scholarly journals Size-segregated fluxes of mineral dust from a desert area of northern China by eddy covariance

2007 ◽  
Vol 7 (1) ◽  
pp. 2133-2168
Author(s):  
G. Fratini ◽  
P. Ciccioli ◽  
A. Febo ◽  
A. Forgione ◽  
R. Valentini
Keyword(s):  
Eddy Covariance ◽  
Mineral Dust ◽  
Northern China ◽  
Dust Particles ◽  
Storm Event ◽  
Gobi Desert ◽  
Storm Events ◽  
Particle Volume ◽  
Intense Storm ◽  
Desert Areas

Abstract. Mineral dust emission accounts for a substantial portion of particles present in the troposphere. It is emitted most from desert areas, mainly through intense storm episodes. The aim of this work was to quantify size-segregated fluxes of mineral dust particles emitted during storm events occurring in desert areas of northern China (Alashan desert, Inner Mongolia), known to act as one of the strongest sources of mineral dust particles in the Asian continent. Long-range transport of mineral dust emitted in this area is responsible for the high particle concentrations reached in densely populated areas, including the city of Beijing. Based on a theoretical analysis, an eddy covariance system was built to get size-segregated fluxes of mineral dust particles with optical diameters ranging between 0.26 and 7.00 μm. The system was optimised to measure fluxes under intense storm event conditions. It was tested in two sites located in the Chinese portion of the Gobi desert. During the field campaign, an intense storm event was recorded in one of them. Data obtained during this event indicate that particle number fluxes were dominated by the finer fraction, whereas in terms of volume, coarser particle accounted for the largest portion. It was found that during the storm event, ratios of size-segregated particle volume fluxes remained substantially constant and a simple parameterization of particle emission from total volume fluxes was possible. A strong correlation was also found between particle volume fluxes and the friction velocity. This relationship is extremely useful to investigate mechanisms of particle formation by wind erosion.

scholarly journals Size-segregated fluxes of mineral dust from a desert area of northern China by eddy covariance

2007 ◽  
Vol 7 (11) ◽  
pp. 2839-2854 ◽  
Author(s):  
G. Fratini ◽  
P. Ciccioli ◽  
A. Febo ◽  
A. Forgione ◽  
R. Valentini
Keyword(s):  
Eddy Covariance ◽  
Wind Erosion ◽  
Mineral Dust ◽  
Northern China ◽  
Particle Mass ◽  
Dust Particles ◽  
Storm Event ◽  
Mass Fluxes ◽  
Intense Storm ◽  
Desert Areas

Abstract. Mineral dust emission accounts for a substantial portion of particles present in the troposphere. It is emitted mostly from desert areas, mainly through intense storm episodes. The aim of this work was to quantify size-segregated fluxes of mineral dust particles emitted during storm events occurring in desert areas of northern China (Alashan desert, Inner Mongolia), known to act as one of the strongest sources of mineral dust particles in the Asian continent. Long-range transport of mineral dust emitted in this area is responsible for the high particle concentrations reached in densely populated areas, including the city of Beijing. Based on a theoretical analysis, an eddy covariance system was built to get size-segregated fluxes of mineral dust particles with optical diameters ranging between 0.26 and 7.00 µm. The system was optimised to measure fluxes under intense storm event conditions. It was tested in two sites located in the Chinese portion of the Gobi desert. During the field campaign, an intense wind erosion event, classified as a "weak dust storm", was recorded in one of them. Data obtained during this event indicate that particle number fluxes were dominated by the finer fraction, whereas in terms of mass, coarser particle accounted for the largest portion. It was found that during the storm event, ratios of size-segregated particle mass fluxes remained substantially constant and a simple parameterization of particle emission from total mass fluxes was possible. A strong correlation was also found between particle mass fluxes and the friction velocity. This relationship is extremely useful to investigate mechanisms of particle formation by wind erosion.

scholarly journals Simulation of heterogeneous photooxidation of SO<sub>2</sub> and NO<sub><i>x</i></sub> in the presence of Gobi Desert dust particles under ambient sunlight

