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Sample records for desert dust suppressing

  1. Desert dust suppressing precipitation: A possible desertification feedback loop

    PubMed Central

    Rosenfeld, Daniel; Rudich, Yinon; Lahav, Ronen

    2001-01-01

    The effect of desert dust on cloud properties and precipitation has so far been studied solely by using theoretical models, which predict that rainfall would be enhanced. Here we present observations showing the contrary; the effect of dust on cloud properties is to inhibit precipitation. Using satellite and aircraft observations we show that clouds forming within desert dust contain small droplets and produce little precipitation by drop coalescence. Measurement of the size distribution and the chemical analysis of individual Saharan dust particles collected in such a dust storm suggest a possible mechanism for the diminished rainfall. The detrimental impact of dust on rainfall is smaller than that caused by smoke from biomass burning or anthropogenic air pollution, but the large abundance of desert dust in the atmosphere renders it important. The reduction of precipitation from clouds affected by desert dust can cause drier soil, which in turn raises more dust, thus providing a possible feedback loop to further decrease precipitation. Furthermore, anthropogenic changes of land use exposing the topsoil can initiate such a desertification feedback process. PMID:11353821

  2. Desert Dust and Monsoon Rain

    NASA Technical Reports Server (NTRS)

    Lau, William K. M.; Kim, Kyu-Myong

    2014-01-01

    For centuries, inhabitants of the Indian subcontinent have know that heavy dust events brought on by strong winds occur frequently in the pre-monsoon season, before the onset of heavy rain. Yet scientists have never seriously considered the possibility that natural dust can affect monsoon rainfall. Up to now, most studies of the impacts of aerosols on Indian monsoon rainfall have focused on anthropogenic aerosols in the context of climate change. However, a few recent studies have show that aerosols from antropogenic and natural sources over the Indian subcontinent may affect the transition from break to active monsoon phases on short timescales of days to weeks. Writing in Nature Geoscience, Vinoj and colleagues describe how they have shown that desert dust aerosols over the Arabian Sea and West Asia can strenghten the summer monsoon over the Indial subcontinent in a matter of days.

  3. Desert Dust Satellite Retrieval Intercomparison

    NASA Technical Reports Server (NTRS)

    Carboni, E.; Thomas, G. E.; Sayer, A. M.; Siddans, R.; Poulsen, C. A.; Grainger, R. G.; Ahn, C.; Antoine, D.; Bevan, S.; Braak, R.; Brindley, H.; DeSouza-Mchado, S.; Deuze, J. L.; Diner, D.; Ducos, F.; Grey, W.; Hsu, C.; Kalashnikova, O. V.; Kahn, R.; North, P. R. J.; Salustro, C.; Smith, A.; Tanre, D.; Torres, O.; Veihelmann, B.

    2012-01-01

    This work provides a comparison of satellite retrievals of Saharan desert dust aerosol optical depth (AOD) during a strong dust event through March 2006. In this event, a large dust plume was transported over desert, vegetated, and ocean surfaces. The aim is to identify and understand the differences between current algorithms, and hence improve future retrieval algorithms. The satellite instruments considered are AATSR, AIRS, MERIS, MISR, MODIS, OMI, POLDER, and SEVIRI. An interesting aspect is that the different algorithms make use of different instrument characteristics to obtain retrievals over bright surfaces. These include multi-angle approaches (MISR, AATSR), polarisation measurements (POLDER), single-view approaches using solar wavelengths (OMI, MODIS), and the thermal infrared spectral region (SEVIRI, AIRS). Differences between instruments, together with the comparison of different retrieval algorithms applied to measurements from the same instrument, provide a unique insight into the performance and characteristics of the various techniques employed. As well as the intercomparison between different satellite products, the AODs have also been compared to co-located AERONET data. Despite the fact that the agreement between satellite and AERONET AODs is reasonably good for all of the datasets, there are significant differences between them when compared to each other, especially over land. These differences are partially due to differences in the algorithms, such as as20 sumptions about aerosol model and surface properties. However, in this comparison of spatially and temporally averaged data, at least as significant as these differences are sampling issues related to the actual footprint of each instrument on the heterogeneous aerosol field, cloud identification and the quality control flags of each dataset.

  4. Wind modeling of Chihuahuan Desert dust outbreaks

    NASA Astrophysics Data System (ADS)

    Rivera Rivera, Nancy I.; Gill, Thomas E.; Gebhart, Kristi A.; Hand, Jennifer L.; Bleiweiss, Max P.; Fitzgerald, Rosa M.

    The Chihuahuan Desert region of North America is a significant source of mineral aerosols in the Western Hemisphere, and Chihuahuan Desert dust storms frequently impact the Paso del Norte (El Paso, USA/Ciudad Juarez, Mexico) metropolitan area. A statistical analysis of HYSPLIT back trajectory residence times evaluated airflow into El Paso on all days and on days with synoptic (non-convective) dust events in 2001-2005. The incremental probability—a measure of the areas most likely to have been traversed by air masses arriving at El Paso during dusty days—was only strongly positively associated with the region west-southwest of the city, a zone of known dust source areas. Focused case studies were made of major dust events on 15 April and 15 December 2003. Trajectories approached the surface and MM5 (NCAR/Penn State Mesoscale Model) wind speeds increased at locations consistent with dust sources observed in satellite imagery on those dates. Back trajectory and model analyses suggested that surface cyclones adjacent to the Chihuahuan Desert were associated with the extreme dust events, consistent with previous studies of dust storms in the Southern High Plains to the northeast. The recognition of these meteorological patterns serves as a forecast aid for prediction of dust events likely to impact the Paso del Norte.

  5. Atmospheric transport of mold spores in clouds of desert dust

    USGS Publications Warehouse

    Shinn, E.A.; Griffin, Dale W.; Seba, D.B.

    2003-01-01

    Fungal spores can be transported globally in clouds of desert dust. Many species of fungi (commonly known as molds) and bacteria--including some that are human pathogens--have characteristics suited to long-range atmospheric transport. Dust from the African desert can affect air quality in Africa, Europe, the Middle East, and the Americas. Asian desert dust can affect air quality in Asia, the Arctic, North America, and Europe. Atmospheric exposure to mold-carrying desert dust may affect human health directly through allergic induction of respiratory stress. In addition, mold spores within these dust clouds may seed downwind ecosystems in both outdoor and indoor environments.

  6. Ice nucleation by soil dust compared to desert dust aerosols

    NASA Astrophysics Data System (ADS)

    Moehler, O.; Steinke, I.; Ullrich, R.; Höhler, K.; Schiebel, T.; Hoose, C.; Funk, R.

    2015-12-01

    A minor fraction of atmospheric aerosol particles, so-called ice-nucleating particles (INPs), initiates the formation of the ice phase in tropospheric clouds and thereby markedly influences the Earth's weather and climate systems. Whether an aerosol particle acts as an INP depends on its size, morphology and chemical compositions. The INP fraction of certain aerosol types also strongly depends on the temperature and the relative humidity. Because both desert dust and soil dust aerosols typically comprise a variety of different particles, it is difficult to assess and predict their contribution to the atmospheric INP abundance. This requires both accurate modelling of the sources and atmospheric distribution of atmospheric dust components and detailed investigations of their ice nucleation activities. The latter can be achieved in laboratory experiments and parameterized for use in weather and climate models as a function of temperature and particle surface area, a parameter called ice-nucleation active site (INAS) density. Concerning ice nucleation activity studies, the soil dust is of particular interest because it contains a significant fraction of organics and biological components, both with the potential for contributing to the atmospheric INP abundance at relatively high temperatures compared to mineral components. First laboratory ice nucleation experiments with a few soil dust samples indicated their INP fraction to be comparable or slightly enhanced to that of desert dust. We have used the AIDA (Aerosol Interaction and Dynamics in the Atmosphere) cloud simulation chamber to study the immersion freezing ability of four different arable soil dusts, sampled in Germany, China and Argentina. For temperatures higher than about -20°C, we found the INP fraction of aerosols generated from these samples by a dry dispersion technique to be significantly higher compared to various desert dust aerosols also investigated in AIDA experiments. In this contribution, we

  7. Factors influencing dust suppressant effectiveness

    SciTech Connect

    Copeland, C.R.; Eisele, T.C.; Chesney, D.J.; Kawatra, S.K.

    2008-11-15

    Water sprays are a common method used to reduce particulate matter (PM) emissions. Various factors such as wettability, surface area coverage, fine particle engulfment rates, interparticle adhesion forces, suppressant penetration and suppressant longevity have all been suggested as critical factors in achieving effective PM control. However, it has not been established which of these factors are the most important. Experimental work indicated that suppressant penetration is the most critical of these factors. The length of time after application that suppressants were effective was also improved by using hygroscopic reagents that retained moisture to prevent evaporation. Maximizing suppressant penetration and improving suppressant longevity led to an average 86% reduction in PM10 concentrations in laboratory dust tower tests.

  8. 7 CFR 2902.32 - Dust suppressants.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Dust suppressants. 2902.32 Section 2902.32... Items § 2902.32 Dust suppressants. (a) Definition. Products formulated to reduce or eliminate the spread of dust associated with gravel roads, dirt parking lots, or similar sources of dust,...

  9. Lidar Measurements for Desert Dust Characterization: An Overview

    NASA Technical Reports Server (NTRS)

    Mona, L.; Liu, Z.; Mueller, D.; Omar, A.; Papayannis, A.; Pappalardo, G.; Sugimoto, N.; Vaughan, M.

    2012-01-01

    We provide an overview of light detection and ranging (lidar) capability for describing and characterizing desert dust. This paper summarizes lidar techniques, observations, and fallouts of desert dust lidar measurements. The main objective is to provide the scientific community, including non-practitioners of lidar observations with a reference paper on dust lidar measurements. In particular, it will fill the current gap of communication between research-oriented lidar community and potential desert dust data users, such as air quality monitoring agencies and aviation advisory centers. The current capability of the different lidar techniques for the characterization of aerosol in general and desert dust in particular is presented. Technical aspects and required assumptions of these techniques are discussed, providing readers with the pros and cons of each technique. Information about desert dust collected up to date using lidar techniques is reviewed. Lidar techniques for aerosol characterization have a maturity level appropriate for addressing air quality and transportation issues, as demonstrated by some first results reported in this paper

  10. Impact and monitoring of dust storms in Taklimakan desert

    NASA Astrophysics Data System (ADS)

    Feng, G. G.; Li, X.; Zheng, Z.

    2012-12-01

    The Taklimakan is China's largest, driest, and warmest desert in total area of 338000km^2 with perimeter of 436 km, it is also known as one of the world's largest shifting-sand deserts. Fully 85 percent of the total area consists of mobile, crescent-shaped sand dunes and are virtually devoid of vegetation. The abundant sand provides material for frequent intense dust storms. The Taklimakan desert fills the expansive Tarim Basin between the Kunlun Mountains and the Tibet Plateau to the south and the Tian Shan Mountains to the north. The Tarim River flows across the basin from west-to-east. In these places, the oases created by fresh surface water support agriculture. Studies outside Xinjiang indicated that 80% dust source of storms was from farmland. Dust storms in the Tarim Basin occur for 20 to 59 days, mainly in spring every year. However, little effort was taken to investigate soil wind erosion and dust emission around the desert. Quantitative understanding of individual dust events in the arid Taklimakan desert, for example, the dust emission rates and the long-range transport, are still incomplete. Therefore, the dust events were observed through routine satellite sensors, lidar instruments, airborne samplers, and surface-based aerosol monitors. Soil wind erosion and suspended particulates emission of four major dust storms from the desert and the typical oasis farmlands at the north rim of the desert were measured using creep sampler, BSNE and TSP at eight heights in 2012. In addition, Aqua satellite AOD data, the NAAPS Global Aeosol model, the CALIPSO satellite products, EPA's AirNow AQI of PM2.5 and HYSPLIT Back Trajectory model were applied to analyze dust transport across the Pacific. Four significant dust storms were observed at the north rim of Taklimakan desert in the spring, 2012. During those events, predominant wind direction ranged from 296 to 334°, wind speed over 7 m/s at 2 m lasted for 471-1074 min, gust wind speed ranged from 11-18m/s. It was

  11. Airborne desert dust and aeromicrobiology over the Turkish Mediterranean coastline

    USGS Publications Warehouse

    Griffin, Dale W.; Kubilay, Nilgün; Kocak, Mustafa; Gray, Mike A.; Borden, Timothy C.; Shinn, Eugene A.

    2007-01-01

    Between 18 March and 27 October 2002, 220 air samples were collected on 209 of 224 calendar days, on top of a coastal atmospheric research tower in Erdemli, Turkey. The volume of air filtered for each sample was 340 liters. Two hundred fifty-seven bacterial and 2598 fungal colony forming units (CFU) were enumerated from the samples using a low-nutrient agar. Ground-based dust measurements demonstrated that the region is routinely impacted by dust generated regionally and from North Africa and that the highest combined percent recovery of total CFU and African dust deposition occurred in the month of April (93.4% of CFU recovery and 91.1% of dust deposition occurred during African dust days versus no African dust present, for that month). A statistically significant correlation was observed (peak regional African dust months of March, April and May; rs=0.576, P=0.000) between an increase in the prevalence of microorganisms recovered from atmospheric samples on dust days (regional and African as determined by ground-based dust measurements), versus that observed on non-dust days. Given the prevalence of atmospherically suspended desert dust and microorganisms observed in this study, and that culture-based studies typically only recover a small fraction (

  12. 40 CFR 279.82 - Use as a dust suppressant.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 28 2012-07-01 2012-07-01 false Use as a dust suppressant. 279.82... (CONTINUED) STANDARDS FOR THE MANAGEMENT OF USED OIL Standards for Use as a Dust Suppressant and Disposal of Used Oil § 279.82 Use as a dust suppressant. (a) The use of used oil as a dust suppressant...

  13. Elemental profiles and signatures of fugitive dusts from Chinese deserts.

    PubMed

    Zhang, Rong; Cao, Junji; Tang, Yanrong; Arimoto, Richard; Shen, Zhenxing; Wu, Feng; Han, Yongming; Wang, Gehui; Zhang, Jiaquan; Li, Guohui

    2014-02-15

    Elemental profiles were determined for size-separated fugitive dust particles produced from Chinese desert and gobi soils. Seventeen surface soil samples from six Chinese deserts were collected, composited, resuspended, and sampled through TSP, PM10, and PM2.5 inlets onto Teflon® filters, which were analyzed for twenty-six elements. Two major dust sources could be distinguished based on differences in crustal and enriched elements-the northwestern (NW) region (Taklimakan Desert, Xinjiang Gobi, and Anxinan Gobi) and northern (N) region (Ulan Buh Desert, Central Inner Mongolia Desert, and Erenhot Gobi). The N sources showed lower concentrations of mineral elements (Fe, K, Na, Ti, Mn, Cr, and Rb in PM10, and Fe, K, Ti, Mn, Co, and V in PM2.5) and higher levels of contaminants (S, Zn, Mo, Cu, Cr, Pb, Cd, and As) than the NW ones, especially in PM2.5. Enrichment factors for Cu, Cr, Zn, Pb, As, Mo, and Cd calculated relative to the upper continental crust showed enrichments of one to two orders-of-magnitude, and they were much higher for N sources than NW ones, implying stronger anthropogenic impacts in north China. Aerosol elemental concentrations during dust events at Horqin, Beijing, and Xi'an matched the mass percentages of mineral elements from their presumptive sources better than the alternative ones, validating the differences between the NW and N sources. Additionally, Na/S, Mg/S, Fe/Al, K/Al, Si/Fe, and Na/Al ratios were suggested to differentiate the two dust source regions. The elemental ratios of Ca/Al, K/Al, Fe/Al, and Ti/Fe in the source regions matched those in aerosols collected downwind, and they can be considered as possible source indicators. PMID:24361747

  14. Satellite Observations of Desert Dust-induced Himalayan Snow Darkening

    NASA Technical Reports Server (NTRS)

    Gautam, Ritesh; Hsu, N. Christina; Lau, William K.-M.; Yasunari, Teppei J.

