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Low-level jets (LLJs) are defined as regions of anomalously high wind speeds occurring within the first kilometre of the troposphere. They are filamentous structures that are usually strongly related to moisture transport. This study analysed the moisture transport associated with LLJs, and the role of LLJs in precipitation events that occasionally lead to extreme precipitation and major floods. A daily climatology dataset of nocturnal LLJs was developed and moisture transport was studied by analysing the source and sink regions. A nocturnal LLJ index based on the vertical structure of temporal wind variations was applied, and a total of 33 nocturnal LLJs were identified and characterised. The FLEXPART Lagrangian model was then used to simulate jet behaviour and to identify major source and sink regions during the period from 1980 to 2016. Differences between days with LLJs and days with no LLJs were subsequently calculated for each LLJ on a global scale with respect to moisture transport for the sources and sinks of moisture. Finally, each LLJ was analysed in terms of its associated socioeconomic impact and relationship with water scarcity.

In this paper, examples of all types of signal injection such as different signal , harmonic signal and multiple signal injections in a TWT including hollow electron beam near frequency 1800 MHz and within input powers lower than TWT saturation power has been analyzed using approximate analytical solution of S-MUSE model. Later, the results obtained from approximate analytical solution with large signal code LATTE, that is a Lagrangian model, have been tested and simulated so that the effect of input phase difference between drive and injected wave and the effect of input powers on the amplification value of drive and generated second-order harmonic waves were investigated. The phase difference between drive and harmonic waves is a key parameter in harmonic injection for increasing the output power of drive and second-order harmonic frequencies.

The first ever long-term measurement of black carbon (BC) aerosols over an urban location at the central Indo-Gangetic Plain (IGP) is presented. Both short- and long-term variations in BC during the period 2009-2013 are discussed with specific emphasis on variation in BC sources, meteorology, trend and possible transport pathways across the IGP. High BC mass loading was noted with a 5-yr composite mean (± SD) of 11.8 (± 8.6) µg m –3 , having strong and consistent seasonal variations (median: 8.8; range: 1.4-48.0 µg m –3 ). Winter (21.5 ± 9.9µ gm –3 ) and post-monsoon (17.4 ± 10.2 µg m –3 ) specific rises in BC mass were consistent with the increase in household emissions, and from agricultural residue burning. The BC mass concentration was mostly influenced by local sources, while sudden change in BC was consistent with the change in Delta-C, indicating emissions primarily from biomass burning. Beside sources, atmospheric boundary layer height was noted to considerably influence short-term variations in BC concentration. A statistically significant monotonic increasing trend in BC concentration (0.9 µg m –3 yr –1 ) was computed along with its 95% uncertainty bounds (0.38-1.52 µ gm –3 yr –1 ). Increase in BC concentration was consistent with a rise in BC sources across the IGP and over India. Furthermore, clear evidence of local and regional scale transport of BC aerosols was found using the particle Lagrangian model.

In the present study, numerical simulations are carried out to understand the combustion characteristics of lifted spray flames for various coflow conditions. Flame structure, lift-off char...

Given the crucial role of low-level circulation in convective events, this study presents a climatological characterization of the moisture sources and sinks associated with the occurrence of nocturnal low-level jets (NLLJs) in South America. Six selected NLLJ cores are identified according to the jet index that considers a vertical wind speed shear of the lower troposphere at 00:00 local time (LT). The Lagrangian FLEXible PARTicle (FLEXPART) model was used to provide the outputs for tracking atmospheric air masses to determine the moisture sources and sinks for the NLLJ cores (Argentina, Venezuela, and the regions of Brazil: south—Brazil-S, southeast—Brazil-SE, north—Brazil-N, and northeast—Brazil-NE). The analysis is based on 37 years (1980–2016) of the ERA-Interim reanalysis. We found that the NLLJ index is stronger in the warm periods of a year (austral spring and summer) for the six selected regions. The NLLJ frequency is also higher in the warm months of the year, except in Brazil-NE where it is very frequent in all months. In Brazil-NE, the NLLJ also persists for 8 or more days, while the other NLLJs frequently persist for 1–2 days. The NLLJs occupy a broad low-level layer (from 1000 to 700 hPa) and exhibit a mean speed between 7 and 12 ms–1, which peaks mostly at 900 hPa. The moisture transport for each NLLJ shows that in addition to the intense local moisture sources, the NLLJs in Argentina and Brazil-S receive moisture from the tropical-subtropical South Atlantic Ocean and the Amazon basin, while the tropical-subtropical South Atlantic Ocean is the main moisture source for the NLLJ in Brazil-SE. Both moisture sources and sinks are stronger in the austral summer and fall. The NLLJ in Brazil receives moisture from the tropical South Atlantic (TSA) Ocean, which has weak seasonality. The moisture sources for the NLLJs in Brazil-N and Venezuela come from the tropical North Atlantic (TNA) Ocean in the austral summer and fall, while the TSA Ocean appears as an additional moisture source in the austral winter. This research contributes to improving our understanding of the NLLJs and their role in transporting moisture and controlling precipitation over the continent according to the seasons of a year, helping to improve seasonal climate forecasting. Agencia Estatal de Investigación | Ref. RTI2018-095772-B-I00 Ministerio de Economía y Competitividad | Ref. CGL2015-65141-R Xunta de Galicia | Ref. ED431C 2017/64

A Lagrangian model which describes radionuclide transport in the northern Indian Ocean is described. Water circulation is obtained from HYCOM ocean model for year 2017. The model includes advection by currents, turbulent mixing and radionuclide interactions between water and sediments, described in a dynamic way using kinetic transfer coefficients. Hypothetical releases from five coastal nuclear power plants operating in the northern Indian Ocean were simulated. Releases were supposed to start both during the winter and summer monsoons, to study reversing circulation effects. Age distributions of releases were calculated, which adds information about circulation and radionuclide pathways. It was found that, for some of the NPPs, radionuclide distributions resulting from releases starting in both seasons were not as different as could be expected from the opposed circulation schemes during each monsoon. Effective 137Cs half-lives in the ocean surface were calculated and results were two orders of magnitude below previous estimations.

