Dust Trajectories Research Articles

A case study on the dust storm that occurred on March 13–18, 2022, over the Algerian Sahara, using satellite remote sensing

This study investigates the dynamics of a significant dust storm that occurred in Algeria in March 2022, employing data derived from the Sentinel-5P and CALIPSO satellite instruments. We examine the Aerosol Absorbing Index (AAI) to detect n absorbing aerosols, with a focus on desert dust, and analyze the attenuation coefficient. Additionally, we employ the HYSPLIT trajectory analyze to study dust transport and MERRA-2 to examine wind patterns wind. The key findings unveil a detailed trajectory of a prominent dust storm in Algeria in March 2022. The Aerosol Absorbing Index (AAI) effectively identifies absorbing aerosols, particularly desert dust, through thorough analyses of dust trajectory and wind patterns; augmenting these findings, CALIPSO satellite data has provided a detailed vertical profile of aerosols within the dust plume, emphasizing spatial and altitudinal extents. This research significantly contributes to advancing scientific discussions on atmospheric dynamics in arid regions and enhances our understanding and forecasting capabilities related to Saharan dust storm initiation and trajectory.

Inner dusty regions of protoplanetary discs – III. The role of non-radial radiation pressure in dust dynamics

ABSTRACT We explore the dynamical behaviour of dust particles that populate the surface of inner optically thick protoplanetary discs. This is a disc region with the hottest dust and is of a great importance for planet formation and dust evolution, but we still struggle to understand all the forces that shape this environment. In our approach, we combine results from two separate numerical studies, one is the wind velocity and density distributions obtained from magnetohydrodynamical simulations of accretion discs, and the other is a high-resolution multigrain dust radiation transfer. In our previous paper in the series, we described the methodology for utilizing these results as an environmental input for the integration of dust trajectories driven by gravity, gas drag, and radiation pressure. Now we have two improvements, we incorporate time changes in the wind density and velocity, and we implement the non-radial radiation pressure force. We applied our analysis on the Herbig Ae and T Tau stars. We confirm that the radiation pressure force can lead to dust outflow, especially in the case of more luminous stars. Additionally, it opposes dust accretion at the inner disc edge and reduces dust settling. These effects are enhanced by the disc wind, especially in the zone where the stellar and the disc magnetic fields meet. Our results suggest that dust grains can stay in the hottest disc region for an extended period and then end up ejected into the outer disc regions.

Reduction of dust radial drift by turbulence in protoplanetary disks

Reduction of dust radial drift by turbulence in protoplanetary disks

Electrostatic Dust Analyzer for Dust Transport Measurements on the Lunar Surface

Lunar dust charging and transport is a more than five-decade-old problem. A high-fidelity and flight-qualified Electrostatic Dust Analyzer (EDA) has been developed to measure the charge, velocity, mass (size), and flux of electrostatically lofted dust particles on the lunar surface. Recent laboratory findings have greatly advanced our fundamental understanding of the dust-charging and -lofting mechanisms, providing critical constraints to the design of the EDA instrument. EDA consists of two identical dust trajectory sensor (DTS) units on both ends of the instrument with a deflection field electrode (DFE) unit lying in between. When a dust particle enters the instrument, charge signals induced on four arrays of wire electrodes in the two DTS units determine the total charge of the dust particle and its trajectory passing through the instrument from which the dust velocity vector is measured. The mass (size) is derived from the deflection of the dust trajectory by the DFE. A dust campaign was performed to characterize the instrument’s performance. The results meet or exceed the requirements. EDA has achieved high Technology Readiness Level 6. EDA measurements are important for assessing the dust environment on the lunar surface and its subsequent impact on crew safety and the operation of exploration systems. Additionally, EDA measurements are expected to have important implications for the surface evolution of all airless bodies, including the Moon and asteroids, in the solar system.