    2013-01-01

    The optically thick aerosol layer along the southern edge of the Himalaya has been subject of several recent investigations relating to its radiative impacts on the South Asian summer monsoon and regional climate forcing. Prior to the onset of summer monsoon, mineral dust from southwest Asian deserts is transported over the Himalayan foothills on an annual basis. Episodic dust plumes are also advected over the Himalaya, visible as dust-laden snow surface in satellite imagery, particularly in western Himalaya. We examined spectral surface reflectance retrieved from spaceborne MODIS observations that show characteristic reduction in the visible wavelengths (0.47 nm) over western Himalaya, associated with dust-induced solar absorption. Case studies as well as seasonal variations of reflectance indicate a significant gradient across the visible (0.47 nm) to near-infrared (0.86 nm) spectrum (VIS-NIR), during premonsoon period. Enhanced absorption at shorter visible wavelengths and the resulting VIS-NIR gradient is consistent with model calculations of snow reflectance with dust impurity. While the role of black carbon in snow cannot be ruled out, our satellite-based analysis suggests the observed spectral reflectance gradient dominated by dust-induced solar absorption during premonsoon season. From an observational viewpoint, this study underscores the importance of mineral dust deposition toward darkening of the western Himalayan snow cover, with potential implications to accelerated seasonal snowmelt and regional snow albedo feedbacks.

  15. From Desert to Dessert: Why Australian Dust Matters.

    NASA Astrophysics Data System (ADS)

    Hunter, K. A.; Mackie, D. S.; Boyd, P. W.; McTainsh, G. H.

    2006-12-01

    The growth of some types of phytoplankton in several parts of the world ocean, including much of the Southern Ocean, is limited by the supply of iron. Large Australian dust storms uplift, transport and abrade soils, to produce aeolian dust that is a significant source iron to the Southern Ocean. Atmospheric processes that enhance the dissolution of iron from aeolian dusts are of interest and have been studied for material from major dust producing regions like the Sahara, Gobi and Australian deserts; the reported solubility of iron from aeolian dusts ranges from <0.01% to 80%. The characteristic red soils, sands and dusts from Australia are generally believed to consist of quartz grains with a coating of fine grains and crystals of iron oxides, primarily hematite and goethite. The precise mineralogy of soil and dust grain coatings is poorly understood and it also not well known how the coatings are altered during uplift and transport to the ocean. Current models to understand the processes operating during the transport and atmospheric processing of dust include some generalisations and simplifications that are not always warranted and our work has shown the overlooked complexity of the system. Models for aeolian-iron dissolution based on Northern Hemisphere data commonly include the pollutants SOx and NOx. The modern Southern Hemisphere is less polluted and thus resembles past environmental systems. The dissolution of iron from soils of the Saharan, Gobi and Australian deserts in the presence of protons only (i.e. without SOx and NOx) occurs in two phases. The first, faster phase, representing up to 20% of total iron is via a surface-controlled mechanism. The rate determining variable is the exposed surface area of the iron oxides and not the size of the underlying quartz grain. The second, slower, phase of dissolution occurs via the transport-controlled formation of a leached layer. During the simulated aeolian abrasion of Australian soils from dust producing

  16. Active sand dunes are largest dust source in the Sahara Desert

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Atreyee

    2012-09-01

    Dried up lakebeds and playas in the Sahara Desert of North Africa are large sources of dust in the atmosphere. The Bodélé Depression at the southern edge of the Sahara Desert, for example, is the single largest source of dust in the world; on average, 100 dust storms a year originate from the Bodélé Depression. A new study by Crouvi et al., however, finds that active sand dunes could be even bigger sources of desert dust in the atmosphere. Atmospheric dust plays active roles in climate and biological processes in the ocean: It regulates heating at the surface of the Earth; modifies cloud properties that affect rainfall; and acts as the only source of iron, a critical nutrient for microorganisms in the ocean. Little is known about types of dust sources in the Sahara Desert, which alone accounts for more than 50% of the dust in the atmosphere.

  17. Atmospheric Movement of Microorganisms in Clouds of Desert Dust and Implications for Human Health

    PubMed Central

    Griffin, Dale W.

    2007-01-01

    Billions of tons of desert dust move through the atmosphere each year. The primary source regions, which include the Sahara and Sahel regions of North Africa and the Gobi and Takla Makan regions of Asia, are capable of dispersing significant quantities of desert dust across the traditionally viewed oceanic barriers. While a considerable amount of research by scientists has addressed atmospheric pathways and aerosol chemistry, very few studies to determine the numbers and types of microorganisms transported within these desert dust clouds and the roles that they may play in human health have been conducted. This review is a summary of the current state of knowledge of desert dust microbiology and the health impact that desert dust and its microbial constituents may have in downwind environments both close to and far from their sources. PMID:17630335

  18. Atmospheric movement of microorganisms in clouds of desert dust and implications for human health

    USGS Publications Warehouse

    Griffin, Dale W.

    2007-01-01

    Billions of tons of desert dust move through the atmosphere each year. The primary source regions, which include the Sahara and Sahel regions of North Africa and the Gobi and Takla Makan regions of Asia, are capable of dispersing significant quantities of desert dust across the traditionally viewed oceanic barriers. While a considerable amount of research by scientists has addressed atmospheric pathways and aerosol chemistry, very few studies to determine the numbers and types of microorganisms transported within these desert dust clouds and the roles that they may play in human health have been conducted. This review is a summary of the current state of knowledge of desert dust microbiology and the health impact that desert dust and its microbial constituents may have in downwind environments both close to and far from their sources.

  19. Determination of chlorophyll-a concentration under desertic dust.

    NASA Astrophysics Data System (ADS)

    Brajard, Julien; Diouf, Daouda; Brehmer, Patrice; Crépon, Michel; Lazar, Alban; Machu, Eric; Thiria, Sylvie; Capet, Xavier

    2015-04-01

    One major challenge in ocean colour remote sensing is the so-called atmospheric correction. It consists in removing the atmospheric signal from the signal measured from space by a radiometer. If an accurate atmospheric correction is performed, it is thus possible to invert the water-leaving reflectance signal to estimate in-water properties such as the chlorophyll-a concentration. Ocean colour data centers proposed a standard atmospheric correction scheme specific to the sensor they processed (SeaWiFS, MERIS, MODIS, VIIRS, …). They are accurate in most situations (open ocean waters, weakly absorbing aeorols) but fail in some specific cases such as the presence of desertic dust in the atmosphere. In some region, they can lead to exclude large regions of the image from the treatment. In this work, we propose an algorithm to perform the atmospheric correction and to determine the chlorophyll-a concentration under desertic dust. This algorithm, called SOM-NV, is a combination of a classification of the aerosol type using a self-organizing map and an inversion scheme called NeuroVaria. It has been applied to the Senegalo-Mauritanean upwelling using SeaWiFS, MODIS and VIIRS data. The results of SOM-NV have been compared with in-situ measurements (HPLC and microscope) sampled during the UPSEN (UPwelling SENegal) campaigns in 2012 and 2013.

  20. Deciphering the Role of Desert Dust in the Climate Puzzle: The Mediterranean Israeli Dust Experiment (MEIDEX)

    NASA Technical Reports Server (NTRS)

    Levin, Zev; Joseph, Joachim; Mekler, Yuri; Israelevich, Peter; Ganor, Eli; Hilsenrath, Ernest; Janz, Scott

    2002-01-01

    Numerous studies have shown that aerosol particles may be one of the primary agents that can offset the climate warming induced by the increase in the amount of atmospheric greenhouse gases. Desert aerosols are probably the most abundant and massive type of aerosol particles that are present in the atmosphere worldwide. These aerosols are carried over large distances and have various global impacts. They interact with clouds, impact the efficiency of their rain production and change their optical properties. They constitute one of the primary sources of minerals for oceanic life and influence the health of coral reefs. They have direct effects on human health, especially by inducing breathing difficulties in children. It was lately discovered that desert particles carry pathogens from the Sahara desert over the Atlantic Ocean, a fact that may explain the migration of certain types of diseases. Aerosols not only absorb solar radiation but also scatter it, so that their climatic effect is influenced not only by their physical properties and height distribution but also by the reflectivity of the underlying surface. This latter property changes greatly over land and is low over ocean surfaces. Aerosol plumes are emitted from discrete, sporadic sources in the desert areas of the world and are transported worldwide by the atmosphere's wind systems. For example, Saharan dust reaches Mexico City, Florida, Ireland, Switzerland and the Mediterranean region, while Asian dust reaches Alaska, Hawaii and the continental United States. This means that in order to assess its global effects, one must observe dust from space. The Space Shuttle is a unique platform, because it flies over the major deserts of our planet, enabling measurements and remote sensing of the aerosols as they travel from source to sink regions. Such efforts must always be accompanied by in-situ data for validation and calibration, with direct sampling of the airborne particles. MEIDEX is a joint project of

  1. An electrified dust storm over the Negev desert, Israel

    NASA Astrophysics Data System (ADS)

    Yair, Y.; Price, C. G.; Yaniv, R.; Katz, S.

    2015-12-01

    We report on atmospheric electrical measurements conducted at the Wise Observatory in Mitzpe-Ramon, Israel (30035'N, 34045'E) during a massive dust storm that occurred over the Eastern Mediterranean region on 10-11 February 2015. The event transported Saharan dust from Egypt and the Sinai Peninsula in advance of the warm front of a Cyprus low pressure system. Satellite images show the dust plume covering the Negev desert and Southern Israel and moving north. The concentrations of PM10 particles measured by the air-quality monitoring network of the Israeli Ministry of the Environment in Beer-Sheba reached values > 450 μg m-3 and AOT from the AERONET station in Sde-Boker was 1.5 on the 10th. The gradual intensification of the event reached peak values on February 11th of over 1200 μg m-3 and AOT of 1.8. This was the most severe dust event in a decade. Continuous measurements of the fair weather vertical electric field (Ez) and vertical current density (Jz) were conducted with 1 minute temporal resolution. Meteorological data was also recorded at the site. As the dust was advected over the observation site, we noted very large fluctuations in the electrical parameters. Since the onset of the dust storm, the Ez values changed between +1000 and +8000 V m-1 while the Jz fluctuated between -10 pA m2 and +20 pA m2, both on time-scales of a few minutes. These values are a significant departures from the mean fair-weather values measured at the site, which are -~200 V m-1 and ~2 pA m2. The disturbed episodes lasted for several hours on the 10th and 11th and coincided with local meteorological conditions related to the wind direction, which carried large amounts of dust particles. We interpret the rapid changes as caused by the transport of electrically charged dust. Calculation of the total electrical charge during the dust storm will be presented.

  2. Intercomparison of Desert Dust Optical Depth from Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Carboni, E.; Thomas, G. E.; Sayer, A. M.; Siddans, R.; Poulsen, C. A.; Grainger, R. G.; Ahn, C.; Antoine, D.; Bevan, S.; Braak, R.; Brindley, H.; DeSouza-Machado, S.; Deuze, J. L.; Diner, D.; Ducos, F.; Grey, W.; Hsu, C.; Kalashnikova, O. V.; Kahn, R.; North, P. R. J.; Salustro, C.; Smith, A.; Tanre, D.; Torres, O.; Veihelmann, B,

    2012-01-01

    This work provides a comparison of satellite retrievals of Saharan desert dust aerosol optical depth (AOD) during a strong dust event through March 2006. In this event, a large dust plume was transported over desert, vegetated, and ocean surfaces. The aim is to identify the differences between current datasets. The satellite instruments considered are AATSR, AIRS, MERIS, MISR, MODIS, OMI, POLDER, and SEVIRI. An interesting aspect is that the different algorithms make use of different instrument characteristics to obtain retrievals over bright surfaces. These include multi-angle approaches (MISR, AATSR), polarisation measurements (POLDER), single-view approaches using solar wavelengths (OMI, MODIS), and the thermal infrared spectral region (SEVIRI, AIRS). Differences between instruments, together with the comparison of different retrieval algorithms applied to measurements from the same instrument, provide a unique insight into the performance and characteristics of the various techniques employed. As well as the intercomparison between different satellite products, the AODs have also been compared to co-located AERONET data. Despite the fact that the agreement between satellite and AERONET AODs is reasonably good for all of the datasets, there are significant differences between them when compared to each other, especially over land. These differences are partially due to differences in the algorithms, such as assumptions about aerosol model and surface properties. However, in this comparison of spatially and temporally averaged data, it is important to note that differences in sampling, related to the actual footprint of each instrument on the heterogeneous aerosol field, cloud identification and the quality control flags of each dataset can be an important issue.

  3. POTENTIAL ENVIRONMENTAL IMPACTS OF DUST SUPPRESSANTS: "ADVOIDING ANOTHER TIMES BEACH"

    EPA Science Inventory

    In the past decade, there has been an increased use of chemical dust suppressants such as i water, salts, asphalt emulsion, vegetable oils, molasses, synthetic polymers, mulches, and lignin 1 products. Dust suppressants abate dust by changing the physical properties of the soil s...

  4. Health effects of particulate air pollution and airborne desert dust

    NASA Astrophysics Data System (ADS)

    Lelieveld, J.; Pozzer, A.; Giannadaki, D.; Fnais, M.

