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Deserts are ideal places to build photovoltaic (PV) power plants, but this plants often face challenges from strong wind and sand activities during the operation and maintenance period, exploring the effects of PV power plant construction on wind disturbances and the control of wind and sand activities by different sand fixation measures is necessary. This study investigated the wind speed outside the PV plant, inside the plant without sand barriers measures (CK), and under three different sand-protecting barriers (gauze sand barriers (GZ), polylactic acid sand barriers (PLA), and grass grid sand barriers (GG)) inside the plant. Though calculated the surface roughness, friction velocity, wind protection effectiveness, and wind turbulence to determined the effectiveness of the barriers by these indexes comprehensively. The results show that: (1) The construction of desert PV power plant can effectively reduce the wind speed. Compared with CK, all three mechanical sand barriers within the plant reduced wind speed. Especially when the height less than 50cm, the GZ sand barriers reduced the wind speeds the most, with an average reduction rate of 101.5%. (2) All three sand barriers increased soil roughness and friction velocity within the power station. (3) At heights below 50cm, the GZ and GG sand barriers have better wind protection effectiveness than PLA sand barriers, while at hights above 100cm, the wind protection effect of PLA and GG sand barriers became less significant or even negligible (4) The wind disturbance caused by the three sand fixation measures increased with wind speed, the comprehensive performance of GZ and PLA sand barriers was superior than that of GG sand barriers and CK. [ABSTRACT FROM AUTHOR]

Sandstorms pose a substantial hurdle to image clearness, affecting visibility, detail representation, and color quality. In this study, a novel algorithm named multistep color reparation (MCR) is constructed, particularly for the enhancement of images impacted by sandstorms. MCR includes a thorough procedure comprising five distinct phases. The first phase focuses on enhancing color indemnity by effectively compensating the missing color information, assuring that the enhanced images appear with better true-to-life colors. Next, a statistics-based intensity redistribution is employed as a second phase to emphasize tonality, ensuring better perceptual quality. The third phase applies an optimized intuitionistic fuzzy model, leveraging the fuzzy model's undiscovered abilities to remove the dust veil. Following this, a color deviation correction phase is executed to rectify the emerging color shifts and inaccuracies, applying corrective measures to enliven accurate color representation. Finally, a fast visibility restoration approach is implemented to improve the visibility and provide better saturation. To evaluate the efficacy of MCR, thorough experiments were performed comparing it with eight state-of-the-art algorithms. Quality assessments were carried out using six high-level image evaluation metrics alongside the processing times. The findings exhibited that MCR outperforms all competing algorithms, and it efficaciously addressed the challenges posed by sandstorm-induced degradation, presenting substantial enhancements in perceptual fidelity and quality. [ABSTRACT FROM AUTHOR]

Abstract Alxa League, located in the western part of Inner Mongolia, China, frequently suffers from sandstorms. Such dusty conditions result in sharp increases in respirable particulate matter (PM10) concentration in outdoor and indoor environments, posing a significant health risk to local inhabitants. Vernacular dwellings in this area feature a specific floor plan that includes an entrance space to safeguard indoor air quality during sandstorms while being compatible with the local climate. This study utilises CONTAM, a multizone indoor air quality and ventilation analysis computer program, and field measurements to quantitatively evaluate the effectiveness of the entrance space in protecting indoor air quality against ambient PM10 pollution under both dusty and normal conditions. The simulation results reveal that the entrance space can effectively mitigate PM10 pollution in the middle room, lowering the average concentration from 47.0 μg/m3 to 37.5 μg/m3 during dust periods. However, PM10 pollution may increase in the entrance space, reaching an average concentration of up to 70.0 μg/m3. Experimental outcomes align with the simulated results. Given that construction activities exacerbate desertification and frequent sandstorms, the above findings help identify the optimal design strategies for energy-efficient green vernacular dwellings in the targeted desert area, promoting environmental harmony and addressing climate change challenges.

• In Beijing's super sandstorm 2021, 5700 amplicon sequence variants were detected. • Airborne bacteria in sandstorms were compared with the after-storm and haze days. • The sandstorm newly brought 10 pathogenic bacterial genera to the atmosphere. • Small bioaerosols (0.65–1.1 µm) were still suspended after the sandstorm subsided. Sandstorm, which injects generous newly emerging microbes into the atmosphere covering cities, adversely affects the air quality in built environments. However, few studies have examined the change of airborne bacteria during severe sandstorm events. In this work, we analyzed the airborne bacteria during one of the strongest sandstorms in East Asia on March 15th, 2021, which affected large areas of China and Mongolia. The characteristics of the sandstorm were compared with those of the subsequent clean and haze days. The composition of the bacterial community of air samples was investigated using quantitative polymerase chain reaction (qPCR) and high-throughput sequencing technology. During the sandstorm, the particulate matter (PM) concentration and bacterial richness were extremely high (PM 2.5 : 207 µg/m3; PM 10 : 1630 µg/m3; 5700 amplicon sequence variants/m3). In addition, the sandstorm brought 10 pathogenic bacterial genera to the atmosphere, posing a grave hazard to human health. As the sandstorm subsided, small bioaerosols (0.65–1.1 µm) with a similar bacterial community remained suspended in the atmosphere, bringing possible long-lasting health risks. [Display omitted] [ABSTRACT FROM AUTHOR]

Alxa League, located in the western part of Inner Mongolia, China, frequently suffers from sandstorms. Such dusty conditions result in sharp increases in respirable particulate matter (PM10) concentration in outdoor and indoor environments, posing a significant health risk to local inhabitants. Vernacular dwellings in this area feature a specific floor plan that includes an entrance space to safeguard indoor air quality during sandstorms while being compatible with the local climate. This study utilises CONTAM, a multizone indoor air quality and ventilation analysis computer program, and field measurements to quantitatively evaluate the effectiveness of the entrance space in protecting indoor air quality against ambient PM10 pollution under both dusty and normal conditions. The simulation results reveal that the entrance space can effectively mitigate PM10 pollution in the middle room, lowering the average concentration from 47.0 μg/m3 to 37.5 μg/m3 during dust periods. However, PM10 pollution may increase in the entrance space, reaching an average concentration of up to 70.0 μg/m3. Experimental outcomes align with the simulated results. Given that construction activities exacerbate desertification and frequent sandstorms, the above findings help identify the optimal design strategies for energy-efficient green vernacular dwellings in the targeted desert area, promoting environmental harmony and addressing climate change challenges. [ABSTRACT FROM AUTHOR]