Effective Reaction Temperatures of Irreversible Dust Chemical Reactions in a Protoplanetary Disk

Dust particles in protoplanetary disks experience various chemical reactions under different physicochemical conditions through their accretion and diffusion, which results in the radial chemical gradient of dust. We performed three-dimensional Monte Carlo simulations to evaluate the dust trajectories and the progress of fictitious irreversible reactions, of which kinetics is expressed by the Johnson–Mehl–Avrami equation. The distribution of the highest temperature that each particle experiences before the degree of reaction exceeds a certain level shows the lognormal distribution, and its mode temperature was used as the effective reaction temperature. Semi-analytical prediction formulas of the effective reaction temperature and its dispersion were derived by comparing a reaction timescale with a diffusive transport timescale of dust as a function of the reaction parameters and the disk parameters. The formulas reproduce the numerical results of the effective reaction temperatures and their dispersions within 5.5% and 24%, respectively, in a wide temperature range (200–1400 K). We applied the formulas for the crystallization of amorphous silicate dust and its oxygen isotope exchange with the H2O vapor based on the experimentally determined kinetics. For submicron-sized amorphous forsterite dust, the predicted effective reaction temperature for the oxygen isotope exchange was lower than that of crystallization without overlap even considering their dispersions. This suggests that the amorphous silicate dust in the protosolar disk could exchange their oxygen isotopes efficiently with the 16O-poor H2O vapor, resulting in the distinct oxygen isotope compositions from the Sun.

Numerical simulation of dual-layer granular bed filtration based on particle collision rebound effect

This article established a dual-layer granular bed filtration model based on the dust collision rebound effect and investigated the influence of dust properties and filtration air velocity on the collision rebound effect and grade efficiencies of the filter layers. The results indicated that the characteristics of dust particle size, density, and effective Young's modulus had a significant impact on the critical adhesion velocity and collision rebound effect. Large dust particle size, density, and small effective Young's modulus resulted in a larger collision rebound effect. The collision rebound effect led to a decrease in grade efficiencies of each filter layer and the dual-layer granular bed with an increase in filtration velocity. To reveal the impact of the collision rebound effect on the movement of dust in the filter material layer, the trajectory and velocity changes of dust in the granule layer were simulated and calculated. The results show that the collision rebound effect caused the dust to repeatedly collide and rebound within the granular bed, penetrating deeper into the granular bed and increasing dust escape.

Study on the influence pattern and efficiency enhanced mechanism of acoustic–chemical spray dust reduction

To study the influence pattern and efficiency enhanced mechanism of acoustic–chemical spray method on dust reduction, a self-developed acoustic excitation test platform, viscosity test, surface tension experiment and sinking experiments were used to investigate the chemical spray properties and the wetting behavior of coal dust excited by acoustic waves. The self-developed acoustic–chemical spray dust reduction simulation platform was used to study the influence of acoustic waves on coal dust reduction effect and its efficiency enhanced mechanism. The results showed that the surface tension and viscosity of the chemical spray solution fluctuated between 0.4 mN/m and 0.4 mPa·s along with the variations in acoustic wave frequency and sound pressure level (SPL), thereby confirming that acoustic waves had on effected on chemical spray solution properties. However, the wetting time of the chemical spray solution on coal dust increased by 33.64 % at an acoustic frequency (f) of 1300 Hz and SPL of 120 dB because of the liquid interface vibrations caused by acoustic waves. With an increasing of acoustic frequency, the dust reduction efficiency demonstrated a parabolic trend and reached its maximum value at f = 1300 Hz. The dust reduction efficiency also increased exponentially along with increasing SPL. Acoustic waves not only increased the collision frequency between particles and droplets by changing the trajectory of dust but also accelerated the wetting and agglomeration effect of chemical spray reagents on coal dust by causing vibrations at the gas–liquid interface, thereby enhancing the dust reduction efficiency. Compared to the dust reduction efficiency of chemical spray technology, the total dust reduction efficiency was increased by 8.53 %, and the respirable dust reduction efficiency was increased by 21.93 %. The effect of acoustic waves on the respirable dust reduction efficiency was more significant than that on total dust.