2018 ◽  
Vol 18 (19) ◽  
pp. 14609-14622 ◽  
Author(s):  
Zechen Yu ◽  
Myoseon Jang
Keyword(s):  
Urban Areas ◽  
Mineral Dust ◽  
Buffering Capacity ◽  
Dust Particles ◽  
Gobi Desert ◽  
Heterogeneous Chemistry ◽  
Desert Dust ◽  
Malachite Green Dye ◽  
Photodegradation Rate ◽  
Nitrate Salts

Abstract. To improve the simulation of the heterogeneous oxidation of SO2 and NOx in the presence of authentic mineral dust particles under ambient environmental conditions, the explicit kinetic mechanisms were constructed in the Atmospheric Mineral Aerosol Reaction (AMAR) model. The formation of sulfate and nitrate was divided into three phases: the gas phase, the non-dust aqueous phase, and the dust phase. In particular, AMAR established the mechanistic role of dust chemical characteristics (e.g., photoactivation, hygroscopicity, and buffering capacity) in heterogeneous chemistry. The photoactivation kinetic process of different dust particles was built into the model by measuring the photodegradation rate constant of an impregnated surrogate (malachite green dye) on a dust filter sample (e.g., Arizona test dust – ATD – and Gobi Desert dust – GDD) using an online reflective UV–visible spectrometer. The photoactivation parameters were integrated with the heterogeneous chemistry to predict the formation of reactive oxygen species on dust surfaces. A mathematical equation for the hygroscopicity of dust particles was also included in the AMAR model to process the multiphase partitioning of trace gases and in-particle chemistry. The buffering capacity of dust, which is related to the neutralization of dust alkaline carbonates with inorganic acids, was included in the model to dynamically predict the hygroscopicity of aged dust. The AMAR model simulated the formation of sulfate and nitrate using experimental data obtained in the presence of authentic mineral dust under ambient sunlight using a large outdoor smog chamber (University of Florida Atmospheric Photochemical Outdoor Reactor, UF-APHOR). Overall, the influence of GDD on the heterogeneous chemistry was much greater than that of ATD. Based on the model analysis, GDD enhanced the sulfate formation mainly via its high photoactivation capability. In the case of NO2 oxidation, dust-phase nitrate formation is mainly regulated by the buffering capacity of dust. The measured buffering capacity of GDD was 2 times greater than that of ATD, and consequently, the maximum nitrate concentration with GDD was nearly 2 times higher than that with ATD. The model also highlights that in urban areas with high NOx concentrations, hygroscopic nitrate salts quickly form via titration of the carbonates in the dust particles, but in the presence of SO2, the nitrate salts are gradually depleted by the formation of sulfate.

scholarly journals Emission, transport, and radiative effects of mineral dust from the Taklimakan and Gobi deserts: comparison of measurements and model results

2017 ◽  
Vol 17 (3) ◽  
pp. 2401-2421 ◽  
Author(s):  
Siyu Chen ◽  
Jianping Huang ◽  
Litai Kang ◽  
Hao Wang ◽  
Xiaojun Ma ◽  
...  
Keyword(s):  
East Asia ◽  
Dust Emission ◽  
Dust Concentration ◽  
Dust Particles ◽  
Storm Event ◽  
Gobi Desert ◽  
Radiative Effects ◽  
Dust Aerosols ◽  
Budget Analysis ◽  
Westerly Jets