Deserts are ideal places to build photovoltaic (PV) power plants, but this plants often face challenges from strong wind and sand activities during the operation and maintenance period, exploring the effects of PV power plant construction on wind disturbances and the control of wind and sand activities by different sand fixation measures is necessary. This study investigated the wind speed outside the PV plant, inside the plant without sand barriers measures (CK), and under three different sand-protecting barriers (gauze sand barriers (GZ), polylactic acid sand barriers (PLA), and grass grid sand barriers (GG)) inside the plant. Though calculated the surface roughness, friction velocity, wind protection effectiveness, and wind turbulence to determined the effectiveness of the barriers by these indexes comprehensively. The results show that: (1) The construction of desert PV power plant can effectively reduce the wind speed. Compared with CK, all three mechanical sand barriers within the plant reduced wind speed. Especially when the height less than 50cm, the GZ sand barriers reduced the wind speeds the most, with an average reduction rate of 101.5%. (2) All three sand barriers increased soil roughness and friction velocity within the power station. (3) At heights below 50cm, the GZ and GG sand barriers have better wind protection effectiveness than PLA sand barriers, while at hights above 100cm, the wind protection effect of PLA and GG sand barriers became less significant or even negligible (4) The wind disturbance caused by the three sand fixation measures increased with wind speed, the comprehensive performance of GZ and PLA sand barriers was superior than that of GG sand barriers and CK.

Aerosols influence cloud microphysical properties by acting as cloud condensation nuclei and ice nuclei. Aerosols have the potential to modify the location and intensity of precipitation by changing cloud properties. However, identifying precipitation changes induced by aerosols remains a significant challenge for current research. Dust aerosol carried by dust storms is an important source of ice nuclei. China and Mongolia are the primary desert regions in Asia and the world. The Mongolian cyclone in northern China is one of the significant weather systems that cause sandstorms in both countries. Studying the impact of dust aerosols on clouds under the weather conditions of Mongolian cyclones and sandstorms is of great significance. Due to challenges of aerial observations during dust storms, the impact of dust aerosols on clouds is minimally understood during Mongolian cyclone dust storms. In order to investigate the impact of dust aerosols on clouds, a study is conducted based on the comprehensive observation experiment of clouds in Beijing Area carried out by Beijing Weather Modification Center. An extremely rare case of strong sandstorm weather caused by a Mongolian cyclone and cold front is observed on 24 April 2009. The vertical macro and micro physical structure characteristics of dust cloud and clean cloud are compared and analyzed, and the potential influence of dust aerosols on clouds is discussed. Results show that dust aerosol transferred from China-Mongolia areas is an important source of ice nuclei in North China. It can be transferred vertically to a height of 3200 meters above the cloud top. The concentration of ice nuclei in the dust background area is significantly increased by 10 times compared to that in the clean background area. This increase further affects the microphysical structure of cumulus and stratocumulus clouds with high cloud top temperatures (-6 ℃ to -3 ℃) by altering the process of ice crystal formation. At the same temperature, the average concentration of ice crystals in the dust cloud increases significantly by nearly 10 times compared to that in the clean cloud. The liquid water content is reduced, leading to the formation of a large number of small ice crystal particles in the cloud. It inhibits the rime process and results in a significant reduction in the average concentration of precipitation particles compared to that in the clean cloud. Additionally, the spectral width of cloud droplets, ice and snow crystals, and precipitation particles is significantly narrower than that in the clean cloud. It will eventually weaken the precipitation, which will have a significant impact on the weather and climate in North China. It is helpful to enhance our understanding of the indirect effects of aerosols.

Copyright of Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wind-sand flow generates erosion and deposition around obstacles such as bridges and roadbeds, resulting in sand damage and endangering railway systems in sandy regions. Previous studies have mainly focused on the flow field around roadbeds, overlooking detailed examinations of sand particle erosion and deposition patterns near bridges and roadbeds. This study employs numerical simulations to analyze the influence of varying heights and wind speeds on sand deposition and erosion characteristics at different locations: the bridge-road transition section (side piers), middle piers, and roadbeds. The results show that the side piers, experience greater accumulation than the middle piers. Similarly, the leeward side of the roadbed witnesses more deposition compared to the windward side. Another finding reveals a reduced sand deposition length as the vertical profile, in alignment with the wind direction, moves further from the bridge abutments at the same clearance height. As wind speeds rise, there's a decline in sand deposition and a marked increase in erosion around the side piers, middle piers and roadbeds. In conclusion, a bridge clearance that's too low can cause intense sand damage near the side piers, while an extremely high roadbed may lead to extensive surface sand deposition. Hence, railway bridges in areas prone to sandy winds should strike a balance in clearance height. This research provides valuable guidelines for determining the most suitable bridge and roadbed heights in regions affected by wind and sand. [ABSTRACT FROM AUTHOR]

Dust events frequently occur in Tarim Basin (TB), China. However, research is scarce on the variation characteristics of sand-dust, floating-dust, sand-blowing, and sandstorms in the mountains, oases, and deserts in TB. Therefore, we conducted in-depth studies on the distributions and variations of dust events in TB. The results indicate that dust events tend to increase from south to north. The yearly sand-dust event occurrence rate trend is deserts > oases > mountainous regions. Spring events of sand-dust, floating-dust, sand-blowing, and sandstorms account for 35.9%, 36.0%, 38.5%, and 47.1% and summer events for 33.6%, 33.5%, 43.8%, and 60.3% of the total annual average sand-dust, floating-dust, sand-blowing, and sandstorm days, respectively. From 1961 to 2015, most stations (annual average > 30 stations) showed a downward linear trend in sand-dust, floating-dust, sand-blowing, and sandstorms in TB. All types of sand-dust events in mountains and oases decreased substantially after 1975–1978. In spring and summer, the downward dust trends are the most obvious, which the largest annual average downward linear trend rates of floating-dust, sand-blowing, and sandstorms are − 0.33 d/yr (QM station), − 0.21 d/yr (TGLK station), and − 11 d/yr (KP station), respectively, in spring, and − 0.28 d/yr (QM station), − 0.17 d/yr (TGLK station), and − 0.14 d/yr (KP station), respectively, in summer. It is found that the decreasing and increasing trends of floating-dust are the most frequent among sand-dust events. There are a significant positive correlation between wind speed and relative humidity in mountains and a significant positive correlation between wind speed in oases. [ABSTRACT FROM AUTHOR]

