Asian Dust Storm Events Research Articles

LIDAR measurements of the vertical aerosol profile and optical depth during the ACE-Asia 2001 IOP, at Gosan, Jeju Island, Korea.

In order to investigate the characteristic of optical properties of Asian dust particles, the atmospheric aerosol vertical profile was measured with the multi-wavelength LIDAR system, at the Gosan super site (33 degrees 17'N, 126 degrees 10'E) in Jeju Island, Korea, during the ACE-Asia intensive observation period, 11 March-4 May 2001. An air mass backward trajectory analysis, using Hysplit-4, was carried out to track the aerosol plume, with high mass loading, from the Chinese desert regions during the period of Asian dust storm events. Vertical atmospheric aerosol profiles on three major Asian dust storm event days, 22 March and 13 and 26 April 2001, have been analyzed. The LIDAR-derived aerosol optical depth values were compared with those measured by a collocated sunphotometer.

Properties of individual Asian dust storm particles collected at Kosan, Korea during ACE-Asia

Abstract For the purpose of studying the properties of individual Asian dust storm particles, an intensive field measurement took place at the Kosan ground-based station located on the west coast of Cheju Island, Korea during ACE-Asia campaign. A 2-stage filter pack sampler was employed in the size-resolved (coarse and fine fractions) particle sampling. The trace elements of individual coarse particles (>1.2 μm) were analyzed by the X-ray microprobe analysis system equipped at SPring-8. The result of statistical analysis suggested that individual particles collected in Asian dust storm event could be classified into four groups: sea-salt-rich particles, crustal-rich particles, crustal/sea-salt/sulfur-rich particles, and crustal/sea-salt-rich particles. Moreover, according to the XRF elemental maps and elemental masks replayed corresponding to individual particles, particles could be categorized into two groups, namely internally mixed particles and externally mixed particles. A small part of the CaCO 3 in Asian dust storm particles would be converted to CaSO 4 through the chemical reaction between CaCO 3 and H 2 SO 4 during long-range transport. By means of XANES method, the major chemical state of Fe in Fe-rich particles was found to be Fe 3+ . Several minor trace heavy metals were probably affected by the air masses passed directly over the industrial areas of China.

Asian dust storm events of spring 2001 and associated pollutants observed in New England by the Atmospheric Investigation, Regional Modeling, Analysis and Prediction (AIRMAP) monitoring network

Between 18 April and 13 May 2001, three statistically extreme dust aerosol events were observed across the entire northeastern United States. High levels of bulk aerosol water‐soluble Ca2+ (range = 42–482 pptv) and PM2.5 elemental Ca (range = 19–156 pptv) were observed simultaneously at Atmospheric Investigation, Regional Modeling, Analysis and Prediction (AIRMAP) and Interagency Monitoring of Protected Visual Environments (IMPROVE) stations. On the basis of Ca2+ concentrations, the average bulk dust concentration for all events across all four AIRMAP stations was estimated to be 7.4 μg/m3. There was no evidence of dust outbreaks in North America large enough to explain these events. However, in April 2001, massive dust storms occurred in the Tarim Pendi basin and in the Gobi deserts of southern Mongolia and China. Comparison of elemental ratios of AIRMAP samples to previously reported Asian dust aerosol samples showed that all AIRMAP samples had a chemical composition similar to Asian dust transported over long distances. Within the dust plumes, strong correlations were observed between absorption, scattering, and CO, indicative of an anthropogenic contribution including elemental carbon and SO42− aerosols. Aerosol NO3− was also highly elevated during event days, most likely due to uptake of HNO3 by the dust during transport. A comparison of dust plumes sampled by AIRMAP to those sampled off the Asian coast during the TRACE‐P airborne mission and on the U.S. west coast, strongly suggested entrainment of additional pollutants (e.g., CO, aerosol NO3−, and SO42−) as the dust plumes were transported over North America.