    2013-12-01

    Air pollution by fine particulate matter (PM2.5) has increased strongly with industrialization and urbanization. In the past decades this increase has taken place at a particularly high pace in South and East Asia. We estimate the premature mortality and the years of human life lost (YLL) caused by anthropogenic PM2.5 and airborne desert dust (DU2.5) on regional and national scales (Giannadaki et al., 2013; Lelieveld et al., 2013). This is based on high-resolution global model calculations that resolve urban and industrial regions in relatively great detail. We apply an epidemiological health impact function and find that especially in large countries with extensive suburban and rural populations, air pollution-induced mortality rates have been underestimated given that previous studies largely focused on the urban environment. We calculate a global premature mortality by anthropogenic aerosols of 2.2 million/year (YLL ≈ 16 million/year) due to lung cancer and cardiopulmonary disease. High mortality rates by PM2.5 are found in China, India, Bangladesh, Pakistan and Indonesia. Desert dust DU2.5 aerosols add about 0.4 million/year (YLL ≈ 3.6 million/year). Particularly significant mortality rates by DU2.5 occur in Pakistan, China and India. The estimated global mean per capita mortality caused by airborne particulates is about 0.1%/year (about two thirds of that caused by tobacco smoking). We show that the highest premature mortality rates are found in the Southeast Asia and Western Pacific regions (about 25% and 46% of the global rate, respectively) where more than a dozen of the most highly polluted megacities are located. References: Giannadaki, D., A. Pozzer, and J. Lelieveld, Modeled global effects of airborne desert dust on air quality and premature mortality, Atmos. Chem. Phys. Discuss. (submitted), 2013. Lelieveld, J., C. Barlas, D. Giannadaki, and A. Pozzer, Model calculated global, regional and megacity premature mortality due to air pollution by ozone

  5. Spatial and temporal variations of blowing dust events in the Taklimakan Desert

    NASA Astrophysics Data System (ADS)

    Yang, Xinghua; Shen, Shuanghe; Yang, Fan; He, Qing; Ali, Mamtimin; Huo, Wen; Liu, Xinchun

    2016-08-01

    The Taklimakan Desert is the source of most blowing dust events in China. However, previous studies of sandstorms in this region have not included data from the inner desert because of the difficulty in making observations in this area. In this study, the spatial and temporal variations of blowing dust events, including sandstorms and blowing sand, and its relations with climatic parameters in the Taklimakan Desert were analyzed using data from ten desert-edge meteorological stations during 1961 to 2010 and two inner-desert meteorological stations during 1988 to 1990, 1996 to 2010, and 1992 to 2010. The results identified two regions (Pishan-Hotan-Minfeng and Xiaotang-Tazhong) where blowing dust events occur on average more than 80 days per year. The regions with the highest occurrence of sandstorms, blowing sand, and blowing dust events were different, with sandstorms centered in the north of the desert (Xiaotang, 46.9 days), whereas the central location for blowing sand (Pishan, 86.4 days) and blowing dust events (Minfeng, 113.5 days) activity was located at the southwestern and southern edges of the desert, respectively. The occurrence of sandstorms generally decreased from 1961 to 2010, while the occurrence of blowing sand increased from 1961 to 1979 and then generally decreased. The temporal variation of blowing dust events was mainly affected by the occurrence of strong wind and daily temperature, with average correlation coefficients of 0.46 and -0.41 for these variables across the whole desert.

  6. Biological effects of desert dust in respiratory epithelial cells and a murine model.

    PubMed

    Ghio, Andrew J; Kummarapurugu, Suryanaren T; Tong, Haiyan; Soukup, Joleen M; Dailey, Lisa A; Boykin, Elizabeth; Ian Gilmour, M; Ingram, Peter; Roggli, Victor L; Goldstein, Harland L; Reynolds, Richard L

    2014-04-01

    As a result of the challenge of recent dust storms to public health, we tested the postulate that desert dust collected in the southwestern United States imparts a biological effect in respiratory epithelial cells and an animal model. Two samples of surface sediment were collected from separate dust sources in northeastern Arizona. Analysis of the PM20 fraction demonstrated that the majority of both dust samples were quartz and clay minerals (total SiO₂ of 52 and 57%). Using respiratory epithelial and monocytic cell lines, the two desert dusts increased oxidant generation, measured by Amplex Red fluorescence, along with carbon black (a control particle), silica, and NIST 1649 (an ambient air pollution particle). Cell oxidant generation was greatest following exposures to silica and the desert dusts. Similarly, changes in RNA for superoxide dismutase-1, heme oxygenase-1, and cyclooxygenase-2 were also greatest after silica and the desert dusts supporting an oxidative stress after cell exposure. Silica, desert dusts, and the ambient air pollution particle NIST 1649 demonstrated a capacity to activate the p38 and ERK1/2 pathways and release pro-inflammatory mediators. Mice, instilled with the same particles, showed the greatest lavage concentrations of pro-inflammatory mediators, neutrophils, and lung injury following silica and desert dusts. We conclude that, comparable to other particles, desert dusts have a capacity to (1) influence oxidative stress and release of pro-inflammatory mediators in respiratory epithelial cells and (2) provoke an inflammatory injury in the lower respiratory tract of an animal model. The biological effects of desert dusts approximated those of silica. PMID:24669951

  7. Biological effects of desert dust in respiratory epithelial cells and a murine model

    USGS Publications Warehouse

    Ghio, Andrew J.; Kummarapurugu, Suryanaren T.; Tong, Haiyan; Soukup, Joleen M.; Dailey, Lisa A.; Boykin, Elizabeth; Gilmour, M. Ian; Ingram, Peter; Roggli, Victor L.; Goldstein, Harland L.; Reynolds, Richard L.

    2014-01-01

    As a result of the challenge of recent dust storms to public health, we tested the postulate that desert dust collected in the southwestern United States imparts a biological effect in respiratory epithelial cells and an animal model. Two samples of surface sediment were collected from separate dust sources in northeastern Arizona. Analysis of the PM20 fraction demonstrated that the majority of both dust samples were quartz and clay minerals (total SiO2 of 52 and 57%). Using respiratory epithelial and monocytic cell lines, the two desert dusts increased oxidant generation, measured by Amplex Red fluorescence, along with carbon black (a control particle), silica, and NIST 1649 (an ambient air pollution particle). Cell oxidant generation was greatest following exposures to silica and the desert dusts. Similarly, changes in RNA for superoxide dismutase-1, heme oxygenase-1, and cyclooxygenase-2 were also greatest after silica and the desert dusts supporting an oxidative stress after cell exposure. Silica, desert dusts, and the ambient air pollution particle NIST 1649 demonstrated a capacity to activate the p38 and ERK1/2 pathways and release pro-inflammatory mediators. Mice, instilled with the same particles, showed the greatest lavage concentrations of pro-inflammatory mediators, neutrophils, and lung injury following silica and desert dusts. We conclude that, comparable to other particles, desert dusts have a capacity to (1) influence oxidative stress and release of pro-inflammatory mediators in respiratory epithelial cells and (2) provoke an inflammatory injury in the lower respiratory tract of an animal model. The biological effects of desert dusts approximated those of silica.

  8. Long-Term Observations of Dust Storms in Sandy Desert Environments

    NASA Astrophysics Data System (ADS)

    Yun, Hye-Won; Kim, Jung-Rack; Choi, Yun-Soo

    2015-04-01

    Mineral dust occupies the largest portion of atmospheric aerosol. Considering the numerous risks that dust poses for socioeconomic and anthropogenic activities, it is crucial to understand sandy desert environments, which frequently generate dust storms and act as a primary source of atmospheric aerosol. To identify mineral aerosol mechanisms, it is essential to monitor desert environmental factors involving dust storm generation in the long term. In this study, we focused on two major environmental factors: local surface roughness and soil moisture. Since installments of ground observation networks in sandy deserts are unfeasible, remote sensing techniques for mining desert environmental factors were employed. The test area was established within the Badain Jaran and Kubuqi Deserts in Inner Mongolia, China, where significant seasonal aeolian processes emit mineral dust that influences all of East Asia. To trace local surface roughness, we employed a multi-angle imaging spectroradiometer (MISR) image sequence to extract multi-angle viewing (MAV) topographic parameters such as normalized difference angular index, which represents characteristics of the target desert topography. The backscattering coefficient from various space-borne SAR and stereotopography were compared with MAV observations to determine calibrated local surface roughness. Soil moisture extraction techniques from InSAR-phase coherence stacks were developed and compiled with advanced scatterometer (ASCAT) soil moisture data. Combined with metrological information such as the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA interim, correlations between intensity of sand dune activity as a proxy of aeolian processes in desert environments, surface wind conditions, and surface soil moisture were traced. Overall, we have confirmed that tracking sandy desert aeolian environments for long-term observations is feasible with space-borne, multi-sensor observations when combined with

  9. Modeling Optical Properties of Mineral Dust over "The Great Indian Desert"

    NASA Astrophysics Data System (ADS)

    Mishra, S.; Tripathi, S. N.

    2007-12-01

    The Thar desert, sometimes also described as 'The Great Indian Desert', lying in the Northwest part of India with an area of 0.32*106 km2, is known to be the source of natural mineral dust . The mineral dust particles are mostly non-spherical having sharp edges, which show different scattering signature compared to that of equivalent spheres while interacting with the radiation. Furthermore accurate mineralogical information, that governs their refractive indices, is essential for scattering calculations. The radiative impacts of dust particles therefore depend on their morphology and mineralogy. Most of the present satellites consider the particle to be spherical while retrieving their optical properties. Some newly launched spacecraft instruments such as MISR accounts for non spherical nature by including spheroid particles in its retrieval algorithm . Clearly there exits a need for improvement in dust model used in retrieval algorithm to account for their sharp edges together with their index of refraction based on the latest chemical composition at the sensing wavelengths. To the best of our knowledge no such attempt has been made to calculate the optical properties of dust particles over the Thar desert. In this study, the optical properties of mineral dust of the Thar desert has been modeled using T-matrix method with realistic dust shapes based on Scanning Electron Microscope images of the dust over the desert with particle size ranging from 0.1-1.0 ìm at wavelengths spanning from ultraviolet to near infrared (0.38-1.2ìm). Representative dust particles shapes considered are sphere, cylinder, spheroids and chebyshev together with realistic mineral dust composition. Mineralogical analysis of airborne dust over Northwest India has revealed the presence of only basic non-metallic minerals such as Quartz, Feldspar, Mica and Calcite, which posses negligible imaginary part of refractive index at considered wavelength domain, however, the subsequent dust sampling

  10. Urban particle size distributions during two contrasting dust events originating from Taklimakan and Gobi Deserts.

    PubMed

    Zhao, Suping; Yu, Ye; Xia, Dunsheng; Yin, Daiying; He, Jianjun; Liu, Na; Li, Fang

    2015-12-01

    The dust origins of the two events were identified using HYSPLIT trajectory model and MODIS and CALIPSO satellite data to understand the particle size distribution during two contrasting dust events originated from Taklimakan and Gobi deserts. The supermicron particles significantly increased during the dust events. The dust event from Gobi desert affected significantly on the particles larger than 2.5 μm, while that from Taklimakan desert impacted obviously on the particles in 1.0-2.5 μm. It is found that the particle size distributions and their modal parameters such as VMD (volume median diameter) have significant difference for varying dust origins. The dust from Taklimakan desert was finer than that from Gobi desert also probably due to other influencing factors such as mixing between dust and urban emissions. Our findings illustrated the capacity of combining in situ, satellite data and trajectory model to characterize large-scale dust plumes with a variety of aerosol parameters. PMID:26367704

  11. Observed 20th Century Desert Dust Variability: Impact on Climate and Biogeochemistry

    SciTech Connect

    Mahowald, Natalie; Kloster, Silvia; Engelstaedter, S.; Moore, Jefferson Keith; Mukhopadhyay, S.; McConnell, J. R.; Albani, S.; Doney, Scott C.; Bhattacharya, A.; Curran, M. A. J.; Flanner, Mark G.; Hoffman, Forrest M; Lawrence, David M.; Lindsay, Keith; Mayewski, P. A.; Neff, Jason; Rothenberg, D.; Thomas, E.; Thornton, Peter E; Zender, Charlie S.

    2010-01-01

    Desert dust perturbs climate by directly and indirectly interacting with incoming solar and outgoing long wave radiation, thereby changing precipitation and temperature, in addition to modifying ocean and land biogeochemistry. While we know that desert dust is sensitive to perturbations in climate and human land use, previous studies have been unable to determine whether humans were increasing or decreasing desert dust in the global average. Here we present observational estimates of desert dust based on paleodata proxies showing a doubling of desert dust during the 20th century over much, but not all the globe. Large uncertainties remain in estimates of desert dust variability over 20th century due to limited data. Using these observational estimates of desert dust change in combination with ocean, atmosphere and land models, we calculate the net radiative effect of these observed changes (top of atmosphere) over the 20th century to be -0.14 {+-} 0.11 W/m{sup 2} (1990-1999 vs. 1905-1914). The estimated radiative change due to dust is especially strong between the heavily loaded 1980-1989 and the less heavily loaded 1955-1964 time periods (-0.57 {+-} 0.46 W/m{sup 2}), which model simulations suggest may have reduced the rate of temperature increase between these time periods by 0.11 C. Model simulations also indicate strong regional shifts in precipitation and temperature from desert dust changes, causing 6 ppm (12 PgC) reduction in model carbon uptake by the terrestrial biosphere over the 20th century. Desert dust carries iron, an important micronutrient for ocean biogeochemistry that can modulate ocean carbon storage; here we show that dust deposition trends increase ocean productivity by an estimated 6% over the 20th century, drawing down an additional 4 ppm (8 PgC) of carbon dioxide into the oceans. Thus, perturbations to desert dust over the 20th century inferred from observations are potentially important for climate and biogeochemistry, and our understanding

  12. Disturbance to desert soil ecosystems contributes to dust-mediated impacts at regional scales

    USGS Publications Warehouse

    Pointing, Stephen B.; Belnap, Jayne

    2014-01-01

    This review considers the regional scale of impacts arising from disturbance to desert soil ecosystems. Deserts occupy over one-third of the Earth’s terrestrial surface, and biological soil covers are critical to stabilization of desert soils. Disturbance to these can contribute to massive destabilization and mobilization of dust. This results in dust storms that are transported across inter-continental distances where they have profound negative impacts. Dust deposition at high altitudes causes radiative forcing of snowpack that leads directly to altered hydrological regimes and changes to freshwater biogeochemistry. In marine environments dust deposition impacts phytoplankton diazotrophy, and causes coral reef senescence. Increasingly dust is also recognized as a threat to human health.

  13. Glaciation temperatures of convective clouds ingesting desert dust, air pollution and smoke from forest fires

    NASA Astrophysics Data System (ADS)

    Rosenfeld, Daniel; Yu, Xing; Liu, Guihua; Xu, Xiaohong; Zhu, Yannian; Yue, Zhiguo; Dai, Jin; Dong, Zipeng; Dong, Yan; Peng, Yan

    2011-11-01

    Heavy aerosol loads have been observed to suppress warm rain by reducing cloud drop size and slowing drop coalescence. The ice forming nuclei (IFN) activity of the same aerosols glaciate the clouds and create ice precipitation instead of the suppressed warm rain. Satellite observations show that desert dust and heavy air pollution over East Asia have similar ability to glaciate the tops of growing convective clouds at glaciation temperature of Tg < ˜ -20°C, whereas similarly heavy smoke from forest fires in Siberia without dust or industrial pollution glaciated clouds at Tg ≤ -33°C. The observation that both smoke and air pollution have same effect on reducing cloud drop size implies that the difference in Tg is due to the IFN activity. This dependence of Tg on aerosol types appears only for clouds with re-5 < 12 μm (re-5 is the cloud drop effective radius at the -5°C isotherm, above which ice rarely forms in cloud tops). For the rest of the clouds the glaciation temperature increases strongly with re-5 with little relation to the aerosol types, reaching Tg> ˜ -15°C for the largest re-5, which are typical to marine clouds in pristine atmosphere.