Copyright of Arid Land Geography is the property of Chinese Academy of Sciences, Xinjiang Institute of Ecology & Geography and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

According to field observations, the atmospheric boundary layer is usually unstably stratified before a dust and sandstorm, the particle-laden turbulent gravity current with an extremely high Reynolds number. In this paper, an inviscid model was built to study the mechanism governing the slumping phase of gravity current. It is shown that the dimensionless current front speed, the Froude number, decreases when the current fluid or the ambient medium or both fluids are unstably stratified. In spite of the density interface mixing, the relation between the front speed and the front height described by the inviscid model agrees with the numerical simulation results, where the lock-exchange gravity currents with different initial lock heights were calculated for different unstable stratification cases. Furthermore, the velocity increments obtained by field observations at the sandstorm fronts are satisfactorily consistent with the evaluations of the model, suggesting that the inviscid mechanism makes contribution to such high Reynolds number turbulent flows.

This article, published in the Qatar Medical Journal, explores the rare inherited disorder known as pulmonary alveolar microlithiasis (PAM). The article presents four cases of PAM reported in Qatar, including a 16-year-old male who presented with sudden chest pain and a 38-year-old Yemeni woman with sore throat and fever. The article describes the diagnostic process, which involves chest X-rays, CT scans, and bronchoscopy with biopsy. The authors conclude that PAM typically progresses slowly and is often diagnosed incidentally through chest X-rays. [Extracted from the article]

Sandstorm, as a disastrous weather phenomenon, seriously threatens the ecological environment and human health. In this study, the normalized brightness temperature dust index (NBTDI) data set of sandstorms in Yellow River Basin, China during 2000–2021 was constructed. Based on this, the temporal and spatial distribution pattern of sandstorms in the Yellow River Basin in the 21st century was analyzed. The variation trend of NBTDI in the past 22 years was discussed. The results showed that the interannual variation of sandstorms in the 21st century weakened first and then intensified. From the perspective of seasonal variation, sandstorm events occurred most frequently in spring (92.4%), followed by winter (5.6%), and occasionally in summer and autumn. In space, the distribution of sandstorms in the Yellow River Basin had obvious spatial heterogeneity. The central location of the sandstorm in the Yellow River Basin moved slightly to the north, but all of them were concentrated on desert areas. This was caused by the combination of unique geographical location and meteorological factors. The natural climate was closely related to the occurrence of sandstorms. The variation trend of long time-series NBTDI indicated that there were long memories between 22 years of sandstorms. NBTDI had an increasing trend in the long time series. In the future, sandstorms will become more frequent, in line with past trends. This study provides important data support for comprehensive understanding of extreme sandstorm weather, and has important significance for large-scale and long-term monitoring of sandstorm weather.

Extreme meteorological events can influence air quality. In March 2021, northern China experienced a severe dust event, leading to widespread air quality deterioration. Using reanalysis datasets and station data, we investigate the synoptic weather patterns, dust transport characteristics, and associated impacts on air quality during this event. The results are as follows. (1) The dust event is closely linked to the Mongolian cyclone, providing favorable conditions for dust emission and long-distance transport. (2) The Gobi Desert in Mongolia is the primary source, with dust particles transported from Mongolia to northern China via the northwesterly flow. Dust transport exhibits a complex three-dimensional structure, with the most intense dust transport at approximately 2500 m altitude. (3) The impact of this dust event on air quality was characterized by its remarkable intensity, extensive spatial coverage, and prolonged duration. Additionally, 58.8% of the stations in northern China experienced pollution, 36.3% of them reached severe pollution levels or higher, and 35.9% of the sites experienced more than 12 h of pollution. (4) The visibility at the northern stations near the dust source rapidly decreases due to solid dust particles. In contrast, the southern stations, with higher moisture content, are primarily affected by liquid particles in terms of visibility. After the frontal passage, wet deposition from the precipitation process gradually improves visibility. [ABSTRACT FROM AUTHOR]

Desert dust and sandstorms are recurring environmental phenomena that are reported to produce serious health risks worldwide. This scoping review was conducted to identify the most likely health effects of desert dust and sandstorms and the methods used to characterize desert dust exposure from the existing epidemiological literature. We systematically searched PubMed/MEDLINE, Web of Science, and Scopus to identify studies that reported the effects of desert dust and sandstorms on human health. Search terms referred to desert dust or sandstorm exposure, names of major deserts, and health outcomes. Health effects were cross‐tabulated with study design variables (e.g., epidemiological design and methods to quantify dust exposure), desert dust source, health outcomes and conditions. We identified 204 studies that met the inclusion criteria for the scoping review. More than half of the studies (52.9%) used a time‐series study design. However, we found a substantial variation in the methods used to identify and quantify desert dust exposure. The binary metric of dust exposure was more frequently used than the continuous metric for all desert dust source locations. Most studies (84.8%) reported significant associations between desert dust and adverse health effects, mainly for respiratory and cardiovascular mortality and morbidity causes. Although there is a large body of evidence on the health effects of desert dust and sandstorms, the existing epidemiological studies have significant limitations related to exposure measurement and statistical analysis that potentially contribute to inconsistencies in determining the effect of desert dust on human health. Plain Language Summary: Desert dust and dust storms are recurring environmental phenomena and have been reported to cause serious health hazards worldwide. A scoping review was conducted of the existing epidemiological literature to identify and categorize the methods used to characterize desert dust exposure and the most likely health effects of desert dust and dust storms. We identified 204 studies that met the inclusion criteria for the scoping review. More than half (52.9%) of the studies employed time series and case‐crossover study designs; 84.8% reported a significant association between desert dust and adverse health outcomes. Although most studies reported adverse health effects, existing studies have significant limitations in exposure measurement and statistical analysis, which may lead to inconsistencies in determining the health effects of desert dust. Key Points: Desert dust and sandstorms are recurring environmental phenomena that are reported to produce serious health risks worldwideInconsistencies in exposure definitions and modeling strategies may have contributed to the observed heterogeneity in the effect estimatesDeveloping a standardized research protocol could be a vital step toward better assessing the association between desert dust and health [ABSTRACT FROM AUTHOR]

