Dust Storm Frequency Research Articles

Distribution of Trace Elements in Holocene Loess-paleosol Sequence and Environmental Change in Lower Reaches of The Yellow River

Based on field investigation, samples in loess-paleosol sequence profile were collected systematically at Longshan site in Shangdong province in lower reaches of The Yellow River. Trace elements(Mn, Cu, Ba, Ni, Pb, Rb, Sr, Ti, V and Zn) were measured and analyzed systematically by X-Ray and compared with climate substitution index(grain size, Rb/Sr, Ba/Sr). The results as follows:(1) According to the significant correlation between the content of Ti, Ba, Cu, Ni, V, Zn, Rb, Pb, Sr in the LS loess-soil sequence and the index of soil strength (soil grain size, Rb/Sr, Ba/Sr), it can be concluded that the migration and change of trace elements in Holocene period were mainly affected by the environmental evolution of this period. Mn is insensitive to climate change in this profile. The content of Pb in the surface layer of soil is the highest, which may be caused by human activities. (2) The contents of Ti, Ba, Cu, Ni, V, Zn and Rb in the paleosol( S0 ) were accumulated accompanied by the clay(< 5μm) increase while the coarse silt(10∼50μm) reduced, suggesting the intensified pedogenic modification to the accumulated dust when it was humid climate. It implied that the climate was warm and humid during the mid-Holocene optimum. (3) Content of Ti, Ba, Cu, Ni, V, Zn, Rb and clay(< 5μm)in loess layer (Lt, L1, L0) was lower and coarse silt (10-50μm) content was higher when compared with the paleosol layer (S0), suggesting that the intensity of soil formation was weak and aeolian sand activity was frequent. It further indicated that the paleoenvironment was cold and dry with frequent dust storms during the periods of loess formation.

Investigating the Aerosol Optical Depth and Angstrom Exponent and Their Relationships with Meteorological Parameters Over Lahore in Pakistan

In the present work, AERONET (AErosol RObotic NETwork) data of 2006–2014 have been used to analyze the variations in aerosol optical depth (AOD) at 500 nm and Angstrom exponent (440/870) (AE). In order to have an in-depth knowledge of aerosol variability, we have analyzed the association of aerosol properties with the meteorological parameters such as temperature, mean sea level pressure, rainfall, dew point, and dust storm frequency. Long-term observations of MODIS-AOD are also validated with AERONET-AOD over Lahore. The peak monthly mean value of AOD is found in July (1.00 ± 0.34) with the corresponding AE value of 0.85 ± 0.29 pointing toward the fact that desert/soil dust aerosols dominated the atmosphere of Lahore. The lowest value of AOD is found in February (0.47 ± 0.26) with the corresponding AE value of 1.22 ± 0.29 representing the presence of urban/industrial aerosols in the atmosphere over Lahore. The monthly mean AE value is found to be maximum in January (1.36 ± 0.15), whereas lowest value of AE is found in June (0.55 ± 0.25). AOD shows positive correlations with temperature, dew point, relative humidity, visibility, rain and dust storm frequency, and negative with mean sea level pressure and wind speed. AE exhibits positive correlations with relative humidity and mean sea level pressure, while with temperature, dew point, visibility, rain and dust storm frequency, it shows negative correlations.

Satellite Monitoring of Natural Reforestation Efforts in China's Drylands

Desertification in Northern China degrades air quality in China's eastern cities by causing frequent dust storms. To stop desert expansion, China's government initiated the Three-North Shelterbelt Program, a large-scale reforestation project. Many issues with the project have been raised, from the choice of ill-adapted species to planting methods. Recently, the government implemented reforestation'' - closing former pastures to let vegetation regrow naturally. Unfortunately, it has been difficult to estimate the large-scale success of natural reforestation because measuring arid ecosystem productivity is a challenge for optical remote sensing. Here, we use satellite data to monitor vegetation water content and photosynthetic activity, thereby quantifying changes in vegetation biomass and productivity in Northern China. These satellite data corroborate official reforestation data. Our results show that vegetation activity is strongly correlated with both natural and traditional active reforestation, indicating opportunities for new natural reforestation techniques combined with satellite monitoring in other semi-arid regions.