  14. Epifluorescent direct counts of bacteria and viruses from topsoil of various desert dust storm regions.

    PubMed

    Gonzalez-Martin, Cristina; Teigell-Perez, Nuria; Lyles, Mark; Valladares, Basilio; Griffin, Dale W

    2013-01-01

    Topsoil from arid regions is the main source of dust clouds that move through the earth's atmosphere, and microbial communities within these soils can survive long-range dispersion. Microbial abundance and chemical composition were analyzed in topsoil from various desert regions. Statistical analyses showed that microbial direct counts were strongly positively correlated with calcium concentrations and negatively correlated with silicon concentrations. While variance between deserts was expected, it was interesting to note differences between sample sites within a given desert region, illustrating the 'patchy' nature of microbial communities in desert environments. PMID:22989672

  15. Epifluorescent direct counts of bacteria and viruses from topsoil of various desert dust storm regions

    USGS Publications Warehouse

    Gonzalez-Martin, Cristina; Teigell-Perez, Nuria; Lyles, Mark; Valladares, Basilio; Griffin, Dale W.

    2013-01-01

    Topsoil from arid regions is the main source of dust clouds that move through the earth's atmosphere, and microbial communities within these soils can survive long-range dispersion. Microbial abundance and chemical composition were analyzed in topsoil from various desert regions. Statistical analyses showed that microbial direct counts were strongly positively correlated with calcium concentrations and negatively correlated with silicon concentrations. While variance between deserts was expected, it was interesting to note differences between sample sites within a given desert region, illustrating the 'patchy' nature of microbial communities in desert environments.

  16. Modeling and Satellite Observation of Dust Emission and Transport over the Taklimakan Desert

    NASA Astrophysics Data System (ADS)

    Su, J.; Xu, C.; Huang, J.

    2014-12-01

    Taklimakan Desert is one of the world's largest deserts and the most intense dust source of Asia. It is located in the Tarim Basin (average elevation: 1.1 km) in northwest China and surrounded by high mountains and plateaus (average elevation over 4.5 km). The Taklimakan Desert is a particularly interesting area not only because a large amount of dust particles is emitted into the atmosphere from this region every year, but also due to the very unique orography and the prevailing wind direction in lower troposphere, dust particles can be lofted above 5 km into upper troposphere. In this study, we found that dust particles from the Taklimakan Desert can be vertically transported to Tibetan Plateau (TP) during spring and summer seasons while suspend within boundary layer in autumn and winter by using multi-year Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) observations. We investigated the relationship between dust aerosol optical depth (AOD) and surface wind speeds by using multi-angle imaging spectro radiometer (MISR) observations and ERA-Interim data, and further modified the EROD map in the default Weather Research and Forecasting model with chemistry (WRF-Chem) according this relationship in order to ensure realistic simulations of dust emissions. Cases study shown that the simulated dust horizontal and vertical distributions compares well with satellites observations, and dust particles from the Tarim Basin can be blown up to the TP within one day.

  17. Biological effects of desert dust in respiratory epithelial cells and a murine model.

    EPA Science Inventory

    Abstract As a result of the challenge of recent dust storms to public health, we tested the postulate that desert dust collected in the southwestern United States could impact a biological effect in respiratory epithelial cells and an animal model. Two samples of surface sedime...

  18. Dust absorption over the ``Great Indian Desert'' inferred using ground-based and satellite remote sensing

    NASA Astrophysics Data System (ADS)

    Moorthy, K. Krishna; Babu, S. Suresh; Satheesh, S. K.; Srinivasan, J.; Dutt, C. B. S.

    2007-05-01

    Mineral dust is the single largest contributor of natural aerosols over land. Dust aerosols exhibit high variability in their radiative effects because their composition varies locally. This arises because of the regional distinctiveness of the soil characteristics as well as the accumulation of other aerosol species, such as black carbon, on dust while airborne. To accurately estimate the climate impact of dust, spatial and temporal distribution of its radiative properties are essential. However, this is poorly understood over many regions of the world, including the Indian region. In this paper, infrared (IR) radiance (10.5-12.5 μm) acquired from METEOSAT-5 satellite (˜5-km resolution) is used to retrieve dust aerosol characteristics over the "Great Indian Desert" and adjacent regions. The infrared radiance depression on account of the presence of dust in the atmosphere has been used as an index of dust load, called the Infrared Difference Dust Index (IDDI). Simultaneous, ground-based spectral optical depths estimated at visible and near-infrared wavelengths (using a multiwavelength solar radiometer) are used along with the IDDI to infer the dust absorption. The inferred single scattering albedo of dust was in the range of 0.88-0.94. We infer that dust over the Indian desert is of more absorbing nature (compared with African dust). Seasonally, the absorption is least in summer and most in winter. The large dust absorption leads to lower atmospheric warming of 0.7-1.2 K day-1.

  19. Technology Assessment of Dust Suppression Techniques Applied During Structural Demolition

    SciTech Connect

    Boudreaux, J.F.; Ebadian, M.A.; Williams, P.T.; Dua, S.K.

    1998-10-20

    Hanford, Fernald, Savannah River, and other sites are currently reviewing technologies that can be implemented to demolish buildings in a cost-effective manner. In order to demolish a structure properly and, at the same time, minimize the amount of dust generated from a given technology, an evaluation must be conducted to choose the most appropriate dust suppression technology given site-specific conditions. Thus, the purpose of this research, which was carried out at the Hemispheric Center for Environmental Technology (HCET) at Florida International University, was to conduct an experimental study of dust aerosol abatement (dust suppression) methods as applied to nuclear D and D. This experimental study targeted the problem of dust suppression during the demolition of nuclear facilities. The resulting data were employed to assist in the development of mathematical correlations that can be applied to predict dust generation during structural demolition.

  20. Water uptake of clay and desert dust aerosol particles at sub- and supersaturated water vapor conditions.

    PubMed

    Herich, Hanna; Tritscher, Torsten; Wiacek, Aldona; Gysel, Martin; Weingartner, Ernest; Lohmann, Ulrike; Baltensperger, Urs; Cziczo, Daniel J

    2009-09-28

    Airborne mineral dust particles serve as cloud condensation nuclei (CCN), thereby influencing the formation and properties of warm clouds. It is therefore of atmospheric interest how dust aerosols with different mineralogy behave when exposed to high relative humidity (RH) or supersaturation (SS) with respect to liquid water. In this study the subsaturated hygroscopic growth and the supersaturated cloud condensation nucleus activity of pure clays and real desert dust aerosols were determined using a hygroscopicity tandem differential mobility analyzer (HTDMA) and a cloud condensation nuclei counter (CCNC), respectively. Five different illite, montmorillonite and kaolinite clay samples as well as three desert dust samples (Saharan dust (SD), Chinese dust (CD) and Arizona test dust (ATD)) were investigated. Aerosols were generated both with a wet and a dry disperser. The water uptake was parameterized via the hygroscopicity parameter kappa. The hygroscopicity of dry generated dust aerosols was found to be negligible when compared to processed atmospheric aerosols, with CCNC derived kappa values between 0.00 and 0.02 (the latter corresponds to a particle consisting of 96.7% by volume insoluble material and approximately 3.3% ammonium sulfate). Pure clay aerosols were generally found to be less hygroscopic than natural desert dust particles. The illite and montmorillonite samples had kappa approximately 0.003. The kaolinite samples were less hygroscopic and had kappa=0.001. SD (kappa=0.023) was found to be the most hygroscopic dry-generated desert dust followed by CD (kappa=0.007) and ATD (kappa=0.003). Wet-generated dust showed an increased water uptake when compared to dry-generated samples. This is considered to be an artifact introduced by redistribution of soluble material between the particles. Thus, the generation method is critically important when presenting such data. These results indicate any atmospheric processing of a fresh mineral dust particle which

  1. Characterization of aerosolized bacteria and fungi from desert dust events in Mali, West Africa

    USGS Publications Warehouse

    Kellogg, C.A.; Griffin, Dale W.; Garrison, V.H.; Peak, K.K.; Royall, N.; Smith, R.R.; Shinn, E.A.

    2004-01-01

    Millions of metric tons of African desert dust blow across the Atlantic Ocean each year, blanketing the Caribbean and southeastern United States. Previous work in the Caribbean has shown that atmospheric samples collected during dust events contain living microbes, including plant and opportunistic human pathogens. To better understand the potential downwind public health and ecosystem effects of the dust microbes, it is important to characterize the source population. We describe 19 genera of bacteria and 3 genera of fungi isolated from air samples collected in Mali, a known source region for dust storms, and over which large dust storms travel.

  2. Estimated desert-dust ice nuclei profiles from polarization lidar: methodology and case studies

    NASA Astrophysics Data System (ADS)

    Mamouri, R. E.; Ansmann, A.

    2015-03-01

    A lidar method is presented that permits the estimation of height profiles of ice nuclei concentrations (INC) in desert dust layers. The polarization lidar technique is applied to separate dust and non-dust backscatter and extinction coefficients. The desert dust extinction coefficients σd are then converted to aerosol particle number concentrations APC280 which consider particles with radius > 280 nm only. By using profiles of APC280 and ambient temperature T along the laser beam, the profile of INC can be estimated within a factor of 3 by means of APC-T-INC parameterizations from the literature. The observed close relationship between σd at 500 nm and APC280 is of key importance for a successful INC retrieval. We studied this link by means of AERONET (Aerosol Robotic Network) sun/sky photometer observations at Morocco, Cabo Verde, Barbados, and Cyprus during desert dust outbreaks. The new INC retrieval method is applied to lidar observations of dust layers with the spaceborne lidar CALIOP (Cloud Aerosol Lidar with Orthogonal Polarization) during two overpasses over the EARLINET (European Aerosol Research Lidar Network) lidar site of the Cyprus University of Technology (CUT), Limassol (34.7° N, 33° E), Cyprus. The good agreement between the CALIOP and CUT lidar retrievals of σd, APC280, and INC profiles corroborates the potential of CALIOP to provide 3-D global desert dust APC280 and INC data sets.

  3. Identifying Vulnerability Regions of Dust Outbreaks in East Asian Desert Areas: using SMOS, MODIS, and GLDAS

    NASA Astrophysics Data System (ADS)

    Choi, M.; Kim, H.; Cho, E.

    2015-12-01

    It is now well understood that water, carbon, and energy fluxes at the surface/atmosphere interface are highly dependent on soil moisture (SM). In addition, SM is required to be used as realistic initial states for the SM variables, for climate predictions and weather forecasting. As satellite remote-sensing have developed greatly, global surface SM datasets have been produced based on several satellites. Three satellites-based SM datasets were inter-compared under different land-cover over East Asia to select most reliable satellite for retrieving SM datasets in dust source regions. We estimated satellite sensors with 1) Soil Moisture and Ocean Salinity (SMOS), 2) Advanced Scatterometer (ASCAT), and 3) Advanced Microwave Scanning Radiometer 2 (AMSR2) and Global Land Data Assimilation System (GLDAS) was used as reference datasets. In case of arid areas (desert and semi-desert), SMOS-retrieved SM products showed best accuracy (radiometers have generally exhibited a better performance than scatterometers in dry areas). For this reason, SMOS SM products were utilized to retrieve SM over desert areas. The regions that are susceptible to dust outbreaks were investigated using the dust outbreak probability functions (DOPF). Based on DOPF, about 58% of the total number of dust events occurred in regions with a high level of vulnerability where dust outbreaks were predicted with a probability higher than 60%. The SMOS-based DOPF was calculated to be about 62.4% of the dust outbreak vulnerability (DOV) level of the desert areas. Interestingly, East Asian deserts showed an increasing tendency for a high level of DOV during the study period. Those areas were judged to be sources from which dust could be transported to neighboring countries (e.g., Korea and Japan) which can lead to Asian dust storms. These results may allow us to predict trends of dust outbreaks in order to prepare the corresponding disaster response systems.

  4. Spatial and temporal variations of dust concentrations in the Gobi Desert of Mongolia

    NASA Astrophysics Data System (ADS)

    Jugder, D.; Shinoda, M.; Sugimoto, N.; Matsui, I.; Nishikawa, M.; Park, S.; Chun, Y.; Park, M.

    2011-12-01

    Dust storms in the extensive Gobi and desert-steppe zones of Mongolia occur frequently and sometimes cause serious disasters. Dust storms progress from source regions to downstream regions. This study was the first to examine dust mass concentrations of PM10 (PM2.5) in the Gobi Desert, Mongolia. The monthly mean concentrations of PM10 (PM2.5) reached yearly maxima in December and January owing to air pollution. Both PM10 and PM2.5 concentrations were enhanced from March to May by dust storms. Large amounts of fine dust particles are emitted to the air during the dust storm period in the Gobi Desert of Mongolia. Daily mean concentrations of PM10 (PM2.5) varied 64~234 (40~115) μg m-3 for dust storms in spring. The highest hourly mean concentration of PM10 was 6626 μg m-3 in the Gobi during a dust storm. Averaged concentrations of PM10 (PM2.5) for more than 4h-duration periods of the dust events varied from 204 (101) μg m-3 to 452 (170) μg m-3. For diurnal variations, the maximum PM10 (PM2.5) concentrations occurred in the morning and evening, coinciding with coal usage in private houses. It is evident that human activities can affect local air quality around urban localities in the Gobi of Mongolia. Afternoon peaks in PM10 (PM2.5) concentrations appear to be due to dust storms. Study results on the temporal and spatial distributions and transportation of dust storms, and elevated dust by using Polarization-sensitive Mie-scattering lidars showed that the maximum height of dusty layers over the Gobi Desert of Mongolia during dust storm periods varied from 0.5 to 5.5 km above ground level. The Mie lidar observations detected the base and top heights of elevated dust layers transported from other source regions to the Gobi Desert. The study results suggest source areas of the elevated dust. The lidar parameters showed annual variation of dust storms with higher frequencies in March to May.

  5. Observational study of formation mechanism, vertical structure, and dust emission of dust devils over the Taklimakan Desert, China

    NASA Astrophysics Data System (ADS)

    Liu, Chong; Zhao, Tianliang; Yang, Xinghua; Liu, Feng; Han, Yongxiang; Luan, Zhaopeng; He, Qing; Rood, Mark; Yuen, Wangki

    2016-04-01

    A field observation of dust devils was conducted at Xiaotang over the Taklimakan Desert (TD), China, from 7 to 14 July 2014. The measurements of dust devil opacity with the digital optical method and the observed atmospheric boundary layer conditions were applied to investigate the dust devils' formation mechanism, vertical structure, and dust emissions. The critical conditions in the atmospheric boundary layer for dust devil formation were revealed with the land-air surface temperature difference of higher than 15°C, the enhanced momentum flux and sensible heat flux up to 0.54 kg m-1 s-2 and 327 W m-2, respectively, the weak vertical wind shear with the low wind shear index α < 0.10, and the unstable stratification in the lower atmosphere. Based on observed dust opacities, it is identified that a typical dust devil was vertically structured with central updrafts and peripheral downdrafts of dust particles with the asymmetrically horizontal distribution of dust in a rotating dust column. The vertical flux of near-surface dust emissions was also estimated in a range from 5.4 × 10-5 to 9.6 × 10-5 kg m-2 s-1 for a typical dust devil event over TD.

