dissipation and turbulence was enhanced by BIT at higher gas velocities, while shear-induced turbulence dominated the energy dissipation and turbulence is reduced due to the suppression by bubbles at lower gas velocities.

A Climatology of Snow Squalls in Southern New England 1994–2018

Abstract Snow squalls are sudden snow events that last less than 1 h, are characterized by low visibility and gusty winds, and can result in notable societal impacts. This analysis develops a climatology of non-lake-effect snow squall events in southern New England for 1994–2018 and investigates the synoptic environment and mesoscale factors conducive to their formation. National Weather Service surface observations were used to identify events; sea level pressure maps, composite radar charts, and a cell-tracking algorithm were used to determine their organization and movement; and ERA5 hourly reanalysis data were used to analyze the associated synoptic and infer mesoscale features, as well as convective and symmetric instability. A total of 100 events were identified and categorized into four distinct types on the basis of the direction of movement of the associated radar echoes, which is closely linked to characteristic synoptic structures and mesoscale factors. The four types are Classic (squall movement from the northwest; 72 events), Atlantic (from the southwest; 15 events), Northern (from the north; 9 events), and Special (varying; 4 events). All types have a 500-hPa trough over the Northeast but differ in the structure of the trough and its relation to lower-level flow, which accounts for the differences in movement of the squalls. The snow events occur in shallow, convective squall lines, and the ingredients for convection were present in all cases. Both upright and symmetric instability are typically present, all cases had at least one lower-tropospheric layer with cyclonic differential vorticity advection, and many cases were also associated with frontogenesis.

Does neighborhood design matter for walk access to metro stations? An integrated SEM-Hybrid discrete mode choice approach

This study explores effects of various subjective and objective built environment (BE) factors on access mode choice to Metro stations. Personal interview surveys were conducted among 600 Metro users from catchment area of Metro stations in Delhi, India to collect information regarding their socio-economic status, access travel characteristics, and degree of satisfaction on twenty microscale BE factors related to walking environment. Secondary data on mesoscale factors such as population- and employment-density and land-use diversity were also collected. Exploratory factor analysis on microscale factors yielded a four-factor solution, i.e., Comfort, Safety & Security, Traffic, and Mobility which is confirmed by confirmatory factor analysis. These four factors were utilized to derive an endogenous variable “Neighborhood Design”. Four access mode choice models were developed subsequently using hybrid discrete choice models taking Neighborhood Design as walkability measure. The results indicated that Neighborhood Design, population, and land-use densities affect mode choice positively and significantly. The research indicates that improving microscale Neighborhood Design and certain mesoscale factors within catchment areas of stations could influence the peoples’ choice of walking to the stations. Sensitivity analysis also shows that improvement in the neighborhood design attributes will lead to a higher share of walk access to metro stations.

Fire-spotting generated fires. Part II: The role of flame geometry and slope

This is the second part of a series of two papers concerning fire-spotting generated fires. While, in the first part, we focus on the impact of macro-scale factors on the growth of the burning area by considering the atmospheric stability conditions, in the present study we focus on the impact of meso-scale factors by considering the effects of the flame geometry and terrain slope. First, we discuss the phenomenological power law that relates flame length and fireline intensity by reporting literature data, analysing a formula originally proposed by Albini, and deriving an alternative formula based on the energy conservation principle. Subsequently, we extend the physical fire-spotting parametrisation RandomFrontadopted in the first part by including flame geometry and slope. Numerical examples show that fire-spotting is affected by flame geometry and, therefore, cannot be neglected in simplified fire-spread models used in operational software codes for wildfire propagation. Meanwhile, we observe that terrain slope enhances the spread of a fire at a higher rate than the augmentation of fire-spotting generated fires, such that a rapid merging occurs among independent fires.