Sandstorm is a disastrous weather phenomenon that often occurs in arid and semi-arid areas, endangering the ecological environment and affecting people's lives and property safety seriously. Since the 21st century, the sandstorm weather in the Yellow River Basin has ameliorated obviously. However, the causes of the long-term trends in sandstorms during 21st century were still unknown. In this study, fifteen influencing factors from five aspects: ecology, meteorology, hydrology, geography and man-made were selected to comprehensively analyze the driving mechanism of sandstorm activities in the Yellow River Basin since the 21st century, and the effect of each influencing factor on sandstorm weather was quantified. The results indicated that ecological, meteorological and geographical factors had dominant impacts on the spatio-temporal variation of sandstorms during 2000–2021, while hydrological and human factors played little role in the long-term variation of sandstorms. Sandstorms frequently occurred in semi-desert or grassland or non-high vegetation covered areas in spring. Vegetation coverage, precipitation, surface pressure, surface roughness, and soil moisture content were negatively correlated with sandstorms, while wind speed, friction velocity, evaporation, and soil temperature were positively correlated with sandstorms. Precipitation, runoff, evaporation, soil moisture content, soil temperature, and surface temperature indirectly acted on normalized brightness temperature dust index (NBTDI) and sandstorms by changing soil texture. Normalized Vegetation Index (NDVI) had direct negative effects on NBTDI, while wind speed 10 m (WS10m), slope of sub-gridscale orography (SOSGO), and forecast surface roughness (FSR) had direct positive effects on NBTDI. This study comprehensively revealed the dominant factors and their driving mechanism of sandstorm weather in the Yellow River Basin since the 21st century, which had practical application value for the prevention of sandstorms. [Display omitted] • Spatial heterogeneity existed in sandstorms drives across different regions during 2000–2021. • Precipitation, runoff, evaporation, soil moisture, and temperature indirectly affect sandstorms through soil texture. • SP, NDVI, ST, E, R and WS10m on the long-term change of sandstorm were more important. • Vegetation, evaporation, runoff, slope negatively affect sandstorms; wind, temperature positively. [ABSTRACT FROM AUTHOR]

The short-, medium- and long-chain chlorinated paraffins (SCCPs, MCCPs, and LCCPs) were measured in outdoor fine particulate matter (PM 2.5) and gas-phases in Xi'an in spring, autumn and winter of 2021, which containing two special events during this time, the sandstorms happened in spring and the COVID-19 epidemic in winter. The CPs concentrations in PM 2.5 were seasonal variated, with spring (mean: 17.5 ng/m3) > autumn (mean: 8.6 ng/m3) > winter (mean: 5.8 ng/m3). The CPs concentrations in gas phases (mean:12.6 ng/m3) were lower than in PM 2.5 in spring, and it showed shorter carbon chain and lower chlorinated CPs dominated in SCCPs in gas phase (C 10 , Cl 5,6) compared with in PM 2.5 (C 11 , Cl 6,7). The absorption was the main mechanism for the partitioning of CP in particle and gaseous phase. The shorter carbon chain CPs (C 10,11 , C 14) with lower chlorinated (Cl 6,7) CPs dominated in SCCPs and MCCPs, while the longer carbon chain (C 25 or C 29) with Cl 6,12 dominated in the LCCPs. So, more researches about the LCCPs should be concerned. Additionally, the CPs concentrations of all samples during the sandstorms in spring were increased 30.4%–136.5% and the proportion of SCCPs was obviously elevated. CPs concentrations obviously decreased during the COVID-19 epidemic in winter, while SCCPs, MCCPs attributed comparable in autumn and winter. Potential source analysis showed that during the sandstorms in spring, atmospheric pollutants were mainly transported over a long distance from northern and northeast of Shaanxi Province, while it was mainly from local emission during the COVID-19 epidemic in winter. The health risk assessment of CPs displayed that there had no or very low inhalation exposure risks of CPs for all age groups, but the younger age groups (younger than 6 years old) should be played more attention for their not fully development of their immune and respiratory systems. [Display omitted] • The sandstorms greatly elevated the chlorinated paraffins levels, especially SCCPs. • CPs decreased in COVID-19 epidemic, with similar compositions as usual. • Shorter-chain and lower chlorinated CPs dominated in gas phase compare to PM 2.5. • The longer carbon chain CPs dominated in the LCCPs, unlike SCCPs and MCCPs. • Absorption mechanism had an important role in atmospheric partitioning of CPs. [ABSTRACT FROM AUTHOR]

Abstract Desert dust and sandstorms are recurring environmental phenomena that are reported to produce serious health risks worldwide. This scoping review was conducted to identify the most likely health effects of desert dust and sandstorms and the methods used to characterize desert dust exposure from the existing epidemiological literature. We systematically searched PubMed/MEDLINE, Web of Science, and Scopus to identify studies that reported the effects of desert dust and sandstorms on human health. Search terms referred to desert dust or sandstorm exposure, names of major deserts, and health outcomes. Health effects were cross‐tabulated with study design variables (e.g., epidemiological design and methods to quantify dust exposure), desert dust source, health outcomes and conditions. We identified 204 studies that met the inclusion criteria for the scoping review. More than half of the studies (52.9%) used a time‐series study design. However, we found a substantial variation in the methods used to identify and quantify desert dust exposure. The binary metric of dust exposure was more frequently used than the continuous metric for all desert dust source locations. Most studies (84.8%) reported significant associations between desert dust and adverse health effects, mainly for respiratory and cardiovascular mortality and morbidity causes. Although there is a large body of evidence on the health effects of desert dust and sandstorms, the existing epidemiological studies have significant limitations related to exposure measurement and statistical analysis that potentially contribute to inconsistencies in determining the effect of desert dust on human health.

Images degraded by light scattering and absorption, such as hazy, sandstorm, and underwater images, often suffer color distortion and low contrast because of light traveling through turbid media. In order to enhance and restore such images, we first estimate ambient light using the depth-dependent color change. Then, via calculating the difference between the observed intensity and the ambient light, which we call the scene ambient light differential, scene transmission can be estimated. Additionally, adaptive color correction is incorporated into the image formation model (IFM) for removing color casts while restoring contrast. Experimental results on various degraded images demonstrate the new method outperforms other IFM-based methods subjectively and objectively. Our approach can be interpreted as a generalization of the common dark channel prior (DCP) approach to image restoration, and our method reduces to several DCP variants for different special cases of ambient lighting and turbid medium conditions.