  6. Saharan Desert Dust Sources: New Insights Based on Aerosol Vertical Profiles Retrieved from Thermal Infrared Measurements by IASI

    NASA Astrophysics Data System (ADS)

    Vandenbussche, S.; Kumps, N.; Vandaele, A. C.; De Maziere, M.

    2015-06-01

    Desert dust is a major actor in the climate and one of the least characterized with respect to its radiative forcing, both direct and indirect. Studies of dust atmospheric load and sources are therefore of great scientific interest. In the last years, we have developed and improved a retrieval strategy to obtain desert dust aerosols vertical profiles, from thermal infrared measurements by IASI. This strategy has been used to process significant amount of IASI data above North Africa. This dataset allows a new insight in the study of Saharan desert dust sources: it provides twice a day, at interesting times considering the dust emission diurnal cycle, vertical profiles of desert dust (not only optical depth), making possible to distinguish local emissions from transported dust.

  7. 40 CFR 279.82 - Use as a dust suppressant.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... suppressant. The State must show that it has a program in place to prevent the use of used oil/hazardous waste... Section 279.82 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS FOR THE MANAGEMENT OF USED OIL Standards for Use as a Dust Suppressant and Disposal...

  8. 40 CFR 279.82 - Use as a dust suppressant.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... suppressant. The State must show that it has a program in place to prevent the use of used oil/hazardous waste... Section 279.82 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS FOR THE MANAGEMENT OF USED OIL Standards for Use as a Dust Suppressant and Disposal...

  9. 40 CFR 279.82 - Use as a dust suppressant.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... suppressant. The State must show that it has a program in place to prevent the use of used oil/hazardous waste... Section 279.82 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS FOR THE MANAGEMENT OF USED OIL Standards for Use as a Dust Suppressant and Disposal...

  10. 40 CFR 279.82 - Use as a dust suppressant.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... suppressant. The State must show that it has a program in place to prevent the use of used oil/hazardous waste... Section 279.82 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS FOR THE MANAGEMENT OF USED OIL Standards for Use as a Dust Suppressant and Disposal...

  11. Estimation of desert-dust-related ice nuclei profiles from polarization lidar

    NASA Astrophysics Data System (ADS)

    Mamouri, Rodanthi-Elisavet; Nisantzi, Argyro; Hadjimitsis, Diofantos; Ansmann, Albert

    2015-04-01

    This paper presents a methodology based on the use of active remote sensing techniques for the estimation of ice nuclei concentrations (INC) for desert dust plumes. Although this method can be applied to other aerosol components, in this study we focus on desert dust. The method makes use of the polarization lidar technique for the separation of dust and non-dust contributions to the particle backscatter and extinction coefficients. The profile of the dust extinction coefficient is converted to APC280 (dust particles with radius larger than 280 nm) and, in a second step, APC280 is converted to INC by means of an APC-INC relationship from the literature. The observed close relationship between dust extinction at 500 nm and APC280 is the key to a successful INC retrieval. The correlation between dust extinction coefficient and APC280 is studied by means of AERONET sun/sky photometer at Morocco, Cape Verde, Barbados, and Cyprus, during situations dominated by desert dust outbreaks. In the present study, polarization lidar observations of the EARLINET (European Aerosol Research Lidar Network) lidar at the Cyprus University of Technology (CUT), Limassol (34.7o N, 33o E), Cyprus were used together with spaceborne lidar observations during CALIPSO satellite overpasses to demonstrate the potential of the new INC retrieval method. A good agreement between the CALIOP (Cloud Aerosol Lidar with Orthogonal Polarization) and our CUT lidar observations regarding the retrieval of dust extinction coefficient, APC280, and INC profiles were found and corroborate the potential of CALIOP to provide 3-D global desert-dust-related INC data sets. In the next step, efforts should be undertaken towards the establishment of a global, height-resolved INC climatology for desert dust plumes. Realistic global INC distributions are required for an improved estimation of aerosol effects on cloud formation and the better quantification of the indirect aerosol effect on climate. Acknowledgements

  12. Impact of the Desert Dust on the Summer Monsoon System over Southwestern North America

    SciTech Connect

    Zhao, Chun; Liu, Xiaohong; Leung, Lai-Yung R.

    2012-04-24

    The radiative forcing of dust emitted from the Southwest United States (US) deserts and its impact on monsoon circulation and precipitation over the North America monsoon (NAM) region are simulated using a coupled meteorology and aerosol/chemistry model (WRF-Chem) for 15 years (1995-2009). During the monsoon season, dust has a cooling effect (-0.90 W m{sup -2}) at the surface, a warming effect (0.40 W m{sup -2}) in the atmosphere, and a negative top-of-the-atmosphere (TOA) forcing (-0.50 W m{sup -2}) over the deserts on 24-h average. Most of the dust emitted from the deserts concentrates below 800 hPa and accumulates over the western slope of the Rocky Mountains and Mexican Plateau. The absorption of shortwave radiation by dust heats the lower atmosphere by up to 0.5 K day{sup -1} over the western slope of the Mountains. Model sensitivity simulations with and without dust for 15 summers (June-July-August) show that dust heating of the lower atmosphere over the deserts strengthens the low-level southerly moisture fluxes on both sides of the Sierra Madre Occidental. It also results in an eastward migration of NAM-driven moisture convergence over the western slope of the Mountains. These monsoonal circulation changes lead to a statistically significant increase of precipitation by up to {approx}40% over the eastern slope of the Mountains (Arizona-New Mexico-Texas regions). This study highlights the interaction between dust and the NAM system and motivates further investigation of possible dust feedback on monsoon precipitation under climate change and the megadrought conditions projected for the future.

  13. Technology Assessment of Dust Suppression Techniques applied During Structural Demolition

    SciTech Connect

    Boudreaux, J.F.; Ebadian, M.A.; Dua, S.K.

    1997-08-06

    Hanford, Fernald, Savannah River, and other sites are currently reviewing technologies that can be implemented to demolish buildings in a cost-effective manner. In order to demolish a structure and, at the same time, minimize the amount of dust generated by a given technology, an evaluation must be conducted to choose the most appropriate dust suppression technology. Thus, the purpose of this research, which was conducted by the Hemispheric Center for Environmental Technology (HCET) at Florida International University (FIU), was to perform an experimental study of dust aerosol abatement (dust suppression) methods as applied to nuclear D and D. This experimental study specifically targeted the problem of dust suppression during demolition. The resulting data were used in the development of mathematical correlations that can be applied to structural demolition. In the Fiscal Year 1996 (FY96), the effectiveness of different dust suppressing agents was investigated for different types of concrete blocks. Initial tests were conducted in a broad particle size range. In Fiscal Year 1997 (FY97), additional tests were performed in the size range in which most of the particles were detected. Since particle distribution is an important parameter for predicting deposition in various compartments of the human respiratory tract, various tests were aimed at determining the particle size distribution of the airborne dust particles. The effectiveness of dust suppressing agents for particles of various size was studied. Instead of conducting experiments on various types of blocks, it was thought prudent to carry out additional tests on blocks of the same type. Several refinements were also incorporated in the test procedures and data acquisition system used in FY96.

  14. Modeling mineral dust emissions from the Sahara desert using new surface properties and soil database

    NASA Astrophysics Data System (ADS)

    Laurent, B.; Marticorena, B.; Bergametti, G.; LéOn, J. F.; Mahowald, N. M.

    2008-07-01

    The present study investigates the mineral dust emissions and the occurrence of dust emission events over the Sahara desert from 1996 to 2001. Mineral dust emissions are simulated over a region extending from 16°N to 38°N and from 19°W to 40°E with a ?° × ?° spatial resolution. The input parameters required by the dust emission model are surface features data (aerodynamic roughness length, dry soil size distribution and texture for erodible soils), and meteorological surface data (mainly surface wind velocity and soil moisture). A map of the aerodynamic roughness lengths is established based on a composition of protrusion coefficients derived from the POLDER-1 surface products. Soil dry size distribution and texture are derived from measurements performed on soil samples from desert areas, and from a soil map derived from a geomorphologic analysis of desert landscapes. Surface re-analyzed meteorological databases (ERA-40) of the European Centre for Medium range Weather Forecasts (ECMWF) are used. The influence of soil moisture on simulated dust emissions is quantified. The main Saharan dust sources identified during the 6-year simulated period are in agreement with the previous studies based on in situ or satellite observations. The relevance of the simulated large dust sources and point sources ("hot spots") is tested using aerosol indexes derived from satellite observations (TOMS Absorbing Aerosol Index and Infrared Dust Difference Index Meteosat). The Saharan dust emissions simulated from 1996 to 2001 range from 585 to 759 Tg a-1. The simulations show marked seasonal cycles with a maximum in summer for the western Sahara and in spring for the eastern Sahara. The interannual variability of dust emissions is pronounced in the eastern part of the Sahara while the emissions from the western Sahara are more regular over the studied period. The soil moisture does not noticeably affect the Saharan dust emissions, their seasonal cycle or their interannual

  15. Concrete Dust Suppression System. Innovative Technology Summary Report

    SciTech Connect

    1998-12-01

    The improved technology is a water-based dust suppression system for controlling concrete dust generated by demolition equipment, in this case a demolition ram. This demonstration was performed to assess the effectiveness of this system to (1) minimize the amount of water used to suppress potentially contaminated dust, (2) focus the water spray on the dust-generating source and (3) minimize the dust cloud generated by the demolition activity. The technology successfully reduced the water required by a factor of eight compared to the traditional (baseline) method, controlled the dust generated, and permitted a reduction in the work force. The water spray can be focused at the ram point, but it is affected by wind. Prior to the use of this dust control system, dust generated by the demolition ram was controlled manually by spraying with fire hoses (the baseline technology). The improved technology is 18% less expensive than the baseline technology for the conditions and parameters of this demonstration, however, the automated system can save up to 80% versus the baseline whenever waste water treatment costs are considered. For demolishing one high-walled room and a long slab with a total of 413 m{sup 3} (14,580 ft{sup 3}) of concrete, the savings are $105,000 (waste water treatment included). The improved technology reduced the need for water consumption and treatment by about 88% which results in most of the savings.

  16. The Impact of Desert Dust Aerosol Radiative Forcing on Global and West African Precipitation

    NASA Astrophysics Data System (ADS)

    Jordan, A.; Zaitchik, B. F.; Gnanadesikan, A.; Dezfuli, A. K.

    2015-12-01

    Desert dust aerosols exert a radiative forcing on the atmosphere, influencing atmospheric temperature structure and modifying radiative fluxes at the top of the atmosphere (TOA) and surface. As dust aerosols perturb radiative fluxes, the atmosphere responds by altering both energy and moisture dynamics, with potentially significant impacts on regional and global precipitation. Global Climate Model (GCM) experiments designed to characterize these processes have yielded a wide range of results, owing to both the complex nature of the system and diverse differences across models. Most model results show a general decrease in global precipitation, but regional results vary. Here, we compare simulations from GFDL's CM2Mc GCM with multiple other model experiments from the literature in order to investigate mechanisms of radiative impact and reasons for GCM differences on a global and regional scale. We focus on West Africa, a region of high interannual rainfall variability that is a source of dust and that neighbors major Sahara Desert dust sources. As such, changes in West African climate due to radiative forcing of desert dust aerosol have serious implications for desertification feedbacks. Our CM2Mc results show net cooling of the planet at TOA and surface, net warming of the atmosphere, and significant increases in precipitation over West Africa during the summer rainy season. These results differ from some previous GCM studies, prompting comparative analysis of desert dust parameters across models. This presentation will offer quantitative analysis of differences in dust aerosol parameters, aerosol optical properties, and overall particle burden across GCMs, and will characterize the contribution of model differences to the uncertainty of forcing and climate response affecting West Africa.

  17. Water uptake of clay and desert dust aerosol particles at sub- and supersaturated water vapor conditions

    SciTech Connect

    Herich, Hanna; Tritscher, Torsten; Wiacek, Aldona; Gysel, Martin; Weingartner, E.; Lohmann, U.; Baltensperger, Urs; Cziczo, Daniel J.

    2009-11-01

    Airborne mineral dust particles serve as cloud condensation nuclei (CCN), thereby influencing the formation and properties of warm clouds. It is therefore of particular interest how dust aerosols with different mineralogy behave when exposed to high relative humidity (RH) or supersaturation with respect to liquid water similar to atmospheric conditions. In this study the sub-saturated hygroscopic growth and the supersaturated cloud condensation nucleus activity of pure clays and real desert dust aerosols was determined using a hygroscopicity tandem differential mobility analyzer (HTDMA) and a cloud condensation nuclei counter (CCNC), respectively. Five different illite, montmorillonite and kaolinite clay samples as well as three desert dust samples (Saharan dust (SD), Chinese dust (CD) and Arizona test dust (ATD)) were used. Aerosols were generated both with a wet and a dry disperser and the water uptake was parameterized via the hygroscopicity parameter, κ. The hygroscopicity of dry generated dust aerosols was found to be negligible when compared to processed atmospheric aerosols, with CCNC derived κ values between 0.00 and 0.02. The latter value can be idealized as a particle consisting of 96.7% (by volume) insoluble material and ~3.3% ammonium sulfate. Pure clay aerosols were found to be generally less hygroscopic than real desert dust particles. All illite and montmorillonite samples had κ~0.003, kaolinites were least hygroscopic and had κ=0.001. SD (κ=0.023) was found to be the most hygroscopic dry-generated desert dust followed by CD (κ=0.007) and ATD (κ=0.003). Wet-generated dust showed an increased water uptake when compared to dry-generated samples. This is considered to be an artifact introduced by redistribution of soluble material between the particles while immersed in an aqueous medium during atomization, thus indicating that specification of the generation method is critically important when presenting such data. Any atmospheric processing of

  18. Effects of Desert Dust on Nutrient Cycling in the San Juan Mountains, Colorado

    NASA Astrophysics Data System (ADS)

    Neff, J. C.; Farmer, L.; Painter, T. H.; Landry, C.; Reynolds, R.

    2005-12-01

    The San Juan Mountains of southwestern Colorado lie downwind from several major deserts and experience several dust-deposition events each year. These events appear related to storms that erode soils in the deserts of the western US and then deposit atmospheric dust from these soils during or after snowfall during large late winter and spring deposition events. To evaluate the biogeochemical implications of eolian deposition, we collected dust from distinct layers deposited into the seasonal snowpack. We also sampled soils and lake sediments in a high-elevation catchment in the San Juan Mountains. Atmospheric dust was characterized by measurements of chemical composition, Sr isotopic content and analysis of the organic and inorganic constituents of deposited eolian material. The origins of snowpack dust in the San Juans were analyzed using atmospheric tracer transport modeling. These analyses suggest that many dust events originate in southern Utah and northern Arizona, areas that have undergone substantial land use change through the 20th century and that experience severe wind erosion of soils during periodic severe droughts. Analyses of 87Sr/86Sr isotope ratios dust, soils, bedrock, and sediments suggest that eolian dust may compose as much as 90% of the near-surface soil (top 5 cm). In alpine lake sediments, Sr isotopes suggest a relatively recent (20th century) increase in the fraction of sediments derived from dust (relative to bedrock) and a similarly large contribution of dust to surface sediments. Sediment chemistry in two small alpine tarns show changes in Ca, Mg, Al, and Fe concentrations that imply increasing dust (vs. bedrock) contributions to lake sediments over the past 100-200 years. Increasing loading of Ca, Mg and P to alpine basins may have implications for alpine and sub-alpine biogeochemical cycling including water quality and plant nutrient use.