The Sequence of Heavy Precipitation and Flash Flooding of 12 and 13 September 2019 in Eastern Spain. Part I: Mesoscale Diagnostic and Sensitivity Analysis of Precipitation

AbstractThe Mediterranean region is frequently affected by heavy precipitation episodes and subsequent flash flooding. An exemplary case is the heavy precipitation episode that occurred in the regions of València, Murcia, and Almería (eastern Spain) on 12 and 13 September 2019. Observed rainfall amounts were close to 500 mm in 48 h, causing seven fatalities and estimated economical losses above EUR 425 million. This case exemplifies the challenging aspects of convective-scale forecasting in the Mediterranean region, with kilometer-resolution meteorological fields required over long forecast spans. Understanding the key mesoscale factors acting on the triggering, location, and intensity of the convective systems responsible for extreme accumulations is essential to gain insight into these episodes and contribute toward their accurate hydrometeorological forecasting. Mesoscale diagnosis suggests that local and distant orography, together with air–sea fluxes, were instrumental in developing convection and intensifying precipitation rate. Sensitivity experiments confirm the role of orography in organizing the cyclonic flow over the southeast part of the western Mediterranean, and also acting as a convection-triggering mechanism. Furthermore, results highlight the role of latent heat flux from the Mediterranean Sea in enhancing convective instability at lower levels and moistening the environment. These moist feeding flows substantially contribute to increasing precipitation rates. Such high sensitivity to environmental moisture distribution naturally propagates to the sea surface temperature, which, by means of sensible and latent heat flux exchanges, dominated the evolution of convective activity for the 12–13 September 2019 episode.

Are land rental markets responding to rising population pressures and land scarcity in sub-Saharan Africa?

Although still at incipient stages in most areas, agricultural land markets in sub-Saharan Africa (SSA) are growing rapidly. While the literature on the region’s land markets is expanding, there has been little attention thus far paid to the drivers of land rental prices. We know quite little about whether and how land markets and land contracts respond to meso-scale factors such as spatial variations in land abundance, or to micro-level factors, such as household land endowments. In this paper, we study the response of land markets, and hence whether land market participation trends and land market rental prices respond to land scarcity. Drawing on nationally representative household survey data from Ethiopia, Malawi and Tanzania, which represent a large range of relative land scarcity conditions, we examine how land markets are responding to cross-sectional variations in land scarcity in terms of rental market participation rates, prices, and contractual arrangements. In all three countries, we document that rental market participation rates and land rental prices increase with land scarcity. We also find that land rental prices per hectare decrease with plot size. These land market responses and their heterogeneities have important implications for land distribution and land market policies.

Fire-spotting generated fires. Part I: The role of atmospheric stability

This is the first part of two papers concerning fire-spotting generated fires. In this part we deal with the impact of macroscale factors, such as the atmospheric stability, and in the second part we deal with mesoscale factors, such as the flame geometry. For this study we adopt an approach where the motion of the front is split into a drifting part and a fluctuating part. The drifting part, that can be provided by choosing an existing operational model, is here based on the level-set method in analogy with WRF-SFIRE model. The fluctuating part, that is the result of a comprehensive statistical description of the physics of the system and includes the random effects, is here physically parametrized to include turbulent hot-air transport and firebrand landing distance. In order to highlight the net effects of the random contributions due to turbulence and firebrand flying, a simplified model without fire-atmosphere coupling is considered. Numerical simulations show that the atmospheric stability is an important factor for wildfire propagation. In particular, unstable conditions boost the number of fire-spotting generated fires at small elapsed times as well as the strength of turbulence leading to rapid merging and the formation of unburned islands surrounded by the fire. Stability conditions have then an effect on the risk and the management associated to fire-spotting generated fires. In fact, with stable conditions (corresponding for example to the night-time) the turbulence is not strong enough to merge the fires and, at large elapsed times, this results into a higher number of independent fires but lower burned area with respect to unstable conditions (corresponding for example to the day-time) when the push of turbulence leads to faster merging resulting into a lower number of independent fires but higher burned area. Finally, with stable conditions less fire fronts need to be managed at short time, but more fire fronts need to be managed than with unstable conditions that however show a higher risk because of the merging of independent fires.

Multiscale finite element based trans-scale calculation method for polycrystalline materials

In the present paper a multiscale finite element based trans-scale calculation method for polycrystalline materials is proposed to investigate the interaction between mechanical properties at macro and meso scale. The model analyzes the interaction between macro-scale factors such as structure and loads, and meso-scale factors such as geometry, distribution and orientation of polycrystal. Multiscale finite element was created by user subroutines of the ABAQUS. Also Voronoi diagram based polycrystalline finite element was realized by MATLAB. The polycrystalline finite element and the conventional finite element were connected using the multiscale finite element. The mesh independency and convergence of the model were investigated with perforated plate, and the correctness and feasibility of the model were verified with a laser repaired compact tensile specimen. The number of degrees of freedom of multiscale finite element based trans-scale calculation model for polycrystalline materials is much smaller than that of the model with the fine-scale elements, but the reduction in calculation accuracy is negligible. The model can be used to study the mechanical behavior of heterogenous materials simultaneously by combining meso-scale and macro-scale with a smaller amount of computation.