Reconstruction of dust storm frequency in China using the SST signals recorded in coral reefs

The instrumental observations of dust storm (DS) in China and in most countries of the world have only a history of 50–60 years, and the DS variability beyond this timescale cannot be understood properly. Here, we show that the DS frequency can be reconstructed using the coral reef environment records as a proxy. Based on the high-resolution sea surface temperature (SST) records previously reconstructed by Liu et al. (2008) and Sun et al. (2004), we reconstructed the variations of DS frequency and strong wind frequency in China from 1908 to 1959, using the 5-year moving average of the longitudinal SST gradient (GX-H,SST,5m) in the northern South China Sea (SCS) as an indicator. The calibration equation shows that GX-H,SST,5m explains 66% of the variation in the 5-year average of the DS frequency (FDS,5m) and 86% of the variation in the 5-year moving average of strong wind (FSW,5m) in China, respectively. A comparison between the reconstructed long series (1908–1990) and the observed short series (1960–1990) FDS,5m indicates that the mean, maximum, and minimum of the latter series is 10.8, 20.9, and 36.1% smaller than that of the former, demonstrating that the DS frequency strongly depends on timescales; the statistical characteristics over short timescales are quite different from those over long timescales.

Characterization of Eastern Mediterranean dust storms by area of origin; North Africa vs. Arabian Peninsula

The Eastern Mediterranean (EM) Basin is exposed to frequent dust storms during all seasons but summer. The dust is originating from two large sources: a western source, namely North African (mainly Sahara Desert) and an eastern source, the Arabian Peninsula.The characteristics of 53 dust storms (2007–2013) were examined in relation to their origin – western (30) vs. eastern (23). Analysis was done using ground monitoring stations, satellite data and subjective synoptic classification. Significantly higher ground concentration (722 μg/m3 for western events vs 242 μg/m3 for eastern events), higher Aerosol Optical Thickness (AOT) levels (0.50 for western events vs 0.32 for eastern events), longer duration (25 h for western events vs 15 h for eastern events) and stronger surface wind speed (6 m/s for western events vs 4 m/s for eastern events) were found for western origin dust storms. Dust top height was higher for eastern origin events (1.7 km for western events vs 2.3 km for eastern events, non significant). The associated synoptic circulation types dominant during the western origin dust storms are winter cold-core cyclones while for the eastern origin events the Red Sea Trough is the dominant type and occur mainly during fall.The main assumed reasons for these distinguished characteristics (higher ground concentration, AOT levels, longer duration, and surface wind speed) are that western origin cyclones can induce both mobilization and transport of dust. Together with longer dust path and local sources contribution will create a potential for high concentration and long-lasting event as compared to eastern origin events where there is a separation between main mobilization process that occur during summer and the transport westwards necessary to deliver dust to the EM and occurs during non-summer events.

An evaluation of satellite dust-detection algorithms in the Middle East region

ABSTRACT In the last 15 years, the frequency, spatial extent, and intensity of dust storms have increased and it is one of the main continuously occurring environmental hazard in the Middle East region. Since dust storms generally cover a large spatial extent and are highly dynamic, satellite Earth Observation (EO) is a key tool for detecting their occurrence, identifying their origin, and monitoring their transport and state. A variety of satellite dust detection algorithms have been developed to identify dust emissions sources and dust plumes once entrained in the atmosphere. This paper evaluates the performance of five widely applied dust detection algorithms: the Brightness Temperature Difference (BTD), D-parameter, Normalized Difference Dust Index (NDDI), Thermal-Infrared Dust Index (TDI) and the Middle East Dust Index (MEDI). These algorithms are applied to Moderate Resolution Imaging Spectroradiometer (MODIS) data to detect dust-contaminated pixels during three significant dust events in 2007 in the Middle East region that originated from sources in Iraq, Syria and Saudi Arabia. The results indicate that all methods have a comparable performance in detecting dust-contaminated pixels during the three dust events with an average detection rate (between all algorithms) of 85%. However, substantial differences exist in their ability to distinguish dust from clouds and the land surface, which resulted in large errors of commission. Direct validation of these algorithms with observations from seven Aerosol Robotic Network (AERONET) stations in the region found an average false detection rate (between all algorithms) of 89.6%. Although the algorithms performed well in detecting the dust-contaminated pixels their high false detection rate means it is challenging to apply these algorithms in operational context.