Abstract. The Weather Research and Forecasting Model with chemistry (WRF-Chem model) was used to investigate a typical dust storm event that occurred from 18 to 23 March 2010 and swept across almost all of China, Japan, and Korea. The spatial and temporal variations in dust aerosols and the meteorological conditions over East Asia were well reproduced by the WRF-Chem model. The simulation results were used to further investigate the details of processes related to dust emission, long-range transport, and radiative effects of dust aerosols over the Taklimakan Desert (TD) and Gobi Desert (GD). The results indicated that weather conditions, topography, and surface types in dust source regions may influence dust emission, uplift height, and transport at the regional scale. The GD was located in the warm zone in advance of the cold front in this case. Rapidly warming surface temperatures and cold air advection at high levels caused strong instability in the atmosphere, which strengthened the downward momentum transported from the middle and low troposphere and caused strong surface winds. Moreover, the GD is located in a relatively flat, high-altitude region influenced by the confluence of the northern and southern westerly jets. Therefore, the GD dust particles were easily lofted to 4 km and were the primary contributor to the dust concentration over East Asia. In the dust budget analysis, the dust emission flux over the TD was 27.2 ± 4.1 µg m−2 s−1, which was similar to that over the GD (29 ± 3.6 µg m−2 s−1). However, the transport contribution of the TD dust (up to 0.8 ton d−1) to the dust sink was much smaller than that of the GD dust (up to 3.7 ton d−1) because of the complex terrain and the prevailing wind in the TD. Notably, a small amount of the TD dust (PM2.5 dust concentration of approximately 8.7 µg m−3) was lofted to above 5 km and transported over greater distances under the influence of the westerly jets. Moreover, the direct radiative forcing induced by dust was estimated to be −3 and −7 W m−2 at the top of the atmosphere, −8 and −10 W m−2 at the surface, and +5 and +3 W m−2 in the atmosphere over the TD and GD, respectively. This study provides confidence for further understanding the climate effects of the GD dust.

Tropospheric Mineral Dust Study by High Spectral Resolution Infrared Satellite during intense dust storms

2021 ◽  
Author(s):  
Perla Alalam ◽  
Hervé Herbin
Keyword(s):  
Mineral Dust ◽  
Complex Refractive Index ◽  
Estimation Method ◽  
Dust Storms ◽  
High Spectral Resolution ◽  
Dust Particles ◽  
Physical Parameters ◽  
Chemical Compositions ◽  
Storm Events ◽  
Atmospheric Measurements

&lt;p&gt;Large desert lands such as Sahara, Gobi or Australia present main sources of atmospheric mineral dust caused by intense dust storms. Transported dust particles undergo physical and chemical changes affecting their microphysical and optical properties. This modifies their scattering and absorption properties and alters the global atmospheric radiative budget.&lt;/p&gt;&lt;p&gt;Currently, remote sensing techniques represent a powerful tool for quantitative atmospheric measurements and the only means of analyzing its evolution from local to global scale. In order to improve the knowledge of atmospheric aerosol distributions, many efforts were made particularly in the development of hyperspectral infrared spectrometers and processing algorithms. However, to fully exploit these measurements, a perfect knowledge of Complex Refractive Index (CRI) is required.&lt;/p&gt;&lt;p&gt;In that purpose, a new methodology&amp;#160;&lt;sup&gt;&lt;/sup&gt;based on laboratory measurements of mineral dust in suspension coupled with an optimal estimation method has been developed. This approach allows getting access to CRI of several desert samples with various chemical compositions.&lt;/p&gt;&lt;p&gt;Here, we present the first results of the physical parameters (effective radius and concentration) retrievals using Infrared Atmospheric Sounding Interferometer IASI data, during dust storm events. The latter use the CRI of different desert samples obtained in laboratory and a new radiative transfer algorithm (ARAHMIS) developed at Laboratoire d&amp;#8217;Optique Atmosph&amp;#233;rique LOA.&lt;/p&gt;

scholarly journals Investigation of severe dust storms over the Pan-Eurasian area using multi-satellite observations and ground-based measurements

2018 ◽  
Author(s):  
Lu She ◽  
Yong Xue ◽  
Jie Guang ◽  
Yahui Che ◽  
Cheng Fan ◽  
...  
Keyword(s):  
Air Quality ◽  
Dust Storm ◽  
Northern China ◽  
Dust Storms ◽  
Satellite Observations ◽  
Central China ◽  
Dust Particles ◽  
Gobi Desert ◽  
Long Distance ◽  
Hysplit Model