Assessment of Climate Change Impacts on the Economic Development of the Russian Arctic in the 21st Century

The problem of increasing the informativeness of climate projections in the Russian Arctic in order to meet the current economy needs is considered. The detailed estimates are presented of changes for the most important specialized indicators of the thermal and moisture regimes which characterize climatic impacts on the economic development of the Russian Arctic in the 21st century. The calculations are based on the data of numerical experiments with the regional climate model which were conducted for the Arctic region in the framework of the international CORDEX project. The high resolution of the model (50 km) and the consideration of mesoscale factors helped to detect significant spatial differences in the estimates of changes in the analyzed parameters which should be taken into account when adapting to climate change at the regional level.

Important Factors for Tornadogenesis as Revealed by High-Resolution Ensemble Forecasts of the Tsukuba Supercell Tornado of 6 May 2012 in Japan

To identify important factors for supercell tornadogenesis, 33-member ensemble forecasts of the supercell tornado that struck the city of Tsukuba, Japan, on 6 May 2012 were conducted using a mesoscale numerical model with a 50-m horizontal grid. Based on the ensemble forecasts, the sources of the rotation of simulated tornadoes and the relationship between tornadogenesis and mesoscale environmental processes near the tornado were analyzed. Circulation analyses of near-surface, tornadolike vortices simulated in several ensemble members showed that the rotation of the tornadoes could be frictionally generated near the surface. However, the mechanisms responsible for generating circulation were only weakly related to the strength of the tornadoes. To identify the mesoscale processes required for tornadogenesis, mesoscale atmospheric conditions and their correlations with the strength of tornadoes were examined. The results showed that two near-tornado mesoscale factors were important for tornadogenesis: strong low-level mesocyclones (LMCs) at about 1 km above ground level and humid air near the surface. Strong LMCs and large water vapor near the surface strengthened the nonlinear dynamic vertical perturbation pressure gradient force and buoyancy, respectively. These upward forces made contributions essential for tornadogenesis via tilting and stretching of vorticity near the surface.

Smart aggregates for monitoring stress in structural lightweight concrete

Stress monitoring using piezo-electric smart aggregate (SA) provides a useful way to assess damage in concrete structures. Although the feasibility has been verified in normal weight concrete (NWC), efforts are needed for lightweight concrete (LWC) due to the differences in meso-scale factors that is key for SA-based monitoring. In this paper, SA sensors were tested for monitoring stress using four identical LWC cylinders with six SAs embedded in each specimen subjected to typical loading paths and load levels. Based on the test results, the effects of the related meso-scale factors on the feasibility of monitoring were evaluated. After that, the sensors’ sensitivity curve and the extent of SA output randomness were quantified. It can be concluded that SAs have potential for monitoring stress in LWC structures during the entire damage process.

Circulation weather types associated with extreme flood events in Northwestern Mediterranean

ABSTRACTThe aim of this work was to identify the circulation weather types associated with flood events that occurred in Catalonia (Northeastern Spain) during the period 1900–2010. To achieve this objective, 261 extraordinary and catastrophic flood and flash flood events that were recorded during this period were characterized and classified based on impact data. A preliminary analysis of maximum precipitation and discharge was conducted in order to have some quantitative hydrometeorological indicators associated with these kinds of events. The objective classification developed by Jenkinson and Collison, which is based on differences in synoptic patterns according to surface pressure, was implemented. Once the weather regimes for each flood event had been established, a statistical and comparative analysis was performed that allowed us to determine which synoptic patterns were more frequently associated with the different flood types, their differences and their similarities. The results show that most synoptic situations were pure cyclonic structures, in both extraordinary and catastrophic events, although they were more frequent in the latter. Catastrophic floods generally had a synoptic origin enhanced by certain mesoscale factors, while extraordinary floods were usually associated with local flash floods that occurred primarily in summer and early autumn, highlighting the undetermined types that were not reflected at a synoptic scale. As the Mediterranean basin is a region where floods cause serious socio‐economic impacts, this work will help improve prevention measures and provide information for policymakers, mainly for land‐use planning and early warning systems.