Variability of winter haze over the Beijing-Tianjin-Hebei region tied to wind speed in the lower troposphere and particulate sources

This study analyzes the variability of winter haze days and visibility in the Beijing-Tianjin-Hebei (BTH) region, in relation to the regional average wind speed changes in the lower troposphere and emissions for 1961–2014. Winter mean surface meteorological data, NCEP/NCAR atmospheric reanalysis data, and fossil fuel emission data are used. The results reveal a significant increase in the haze days of +0.8 days decade−1 (p < .01), and a subsequent decline in visibility of −1.56 km decade−1 (p < .01). Most interestingly, an accelerated increase in the number of haze days was observed for the last 11-year period (+8.3 days decade−1, p < .01) of the study period (2004–2014). Regression analysis indicates that the increase of haze occurrence and decrease in visibility are partly due to the significant (p < .01) declining trend of the mean wind speed in the lower troposphere (−0.19 m s−1 decade−1 at 10 m, (−0.23 m s−1 decade−1 at 925 hPa), and − 0.21 m s−1 decade−1 at 850 hPa), and partly due to the declining (dust storm frequency as a proxy, −0.41 days dec−1) surrounding particulate sources and increasing fossil fuel emissions (total carbon emission as a proxy, +48,206.8 thousand metric tons dec−1). Specifically, wind speed changes in the lower troposphere explain 41.3% of the interannual varation of the winter haze days and 71.2% of the visibility variance. These are extended to 51.7% and 81.6% respectively when combined with information about the natural (dust storm frequency) and anthropogenic (fossil fuel emissions) particulate sources. Therefore, the analyses show that wind speed changes in the lower troposphere, together with the varied natural and anthropogenic sources of particulates, play a key role in modulating winter haze and visibility conditions in the BTH area.

The Clustering of Severe Dust Storm Occurrence in China From 1958 to 2007

AbstractChina is subjected to severe dust storms that deteriorate air quality and cause substantial damages to environment and socioeconomics. Although the annual frequency of severe dust storms in China has been declining since the 1950s, the variability of severe dust storm occurrence in time and space remains inadequately described under the changing climate. Based on the continuous observation at 368 meteorological observation sites across the mainland China over a 50‐year period (1958 to 2007), we found that the temporal clustering of severe dust storm outbreak has intensified after 1985, which exacerbated the irregularity in the monthly distribution of severe dust storms. Moreover, the timing of the clustering has shown a higher interannual variation after 1985. Therefore, the variability of severe dust storm occurrence has increased significantly since the 1980s at the annual and monthly time scales. In addition, the relative probability of experiencing severe dust storms with a large influential range has risen since the 1980s. Spatially, severe dust storm outbreak has receded from spreading across the country in the 1950s to primarily affecting north and northwest China in the 2000s. These findings suggest a relatively higher risk of dust storm disaster in north and northwest China that is associated with the intensified clustering of severe dust storm activity in both time and space. Continuous studies are needed to identify the favorable synoptic system that stimulates the clustering of severe dust storm outbreak. We advocate more efforts to enhance severe dust storm prediction and warning dissemination in north and northwest China.

Estimating daily and intra-daily PM10 and PM2.5 in Israel using a spatio-temporal hybrid modeling approach

Satellite-based particulate matter (PM) models provide spatially and temporally resolved estimations, allowing greater spatial-temporal coverage compared to sparse ground monitoring stations. The spatio-temporal resolution of these models can be improved using aerosol optical depth (AOD) products from various satellite platforms with different overpass times which can capture possible changes in diurnal aerosol concentrations. Israel is characterized by diverse geo-climatic regions and it is subjected to frequent dust storms events. Our goal was to estimate PM10 and PM2.5 concentrations in Israel on daily and intra-daily (mean PM around the Aqua and Terra overpasses) temporal resolutions and to assess the differences between these time windows. A hybrid modeling approach that consists of three stages was used enabling spatially continuous PM estimations at 1 × 1 km spatial resolution. The model was calibrated on a daily basis applying a mixed modeling approach using MODIS-based MAIAC AOD and various spatial and temporal predictors. It was found that in certain urban areas the measured and estimated PM concentrations during the satellite overpass (Terra or Aqua) were higher than the mean daily PM. The models performed well showing cross-validated R2 that ranged between 0.82 and 0.92. Mean estimated PM for the study period (2005–2015) during days with no dust events showed different spatial patterns for the daily and intra-daily estimations and revealed areas in Israel that are affected by high PM concentrations (mainly industrial or dense urban areas). Estimations from these models are useful for epidemiological research and might contribute to environmental regulatory purposes by focusing the efforts of PM pollution reduction at the identified polluted areas.

