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We have developed the SNOVAL computational code to numerically simulate snow accretion on the conductor wire of a transmission line. Here, we present the theoretical aspects of SNOVAL version 2 such as the derivations of the model equations based on the physical process of snow accretion and conductor wire torsion, and the derivations of the mathematical form of the spatial and temporal discretization of the model equations. The validity of SNOVAL is examined using observational data obtained using a sector model apparatus designed to mimic snow accretion and wire rotation at the center of an actual transmission line. Field observations indicate that the SNOVAL snow accretion model is appropriate, although the SNOVAL results depend strongly on certain computational conditions such as the sticking efficiency, the accreted snow density, and an assumed mass-weighted terminal fall speed of wet snowflakes. Finally, the applicability of SNOVAL to snow accretion on a transmission line is demonstrated via numerical simulation of the dynamic behavior of wire rotation such as the snap-through phenomenon of a conductor wire equipped with counterweights. • SNOVAL was developed to numerically simulate snow accretion on a conductor. • Snow accretion model was validated using field observations of a sector model. • SNOVAL can simulate snap-through rotation of a conductor wire with counterweights. • Counterweights are effective in suppressing snow accretion and wire rotation. [ABSTRACT FROM AUTHOR]

• Operating shield tunnels affected by both the nearby and overlying excavation simultaneously in sensitive soft soils were investigated and presented. • The mechanism of improving the safety and serviceability of existing tunnels through tunnel reinforcement was revealed. • The impact of tunnel reinforcement on the adjacent existing tunnel during the construction stage was discussed. • Empirical methods estimating the impact range of side excavation, overlying excavation, and reinforcement construction were proposed. Adjacent engineering activities affect existing tunnels in service, causing safety concerns. Many studies have focused on single excavations overlying or parallel to adjacent existing tunnels. However, few have considered the responses of tunnels to multiple excavations with different orientations. In this study, the existing shield tunnels of Hangzhou Metro Lines 1, which were affected by both the nearby and overlying excavation simultaneously, in sensitive soft soils were investigated and presented. Field monitoring showed considerable displacement in the tunnels at different excavation stages. The interaction mechanism between the nearby and overlying excavation, the surrounding soil, and the existing tunnels was investigated by assessing the evolutionary pattern of the tunnel deformation. In addition, the mechanism of improving the safety and serviceability of tunnels through tunnel reinforcement, which has been ignored in past research, and the impact of tunnel reinforcement on the tunnel during the construction phase were evaluated. Empirical methods were proposed to estimate the impact range of nearby and overlying excavation and tunnel reinforcement construction. The results provide guidance for protecting metro tunnels during adjacent excavations in soft soils. [ABSTRACT FROM AUTHOR]

The particulate matter (PM) pollution has been significantly improved by carrying out various valid emission control strategies since 2013 in China. Meanwhile the variation trend of nitrous acid (HONO) is worthy to investigate due to its vital role in the atmospheric oxidation process. In this study, field observation in the winter is conducted to investigate the concentration of HONO in an urban area of Beijing. In the winter of 2019, the mean HONO concentration is 1.38 ppbV during the whole winter. Photo-enhanced NO 2 heterogeneous reactions on the ground and aerosol surfaces were found as the possible daytime sources of HONO. Compared to O 3 , photolysis of HONO dominates the primary OH sources during the winter time. To understand the HONO pollution patterns by years variation, multi-year data is summarized and finds that primary pollutants including CO and NO decreased, but secondary pollutants i.e., HONO (mostly generated via secondary process) increased. Our study highlights the requirement to mitigate secondary pollution by control HONO concentration. [Display omitted] [ABSTRACT FROM AUTHOR]

As a representative species of intermediate volatile organic compounds (IVOCs), long-chain alkanes are considered to be important precursors of secondary organic aerosols (SOA) in the atmosphere. This work reviews the previous studies on long-chain alkanes in the atmosphere: (1) the detection methods and filed observations of long-chain alkanes in both gas and particle phases are summarized briefly; (2) the laboratory studies of long chain alkanes are reviewed, the kinetic data, reaction mechanism, SOA yields, and physicochemical properties of SOA are included in detail; (3) the research progress related to model simulations of long-chain alkanes are also discussed. In addition, based on available research results, several perspective contents are proposed that can be used as a guideline for future research plans. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Abundant stratified iron deposits have been discovered in the Taxkorgan Terrane. • These iron deposits are unique BIFs of Cambrian age ranging from 540 to 508 Ma. • Magmatism and local anoxic basins controlled the formation of these iron deposits. • The Cambrian ocean most likely was more reduced than previously thought. Abundant bedded iron deposits have been discovered recently in the Taxkorgan Terrane, West Kunlun Orogenic Belt, China. Magnetite is the dominant iron mineral, which is interbedded with amphibolite-facies metamorphic silicate minerals, quartz, and calcite. Field observations revealed that the iron orebodies are hosted in the Bulunkuole Complex, which consists mainly of submarine volcanic and sedimentary sequences. The iron orebodies are typically in conformable contact with bimodal volcanic rocks. The nature of iron mineralization in this region is unclear, mainly because it appears to be similar to typical banded iron formations (BIFs), but is of inferred Cambrian age. We undertook detailed field investigations of this area and zircon U–Pb dating of meta-rhyolites from three iron deposits (i.e., the Zankan, Taaxi, and Ziluoyi deposits). Meta-rhyolites from the deposits have ages of 540.2 ± 2.4, 540.2 ± 2.4 to 515.2 ± 2.7, and 526.4 ± 2.5 to 508.8 ± 3.6 Ma, respectively, indicating that the iron orebodies can be subdivided into four groups, based on their formation ages (i.e., 540, 526, 515, and 508 Ma). These ages suggest that the iron orebodies are unique Cambrian BIFs, although the gangue minerals in these orebodies have been mainly converted into amphibolite-facies minerals, owing to the regional high-grade metamorphism. The close relationship between iron orebodies and bimodal volcanic rocks indicates the iron deposits are Algoma-type BIFs. Abundant pyrite in the iron orebodies from the Zankan deposit suggests that the basin in which these rocks precipitated was sulfidic and in a relatively shallow shelf environment. The lack of pyrite in ores from the Taaxi and Ziluoyi deposits indicates they precipitated in ferruginous basins with relatively deep seawater. We propose that intense submarine magmatism and local anoxic basins were the key factors that controlled the formation of these unique Cambrian BIFs in the Taxkorgan Terrane. [ABSTRACT FROM AUTHOR]

This study analyzed the characteristics of infragravity (hereafter IG) waves under a microtidal and swell-dominated wave climate based on the field observations collected in the nearshore waters (water depth: ∼ 13 m) of southern Sri Lanka. The main focus is on the dependence of nearshore IG waves on the incident short wave parameters, with particular attention to the influence of the short wave spectral shape on the IG wave characteristics. The observation results indicate that IG waves are primarily locally excited by incident swell wave energy, and accurate prediction of the IG wave height can be achieved using the parameter H S 2 T m − 1 , 0 , which represents the short wave energy flux. Bound IG wave energy is much smaller than the free IG wave under conventional sea states but becomes significant under high-energy swell sea states. Higher levels of IG wave energy are found to be forced under narrower spectral shapes and smaller directional spreading short wave conditions, and these conditions typically correspond to stronger coupling strengths in the bound IG wave theory. Compared to the single-peaked spectra wave condition, the forced IG wave energy decreases under the double-peaked spectra wave condition. This is likely mainly because the latter tends to have a broader spectrum and a larger directional spreading. On the other hand, under the narrow-banded spectral short wave conditions, IG wave energy is inclined to be distributed over a lower and smaller frequency range. This is noteworthy because lower-frequency IG waves tend to be more difficult to break. In addition, the bound IG wave energy was found to increase at low tide, but for the intermediate water depths in which the observation site is located in this study, the influence of the small tidal range in the study area on the IG wave energy was not significant. [ABSTRACT FROM AUTHOR]