Determination of the chemical properties of residues retained in individual cloud droplets by XRF microprobe at SPring-8

To determine the chemical properties of residue retained in individual cloud droplets is primarily important for the understanding of rainout mechanism and aerosol modification in droplet. The sampling of individual cloud droplets were carried out on the summit of Mt. Taiko located in Tango peninsula, Kyoto prefecture, during Asian dust storm event in March of 2002. XRF microprobe system equipped at SPring-8, BL-37XU was applied to the subsequent quantification analysis of ultra trace elements in residues of individual cloud droplets. It was possible to form the replicas of separated individual cloud droplets on the thin collodion film. The two dimensional XRF maps for the residues in individual cloud droplets were clearly drawn by scanning of micro-beam. Also, XRF spectra of trace elements in residues were well resolved. From the XRF spectra for individual residues, the chemical mixed state of residues could be assumed. The chemical forms of Fe (Fe +++) and Zn (Zn +) could be clearly characterized by their K-edge micro-XANES spectra. By comparison of Z/Si mass ratios of residues in cloud droplets and those of the original sands collected in desert areas in China, the aging of ambient dust particles and their in cloud modification were indirectly assumed.

Assessment of the photochemistry of OH and NO 3 on Jeju Island during the Asian-dust-storm period in the spring of 2001

In this study, we examined the influence of the long-range transport of dust particles and air pollutants on the photochemistry of OH and NO 3 on Jeju Island, Korea (33.17°N, 126.10°E) during the Asian-dust-storm (ADS) period of April 2001. Three ADS events were observed during the periods of April 10–12, 13–14, and 25–26. Average concentration levels of daytime OH and nighttime NO 3 on Jeju Island during the ADS period were estimated to be about 1 × 10 6 and 2 × 10 8 molecules cm −3 (∼9 pptv), respectively. OH levels during the ADS period were lower than those during the non-Asian-dust-storm (NADS) period by a factor of 1.5. This was likely to result from higher CO levels and the significant loading of dust particles, reducing the photolysis frequencies of ozone. Decreases in NO 3 levels during the ADS period was likely to be determined mainly by the enhancement of the N 2O 5 heterogeneous reaction on dust aerosol surfaces. Averaged over 24 h, the reaction between HO 2 and NO was the most important source of OH during the study period, followed by ozone photolysis, which contributed more than 95% of the total source. The reactions with CO, NO 2, and non-methane hydrocarbons (NMHCs) during the study period were major sinks for OH. The reaction of N 2O 5 on aerosol surfaces was a more important sink for nighttime NO 3 during the ADS due to the significant loading of dust particles. The reaction of NO 3 with NMHCs and the gas-phase reaction of N 2O 5 with water vapor were both significant loss mechanisms during the study period, especially during the NADS. However, dry deposition of these oxidized nitrogen species and a heterogeneous reaction of NO 3 were of no importance.

Effects of Asian dust storm events on daily mortality in Taipei, Taiwan

In spring, windblown dust storms originating in the deserts of Mongolia and China make their way to Taipei City. These occurrences are known as Asian dust storm events. The objective of this study was to assess the possible effects of Asian dust storms on the mortality of residents in Taipei, Taiwan, during the period from 1995 to 2000. We identified 39 dust storm episodes, which were classified as index days. Daily deaths on the index days were compared with deaths on the comparison days. We selected two comparison days for each index day, 7 days before the index day and 7 days after the index day. The strongest estimated effects of dust storms were increases of 7.66% in risk for respiratory disease 1 day after the event, 4.92% for total deaths 2 days following the dust storms and 2.59% for circulatory diseases 2 days following the dust storms. However, none of these effects were statistically significant. This study found greater specificity for associations with respiratory deaths, and this increases the likelihood that the association between dust events and daily mortality represents a causal relationship.

Aerosol distributions and radiative forcing over the Asian Pacific region simulated by Spectral Radiation‐Transport Model for Aerosol Species (SPRINTARS)

A three‐dimensional aerosol transport‐radiation model coupled with a general circulation model, Spectral Radiation‐Transport Model for Aerosol Species (SPRINTARS), simulates atmospheric aerosol distributions and optical properties. The simulated results are compared with aerosol sampling and optical observations from ground, aircraft, and satellite acquired by intensive observation campaigns over east Asia in spring 2001. Temporal variations of the aerosol concentrations, optical thickness, and Ångström exponent are in good agreement between the simulation and observations. The midrange values of the Ångström exponent, even at the Asian dust storm events over the outflow regions, suggest that the contribution of the anthropogenic aerosol, such as carbonaceous and sulfate, to the total optical thickness is of an order comparable to that of the Asian dust. The radiative forcing by the aerosol direct and indirect effects is also calculated. The negative direct radiative forcing is simulated to be over −10 W m−2 at the tropopause in the air mass during the large‐scale dust storm, to which both anthropogenic aerosols and Asian dust contribute almost equivalently. The direct radiative forcing, however, largely depends on the cloud water content and the vertical profiles of aerosol and cloud. The simulation shows that not only sulfate and sea salt aerosols but also black carbon and soil dust aerosols, which absorb solar and thermal radiation, make strong negative radiative forcing by the direct effect at the surface, which may exceed the positive forcing by anthropogenic greenhouse gases over the east Asian region.