The response of transitional pedogenic characteristics of loess in the Yunxian Basin to abrupt climatic events in the northern subtropics since the Last Glacial Maximum

The transitional pedogenic characteristics of loess deposits in the Yunxian Basin have provided solid evidence for understanding the mechanisms of dust transportation, deposition, and detailed documentation of climate instability since the Last Glacial Maximum (LGM) in the northern subtropics of China. The Heinrich Stadial 1b (HS 1b, 16.9–14.7 ka B.P.) event, Bϕlling/Allerϕd (B/A, 13.9–13 ka B.P.) period, Younger Dryas (YD, 12.9–11.7 ka B.P.) event, and an environmental event (5–4 ka B.P.) during the Holocene Optimum were imprinted by the high-resolution multi-proxy of loess-paleosol in the Yunxian Basin, China. Based on granularity and chemical analyses, the loess in the Yunxian Basin can be classified as a fine, clayey loess zone that experienced a moderate degree of chemical weathering. The mechanism forming the transitional pedogenic characteristics was explained by the dust storm frequency data (1957–2007), particle-size data, and multi-proxy records of chemical weathering extent, which was mainly caused by the moderate transport distance from the common provenance and the transitional climatic characteristics of the northern subtropical zone.

The Impacts of Taklimakan Dust Events on Chinese Urban Air Quality in 2015

Aerosols are an important factor affecting air quality. As the largest source of dust aerosol of East Asia, the Taklimakan Desert in Northwest China witnesses frequent dust storm events, which bring about significant impacts on the downstream air quality. However, the scope and timing of the impacts of Taklimakan dust events on Chinese urban air quality have not yet been fully investigated. In this paper, based on multi-source dust data including ground observations, satellite monitoring, and reanalysis products, as well as air quality index (AQI) and the mass concentrations of PM10 and PM2.5 at 367 urban stations in China for 2015, we examined the temporal and spatial characteristics of the impacts of the Taklimakan dust events on downstream urban air quality in China. The results show that the Taklimakan dust events severely affected the air quality of most cities in Northwest China including eastern Xinjiang, Hexi Corridor and Guanzhong Basin, and even northern Southwest China, leading to significant increases in mass concentrations of PM10 and PM2.5 in these cities correlating with the occurrence of dust events. The mass concentrations of PM10 on dust days increased by 11–173% compared with the non-dust days, while the mass concentration of PM2.5 increased by 21–172%. The increments of the mass concentrations of PM10 and PM2.5 on dust days decreased as the distances increased between the cities and the Taklimakan Desert. The influence of the Taklimakan dust events on the air quality in the downstream cities usually persisted for up to four days. The mass concentrations of PM10 and PM2.5 increased successively and the impact duration shortened gradually with increasing distances to the source area as a strong dust storm progressed toward the southeast from the Taklimakan Desert. The peaks of the PM10 concentrations in the downstream cities of eastern Xinjiang, the Hexi Corridor and the Guanzhong Basin occurred on the second, third and fourth days, respectively, after the initiation of the Taklimakan dust storm.

Smart system for dust detecting and removing from solar cells

In the last decades, solar energy gained the most demand as it represents a green and sustainable source of energy. One of the most important obstacles for solar energy production in Iraq is the dirtiness of the panel surface as it causes a shadow that reduces its performance. From other hand, Iraq location has a large frequency of sand dust storms. This research proposed a method to eliminate the impact of dust and dirtiness on the performance of the solar panel in power production. The proposed method monitors the power generation and cleans the photovoltaic surface when required. Arduino Uno microcontroller was used to control the washing task with windscreen wiper tool which energized when the output power dropped to 50% from its rate value. In addition, the proposed method presented a comparison on the solar panel performance with and without the proposed method. The results show the ability of the washing mechanism in maintaining the solar panel performance efficiently after the exposure to dust accumulation.