Abstract. The deserts in East Asia are one of the most influential mineral dust source regions in the world. Large amounts of dust particles are emitted and transported to distant regions. A super dust storm characterized by long-distance transport occurred over the Pan-Eurasian Experiment (PEEX) area in early May 2017. In this study, multi-satellite/sensor observations and ground-based measurements combined with the HYbrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model were used to analyse the dynamical processes of the origin and transport of the strong dust storm. The optical and microphysical properties of the dust particles were analysed using Aerosol Robotic Network (AERONET) measurements. From the multi-satellite observations, the dust storms were suggested to have originated from the Gobi Desert on the morning of 3 May 2017, and it transported dust northeastward to the Bering Sea, eastward to the Korean Peninsula and Japan, and southward to southern Central China. The air quality in China drastically deteriorated as a result of this heavy dust storm; the PM10 (particulate matter less than 10 mm in aerodynamic diameter) concentrations measured at some air quality stations located in northern China reached 4000 μg/m3. During the dust event, the maximum AOD values reached 3, 2.3, 2.8, and 0.65 with sharp drops in the extinction Ångström exponent (EAE) to 0.023, 0.068, 0.03, and 0.097 at AOE_Baotou, Beijing, Xuzhou-CUMT, and Ussuriysk, respectively. The dust storm introduced great variations in the aerosol property, causing totally different spectral single-scattering albedo (SSA) and volume size distribution (VSD). The combined observations revealed comprehensive information about the dynamic transport of dust and the dust affected regions, and the effect of dust storms on the aerosol properties.

scholarly journals Emission, transport and radiative effects of mineral dust from Taklimakan and Gobi Deserts: comparison of measurements and model results

2016 ◽  
Author(s):  
Siyu Chen ◽  
Jianping Huang ◽  
Litai Kang ◽  
Hao Wang ◽  
Xiaojun Ma ◽  
...  
Keyword(s):  
East Asia ◽  
Dust Emission ◽  
Dust Concentration ◽  
Dust Particles ◽  
Storm Event ◽  
Gobi Desert ◽  
Radiative Effects ◽  
Climate Effect ◽  
Dust Aerosols ◽  
Westerly Jets

Abstract. The weather research and forecasting model with chemistry (WRF-Chem) was used to investigate a typical dust storm event that occurred from 18th to 23rd March 2010 and swept across almost all of China, Japan, and Korea. WRF-Chem captured the spatial and temporal variations in dust aerosols and the meteorological conditions over East Asia well, and the results were used to further investigate details of processes related to dust emission, long-range transport, and radiative effects of dust aerosols over the Taklimakan desert (TD) and Gobi desert (GD). Results showed that the differences of weather conditions and topography and surface types in dust source regions may lead to the differences of dust emission, uplift height and transport. The typical dust event over East Asia was classified into two main stages. In the first stage (18th–20th March), the GD was located in the warm zone in advance of a cold front. The enhanced convection increased momentum transfer in the middle and lower troposphere because of the instability in the atmosphere. Moreover, the GD is located in relatively flat, high altitude regions influenced by the confluence of the northern and southern westerly jets. Therefore, the GD dust transport was the primary contributor to the dust concentration over East Asia. The strength of the dust emission decreased greatly during the second stage (21st–23rd March). The TD dust emission contributed to the dust concentration over East Asia. Cold air was lifted over the Pamir Plateau and intruded into the Tarim basin causing a strong uplifting motion. The average TD dust emission flux was 27.2 ± 4.1 μg m−2 s−1. However, the transport contribution of the TD dust (1.1 ton day−1) to the dust sink was smaller than that of the GD dust (1.4 ton day−1) because of the complex terrain and the prevailing wind in the TD. It is noted that the TD is not the main source region in China but a small amount of the TD dust was lofted to more than 5 km and transported over greater distances under the influence of the westerly jets. Moreover, the radiative forcing induced by dust particles is estimated as −3 W m−2 and −7 W m−2 at the top of the atmosphere, −8 W m−2 and −10 W m−2 at the surface, and +5 W m−2 and +3 W m−2 in the atmosphere over the TD and GD, respectively. The study provided confidence for further understanding the climate effect of the TD and GD dust.

scholarly journals Simulation of Heterogeneous Photooxidation of SO<sub>2</sub> and NO<sub>x</sub> in the presence of Gobi Desert Dust Particles under Ambient Sunlight

