Spatial Distribution Of Dust Research Articles

Modeling Dust in East Asia by CESM and Sources of Biases.

East Asian dust has a significant impact on regional and global climate. In this study, we evaluate the spatial distributions and temporal variations of dust extinction profiles and dust optical depth (DOD) over East Asia simulated from the Community Earth System Model (CESM) with satellite retrievals from Luo et al. (2015a, 2015b) (L15), Yu et al. (2015) (Y15), and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) level 3 (CAL-L3) products. Both L15 and Y15 are based on CALIPSO products but use different algorithms to separate dust from non-dust aerosols. We find high model biases of dust extinction in the upper troposphere over the Taklamakan Desert, Gobi Desert, and Tibetan Plateau, especially in the summer (June-July-August, JJA). CESM with dust emission scheme of Kok et al. (2014a, 2014b) has the best agreement with dust extinction profiles and DOD from L15 in the Taklamakan Desert and Tibetan Plateau. CESM with the default dust emission scheme of Zender et al. (2003a) underpredicts DOD in the Tibetan Plateau compared with observations from L15 due to the underestimation of local dust emission. Large uncertainties exist in observations from L15, Y15, and CAL-L3 and have significant impacts on the model evaluation of dust spatial distributions. We also assess dust surface concentrations and 10 m wind speed with meteorological records from weather stations in the Taklamakan and Gobi Deserts during dust events. CESM underestimates dust surface concentrations at most weather stations due to the inability of CESM to capture strong surface wind events.

Resolved views on early galaxy evolution

AbstractResolved observations of star-forming galaxies at cosmic noon with the Hubble Space Telescope and large ground-based facilities provide a view on the spatial distribution of stars, gas and dust, and probe gaseous motions revealing the central gravitational potential and local feedback processes at play. In this paper, we review recent insights gained from such observations, with an emphasis on results obtained through optical/near-infrared imaging and imaging spectroscopy. Their context and implications are documented more fully in a forthcoming review article by Förster Schreiber & Wuyts (in prep).

Structure and dynamics of high-z galaxies

AbstractHST and integral-field spectroscopic observations of star-forming galaxies at cosmic noon provide a view on the spatial distribution of stars, gas and dust, and probe gaseous motions revealing the central gravitational potential and local feedback processes at play. In this paper, we review recent insights gained from such observations, with an emphasis on results obtained through near-infrared imaging spectroscopy. Their context and implications are documented more fully in a forthcoming review article by Förster Schreiber & Wuyts (in prep).

Interplanetary Dust, Meteoroids, Meteors and Meteorites

Interplanetary dust particles and meteoroids mostly originate from comets and asteroids. Understanding their distribution in the Solar system, their dynamical behavior and their properties, sheds light on the current state and the dynamical behavior of the Solar system. Dust particles can endanger Earth-orbiting satellites and deep-space probes, and a good understanding of the spatial density and velocity distribution of dust and meteoroids in the Solar system is important for designing proper spacecraft shielding. The study of interplanetary dust and meteoroids provides clues to the formation of the Solar system. Particles having formed 4.5 billion years ago can survive planetary accretion and those that survived until now did not evolve significantly since then. Meteoroids and interplanetary dust can be observed by measuring the intensity and polarization of the zodiacal light, by observing meteors entering the Earth’s atmosphere, by collecting them in the upper atmosphere, polar ices and snow, and by detecting them with in-situ detectors on space probes.