Computational modeling allows studying the air quality problems in depth and provides the best solution reducing the population risks. This research demonstrates the Graz Lagrangian model effectiveness for assessing emission sources contributions to the air pollution: particles tracking and accumulation estimate. The article describes model setting up parameters and datasets preparation for the analysis. The experiment simulated the dispersion from the main groups of emission sources for real weather conditions during 96 h of December 2018, when significant excess of NO2, CO, SO2, PM10, and benzo(a)pyrene concentrations were observed in the Krasnoyarsk surface atmospheric layer. The computational domain was a parallelepiped of 40 &times, 30 &times, 2.5 km, which was located deep inside the Eurasian continent on a heterogeneous landscape exaggerated by high-rise buildings, with various pollutions sources and the ice-free Yenisei River. The results demonstrated an excellent applicability of the Lagrange model for hourly tracking of particle trajectories, taking into account the urban landscape. For values &lt, 1 MPC (maximum permissible concentration) of peak pollutants concentrations, the coincidences were 93 cases, and for values &lt, 0.1 shares of MPC, there were 36 cases out of the total number of 97. The same was found for the average daily concentration for values &lt, 1 MPC&mdash, 31, and for values &lt, 0.1 MPC&mdash, 5 matches out of 44. Wind speeds COR&mdash, 65.3%, wind directions COR&mdash, 68.6%. The Graz Lagrangian model showed the ability to simulate air quality problems in the Krasnoyarsk greater area conditions.

Short-term events are one of the specific aspects that differentiate odour nuisance problems from conventional air quality pollutants. Atmospheric dispersion modelling has been considered the gold standard to realise odour impact assessments and to calculate separation distances. Most of these models provide predictions of concentrations of a pollutant in ambient air on an hourly basis. Even when the hourly mean odour concentration is lower than the perception threshold, concentration peaks above the threshold may occur during this period. The constant peak-to-mean factor is nowadays the most widespread method for evaluating short-term concentrations from the long-term ones. Different approaches have been proposed in the scientific literature to consider non-constant peak-to-mean factors. Two prominent approaches to do so are the i) variable peak-to-mean factor which considers the distance from the source and atmospheric stability and the ii) concentration-variance transport. In this sense, the aim of this work is to compare the results of three different freely available dispersion models (namely, CALPUFF, LAPMOD and GRAL), which implement three distinct ways to evaluate the short-term concentration values. Two sites, one in Austria and the other in Italy, were selected for the investigation. Dispersion model results were compared and discussed both in terms of long-term (hourly) concentrations and short-term. An important outcome of this work is that the dispersion models provided more equivalent results for hourly mean concentrations, in particular in the far-field. On the contrary, the method to evaluate short-term concentrations can deliver disparate results, thereby revealing a potential risk of poor assessment conclusions. The utilistion of a multiangle methodological approach (dispersion models, study site locations, algorithms to incorporate short-term concentrations) allowed providing useful information for future studies and policymaking in this field. Accordingly, our findings call for awareness on how the use of a particular dispersion model and its sub-hourly peak calculation method can affect odour impact assessment conclusions and compliance demonstrations.

Aircraft atmospheric profiling is a valuable technique for determining greenhouse gas fluxes at regional scales (104&ndash, 106 km2). Here, we describe a new, simple method for estimating the surface influence of air samples that uses backward trajectories based on the Lagrangian model Hybrid Single-Particle Lagrangian Integrated Trajectory Model (HYSPLIT). We determined &ldquo, regions of influence&rdquo, on a quarterly basis between 2010 and 2018 for four aircraft vertical profile sites: SAN and ALF in the eastern Amazon, and RBA and TAB or TEF in the western Amazon. We evaluated regions of influence in terms of their relative sensitivity to areas inside and outside the Amazon and their total area inside the Amazon. Regions of influence varied by quarter and less so by year. In the first and fourth quarters, the contribution of the region of influence inside the Amazon was 83&ndash, 93% for all sites, while in the second and third quarters, it was 57&ndash, 75%. The interquarter differences are more evident in the eastern than in the western Amazon. Our analysis indicates that atmospheric profiles from the western sites are sensitive to 42&ndash, 52.2% of the Amazon. In contrast, eastern Amazon sites are sensitive to only 10.9&ndash, 25.3%. These results may help to spatially resolve the response of greenhouse gas emissions to climate variability over Amazon.

We study influence of scalar fields on nonlinear electrodynamics spacetimes. The investigation is carried out using both test and gravitating scalar fields. After revisiting Einstein--Maxwell scalar field solutions we focus on analytic investigation of nonlinear electrodynamics scalar field spacetimes, especially the square root Lagrangian model. The main motivation being to understand whether certain specific signatures of scalar fields are preserved when nonlinear electrodynamics as an additional source is considered. We show that the regularity of horizon which is spoiled by scalar field in spherically symmetric static scalar-vacuum spacetimes is not improved by including nonlinear electrodynamics or other sources satisfying certain condition. We confirm these findings using test scalar field that enables us to go beyond spherical symmetry.

Two radionuclide transport models for the Red Sea are described: a Lagrangian model to deal with emergency situations and a Eulerian model better suited to longer term simulations, as for instance required in case of chronic radionuclide releases. Baroclinic circulation is obtained for both transport models from HYCOM ocean model. The Lagrangian model also includes tides, which are obtained from a standard tidal model customized to the Red Sea, and currents induced by local winds. Both models describe exchanges of radionuclides between water and sediments. A number of simulations were carried out to illustrate capabilities of the models. Additionally, flushing times over the Red Sea were evaluated with the Eulerian model, as another example of model use.

The effectiveness of transport of short-lived halocarbons to the upper troposphere and lower stratosphere remains an important uncertainty in quantifying the supply of ozone-depleting substances to the stratosphere. In early 2014, a major field campaign in Guam in the western Pacific, involving UK and US research aircraft, sampled the tropical troposphere and lower stratosphere. The resulting measurements of CH3I, CHBr3 and CH2Br2 are compared here with calculations from a Lagrangian model. This methodology benefits from an updated convection scheme that improves simulation of the effect of deep convective motions on particle distribution within the tropical troposphere. We find that the observed CH3I, CHBr3 and CH2Br2 mixing ratios in the tropical tropopause layer (TTL) are consistent with those in the boundary layer when the new convection scheme is used to account for convective transport. More specifically, comparisons between modelled estimates and observations of short-lived CH3I indicate that the updated convection scheme is realistic up to the lower TTL but is less good at reproducing the small number of extreme convective events in the upper TTL. This study consolidates our understanding of the transport of short-lived halocarbons to the upper troposphere and lower stratosphere by using improved model calculations to confirm consistency between observations in the boundary layer, observations in the TTL and atmospheric transport processes. Our results support recent estimates of the contribution of short-lived bromocarbons to the stratospheric bromine budget.