Comparison of the Eulerian and Lagrangian Approaches to Studying the Peculiarities of the Interstellar Dust Distribution in the Heliosphere in the Framework of the Cold Gas Model

Interstellar dust grains penetrate into the heliosphere (region in which the solar wind propagates) due to the relative motion of the Sun and the Local Interstellar Medium (LISM). Inside the heliosphere, the motion of dust particles is mainly governed by the electromagnetic force determined by the heliospheric magnetic field. Under the action of this force, the trajectories of dust grains experience intersections with each other and self-intersections. As a result, dust density accumulation regions appear. These regions are of a great interest in the context of theoretical studying and planning of upcoming space missions. The main aim of the present study is to model the interstellar dust distribution in the heliosphere and investigate the peculiarities of the number density distribution. To describe the dusty component, the cold gas model is used, while to compute the interstellar dust distribution two approaches are considered, namely, the Eulerian and Lagrangian approaches. For solving the continuity equation in the Lagrangian coordinates, the full Lagrangian method or the Osiptsov method is used. As a result, all the peculiarities of the dust distribution are investigated and it is found that they are located on caustics, i.e., the envelopes of interstellar dust trajectories. Besides it, the regular regions of overdensity (without singularities in the number density) are discovered. It is shown that the dust component accumulation regions are located in a small neighborhood of the heliospheric current sheet, at which the magnetic field changes its polarity, and in the tail of the heliosphere. The effectiveness of the Osiptsov method of solving the continuity equation is compared with the widely used Monte Carlo method (Eulerian approach). It is shown that Monte Carlo method requires extremely high resolution of computational grid to reach the level of accuracy comparable with the Osiptsov method.

Comparison of the Eulerian and Lagrangian Approaches to Studying the Peculiarities of the Interstellar Dust Distribution in the Heliosphere in the Framework of the Cold Gas Model

Interstellar dust grains penetrate into the heliosphere (region in which the solar wind propagates) due to the relative motion of the Sun and the Local Interstellar Medium (LISM). Inside the heliosphere, the motion of dust particles is mainly governed by the electromagnetic force determined by the heliospheric magnetic field. Under the action of this force, the trajectories of dust grains experience intersections with each other and self-intersections. As a result, dust density accumulation regions appear. These regions are of a great interest in the context of theoretical studying and planning of upcoming space missions. The main aim of the present study is to model the interstellar dust distribution in the heliosphere and investigate the peculiarities of the number density distribution. To describe the dusty component, the cold gas model is used, while to compute the interstellar dust distribution two approaches are considered, namely, the Eulerian and Lagrangian approaches. For solving the continuity equation in the Lagrangian coordinates, the full Lagrangian method or the Osiptsov method is used. As a result, all the peculiarities of the dust distribution are investigated and it is found that they are located on caustics, i.e., the envelopes of interstellar dust trajectories. Besides it, the regular regions of overdensity (without singularities in the number density) are discovered. It is shown that the dust component accumulation regions are located in a small neighborhood of the heliospheric current sheet, at which the magnetic field changes its polarity, and in the tail of the heliosphere. The effectiveness of the Osiptsov method of solving the continuity equation is compared with the widely used Monte Carlo method (Eulerian approach). It is shown that Monte Carlo method requires extremely high resolution of computational grid to reach the level of accuracy comparable with the Osiptsov method.