Inversion and Effect Research on Dust Distribution of Urban Forests in Beijing

Urban forests affect the filtration and absorption of airborne particulate matter, which can minimize the harmful effects to human health caused by airborne particulate pollution. Evergreen plants in urban forests play a major role in absorbing dust and purifying the air, especially in winter. Studying the spatial distribution of leaf dust and exploring the dust retention effect of evergreen shrubs are important for scientifically guiding urban forest construction and improving the living environment of cities in winter. The purpose of this study was to establish a dust inversion model by correlation analysis of spectral reflectance and the amount of dust absorption (ADA) of vegetation, using Sentinel-2 satellite remote-sensing images to obtain the dust distribution of the evergreen vegetation (mainly Euonymus japonicus Thunb.) in the Beijing urban area, and to determine the effect of the spatial pattern of E. japonicus woodland on ADA intensity. The result showed that the red band and near-infrared band are most sensitive to dust. The normalized difference phenology index (NDPI) is more suitable for building an inversion model, where the determination coefficient (R2) of the inversion model constructed by the ratio of the NDPI (RNDPI) was 0.879. The inversion results show that the mean ADA in the enclosed area is smaller than that in semi-enclosed and open areas, and the regional distribution of high ADA in the urban area of Beijing was higher in the south with a tendency of the ADA to decrease from city center to the surrounding area. The size, shape, and percentage of landscape (PLAND) of E. japonicus woodland have a significant effect on ADA intensity. We found that, in the study area, when the PLAND of E. japonicus woodland is higher than 40%, its ADA intensity remains basically unchanged. When the vegetation coverage is fixed, the landscape shape index is negatively correlated with ADA intensity, and reduction of the overall shape complexity of forestland can enhance its dust retention effect and improve the air environment of the surrounding areas. The results of this study can be used as a reference for urban planners and landscape architects when building urban forests, providing a scientific basis for controlling and reducing air particulate pollution in Beijing’s winter and improving the living environment.

Spatial and Temporal Variations in the Incidence of Dust Storms in Saudi Arabia Revealed from In Situ Observations

Monthly meteorological data from 27 observation stations provided by the Presidency of Meteorology and Environment (PME) of Saudi Arabia were used to analyze the spatial and temporal distribution of atmospheric dust in Saudi Arabia between 2000 and 2016. These data were used to analyze the effects of environmental forcing on the occurrence of dust storms across Saudi Arabia by considering the relationships between dust storm frequency and temperature, precipitation, and wind variables. We reveal a clear seasonality in the reported incidence of dust storms, with the highest frequency of events during the spring. Our results show significant positive relationships (p < 0.005) between dust storm occurrence and wind speed, wind direction, and precipitation. However, we did not detect a significant relationship with temperature. Our results reveal important spatial patterns, as well as seasonal and inter-annual variations, in the occurrence of dust storms in Saudi Arabia. For instance, the eastern part of the study area experienced an increase in dust storm events over time, especially in the region near Al-Ahsa. Similarly, an increasing trend in dust storms was also observed in the west of the study area near Jeddah. However, the occurrence of dust storm events is decreasing over time in the north, in areas such as Hail and Qaisumah. Overall, the eastern part of Saudi Arabia experiences the highest number of dust storms per year (i.e., 10 to 60 events), followed by the northern region, with the south and the west having fewer dust storm events (i.e., five to 15 events per year). In addition, our results showed that the wind speeds during a dust storm are 15–20 m/s and above, while, on a non-dust day, the wind speeds are approximately 10–15 m/s or lower. Findings of this study provide insight into the relationship between environmental conditions and dust storm occurrence across Saudi Arabia, and a basis for future research into the drivers behind these observed spatio-temporal trends.

Study of the Explosibility Characteristics of Aluminium-Silver Metal Mixtures

ABSTRACTWhen two combustible powders mixed as solid/solid mixtures, the physical and chemical properties of both types of dust have an impact on cloud flammability and its explosivity. This study is mainly focused on aluminium-silver mixtures as they are suitable candidates for semiconductor industries and passivated emitter and rear contact (PERC) manufacturing. In order to assess the explosivity of aluminium-silver clouds, studying the effects of particle size distribution, by mixing weight ratio and powder concentrations, has been carried out in a 0.012 m3 cylindrical vessel. In particular, on nanoscales, the explosion characteristics of aluminium powder were different when compared to the silver venting explosion, as the size of the particles was reduced from 70 to 40 nm. The results also showed that Pred was reduced by about one third when 50% wt. silver was introduced to nanoaluminium powder mixtures. Moreover, by mixing the two metals, it modified the mean particle size and the spatial dust distribution in the test vessel, impacting the uniformity of the dust cloud, especially when the silver particle size was 10 µm. The present work demonstrates that, silver exhibited a ‘suppressing effect’ on aluminium/silver mixtures explosion, and this condition was explored in this work.

Evolution of Solids in Planet Forming Disks: The Interplay of Experiments, Simulations, and Observations.