  19. Multiple dust sources in the Sahara Desert: The importance of sand dunes

    NASA Astrophysics Data System (ADS)

    Crouvi, Onn; Schepanski, Kerstin; Amit, Rivka; Gillespie, Alan R.; Enzel, Yehouda

    2012-07-01

    We determine the current sources of dust in the Sahara Desert using quantitative correlation between the number of days with dust storms (NDS), derived from remote-sensing data of high temporal resolution, with the distribution of the soil types and geomorphic units. During 2006-8 the source of over 90% of the NDS was found to be sand dunes, leptosols, calcisols, arenosols, and rock debris. In contrast to previous studies, only few dust storms originated from playas and dry lake beds. Land erodibility was estimated by regressing the NDS to the number of days with high-speed wind events, and was found to be high for sand dunes. Clay and fine-silt grains and aggregates are scarce in sand dunes, which most likely produce dust particles through aeolian abrasion of sand grains. Thus, saltating sand grains impacting clay aggregates on playa surfaces cannot be the sole process for generating dust in the Sahara.

  20. Long-wave radiative forcing due to desert dust

    NASA Astrophysics Data System (ADS)

    Gunn, L. N.; Collins, W.

    2011-12-01

    Radiative forcing due to aerosols has been identified by the IPCC as a major contributor to the total radiative forcing uncertainty budget. Optically thick plumes of dust and pollutants extending out from Africa and Asia can be lifted into the middle troposphere and often are transported over synoptic length scales. These events can decrease the upwelling long-wave fluxes at the top of the atmosphere, especially in the mid-infrared "window". Although the long-wave effects of dust are included in model simulations, they are hard to validate in the absence of satellite-driven global estimates. Using hyper spectral satellite measurements (from NASA's AIRS instrument) it is possible to estimate the effect of dust on the outgoing long-wave radiation directly from the measured spectra, by differencing the simulated clear sky radiance spectra (which are calculated using ECMWF analysis) and the observed dust filled radiance spectra (observations from AIRS). We will summarize this method and show global estimates of the dust radiative effect in the long-wave. These global estimates will be used to validate GCM model output and help us to improve our understanding of dust in the global energy budget.

  1. The Influence of Precipitation-Driven Annual Plant Growth on Dust Emission in the Mojave Desert, USA

    NASA Astrophysics Data System (ADS)

    Urban, F. E.; Reynolds, R. L.; Fulton, R. E.

    2009-12-01

    Sparsely vegetated drylands are an important source for dust emission. However, little detail is known about dust generation in response to timing of precipitation and the consequent effects on soil and vegetation dynamics in these settings. This deficiency is especially acute at intermediate landscape scales, tens of meters to several hundred meters. It is essential to consider dust emission at this scale, because it links dust generation at scales of grains and wind tunnels with regional-scale dust examined using remotely sensed data from satellites. Three sites of slightly different geomorphic settings in the vicinity of Soda (dry) Lake were instrumented (in 1999) with meteorological and sediment transport sensors to measure wind erosion through saltating particle detection during high winds. Changes in vegetation in close proximity to the instrumented sites were bi-annually documented through measurements of plant type, cover, and repeat photographic imagery. Whereas high wind events are the dominant driver of saltation and dust emission, emissive conditions prevail only when annual plants are sparse or absent. Results show that wind erosion and dust emission at two study sites are highly variable and that such variability is dominantly related to vegetation type and cover as influenced by the amount and timing of antecedent precipitation. Secondary controls on dust emission are availability of new sediment related to flood deposits at the sites and seasonally differential wind strength. At sites where annual plants respond quickly and advantageously to precipitation, emissive conditions typically shut down because of vegetation growth within two to three months. This cover of annual plants, even when dead, persists in the desert landscape as a stabilizing agent for varying amounts of time, ten months to three years depending on the amount and vegetation type and subsequent input of precipitation and further annual plant growth. The lasting stabilization effect

  2. Desert Dust Exposure Is Associated with Increased Risk of Asthma Hospitalization in Children

    PubMed Central

    Kanatani, Kumiko T.; Ito, Isao; Al-Delaimy, Wael K.; Adachi, Yuichi; Mathews, William C.; Ramsdell, Joe W.

    2010-01-01

    Rationale: Desert dust particles, including quartz, which causes inflammatory responses in the airway in animal studies, are transported to widespread regions around the globe. Epidemiologically, areas impacted by desert dust storms, such as communities in the Middle East and the Caribbean, seem to have higher incidences of asthma than might be expected. Objectives: We investigated the magnitude of association between airborne mineral dust concentration and hospitalization of children for asthma exacerbation by using Light Detection And Ranging (LIDAR) with a polarization analyzer for an exposure measurement, which can distinguish mineral dust particles from other particles. Methods: A case-crossover design was used. The exposure measurement was LIDAR's nonspherical extinction coefficient. The outcome measurement was hospitalization of children aged 1 to 15 years for asthma exacerbation in eight principal hospitals in Toyama, a local area in Japan bordering the Japan Sea, during February to April, 2005 to 2009. Measurements and Main Results: During the study period, there were 620 admissions for asthma exacerbation, and 6 days with a heavy dust event (daily mineral dust concentration > 0.1 mg/m3). Conditional logistic regression showed a statistically significant association between asthma hospitalization and a heavy dust event. The crude odds ratio (OR) of the heavy dust event for hospitalization on the day was 1.88 (95% confidence interval [CI], 1.04–3.41; P = 0.037), and the OR of heavy dust event during the previous week was 1.83 (95% CI, 1.31–2.56; P = 0.00043). The OR adjusted by other air pollutant levels, pollen, and meteorological factors was 1.71 (95% CI, 1.18–2.48; P = 0.0050). Conclusions: Heavy dust events are associated with an increased risk of hospitalizations for asthma. PMID:20656941

  3. MISR perspective on dust spatial and temporal variability in major desert sources

    NASA Astrophysics Data System (ADS)

    Kalashnikova, O. V.; Garay, M. J.; Kassabian, S.; Chodas, M.; Goetz, M. B.; Sokolik, I. N.

    2012-12-01

    Despite its well-recognized importance, the impact of mineral aerosol (dust) on the environment and its relation to global climate factors and mesoscale systems remains difficult to quantify. The 12+ years of data from Multi-angle Imaging SpectroRadiometer (MISR) instrument on the polar-orbiting Terra satellite provide a unique, independent source of data for studying dust emissions. MISR's multiple view angles allow the simultaneous retrieval of dust plume top height and dust motion during the seven minutes a scene is in view. In addition, MISR retrieves aerosol properties over bright surfaces, and such retrievals have been shown to be sensitive to the non-sphericity of dust aerosols. We perform joint analysis of MISR plume stereo products and MISR aerosol optical depth (AOD) products in and downwind of the Bodélé depression in northern Chad, and the Taklimakan desert in East Asia. We evaluate the realism of the MISR characterization of dust source-specific emissions against AERONET and meteorological data. Utilizing the strengths and accounting for biases in MISR aerosol and stereo products over the desert areas, we investigate multi-year spatial and temporal behavior of dust in terms of frequency of plume occurrence, plume heights, dust moving winds, and AOD. In particular, we examine the multi-annual mean pattern, seasonal cycle, inter-annual variability, and trends in dust emissions. MISR does not show statistically significant long-term trends; natural aerosol loadings in the sources and downwind seem to be predominantly affected by large-scale climatological factors and mesoscale weather systems. The reasons for the dust spatial and temporal patterns are analyzed in terms of temperature, precipitation, and wind fields.

  4. Soil-derived sulfate in atmospheric dust particles at Taklimakan desert

    NASA Astrophysics Data System (ADS)

    Wu, Feng; Zhang, Daizhou; Cao, Junji; Xu, Hongmei; An, Zhisheng

    2012-12-01

    Dust-associated sulfate is believed to be a key species which can alter the physical and chemical properties of dust particles in the atmosphere. Its occurrence in the particles has usually been considered to be the consequence of particles' aging in the air although it is present in some crustal minerals. Our observation at the north and south edge of Taklimakan desert, one of the largest dust sources in the Northern Hemisphere, during a dust episode in April 2008 revealed that sulfate in atmospheric dust samples most likely originated directly from surface soil. Its TSP, PM10 and PM2.5 content was proportional to samples' mass and comprised steadily about 4% in the differently sized samples, the ratio of elemental sulfur to iron was approximately constant 0.3, and no demonstrable influence of pollutants from fossil fuel combustion and biomass burning was detected. These results suggest that sulfate could be substantially derived from surface soil at the desert area and the lack of awareness of this origin may impede accurate results in any investigation of atmospheric sulfur chemistry associated with Taklimakan dust and its subsequent local, regional and global effects on the atmosphere.

  5. Analysis of atmospheric vertical profiles in the presence of desert dust aerosols

    NASA Astrophysics Data System (ADS)

    Costa, M. J.; Obregón, M. A.; Pereira, S.; Salgueiro, V.; Potes, M.; Couto, F. T.; Salgado, R.; Bortoli, D.; Silva, A. M.

    2015-12-01

    The present work aims at studying a very recent episode of desert dust transport that affected Iberia in mid May 2015. The dust aerosols were detected over Évora, where a varied set of instrumentation for aerosol measurements is installed, including: a CIMEL sunphotometer integrated in AERONET, a Raman Lidar and a TEOM monitor, as well as ceilometer and a microwave radiometer (profiler). The aerosol occurrence, detected using the columnar, vertically-resolved and in situ measurements, was characterized by a fairly high aerosol optical thickness that reached a value of 1.0 at 440 nm and showed mass concentration peaks at the surface of the order of 100 μg/m3. Subsequently, the tropospheric vertical profiles of humidity and temperature obtained with the passive microwave (MW) radiometer are analysed in order to distinguish possible modifications that can be connected with the transport of desert dust. Modelling results are also examined and the total, SW and LW radiative forcings are investigated, taking into account the different vertical profiles obtained during the desert dust occurrence. It is found that the differences in the atmospheric profiles mostly affect the LW radiative forcing, with an underestimation of about 30% when the actual vertical profile is not considered.

  6. Compositions of modern dust and surface sediments in the Desert Southwest, United States

    USGS Publications Warehouse

    Reheis, M.C.; Budahn, J.R.; Lamothe, P.J.; Reynolds, R.L.

    2009-01-01

    Modern dusts across southwestern United States deserts are compositionally similar to dust-rich Av soil horizons (depths of 0-0.5 cm and 1-4 cm at 35 sites) for common crustal elements but distinctly different for some trace elements. Chemical compositions and magnetic properties of the soil samples are similar among sites relative to dust sources, geographic areas, and lithologic substrates. Exceptions are Li, U, and W, enriched in Owens Valley, California, and Mg and Sr, enriched in soils formed on calcareous fan gravel in southeast Nevada. The Av horizons are dominated by dust and reflect limited mixing with substrate sediments. Modern dust samples are also similar across the region, except that Owens Valley dusts are higher in Mg, Ba, and Li and dusts both there and at sites to the north on volcanic substrates are higher in Sb and W. Thus, dust and Av horizons consist of contributions from many different sources that are well mixed before deposition. Modern dusts contain significantly greater amounts of As, Cd, Cr, Cu, Ni, Pb, and Sb than do Av horizons, which record dust additions over hundreds to thousands of years. These results suggest that modern dust compositions are influenced by anthropogenic sources and emissions from Owens (dry) Lake after its artificial desiccation in 1926. Both modern dusts and Av horizons are enriched in As, Ba, Cu, Li, Sb, Th, U, and W relative to average crustal composition, which we interpret to indicate that the geologic sources of dust in the southwestern United States are geochemically distinctive.

  7. Transport of desert dust mixed with North African industrial pollutants in the subtropical Saharan Air Layer

    NASA Astrophysics Data System (ADS)

    Rodríguez, S.; Alastuey, A.; Alonso-Pérez, S.; Querol, X.; Cuevas, E.; Abreu-Afonso, J.; Viana, M.; Pérez, N.; Pandolfi, M.; de La Rosa, J.

    2011-07-01

    An analysis of chemical composition data of particulate matter samples (TSP, PM10 and PM2.5) collected from 2002 to 2008 in the North Atlantic free troposphere at the Izaña Global Atmospheric Watch (GAW) observatory (Tenerife, Canary Islands) shows that desert dust is very frequently mixed with particulate pollutants in the Saharan Air Layer (SAL). The study of this data set with Median Concentrations At Receptor (MCAR) plots allowed the identification of the potential source regions of the dust and particulate pollutants. Areas located at the south of the southern slope of the Atlas mountains emerge as the most frequent source of the soil desert dust advected to the northern edge of the SAL in summer. Industrial emissions occurring in Northern Algeria, Eastern Algeria, Tunisia and the Atlantic coast of Morocco appear as the most important source of the nitrate, ammonium and a fraction of sulphate (at least 60 % of the sulphate <10 μm transported from some regions) observed in the SAL. These emissions are mostly linked to crude oil refineries, phosphate-based fertilizer industry and power plants. Although desert dust emissions appear as the most frequent source of the phosphorous observed in the SAL, high P concentrations are observed when the SAL is affected by emissions from open mines of phosphate and phosphate based fertilizer industry. The results also show that a significant fraction of the sulphate (up to 90 % of sulphate <10 μm transported from some regions) observed in the SAL may be influenced by soil emissions of evaporite minerals in well defined regions where dry saline lakes (chotts) are present. These interpretations of the MCAR plots are consistent with the results obtained with the Positive Matrix Factorization (PMF2) receptor modelling. The results of this study show that North African industrial pollutants may be mixed with desert dust and exported to the North Atlantic in the Saharan Air Layer.

  8. Transport of desert dust mixed with North African industrial pollutants in the subtropical Saharan Air Layer

    NASA Astrophysics Data System (ADS)

    Rodríguez, S.; Alastuey, A.; Alonso-Pérez, S.; Querol, X.; Cuevas, E.; Abreu-Afonso, J.; Viana, M.; Pandolfi, M.; de La Rosa, J.