КОМПЛЕКСНАЯ ОЦЕНКА ЗАПЫЛЕННОСТИ ПРИЗЕМНОГО СЛОЯ АТМОСФЕРЫ В ГРАНИЦАХ ГОРНОГО ОТВОДА УГОЛЬНОГО РАЗРЕЗА

The article describes the results of gravimetric and electrical methods for analyzing the dust content of the atmosphere of a coal mine before and after a mass explosion. The relevance of this study is due to the need to uncover the mechanisms of influence of the meteorological parameters of the region, as well as the microclimate of the coal mine on the formation and further spread of the dust and gas cloud within the boundaries of the section and beyond. The influence of climatic conditions and microclimate of the section on the trajectory of the dust and gas cloud propagation within the quarry was determined by determining the mass gain of samplers located in a certain sector, as well as by conducting a priori and a posteriori estimates of the dust content of the surface layer of the atmosphere. The results of the study can be used to establish new empirical patterns describing the influence of meteorological parameters on the trajectory of a dust and gas cloud in the atmosphere, as well as to develop new empirical patterns describing the influence of meteorological parameters on the trajectory of dust and gas cloud propagation in the atmosphere, as well as for the development of new methods of cloud monitoring and control.

Implementation of dust particles in three-dimensional magnetohydrodynamics simulation: dust dynamics in a collapsing cloud core

ABSTRACT The aim of this study is to examine dust dynamics on a large scale and investigate the coupling of dust with gas fluid in the star formation process. We propose a method for calculating the dust trajectory in a gravitationally collapsing cloud, where the dust grains are treated as Lagrangian particles and are assumed to be neutral. We perform the dust trajectory calculations in combination with non-ideal magnetohydrodynamics simulation. Our simulation shows that dust particles with a size of $\le 10\, {\rm \mu m}$ are coupled with gas in a star-forming cloud core. We investigate the time evolution of the dust-to-gas mass ratio and the Stokes number, which is defined as the stopping time normalized by the freefall time-scale, and show that large dust grains ($\gtrsim 100\, {\rm \mu m}$) have a large Stokes number (close to unity) and tend to concentrate in the central region (i.e. protostar and rotationally supported disc) faster than do small grains ($\lesssim 10\, {\rm \mu m}$). Thus, large grains significantly increase the dust-to-gas mass ratio around and inside the disc. We also confirm that the dust trajectory calculations, which trace the physical quantities of each dust particle, reproduce previously reported results obtained using the Eulerian approach.

Dust entrainment in photoevaporative winds: Synthetic observations of transition disks

Context. X-ray- and extreme-ultraviolet- (XEUV-) driven photoevaporative winds acting on protoplanetary disks around young T Tauri stars may strongly impact disk evolution, affecting both gas and dust distributions. Small dust grains in the disk are entrained in the outflow and may produce a detectable signal. In this work, we investigate the possibility of detecting dusty outflows from transition disks with an inner cavity. Aims. We compute dust densities for the wind regions of XEUV-irradiated transition disks and determine whether they can be observed at wavelengths 0.7 ≲ λobs [μm] ≲ 1.8 with current instrumentation. Methods. We simulated dust trajectories on top of 2D hydrodynamical gas models of two transition disks with inner holes of 20 and 30 AU, irradiated by both X-ray and EUV spectra from a central T Tauri star. The trajectories and two different settling prescriptions for the dust distribution in the underlying disk were used to calculate wind density maps for individual grain sizes. Finally, the resulting dust densities were converted to synthetic observations in scattered and polarised light. Results. For an XEUV-driven outflow around a M* = 0.7 M⊙ T Tauri star with LX = 2 × 1030 erg s-1, we find dust mass-loss rates Ṁdust ≲ 2.0 × 10−3 Ṁgas, and if we invoke vertical settling, the outflow is quite collimated. The synthesised images exhibit a distinct chimney-like structure. The relative intensity of the chimneys is low, but their detection may still be feasible with current instrumentation under optimal conditions. Conclusions. Our results motivate observational campaigns aimed at the detection of dusty photoevaporative winds in transition disks using JWST NIRCam and SPHERE IRDIS.