Circumstellar dust analogues can be studied experimentally to determine their col- lisional behavior and their optical properties. These results affect simulations of circumstellar disks in various, substantial ways: Collision results determine how dust aggregates grow and how their aerodynamic properties change with time. This determines how solids move throughout the disk, how they accumulate, and how planetesimals might be formed. The optical properties determine the observational signature of these effects and allow us to constrain the spatial distribution of dust in disks, the sizes of the aggregates, as well as the temperature and optical depth of the dust emission. In this contribution, it is discussed how theoretical models and their predictions depend on laboratory results and what we learned about disks from high spatial resolution radio interferometry.

Development of a dynamic dust source map for NMME-DREAM v1.0 model based on MODIS Normalized Difference Vegetation Index (NDVI) over the Arabian Peninsula

Abstract. We developed a time-dependent dust source map for the NMME Dust Regional Atmospheric Model (DREAM v1.0) based on the satellite MODIS Normalized Difference Vegetation Index (NDVI). Areas with NDVI <0.1 are classified as active dust sources. The updated modeling system is tested for dust emission capabilities over SW Asia using a mesoscale model grid increment of 0.1∘×0.1∘ for a period of 1 year (2016). Our results indicate significant deviations in simulated aerosol optical depths (AODs) compared to the static dust source approach and general increase in dust loads over the selected domain. Comparison with MODIS AOD indicates a more realistic spatial distribution of dust in the dynamic source simulations compared to the static dust sources approach. The modeled AOD bias is improved from −0.140 to 0.083 for the case of dust events (i.e., for AOD >0.25) and from −0.933 to −0.424 for dust episodes with AOD >1. This new development can be easily applied to other time periods, models, and different areas worldwide for a local fine tuning of the parameterization and assessment of its performance.

Numerical Dust Storm Simulation Using Modified Geographical Domain and Data Assimilation: 3DVAR and 4DVAR (WRF-Chem/WRFDA)

Dust storms have severe environmental, economic, health, weather, and climate change impacts. A severe dust storm that hit Egypt on 22 January 2004 was selected as a case study to establish an accurate numerical model to simulate dust storms over Egypt using the Weather Research Forecast with a chemistry module (WRF-Chem). Two simulation setups using WRF-Chem were conducted using two geographic domains: the first exclusively included dust sources within Egypt, while the second included an external dust source, the Bodele Depression in southwestern Chad. The first simulation was only able to capture the core of the dust plume from the internal dust source Egyptian Qattara Depression, but the second was able to capture the spatial dust distribution from both the Qattara Depression and the Bodele Depression. Moreover, the results from our second simulation model had less errors than comparable results using moderate resolution imaging spectroradiometer (MODIS). We then investigated the impact of meteorological data assimilation methods using both three-dimensional and four-dimensional variational assimilation algorithms to simulate the aerosol optical depth of the dust storm using weather research forecast data assimilation (WRFDA) framework.

Identification of dust transport patterns and sources by using MODIS: a technique developed to discriminate dust and clouds

This study focuses on exploring the meteorological factors behind dust emergence and spread over Baluchistan in the post-monsoon season, as much of the existing research has been done on spring episodes. With the integration of remote sensing and meteorological methods, efforts were made to explore the relationship of dust storms with land-atmospheric conditions like surface temperature and aerosol optical depth (AOD) in the selected season. To map dust spatial distribution, a cloud-free product of brightness temperature difference (BTD) composite from MODIS terra level 1B emissive bands was prepared and classified using maximum likelihood technique. Two case studies of October 2004 and December 2011 exhibited the short-term cooling effect on the surface due to increased AOD. Dominant synoptic patterns of cold trough front formation with low-pressure centre development over eastern Iran were found as a significant feature of dust mobility towards warmer Baluchistan. Back trajectory analysis revealed that dust from south western Kazakhstan and eastern Europe converged over land of Kyrgyzstan and Tajikistan, which may have instigated its uplift over Helmand Basin. Evidence of a dominant effect of air masses from Middle East, Iran and Iraq was found in post-monsoon dust episodes.

The Interstellar Dust Properties of Nearby Galaxies

This article gives an overview of the constitution, physical conditions, and observables of dust in the interstellar medium of nearby galaxies. We first review the macroscopic, spatial distribution of dust in these objects and its consequences for our ability to study grain physics. We also discuss the possibility of using dust tracers as diagnostic tools. We then survey the current understanding of the microscopic, intrinsic properties of dust in different environments, derived from different observables: emission, extinction, polarization, and depletions, over the whole electromagnetic spectrum. Finally, we summarize the clues about grain evolution, evidenced either on local scales or over cosmic time. We put in perspective the different evolution scenarios. We attempt a comprehensive presentation of the main observational constraints, analysis methods, and modeling frameworks of the distinct processes. We discuss neither the dust properties of the Milky Way and distant galaxies, nor circumstellar or active galactic nucleus torus dust.