Flying helicopters in adverse environmental conditions, such as low heights in arid regions, can be dangerous, especially during landing and take-off, since during hovering, the rotors produce a dust cloud of particles. This phenomenon is known as the "brownout" condition. Unlike visible and infrared systems, the radar devices in the microwave or millimeter wave region offer the capability of sufficient transmission through atmospheric obscurants, such as fog, smoke, sand/dust storms, and brownout. In this work, we present a theoretical evaluation of mm-wave (85–100 GHz) attenuation/scattering and power transfer in brownout conditions. The model includes attenuation/scattering prediction and radiant flux, or power collected by the receiver. We are considering the case of sand grain clouds created by helicopter rotor airflow during landing in arid areas. The evaluated scenarios are brownout environments over ranges up to 50 m. The predicted values from the mathematical model are compared with findings in the field and the literature. A simple model for mm-wave power transfer estimation shows satisfactory agreement with the measured values. [ABSTRACT FROM AUTHOR]

Extreme-wind events not only cause disasters by themselves but can also trigger sandstorms, resulting in significant social and economic losses. Since recent years have experienced more frequent and severe extreme weather events, it is worth to explore how extreme-wind events response to recent climate change and how they impact the sandstorm variation. This work established two indices, EW90 and EW95, to identify extreme-wind events based on the relation between extreme-wind intensity and local-source sandstorm. EW90 and EW95 extreme-wind indices are defined as the daily maximum wind speeds greater than the 90th and 95th quantiles of local long-term historical records. The spatial distributions of EW90 and EW95 extreme-wind events are similar, which is higher in arid and semi-arid and coastal regions, and lower in southern China. Seasonally, extreme-wind events mainly occur in April and May for most areas over China, while they are more frequent from July to August for humid regions. During 1971–2020, both the EW90 and EW95 extreme-wind speeds and annual frequencies have significant decreasing trend (p < 0.01), while the daily mean wind speed does not decrease significantly. Extreme-wind events do not have significant abrupt change as well, while a turning positive trend after 2003 is found for mean wind speed. Moreover, sandstorm days are highly correlated with the EW90 and EW95 extreme-wind events, with linear and partial correlation coefficients around 0.95 and 0.5, respectively, while they do not have significant correlations with mean wind speed. Therefore, the significant reduction of sandstorms over northern China in the past 50 years is mainly due to the substantially decreasing extreme-wind events.

The coupling effects of sandstorm and dust from coal bases themselves can have a major impact on the atmospheric environment as well as on human health. The typical coal resource city of Wuhai in Inner Mongolia was selected in order to study these impacts during a severe sandstorm event in March 2021. Particulate matter (PM1, PM2.5 and PM10) and total suspended particulate matter (TSP) samples were collected during the sandstorm event of 15–19 March 2021 and non-sandstorm weather (11–13 March 2021) and analyzed for their chemical composition. The concentrations of PM1, PM2.5, PM10 and TSP in Wuhai city during the sandstorm were 2.2, 2.6, 4.8 and 6.0 times higher than during non-sandstorm days, respectively. Trace metals concentrations in particles of different sizes generally increased during the sandstorm, while water-soluble ions decreased. Positive matrix fraction (PMF) results showed that the main sources of particles during both sandstorm and non-sandstorm days were industrial emissions, traffic emissions, combustion sources and dust. The proportion of industrial emissions and combustion sources increased compared with non-sandstorm days, while traffic emissions and dust decreased. The backward trajectory analysis results showed that airflows were mainly transported over short distances during non-sandstorm days, and high concentration contribution source areas were from southern Ningxia, southeast Gansu and western Shaanxi. The airflow was mainly transported over long distances during the sandstorm event, and high concentration contribution source areas were from northwestern Inner Mongolia, southern Russia, northern and southwestern Mongolia, and northern Xinjiang. A health risk analysis showed that the risk to human health during sandstorm days related to the chemical composition of particles was generally 1.2–13.1 times higher than during non-sandstorm days. Children were more susceptible to health risks, about 2–6.3 times more vulnerable than adults to the risks from heavy metals in the particles under both weather conditions. [ABSTRACT FROM AUTHOR]

On the 15th of March 2021, the strongest sandstorm in a decade occurred in northern China, and had a great adverse impact on the natural environment and human health in northern China. Real-time monitoring of dust storms is becoming increasingly important. In order to effectively analyze the non-hydrostatic delay (ZNHD) anomaly during a sandstorm, the method based on GNSS-derived tropospheric ZNHD residual to monitor the sandstorm is proposed at the same time. We studied the relationship between ZNHD/PWV and PM10/PM2.5 in Beijing, Changchun, Pingliang and Zhongwei before and after sandstorms. The ZNHD time series was then decomposed by singular spectrum analysis (SSA) and the residuals were obtained. The relationship between the GNSS-derived ZNHD residual and PM10 was analyzed. The results show that the impact of the sandstorm on PM10 is greater than that on PM2.5. Before the sandstorm, the correlation between PM10 and ZNHD was low, less than 0.25. When the sandstorm occurred, the correlation between PM10 and ZNHD increased significantly, and the maximum was greater than 0.7. When the sandstorm ended, the correlation between PM10 and ZNHD decreased significantly. Through the relationship between the ZNHD residual and PM10, it can be found that when the peak-to-peak values of the ZNHD residual are all above 80 mm, sandstorms may occur. But Rainfall, snowfall, haze and other abnormal weather can also lead to ZNHD anomalies. [ABSTRACT FROM AUTHOR]

Deemed to be one of the most important problems in desert areas, sandstorms are among regularly-occurring disasters. They particularly affect rural areas due to their vulnerability, causing many economic, livelihood-related, physical, social, cultural, and environmental damages. Reagan County in Kerman province is known as one of the country’s most critical areas in this respect, with recent incidents causing 50 evacuations, and damages to a further 150 villages. Widespread droughts in recent decades have caused a lot of damage to the area’s nomadic communities such Sang Abad. Bearing in mind the frequent recurrence of the hazard, the rural settlements of this area are exposed to gradual decay. Exposure to local and regional sources of sandstorms, the high levels of vulnerability, and the poverty and deprivation necessitates the rehabilitation of the village. The action research method is used here. For two years, the researchers have participated in the reconstruction of Sang Abad village (August 2016 - September 2018). Devising a comprehensive and integrated reconstruction planning for the village, they have intervened in rehabilitation and reconstruction keeping in close contact with the residents. The findings have then gone through process of assessment and valuation obtained from the study of the action research methodology. Bearing in mind the differences between the method used here with those of mainstream approaches to reconstruction studies, the feasibility of using this method in future reconstruction studies is also examined. The results of evaluating rehabilitation and reconstruction activities in Sang Abad have shown the effectiveness of these activities in reducing sandstorm hazards. It also seems that rehabilitation of the economy and livelihood is one of the most critical reconstruction priorities in rehabilitation of rural settlements exposed to sandstorms and in particular Sangabad.