• FBG-based fiber F-P interferometer strainmeter arrays for field observation. • Large-scale, real-time multiplexed strainmeter array features ultrahigh-resolution. • The array in Lijiang has 4.80-pε/√Hz @ 30 Hz resolution with 0.22-m cavity length. • The array in Heqing has 476-fε/√Hz @ 30 Hz resolution with 1.4-m cavity length. • The arrays have successfully recorded daily earth tides and over 100 earthquakes. Mining mass data of the earth's surface deformation is a promising approach for earthquake early-warning, raising an urgent demand for developing large-scale optical fiber strainmeters. This paper presents the implementation and results of large-scale, ultrahigh-resolution, real-time multiplexed fiber Bragg grating-based Fabry-Perot interferometer (FBG-FFPI) strainmeter arrays for field observation. The Pound-Drever-Hall technique locks master and slave single-sideband lasers onto the FBG-FFPI resonance peaks for precise strain measurement. A 10-channel array was successfully utilized for field observation at Lijiang National Seismic Station, which accurately recorded over 100 earthquakes and the earth's daily tide signal. The FBG-FFPIs have a strain resolution of 4.80 pε/√Hz @ 30 Hz with a 0.22-m cavity length. A 4-channel array with a longer cavity length of 1.4 m was also established at Heqing Seismic Station, showing advantageous performances. These results demonstrate the significant potential of FBG-FFPI strainmeter arrays in providing geophysical data for earthquake early-warning and hazard mitigation. [ABSTRACT FROM AUTHOR]

Roadways adjacent to a mining face are crucial for ensuring safe production, transportation, and the security of personnel. Nevertheless, the anchoring mechanisms and the integrity of the surrounding rock structures of these roadways have frequently been underestimated in mining endeavors. This study, using Xin'an Coal Mine in Gansu as an example, conducted an in-situ analysis of four anchoring methods to examine the axial force fluctuation characteristics and mechanisms of cable anchorage during coal mining. It was found that the lagged prestressed full-length anchorage demonstrated the most effective control. Subsequently, the study revealed the periodic subsidence phenomenon of roadway roofs on both sides of the working face, which is closely associated with periodic weighting. Based on monitoring results, the roadway roof was divided into three zones—'Peak Zone,' 'Valley Zone,' and 'Transition Zone'—using the periodic weighting intervals as units. Finally, the study employed a time-space detection method to observe the development pattern of roadway roof cracks and delamination during the coal mining cycle. The validation results indicated a low accuracy rate for this method. Additionally, the study discussed the applicable conditions for lagged prestressed full-length anchorage, measures to address roof subsidence in the 'Peak Zone,' and considerations for improving the time-space detection method. The research findings offer new insights into the impact of neighboring engineering disturbances on underground space engineering. • Field study of axial characteristics of four anchoring forms for cable bolts. • Revealing the phenomena and causes of roof deformation fluctuations in roadways. • Observing rock mass damage patterns using the time-space detection method. [ABSTRACT FROM AUTHOR]

Cast-in-place pile foundations are widely employed to support basic infrastructures on the Qinghai-Tibet Plateau (QTP). However, concrete hydration heat substantially affects the thermal stabilization of pile foundations in permafrost regions. In this paper, the thermal characteristics of a cast-in-place pile foundation in a warm (>−1 °C) permafrost region on the interior QTP were studied via field observations and numerical simulations. The temperature field observations showed that the peak temperature of the pile foundation occurred two days after the concrete was poured, and that positive temperatures of the pile foundation lasted 21 days. The temperatures at different depths of the pile foundation dropped below 0 °C 93 days after the concrete was poured. However, even 224 days after the concrete was poured, the temperatures in the pile foundation were still higher than that of the natural ground. Based on the observational data, three-dimensional numerical models were established to analyze the thermal disturbances and the freezing process. The results showed that the thickness of the thermal disturbance annulus around the pile foundation was 1.6 m, namely, twice the pile diameter. It would take approximately 420 days for the temperatures in the pile foundation to recover to approximately that of the natural ground. When the mean annual ground temperature (MAGT) decreased, the thickness of the thermal disturbance annulus around the pile foundation increased, and the freezeback time of the pile foundation decreased. [ABSTRACT FROM AUTHOR]

Water-soluble inorganic ions (WSI), a major component of PM 2.5 , often increased rapidly during the haze event in Beijing. Sulfate (SO 4 2−), Nitrate (NO 3 −), and Ammonium (NH 4 +) are three main components of WSI. Since year 2015, sulfate concentrations in PM 2.5 has gradually decreased owing to the effective control of SO 2 emissions. However, the contribution of nitrate to PM 2.5 has significantly increased during haze events in Beijing at the same time. In this study, a highly time-resolved online analyzer (Monitor for Aerosols and Gases, MARGA) was employed to measure the WSI in PM 2.5 in Beijing from 5 February to 15 November 2017. Three typical haze events during this sampling period were investigated. During heavy pollution episodes in winter, nitrate concentrations increased from 7.5 μg/m3 to 45.6 μg/m3 (45.0% of WSI), while sulfate increased from 4.2 μg/m3 to 20.1 μg/m3 (19.8% of WSI). This indicated that nitrate is more important than sulfate as a driver for the growth of PM 2.5 during the period of heavy air pollution in winter. Nitrate also dominates the increase of WSI in the pollution episodes in autumn, with an average concentration of 52.5 μg/m3, and contributed up to 67% of WSI. The average concentration ratio of NH 4 + to SO 4 2− was higher in autumn (1.02) than that in summer (0.74) and close to that in winter (1.00). This is mainly because the emission control of coal combustion in Beijing and surrounding areas results in an NH 3 -rich and SO 2 -lean atmosphere, which promoted the formation of ammonium nitrate. Our study indicates that nitrate has become the most important component of WSI in PM 2.5 and is driving the rapid growth of PM 2.5 concentrations during heavy pollution episodes in Beijing. Therefore, more efforts shall be made to reduce the nitrogen oxide and ammonia emissions in Beijing and surrounding areas. Unlabelled Image • Nitrate become the main component of PM 2.5 than sulfate during the haze events in Beijing. • High NOx emission, low temperature and low aerosol acidity are the key factors to promote nitrate formation in Beijing. • Molar ratio of NH 4 + to SO 4 2- increased from 1.5 (before 2013) to 3.33 (2017) due to ammonia-rich atmosphere in Beijing. [ABSTRACT FROM AUTHOR]

• We analyze pedestrian route choice behavior around obstacles in a simple scenario. • We compare a field study and a virtual experiment with identical setups. • We find qualitatively similar results in both settings. • This helps to validate virtual experiments as a useful methodology. Pedestrians often need to decide between different routes they can use to reach their intended destinations, both during emergencies and in their daily lives. This route-choice behavior is important in determining traffic management, evacuation efficiency and building design. Here, we use field observations and a virtual experiment to study the route choice behavior of pedestrians around obstacles delimiting exit routes and examine the influence of three factors, namely the local distance to route starting points and the pedestrian density and walking speeds along routes. Crucially, both field study and virtual experiment consider the same scenario which allows us to directly assess the validity of testing pedestrian behavior in virtual environments. We find that in both data sets the proportion of people who choose a closer exit route increases as the difference in distance between exit route starting points increases. Pedestrians' choices in our data also depend on pedestrian density along routes, with people preferring less used routes. Our results thus confirm previously established route choice mechanisms and we can predict over 74% of choices based on these factors. The qualitative agreement in results between the field study and the virtual experiment suggests that in simple route-choice scenarios, such as the one we investigate here, virtual experiments can be a valid experimental technique for studying pedestrian behavior. We therefore provide much-needed empirical support for the emerging paradigm of experiments in virtual environments. [ABSTRACT FROM AUTHOR]