WOS:000501415400006; International audience; Terrestrial plants seeds, spores and pollen are often dispersed by wind. Likewise, most eggs and larvae of marine organisms are dispersed by oceanic currents. It was historically believed that the spatial scale at which dispersal occurs was orders of magnitude smaller for plants than for fish. However, recent empirical estimates of seed and larval dispersal suggest that these dispersal scales are more alike than previously thought. The modeling approaches used to simulate aerial and aquatic dispersal are also converging. Similar biophysical models are developed, in which outputs of Eulerian models simulating the main physical forcing mechanism (wind or currents) are used as inputs to Lagrangian models that include biological components (such as seed terminal velocity or larval vertical migration). These biophysical models are then used to simulate trajectories of the biological entities (seeds, larvae) in three dimensions. We reflect on these converging trends by first putting them into an historical perspective, and then by comparing the physical and biological processes represented in marine larva vs. terrestrial seed dispersal models, the data used for the models output corroboration, and the tools available to perform simulations. We conclude that this convergence offers the opportunity to bridge the gap between two scientific communities which are currently largely disconnected. More broadly, we also see our comparison across systems as a useful way to strengthen the links between aquatic and terrestrial ecology by sharing knowledge, methods, tools, and concepts.

In the framework of the Urban Dispersion International Evaluation Exercise (UDINEE) project coordinated by the European Commission’s Joint Research Centre, a case study was conducted of the Joint Urban 2003 (JU2003) experimental campaign in the central area of Oklahoma City, USA. The UDINEE project concerned the cases of puff dispersion of the JU2003 campaign, which are of special interest to scenarios related to security studies, such as explosions of radiological dispersal devices. Starting from the fact that puff-dispersion variability is substantial, especially in complex urban areas, even for puffs released under similar meteorological conditions, a methodology is presented for assessing this variability, which is applied to the dispersion of puffs in two of the intensive operation periods of the JU2003 campaign. Lagrangian and Eulerian dispersion models are applied for the simulations. For the Lagrangian model, variability is assessed by repeating the computations a large number of times. For the Eulerian model, variability is assessed by constructing probability density functions of concentrations on the basis of the dispersion-model results. Peak concentrations, dosages, puff-arrival times and puff durations are considered. Percentiles calculated by the Lagrangian model for all the above quantities and by the Eulerian model for peak concentrations and dosages are compared with the measurements. The results are encouraging since in several cases the measured and computed ranges of values overlap.

The aim of this study is to develop a large-eddy simulation (LES)-coupled Lagrangian snow transport model. This model consists of an LES for turbulent flow fields, and a particle transport simulation model based on Newton's equations of motion. Particles are treated as point masses for turbulent flow fields in this study. The interactions of momentum exchange between a fluid and particles are considered. The particle transport simulation includes three physical sub-processes on the snow surface: aerodynamic entrainment, rebound, and splash. Then, we simulated particle transport within a turbulent boundary layer under the low-wind condition in which saltation intermittently occurs. This simulation was calculated with high frequency and high resolution to capture the fine turbulent structures. The initial stage of saltation mainly related to sweeps, and particles were ejected through the process of aerodynamic entrainment. These ejected particle induced more saltating particles, and the number of saltating particles transported through the processes of splash and rebound increased and became dominant as time proceeds. In such processes of splash and rebound under low-wind conditions, the particle transport might be unaffected by turbulent structures.

We estimate the overall CO2 , CH4 , and CO flux from the South Coast Air Basin using an inversion that couples Total Carbon Column Observing Network (TCCON) and Orbiting Carbon Observatory-2 (OCO-2) observations, with the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model and the Open-source Data Inventory for Anthropogenic CO2 (ODIAC). Using TCCON data we estimate the direct net CO2 flux from the SoCAB to be 104 ± 26 Tg CO2 yr −1 for the study period of July 2013–August 2016. We obtain a slightly higher estimate of 120 ± 30 Tg CO2 yr −1 using OCO-2 data. These CO2 emission estimates are on the low end of previous work. Our net CH4 (360 ± 90 Gg CH4 yr −1 ) flux estimate is in agreement with central values from previous top-down studies going back to 2010 (342–440 Gg CH4 yr −1 ). CO emissions are estimated at 487 ± 122 Gg CO yr −1 , much lower than previous top-down estimates (1440 Gg CO yr −1 ). Given the decreasing emissions of CO, this finding is not unexpected. We perform sensitivity tests to estimate how much errors in the prior, errors in the covariance, different inversion schemes, or a coarser dynamical model influence the emission estimates. Overall, the uncertainty is estimated to be 25 %, with the largest contribution from the dynamical model. Lessons learned here may help in future inversions of satellite data over urban areas.

The 1963 Vajont landslide is a key case in landslide literature, because it was catastrophic and because a lot of accurate data were collected before and after its occurrence. In this paper, the main focus is on the possible heterogeneity of the sliding surface involved by the landslide motion, which is reflected by a heterogeneous distribution of the dynamic basal friction coefficient l. Assuming a given zonation of the sliding surface, our strategy was to apply a 2D Lagrangian model to compute the landslide motion and to find the values of l for each zone, leading to the best agreement between the computed and the observed final deposit. Following some hints from the literature, we have explored heterogeneous configurations composed of up to four different zones, including also the homogeneous case, by means of a 2D numerical model (UBO-BLOCK2) that handles the landslide as a mesh of blocks and runs quickly enough to allow the computation of tens of thousands of simulations in a reasonable computing time. It is found that the four-zone zonation produces the best fit (or the least misfit), which is a strong hint that the gliding surface involved different geotechnical units.

In the present research, the effect of variations of the electron beam voltage on the output power is studied. In order to develop the study, this problem was investigated at different frequencies, which are the products of nonlinear behavior of the traveling wave tube (TWT) in response to the input frequency. Moreover, for a more realistic understanding, the tubes were considered with two linear and nonlinear responses to the input frequency. The TWT output power was calculated in linear and nonlinear modes, at different frequencies using the numerical solution of the mathematical equations of the Lagrangian model. Then, the output power in terms of distance and beam voltage in different frequencies was plotted and compared. The results revealed that the effects of variations of voltage on the output power were more proper in a single-mode TWT in comparison with a multimode one.