Pulmonary alveolar microlithiasis (PAM) is a rare autosomal recessive disorder characterized by diffuse bilateral deposition of calcispherites in lung alveoli due to mutations in the SLC34A2 gene. Here, we presented a case of PAM in a young male who had been referred to our center to rule out miliary tuberculosis due to his chest radiography findings of bilateral extensive reticulonodular opacities. Possibility of PAM was considered here due to clinicoradiological dissociation and was confirmed with high-resolution computed tomography of the chest, which showed findings of Stage 2 PAM. Even though PAM has pathognomonic unique chest radiographic findings, it always poses a diagnostic challenge for physicians as it closely resembles other diseases including miliary tuberculosis, pneumoconiosis, and sarcoidosis. This case shows the need for thorough knowledge about PAM that physicians should have to reach at early prompt diagnosis and to avoid unnecessary need for invasive procedures.

The emission, transport, and deposition of dust are frequently the focus of dust aerosol studies. However, owing to limited observation data, few studies have examined the relationships between the key parameters of dust transport, especially in typical dust source areas. Therefore, investigating the relationship between near-surface horizontal dust fluxes and dust depositions in typical desert source areas can further help us to understand the movement and transport patterns of dust aerosols. Based on observational experiments on two key transport parameters, this study focused on the quantitative relationship between the horizontal dust flux (Q) and dust deposition (D). A 13-month long dust sample collection experiment was conducted from August 2017 to August 2018 at Xiaotang Station (hereafter XT,40°48′ N, 84°18′ E) and Tazhong Station (hereafter TZ, 39°00′ N, 83°40′ E). The results show that the observed D and Q peaks coincided with periods of high dust storm incidence, with the greatest accumulation observed in spring. Moreover, both Q and D decreased with increasing height in XT, and this phenomenon remained on a monthly scale. In contrast, no clear decreasing pattern in Q and D with increasing height was observed in TZ. Additionally, relatively coarse particles, primarily from local sources, dominated dust depositions in both locations. The proportion of deposited dust particles with a size <20 μm was slightly higher in XT than that in TZ. Specifically, dust depositions in XT contained finer local dust particles and more dust from long-distance transport. Furthermore, D and Q had a significantly positive linear correlation in XT; however, no significant correlation was observed in TZ. Analysis of the wind dynamics and surface dust particle size indicated that topographic differences between the two stations caused these differences in correlation. [ABSTRACT FROM AUTHOR]

Based on ilia observational data, NCEP 1° X 1° reanalysir data and potential vortieita theory, the oeeurrenea mechanism ol a strong sandstorm occurring in Inner Mongolio duvng March 14 - 15 was studied. The resultr show that the larce potential voCex aree io the uppec troposphere moved eastward and downward, and a structure similao te a "funnel" appeared; the cyclone moved eastward and developed; the high potential vortex region always matched the region where the cyclone developed; the development ol' the cyclone was closely related to the cold air activity, and there was an obvious reteraction between high- and low-altitude systems. The potential vorle'ilv at 500 hPa had obvious significancc for the influencing system oS this sandstorm. The 0. 5 PVU contour tine can be used as the boundara oS sandstorm weatUer area. On the potential temperature profile, Wo occurrencc process oS ths sandstorm was the process oS the expansion oS cold air from high latitudes to low latitudes. When the high-value potential vortieita system slide along the isentropic surfacc, the lowee vertical vortieita increased due to the increasing slope oS the isentropic surfacc and the conservation oS potential vortieita, leading to the development oS the surfacc cyclone circulation and the enhancement oS wind speed, and furthee causing the occurrencc oS WIs sandstorm. [ABSTRACT FROM AUTHOR]

The study of the paper aims to present a solar power plant performances and economic benefits of 16.28 kWp grid-tied solar PV systems under the real outdoor conditions in semi-arid area of the Algeria desert. The main goal of this study is to investigate the effectiveness, suitability, feasibility and reliably of these plants on the level of desert areas and under the influence of harsh conditions (desert environment) in the first part. In the second part, the contribution of solar PV plant to conventional networks in the arid and semi-arid environment to assess the rate of integration. Based on experimental measurement data, the paper also shows economic benefits of three photovoltaic plants. It was found that from the first January to last August 2019, the total produced energy by all PV arrays was 171.422 MWh which supplied to the internal grid and while, the consumed energy by the URAER unit was 159,094 kWh. Approximately 10, 95 % of the 159,094 MWh energy consumed in the whole year is provided from the generated PV solar energy that is 17,422 MWh.

Objectives: Sandstorms are natural climate calamities causing severe weather changes and health problems. The sandstorm allied issues are of significant apprehension worldwide, mainly in the present pandemic. This study aims to examine the “sandstorm impact on environmental pollution particulate matter (PM2.5), carbon monoxide (CO), ozone (O3), and daily new cases and deaths due to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)” in Kuwait. Methods: The two incidences of sandstorms occurred in Kuwait, dated 13 March 2021 and 13 June 2021. The data on “PM2.5, CO, NO2, and O3, and SARS-CoV-2 cases and deaths” were documented three weeks before and after both incidences of the sandstorm. For the first incidence, the data was recorded from 18 February to 12 March 2021; and from 13 March to 2 April 2021. However, for the second incidence of sandstorms, data were documented from 23 May to 12 June 2021; and from 13 June to 3 July 2021. The daily “PM2.5, CO, NO2, and O3 levels” were recorded from “Air Quality Index-AQI, metrological web, and data on COVID-19 daily cases and deaths were recorded from the World Health Organization”. Results: After the first and second sandstorm incidence, the air contaminants PM2.5 was increased by 26.62%, CO 22.08%, and O3 increased 18.10% compared to before the sandstorm. SARS-CoV-2 cases were markedly amplified by (21.25%), and deaths were increased by (61.32%) after the sandstorm. Conclusions: Sandstorm events increase air pollutants PM2.5, CO, and O3 levels, and these pollutants increase the SARS-COV-2 daily cases and deaths in Kuwait. The findings have a meaningful memorandum to healthcare representatives to advise the public about the health hazards of the sandstorm and its linkage with SARS-CoV-2 cases and deaths.