• Weld-induced rail squats are studied through a five-year continual field monitoring and numerical simulations. • Different stages in the development of squats were observed in the field monitoring. • The development process is presented, from inhomogeneous material in HAZs to two-lung-shaped squats associated with cracks. • The formation mechanism in terms of dynamic contact force and differential plastic deformation is proposed. • Numerical simulations are performed to verify the pre-cracking process. Weld-induced squats are a major damage type in high-speed railways as well as in conventional railways. They incur high maintenance costs and endanger operational safety. This paper first presents and analyzes five-year continual field monitoring observations and measurements of squats at rail welds. A hypothesis of the formation and development process of the squats is proposed, which includes three steps. Steps 1 and 2 are pre-cracking, and Step 3 is post-cracking. To verify the pre-cracking process, a three-dimensional (3D) finite element (FE) model is then built up to simulate the vehicle-track interaction with detailed consideration of the local wheel-rail frictional rolling contact. Not only dynamic contact forces but also plastic deformation and wear are calculated. Starting from a smooth rail surface with varying yield stress derived from field-measured hardness, the numerical analysis confirms the hypothesis that the varying hardness at heat-affected zones (HAZs) leads to initial V-shaped irregularities due to differential plastic deformation. Afterward, the surface irregularities excite the dynamic longitudinal contact force, which in turn produces a W-shaped surface pattern through further differential plastic deformation. The growth of the W-shaped pattern leads to the formation of squats. This work provides insight into the squat formation process at rail welds and suggests that welding quality control in terms of hardness variation in the HAZs could reduce or even avoid squats. Early detection of squats with dynamics-based methods is possible. [ABSTRACT FROM AUTHOR]

Hydrodynamic and hydrographic data collected on the inner shelf of Fire Island, NY, over a region of shoreface-connected ridges (SFCRs), are used to describe wind-driven circulation over uneven topographies along relatively straight coastlines. The data reveal a predominantly alongshore flow, under westward wind forcing, with localized offshore current veering over the SFCR crests and an onshore veering over the adjacent troughs. Alongshore momentum balance analysis of the observations reveals that total acceleration (i.e., local and advective) and bottom stress are balanced by wind stress and pressure gradient. A numerical model is used to verify the experimentally derived results and to analyze the cross-shore momentum balance which is not resolved by the experimental data. Analysis of the numerical and field data reveal that the total alongshore pressure gradient force can be considered as the sum of a local and a regional component. The former is correlated with the alongshore advective acceleration that develops over the crest of the ridges resembling a Bernoulli-like pressure-flow relationship. The regional alongshore pressure gradient is related to wind stress with which it maintains a strong, negative relationship. Over the ridge crests the cross-shore veering of the flow is due to mass conservation, associated with a balance between cross-shore advective acceleration and local cross-shore pressure gradient. Under variable wind conditions the regional pressure gradients are more important, as compared to quasi steady-state conditions which increase the influence of the local scale pressure gradient. A time scale of 6 h is found as the temporal scale required for the local pressure gradients to make a significant contribution to the momentum balance. • The hydrodynamic driving force was best described as a combination of wind stress and pressure gradient force. The response of the flow was best described by bottom stress, local acceleration, and advective acceleration. • Current veering over shoreface-connected ridges is driven primarily by two processes: cross-shore variation of alongshore advective acceleration which correlates with a cross-shore pressure gradient and drives flow (described as a Bernoulli-like process), and, bottom frictional-torque. • Advective acceleration is exhibited through high current velocity over SFCR crest and low current velocity over SFCR trough. This distribution of current velocities causes: current divergence at SFCR crest and a local water level set-down, as well as a current convergence and water level set-up over troughs. The water level can thus be described as creating a local pressure gradient response to the distribution of advective acceleration, a process heron described as a Bernoulli-like process. • The total pressure gradient force can be considered as the sum of a local and a regional pressure gradient force. The former is correlated with the alongshore advective acceleration that develops over the crest of the ridges resembling a Bernoulli-like pressure-flow relationship. • Under variable wind conditions the regional pressure gradients are more important, as compare to quasi steady-state conditions which increase the influence of the local scale pressure gradient. [ABSTRACT FROM AUTHOR]

Highlights • An equation for estimating the daily UHII max is evaluated with a dataset of 658 days. • Robust and satisfactory estimation of the UHII max under various weather conditions. • A method to apply the equation to building energy simulation is developed and validated. • Implying that the equation and the method have the potential to be applicable to other cities. Abstract The reliable estimation of the urban heat island intensity (UHII) within an urban canopy will benefit a number of fields of research such as urban design, public health, and building energy performance. A diagnostic equation for estimating the daily maximum UHII (UHII max), which is based on routine meteorological data and basic urban properties, was extensively tested with the long-term observations from the metropolis of Nanjing, China. The field measurement has been carried out based on the Local Climate Zone (LCZ) scheme, which is a standardized classification protocol for urban temperature studies. The temperature data set of 658 days collected from six different LCZ classes was used for testing. The results show that the diagnostic equation produced a robust and satisfactory estimation of the daily UHII max under various weather conditions. The overall performance of the equation for Nanjing, that has a root mean squared error (RMSE) of 0.95°C and a median absolute error (MEAE) of 0.60°C, closely approximates its performance for the 14 cities in northwestern Europe (RMSE = 0.91°C, MEAE = 0.58°C). The results also imply that the equation has the potential to be applicable to other cities. Another attempt in this study was to develop a method to apply the diagnostic equation to building energy simulations (BES). The hourly heat island intensities were derived from the estimated UHII max based on the typical diurnal pattern of UHII evolution. An apartment was modeled with the BES program EnergyPlus to examine the validity of the proposed method. Using the modeled and measured temperature data as the inputs in the EnergyPlus simulations, the annual, monthly, and hourly energy demands for cooling and heating were investigated and compared. For all the six LCZ sites except the large low-rise case (LCZ 8), the impacts of the heat island effects at the neighborhood scale on building energy performance were reasonably evaluated with the method. The limitations and perspectives of the equation and its application to BES have also been discussed. [ABSTRACT FROM AUTHOR]

Quantitative real-time observations of a tidal bore in a macro-tidal estuary are difficult and dangerous, particularly in large estuaries. Mathematical and numerical models have been used to predict tidal bore advances; however, to date, there have been no validations of large-scale flow patterns. A marine radar can provide valuable real-time information on tidal bore propagation. In this paper, a template matching method using a cross-correlation algorithm was explored to estimate the evolution and celerity of a tidal bore with medium resolution marine radar images. The Qiantang River tidal bore was recorded at two different geographical locations. Characteristic flow patterns were derived and analysed, including temporal changes over a relatively large-scale area. The experimental results showed that the radar-derived celerity and calculated height of the tidal bore were consistent with visual observations in this estuarine zone. Image 1 • Quantitative real-time observations of a tidal bore in a macro-tidal estuary. • Cross-correlation between successive radar images yield instantaneous bore celerity. • Both magnitude and direction of the bore celerity are derived. • Radar-derived results are validated by visual observations. [ABSTRACT FROM AUTHOR]