A numerical model, previously validated with other radionuclides, was applied to simulate the dispersion of 236U released from European nuclear fuel reprocessing plants in the North Atlantic and Shelf Seas using a published reconstruction of Sellafield and La Hague releases. Model results are in better agreement with observations if the lowest estimation of such releases are used. This implies that approximately 40 kg of 236U has been discharged from Sellafield. It was found that adsorption of 236U on bed sediments of the shallow European Shelf Seas plays an essential role in its dispersion patterns. This contrasts strongly with the more conservative behaviour of 129I in the same area. This has two important implications in the use of 236U as oceanographic tracer; i) special care must be taken in coastal areas, as sediments might act as sinks and sources of 236U; ii) the annual input function of 236U into the Arctic is not directly controlled by the annual discharges from Sellafield and La Hague, since sediments from the Irish, Celtic and North Sea modulate and smooth the signal. Only 52% of the total releases enter into the Arctic Ocean.

The Arctic Ocean has suffered extreme reductions in sea ice in recent decades, and these observed changes suggest implications in terms of moisture transport. The Arctic region is a net sink of moisture in terms of the total hydrological cycle, however, its role as a moisture source for specific regions has not been extensively studied. Our results show that 80% of the moisture supply from the Arctic contributes to precipitation over itself, representing about 8% of the global moisture supply to the Arctic, the remaining 20% is distributed in the surrounding. A reduction in the sea ice extent could make the Arctic Ocean a slightly higher source of moisture to itself or to the surrounding areas. The analysis of the areas affected by Arctic moisture transport is important for establishing those areas vulnerable to change in a framework of a growing sea ice decline. To this end, the Lagrangian model FLEXPART was used in this work to establish the main sinks for the Arctic Ocean, focusing on the moisture transport from this region. The results suggest that most of the moisture loss occurs locally over the Arctic Ocean itself, especially in summer. Some moisture contribution from the Arctic Ocean to continental areas in North America and Eurasia is also noted in autumn and winter especially from Central Arctic, the East Siberian Sea, the Laptev, Kara, Barents, East Greenland and Bering Seas, and the Sea of Okhotsk.

The Fertile Crescent (FC) region comprises the east coast of the Mediterranean Sea and the northern part of the Arabian Peninsula. The FC suffered two severe drought episodes separated by a 7-year period, in 1998–2000 and 2007–2009, which are considered the most severe episodes to hit the region in the last 50 years. A Lagrangian model (FLEXPART) and ERA-Interim data (with a 1° × 1° lat-long resolution) were used to identify for the first time the climatological sources of moisture for the FC and their characteristics. Variability and the source-receptor relationships, concerning their contribution to the precipitation, and the implications regarding the transport of moisture changes over the FC, during the wet season (October-May) from 1980 to 2014 were analysed. The main climatological moisture sources during this period were determined to be the FC itself, the eastern Mediterranean Sea, the Red Sea, the Persian Gulf, the Arabian Sea, the Caspian and Black Seas, and the central and western parts of the Mediterranean Sea. The analysis showed higher anomalous conditions in the moisture transport from some moisture sources during the two outstanding drought episodes. The key feature of the wet seasons during these episodes was a deficit in the moisture losses over the studied area related to the FC itself, the Red and Arabian Seas sources, followed and to a lesser extent by the eastern Mediterranean Sea over the northern part of the FC region. Nevertheless, the moisture supply deficit from the sources was much greater during the 2007–2009 drought event. The SPEI index at large scales (24 months) showed that the 2007–2009 episode was part of longer-term drought conditions that had been developing over the previous months, reinforcing the drought severity given recycling processes attributed to the FC. During the two extreme drought episodes, the mountainous terrain over the northern and eastern FC suffered the highest precipitation deficits, and these areas are, precisely, the most influenced by two of the major moisture sources, namely, the FC and eastern Mediterranean Sea. The decreased moisture contribution from these main sources led to more intense droughts over the region. As a result, both regions should be considered as hotspots to signal severe or extreme droughts in the region.

The Moving-Particle Semi-implicit (MPS) method is a type of meshless Lagrangian calculation technique that uses particles to perform calculations instead of meshes. This method is straightforward and has a high computational efficiency. In this paper, a Lagrangian model for the numerical simulation of fluid-structure interaction problems is proposed. In the proposed method, both the fluid and the structure are described by the MPS. The fluid is fully coupled with the solid that can undergo large structural deformations. In practical engineering, many existing fluid problems involve turbulent flows. The large eddy simulation (LES) method is a major means of studying turbulence. The modified MPS method with the LES method is applied in two-dimensional dam-break problems, which validates the use of the MPS method for solving fluid-structure coupled problems with turbulent flows. By taking the meshless advantage of the MPS method, a preliminary simulation of the plate break problem is carried out, and the simulation results are theoretically verified.

Transport of oil through pipelines is at an all-time high and so is the risk of oil spill accidents. The July 2010 spill of diluted bitumen into the Kalamazoo River was the largest release of heavy crude into an inland waterway in the history of United States. After extensive cleanup and recovery efforts, substantial residual deposits from the oil spill remained in the river system, mainly due to the formation of oil–particle aggregates (OPAs). Understanding the conditions under which OPAs can be suspended, transported and deposited is important for river management. Concerns about OPAs reaching Lake Michigan motivated this work. A three-dimensional Eulerian/Lagrangian model for OPA transport was developed for Morrow Lake in the Kalamazoo River, using specified OPA properties based on laboratory experiments. The three-dimensional model included the Morrow Lake dam operational rules as well as wind effects, which might increase the risk of resuspension and transport of OPA downstream. The usage of the model as a management tool is illustrated; the suitability of the model framework to incorporate the more complex processes of OPA formation transformation is discussed.

In this work the decrease in the number of particles due to decrease in the size of the detection window on particle diffusion is investigated with the use of a numerical model of saltating grains. In order to formulate the problem, the available experimental data of particle diffusion are presented and discussed. Five different detection window sizes are investigated, showing that in both transverse and longitudinal directions the calculated dispersion of the particles noticeably decreases with the decrease in the window size. This highlights the “window” effect on the calculated variance of particle positions. The results indicate that the interpretation of the experimental data may be biased due to the “window” effect leading to potentially false conclusions about the regime of the diffusion of particles.

Describing the effects of wind meandering motions on the dispersion of scalars is a challenging task, since this type of flow represents a physical state characterized by multiple scales. In this study, a Lagrangian stochastic diffusion model is derived to describe scalar transport during the horizontal wind meandering phenomenon that occurs within a planetary boundary layer. The model is derived from the linearization of the Langevin equation, and it employs a heuristic functional form that represents the autocorrelation function of meandering motion. The new solutions, which describe the longitudinal and lateral wind components, were used to simulate tracer experiments that were performed in low-wind speed conditions. The results of the comparison indicate that the new model can effectively reproduce the observed concentrations of the contaminants, and therefore, it can satisfactorily describe enhanced dispersion effects due to the presence of meandering.