Influence of Nitrogen Vacancy Concentration on Mechanical and Electrical Properties of Rocksalt Zirconium Nitride Films

To study the influence of the nitrogen vacancy (V N) on mechanical and electrical properties of zirconium nitride deeply, ZrN x films with different V N concentrations were synthesized on the Si (111) substrates by enhanced magnetic filtering arc ion plating. The morphologies, microstructures, residual stresses, compositions, chemical states, mechanical and electrical properties of the as-deposited films were characterized by field-emission scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectrometry, Nanoindenter and Hall effect measurements. The results showed that ZrN x films exhibited rocksalt single-phase structure within a V N concentration ranging from 26 to 5%. The preferred orientation, thickness, grain size and residual stress of the ZrN x films kept constant at different V N concentrations. Both the nanohardness and elastic modulus first increased and then decreased with the decrease in V N concentration, reaching the peaks around 16%. And the electric conductivity of the ZrN x films showed a similar tendency with nanohardness. The underlying atomic-scale mechanisms of V N concentration-dependent hardness and electric conductivity enhancements were discussed and attributed to the different electronic band structures, rather than conventional meso-scale factors, such as preferred orientation, grain size and residual stress.

Quantitative distribution of the meiobenthos in Baidaratskaya Bay (Kara Sea)

The quantitative characteristics and spatial distribution of the meiobenthos in Baidaratskaya Bay (Kara sea) were analyzed based on data collected in 1994–2007. The extremely high density of the meiobenthos (up to 8121 ind/10 cm2, average 2318 ind/10 cm2) makes it possible to consider Baidaratskaya Bay among the most productive Arctic regions. The spatial distribution of the meiobenthos was mostly determined by the depth and sediment properties in the subtidal zone of the bay. The density of meiobenthic organisms decreased with depth, and with the increase of the small sediment fraction. The difference in the meiobenthic densities between the two coastal areas of the bay (Yamal and Jugora CAs) is also revealed. Such difference caused by the combined effects of small-scale and mesoscale factors, mainly by the grain size. Opposite changes in the meio- and macrobenthic biomass with depth is shown.

Experimental study on atomic-scale strengthening mechanism of the ⅣB transition-metal nitrides

For deeply understanding on the atomic-scale strengthening mechanism of the ⅣB transition-metal nitrides, three groups of the ⅣB transition-metal nitrides TMN (TiN, ZrN, and HfN) films with different nitrogen contents were synthesized on the Si (100) substrates by enhanced magnetic filtering arc ion plating. The morphologies, microstructures, compositions, chemical states, residual stress, hardness and elastic modulus of as-deposited films were characterized by field emission scanning electron microscope, X-ray diffraction, X-ray photoelectron spectrometry, and Nanoindenter measurements. The results showed that TMNx films exhibited B1NaCl single-phase structure within the large composition ranges. The preferred orientation, thickness, grain size and residual stress of the TMNx films were kept constant at different nitrogen contents. Both nanohardness and elastic modulus first increased and then decreased with the increase of nitrogen content, reaching the peak at x around 0.82. The composition dependent hardness enhancement may be attributed to different atomic-scale chemical bonding states and electronic structures in this work, rather than conventional meso-scale factors, such as preferred orientation, grain size and residual stress.

A new assessment model to evaluate the microscale sidewalk design factors at the neighbourhood level

To date, several assessment tools have been developed to evaluate the pedestrian environments and sidewalks at the street and neighbourhood level. While the existing tools that assess sidewalks at the street level consider the microscale sidewalk factors, the assessment tools at the neighbourhood level neglected the importance of microlevel factors for the assessment purpose. In addition, the important role of residents in neighbourhoods in the examination and review procedure of neighbourhood facilities is overlooked. In contrast with previous assessment methods that considered macro and mesoscale factors for assessment purpose, this research has developed an assessment method to evaluate the neighbourhood sidewalks using the microscale factors. This tool has been developed in the form of a questionnaire to assess the sidewalk conditions within the neighbourhoods. The proposed tool has been tested in three neighbourhoods within Johor Bahru District in Malaysia. Most sidewalk factors in these surveys showed moderate to high reliability. The results of using the proposed tool indicate that the tool is capable of identifying the drawbacks of neighbourhood sidewalks. In addition, this tool allows the residents to convey their needs to city planners and ask for improving existing sidewalks. Lastly, the tool appears ready to be used by urban planners and researchers.