Abstract The process of blowing snow is important for secondary distribution of water resources in seasonal grassland snow areas because it affects the regeneration, growth, and nutrient circulation of vegetation. This study conducted field observations of blowing snow and snow accumulation in a grassland area typical of northern China. The results showed that in the near-surface area (0 to 100 cm), snow drifting intensity increased exponentially with a mean wind speed of 2 m/s, and that the maximum snow drifting intensity, which was found within 30 cm of the surface, accounted for 89.61% of the total amount of snow drifting within the near-surface area. The snow drifting intensity was strong under conditions of an abundant snow source and sparse vegetation, with an average value of 2.203 g/cm/min. The snow drifting intensity was lower under conditions of an insufficient snow source and higher vegetation coverage, with an average value of 0.545 g/cm/min. In typical grassland areas with a bare surface and sparse vegetation, snow cover is generally thin; the mean snow depth in such areas during the observation period of this study was 4.03 cm, and this constituted the source of the drifting snow. Snow cover was thicker in areas with taller grass and greater vegetation coverage; the mean value of snow depth in such areas during the observation period was 16.56 cm, and this constituted the main snow cover area. The observation results provide basic data to support the estimation of snow cover amount in grassland ecosystems, optimization of the utilization of snow water resources, regularization of snow cover, restoration of vegetation, and prevention and control of snowstorms. Highlights • The process of blowing snow and snow cover were observed. • The relationship between vegetation and snow cover were surveyed. • Snow areas with a bare surface and sparse vegetation are the primary source areas of blowing snow. • Greater vegetation coverage and height are areas of snow accumulation. [ABSTRACT FROM AUTHOR]

Stomach eversion is common in sharks captured during fishing activities, however, records of subsequent retraction of the stomach once animals are released are rare and limited by the logistics of recording post-release behaviors in the wild. Here, we report stomach eversion and retraction by a tiger shark captured and tagged at Ningaloo Reef, Western Australia. Initial eversion occurred during capture, and retraction was recorded by video and tri-axial acceleration sensors approximately five minutes after release. The ability to retract the stomach without apparent ill effect is consistent with the documented resilience of tiger sharks to stressful capture events, but remains to be confirmed for other species. • Stomach eversion and retraction were recorded by a captured and tagged tiger shark. • Biologging tags documented the energetic stomach retraction behavior. • Stomach retraction is consistent with tiger shark resilience to stressful capture events. [ABSTRACT FROM AUTHOR]

• There is high consistency in the extent of land degradation. • There are consistent hydrothermal change characteristics in the land degradation hotspots area. Land degradation is a major impediment to achieving sustainable development. However, there is currently no harmonized global map of land degradation status and hotspots. This paper aims to obtain the status and hotspots map of global land degradation by multiple methods and indicators to give essential references for land degradation neutrality. The results show that there are significant differences in the distribution and degree of land degradation between the different methods and indicators. Validation through observation points reveals that most of the methods and indicators can reflect land degradation in arid and semi-arid areas, while there are suitable methods or indicators in tropical and high-latitude areas. The degree of degradation has a large difference after overlay analysis, which shows that there are shortcomings of different methods and indicators for monitoring the degree of land degradation. However, the overlay of land degradation extent displays a high consistency, reflecting the current state of global land degradation to a certain extent. These areas with high overlay value can be recognized as hotspots of land degradation. It is also found there are consistent water-energy change characteristics in the hotspot area, such as increased land surface temperature and air temperature and decreased soil moisture and precipitation. These results conclude that studies on the degree of land degradation need to be considered in an integrated manner about the regional background. The combination of multiple methods and indicators is recommended for land degradation extent studies in large areas. Comparison of different methods and indicators is important guidance for global land degradation research. Accelerating ecological monitoring and restoration of land degradation hotspots is the first step towards land degradation neutrality. [ABSTRACT FROM AUTHOR]

Urban energy and carbon exchanges based on the eddy covariance observation over a neighborhood of a humid subtropical city (Guangzhou) were measured from November 2020 to September 2021. The observed urban albedo (average:0.1), median peaks of net all-wave radiation (Q *: 419–563 W m−2) and sensible heat fluxes (Q H : 128–156 W m−2) have small seasonal variabilities, differing from mid-latitude cities (e.g., Shanghai and London) and similar to tropical city (e.g., Singapore). However, latent heat fluxes (Q E) demonstrate a distinct difference between summer (median peak Q E : 131 W m−2, mean daytime Q E / Q* = 27%) and other seasons (median peak Q E < 75 W m−2, mean daytime Q E / Q* = 16%), owing to the synthetic effect of precipitation and radiation. This suggests summer evapotranspiration is significant in cooling such humid cities. For all seasons, the mean daytime Q H / Q* and Q E / Q* are 31% and 22%, causing a mean Bowen ratio of 1.42. The anthropogenic heat flux was substantial (average: 51.6 W m−2), resulting in a larger storage heat flux (median peak Δ Q S : 317 to 357 W m−2, mean daytime Δ Q S / Q * = 67%) than other suburbs or low-rise neighborhoods. Carbon dioxide concentrations and fluxes have similar two-peaks dominated by rush-hour traffic emissions, whereas their seasonality is different. This study is expected to reinforce the global dataset of urban energy exchanges in subtropical cities and evaluate surface-atmosphere exchange processes and urban climate models. • Eddy covariance observation in a compact high-rise zone of a humid subtropical city. • Urban albedo, Q ⁎ and Q H show small seasonal variations in low-latitude cities. • More rainfall and solar radiation in summer cause larger Q E than other seasons. • Cities' larger anthropogenic heat flux leads to higher storage heat flux than suburbs. • CO 2 concentrations and fluxes show daily two-peak patten and different seasonalities. [ABSTRACT FROM AUTHOR]

Highlights • Time-related factors and distances-related factors affect the drivers' deceleration rate choice in Vehicle-Pedestrian conflict have been analyzed. • The drivers' effective decelerating zone with sight angle has been proposed with the consideration of longitudinal & lateral conflict behavior. • Intercultural comparison has been made to address the significant differences in driver behavior in China and Germany. Abstract To analyse the drivers' decelerating behavior in conflict avoidance process under Vehicle-Pedestrian conflict situation is accordingly a surrogate method for the guidance of driver evasive manoeuvre and improving the active driving safety. Field observation data has been collected by video recording and image processing at urban unsignalized midblock crosswalks in Beijng, China and Munich, Germany. The relationship between deceleration rate and vehicle speed has been statistically described. By analyzing how the time-related measures (Vehicle Time to Conflict Point and Pedestrian Time to Conflict Point) and the distance-related measures (Vehicle longitudinal distance to Conflict Point and Pedestrian Lateral distance to Conflict Point) affect the deceleration rate choice, the drivers' effective decelerating zone with sight angle has been proposed with the consideration of longitudinal & lateral conflict behavior. Minimum Vehicle-Pedestrian conflict distance is calculated and a 2 m minimum distance is suggested as the threshold for collision discrimination. Comparisons which address the needs to make the intercultural adaptation when introducing Driver Assistance Systems to developing countries have also been made to show the significant differences between China and Germany. The whole work could hopefully be the groundwork in the target of conflict pre-scanning by decelerating zones under various conflict situations and the design of vehicle active safety systems. [ABSTRACT FROM AUTHOR]

A field observation focusing on reactive oxygen species (ROS) was conducted before, during, and after the 2015 China Victory Day Parade to understand the influence of short-term emissions controls on atmospheric oxidative activity. The hourly average concentrations of PM 2.5 , SO 2 , NO, NO 2 , CO, O 3 , as well as gas and particle-phase ROS, were measured using a series of online instruments. PM 2.5 concentrations during control days were significantly lower than non-control days, which directly lead to the “Parade Blue”, yet reductions of most gaseous pollutants except SO 2 were not so obvious as PM. Similarly, the control measures also led to a great loss of particle-phase ROS throughout the control period, while the reduction of ROS in gas phase was not obvious until the more stringent measures implemented since September 1. Furthermore, only weak positive correlations were observed among ROS and some other measured species, indicating ROS concentrations were affected by a number of comprehensive factors that single marker could not capture. Meanwhile, meteorological condition and regional transportation were also shown to be the minor factors affecting atmospheric oxidizing capacity. The results of this observation mainly revealed the control measures were conducive to reducing particle-related ROS. However, the reduction of gas-phase ROS activity was less effective given the menu of controls employed for the 2015 China Victory Day Parade. Therefore, short-term emissions controls only aimed to PM reduction and visibility improvement will produce the blue sky but will not equivalently reduce the gas-phase ROS. Supplemental control measures will be needed to further reduce gas-phase ROS concentrations. [ABSTRACT FROM AUTHOR]

