Severe Dust Event Research Articles

Numerical Studies on a Severe Dust Storm in East Asia Using WRF-Chem

Dust storm is one of the important natural disasters, which can have significant impact on terrestrial ecosystem, global climate, air quality and human health. In Mar. 19-23, 2010, a serious dust storm occurred over East Asia. It started from Mongolia, initially extending to the east, turning to the South of China, then back to the Northeast Asia. About 20% of the areas in China suffered from this severe dust event and the air was heavily polluted with massive airborne particulates. The Air Pollution Index (API) in many cities exceeded 500 when dust storm passed by, while the maximum surface PM10 concentration reached 1900 &#181g/m3 in east area. The coarse particles were dominated in PM10, with fine particles named as PM2.5 only accounting for 5% - 20% at cities along the dust moving track in South and East China. MODIS and CALIPSO satellite data were used to investigate the horizontal and vertical patterns of optical parameters of dust aerosol. The average AOD reached 2 - 2.5 on dust days in most southeast regions. The dust can be transported up to 5 Km with maximum aerosol extinction coefficient of 0.35 - 0.4 at 1 - 3 Km in vertical. Synoptic weather was analyzed to understand the meteorological conditions and the backward trajectories were calculated to investigate the movements of air mass. The WRF-Chem model (Version 3.2) was applied to simulate the transport and deposition of the dust aerosols. The performance of Shaw (2008) and Chin (2002) parameterization schemes for dust emissions in WRF-Chem were evaluated. Modeling results were compared with the CUACE-Dust and RegCCMS. Investigations show that WRF-Chem has capability on simulations on dust emission, long range transport and deposition. Shaw (2008) scheme gives more reasonable spatial distribution of dust aerosols, while Chin (2002) scheme presents more better results in terms of PM10 surface concentration simulation. It is suggested that two schemes can be used at the same time in terms of simulation of dust pattern and concentration.

Case study of dust event sources from the Gobi and Taklamakan deserts: An investigation of the horizontal evolution and topographical effect using numerical modeling and remote sensing

A severe dust event occurred from April 23 to April 27, 2014, in East Asia. A state-of-the-art online atmospheric chemistry model, WRF/Chem, was combined with a dust model, GOCART, to better understand the entire process of this event. The natural color images and aerosol optical depth (AOD) over the dust source region are derived from datasets of moderate resolution imaging spectroradiometer (MODIS) loaded on a NASA Aqua satellite to trace the dust variation and to verify the model results. Several meteorological conditions, such as pressure, temperature, wind vectors and relative humidity, are used to analyze meteorological dynamic. The results suggest that the dust emission occurred only on April 23 and 24, although this event lasted for 5days. The Gobi Desert was the main source for this event, and the Taklamakan Desert played no important role. This study also suggested that the landform of the source region could remarkably interfere with a dust event. The Tarim Basin has a topographical effect as a “dust reservoir” and can store unsettled dust, which can be released again as a second source, making a dust event longer and heavier.

Synoptic characteristics of dusty spring days over central and eastern Saudi Arabia

The synoptic characteristics of dusty spring days in central and eastern Saudi Arabia were analyzed using the aerosol index (AI) from the TOMS satellite and meteorological parameters from the NCEP/NCAR reanalysis dataset. The AI distributions were used to detect and classify dusty spring days into three classes (narrow, moderate, and wide spread). The synoptic features of the cases and classes demonstrated the common synoptic characteristics that represented the dusty spring cases. The strength of these common synoptic characteristics was found to increase with increasing dust severity. Specifically, as the following factors occurred, the cyclone located over the southern Arabian Peninsula deepened, the maximum wind at 250 hPa weakened and shifted northward, the instability over the northern Arabian Peninsula increased, the northerly wind generated, and the gradient of the 850-hPa potential temperature west of the cyclone increased; the severity of the dust class increased. The results were confirmed by examining three specific cases representing weak, moderate, and severe dust events.