Severe sandstorms reoccurred in the spring of 2021 after an absence for more than 10 years in North China. The dust source area, located in Mongolia, suffered destructive cooling and warming in early and late winter, which loosened the land. A lack of precipitation, excessive snow melt and strong evaporation resulted in dry soil and exiguous spring vegetation. A super-strong Mongolian cyclone developed on the bare and loose ground, and easily blew and transported large amounts of sand particles into North China. Furthermore, top-ranking anomalies (sea ice shift in the Barents and Kara Sea, and sea surface temperatures in the east Pacific and northwest Atlantic) were found to induce the aforementioned tremendous climate anomalies in the dust source area. Analyses, based on large-ensemble Coupled Model Intercomparison Project Phase 6, yield results identical to the reanalysis data. Thus, the climate variabilities at different latitudes and synoptic disturbances jointly facilitated the strongest spring sandstorm over the last decade. [ABSTRACT FROM AUTHOR]

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In order to explore the characteristics of climate change in the Hunshandake Sandy Land, the number of gale days, sandstorms, and extreme precipitation events in the sandy land from 1956 to 2018 were analyzed. The results show that in the Hunshandake Sandy Land, the number of gale days was the largest in spring; it first increased and then decreased from 1956 to 2018. The number of gale days was large from 1955 to 1980, and decreased in fluctuation after 1980. Sandstorms mainly occurred in spring; the number of sandstorm days first increased and then decreased. It was the largest during 1966 - 1970, and then decreased slowly; it was the smallest during 1996 -2000. with the anomaly of about -0. 16 d; it rose after the 21sl century. The threshold of extreme precipitation in the sandy land was high in the south and low in the north. The threshold exceeded 80 mm in the southern part of the sandy land, and was less than 50 mm in sandy hinterland and its northern part. The total frequency of extreme precipitation in the sandy land showed an increasing trend year by year. Especially after 1982, the frequency of extreme precipitation rose obviously. Extreme precipitation events mostly happened in July and August. The frequency of extreme precipitation events was the highest in Abaga Banner and the lowest in Duolun County. The maximum daily precipitation appeared in Duolun County, reaching 142.3 mm. [ABSTRACT FROM AUTHOR]

The physical characteristics of sandstorm PM2.5 and the physiological changes of the human body during exercise determine that it is the easiest inhalable particulate matter to enter the body of the moving body through the respiratory system. Epidemiological data indicate that the increase in the concentration of inhalable particles in dust storms is related to the incidence of respiratory diseases in the population. To clarify the toxicological mechanism of the harm to human health caused by exercise in the environment of PM2.5 pollution and to clarify the specific impact of long-term exposure to PM2.5 air pollution on the occurrence and development of chronic diseases in the exercise population should be one of the future research directions. Therefore, this study comprehensively explained the toxicological effects of airborne fine particulate matter (PM2.5) exposure on the tissues and organs of the sports human body from the aspects of animal toxicology experiments and in vivo and in vitro cell experiments, and that the exposure to PM2.5 in sports humans is easier Causes of health risks. Taking the sandstorm and normal weather PM2.5 in Minqin County, Gansu Province collected in March 2019 as experimental samples, the oxidative stress and inflammatory response to model animals and cells were observed through in vivo and in vitro experiments. Research results show that oxidative stress and inflammatory damage caused by PM2.5 are important causes of physical injury in sports. Changes in the breathing pattern, increased breathing rate, increased lung diffusion capacity, and increased heat production during exercise are the reasons why the human body is more likely to be injured in the state of exercise than in the quiet state. Exercising in a high PM2.5 polluted environment will not only offset the benefits of sports to the human body, but also pose a threat to human health. This research carried out research on the toxicological effects of PM2.5 and human health, aiming to provide a basis for revealing the toxic mechanism of sandstorm PM2.5 on humans and animals. This can also evaluate the health impact of the sports crowd under the exposure of sand and dust storm PM2.5, which will become an important scientific basis for continuously strengthening the monitoring and management of certain air pollutants. [ABSTRACT FROM AUTHOR]

The emission, transport, and deposition of dust are frequently the focus of dust aerosol studies. However, owing to limited observation data, few studies have examined the relationships between the key parameters of dust transport, especially in typical dust source areas. Therefore, investigating the relationship between near-surface horizontal dust fluxes and dust depositions in typical desert source areas can further help us to understand the movement and transport patterns of dust aerosols. Based on observational experiments on two key transport parameters, this study focused on the quantitative relationship between the horizontal dust flux (Q) and dust deposition (D). A 13-month long dust sample collection experiment was conducted from August 2017 to August 2018 at Xiaotang Station (hereafter XT,40°48′ N, 84°18′ E) and Tazhong Station (hereafter TZ, 39°00′ N, 83°40′ E). The results show that the observed D and Q peaks coincided with periods of high dust storm incidence, with the greatest accumulation observed in spring. Moreover, both Q and D decreased with increasing height in XT, and this phenomenon remained on a monthly scale. In contrast, no clear decreasing pattern in Q and D with increasing height was observed in TZ. Additionally, relatively coarse particles, primarily from local sources, dominated dust depositions in both locations. The proportion of deposited dust particles with a size D and Q had a significantly positive linear correlation in XT; however, no significant correlation was observed in TZ. Analysis of the wind dynamics and surface dust particle size indicated that topographic differences between the two stations caused these differences in correlation.