Bedforms like ripples are widely distributed in the coastal zone. They influence the bed roughness thus the estimation of bed shear stress and associated sediment transport. An echo sounder was mounted on a bottom-supported tripod intended to measure the erosion and deposition of seabed in the subaqueous Yellow River Delta, China. However, variations in bed elevation are found to be not the net erosion or deposition at the observation site, but the migration of silt ripples which were generated by waves and pushed back and forth or flattened off by the tidal currents. Ripple heights were observed to be within 0.1–0.7 cm and were used for testing the model of Nielsen (1981). The model overestimated the height of silt ripples as it was developed for sands, but the deviation can be well addressed by incorporating a linear modification (R 2 = 0.79). Alternatively, a new model specifically for silt ripple height was regressed from the field data with R 2 up to 0.78. The existence of silt ripples increases the bed shear stress by 4 times due to the additional bed roughness. A "fluffy layer" overlies the consolidated seabed, therefore, net seabed erosion occurs after the "fluffy layer" is resuspended. A representative critical bed shear stress for net seabed erosion in the study area was found to be 0.8 Pa. The echo sounder can be an alternative tool for observing silt ripples in coastal regions like the Yellow River Delta where the water is too turbid for underwater videos. The proposed model infers silt-ripple features from bed grain size and flow condition and provides a quick estimate for bed roughness improving the understanding on sediment transport. • A new model for silt ripple height is proposed based on field observation. • Bed shear stress is better estimated by incorporating bed roughness due to silt ripple. • Critical shear stress for erosion is inferred from field observations. • Echo sounder is used for observing silt ripples in turbid waters. • Ripple height is inferred from field-measured bed elevations. [ABSTRACT FROM AUTHOR]

The application of a galloping countermeasure device is one of the main approaches to suppressing galloping and maintaining a stable electricity supply. Loose spacers are a galloping countermeasure for four-bundled conductors that are normally installed in Japan. Loose spacers have two rigid clamps and two rotatable clamps, in contrast to normal-line spacers, which have four rigid clamps. This is expected to suppress galloping by changing the aerodynamic characteristics of the conductors. There are two types of loose spacers: diagonal and one-sided. The former has two rotatable clamps facing each other diagonally. In the latter case, the two rotatable clamps are installed in the upwind side. The galloping-suppression effect of diagonal loose spacers has been demonstrated in previous field observations. Additionally, previous wind tunnel tests proved that one-sided loose spacers are superior to diagonal loose spacers. However, the galloping-suppression effect of one-sided loose spacers and their difference from diagonal loose spacers should be investigated using wind tunnel tests and field observations. In this study, the effectiveness of a one-sided loose spacer and its differences from a diagonal loose spacer were investigated through field observations of four-bundled conductors over eight winter periods. The results showed that one-sided loose spacers were superior to diagonal loose spacers because the maximum tension fluctuation of the conductor with one-sided loose spacers was smaller than that with diagonal loose spacers. However, the galloping of conductors with one-sided loose spacers still occurs in certain situations. Typical galloping is observed when the wind speed is relatively high and the rotational angle of the conductor bundle is relatively large. In this case, the effect of one-sided loose spacers seemed insufficient because the rotational angle of the rotatable clamps was smaller than 80°, which is the limit angle of the equipment. • Galloping-suppression effects of loose spacers were clarified by field observations. • Tension fluctuations can be used as an indicator of galloping amplitudes. • Both one-sided and diagonal loose spacers can suppress galloping in real environment. • The one-sided one is mostly superior to the diagonal one in a single wind direction. • One-sided loose spacers are ineffective when rotatable clamps rotate insufficiently. [ABSTRACT FROM AUTHOR]

• A novel grouting-based bolting technique with lower labor intensity and higher improvement was developed. • The roof is identified as the primary focus of pre-reinforcement for gateroad suffered from front abutment pressure (GFAP). • The application of the grouting-based bolting technique can significantly improve the roadway retaining effect. Longwall roadway suffered from mining-induced abutment pressure caused by the consequent large roof movement is a major concern in underground mining. In this study, a novel grouting-based bolting technique was put forward for Headgate 1404# of Xintian Coal Mine, China. Compared with the traditional support methods of single prop and hydraulic support, the proposed method has the advantages of low labor intensity and high improvement of surrounding rock. The field investigation on the effect of mining-induced abutment pressure on the roadway and calibrated numerical models on parameter verification are the key technical design of the proposed grouting-based bolting method. The field investigation showed that in the range of 0–30 m from the faceline, roof-to-floor convergence and roof fracture of the roadway were significant, which affected the stability of the roadway. In our designed scheme, grouting anchor cable was employed for roof pre-reinforcement through grouting the cement and sodium silicate into the roof; the grouting depth was 8 m, and the grouting position was 30 m ahead of the mining operation. The reliability of this scheme was verified by the comparison of stress field, skin convergence, rock fracture and grouting diffusion via the numerical simulation. The simulation results show that after applying grouting-based bolting, the range of maximum principal stress reduction, deformation and the fractured zone around the roadway is smaller than that of the traditional single support. Compared with the traditional method, the convergence of roof-to-floor and rib-to-rib after the implementation of the proposed method decreases by 64.5 % and 82.0 %, and the fracture depth of the roof and ribs decreases by 66.4 % and 38.2 %, respectively. The proposed grouting-based rock bolting significantly improves the resistibility of roadway surrounding rock to the mining-induced abutment pressure, which is beneficial for roadway retaining after mining. [ABSTRACT FROM AUTHOR]

The Pamir Plateau at the western end of the India–Asia collision zone underwent long-term terrane drifting, accretion and collision between early Paleozoic and Mesozoic. However, the detailed evolution of this plateau, in particular, the timing of the Proto- and Palaeo-Tethys ocean subduction and closure, remains enigmatic. Here we report new field observations and zircon U-Pb ages and Hf isotopic compositions of the representative rocks from the so-called Precambrian basement in the northeastern Pamir, i.e., the Bulunkuole Group. The rock associations of the Bulunkuole Group indicate volcano-sedimentary sequences with arc affinities. Geochronological data demonstrate that the deposition age of the Bulunkuole Group in the NE section of the Pamir was Middle to Late Cambrian (530–508 Ma) rather than Paleoproterozoic. The deposition age became progressively younger from south to north. The amphibolite- to granulite facies metamorphism of the Bulunkuole Group took place at ca. 200–180 Ma. Unlike the scenario in the Southern Kunlun terrane (SKT) in the eastern section of the West Kunlun Orogenic Belt (WKOB), early Paleozoic metamorphism (ca. 440 Ma) was absent in this area. Two phases of magmatic intrusions, composed of granites and minor gabbros with arc geochemical signatures, emplaced at 510–480 Ma and 240–200 Ma. The amphibolite (meta mafic sheet? 519 Ma) and the meta-rhyolite (508 Ma) have zircon εHf(t) values of 1.6 to 5.9 and − 1.5 to 1.4, respectively. The 511 Ma gneissic granite sheet and the 486 Ma gabbro have zircon εHf(t) values of − 0.1 to 2.4 and 1.3 to 3.6, respectively. Zircon εHf(t) of the 245 Ma augen gneissic granite sheet varies from − 2.2 to 2.0 whereas the metamorphic zircons from the amphibolite (193 Ma) and high-pressure mafic granulite sample (187 Ma) have negative εHf(t) values of − 5.3 to − 2 and − 15 to − 12, respectively. In line with rock association and the deposition age of the Bulunkuole Group and the Saitula Group in the eastern section of WKOB, we propose that both of them were accretionary wedge between the Tarim and Tianshuihai terrane formed during the Proto-Tethys ocean south- southwestward subduction (present orientation). The timing of deposition and metamorphism documents two distinct phases of arc magmatism and sedimentary basin evolution. This indicates that the Proto-Tethys ocean closed at ca. 440 Ma in the eastern section of WKOB whereas in the western section, a remnant of the Proto-Tethys ocean between the Tarim and the NE Pamir did not close till Late Triassic. This remnant ocean was filled by the Ordovician-Triassic sequences. The accretion between NE Pamir and the Central Pamir was completed by ca. 180 Ma as demonstrated by the metamorphic zircon U-Pb age of the high pressure mafic granulite in the NE Pamir. [ABSTRACT FROM AUTHOR]