2010년 3월 극심한 황사사례의 발생 및 수송과정에 관한 연구

2010년 3월 극심한 황사사례의 발생 및 수송과정에 관한 연구

Significant impacts of heterogeneous reaction on the chemico-physical properties of dust particles during severe dust events over East Asia in 2015

Significant impacts of heterogeneous reaction on the chemico-physical properties of dust particles during severe dust events over East Asia in 2015

Numerical simulation of a dust event in northeastern Germany with a new dust emission scheme in COSMO-ART

Abstract The dust emission scheme of Shao (2004) has been implemented into the regional atmospheric model COSMO-ART and has been applied to a severe dust event in northeastern Germany on 8th April 2011. The model sensitivity to soil moisture and vegetation cover has been studied. Soil moisture has been found to be relatively high in the model during the investigation period and has been reduced by different degree to investigate the resulting changes in dust emissions. Two different vegetation datasets have been tested as model input: the climatological vegetation cover data of COSMO-ART (ECOCLIMAP) and the SPOT5 remote sensing vegetation cover data for the time of the event. By varying soil moisture, vegetation cover and by restricting the potential emission area, a set of eleven simulations was generated. Vegetation cover during the event was about 24% lower on average compared to the climatological mean. Thus, dust emissions modeled with SPOT5 vegetation exceeded that modeled with climatological data by a factor of about 5. The modeled dust concentrations were compared with in-situ measurements of aerosol concentration. The temporal evolutions of simulations and observations have significant correlations (0.42–0.85) especially in rural backgrounds. The lower correlations at urban sites are attributed to anthropogenic PM10 sources, which are not included in the model. However, a verification of the magnitude of modeled dust concentrations is not possible due to the uncertainty in soil moisture and emission area.

The impact of dust storms on the Arabian Peninsula and the Red Sea

Abstract. Located in the dust belt, the Arabian Peninsula is a major source of atmospheric dust. Frequent dust outbreaks and some 15 to 20 dust storms per year have profound effects on all aspects of human activity and natural processes in this region. To quantify the effect of severe dust events on radiation fluxes and regional climate characteristics, we simulated the storm that occurred from 18 to 20 March 2012 using a regional weather research forecast model fully coupled with the chemistry/aerosol module (WRF–Chem). This storm swept over a remarkably large area affecting the entire Middle East, northeastern Africa, Afghanistan, and Pakistan. It was caused by a southward propagating cold front, and the associated winds activated the dust production in river valleys of the lower Tigris and Euphrates in Iraq; the coastal areas in Kuwait, Iran, and the United Arab Emirates; the Rub al Khali, An Nafud, and Ad Dahna deserts; and along the Red Sea coast on the west side of the Arabian Peninsula. Our simulation results compare well with available ground-based and satellite observations. We estimate the total amount of dust generated by the storm to have reached 94 Mt. Approximately 78% of this dust was deposited within the calculation domain. The Arabian Sea and Persian Gulf received 5.3 Mt and the Red Sea 1.2 Mt of dust. Dust particles bring nutrients to marine ecosystems, which is especially important for the oligotrophic Northern Red Sea. However, their contribution to the nutrient balance in the Red Sea remains largely unknown. By scaling the effect of one storm to the number of dust storms observed annually over the Red Sea, we estimate the annual dust deposition to the Red Sea, associated with major dust storms, to be 6 Mt.

Numerical modeling of a strong dust event over the south China region in March 2010

The mesoscale model WRF-Chem was used to simulate a severe dust storm event that occurred in March 2010. The storm affected a vast area of East Asia, including the south China region and Hong Kong. This southern region is rarely affected by dust weather. The performance of the WRF-Chem was evaluated by observational data such as the National Center for Atmospheric Research reanalysis data for atmospheric circulation, PM10 concentration from various ground stations, and satellite images of Moderate Resolution Imaging Spectroradiometer and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations. The dependence of the model’s performance on certain important parameterizations was examined in this study. For this particular dust storm event, the model results suggest that the simulation is not very sensitive to certain key physical parameterizations such as threshold wind speed of dust emission and the choice of land surface model. In general, the WRF-Chem is capable of capturing the key physical processes for this severe dust event. The analysis of the dust transport fluxes suggests that the dust transport to the south China region is mainly from the north, although there is a mountainous region in the northern part of the south China region.