Effect of the swirl on the turbulent flow fluctuations is investigated based on a Lagrangian model of a fluid element. Motion of a fluid element in a mean swirling flow is considered. It is shown that turbulence can be suppressed by swirl and that swirl may result in an anisotropy of turbulent fluctuations. The hydrodynamic causes of such effects are studied. A coefficient of elasticity for a turbulent swirling flows is introduced. The results of the present work can be useful for the analysis of turbulence structure in swirling flows.

European eel can be found at the Bay of Biscay after a long migration across the Atlantic. The duration of migration, which takes place at larval stage, is of primary importance to understand eel ecology and, hence, its survival. This duration is still a controversial matter since it can range from 7 months to > 4 years depending on the method to estimate duration. The minimum migration duration estimated from our lagrangian model is similar to the duration obtained from the microstructure of eel otoliths, which is typically on the order of 7–9 months. The lagrangian model showed to be sensitive to different conditions like spatial and time resolution, release depth, release area and initial distribution. In general, migration showed to be faster when decreasing the depth and increasing the resolution of the model. In average, the fastest migration was obtained when only advective horizontal movement was considered. However, faster migration was even obtained in some cases when locally oriented random migration was taken into account.

Magnetic nano drug targeting, through the use of an external magnetic field, is a new technique for the treatment of several diseases, which can potentially avoid the dispersion of drugs in undesired locations of the body. Nevertheless, due to the limitations on the intensity of the magnetic field applied, the hydrodynamic forces can reduce the effectiveness of the procedure. This technique is studied in this paper with the Computational Fluid Dynamics (CFD), focusing on the influence of the magnetic probe position, and the direction of the circulating electric current. A single rectangular coil is used to generate the external magnetic field. A patient-specific geometry of the coeliac trunk is reconstructed from DICOM images, with the use of VMTK. A new solver, coupling the Lagrangian dynamics of the nanoparticles with the Eulerian dynamics of the blood, is implemented in OpenFOAM to perform the simulations. The resistive pressure, the Womersley’s profile for the inlet velocity and the magnetic field of a rectangular coil are implemented in the software as boundary conditions. The results show the influence of the position of the probe, as well as the limitations associated with the rectangular coil configuration.

The occurrence of resonance in an acoustic system as a result of a change of the dispersion of a gas suspension filling a resonator with fixed external excitation parameters was studied. The dynamics of the medium is described by a system of equations of motion of a multi-velocity multi temperature continuum taking into account pulse and energy exchange between the carrier phase and the disperse fractions. Coagulation of different particle fractions is simulated by Smolukhovskii’s Lagrangian model, which takes into account pair collisions. Resonance occurs as a result of the resonance frequency of the system approaching a fixed external excitation frequency as a result of a change in the dispersion of the gas suspension during coagulation initiated by the addition of a small amount of the large particle fraction to the finely dispersed gas suspension. As a result of calculations, an estimate for the time of the change in dispersion of the system and the generation of resonance oscillations were obtained.

Computational efficiency and accuracy of transient analysis for urban water distribution networks (WDN) become progressively important to the design and management of the system. In addition to the improvement of numerical model and computational capacity, which has been widely studied in the literature, efficient and accurate treatment of practical and complex WDN is another potential way to enhance the transient analysis. This paper aims to develop a zonal method for effective decomposition of WDN, which is mainly based on the transient sources and their influence regions in the system, in order to achieve efficient transient analysis. A concept of transient influence zone (TIZ) is firstly proposed and implemented to demonstrate the critical influence region of transient wave propagation in the system under specific design criteria. The obtained TIZ for each transient source is then mapped by introducing appropriate and equivalent boundaries so as to separate the TIZ from the entire WDN. To this end, the efficient Lagrangian model for prior-estimating pressure fluctuation extremes, the pressure fluctuation limitation for mapping TIZ borders and the quasi-reservoir condition for representing border boundaries are applied for characterizing the TIZs. A realistic network is adopted to demonstrate the applicability and accuracy of the proposed method. The application results and analysis indicate that the developed TIZ-based decomposition method provides a considerable efficiency improvement for transient analysis with sufficient modeling accuracy.

Since Lagrangian model coefficients vary with different conditions, it is necessary to calibrate the model to obtain optimal coefficient combination for special oil spill accident. This paper focuses on proposing a new method to calibrate Lagrangian model with time series of Envisat ASAR images. Oil slicks extracted from time series images form a detected trajectory of special oil slick. Lagrangian model is calibrated by minimizing the difference between simulated trajectory and detected trajectory. mean center position distance difference (MCPD) and rotation difference (RD) of Oil slicks' or particles' standard deviational ellipses (SDEs) are calculated as two evaluations. The two parameters are taken to evaluate the performance of Lagrangian transport model with different coefficient combinations. This method is applied to Penglai 19-3 oil spill accident. The simulation result with calibrated model agrees well with related satellite observations. It is suggested the new method is effective to calibrate Lagrangian model.

Pesticides play an important role in providing high crop yields by minimising the risks associated with pests but some of the sprayed product may move beyond the intended target and result in drift. Modelling approaches can help understand the behaviour of spray drift using computer simulations. However, modelling drift from orchard spraying presents particular challenges: (1) the moving spray interacts with the canopy before drifting outside the target area; (2) the vertical wind profile in the orchard is different to neighbouring fields where there is different vegetation; (3) the moving air jet from the air-assistance cannot be ignored because the airspeed of the fan is usually higher than the wind speed.This work presents a three-dimensional (3D) computational fluid dynamics (CFD) model of spray drift from orchard sprayers that considers tree architecture, canopy wind flow and the movement of the sprayer to calculate sedimenting and airborne drift; thus tackling the challenges listed above. The model was validated against drift measurements from an apple orchard with different nozzles arrangements. The model was then used to evaluate the effect of drift reducing nozzles and fan airspeed on drift. The model predicted that drift reducing nozzles reduced the drifting distance by 50%, but increased near-tree ground deposition. This increase in ground deposition can be avoided whilst retaining the reduction in the drifting distance, by using a combination of drift reducing and standard nozzles. A reduced sprayer airflow can further reduce drift. publisher: Elsevier articletitle: Development and validation of a 3D CFD model of drift and its application to air-assisted orchard sprayers journaltitle: Biosystems Engineering articlelink: http://dx.doi.org/10.1016/j.biosystemseng.2016.10.010 content_type: article copyright: © 2016 IAgrE. Published by Elsevier Ltd. All rights reserved. ispartof: Biosystems Engineering vol:154 pages:62-75 status: published