The study of the paper aims to present a solar power plant performances and economic benefits of 16.28 kWp grid-tied solar PV systems under the real outdoor conditions of Ghardaïa, located in semi-arid area of the Algeria desert. The main goal of this study is to investigate the effectiveness, suitability, feasibility and reliably of these plants on the level of desert areas and under the influence of harsh conditions (desert environment) in the first part. In the second part, the contribution of solar PV plant to conventional networks in the arid and semi-arid environment to assess the rate of integration. Based on experimental measurement data, the paper also shows economic benefits of three photovoltaic plants. It was found that from the first January to last August 2019, the total produced energy by all PV arrays was 171.422 MWh which supplied to the internal grid and while, the consumed energy by the URAER unit was 159,094 kWh. Approximately 10, 95 % of the 159,094 MWh energy consumed in the whole year is provided from the generated PV solar energy that is 17,422 MWh. The total energy fed to the internal grid has grown from 27 MWh in 05/04/2018 to a maximum of 67.28 MWh recorded in 31/10/2019. The rate of integration of solar energy by all PV arrays in the internal network of the URAER varied between 6, 60% in January and 22, 96% in April. The integration of this renewable energy generation into the local grid in the URAER unit considered satisfactory over this period of operation. From the first January to last August 2019, the cost of electrical energy produced by solar plants is 2090,64 euro(277706,68 Algerian dinars) while the cost of energy consumed by the Applied Research Unit in renewable energies is 4772,82 euro(664853,826 Algerian dinars). [ABSTRACT FROM AUTHOR]

In order to accurately recognize the weather process of strong sandstorms and improve the accuracy of the weather forecast of strong sandstorms, in this paper, we have carried out a systematic diagnostic analysis on the circulation characteristics and physical quantities of strong sandstorms under the background of regional environments. We selected Minqin County, Wuwei, Gansu Province, China, where strong sandstorms are frequent, as the study area, and classified the sandstorms from 2003 to 2012 into two categories: strong and weak according to the sandstorm intensity classification standard under the regional environmental background. On this basis, we implemented an analysis of the circulation characteristics of sandstorms. The results show that the strong and weak sandstorms in the study area have obvious winter circulation differences, and the formation of strong sandstorms is closely related to the winter monsoon. Meanwhile, we conducted a physical diagnosis of the strong dust storm that occurred in the area at 9 o'clock and 21 o'clock on May 27, 2006. The results show that the region where the strong dust storm occurs is relatively positive vorticity and strong convergence below 800 hPa, and negative vorticity and strong auxiliary dispersion above 500 hPa. When a strong sandstorm occurs, the vertical distribution of the helicity above it is negative in the upper part and positive in the lower part. As the center of the negative interval of high-level helicity increases, the interval of strong sandstorms also increases. At this time, the low-level cold advection strengthened. At this time, the lowlevel cold advection strengthened. [ABSTRACT FROM AUTHOR]

Abstract With changing climates globally, we see changes in not just average conditions, but also in extreme events, and such events require special attention due to their unpredictable yet significant impact on native biotas. One such event is the formation of a landscape scar at Zonag Lake caused by a climate change‐induced outburst flooding event that occurred on 15 September 2011. During the winter, the scar region became a new birthplace for sandstorms, and since the flooding, remote sensing monitoring shows that between 2011 and 2020, there were 285 sandstorm days (between November and March), relative to none prior. The outburst flooding event and consequential sandstorms threaten the key lambing area of the Tibetan antelope (Chiru), affect the water balance of the Zonag Lake and downstream lakes, and may even impact on the flow in the Yangtze River. Active human intervention may be needed to repair this new desert spit and reverse the slew of consequences which may otherwise lead to significant population declines in one of the major Chiru breeding grounds due to the progressive loss of vegetation productivity across their main breeding area.

With changing climates globally, we see changes in not just average conditions, but also in extreme events, and such events require special attention due to their unpredictable yet significant impact on native biotas. One such event is the formation of a landscape scar at Zonag Lake caused by a climate change‐induced outburst flooding event that occurred on 15 September 2011. During the winter, the scar region became a new birthplace for sandstorms, and since the flooding, remote sensing monitoring shows that between 2011 and 2020, there were 285 sandstorm days (between November and March), relative to none prior. The outburst flooding event and consequential sandstorms threaten the key lambing area of the Tibetan antelope (Chiru), affect the water balance of the Zonag Lake and downstream lakes, and may even impact on the flow in the Yangtze River. Active human intervention may be needed to repair this new desert spit and reverse the slew of consequences which may otherwise lead to significant population declines in one of the major Chiru breeding grounds due to the progressive loss of vegetation productivity across their main breeding area. [ABSTRACT FROM AUTHOR]

Free space optical (FSO) communication is one of the recent promising new access technologies. FSO provides data transmission with high security and unlimited bandwidth with low cost of installation. Optical signal absorption and scattering are the two main factors of attenuation due to the terrestrial channel. Pointing error is a technical factor that causes attenuation of the signal which results from the misalignment of the transmitter and the receiver. This paper investigates the FSO performance for an atmospheric channel in Alexandria city, Egypt. The study covers the operating wavelength, modulation technique, receiver aperture diameter, and type of photodetector. The study considers the practical average of meteorological measurements for Alexandria city obtained from Egyptian Meteorological Unit. The system performance is evaluated by its bit error rate, signal-to-noise ratio, and the received power at different system parameters. The system is studied by simulation and experimentally using Optisystem ver. 15.2. It is found that the FSO system is so sensitive to the transmitter–receiver misalignment. However, the effect of thermal noise and background noise could not be neglected compared to the resulting pointing error due to the Mediterranean climate which is mainly characterized by high temperature and humidity. After this integrated parametric study for the system performance, we deduced the practical application availability for the system starting from low to higher data rates with respect to climate and system parameters. Therefore, one can ensure that the system can be used on a wider scale of customers. [ABSTRACT FROM AUTHOR]

Mineral dust particles play an important role in the formation of secondary inorganic aerosols, which largely contribute to haze pollution in China. During this study, a haze episode (haze days) and a typical haze process mixed with sandstorm (sandy haze days) were observed in Zhengzhou with a series of high-time-resolution monitoring instruments from November 22 to December 8, 2018. Concentrations of PM 10 and crustal elements clearly increased in the sandy haze days. Concentrations of gaseous pollutants, metallic elements emitted from anthropogenic sources, nitrate, and ammonium during sandy haze days were slightly lower than those during the haze days but still obviously higher than those during the non-haze days. The sulfate concentrations, the sulfate fractions in PM 2.5 , and the sulfur oxidation ratios significantly increased in the sandy haze days. Heterogeneous reactions dominated the conversion of SO 2 during the haze and sandy haze days. Enhanced SO 2 conversion during the sandy haze days may be attributed to the high concentrations of transition metal ions from the sandstorm when the values of relative humidity (RH) were in 30%–70%, and high O 3 at certain time points. Gas-phase NO 2 oxidation reactions were the main pathways for nitrate formation. In the sandy haze days, higher nitrogen oxidation ratio (NOR) at daytime may be associated with higher RH and lower temperature than those in the haze days, which facilitate the gas-to-particle partitioning of nitrate; higher NOR values at night may be attributed to the higher O 3 concentrations, which promoted the formation of N 2 O 5. Image 1 [ABSTRACT FROM AUTHOR]