Quantitative analysis on windblown dust concentrations of PM10 (PM2.5) during dust events in Mongolia

Abstract Dust concentration, wind speed and visibility, measured at four sites in the Gobi Desert and at a site in the steppe zone of Mongolia over a period of 4.5 years (January 2009 to May 2013), have been analyzed for their relationships, their effects on visibility, and for an estimate of the threshold wind necessary for dust emission in the region. Based on quantitative analysis on measurements, we evaluated that dust emission concentrations of 41–61 (20–24) μg m −3 of PM 10 (PM 2.5 ) are as the criterion between normal and hazy atmospheric conditions. With the arrival of dust events, wind-borne soil particulate matter (PM 10 , PM 2.5 ) that originates in the Gobi Desert is changed dramatically. PM 10 (PM 2.5 ) concentrations increase by at least double or by several tens of times during severe dust events in comparison with the normal atmospheric condition. Ratio (PM 2.5 /PM 10 ) between monthly means of PM 10 and PM 2.5 concentrations showed that anthropogenic particles were dominant in the ambient air of province centers in cool months (November to February). Threshold values of the onset of dust events were determined for PM 10 (PM 2.5 ) concentrations. According to the definition of dust storms, dust concentrations of PM 10 corresponding to visibility of 1 km or less were determined at sites in the Gobi Desert and the steppe region. The threshold wind speeds during days with dust events were estimated at four sites in the Gobi Desert and compared each other. The threshold wind was higher at Sainshand and its cause might be due to smaller silt and clay fractions of soil.

Numerical simulation of dust events in the Middle East

Abstract In this paper, the severe dust event of 3–8 July 2009 in the Middle East is simulated using the WRF–DuMo model. To improve the model capacity in dust emission estimates, the effect of soil salt on threshold friction velocity for wind erosion is taken into consideration. A soil-salt propagation map and the other input parameters are compiled based on remote sensing and a Geographic Information System. The satellite images and synoptic data are used for the validation of the model results. Synoptic analysis is done for the Middle East and the synoptic systems for the severe dust event are identified. Comparison of the model results with the observed data shows that in the Aral–Caspian Sea area, central Iran and the Dead Sea Basin, dust emission is suppressed due to the high soil-salt content. The model shows better performances when the soil-salt effect is considered.

Numerical simulation of "an American haboob"

Abstract. A dust storm of fearful proportions hit Phoenix in the early evening hours of 5 July 2011. This storm, an American haboob, was predicted hours in advance because numerical, land–atmosphere modeling, computing power and remote sensing of dust events have improved greatly over the past decade. High-resolution numerical models are required for accurate simulation of the small scales of the haboob process, with high velocity surface winds produced by strong convection and severe downbursts. Dust productive areas in this region consist mainly of agricultural fields, with soil surfaces disturbed by plowing and tracks of land in the high Sonoran Desert laid barren by ongoing draught. Model simulation of the 5 July 2011 dust storm uses the coupled atmospheric-dust model NMME–DREAM (Non-hydrostatic Mesoscale Model on E grid, Janjic et al., 2001; Dust REgional Atmospheric Model, Nickovic et al., 2001; Pérez et al., 2006) with 4 km horizontal resolution. A mask of the potentially dust productive regions is obtained from the land cover and the normalized difference vegetation index (NDVI) data from the Moderate Resolution Imaging Spectroradiometer (MODIS). The scope of this paper is validation of the dust model performance, and not use of the model as a tool to investigate mechanisms related to the storm. Results demonstrate the potential technical capacity and availability of the relevant data to build an operational system for dust storm forecasting as a part of a warning system. Model results are compared with radar and other satellite-based images and surface meteorological and PM10 observations. The atmospheric model successfully hindcasted the position of the front in space and time, with about 1 h late arrival in Phoenix. The dust model predicted the rapid uptake of dust and high values of dust concentration in the ensuing storm. South of Phoenix, over the closest source regions (~25 km), the model PM10 surface dust concentration reached ~2500 μg m−3, but underestimated the values measured by the PM10 stations within the city. Model results are also validated by the MODIS aerosol optical depth (AOD), employing deep blue (DB) algorithms for aerosol loadings. Model validation included Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), equipped with the lidar instrument, to disclose the vertical structure of dust aerosols as well as aerosol subtypes. Promising results encourage further research and application of high-resolution modeling and satellite-based remote sensing to warn of approaching severe dust events and reduce risks for safety and health.