Temporal and spatial variations in sand and dust storm events in East Asia from 2007 to 2016: Relationships with surface conditions and climate change

We analyzed the frequency and intensity of sand and dust storms (SDSs) in East Asia from 2007 to 2016 using observational data from ground stations, numerical modeling, and vegetation indices obtained from both satellite and reanalysis data. The relationships of SDSs with surface conditions and the synoptic circulation pattern were also analyzed. The statistical analyses demonstrated that the number and intensity of SDS events recorded in spring during 2007 to 2016 showed a decreasing trend. The total number of spring SDSs decreased from at least ten events per year before 2011 to less than ten events per year after 2011. The overall average annual variation of the surface dust concentration in the main dust source regions decreased 33.24μg/m3 (−1.75%) annually. The variation in the temperatures near and below the ground surface and the amount of precipitation and soil moisture all favored an improvement in vegetation coverage, which reduced the intensity and frequency of SDSs. The strong winds accompanying the influx of cold air from high latitudes showed a decreasing trend, leading to a decrease in the number of SDSs and playing a key role in the decadal decrease of SDSs. The decrease in the intensity of the polar vortex during study period was closely related to the decrease in the intensity and frequency of SDSs.

Temporal variations of fine and coarse particulate matter sources in Jeddah, Saudi Arabia

ABSTRACTThis study provides the first comprehensive analysis of the seasonal variations and weekday/weekend differences in fine (aerodynamic diameter <2.5 μm; PM2.5) and coarse (aerodynamic diameter 2.5–10 μm; PM2.5–10) particulate matter mass concentrations, elemental constituents, and potential source origins in Jeddah, Saudi Arabia. Air quality samples were collected over 1 yr, from June 2011 to May 2012 at a frequency of three times per week, and analyzed. The average mass concentrations of PM2.5 (21.9 μg/m3) and PM10 (107.8 μg/m3) during the sampling period exceeded the recommended annual average levels by the World Health Organization (WHO) for PM2.5 (10 μg/m3) and PM10 (20 μg/m3), respectively. Similar to other Middle Eastern locales, PM2.5–10 is the prevailing mass component of atmospheric particulate matter at Jeddah, accounting for approximately 80% of the PM10 mass. Considerations of enrichment factors, absolute principal component analysis (APCA), concentration roses, and backward trajectories identified the following source categories for both PM2.5 and PM2.5–10: (1) soil/road dust, (2) incineration, and (3) traffic; and for PM2.5 only, (4) residual oil burning. Soil/road dust accounted for a major portion of both the PM2.5 (27%) and PM2.5–10 (77%) mass, and the largest source contributor for PM2.5 was from residual oil burning (63%). Temporal variations of PM2.5–10 and PM2.5 were observed, with the elevated concentration levels observed for mass during the spring (due to increased dust storm frequency) and on weekdays (due to increased traffic). The predominant role of windblown soil and road dust in both the PM2.5 and PM2.5–10 masses in this city may have implications regarding the toxicity of these particles versus those in the Western world where most PM health assessments have been made in the past. These results support the need for region-specific epidemiological investigations to be conducted and considered in future PM standard setting.Implications: Temporal variations of fine and coarse PM mass, elemental constituents, and sources were examined in Jeddah, Saudi Arabia, for the first time. The main source of PM2.5–10 is natural windblown soil and road dust, whereas the predominant source of PM2.5 is residual oil burning, generated from the port and oil refinery located west of the air sampler, suggesting that targeted emission controls could significantly improve the air quality in the city. The compositional differences point to a need for health effect studies to be conducted in this region, so as to directly assess the applicability of the existing guidelines to the Middle East air pollution.