The thermal status of the rock surrounding tunnel will change during construction and operation periods in cold regions, thereby affecting the stability of tunnel. Field observations of thermal regime of a permafrost tunnel were conducted on Tibetan Plateau. The results show that during the past 12 years, the surrounding rock experienced a warming that subsequently returned to the natural thermal regime, and that was followed by a cooling process. The thermal disturbance distance of the surrounding rock was approximately 30.5 m after the construction. Compared with the air temperature outside the tunnel, heat source of the construction has a great influence on the temperature of the permafrost surrounding the tunnel. The temperature of the permafrost is sinusoidally varying, which achieves a steady state after twelve freeze–thaw cycles. The mean annual ground temperature of the permafrost, and the maximum and minimum temperature amplitudes decreased with time. The heat convection between the air in the tunnel and the surrounding rock during the operation of trains needs to be considered for the design of the permafrost tunnel that could gradually reduce the temperature of the permafrost. The permafrost tunnel could occur to freeze–thaw damage for the sections that lack laid insulation material. [ABSTRACT FROM AUTHOR]

The Local Climate Zone (LCZ) scheme aims to provide an objective and standardized classification protocol for urban temperature studies in any city. The field observed temperature data from 12 selected LCZ sites in Nanjing, China, for the period from July to November 2016, was used to evaluate the LCZ scheme. The results here are the first to assess the LCZ scheme in a high-density city in mainland China. Distinct thermal differences among the LCZ sites provide preliminary evidence to support that the LCZ concept is applicable for urban temperature studies in cities of China. [ABSTRACT FROM AUTHOR]

A diagnostic equation for the urban heat island (UHI) effectwas evaluated by field observations in Nanjing, China. It is the first time for the equation to be evaluated in a city outside of Europe. The field observation was carried out based on the Local Climate Zone (LCZ) scheme, which aims to provide an objective and standardized classification protocol for urban temperature studies in any city. The diagnostic equation was tested for 7LCZ types under different weather conditions during the period from July to November 2016. The results show that the equation is capable of diagnosing the daily maximum UHI with an acceptable level of accuracy ( r 2 =0.46, RMSE =1.08 K, MEAE =0.76 K). [ABSTRACT FROM AUTHOR]

The impact of urban heat island on building cooling load is assessed based upon the Local Climate Zone (LCZ) scheme. The field observed data from the nine LCZ sites in Nanjing, China, for the period from 21 July to 30 September 2016 were used to generate new EnergyPlus Weather (EPW) files. Then the cooling loads of a typical office building and apartment building were simulated with EnergyPlus. The heat island features of the LCZs and their impacts on building cooling load were analyzed. For the whole studied period, the cooling load increases for the office building and the apartment building range between 4.0%–7.1% and 11.2%–25.2%, respectively. For the night time (19:00–06:00) of the 22 identified days with the weather condition of light winds and clear skies, the cooling load increases of the apartment building range from 12.8% to 52.5%. [ABSTRACT FROM AUTHOR]

To analyse the damage characteristics of thermosyphon embankments in a permafrost region, the Qingshui River section along the Qinghai-Tibet Highway (QTH) was used as a case study in which a field investigation and drilling were performed. The field soils were sampled, and their water content, dry density and compaction degree were tested in the laboratory. Based on the measured temperature data of the thermosyphon embankment, damage characteristics and possible associated causes were analysed. The major damage found in thermosyphon embankments was a longitudinal crack, which developed 1.0 to 2.0 m away from the thermosyphon. In partial sections, waves and other damage also occurred. The damage was primarily attributed to the non-uniform temperature distribution, which resulted in a non-uniform distribution of the mechanical properties of the embankment filling. Under a heavy traffic load, stress concentration phenomena occurred at the freezing-thawing interface that gradually developed into a longitudinal crack with increased highway operation. The embankment damage history, rainfall seepage, ponding near the embankment and freezing-thawing cycles further accelerated the development of damage along the thermosyphon embankments. According to the characteristics and causes of thermosyphon embankment damage, precisely computing the cooling efficiency of thermosyphon in the design stage is necessary to prevent freezing-thawing interface waves resulting from excessive cooling effectiveness, to reduce thermal erosion from ponding near the embankment by improving embankment drainage systems, and to set necessary structural measures at thermosyphon embankments that can improve their strength. [ABSTRACT FROM AUTHOR]

Dune movement processes are affected by various sand transport processes, especially at the dune crest; however, there are relatively few field measurements on this issue. In this paper, 76 field measurements were collected over a dune crest at the Shapotou Aeolian Experiment Site, northeastern Tengger Desert, China to measure the rate of sand transportation under filed conditions. The measured sand transport rate ranged from 0.2 to 121.2 kg m −1 h −1 , and most (95%) were less than 67 kg m −1 h −1 . The roughness length calculated from the wind profiles was much larger than the results of previous studies. A linear regression analysis indicated that the modified Charnock model gives the best relationship fit between the shear velocity and roughness length ( C m = 0.432, n = 76, p < 0.0001, R 2 = 0.997). The sand transport flux over the dune crest can be expressed as an exponential function and a Gaussian function. A correlation coefficient analysis of the complex relationship between the sand transport and wind conditions (mean velocity, maximum wind velocity, shear velocity, potential sand transport, and wind direction) and the surface properties (roughness length, fetch length) indicated that the sand transport rate over the dune crest is positively correlated with the mean velocity ( n = 76, p < 0.0001, R 2 = 0.58) and shear velocity (n = 76, p < 0.0001, R 2 = 0.57) and is negatively correlated with the wind direction ( n = 76, p < 0.0001, R 2 = −0.37). The wind direction affects sand transport over the dune crest and the coefficients of the sand transport flux. The critical wind direction is 272°, which is approximately perpendicular to the line of the crest (37°). [ABSTRACT FROM AUTHOR]

This work presents a three-year continuous observation of ozone (O 3) and fine particle (PM 2.5), as well as their precursors in Qingdao, China, from September 2018 to August 2021. The annual concentrations of O 3 and PM 2.5 were measured as 35.9–44.5 ppbv and 31.6–34.2 μg m−3, respectively. Analysis of the interannual variations of O 3 and PM 2.5 concentration indicated the effective control measures for PM 2.5 and O 3 pollution in Qingdao in recent years. Nevertheless, we still observed 85 O 3 episodes and 80 PM 2.5 episodes during the whole observation. And it was found that the fraction of secondary inorganic aerosols (SIA) in PM 2.5 mass significantly increased during PM 2.5 episodes. By employing the Lagrangian photochemical trajectory model (LPTM), we investigated the roles of local production and regional transport (i.e., short-distance transport and long-distance transport) that play in the O 3 and SIA formation in these episodes. The contribution of local production, short-distance transport, and long-distance transport to O 3 concentration was calculated as 36%, 25%, and 39%, respectively. Long-distance transport seemed to play a more significant role in the SIA formation, accounting for 56% of SIA concentration. Moreover, the calculation results of the relative incremental reactivity (RIR) showed that both O 3 and SIA formation were mainly affected by NO x and VOCs emissions during the process of long-distance transport. The observed unexpectedly high contribution of long-distance transport to O 3 and SIA formation suggests that more extensive regional joint prevention and control policies on NO x and VOCs emissions are warranted to mitigate secondary air pollution. • PM 2.5 concentration had little change while O 3 concentration decreased from 2018 to 2021 in Qingdao. • Long-distance transport played a significant role in O 3 and SIA formation in Qingdao. • O 3 and SIA formation were mainly affected by NO x and VOCs emissions during the long-distance transport processes. [ABSTRACT FROM AUTHOR]