CASE STUDY OF ASIAN DUST EVENT ON MARCH 19-25, 2010 AND ITS IMPACT ON THE MARGINAL SEA OF CHINA

This study analyzes the most severe dust event in Taiwan in the last 20 years. The dust event occurred from March 19 to 25, 2010, with PM10 (particular matter less than 10 μm) reaching a maximum beyond 1200 μg m^(-3), and dust accounting for over 90% of the concentrations in Taiwan. The severe event originated from Mongolia on March 19, and the widespread dust moves southeastward toward Taiwan, with a thickness of 1 to 2 km near the ground. The concentrated dust layer can enhance phytoplankton bloom due to deposition of crustal nutrients, including iron. Over the marginal sea of China, the total deposition of soluble iron is estimated to be about 3926 μg m^(-2) during the event, and the chlorophyll-a concentrations over the East China Sea are enhanced by an average of approximately 0.6 mg m^(-3) and 1.5 mg m^(-3) in the first and second weeks, respectively, after the dust passage.

Simulating dry deposition fluxes of PM10 and particulate inorganic nitrogen over the eastern China seas during a severe Asian dust event using WRF-Chem model

A WRF-Chem model including a comprehensive gas-phase nitrogen chemistry module was used to simulate a severe dust event appearing in the eastern China on 19–25 March, 2002. The modeling result well reproduced PM10 concentrations in various distances from the dust sources and the transport pathway of the dust strom. The results showed that both the concentrations and the dry deposition fluxes of PM10 increased over the China seas during the dust event following the passage of a cold front system. The maximum fluxes of PM10 in the Yellow Sea and the East China Sea during the dust event were 5.5 and 8.4 times of those before the event, respectively. However, the temporal variations of the dry deposition fluxes of particulate inorganic nitrogen differed over the Yellow Sea from those over the East China Sea. Nitrate and ammonium in the whole northern China rapidly decreased because of the intrusion of dust-loaded air on 19 March. The dust plume arrived in the Yellow Sea on 20 March, decreasing the particulate inorganic nitrogen in mass concentration accordingly. The minimum dry deposition fluxes of nitrate and ammonium in the Yellow Sea were about 3/5 and 1/6 of those before the dust arrival, respectively. In contrast, when the dust plume crossed over the Yangtze Delta area, it became abundant in nitrate and ammonium and increased the concentrations and dry deposition fluxes of particulate inorganic nitrogen over the East China Sea, where the maximum dry deposition fluxes of nitrate and ammonium increased approximately by 4.1 and 2.6 times of those prior to the dust arrival.

Atmospheric forcing of the three‐dimensional distribution of dust particles over Australia: A case study

Knowledge of atmospheric processes responsible for horizontal and vertical distribution of dust particles is important for identifying their transport pathways. The Weather Research and Forecasting with Chemistry (WRF/Chem) model, complemented by observations, was used to simulate and observe the three‐dimensional distribution of Australian dust for a severe dust event during 22–23 September 2009. The passage of a cold front modified the boundary layer structure during this event, allowing dust to be lifted and subsequently transported for a significant distance. The model simulated the maximum dust concentrations to be located behind the cold front as a result of strong post‐frontal wind speeds. The boundary layer depths were also shown to be significantly deeper behind the cold front where dust particles could be lifted to the top of the boundary layer by turbulent fluxes associated with strong mixing. However, dust was predicted to reach its maximum height ahead of the cold front as a result of lifting in the warm conveyor belt. Both Moderate Resolution Imaging Spectroradiometer (MODIS) data and the WRF/Chem model results for this event highlight two transport pathways of dust: southeastward to the Tasman Sea and northward toward tropical regions of Australia. The vertical distribution of dust from Cloud‐Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite data and cross‐sectional analysis of the model results indicate that significant amounts of dust aerosols were transported over the Tasman Sea toward New Zealand within the lower atmosphere.