Dust entrainment in photoevaporative winds: Densities and imaging

Context. X-ray- and extreme-ultraviolet- (together: XEUV-) driven photoevaporative winds acting on protoplanetary disks around young T-Tauri stars may crucially impact disk evolution, affecting both gas and dust distributions. Aims. We constrain the dust densities in a typical XEUV-driven outflow, and determine whether these winds can be observed at μm-wavelengths. Methods. We used dust trajectories modelled atop a 2D hydrodynamical gas model of a protoplanetary disk irradiated by a central T-Tauri star. With these and two different prescriptions for the dust distribution in the underlying disk, we constructed wind density maps for individual grain sizes. We used the dust density distributions obtained to synthesise observations in scattered and polarised light. Results. For an XEUV-driven outflow around a M* = 0.7 M⊙ T-Tauri star with LX = 2 × 1030 erg s−1, we find a dust mass-loss rate Ṁdust ≲ 4.1 × 10−11 M⊙ yr−1 for an optimistic estimate of dust densities in the wind (compared to Ṁgas ≈ 3.7 × 10−8 M⊙ yr−1). The synthesised scattered-light images suggest a distinct chimney structure emerging at intensities I∕Imax < 10−4.5 (10−3.5) at λobs = 1.6 (0.4) μm, while the features in the polarised-light images are even fainter. Observations synthesised from our model do not exhibit clear features for SPHERE IRDIS, but show a faint wind signature for JWST NIRCam under optimal conditions. Conclusions. Unambiguous detections of photoevaporative XEUV winds launched from primordial disks are at least challenging with current instrumentation; this provides a possible explanation as to why disk winds are not routinely detected in scattered or polarised light. Our calculations show that disk scale heights retrieved from scattered-light observations should be only marginally affected by the presence of an XEUV wind.

Dust observations from Parker Solar Probe: dust ejection from the inner Solar System

Context. The FIELDS instrument onboard Parker Solar Probe (PSP) observes dust impacts on the spacecraft. The derived dust flux rates suggest that the particles originate from the vicinities of the Sun and are ejected by radiation pressure. Radiation pressure typically ejects particles of several 100 nm and smaller, which are also affected by the electromagnetic force. Aims. We aim to understand the influence of the electromagnetic force on the dust trajectories and to predict the dust fluxes along the orbit of PSP, within 1 AU and near Earth. Methods. We study the trajectories of dust particles influenced by gravity, radiation pressure, and the electromagnetic force assuming that pitch-angle scattering can be neglected (scatter-free approximation). We estimate the dust fluxes along the second orbit of PSP and in the vicinity of the Earth based on average dust velocities derived from the trajectory calculations and dust production rates derived from a fragmentation model. Results. The calculated cumulative flux of dust particles larger than 100 nm is of the same order (within a factor of ~2) as implied by PSP observations. In this size interval, the dynamics of most particles is dominated by the radiation pressure force. The Lorentz force becomes more important for smaller particles and fluxes can vary with magnetic field conditions. The calculated flux of the 30 to 75 nm particles at the PSP is negligible for most of the second orbit, except for an isolated peak at the perihelion. The 30–75 nm particles that were created inwards from 0.16 AU from the Sun are in trapped orbits if the radiation pressure force is weaker than gravity, which is the case for dust from asteroids and for cometary dust that was altered in space. Conclusions. The inner Solar System is the most likely source of dust smaller than 100 nm that enters Earth’s atmosphere and our results suggest the flux is time-variable.

Modeled Atmospheric Optical and Thermodynamic Responses to an Exceptional Trans‐Atlantic Dust Outbreak