Study and Simulation of Severe Dust Storms in the West and Southwest of Iran

In recent decades, the number of dust events has increased significantly in the west and southwest of Iran. In this research, a survey on the dust events during the period 1990–2013 is carried out using historical dust data collected from seven synoptic stations scattered across the west and southwest of Iran. Using statistical analysis of the observational data, two of the most severe dust storm events that occurred in the region on July 4–7, 2009 and June 17–20, 2012 were selected and analyzed synoptically. NCEP/NCAR reanalysis dataset was used to obtain the required fields including sea level pressure, surface wind field, geopotential height at 500 hPa, and wind and vertical motion at the 850 hPa level. Moreover, weather research and forecasting model coupled with chemistry (WRF-Chem) with two aerosol schemes, GOCART and MADE/SORGAM, were used to simulate the amount of particulate matter (PM10) and its transportation over the studied region. The initial and lateral boundary conditions of the model simulations are provided by Global Forecast System (GFS) data with the horizontal resolution of 0.5°. The calculations demonstrated that the MADE/SORGAM scheme predicted the values and trends of PM10 better than GOCART. Dust plums are formed over Iraq and Syria and then transported to the west and southwest of Iran. Comparing the MODIS satellite images for July 4, 2009 and June 18, 2012 with the corresponding model output showed the good performance of WRF-Chem in simulating the spatial distribution of dust.

On deviations from free-radial outflow in the inner coma of comet 67P/Churyumov–Gerasimenko

The Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) onboard the European Space Agency's Rosetta spacecraft acquired images of comet 67P/Churyumov–Gerasimenko (67P) and its surrounding dust coma starting from May 2014 until September 2016. In this paper we present methods and results from analysis of OSIRIS images regarding the dust outflow in the innermost coma of 67P. The aim is to determine the global dust outflow behaviour and place constraints on physical processes affecting particles in the inner coma. We study the coma region right above the nucleus surface, spanning from the nucleus centre out to a distance of about 50 km comet centric distance (approximately 25 average comet radii). We primarily adopt an approach used by Thomas and Keller (1990) to study the dust outflow. We present the effects on azimuthally-averaged values of the dust reflectance of non-radial flow and non-point-source geometry, acceleration of dust particles, sublimation of icy dust particles after ejection from the surface, dust particle fragmentation, optical depth effects and the influence of gravitationally bound particles. All of these physical processes could modify the observed distribution of light scattered by the dust coma.In the image analysis, profiles of azimuthally averaged dust brightness as a function of impact parameter b (azimuthal average, “Ā-curve”) were fitted with a simple function that best fits the shape of our profile curves (f(b;u,v,w,z)=u/bv+wb+z). The analytical fit parameters (u, v, w, z), which hold the key information about the dust outflow behaviour, were saved in a comprehensive database.Through statistical analysis of these information, we show that the spatial distribution of dust follows free-radial outflow behaviour (i.e. force-free radial outflow with constant velocity) beyond distances larger than ∼11.9 km from the comet centre, which corresponds to a relative distance of about 6 average comet radii from the comet centre. Hence, we conclude that beyond this distance, and on average, fragmentation and gravitationally bound particles are negligible processes in determining the optically scattered light distribution in the innermost coma. Closer to the nucleus we observe dust outflow behaviour that deviates from free-radial outflow.A comparison of our result profiles with numerical models using a Direct Simulation Monte Carlo (DSMC) approach with dust particle distributions calculated using a test particle approach has been used to demonstrate the influence of a complex shape and particle acceleration on the azimuthal average profiles. We demonstrate that, while other effects such as fragmentation or sublimation of dust particles cannot be ruled out, acceleration of the dust particles and effects arising from the shape of the irregular nucleus (non-point source geometry) are sufficient to explain the observed dust outflow behaviour from image data analysis.As a by-product of this work, we have calculated “Afρ” values for the 1/r regime. We found a peak in the coma activity in terms of Afρ (normalised to a phase angle of 90°) of ∼210 cm 20 days after perihelion. Furthermore, based on simplified models of particle motion within bound orbits, it is shown that limits on the total cross-sectional area of bound particles might be derived through further analysis. An example is given.