Factors contributing to dust storms in source regions producing the yellow-sand phenomena observed in Japan from 1993 to 2002

Asian-dust (yellow-sand) phenomena observed in Japan have been increasing in recent years, especially from 2000 to 2002. The main cause is severe dust events in arid and semi-arid regions of northeast Asia. The dust source area in northeast Asia (target area: 35°–45°N and 100°–115°E) was identified with reference to past results, and the relationship between the yellow-sand phenomena observed in Japan and dust outbreaks in the target area was examined during the springtime (March to May) from 1993 to 2002. The annual change in the number of dust phenomena observed in Japan agreed well with the Dust Storm Frequency (DSF) in the target area (R2 = 0.8796). Even though strong wind (≧7.0 m s−1) has a profound effect on dust storms (R2 = 0.515), coverage of the Normalized Differential Vegetation Index (NDVI), ranging from 0 to 0.1 (bare land with snow cover) and 0.1 to 0.2 (bare land) in April, also affected dust storms in the target area (R2 = 0.486 and 0.418).

Correlation of Asian dust with chlorophyll and primary productivity in the coastal seas of China during the period from 1998 to 2008

[1] Satellite chlorophyll a (Chl a) concentrations and estimated primary production in the coastal seas of China were correlated with Asian dust events during 1998–2008. Dust events were identified using two approaches, i.e., historical record and satellite aerosol index (AI). Severe and very severe dust events correlated well and positively with Chl a concentrations and primary production in the south Yellow Sea and East China Sea, but it was not statistically significant in the Bohai Sea and the north Yellow Sea. In the south Yellow Sea, Chl a concentration and primary production increased and eventually bloomed 1–21 days after the occurrence of the 16 out of 22 dust storms. Granger causality test showed that AI, photosynthetically available radiation (PAR) and sea surface temperature (SST) did Granger cause primary production in the Yellow Sea, suggesting that past values of the above three variables contain statistically meaningful information about current values of primary production. A stepwise multiple linear regression was used to examine the relative importance of the three factors. PAR and SST accounted for most of the variability of primary production in the north Yellow Sea, while AI was not quite as useful. In the south Yellow Sea, PAR and AI accounted for most of the variability of primary production for all storms; in addition, spring algae blooms were due to dust particles transported in the 5 km) dusts, originated mainly from the Taklimakan Desert, Mongolia, and/or west of Inner Mongolia, had no impact.

Quantification of Saharan dust contribution to PM 10 concentrations over Italy during 2003–2005

Italy is frequently affected by Saharan dust intrusions, which result in high PM 10 concentrations in the atmosphere and can cause the exceedances of the PM 10 daily limits (50 μg m −3) set by the European Union (EU/2008/50). The estimate of African dust contribution to PM 10 concentrations is therefore a key issue in air quality assessment and policy formulation. This study presents a first identification of Saharan dust outbreaks as well as an estimate of the African dust contribution to PM 10 concentrations during the period 2003–2005 over Italy. The identification of dust events has been carried out by looking at different sources of information such as monitoring network observations, satellite images, ground measurements of aerosol optical properties, dust model simulations and air mass backward trajectory analysis. The contribution of Saharan dust to PM 10 monthly concentrations has been estimated at seven Italian locations. The results are both spatially (with station) and temporally (with month and year) variable, as a consequence of the variability of the meteorological conditions. However, excluding the contribution of severe dust events (21st February 2004, 25th–28th September 2003, 23rd–27th March 2005), the monthly contribution of dust varies approximately between 1 μg m −3 and 10 μg m −3 throughout year 2005 and between 1 μg m −3 and 8 μg m −3 throughout year 2003. In 2004 the dust concentration is lower than 2003 and 2005 (<5 μg m −3 at all sites). The reduction in the number of daily exceedances of the limit value (50 μg m −3) after subtraction of the dust contribution is also calculated at each station: it varies with station between 20% and 50% in 2005 and between 5% and 25% in 2003 and 2004.