    2011-03-01

    The chemical composition of particulate matter samples (TSP, PM10 and PM2.5) collected from 2002 to 2008 in the North Atlantic free troposphere at Izaña Global Atmospheric Watch (GAW) observatory (Tenerife, The Canary Islands) was studied. The analysis of the samples collected in the Saharan Air Layer (SAL) shows that soil desert dust is very frequently mixed with particulate pollutants. An analysis of this data set with Median Concentrations At Receptor (MCAR) plots allowed to identify the potential source regions of the dust and particulate pollutants. Areas located at the south of the Southern slope of Atlas emerge as the most frequent source of the soil desert dust advected to the northern edge of the SAL in summer. Industrial emissions occurring along the Atlantic coast of Morocco, Northern Algeria, Eastern Algeria and Tunisia appear as the most important source of the nitrate, ammonium and a fraction of sulphate (at least a 60% of the sulphate <10 μm transported from some regions) observed in the SAL. These emissions are mostly linked to crude oil refineries, phosphate-based fertilizer industry and power plants. Although desert dust emissions appear as the most frequent source of the phosphorous observed in the SAL, high P concentrations are observed when the SAL is affected by emissions from open mines of phosphate and phosphate based fertilizer industry. The results also show that a significant fraction of the sulphate (up to 90% of sulphate <10 μm transported from some regions) observed in the SAL is linked to soil emissions of evaporite minerals in well defined regions where dry saline lakes (chotts) are present. These interpretations of the MCAR plots are consistent with the results obtained with the Positive Matrix Factorization receptor modelling. The results of this study show that North African industrial pollutants may be mixed with desert dust and exported to the North Atlantic in the Saharan Air Layer.

  9. African and Asian dust: from desert soils to coral reefs

    USGS Publications Warehouse

    Garrison, Virginia H.; Shinn, Eugene A.; Foreman, William T.; Griffin, Dale W.; Holmes, Charles W.; Kellogg, Christina A.; Majewski, Michael S.; Richardson, Laurie L.; Ritchie, Kim B.; Smith, Garriet W.

    2003-01-01

    Many hypotheses have been proposed to explain the decline of coral reefs throughout the world, but none adequately accounts for the lack of recovery of reefs or the wide geographical distribution of coral diseases. The processes driving the decline remain elusive. Hundreds of millions of tons of dust transported annually from Africa and Asia to the Americas may be adversely affecting coral reefs and other downwind ecosystems. Viable microorganisms, macro- and micronutrients, trace metals, and an array of organic contaminants carried in the dust air masses and deposited in the oceans and on land may play important roles in the complex changes occurring on coral reefs worldwide.

  10. Fugitive dust mitigation for PM{sub 10} attainment in the western Mojave Desert: Recommendations on revegetation

    SciTech Connect

    Grantz, D.A.; Vaughn, D.L. |; Roberts, E.

    1997-12-31

    Methods to suppress fugitive dust and associated violations of federal PM{sub 10} standards in the western Mojave Desert, following removal of native vegetation by tillage or overgrazing, have been under investigation by a multi-agency task force for several years. Interim recommendations are now possible for this area of high winds, low rainfall, and mostly arable soil with patchy blowing sand. There can be no guarantee of success in any revegetation program in the desert, but the greatest probability of success in this area can be attained by using the native shrub Atriplex canescens, whether direct seeded or transplanted. No additional nitrogen should be added, and excess nitrogen should be removed if possible, perhaps by a preliminary cropping of barley. This will itself stabilize the soil surface in the short term. Young plants should be protected from herbivory and the harsh elements by using plastic cones. Irrigation is helpful if available. In areas located near native populations of rabbitbrush annual plant cover should be burned but no tillage or other soil disturbance should be imposed, as this facilitates invasion of annual species, including russian thistle, and prevents establishment of rabbitbrush. In sandy areas, seeding with Indian ricegrass may be more effective than with A. canescens. For immediate, short-term, mitigation of blowing dust, furrowing alone and installation of windfences may be effective. Rainfall exhibits high annual variability in arid regions. Absence of fugitive dust emissions in rainy periods, associated with ground cover by annual vegetation, is unlikely to survive several years of low, but normal, rainfall. It is precisely during those periods when rainfall is adequate that long-term revegetation with shrubs has the best chance of success.

  11. Evaporite-mineral Dusts From a Dry Saline Playa in the Mojave Desert and Bioaccessibility of Their Trace Metals

    NASA Astrophysics Data System (ADS)

    Reynolds, R. L.; Breit, G. N.; Goldstein, H.; Morman, S.; Reheis, M. C.; Yount, J. C.; Bogle, R.; Vogel, J.; Ballantine, J.; King, J.

    2008-12-01

    Evaporite-rich sediments commonly form on the surfaces of dust-emitting dry saline lakes, including wet playas, where the depth to the saturated zone is less than about 4 m. These sediments may contain high levels of toxic metals and metalloids, but many important aspects about these kinds of settings remain poorly known: Conditions that promote and suppress dust emission; chemical relations among ground water, salt- rich crusts, and salt-rich dust; bioaccessibility of metals and metalloids in dust; and controls of human activity and climatic variability on dust emission and on metal contents of dust. A dust-emitting area in the Mojave Desert provides a setting where these factors can be evaluated. The area encompasses Ash Meadows to the north where dilute waters (0.7 mS/cm) both discharge and evaporate and Franklin Lake playa (FLP) about 20 km south where saline ground water (90 mS/cm) evaporates. These features are linked by north-to-south flow of shallow ground water in a confined aquifer beneath Carson Slough that has intermediate salinity (1.5- 16 mS/cm). In ground water at FLP, maximum dissolved concentrations of arsenic (16 mg/L), molybdenum (12 mg/L), selenium (0.7 mg/L), tungsten (0.3 mg/L), and uranium (4 mg/L) are explained by evaporative concentration. Monitoring of dust emission from FLP between March 2005 and April 2008, mainly using digital cameras triggered automatically by wind speeds greater than 4.5 m/s, reveals that aridity suppressed dust emission, whereas wet periods promoted dust emission by generating loose accumulations of salt minerals or thin salt crusts that are vulnerable to wind erosion. Samples of dust taken by a portable wind tunnel and of salt crusts contain highly variable contents of toxic metals and metalloids that have high levels of bioaccessibility when leached in fluids that simulate human gastric, intestinal, and lung fluids, with respective pHs of 1.5, 5.5, and 7.4. The levels of bioaccessible toxic substances correspond

  12. Dust suppression in swine feed using soybean oil.

    PubMed

    Mankell, K O; Janni, K A; Walker, R D; Wilson, M E; Pettigrew, J E; Jacobson, L D; Wilcke, W F

    1995-04-01

    Dust generation from swine feed (corn-soybean meal diet) treated with soybean oil was investigated using a cement mixer in a plywood box. Airborne total dust concentrations in the box were measured gravimetrically using a vacuum pump and filters while 12-kg feed samples were constantly mixed. The treatment factors were soybean oil concentration (0, 1, and 3%), corn bulk density (normal, 730 kg/m3 and low, 600 kg/m3), time of oil addition (before vs after grinding the corn), and storage time (0, 7, and 14 d). The feed was a mixture of soybean meal, base mix, and adjusted amounts of ground corn and soybean oil. Adding soybean oil after grinding at 1 and 3% levels to feed made with normal-bulk density corn suppressed total dust generation (3.39 and .99 mg/m3, respectively) (P < .001) compared with the no oil treatment (29.1 mg/m3). The 3% soybean oil treatment suppressed dust generation (.99 mg/m3) more than the 1% soybean oil treatment (3.39 mg/m3) (P < .001). Adding soybean oil after grinding the corn suppressed dust generation more than adding the oil to the corn before grinding for every oil level (P < .001). More dust was generated by feed made from low-bulk density corn than by feed made with normal-bulk density corn at every oil level (P < .001). There was no evidence of any storage time or treatment x storage time interactions. PMID:7628976

  13. The Continuous Monitoring of Desert Dust using an Infrared-based Dust Detection and Retrieval Method

    NASA Technical Reports Server (NTRS)

    Duda, David P.; Minnis, Patrick; Trepte, Qing; Sun-Mack, Sunny

    2006-01-01

    Airborne dust and sand are significant aerosol sources that can impact the atmospheric and surface radiation budgets. Because airborne dust affects visibility and air quality, it is desirable to monitor the location and concentrations of this aerosol for transportation and public health. Although aerosol retrievals have been derived for many years using visible and near-infrared reflectance measurements from satellites, the detection and quantification of dust from these channels is problematic over bright surfaces, or when dust concentrations are large. In addition, aerosol retrievals from polar orbiting satellites lack the ability to monitor the progression and sources of dust storms. As a complement to current aerosol dust retrieval algorithms, multi-spectral thermal infrared (8-12 micron) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Meteosat-8 Spinning Enhanced Visible and Infrared Imager (SEVIRI) are used in the development of a prototype dust detection method and dust property retrieval that can monitor the progress of Saharan dust fields continuously, both night and day. The dust detection method is incorporated into the processing of CERES (Clouds and the Earth s Radiant Energy System) aerosol retrievals to produce dust property retrievals. Both MODIS (from Terra and Aqua) and SEVERI data are used to develop the method.

  14. Stabilization of Desert Surfaces and Accumulation of Dust Under Biological Soil Crusts

    NASA Astrophysics Data System (ADS)

    Finstad, K. M.; Mcnicol, G.; Pfeiffer, M.; Amundson, R.

    2014-12-01

    Biological soil crusts (BSC) are known to play a critical role in the stabilization of desert surfaces by helping to protect sediment from wind and water erosion and aiding in the trapping of airborne particles. The crusts are often composed of cyanobacteria, algae, and fungi, and occupy the upper few cm of a soil. Due to their high tolerance of desiccation and ability to utilize fog and dew sources, BSC are able to exist in environments that may otherwise be too dry for vascular plants. In the hyperarid Atacama Desert, decades or more between measurable precipitation events has created a landscape devoid of macroscopic life. While precipitation is rare, coastal fog occurs regularly and microbial communities capable of utilizing fog and dew water are able to persist. Here we found cyanobacteria and lichen living in association with a thin sulfate and dust crust (~2 cm) covering the surface of 'dust plateaus'. Topographically the region is highly irregular and part of a largely erosional landscape. We hypothesized that these flat-topped plateaus are accretionary features that have been able to maintain dust accumulation for thousands of years as a result of the surface crusts. To test this hypothesis we conducted radiocarbon analysis of crusts and soil profiles at two sites approximately 30 km apart, one in a high fog zone and another in lower fog frequency zone. The radiocarbon analysis shows that sediment has been accumulating in the 'plateaus' for the past 15,000 years and that biological activity and rates of C cycling in the crust increase with increasing fog frequency and intensity. The ages of organic material in the dust decrease monotonically with decreasing soil thickness, suggestive of progressive upward growth by dust accumulation. Our data indicate that the BSC are capable of surviving in hyperarid the Atacama Desert, a Mars analogue, through the utilization of fog water, and that their presence can leave a visible geomorphic imprint on the landscape.

  15. Dust emission from wet and dry playas in the Mojave Desert, USA

    USGS Publications Warehouse

    Reynolds, R.L.; Yount, J.C.; Reheis, M.; Goldstein, H.; Chavez, P., Jr.; Fulton, R.; Whitney, J.; Fuller, C.; Forester, R.M.

    2007-01-01

    The interactions between playa hydrology and playa-surface sediments are important factors that control the type and amount of dust emitted from playas as a result of wind erosion. The production of evaporite minerals during evaporative loss of near-surface ground water results in both the creation and maintenance of several centimeters or more of loose sediment on and near the surfaces of wet playas. Observations that characterize the texture, mineralogic composition and hardness of playa surfaces at Franklin Lake, Soda Lake and West Cronese Lake playas in the Mojave Desert (California), along with imaging of dust emission using automated digital photography, indicate that these kinds of surface sediment are highly susceptible to dust emission. The surfaces of wet playas are dynamic - surface texture and sediment availability to wind erosion change rapidly, primarily in response to fluctuations in water-table depth, rainfall and rates of evaporation. In contrast, dry playas are characterized by ground water at depth. Consequently, dry playas commonly have hard surfaces that produce little or no dust if undisturbed except for transient silt and clay deposited on surfaces by wind and water. Although not the dominant type of global dust, salt-rich dusts from wet playas may be important with respect to radiative properties of dust plumes, atmospheric chemistry, windborne nutrients and human health.

  16. Using NASA EOS in the Arabian and Saharan Deserts to Examine Dust Particle Size and Spectral Signature of Aerosols

    NASA Astrophysics Data System (ADS)

    Brenton, J. C.; Keeton, T.; Barrick, B.; Cowart, K.; Cooksey, K.; Florence, V.; Herdy, C.; Luvall, J. C.; Vasquez, S.

    2012-12-01

    Exposure to high concentrations of airborne particulate matter can have adverse effects on the human respiratory system. Ground-based studies conducted in Iraq have revealed the presence of potential human pathogens in airborne dust. According to the Environmental Protection Agency (EPA), airborne particulate matter below 2.5μm (PM2.5) can cause long-term damage to the human respiratory system. Given the relatively high incidence of new-onset respiratory disorders experienced by US service members deployed to Iraq, this research offers a new glimpse into how satellite remote sensing can be applied to questions related to human health. NASA's Earth Observing System (EOS) can be used to determine spectral characteristics of dust particles, the depth of dust plumes, as well as dust particle sizes. Comparing dust particle size from the Sahara and Arabian Deserts gives insight into the composition and atmospheric transport characteristics of dust from each desert. With the use of NASA SeaWiFS DeepBlue Aerosol, dust particle sizes were estimated using Angström exponent. Brightness Temperature Difference (BTD) equation was used to determine the distribution of particle sizes, the area of the dust storm, and whether silicate minerals were present in the dust. The Moderate-resolution Imaging Spectroradiometer (MODIS) on Terra satellite was utilized in calculating BTD. Minimal research has been conducted on the spectral characteristics of airborne dust in the Arabian and Sahara Deserts. Mineral composition of a dust storm that occurred 17 April 2008 near Baghdad was determined using imaging spectrometer data from the Jet Propulsion Laboratory Spectral Library and EO-1 Hyperion data. Mineralogy of this dust storm was subsequently compared to that of a dust storm that occurred over the Bodélé Depression in the Sahara Desert on 7 June 2003.

  17. Desert Dust Layers Over Polluted Marine Boundary Layers: ACE-2 Measurements and ACE-Asia Plans

    NASA Technical Reports Server (NTRS)

    Russell, Philip B.; Schmid, B.; Livingston, J. M.; Redemann, J.; Bergstrom, R. W.; Condon, Estelle P. (Technical Monitor)

    2000-01-01

    Aerosols in ACE-Asia are expected to have some commonalties with those in ACE-2, along with important differences. Among the commonalities are occurrences of desert dust layers over polluted marine boundary layers. Differences include the nature of the dust (yellowish in the East Asia desert outflow, vs. reddish-brown in the Sahara Outflow measured in ACE-2) and the composition of boundary-layer aerosols (e.g., more absorbing, soot and organic aerosol in-the Asian plume, caused by coal and biomass burning, with limited controls). In this paper we present ACE-2 measurements and analyses as a guide to our plans for ACE-2 Asia. The measurements include: (1) Vertical profiles of aerosol optical depth and extinction (380-1558 nm), and of water vapor column and concentration, from the surface through the elevated desert dust, measured by the 14-channel Ames Airborne Tracking Sunphotometer (AATS-14); (2) Comparisons of airborne and shipborne sunphotometer optical depths to satellite-retrieved values, with and without desert dust; (3) Comparisons between airborne Sunphotometer optical depth and extinction spectra and those derived from coincident airborne in situ measurements of aerosol size distribution, scattering and absorption; (4) Comparisons between size distributions measured in situ and retrieved from sunphotometer optical depth spectra; (5) Comparisons between aerosol single scattering albedo values obtained by several techniques, using various combinations of measurements of backscatter, extinction, size distribution, scattering, absorption, and radiative flux. We show how analyses of these data can be used to address questions important to ACE-Asia, such as: (1) How do dust and other absorbing aerosols affect the accuracy of satellite optical depth retrievals? How important are asphericity effects? (2) How important are supermicron dust and seasalt aerosols to overall aerosol optical depth and radiative forcing? How well are these aerosols sampled by aircraft

  18. The global dispersion of microorganisms and pollutants in clouds of desert dust

    NASA Astrophysics Data System (ADS)

    Griffin, D. W.; Kellogg, C. A.; Garrison, V. H.; Kubilay, N.; Kocak, M.; Shinn, E.