The evolution process of ephemeral gully (EG) is a major content in the study of gully erosion and geomorphology. However, due to the short duration of EG existence, field-based continuous quantitative observation information is still lacking. The objective of this study was to characterize the morphological changes and evolution mechanisms of EG under natural conditions in the Dry-hot Valley. A representative EG was observed from 2016 to 2020 by using laser scanning. Results showed that after four years, the erosion area and erosion volume increased 4.5 and 17.3 times, respectively. The length, width, and depth of the main channel continuously increased over time but the growth rates decreased. During the four monitoring periods, the average growth rates of width were 0.12, 0.26, 0.33 and 0.06 m/year, respectively; the average growth rates of depth were 0.07, 0.08, 0.03 and 0.02 m/year, respectively; and the growth rates of length were 7.58, 1.78, 2.17 and 1.17 m/year, respectively. EG morphological parameters varied at different locations of the hillslope. The cross-section area increased gradually towards downslope, especially in the middle and lower parts of the channel. However, the width-depth ratio of EG decreased gradually from upper to lower parts of the hillslope, and the values were generally greater than 1.0. In addition, the variation of sinuosity, density and tortuosity complexity were influenced by both headward and lateral erosion, which increased and then decreased. The vertical gradient increased significantly and then tends to be stable. The results of this study are helpful to enrich current studies on the evolution process of ephemeral gully. • Microtopographic factors have significant impacts on EG channel development. • Cross-section parameters can reveal the morphological evolution from rill to EG. • Soil erosion-deposition characteristics in the EG channel differed annually. • Slope range in the EG area presented a normal distribution with channel growth. [ABSTRACT FROM AUTHOR]

As the nation’s bread basket, Northeastern China has experienced dramatic land use changes in the past decades, with much natural land being converted into cropland to feed the growing population. The long dormant season, coupled with frequent cold fronts and strong spring winds, makes the exposed cropland vulnerable to wind erosion. However, the rates and spatial–temporal characteristics of wind erosion in this particular soil type have been poorly studied. The present study aimed to measure and simulated the wind erosion characteristics from black soil cropland in the Dehui region of Northeastern China. Our results showed that wind-blown erosion was positively correlated with wind speed and negatively linked to soil moisture, vegetation and soil roughness in this region. The measured threshold friction velocity was 4.47 m/s at 2 m height, corresponding to 0.37 m/s at the surface ground. Based on WRF-CMAQ-FENGSHA model, we localized the parameters and simulated a significant wind erosion event in the Dehui region on May 31, 2013. The relationships between modeled dust flux and ground measurement were correlated ( R 2 = 0.78). In addition, the modeled aerosol optical depths were also captured by satellite observations (MODIS and CALIPSO). Our results indicate that the bare farmland areas over Northeastern China are important dust sources over this region, and should not be neglected in regional air quality models. The use of protective farming techniques, protection of grassland and plowing in autumn for cropland areas should be considered to combat dust emission. [ABSTRACT FROM AUTHOR]

The photochemical formation of alkyl nitrates (RONO 2 ) and their impact on ozone (O 3 ) formation were investigated using a Photochemical Box Model incorporating the Master Chemical Mechanism (PBM-MCM). The model was constrained with field measurement data collected on selected O 3 episode days at Tai O, a rural-coastal site in southwestern Hong Kong, from August 2001–December 2002. The in-situ observations showed that the sum of C 1 –C 5 RONO 2 varied from 30.7 ± 14.8 pptv in spring to 120.7 ± 10.4 pptv in autumn, of which 2-butyl nitrate dominated with the highest average concentration of 30.8 ± 2.6 pptv. Model simulations indicated that the pathway of CH 3 O reacting with NO 2 , proposed in our previous study, made minor contributions (11.3 ± 0.7%) to methyl nitrate formation. Indeed, 51.8 ± 3.1% and 36.5 ± 6.3% of the methyl nitrate was attributed to the reaction of CH 3 O 2 +NO and to oceanic emissions/biomass burning, respectively. For the C 2 –C 5 alkyl nitrates, the contribution of photochemical formation increased with increasing carbon number, ranging from 64.4 ± 4.0% for ethyl nitrate (EtONO 2 ) to 72.6 ± 4.2% for 2-pentyl nitrate (2-PenONO 2 ), while the contribution of oceanic emissions/biomass burning decreased from 35.1 ± 6.5% for EtONO 2 to 26.8 ± 6.8% for 2-PenONO 2 . Model simulations of photochemical O 3 levels influenced by RONO 2 chemistry showed that the formation of methyl-, ethyl-, i -propyl-, n -propyl-, 2-butyl-, 2-pentyl-, and 3-pentyl-nitrates led to O 3 reduction of 0.05 ± 0.03, 0.05 ± 0.03, 0.06 ± 0.02, 0.02 ± 0.02, 0.18 ± 0.04, 0.09 ± 0.02 and 0.06 ± 0.02 ppbv, respectively, with an average reduction rate of 11.0 ± 3.2 ppbv O 3 per 1 ppbv RONO 2 formation. The C 1 –C 5 RONO 2 constituted 18.6 ± 1.9% of the entire RONO 2 , and had a nitrogen reserve of 4.1 ± 0.2%, implying their potential influence on O 3 production in downwind areas. [ABSTRACT FROM AUTHOR]

On a coral reef coast near Point Kin located in central Okinawa, a large-scale excavation of the sandy beach was carried out by the American armed forces after WWII and sandy beach disappeared. However, after the excavation, the sandy beach was rapidly recovered. In this study, the rate of sand supply from the reef was estimated on the basis of change in foreshore area after the excavation of the shoreline area by using aerial photographs. It was concluded that sand supply of 0.5-0.8 m 3 /m/yr could be anticipated in the long term. [ABSTRACT FROM AUTHOR]

• 34 days of in situ monitoring of natural flooding processes in the Yangtze River confluence show that the distribution of supersaturated dissolved gas in the confluence area is influenced by both mainstream and tributary. • Combining monitoring data with numerical simulation techniques to develop a depth-averaged two-dimensional numerical model for the natural river confluence that can effectively predict the transport and distribution of supersaturated gas. • Flow-weighted pollution transport models can roughly calculate the supersaturation in water when the mainstream and tributaries are complete mixed but the details of distribution require fine modelling. • The existing low saturation zone in the mixing area created by the tributaries where the saturation follows the tributaries. The area of the region is positively correlated with the proportion of tributary flow and inversely with mainstream saturation. Confluences are common habitats of ecological significance given their complicated hydraulic structures and mass transportation. In hydropower cascades, dissolved gas supersaturation downstream of a dam becomes a negative environmental impact caused by dam spilling, which may cause fish to suffer from gas bubble disease and even death. A difference in the supersaturation level of dissolved gas is consistently noted between the mainstream and tributaries mainly due to their different cascade developments and dam scales, resulting in a significant nonuniform distribution of dissolved gas at a confluence. This study focused on describing the hydrodynamics and dissolved gas distributions under unsteady inflows at an actual confluence of the Min River and Jinsha River in China. A long period of prototype observations on dissolved oxygen (DO) were conducted to demonstrate DO variation at the confluence and calibrate the DO dissipation coefficient. A depth-averaged two-dimensional numerical model was developed that reflects the nonconstant characteristics of flow and supersaturated DO at the confluence and was verified to be in good agreement with the measured data series. The supersaturated DO level at the confluence increases as the inflow DO level of the mainstream Jinsha River increases and decreases as the flow ratio of the branch Min River and Jinsha River increases, representing two aspects influencing the distribution of DO at the confluence. A comparison was performed to evaluate the DO saturation calculation method when DO was laterally mixed downstream of the confluence. The accuracy of the flow weighted average calculation based on the data of the mainstream and a tributary upstream of the confluence was acceptable, but the simulation method was recommended to obtain a refined distribution and spatial utilization of supersaturated DO at the confluence when it was necessary to pay more attention to the ecological function in this region. A two-dimensional unsteady numerical model based on valuable prototype observations was proposed, which provides technical tools for characterizing the hydrodynamics and dissolved gas variations and distributions at confluences and better evaluating the risk for fish in regions of great ecological significance. [ABSTRACT FROM AUTHOR]