Health Impact Assessment Associated with Exposure to PM10 and Dust Storms in Kuwait

Little information is available on the assessment of health impact concerning the Middle Eastern dust storms and PM10 concentration levels despite the aridity of the region and frequent dust storms occurring in this part of the world. A prospective study was conducted to determine the association between dust particles and morbidity and mortality rates for respiratory and cardiovascular diseases in Kuwait. Spearman and Pearson’s correlations were used to identify such associations. Results revealed a significant correlation between dust storms, suspended dust and rising dust (p &lt; 0.01). Correlation between the occurrence of respiratory and cardiovascular diseases and dust storms showed that PM10 concentrations were significantly correlated with bronchial asthma at the 0.05 level (Pearson r = 0.292). Significant correlations at the 0.01 level were shown between bronchial asthma and both acute lower respiratory tract infection (r = 0.737) and acute upper respiratory tract infection (r = 0.839). Respiratory and cardiovascular mortality rates were both equal to 0.62 per 10,000 persons, each corresponding to 8.7% proportionate mortality rate. This study provides a good evidence of the consistent relationship between dust storm events, PM10 concentration levels, and respiratory diseases.

The spatial distribution and accumulation characteristics of heavy metals in steppe soils around three mining areas in Xilinhot in Inner Mongolia, China

Metal deposition has become a major environmental problem in China due to its adverse effects on human and ecosystem health, particularly in Inner Mongolia, where frequent dust storms (due to steppe degradation and desertification) and soil pollution (associated with the increasing mining activities) have occurred in recent decades. To assess spatial distribution of heavy metals and the influences of mining activities on geochemical behavior of heavy metals in soils, soil samples with depth of 0-10, 10-20, and 20-30cm at each site were collected from different directions in the vicinity of three mines (coal mine, gold mine, and fluorite mine) in a typical steppe zone of Inner Mongolia, China. Six elements (Cd, Pb, Zn, Cr, Cu, and Ni) in the soils were analyzed using inductively coupled plasma emission spectrometer (ICP-OES). The results indicated that the average concentrations of Cd, Pb, Zn, Cr, Cu, and Ni in the soil of the study area around three mines were lower than the second class level of the National Soil Environment Safety Standard, but mostly were higher than the background value of soil in the Inner Mongolia. Northwest, southwest, and northeast wind directions have a great influence on the distribution of metals in coal, gold, and fluorite mine area, respectively. The concentration of heavy metals in coal, gold, and fluorite increased with the distance from the center of the mine, then reached a peak, then decreased gradually. The vertical mobility of metals in soil profiles was slightly significant for Cd>Cr>Zn>Ni in coal mine area and was not significant in gold and fluorite mines. Multivariate statistical methods such as principal component analysis and cluster analysis, coupled with correlation coefficient analysis, showed that Cd, Cu, Cr, and Ni in the mining area came from the same source, while Zn and Pb came from the other source. That the sources of heavy metals in the mining area were discussed would not only enhance our knowledge regarding the soil pollution status in the study area but would also provide us information to manage the sources of these elements in the study area.

Spatial and temporal trends of dust storms across desert regions of Iran

Dust storms are among natural and anthropogenic hazards for socioeconomic resources, especially in desert regions. In recent years, dust storms have become a serious problem, especially in desert regions of Iran. This study investigates temporal and spatial variation of dust storm frequency in desert regions of Iran. The number of dusty days (NDD) are collected from 22 stations across the region. The statistical analysis of NDD time series is carried out to show both spatial and seasonal pattern of dust storm occurrence in the region. The regional map of statistical characteristics indicates a north to south increasing dust storm frequency. The spatial map also reveals higher year-to-year variation in south eastern Iran. The seasonality of NDD shows the highest frequency for summer followed by the spring and autumn seasons. The popular Mann–Kendall and the bootstrap MK test to consider serial correlation are then applied for Trend assessment. Results showed both negative (across the north and northwestern regions) and positive trend (across south and south eastern regions) in the annual and seasonal NDD time series. This north-to-south gradient in the spatial and temporal frequency NDD may arise from harsh dry and gusty winds as well as intense land use change in the south eastern territories of Iran. However, more careful and detailed studies are required to connect environmental conditions to change in NDD frequency.