The viruses spread in the air-conditioning room with the droplets produced by talking, coughing, sneezing and other respiratory behavior, which pollute the indoor air and threaten to human health. This paper studies the influence of lateral-supply top-return, upper-supply top-return and bottom-supply upper-return in the transport of coughed droplets by using a Lagrangian model in a conference room, besides no ventilation is considered for comparison. The non-steady-state is used and gravity, drag force and Brownian force of coughed droplets are accounted. The simulation results indicate that the exposed sitting at the middle of conference table are more susceptible to infection for lateral-supply top-return and upper-supply top-return. The exposed sitting near the polluter are more susceptible to infection in bottom-supply upper-return. Bottom-supply upper-return air-flow organization, such as Displacement Ventilation and Underfloor Air Distribution, can control the spread of respiratory diseases effectively and provide people with a healthy and comfortable indoor environment.

In this paper, a review of the Lagrangian stochastic models developed in the last decades for the simulation of the concentration–fluctuation dispersion is presented. The main approaches available in the literature are described and their ability in reproducing the higher order moments of the probability density function is discussed. Then, the Lagrangian approaches for evaluating of the odor annoyance are presented. It is worth to notice that, while Lagrangian stochastic models for mean concentrations are well-known and their ability in correctly reproducing the observation is well assessed, concerning concentration fluctuations the approaches are often new and unknown for most of the scientific community.

ATLAS-1.0 (ATmospheric LAgrangian diSpersion) is a new atmospheric dispersion and sedimentation Lagrangian model tailored to volcanic tephra/ash. The model solves the Advection–Diffusion–Sedimentation equation across multiple scales (from regional to global) and can be driven off-line by different numerical weather prediction models in combination. For example, meteorological data from the mesoscale Weather Research Forecast (WRF) model can be combined with data from the Global Forecast System (GFS) so that ATLAS automatically selects the highest resolution data available in any part of the computational domain. ATLAS can be used in forward mode to forecast ash dispersal from a volcano (or from extended sources) or in backward mode to integrate trajectories backwards in time and constrain unknown source term characteristics. Multiple source terms can be defined, e.g. to simulate several eruption phases with different granulometric characteristics on a single model execution. We validate the implementation of the model using the 2011 Cordón Caulle and the 2015 Calbuco eruptions and compare the results with previous simulations performed with the FALL3D model. The code has been designed from scratch to facilitate future parallelization, inclusion of ash resuspension schemes, and ensemble-based probabilistic forecast assimilating data from satellite retrievals. Fil: Reckziegel, Florencia Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones en Energía no Convencional. Universidad Nacional de Salta. Facultad de Ciencias Exactas. Departamento de Física. Instituto de Investigaciones en Energía no Convencional; Argentina Fil: Folch Duran, Arnau. Barcelona Supercomputing Center; España Fil: Viramonte, Jose German. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones en Energía no Convencional. Universidad Nacional de Salta. Facultad de Ciencias Exactas. Departamento de Física. Instituto de Investigaciones en Energía no Convencional; Argentina

In this study, the moisture sources acting over each sea (Weddell, King Haakon VII, East Antarctic, Amundsen-Bellingshausen, and Ross-Amundsen) of the Southern Ocean during 1980&ndash, 2015 are identified with the FLEXPART Lagrangian model and by using two approaches: backward and forward analyses. Backward analysis provides the moisture sources (positive values of Evaporation minus Precipitation, E &minus, P &gt, 0), while forward analysis identifies the moisture sinks (E &minus, P &lt, 0). The most important moisture sources for the austral seas come from midlatitude storm tracks, reaching a maximum between austral winter and spring. The maximum in moisture sinks, in general, occurs in austral end-summer/autumn. There is a negative correlation (higher with 2-months lagged) between moisture sink and sea ice concentration (SIC), indicating that an increase in the moisture sink can be associated with the decrease in the SIC. This correlation is investigated by focusing on extremes (high and low) of the moisture sink over the Weddell Sea. Periods of high (low) moisture sinks show changes in the atmospheric circulation with a consequent positive (negative) temperature anomaly contributing to decreasing (increasing) the SIC over the Weddell Sea. This study also suggests possible relationships between the positive (negative) phase of the Southern Annular Mode with the increase (decrease) in the moisture that travels from the midlatitude sources to the Weddell Sea.

A single particle Lagrangian Stochastic model has been developed and applied with the purpose of simulating the concentration fluctuations dispersion. This model treats concentration variance as a quantity whose motion is driven by an advection-diffusion process so that it can be studied by a single particle model. A parameterization for both velocity standard deviations and Lagrangian time-scales is required as input to the model. The paper is focused on the estimation of the best parameterization needed to simulate both mean and standard deviation concentrations in a case study. We consider the FFT-07 field experiment. The trials took place at Dugway Proving Ground, UTAH (USA) and consist of a dispersion analysis of a gas emitted from a point-like source in different atmospheric conditions with a continuous emission technique. The very small spatial scales (a few hundred meters) and short duration (about 10 minutes) that characterize the trials make the comparison with model results very challenging, since traditional boundary layer parameterizations fail in correctly reproducing the turbulent field and, as a consequence, the dispersion simulation yields unsatisfactorily results. We vary the coefficients of the turbulence parameterization to match the small-scale turbulence. Furthermore, we show that the parameterization for the variance dissipation time-scale, already tested in neutral conditions, can be used also in stable and unstable conditions and in low-wind speed conditions. The model gives good results as far as mean concentration is concerned and rather satisfactory results for the concentration standard deviations. Comparison between model results and observation is shown through both statistical and graphical analyses.