Performance Evaluation of WRF-CHEM in Simulating Harmattan Dust over West Africa

In this study, we investigated the ability of Weather Research and Forecasting model coupled with the Chemistry option (WRF-Chem) using the GOCART dust scheme in capturing the spatial and temporal distribution of a severe dust storm which occurred in March 2006 over West Africa. The period (5th - 14th March, 2006) also coincided with the African Monsoon Multidisciplinary Analysis (AMMA) Special Observing Period (SOP) and some observed datasets from other platforms were also used. The WRF-Chem simulation was performed on a two-way nested domain in order to resolve the dust episode on high horizontal resolution dataset. From the 5th March, a dust storm raised in northern Algeria, which propagated southward spreading to the west and east on the subsequent days. Over the Gulf of Guinea, an intense dust haze was transported southward thereby generating an aerosol optical thickness (AOT) greater than 4 over Nigeria. Qualitative and quantitative characterizations between observations and WRF-Chem simulations demonstrated that the WRF-Chem model is highly efficient and can be recommended to simulate the spatial and temporal distribution of harmattan dust over West Africa. We discovered that the WRFChem modelled Aerosol Optical Depth (AOD) underestimated the AOD from AERONET as a result of all other aerosols like black carbon integrated into the observed which is not yet captured by model. The quantitative and qualitative analysis of the model output ascertain the capability of WRF-Chem to reasonably reproduce West African harmattan dust haze from the time and location of being raised to its transportation and propagation and hence its final settling or disappearance over the continental area of West Africa. Model simulation was able to partition the dust particles into five different sizes. It was discovered that dust particles of sizes 1.4 μm, 2.4 μm and 4.5 μm are more prevalent among other sizes from the raised and transported dust over West Africa.

Understanding the dust properties in nearby galaxies

Dust is a crucial component in the interstellar medium of galaxies. It regulates several physical and chemical processes. Dust grains are also efficient at absorbing and scattering ultraviolet/optical photons and then re-radiating the absorbed energy in the infrared/submm wavelength range. The spatial distribution and properties of dust in galaxies can hence be investigated in two complementary ways: by its attenuation effects at short wavelengths, and by its thermal emission at long wavelengths. Both approaches have their advantages and challenges. In this contribution, we discuss a number of recent interesting results on interstellar dust in nearby galaxies, obtained by our research group at Ghent University.

Investigating the size, shape and surface roughness dependence of polarization lidars with light-scattering computations on real mineral dust particles: Application to dust particles' external mixtures and dust mass concentration retrievals

Our understanding of the contribution of mineral dust to the Earth's radiative budget is limited by the complexity of these particles, which present a wide range of sizes, are highly-irregularly shaped, and are present in the atmosphere in the form of particle mixtures. To address the spatial distribution of mineral dust and atmospheric dust mass concentrations, polarization lidars are nowadays frequently used, with partitioning algorithms allowing to discern the contribution of mineral dust in two or three-component particle external mixtures. In this paper, we investigate the dependence of the retrieved dust backscattering (βd) vertical profiles with the dust particle size and shape. For that, new light-scattering numerical simulations are performed on real atmospheric mineral dust particles, having determined mineralogy (CAL, DOL, AGG, SIL), derived from stereogrammetry (stereo-particles), with potential surface roughness, which are compared to the widely-used spheroidal mathematical shape model. For each dust shape model (smooth stereo-particles, rough stereo-particles, spheroids), the dust depolarization, backscattering Ångström exponent, lidar ratio are computed for two size distributions representative of mineral dust after long-range transport. As an output, two Saharan dust outbreaks involving mineral dust in two, then three-component particle mixtures are studied with Lyon (France) UV–VIS polarization lidar. If the dust size matters most, under certain circumstances, βd can vary by approximately 67% when real dust stereo-particles are used instead of spheroids, corresponding to variations in the dust backscattering coefficient as large as 2Mm−1·sr−1. Moreover, the influence of surface roughness in polarization lidar retrievals is for the first time discussed. Finally, dust mass-extinction conversion factors (ηd) are evaluated for each assigned shape model and dust mass concentrations are retrieved from polarization lidar measurements. From spheroids to stereo-particles, ηd increases by about 30%. We believe these results may be useful for our understanding of the spatial distribution of mineral dust contained in an aerosol external mixture and to better quantify dust mass concentrations from polarization lidar experiments.