Concentrations, profiles and gas–particle partitioning of polychlorinated dibenzo- p-dioxins and dibenzofurans in the ambient air of Beijing, China

Polychlorinated dibenzo- p-dioxins (PCDDs) and furans (PCDFs) were monitored in the ambient air of Beijing, China, from February to December 2006 to evaluate their concentrations, congener profiles and gas–particle partitioning. The PCDD/F concentrations for three different districts ranged from 275 to 10,780 fg m −3, with an average of 4355 fg m −3. The I-TEQs were 18–644 fg I-TEQ m −3, with an average of 268 fg I-TEQ m −3, which was comparable or slightly higher than other urban locations around the world. Severe dust event occurred during the sampling period, on 17–19 April 2006. The levels of PCDD/Fs did not increase during the dust event (average 2489 fg m −3) compared to non-dust events (average 3671 fg m −3) although the total suspended particulates (1109 μg m −3) presented a 2.8-fold increase compared to non-dust events (392 μg m −3). The PCDD/Fs were found exclusively in the particle phase. Significant linear correlations for PCDD/Fs were observed ( R 2: 0.57–0.64) between the gas–particle partition coefficient ( K p) and the subcooled liquid vapor pressure ( P L 0 ). The Junge–Pankow model and the K oa absorption model were employed to predict the gas–particle partitioning of PCDD/F congeners. The K oa absorption model fitted well with the measurement results. However, the Junge–Pankow model slightly underestimated the particulate sorption of PCDD/Fs, which was contradicted with previous studies reported in the literature.

Mesoscale modeling of aeolian dust emission during the BoDEx 2005 experiment

The Bodélé depression (Northern Chad) is believed to be the single largest source for the Saharan dust transported over the Atlantic Ocean, especially that emerging in the Gulf of Guinea in boreal winter. During the Bodélé Dust Experiment 2005 (BoDEx 2005), which was performed in February–March 2005, a severe dust event was observed and some of its main characteristics (surface wind, dust concentrations, radiation) were recorded. This paper tests the capability of a mesoscale model coupled online with a dust production model (DPM) to reproduce the small scale features associated to this dust event. These simulations clearly show that a spatial resolution of 10 km × 10 km is required to reproduce satisfactorily the observed surface winds and the main characteristics of the dust plume.

The Relationship between Occurrence of Dust Events and Synoptic Climatological Condition in East Asia, 1999-2003

Regional differences in occurrence frequency of dust events (dust storms, sand storms and blowing dust) observed in spring (March, Apri1, and May) in 1999-2003 in the northern half of China (north of 35°N), and Mongolia are studied from the viewpoint of the relationship with strong wind and precipitation occurrence. In order to categorize the weather conditions, World Surface Data were used.Dust events are frequently observed in the regions of (I) West Tarim Basin, (II) East Tarim Basin and East Xinjiang, (III) the Hexi Corridor, (IV) southern Mongolia to Inner Mongolia, (V) a part of southern Dongbei Plain (Northeast China Plain), and (VI) the Loess Plateau. However, dust event occurrence frequency under strong wind condition, is not the same among regions and these 6 areas are divided into 2 groups as follows. In areas (I), (II), (III), and (VI), dust event frequency under strong wind conditions is high, even though the number of strong wind occurrences is small. In contrast, in areas (IV) and (V), the number of dust event occurrences is large, but the dust event frequency under strong wind conditions is low.Dust events were observed not only in arid, or semi arid region. At almost all of observatories in the study area, dust events were reported at least once in 1999-2003. However, there are areas where both the number of dust events, and dust event frequency under strong wind conditions are low, even close to arid/semi-arid land, such as Dzungaria Basin. It is attributed to high frequency of precipitation events under strong wind and land surface characteristics.We made composite maps of sea level pressure, surface air temperature, and surface wind for 10 severest “Widespread Dust Event Cluster” (WDE Clusters) by using NCEP/NCAR reanalysis data for the above 6 areas respectively. It is found that severe dust events are observed in these 6 areas on the condition that anti-cyclones develop over Kazakhstan to the Altai Mountains and western Mongolia, associated with strong cold wind over each area. In areas (I), (II), (III), and (VI), dust events occurred only under the influence of these anti-cyclones. On the other hand, in areas (IV) and (V), a clean contrast was found between these anti-cyclones and cyclones located around 47.5°N, 120°E, and the role of these cyclones seems to be important. Only in area (V), surface air temperature tends to increase at the time of the 10 strongest WDE Clusters. This is caused by southerly wind associated with the cyclone.It is suggested that the possible causes of low dust event frequencies, under strong wind condition in areas (IV) and (V), are precipitations and land surface characteristics (e.g., snow cover) caused by the cyclone development.