This study proposes an approach to improve the spatial resolution of ground-level concentrations of PM2.5 that is required to assess health risks associated with exposure to pollutants released during wildfires. We use this approach to analyze the impact on air quality of the wildfire complex consisting of the Atlas, Nuns, Tubbs, Pocket, and Redwood Valley fires in northern California that started on October 8, 2017 and the Camp Fire in northern California that was first reported on November 8, 2018. The PM2.5 concentrations measured in populated areas downwind of these fires were well above the 24-h standard of 35 μ g / m 3 during several days of both fires. To estimate health risks at locations where ground-based monitors did not provide sufficient spatial coverage we first estimate the emissions from the fires by fitting concentration estimates from two models, a Lagrangian model and a segmented plume dispersion model, to corresponding concentrations from ground monitors. We also use a power law model to fit the measured PM2.5 concentrations to the ratio of aerosol optical depth (AOD) to planetary boundary layer measured by the Moderate Resolution Imaging Spectroradiometer (MODIS) carried by NASA's Terra and Aqua satellites. Dispersion model estimates are then combined with estimates from the AOD model to compute ground-level concentrations at a resolution of 1 km. Kriged residuals between estimates from the combined model and measured PM2.5 concentrations are then added to obtain high resolution maps that can be used for exposure studies.

A Lagrangian model which simulates the dispersion of 137Cs in the North Atlantic has been developed. The model includes water/sediment interactions. It has been tested comparing calculated and measured 137Cs concentrations in water and sediments of the European Shelf resulting after the releases from the nuclear fuel reprocessing plants of Sellafield and La Hague. Some additional numerical experiments have been carried out. First, the redissolution of 137Cs from contaminated sediments after the reduction in releases from the reprocessing plants has been studied. This allowed to calculate effective half-lives of 137Cs in several sub-basins. Later, potential leakage of 137Cs from dumped nuclear wastes in several locations of the Atlantic has been investigated. Even in worst-case scenarios, these leakages should not lead to any radiological implications.

In [1] a novel metamaterial has been designed and studied, whose performances include an enhanced toughness in extension: one of the problems to be solved in the further development of the concept involves the study of its deformation induced by loads concentrated on fibers (fiber pull-out test). A continuum model seems particularly unfit for the description of this kind of phenomena. As a consequence, in order to design a campaign of experimental tests we resorted to numerical simulations based on a novel Lagrangian, finite dimensional model for pantographic sheets. The developed code has the robustness features necessary to supply reliable predictions also in presence of very large deformations and, indeed, produces very accurate predictions. The agreement between the presented three-elastic-parameters discrete Lagrangian model and the numerous experimental measurements performed is very accurate. Therefore we are confident that, once we will have improved the model to include damage onset, it will be possible to describe also the rupture and final failure of planar pantographic sheets.

The near-surface transport of exogenous plastics that enter the Bay of Biscay near Cape Ortegal (NW Spain), the main coastal entrance of marine litter into this semi-enclosed sea, were analyzed using a particle tracking model over the period 2009–2018. Four wind drag coefficients were considered to account for the different windages due to the diverse sizes of marine litter. The combined effect of winds and currents results in a higher concentration of floating plastics nearshore favoring beaching. On the other hand, the movement of the smallest plastics (

In this paper, a new method for the simulation of evolving multi-domains problems will be presented. The method is inspired by the front-tracking approaches where only the interfaces between domains are discretized. The presented method maintains the discretization of the interior of the domains using an evolving triangular mesh (valid for a Finite Element (FE) study) and treats the topological events such as the disappearance of domains or the creation of interfaces by means of selective local remeshing operations. Geometric properties are only computed on the interfaces using local spline reconstructions and interfaces are moved using a Lagrangian approach ensuring at all times the validity of the mesh. Accuracy and computational cost of this method will be evaluated in the context of microstructural evolutions, specifically for grain growth mechanism (GG) and it will be compared to a more classical front capturing approach based on a Level-Set (LS) description of grain interfaces which have been proved to be a powerful method for this kind of simulations.

Accumulated pollen sequences are used to infer temporal changes in vegetation composition. Pollen transport and dispersal by winds introduce large biases in the interpretation of pollen records. In order to calibrate the models used to infer past species distributions, human activities or climate, contemporary time series of pollen records are assessed and modelled. The Gaussian plume model assumes that pollen transport takes place in a neutral atmosphere and pollen contribution is even from all directions (isotropy). In this study, we analyse these assumptions with airborne pollen measurements of Weinmannia trichosperma, a forest tree which grows mainly on the western slopes of the Andes, along with other characteristic species of the steppe which develops in eastern Patagonia. Instead of the Gaussian plume mixing model that is usually employed in the theory of pollen analysis, we apply a full 3D Lagrangian dispersion model, which allows calculation of potential source distributions (footprint) from modelled backward trajectories of airborne pollen observations. Results show that neutral atmospheric conditions are properly assumed for the region. The footprint calculated from the modelled trajectories of a five-year record is consistent with the location of pollen sources but the footprint shape showed that pollen contribution is uneven due to the influence of transient weather systems. Fil: Perez, Claudio Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina Fil: Bianchi, Maria Martha. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Secretaría de Cultura de la Nación. Dirección Nacional de Cultura y Museos. Instituto Nacional de Antropología y Pensamiento Latinoamericano; Argentina Fil: Gassmann, María Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina Fil: Tonti, Natalia Edith. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina Fil: Pisso, Ignacio. Norwegian Institute for Air Research; Noruega

In the most recent decades, central Europe and the Danube River Basin area have been affected by an increase in the frequency and intensity of extreme daily rainfall, which has resulted in the more frequent occurrence of significant flood events. This study characterised the link between moisture from the Mediterranean Sea and extreme precipitation events, with varying lengths that were recorded over the Danube River basin between 1981 and 2015, and ranked the events with respect to the different time scales. The contribution of the Mediterranean Sea to the detected extreme precipitation events was then estimated using the Lagrangian FLEXPART dispersion model. Experiments were modelled in its forward mode, and particles leaving the Mediterranean Sea were tracked for a period of time determined with respect to the length of the extreme event. The top 100 extreme events in the ranking with durations of 1, 3, 5, 7, and 10 days were analysed, and it was revealed that most of these events occurred in the winter. For extreme precipitation, positive anomalies of moisture support from the Mediterranean were found to be in the order of 80% or more, but this support reached 100% in summer and spring. The results show that extreme precipitation events with longer durations are more influenced by the extreme Mediterranean anomalous moisture supply than those with shorter lengths. However, it is during shorter events when the Mediterranean Sea contributes higher amounts of moisture compared with its climatological mean values, for longer events, this contribution decreases progressively (but still doubles the climatological moisture contribution from the Mediterranean Sea). Finally, this analysis provides evidence that the optimum time period for accumulated moisture to be modelled by the Lagrangian model is that for which the extreme event is estimated. In future studies, this fine characterisation could assist in modelling moisture contributions from sources in relation to individual extreme events.