AbstractLong‐range aerosol transport is an important physical mechanism for ecological, biological, and hydrological elements of the earth system. Regarding the latter, regional climate models have no way of assimilating future aerosol concentrations, so dust aerosol emissions must be parameterized using local landscape and meteorological conditions. The purpose of this study is to evaluate the accuracy of different dust emission settings within the Weather Research and Forecasting model coupled with chemistry (WRF‐Chem) to facilitate future dynamical downscaling work. This study performs nine WRF‐Chem hindcasts, each utilizing a different dust emission configuration, from 1 March to 31 May 2015, coinciding with a Saharan air layer (SAL) dust outbreak during the 2015 Caribbean drought. WRF‐Chem aerosol optical depth (AOD) and Gálvez‐Davison Index (GDI), a convective forecasting parameter, are validated against analogous MODIS, AERONET, and ERA5 products. In aggregate, the GOCART dust emission scheme with Air Force Weather Agency modifications (GOCART‐AFWA) achieved the best balance between AOD and GDI accuracy when employing the default tuning constant (1.00). As the schemes emitted dust more aggressively, WRF‐Chem produced warming at 500 hPa, reducing GDI over the central and eastern Atlantic near the modeled dust trajectory. Though AOD was generally too low over the southwest Atlantic, the eastern Caribbean occupies a transition zone between negative and positive AOD biases where this field was hindcast with relative accuracy. Meanwhile, areas with positive AOD biases were associated with negative GDI biases (and vice versa) indicating the covariability between SAL dust loadings and thermodynamic conditions in the tropical north Atlantic.

CFD simulation of multi-phase and multi-component diffusion of air-dust-gas in a fully mechanized mining face.

To explore the rule of airflow-dust-gas dispersion and interaction in a fully mechanized mining face, the airflow current vector, the dust trajectory, and the gas spatial distribution were numerically simulated by Fluent. The results show that under the influence of airflow, respiratory dust diffuses to the leeward side of each dust-producing point and footway space and forms a high-concentration (peak concentration 2000mg/m3) dust mass at 2m on the leeward side of the advancing support. Gas tends to accumulate near the coal cutter drum, the roof, and the return air corner of the mining face, and the peak concentration exceeds the lower limit of explosion. Near the rear drum of the coal cutter and at the advancing support, considering that the gas and coal dust concentrations are both high and dust and gas can reduce each other's explosion limit, serious gas and coal dust explosions are extremely likely to occur in the presence of a fire source, which may result in serious consequences. Therefore, the two areas can be regarded as key areas of gas and coal dust explosion prevention and control.

Influence of lunar eclipse of 15 April 2014 on the intrinsic background current noises in fission chamber

The sun-grazing comet C/2011 W3 (Lovejoy) showed a distorted, unconventional tail morphology near its perihelion (1.2Rs). Based on the “Solar Corona and Inner Heliosphere” modeling result of the magnetic field and plasma dynamics in the solar corona, we use the Runge-Kutta method to simulate the moving trajectory of charged dust and ion particles released at different positions from the C/2011 W3 orbit. We find that the dust particles near the sun, which are subject to a strong magnetic Lorentz force, travel differently from their counterparts distant from the sun, where the latter are mainly affected by the solar gravitational force and radiation pressure. According to the simulation results, we propose that the magnetic mirror effect can rebound the charged dust particles back away from the sun and be regarded as one crucial cause of the dust-free zone formation. We find that ions mainly move along magnetic field lines at an acute angle to the comet's direction of motion. The cometary ions' movement direction was determined by the comet's velocity and the coronal magnetic field, which are responsible for the C/2011 W3’s unique comet tail shape near perihelion. Additionally, the ion particles also experience perpendicular drift motion, mainly dominated by the electric field drift, which is similar to and can be used to approximate the solar wind's transverse velocity at its source region.

Inner dusty regions of protoplanetary discs – II. Dust dynamics driven by radiation pressure and disc winds

ABSTRACT We explore dust flow in the hottest parts of protoplanetary discs using the forces of gravity, gas drag, and radiation pressure. Our main focus is on the optically thin regions of dusty disc, where the dust is exposed to the most extreme heating conditions and dynamical perturbations: the surface of optically thick disc and the inner dust sublimation zone. We utilize results from two numerically strenuous fields of research. The first is the quasi-stationary solutions on gas velocity and density distributions from mangetohydrodynamical (MHD) simulations of accretion discs. This is critical for implementing a more realistic gas drag impact on dust movements. The second is the optical depth structure from a high-resolution dust radiation transfer. This step is critical for a better understanding of dust distribution within the disc. We describe a numerical method that incorporates these solutions into the dust dynamics equations. We use this to integrate dust trajectories under different disc wind models and show how grains end up trapped in flows that range from simple accretion on to the star to outflows into outer disc regions. We demonstrate how the radiation pressure force plays one of the key roles in this process and cannot be ignored. It erodes the dusty disc surface, reduces its height, resists dust accretion on to the star, and helps the disc wind in pushing grains outwards. The changes in grain size and porosity significantly affect the results, with smaller and porous grains being influenced more strongly by the disc wind and radiation pressure.