Quantification on the source/receptor relationship of primary pollutants and secondary aerosols by a Gaussian plume trajectory model: Part III—Asian dust-storm periods

Characteristics of pollutants at heights in the top of the Planetary Boundary Layer (PBL) are collected and used in a local-scale model. A subsidence mechanism is developed to quantify the concentration fraction from the top PBL to simulate PM concentration during Asian dust-storm (ADS) periods. The results show that using the data measured at a mountain station, which is very vulnerable to ADS, as the top boundary conditions for the air quality model can capture all the PM2.5 episodes due to local sources and ADS events, at a low-altitude urban station. The correlation coefficient (r2) of daily PM2.5−10 concentration has increased from 0.17 to 0.62 by incorporating the subsidence mechanism, and that of PM2.5 increases as well. The model results of nitrate, sulfate and ammonium aerosol in fine radii can be compared with observations. According to our analysis, five out of eight PM2.5 or PM10 episode days occurred on ADS days in the past 4 years (1999–2002). During ADS episodes in 2000, 12% of PM2.5 and 53% of PM2.5−10 were from ADS dust. In addition, two dry deposition algorithms are evaluated; the algorithm of Seinfeld and Pandis (Atmospheric Chemistry and Physics from Air Pollution to Climate Change, Wiley, New York, 1998, 1057pp.) is suggested in this case study.

Chemical speciation of individual atmospheric particles using low- Z electron probe X-ray microanalysis: : characterizing “Asian Dust” deposited with rainwater in Seoul, Korea

Chemical speciation of individual microparticles is of much interest in environmental atmospheric chemistry; e.g. the determination of the elemental concentrations in individual atmospheric aerosol particles is important to study the chemical behavior of atmospheric pollution. Recently, an EPMA technique using an X-ray detector equipped with an ultra-thin window, allowing EPMA to determine concentrations of low- Z elements, such as C, N, and O, in individual particles of micrometer size, has been developed. This technique, called low- Z electron probe X-ray microanalysis (low- Z EPMA), is applied to characterize the water-insoluble part of “Asian Dust”, deposited by washout in the form of rainwater during an Asian Dust storm event and collected in Seoul, Korea. In this study, it was demonstrated that the single particle analysis using low-Z EPMA provided detailed information on various types of chemical species in the sample. In addition to aluminosilicates, silicon oxide, iron oxide, and calcium carbonate particles, which are expected to be present, carbonaceous particles are also observed in a significant fraction. This unexpected finding that particle sample originated from an arid area contains significant amount of carbonaceous particles is supported by the investigation of a “China Loess” sample. In addition, we also performed single particle analysis for a local soil sample, in order to check the possible influence from local sources on “Asian Dust”. The characteristics of the local soil particle sample, e.g. the types of aluminosilicate particles and the abdundance of particles with deviating chemical species, are clearly different from “Asian Dust” and “China Loess” samples, whereas those two are similar, implying that the “Asian Dust” sample was not much influenced by local sources.

Preliminary studies on applications of micro-PIXE to atmospheric aerosols

To characterize the physical and chemical properties of the individual aerosol particles during Asian dust storm in Japan, micro-PIXE technique was applied in this study. Aerosol particles were sampled in Kyoto, Japan from the middle of March to the end of April 1999. Mass concentration in Asian dust storm events was roughly 3–5 times higher than that of the highest concentration measured in non-Asian dust storm seasons. Single particles were generally sharp-edged and irregular in shape and contained mostly crustal elements such as Si, Fe and Ca. Although in soils of the desert and loess areas in northwest of China S and Cl were not detected, significant concentrations of S and Cl were detected in coarse fraction during Asian dust storm event. Nearly all single particles in the coarse fraction existed as a mixed state of soil components and S.