The effect of radiation pressure on spatial distribution of dust inside H ii regions

We investigate the impact of radiation pressure on spatial dust distribution inside H$_\mathrm{II}$ regions using one-dimensional radiation hydrodynamic simulations, which include absorption and re-emission of photons by dust. In order to investigate grain size effects as well, we introduce two additional fluid components describing large and small dust grains in the simulations. Relative velocity between dust and gas strongly depends on the drag force. We include collisional drag force and coulomb drag force. We find that, in a compact H$_\mathrm{II}$ region, a dust cavity region is formed by radiation pressure. Resulting dust cavity sizes (~0.2 pc) agree with observational estimates reasonably well. Since dust inside an H$_\mathrm{II}$ region is strongly charged, relative velocity between dust and gas is mainly determined by the coulomb drag force. Strength of the coulomb drag force is about 2-order of magnitude larger than that of the collisional drag force. In addition, in a cloud of mass $10^5$ $M_{\odot}$, we find that the radiation pressure changes the grain size distribution inside H$_\mathrm{II}$ regions. Since large (0.1 $\mathrm{\mu m}$) dust grains are accelerated more efficiently than small (0.01 $\mathrm{\mu m}$) grains, the large to small grain mass ratio becomes smaller by an order of magnitude compared with the initial one. Resulting dust size distributions depend on the luminosity of the radiation source. The large and small grain segregation becomes weaker when we assume stronger radiation source, since dust grain charges become larger under stronger radiation and hence coulomb drag force becomes stronger.

Spatial distribution of carbon dust in the early solar nebula and the carbon content of planetesimals

A high fraction of carbon bound in solid carbonaceous material is observed to exist in bodies formed in the cold outskirts of the solar nebula, while bodies in the terrestrial planets region contain nearly none. We study the fate of the carbonaceous material during the spiral-in of matter as the sun accretes matter from the solar nebula. From observational data on the composition of the dust component in comets and interplanetary dust particles, and from data on pyrolysis experiments, we construct a model for the composition of the pristine carbonaceous material in the outer parts of the solar nebula. We study the pyrolysis of the refractory and volatile organic component and the concomitant release of high-molecular-weight hydrocarbons under quiescent conditions of disk evolution where matter migrates inwards. We also study the decomposition and oxidation of the carbonaceous material during violent flash heating events, which are thought to be responsible for the formation of chondrules. It is found that the complex hydrocarbon components are removed from the solid disk matter at temperatures between 250 and 400 K, while the amorphous carbon component survives up to 1200 K. Without efficient carbon destruction during flash-heating associated with chondrule formation the carbon abundance of terrestrial planets, except for Mercury, would be not as low as it is found in cosmochemical studies. Chondrule formation seems to be a process that is crucial for the carbon-poor composition of the material of terrestrial planets.

Gaps and rings carved by vortices in protoplanetary dust

Context. Large-scale vortices in protoplanetary disks are thought to form and survive for long periods of time. Hence, they can significantly change the global disk evolution and particularly the distribution of the solid particles embedded in the gas, possibly explaining asymmetries and dust concentrations recently observed at submillimeter and millimeter wavelengths. Aims. We investigate the spatial distribution of dust grains using a simple model of protoplanetary disk hosted by a giant gaseous vortex. We explore the dependence of the results on grain size and deduce possible consequences and predictions for observations of the dust thermal emission at submillimeter and millimeter wavelengths. Methods. Global 2D simulations with a bi-fluid code are used to follow the evolution of a single population of solid particles aerodynamically coupled to the gas. Possible observational signatures of the dust thermal emission are obtained using simulators of ALMA and Nest Generation Very Large Array (ngVLA) observations. Results. We find that a giant vortex not only captures dust grains with Stokes number St< 1 but can also affect the distribution of larger grains (with St ~ 1) carving a gap associated with a ring composed of incompletely trapped particles. The results are presented for different particle sizes and associated with their possible signatures in disk observations. Conclusions. Gap clearing in the dust spatial distribution could be due to the interaction with a giant gaseous vortex and their associated spiral waves without the gravitational assistance of a planet. Hence, strong dust concentrations at short sub-mm wavelengths associated with a gap and an irregular ring at longer mm and cm wavelengths could indicate the presence of an unseen gaseous vortex.