Highlights: [•] The power n in the relationship between vertical dust flux and friction velocity depends on particle size. [•] The n values were 2.54 (0.7μm), 3.40 (1.1), 3.80 (1.7), 4.32 (2.6), 4.67 (4.6), and 4.53 (7.0). [•] A shorter average time such as 1-min mean is applicable for dust flux measurement. [•] Particle size distributions of dust concentration at different heights had a similar shape. [Copyright &y& Elsevier]

• The instability mechanism of the landslide is clarified. • Anchor cable reinforcement is applied to prevent slope failure. • Double side-wall heading method is used for portal excavation under collapse condition. • Research results show that the treatment methods worked effectively. • Lessons learned from this incident have been presented. This paper reports a collapse accident of slope instability at the entrance of Taizhen Tunnel in Qujiang Section of Hangxinjing Expressway in China. The landslide instability mechanism was studied by field observation and testing. Considering the stability of the landslide and the disturbance effect of secondary tunneling construction, comprehensive reinforcement measures were proposed. The monitoring data showed that good results were achieved. In addition, the effectiveness analysis of the treatment scheme was further examined via numerical simulation. The analysis results show that slope reinforcement before tunnel excavation can not only prevent slope failure but also reduce the deformation of the supporting structure. The improved double side-wall heading method has less disturbance to the slope and is more conducive to the overall stability of the slope. Finally, the lessons learned were summarized, providing insights for preventing future similar incidents from reoccurring. [ABSTRACT FROM AUTHOR]

• A newly developed installation technology of LDDB caissons is reported. • Twin LDDB caissons are installed in undrained ground with stiff clays using new technology. • Field performance of twin caissons is monitored in real-time. • Installation effects and interaction of twin caissons are comprehensively assessed. The development of installation technologies of open caissons has been lagging behind increasingly complex construction conditions. For such purpose, a new installation technology of large diameter deeply-buried (LDDB) open caissons has been developed and then used for construction of twin LDDB caissons into undrained ground with stiff soils in Zhenjiang, China. To assess the installation effects and filed performance, a monitoring program was presented to document the variations in total jacking forces provided by new shaft driven method, ground water level (GWL) around the caisson shaft, inclination angles of caisson shafts and radial displacements of surrounding soils as well as surface settlements of existing nearby facilities. It is observed that the monitoring data during the installation falls almost entirely within the design criteria, the reported new technology has limited impacts on the induced ground movements, depending on the variation in GWL, interaction between twin caissons and excavation-induced unloading effect. Moreover, the total jacking forces increase approximately in stepwise shape as the installation depth increases; the change law of surface settlements is highly similar to those of GWL, showing their close correlation; the larger inclination angles of caisson shafts are mainly encountered in the earlier installation phase, but well controllable. Further discussion on ground movements caused by various technologies confirms the feasibility of new installation technology. Both the observed and compared results give greater confidence on the use of such the technology in practice. [ABSTRACT FROM AUTHOR]

Abstract: Since the mean wind profile in the tropical cyclone boundary layer is important in both the fields of meteorology and wind engineering, the wind measurements taken during the passages of several tropical cyclones or typhoons in Hong Kong by the wind-profilers and the Doppler Sonic Detection And Ranging (SODAR) have been utilized to calculate both the hourly and 10-min mean wind profiles. These observed profiles were then fitted to the log-law, the power-law and an empirical profile model taking into consideration the low-level jet. The results showed that the low-level jet, which is commonly observed for the mean wind profile in the tropical cyclone boundary layer over the sea, was not found. In addition, we found that the surface roughness derived by fitting the observed profile to the log-law was unusually high (). The possible explanations include (1) the influence of large scale topography and (2) the high waves introduced by strong typhoon winds. [Copyright &y& Elsevier]

Abstract: Tsunamis, or “harbor waves” in Japanese, are so-named due to common observations of enhanced wave heights, currents and damage in harbors and ports. However, dynamic currents induced by these waves, while regularly observed and known to cause significant damage, are poorly understood. Observations and modeling of the currents induced by the 2011 Tohoku and 2004 Indian Ocean tsunamis allows us to show that the strongest flows in harbor basins are governed by horizontally sheared and rotational shallow features, such as jets and large eddies. When examining currents in harbors, this conclusion will generally require a simulation approach that both includes the relevant physical processes in the governing equations and uses a numerical scheme that does not artificially damp these features. Without proper representation of the physics associated with these phenomena, predictive models may provide drag force estimates that are an order of magnitude or more in error. The immediate implementation of this type of analysis into tsunami hazard studies can mean the difference between an unaffected port and one in which 300m long container vessels are detached from their moorings and drift chaotically. [Copyright &y& Elsevier]

Abstract: The present study aimed to evaluate an experimental approach to individually assess social reactivity among sheep. INRA401 male lambs (n =163) were reared together outdoors as part of a larger flock. Fifteen days after weaning the animals were individually exposed to an arena test of 2 phases (1-social attraction, 2-social isolation) during which proximity toward conspecifics and vocal and locomotor reactivity were measured. One day after the test their inter-individual distances were measured when grazing over a 2-h period in order to estimate their sociability on pasture. This was made using scan sampling recording the identity of the nearest neighbour for each individual, which led to the establishment of a sociability index. Overall, we found that high-pitched bleats recorded during the attraction phase (r =0.22) and the isolation phase (r =0.23) of the arena test as well as the locomotor activity measured during the isolation phase (r =0.27) were positively correlated with the sociability index. Furthermore, the behaviour of lambs during the isolation phase of the arena test (i.e. vocal and locomotor agitation) appeared to be a significant predictor explaining 13% of the variance of the sociability on pasture. The behavioural reactivity measured through the arena test thus reflects at least to some extent the sociability of sheep. Those results are very encouraging as they suggest that the sociability of lambs could indeed be evaluated through a short experimental test, which is less time consuming than field ethological observations. [Copyright &y& Elsevier]

Abstract: Few studies have been conducted on modeling boulder transport by tsunamis despite considerable research on the analysis of boulder deposits. A detailed description of the derivation of governing equations for boulder transport in submerged, partially submerged, and subaerial (not in contact with fluid) is presented, and then a numerical model is proposed to solve the governing equations in one dimension. Subsequently, the model is used to analyze the transport of calcareous boulders detached from a seawall in Lhok Nga (northwestern Sumatra, Indonesia) by the 2004 Indian Ocean tsunami. A few simulated transport distances match field observations, but the others are higher than the field measurements. Clast-to-clast interactions at the inception of transport would have a major impact on changes in transport distance, dissipating the energy in impulses as destruction of the seawall releases different sizes of boulders with different velocities. Moreover, surface microtopographical effects could completely stop the transport prematurely. The difference between the simulated results and the field observations is partly attributed to limitations of the numerical model. No landward fining was observed in the field measurements, but numerically predicted results showed a reasonable trend of landward fining. [Copyright &y& Elsevier]