2018 ◽  
Author(s):  
Zechen Yu ◽  
Myoseon Jang
Keyword(s):  
Urban Areas ◽  
Mineral Dust ◽  
Kinetic Mechanism ◽  
Buffering Capacity ◽  
Dust Particles ◽  
Gobi Desert ◽  
Heterogeneous Chemistry ◽  
Desert Dust ◽  
Photodegradation Rate ◽  
Nitrate Salts

Abstract. To improve the simulation of the heterogeneous oxidation of SO2 and NOx in the presence of authentic mineral dust particles under ambient environmental conditions, the explicit kinetic mechanism was constructed in Atmospheric Mineral Aerosol Reaction (AMAR) model. The formation of sulfate and nitrate was divided into three phases: gas phase, non-dust aqueous phase and dust phase. Specially, AMAR established the mechanistic role of dust chemical characteristics (e.g., photoactivation, hygroscopicity, and buffering capacity) on heterogeneous chemistry. The photo-activation kinetic process of different dust particles was built into the model by measuring the photodegradation rate constant of an impregnated surrogate (malachite green dye) on a dust filter sample (e.g., Arizona Test dust (ATD) and Gobi Desert dust (GDD)) using an online reflective UV-visible spectrometer. The photoactivation parameters were integrated with the heterogeneous chemistry to predict OH radical formation on dust surfaces. A mathematical equation for the hygroscopicity of dust particles was also included in the AMAR model to process the multiphase partitioning of tracers and in-particle chemistry. The buffering capacity of dust, which is related to the neutralization of dust alkaline carbonates with inorganic acids, was included in the model to dynamically predict the hygroscopicity of aged dust. The AMAR model simulated the formation of sulfate and nitrate using experimental data obtained in the presence of authentic mineral dust under ambient sunlight using a large outdoor smog chamber (UF-APHOR). Overall, both GDD and ATD significantly enhanced the formation of sulfate and nitrate, compared to that in the system without dust particles. However, the influence of GDD on the heterogeneous chemistry was much greater than that of ATD. Based on the model analysis, GDD enhanced the sulfate formation mainly via its high photoactivation capability. In the case of NO2 oxidation, dust-phase nitrate formation is mainly regulated by the buffering capacity of dust. The measured buffering capacity of GDD was two times greater than that of ATD, and consequently, the maximum nitrate concentration with GDD was nearly two times higher than that with ATD. The model also highlights that in urban areas with high NOx concentrations, hygroscopic nitrate salts quickly form via titration of the carbonates in the dust phase, but in the presence of SO2, the nitrate salts are gradually depleted by sulfate.

scholarly journals Observation of nitrate coatings on atmospheric mineral dust particles

2009 ◽  
Vol 9 (6) ◽  
pp. 1863-1871 ◽  
Author(s):  
W. J. Li ◽  
L. Y. Shao
Keyword(s):  
Mineral Dust ◽  
Cloud Condensation Nuclei ◽  
Northern China ◽  
Heterogeneous Reactions ◽  
Dust Particles ◽  
Sample Collection ◽  
Mineral Particles ◽  
Hygroscopic Properties ◽  
Cooling Effects ◽  
Ccn Activity

Abstract. Nitrate compounds have received much attention because of their ability to alter the hygroscopic properties and cloud condensation nuclei (CCN) activity of mineral dust particles in the atmosphere. However, very little is known about specific characteristics of ambient nitrate-coated mineral particles on an individual particle scale. In this study, sample collection was conducted during brown haze and dust episodes between 24 May and 21 June 2007 in Beijing, northern China. Sizes, morphologies, and compositions of 332 mineral dust particles together with their coatings were analyzed using transmission electron microscopy (TEM) coupled with energy-dispersive X-ray (EDX) microanalyses. Structures of some mineral particles were verified using selected-area electron diffraction (SAED). TEM observation indicates that approximately 90% of the collected mineral particles are covered by visible coatings in haze samples whereas only 5% are coated in the dust sample. 92% of the analyzed mineral particles are covered with Ca-, Mg-, and Na-rich coatings, and 8% are associated with K- and S-rich coatings. The majority of coatings contain Ca, Mg, O, and N with minor amounts of S and Cl, suggesting that they are possibly nitrates mixed with small amounts of sulfates and chlorides. These nitrate coatings are strongly correlated with the presence of alkaline mineral components (e.g., calcite and dolomite). CaSO4 particles with diameters from 10 to 500 nm were also detected in the coatings including Ca(NO3)2 and Mg(NO3)2. Our results indicate that mineral particles in brown haze episodes were involved in atmospheric heterogeneous reactions with two or more acidic gases (e.g., SO2, NO2, HCl, and HNO3). Mineral particles that acquire hygroscopic nitrate coatings tend to be more spherical and larger, enhancing their light scattering and CCN activity, both of which have cooling effects on the climate.