Population exposure to particulate-matter and related mortality due to the Portuguese wildfires in October 2017 driven by storm Ophelia

In October 2017, hundreds of wildfires ravaged the forests of the north and centre of Portugal. The fires were fanned by strong winds as tropical storm Ophelia swept the Iberian coast, dragging up smoke (together with Saharan dust from north-western Africa) into higher western European latitudes. Here we analyse the long-range transport of particulate matter (PM10) and study associations between PM10 and short-term mortality in the Portuguese population exposed to PM10 due to the October 2017 wildfires, the worst fire sequence in the country over the last decades. We analysed space- and ground-level observations to track the smoke plume and dust trajectory over Portugal and Europe, and to access PM10 concentrations during the wildfires. The effects of PM10 on mortality were evaluated using satellite data for exposure and Poisson regression models. The smoke plume covered most western European countries (including Spain, France, Belgium and the Netherlands), and reached the United Kingdom, where the population was exposed in average to an additional PM10 level of 11.7 µg/m3 during seven smoky days (three with dust) in relation to the reference days (days without smoke or dust), revealing the impact of the wildfires on distant populations. In Portugal, the population was exposed in average to additional PM10 levels that varied from 16.2 to 120.6 µg/m3 in smoky days with dust and from 6.1 to 20.9 µg/m3 in dust-free smoky days. Results suggest that PM10 had a significant effect on the same day natural and cardiorespiratory mortalities during the month of October 2017. For every additional 10 µg/m3 of PM10, there was a 0.89% (95% confidence interval, CI, 0–1.77%) increase in the number of natural deaths and a 2.34% (95% CI, 0.99–3.66%) increase in the number of cardiorespiratory-related deaths. With rising temperatures and a higher frequency of storms due to climate change, PM from Iberian wildfires together with NW African dust will tend to be more often transported into Northern European countries, which may carry health threats to areas far from the ignition sites.

Identification and quantitative analysis of dust trajectories in the Hexi Corridor

Dust storms in Northwest China are a major component of global dust storms and it is important to be able to identify and quantitatively analyze their dust trajectories. In this study, the dust events, sources, and transport paths in the Hexi Corridor were identified using ground-measured PM10 data, Navy Aerosol Analysis and Prediction System (NAAPS) data, the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data. Based on these data, the dust trajectories were then screened. Dust events from five cities in the Hexi region were determined for 2015–2018. Next, five main areas affecting the Hexi region were defined; which included the Gobi region between Xinjiang and Mongolia (XG), Taklimakan Desert (TD), Kumtag Desert (KD), Qaidam Basin (QB), and Badain Jaran and Tengger Deserts (BJTD). We quantified the contributions of the dust trajectories for these five main areas and determined that the major areas that affect the Hexi region are the BJTD and KD, which are located close to the study area. The contribution of the dust trajectories in XG is smaller, owing to its higher vegetation coverage, greater precipitation, and larger particulate matter size. Of the five main areas that affect the Hexi region, the dust intensity in TD is the highest. However, its dust trajectory contribution to the study area is lower. This is because the dust is not elevated to the free atmosphere readily by the easterly wind, owing to the closed mountain basin location. The contribution of the dust trajectories in the QB to the study area is the lowest, mostly due to the low dust intensity in this region and the obstruction of dust trajectories by the Qilian Mountains.