Characteristics of single particles sampled in Japan during the Asian dust–storm period

To investigate the characteristics of Asian dust storm particles as single particles in Japan, we measured morphology, composition and concentration of single particles using Scanning Electron Microscope (SEM) coupled with an energy dispersive X-ray microanalyzer (EDX), particle induced X-ray emission (PIXE) and micro-PIXE. Particles were sampled in Kyoto, Japan from the middle of April to the end of July 1999. Mass concentration in Asian dust–storm events was roughly 3–5 times higher than that of the highest concentration measured in non-Asian dust storm seasons. Single particles were generally sharp-edged and irregular in shape and contained mostly crustal elements such as Si, Fe, Ca and Al. Particles which have more than 40% Si content comprised nearly 50% of coarse single particles in Asian dust storm events. Main concentration range of Al in single Asian dust storm particles was 10–20%, and those of Ca and Fe were below 10%. Even though S and Cl in soils of the desert and loess areas in northwest of China were not detected, significant concentration of S and Cl in coarse fraction in Asian dust storm event were detected in single particles. Especially, the maximum concentration of S in Asian dust storm event was about 5 times higher than that in non-Asian dust storm days. Every single particle in coarse fraction existed as the mixing state of soil components and S. Good agreement between the results of SEM–EDX analysis and that of micro-PIXE analysis was obtained in this study.

Asian Dust Storm and Their Impact on the Air Quality of Taiwan

Measurements of aerosols (PM1O) and other air pollutants at stations of the air quality monitoring network of Taiwan Environmental Protection Administration (EPA) from 1993 to 2000 are analyzed to evaluate the impact of Asian dust storm events on the air quality of Taiwan. Enhancements of PM10 at Yangming mountain station in northern Taiwan as well as coastal stations to the north and northeast turn out to be the key indicators in identifying unambiguously the major Asian dust storm events and to estimate the impact of these events on the PM10 over Taiwan. Our analysis shows that the major increases of PM10 at Yangming station occur in March, April, and May. They are clearly associated with the Asian dust storm events. On a yearly basis, the impact ranges from about 3% in southwestern cities to about 12% for Yangming station. On the monthly basis, the enhancements can be as large as 150% for a clean station such as Hengchun hear the southern tip of Taiwan. Although the major component of the observed PM10 enhancements is mineral dust, we estimate that sulfate and nitrate ions contribute to about one quarter of the enhancements. The corresponding enhancements for other air pollutants (i.e. CO, O3, NO2, and SO2) can be identified only occasionally because of high ambient values, large variability in concentrations, and other reasons.

Characterization of the winter atmospheric aerosols in Kyoto and Seoul using PIXE, EAS and IC

Characteristics of atmospheric aerosols in Kyoto, Japan and Seoul, Korea were investigated using particle-induced X-ray emission (PIXE), elemental analysis system (EAS) and ion chromatograph (IC). Atmospheric aerosols were collected into fine and coarse fractions using a two-stage filter pack sampler in Kyoto and Seoul in winter of 1998. PIXE was applied to analyze the middle and heavy elements with atomic number greater than 14 (Si), and EAS was applied to analyze the light elements such as H, C and N. The total mass concentration in Seoul was about two times higher than in Kyoto and the concentration of Ca, Si, and Ti that are mainly originated from soil were remarkably higher in Seoul. During an Asian dust storm event, the concentration of soil components increased dramatically and amounted to about 15 times higher than average concentration. The fine/coarse ratios of NH 4 +, NO 3 −, and SO 4 2− were extremely high in both sites. The fact that nearly 70% of fine particles in both Kyoto and Seoul consist of the light elements (N, C, and H) suggests the importance of light elements measurement. Good mass closure for fine particles with light element data was achieved.

Mineral particles collected in china and japan during the same Asian dust-storm event

Aerosol particles were collected at China and Japan in the same spring Asian dust-storm event of 1991 in order to study the change in composition of mineral aerosol particles during long range transport. It was found on the basis of a microchemical analysis that dust particles containing Mg, Al, Si, K, Ca and Fe were a major fraction of the aerosol particles collected at Hohhot and Beijing, China, and Nagasaki, Japan. A large fraction of the mineral aerosol particles was internally mixed with sea salt in Nagasaki. Present study suggests that the internal mixed particles were mainly produced by cloud processes through droplet coalescence.

Detection of an Asian dust storm event in Japan during April 1980

During April 1980 aerosol particles were sampled at five locations in Japan for a week which included an especially strong dust storm derived from the Asian mainland. Time sequence sampling by streakers and PIXE analysis for multi-elemental concentrations in 2.4 h time steps recorded the passage of the storm over Japan. At Niigata three distinct components could be identified: soil dust represented by Fe, sea spray represented by Cl, and air pollution represented by S. The three had different arrival and disappearance times although they were all present during most of the storm.