scholarly journals Simulation of an Asian Dust Storm Event in May 2017

Atmosphere ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 135 ◽  
Author(s):  
Ping Song ◽  
Jianfang Fei ◽  
Changshun Li ◽  
Xiaogang Huang
Keyword(s):  
Size Distribution ◽  
Dust Storm ◽  
Source Region ◽  
Dust Emission ◽  
Northern China ◽  
Dust Particles ◽  
Storm Event ◽  
Dust Size Distribution ◽  
Dust Storm Event ◽  
Local Dust

Dust particles in the atmosphere play an important role in air pollution, climate change, and biogeochemical cycles. Some of the dominant sources of dust in mid-latitude regions are in Asia. An intense dust storm engulfed Northern China at the beginning of May 2017, and PM10 mass concentrations of 1500–2000 μg m−3 were measured near the dust source region. We combined numerical simulations, air quality monitoring data, and satellite retrievals to investigate dust emission and transport during this event. We found that the event was closely related to cold front activity, characterized by increased wind speed, which increased dust emission. We improved the dust scheme using a local dust size distribution to better simulate the dust emission flux. We found that accurate parametrization of the dust size distribution was important to effectively simulate both dust emission and ambient particle concentration. We showed that using a local dust size distribution substantially improved the accuracy of the simulation, allowing both the spatial distribution of pollution caused by the dust storm and temporal variability in the pollution to be captured.

scholarly journals Understanding of Storm Runoff Generation in a Weathered, Fractured Granitoid Headwater Catchment in Northern China

Water ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 123 ◽  
Author(s):  
Sihan Zhao ◽  
Hongchang Hu ◽  
Ciaran Harman ◽  
Fuqiang Tian ◽  
Qiang Tie ◽  
...  
Keyword(s):  
Potential Evapotranspiration ◽  
Stream Water ◽  
Fractured Rock ◽  
Northern China ◽  
Storm Event ◽  
Hydrograph Separation ◽  
Storm Events ◽  
Stable Water Isotopes ◽  
Runoff Generation ◽  
Streamflow Generation

Few of the classical field studies of streamflow generation in headwater watersheds have been conducted in catchments with thin soils and deeply weathered crystalline silicate bedrock. As such, the role of the (potentially very large) storage capacity of weathered, fractured rock in baseflow and storm event discharge remains poorly characterized. Here we present a study of streamflow generation in an upland semi-humid watershed (Xitaizi Experimental Watershed, XEW, 4.22 km2) dominated by baseflow feeding one of the main water supply reservoirs for the city of Beijing, China. This catchment is relatively dry (625 mm/yr precipitation, 480 mm/yr Evapotranspiration), but has strongly seasonal precipitation that varies in phase with strongly seasonal potential evapotranspiration. The catchment was instrumented with four weather stations and precipitation collectors, 11 deep wells drilled into the bedrock along three hillslopes, and additional soil moisture sensors and water samplers along one hillslope. In six storm events over two years, samples of rainfall, soil water (10–80 cm depth), groundwater, and stream water were collected with high frequency and analyzed for stable water isotopes (δ18O and δ2H). Tracer-based hydrograph separation showed that event water (precipitation) makes up the majority of the hydrograph peak above baseflow, and pre-event water contributions (on average) simply represent the steady release of groundwater. The quantity of event water corresponded to a very small effective contributing area (<0.2% of the catchment) that nevertheless showed a clear dependence on catchment wetness as measured by the streamflow. The streamflow itself was isotopically identical to the deep groundwater in wells. This suggests that the fractured, weathered, bedrock system dominates the production of streamflow in this catchment.

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