We estimate the overall CO 2 , CH 4 , and CO flux from the South Coast Air Basin using an inversion that couples Total Carbon Column Observing Network (TCCON) and Orbiting Carbon Observatory-2 (OCO-2) observations, with the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model, and the Open-source Data Inventory for Anthropogenic CO 2 (ODIAC). Using TCCON data we estimate the direct net CO 2 flux from the SoCAB to be 139 ± 35 Tg CO 2 yr −1 for the study period of July 2013–August 2016. We obtain a slightly lower estimate of 118 ± 29 Tg CO 2 yr −1 using OCO-2 data. These CO 2 emission estimates are in general agreement with previous work. Our net CH 4 (325 ± 81 Gg CH 4 yr −1 ) flux estimate is slightly lower than central values from previous top-down studies going back to 2010 (342–440 Gg CH 4 yr −1 ). CO emissions are estimated at 555 ± 136 Gg CO yr −1 , much lower than previous top-down estimates (1440 Gg CO yr −1 ). Given the decreasing emissions of CO, this finding is not unexpected. We perform sensitivity tests to estimate how much errors in the prior, errors in the covariance, different inversions schemes or a coarser dynamical model influence the emission estimates. Overall, the uncertainty is estimated to be 25 %, with the largest contribution from the dynamical model. The methods described are scalable and can be used to estimate direct net CO 2 fluxes from other urban regions.

Methane is an important greenhouse gas due to its high warming potential. While quantifying anthropogenic methane emissions is important for evaluation measures applied for climate change mitigation, large emission uncertainties still exist for many source categories. To evaluate anthropogenic methane emission inventory in various regions over the globe, we extract emission signatures from column-average methane observations (XCH4) by GOSAT (Greenhouse gases Observing SATellite) satellite using high-resolution atmospheric transport model simulations. XCH4 abundance due to anthropogenic emissions is estimated as the difference between polluted observations from surrounding cleaner observations. Here, reduction of observation error, which is large compared to local abundance, is achieved by binning the observations over large region according to model-simulated enhancements. We found that the local enhancements observed by GOSAT scale linearly with inventory based simulations of XCH4 for the globe, East Asia and North America. Weighted linear regression of observation derived and inventory-based XCH4 anomalies was carried out to find a scale factor by which the inventory agrees with the observations. Over East Asia, the observed enhancements are 30% lower than suggested by emission inventory, implying a potential overestimation in the inventory. On the contrary, in North America, the observations are approximately 28% higher than model predictions, indicating an underestimation in emission inventory. Our results concur with several recent studies using other analysis methodologies, and thus confirm that satellite observations provide an additional tool for bottom-up emission inventory verification.

First we present two classical models of Branched Transport: the Lagrangian model introduced by Bernot, Caselles, Morel, Maddalena, Solimini, and the Eulerian model introduced by Xia. An emphasis is put on the Lagrangian model, for which we give a complete proof of existence of minimizers in a –hopefully– simplified manner. We also treat in detail some σ-finiteness and rectifiability issues to yield rigorously the energy formula connecting the irrigation cost Iα to the Gilbert Energy Eα. Our main purpose is to use this energy formula and exploit a Smirnov decomposition of vector flows, which was proved via the Dacorogna-Moser approach by Santambrogio, to establish the equivalence between the Lagrangian and Eulerian models.

Norway spruce ( Picea abies ), the most representative forest species in central and northern Europe, has previously been described as a monoterpene emitter. However, past studies have shown variable emission rates. In order to understand emissions at the ecosystem scale, a technique utilizing proton-transfer-reaction-time-of-flight (PTR-TOF) mass spectrometry coupled with eddy covariance was applied to determine fluxes of volatile organic compounds and CO 2 above a mountainous Norway spruce forest in the Czech Republic during an intensive field campaign in summer. In addition, an Inverse Lagrangian Transport Model was applied to derive fluxes of various monoterpenes using concentrations measured along a vertical canopy profile by wet effluent diffusion denuder. The Model of Emissions of Gases and Aerosols from Nature (MEGAN) was applied using basal emission factors for sun and shade shoots to predict diurnal fluxes and annual monoterpene emission sums for 5 years. The forest showed itself to be a monoterpene emitter up to 2.03 nmol m −2 s −1 . Isoprene and 2-methyl-3-buten-2-ol (MBO) reached maximum levels during central hours of the day of 1.6 nmol m −2 s −1 , whereas daily average maximum fluxes were 1.29 nmol m −2 s −1 and 0.77 nmol m −2 s −1 for monoterpenes and sum of isoprene and MBO, respectively. The relationship between monoterpene and CO 2 fluxes revealed that as much as 47% of variance in MT emission is predictable from the actual gross primary production of a spruce ecosystem. Modelled MT fluxes agreed with the measured fluxes in terms of diurnal pattern, particularly when basal emission factors 2.72 nmol m −2 s −1 and 0.55 nmol m −2 s −1 for sun and shade shoots, respectively, were used. Nevertheless, strong seasonal variability in MT emission was observed. Our results contribute to better understanding emissions of biogenic volatile organic compounds in central Europe.

A worldwide study is presented to understand the role of major global moisture source regions in the occurrence of extreme monthly precipitation over the continents. The Lagrangian model FLEXPART v9.0 was used to analyse the moisture transport for precipitation, and the extreme precipitation was calculated for each grid point (at 0.25°) using the Multi-Source Weighted-Ensemble Precipitation (MSWEP) monthly precipitation dataset. Although the eventual aim of this work is to show the link between the contributions from the sources to their sinks during months of extreme rainfall, we provide, for the first time, much-needed information on these contributions at a monthly scale – previously this information was only available at an annual scale. We also provide maps showing global monthly moisture sources, together with the identification of the peak precipitation month (PPM) and of the preferred moisture source for precipitation in that month.

The GSOM (Generic second order modelling) family of traffic flow models combines the LWR model with dynamics of driver-specific attributes and can be expressed as a system of conservation laws. The object of the paper is to show that a proper Lagrangian formulation of the GSOM model can be recast as a Hamilton-Jacobi equation, the solution of which can be expressed as the value function of an optimal control problem. This value function is interpreted as the position of vehicles, and the optimal trajectories of the optimal control formulation can be identified with the characteristics. Further the paper analyzes the initial and boundary conditions, proposes a generalization of the inf-morphism and the Lax-Hopf formulas to the GSOM model, and considers numerical aspects.