Dust Storms in Northern China: Long-Term Spatiotemporal Characteristics and Climate Controls

Airborne dust derived from desertification in northern China can be transported to East Asia and other regions, impairing human health and affecting the global climate. This study of northern China dust provides an understanding of the mechanism of dust generation and transportation. The authors used dust storm and climatological data from 129 sites and normalized difference vegetation index (NDVI) datasets in northern China to analyze spatiotemporal characteristics and determine the main factors controlling dust storms occurring during 1960–2007. Dust storm–prone areas are consistent with the spatial distribution of northern China deserts where the average wind speed (AWS) is more than 2 m s−1, the mean annual temperature (MAT) ranges from 5° to 10°C, and the mean annual precipitation (MAP) is less than 450 mm. Dust storms commonly occur on spring afternoons in a 3- to 6-h pattern. The three predominant factors that can affect DSF are the maximum wind speed, AWS, and MAT. During 1960–2007, dust storm frequency (DSF) in most regions of northern China fluctuated but had a decreasing trend; this was mainly caused by a gradual reduction in wind speed. The effect of temperature on DSF is complex, as positive and negative correlations exist simultaneously. Temperatures can affect source material (dust, sand, etc.), cyclone activity, and vegetation growth status, which influence the generation of dust storms. NDVI and precipitation are negatively correlated with DSF, but the effect is weak. Vegetation can protect the topsoil environment and prevent dust storm creation but is affected by the primary decisive influence of precipitation.

Irrigation-Induced Environmental Changes around the Aral Sea: An Integrated View from Multiple Satellite Observations

The Aral Sea basin (ASB) is one of the most environmentally vulnerable regions to climate change and human activities. During the past 60 years, irrigation has greatly changed the water distribution and caused severe environmental issues in the ASB. Using remote sensing data, this study investigated the environmental changes induced by irrigation activities in this region. The results show that, in the past decade, land water storage has significantly increased in the irrigated upstream regions (13 km3 year−1) but decreased in the downstream regions (−27 km3 year−1) of the Amu Darya River basin, causing a water storage decrease in the whole basin (−20 km3 year−1). As a result, the water surface area of the Aral Sea has decreased from 32,000 in 2000 to 10,000 km2 in 2015. The shrinking Aral Sea exposed a large portion of the lake bottom to the air, increasing (decreasing) the daytime (nighttime) temperatures by about 1 °C year−1 (0.5 °C year−1). Moreover, there were other potential environmental changes, including drier soil, less vegetation, decreasing cloud and precipitation, and more severe and frequent dust storms. Possible biases in the remote sensing data due to the neglect of the shrinking water surface area of the Aral Sea were identified. These findings highlight the severe environmental threats caused by irrigation in Central Asia and call attention to sustainable water use in such dryland regions.

Identification of dust storm origin in South \u2013West of Iran

BackgroundDeserts are the main sources of emitted dust, and are highly responsive to wind erosion. Low content of soil moisture and lack of vegetation cover lead to fine particle’s release. One of the semi-arid bare lands in Iran, located in the South-West of Iran in Khoozestan province, was selected to investigate Sand and Dust storm potential.MethodsThis paper focused on the metrological parameters of the sampling site, their changes and the relationship between these changes and dust storm occurrence, estimation of Reconaissance Drought Index, the Atterberg limits of soil samples and their relation with soil erosion ability, the chemical composition, size distribution of soil and airborne dust samples, and estimation of vertical mass flux by COMSALT through considering the effect of saffman force and interparticle cohesion forces during warm period (April–September) in 2010. The chemical compositions are measured with X-ray fluorescence, Atomic absorption spectrophotometer and X-ray diffraction. The particle size distribution analysis was conducted by using Laser particle size and sieve techniques.ResultsThere was a strong negative correlation between dust storm occurrence and annual and seasonal rainfall and relative humidity. Positive strong correlation between annual and seasonal maximum temperature and dust storm frequency was seen. Estimation of RDIst in the studied period showed an extremely dry condition. Using the results of particle size distribution and soil consistency, the weak structure of soil was represented. X-ray diffraction analyses of soil and dust samples showed that soil mineralogy was dominated mainly by Quartz and calcite. X-ray fluorescence analyses of samples indicated that the most important major oxide compositions of the soil and airborne dust samples were SiO2, Al2O3, CaO, MgO, Na2O, and Fe2O3, demonstrating similar percentages for soil and dust samples. Estimation of Enrichment Factors for all studied trace elements in soil samples showed Br, Cl, Mo, S, Zn, and Hg with EF values higher than 10.ConclusionThe findings, showed the possible correlation between the degree of anthropogenic soil pollutants, and the remains of Iraq-Iran war. The results expressed sand and dust storm emission potential in this area, was illustrated with measured vertical mass fluxes by COMSALT.