    2003-12-01

    A current estimate of the quantity of dust that is transported some distance in Earth's atmosphere each year is approximately two billion metric tons. Whereas various research projects have been undertaken to understand this planetary process, little has been done to address public and ecosystem health issues. Our research group is currently investigating long-range transport of microorganisms associated with desert dust clouds at various points on the globe via the integration of remote sensing, modeling and microbiological assays. Using a suite of molecular biology techniques, we are identifying cultivable bacteria and fungi and enumerating total bacteria and viruses. Research results indicate that approximately 30% of the microorganisms found in Earth's atmosphere during `African dust events' are species of bacteria or fungi that have previously been identified as disease causing agents in terrestrial plants, trees, and animals. This presentation will cover historical research in this field and the implications of microbial and pollutant \\(metals, pesticides, etc.\\) transport to downwind ecosystems.

  19. Wind barriers suppress fugitive dust and soil-derived airborne particles in arid regions

    SciTech Connect

    Grantz, D.A.; Vaughn, D.L.; Farber, R.J.; Kim, B.; Ashbaugh, L.; Van Curen, T.; Campbell, R.

    1998-07-01

    Areas of abandoned agricultural land in the Antelope Valley, western Mojave (high) desert of California have proven in the previous studies to be recalcitrant to conventional tillage and revegetation strategies designed to suppress wind erosion of soil and transport of sediment and fugitive dust. These areas represented a continuing source of drifting sand and of coarse and respirable suspended particulate matter. The traditional techniques failed because furrows collapsed and the water holding capacity of the overburden was too low to support seed germination and transplant survival. In this study a variety of wind barriers were evaluated for suppression of sediment transport. Airborne particles were measured with an array of coarse particle samplers at heights of 0.2, 1.0, and 2.0 m above the soil surface. Discrete artificial wind barriers, consisting of widely spaced roughness elements were effective in suppressing fugitive emissions. Wind fences established along the leeward edge of an area of blowing sand, perpendicular to the prevailing wind, significantly decreased fugitive emissions. Control was greatest and precision of the measurements was highest under high wind conditions. These techniques provide rapid and effective suppression of fugitive emissions of soil-derived particles under conditions that resist conventional tillage and revegetation techniques. A simple, indirect procedure for determining local wind velocity erosion thresholds requiring only sampling of wind run and suspended particulate mass compared favorably with direct measurement of saltation as a function of wind velocity.

  20. Evaluation of long-range transport and deposition of desert dust with the CTM MOCAGE

    NASA Astrophysics Data System (ADS)

    Martet, M.; Peuch, V.-H.; Laurent, B.; Marticorena, B.; Bergametti, G.

    2009-04-01

    Desert dust modelling and forecasting attract growing interest, due to the numerous impacts of dusts on climate, numerical weather prediction, health, ecosystems, transportation, as well as on many industrial activities. The validation of numerical tools is a very important activity in this context, and we present here an example of such an effort, combining in situ (horizontal visibility in SYNOP messages, IMPROVE database) and remote-sensing data (satellite imagery, AERONET aerosol optical thickness data). Interestingly, these measurements are available routinely, and not only in the context of dedicated measurements campaign; thus, they can be used in an operational context to monitor the performances of operational forecasting systems. MOCAGE is the chemistry-transport model of Météo-France, used operationally to forecast the three-dimensional transport of dusts and their deposition. Two very long-range transport episodes of dust have been studied: one case of Saharan dust transported to East America through Asia and Pacific observed in November 2004 and one case of Saharan dust transported from West Africa to Caribbean Islands in May 2007. Episodes of geographical extension had seldom been studied, and they provide a very selective reference to compare the modelled desert dusts with. The representation of dusts in MOCAGE appears to be realistic in these two very different cases. In turn, the model simulations are used to make the link between the complementary information provided by the different measurements tools, providing a fully consistent picture of the entire episodes. The evolution of the aerosol size distribution during the episodes has also been studied. With no surprise, our study underlines that deposition processes are very sensitive to the size of dust particles. If the atmospheric cycle, in terms of mass, is very much under the influence of larger particles (some micrometres and above), only the finer particles actually travel over thousands

  1. High concentrations of regional dust from deserts to plains across the central Rocky Mountains, USA

    NASA Astrophysics Data System (ADS)

    Reynolds, R. L.; Munson, S. M.; Fernandez, D. P.; Neff, J. C.

    2015-12-01

    Regional mineral dust in the American Southwest affects snow-melt rates, biogeochemical cycling, visibility, and public health. We measured total suspended particulates (TSP) across a 500-km-long sampling network of five remote sites in Utah and Colorado, USA, forming a gradient in distance from major dust emitting areas. The two westernmost sites on the Colorado Plateau desert had similar TSP concentrations (2008-2012, daily average=126 μg m-3; max. daily average over a two-week period=700 μg m-3 at Canyonlands National Park, Utah), while the easternmost High Plains site, close to cropped and grazed areas in northeastern Colorado, had an average concentration of 143 μg m-3 in 2011-2012 (max. daily average=656 μg m-3). Such concentrations rank comparably with those of TSP in several African and Asian cities in the paths of frequent dust storms. Dust loadings at the two intervening montane sites decreased from the western slope of the Rocky Mountains (Telluride, daily average=68 μg m-3) to an eastern site (Niwot Ridge, daily average=58 μg m-3). Back-trajectory analyses and satellite retrievals indicated that the three westernmost sites received most dust from large desert-source regions as far as 300 km to their southwest. These sources also sometimes sent dust to the two easternmost sites, which additionally captured dust from sources north and northwest of the central Rocky Mountains as well as locally at the Plains site. The PM10 fraction accounted for <15% of TSP, but most TSP is only slightly larger (typical median size, 15-20 μm) after about 100-800 km transport distances. Correlations between TSP and PM10 values indicate increases in both fractions during regional wind storms, especially related to Pacific frontal systems during late winter to late spring. These measurements and observations indicate that most dust deposition and associated air-quality problems in the interior American West are connected to regional dust sources and not to those in

  2. The Challenge of Modelling the Meteorology of Dust Emission: Lessons Learned from the Desert Storms Project

    NASA Astrophysics Data System (ADS)

    Knippertz, Peter; Marsham, John H.; Cowie, Sophie; Fiedler, Stephanie; Heinold, Bernd; Jemmett-Smith, Bradley; Pantillon, Florian; Schepanski, Kerstin; Roberts, Alexander; Pope, Richard; Gilkeson, Carl; Hubel, Eva

    2016-04-01

    Mineral dust plays an important role in the Earth system, but a reliable quantification of the global dust budget is still not possible due to a lack of observations and insufficient representation of relevant processes in climate and weather models. Five years ago, the Desert Storms project funded by the European Research Council set out to reduce these uncertainties. Its aims were to (1) improve the understanding of key meteorological mechanisms of peak wind generation in dust emission regions (particularly in northern Africa), (2) assess their relative importance, (3) evaluate their representation in models, (4) determine model sensitivities with respect to resolution and model physics, and (5) explore the usefulness of new approaches for model improvements. Here we give an overview of the most significant findings: (1) The morning breakdown of nocturnal low-level jets is an important emission mechanism, but details depend crucially on nighttime stability, which is often badly handled by models. (2) Convective cold pools are a key control on summertime dust emission over northern Africa, directly and through their influence on the heat low; they are severely misrepresented by models using parameterized convection. A new scheme based on downdraft mass flux has been developed that can mitigate this problem. (3) Mobile cyclones make a relatively unimportant contribution, except for northeastern Africa in spring. (4) A new global climatology of dust devils identifies local hotspots but suggests a minor contribution to the global dust budget in contrast to previous studies. A new dust-devil parameterization based on data from large-eddy simulations will be presented. (5) The lack of sufficient observations and misrepresentation of physical processes lead to a considerable uncertainty and biases in (re)analysis products. (6) Variations in vegetation-related surface roughness create small-scale wind variability and support long-term dust trends in semi-arid areas.

  3. The Challenge of Modeling the Meteorology of Dust Emission: Lessons Learned from the Desert Storms Project

    NASA Astrophysics Data System (ADS)

    Knippertz, P.; Marsham, J. H.; Cowie, S. M.; Fiedler, S.; Heinold, B.; Jemmett-Smith, B. C.; Pantillon, F.; Schepanski, K.; Roberts, A. J.; Pope, R.; Gilkeson, C. A.; Hubel, E.

    2015-12-01

    Mineral dust plays an important role in the Earth system, but a reliable quantification of the global dust budget is still not possible due to a lack of observations and insufficient representation of relevant processes in climate and weather models. Five years ago, the Desert Storms project funded by the European Research Council set out to reduce these uncertainties. Its aims were to (1) improve the understanding of key meteorological mechanisms of peak wind generation in dust emission regions (particularly in northern Africa), (2) assess their relative importance, (3) evaluate their representation in models, (4) determine model sensitivities with respect to resolution and model physics, and (5) explore the usefulness of new approaches for model improvements. Here we give an overview of the most significant findings: (1) The morning breakdown of nocturnal low-level jets is an important emission mechanism, but details depend crucially on nighttime stability, which is often badly handled by models. (2) Convective cold pools are a key control on summertime dust emission over northern Africa, directly and through their influence on the heat low; they are severely misrepresented by models using parameterized convection. A new scheme based on downdraft mass flux has been developed that can mitigate this problem. (3) Mobile cyclones make a relatively unimportant contribution, except for northeastern Africa in spring. (4) A new global climatology of dust devils identifies local hotspots but suggests a minor contribution to the global dust budget in contrast to previous studies. A new dust-devil parameterization based on data from large-eddy simulations will be presented. (5) The lack of sufficient observations and misrepresentation of physical processes lead to a considerable uncertainty and biases in (re)analysis products. (6) Variations in vegetation-related surface roughness create small-scale wind variability and support long-term dust trends in semi-arid areas.

  4. Inter-annual changes of Biomass Burning and Desert Dust and their impact over East Asia

    NASA Astrophysics Data System (ADS)

    DONG, X.; Fu, J. S.; Huang, K.

    2014-12-01

    Impact of mineral dust and biomass burning aerosols on air quality has been well documented in the last few decades, but the knowledge about their interactions with anthropogenic emission and their impacts on regional climate is very limited (IPCC, 2007). While East Asia is greatly affected by dust storms in spring from Taklamakan and Gobi deserts (Huang et al., 2010; Li et al., 2012), it also suffers from significant biomass burning emission from Southeast Asia during the same season. Observations from both surface monitoring and satellite data indicated that mineral dust and biomass burning aerosols may approach to coastal area of East Asia simultaneously, thus have a very unique impact on the local atmospheric environment and regional climate. In this study, we first investigated the inter-annual variations of biomass burning and dust aerosols emission for 5 consecutive years from 2006-2010 to estimate the upper and lower limits and correlation with meteorology conditions, and then evaluate their impacts with a chemical transport system. Our preliminary results indicated that biomass burning has a strong correlation with precipitation over Southeast Asia, which could drive the emission varying from 542 Tg in 2008 to 945 Tg in 2010, according to FLAMBE emission inventory (Reid et al., 2009). Mineral dust also demonstrated a strong dependence on wind filed. These inter-annual/annual variations will also lead to different findings and impacts on air quality in East Asia. Reference: Huang, K., et al. (2010), Mixing of Asian dust with pollution aerosol and the transformation of aerosol components during the dust storm over China in spring 2007, Journal of Geophysical Research-Atmospheres, 115. IPCC (2007), Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, New York. Li, J., et al. (2012), Mixing of Asian mineral dust with anthropogenic pollutants over East Asia: a model case study of a super-duststorm in

  5. Technical Note: Optical properties of desert dust with non-spherical particles: data incorporated to OPAC

    NASA Astrophysics Data System (ADS)

    Koepke, P.; Gasteiger, J.; Hess, M.

    2015-02-01

    Mineral desert dust particles in general are no spheres and assuming spherical particles, instead of more realistic shapes, has significant effects on modeled optical dust properties and so on the belonging remote sensing procedures for desert dust and the derived radiative forcing. Thus in a new version of the data base OPAC (Optical Properties of Aerosols and Clouds; Hess et al., 1998), the optical properties of the mineral particles are modeled describing the particles as spheroids with size dependent aspect ratio distributions, but with the size distributions and the spectral refractive indices not changed against the previous version of OPAC. The spheroid assumption strongly improves the scattering functions, but pays regard to the limited knowledge on particle shapes in an actual case. The relative deviations of the phase functions of non-spherical mineral particles from those of spherical particles are up to +60% at scattering angles of about 130° and up to -60% in the backscatter region, but the deviations are generally small for optical properties that are independent of the scattering angle. The improved version of OPAC (4.0) is freely available under http://www.rascin.net/

  6. Satellite-based retrieval of desert dust deposition into the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Jaeger, Malte; Lelli, Luca; Vountas, Marco; Burrows, John P.

    2015-04-01

    Desert dust plays a prominent role in climate as it influences the radiation budget in the atmosphere and, if being transported to the ocean, affects the ecosystem, e.g. by acting as fertilizer. Measurements of dust deposition are usually performed using collectors on land and on buoys as well as sediment traps deployed across the Atlantic Ocean. However, regional to continental coverage can be only achieved with satellites. We present a new methodology for the assessment of desert dust deposition from top-of-atmosphere reflected solar irradiance measured by satellite. This methodology is based on the observation of changes in columnar aerosol optical thickness (AOT) along the transport path of dust outflows from the Sahara. The guiding idea is that, if transport orientation is correctly estimated, a decrease in AOT across the Atlantic can be linked to the deposition of aerosols onto the ocean surface. The Bremen Aerosol Retrieval (BAER), developed at the Institute of Environmental Physics of University of Bremen (IUP/U-Bre), serves as primary AOT retrieval algorithm. It uses multispectral measurements by the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and MEdium Resolution Imaging Spectrometer (MERIS). Especially the correct implementation of the wind fields for trajectory prediction and the choice of comparison sites are of critical importance for deposition estimation. Therefore a two-step wind correction, including a simple implementation of vertical dust layer structure and wind variation, is performed, using ECMWF reanalysis data. First tests show that seasonal patterns of AOT are correctly reproduced, both in space and time. For example the largest peak in AOT mass loss is observed at summer. Moreover, intercomparisons with in-situ sedimentation measurements at various sites show good correlations.

  7. What is the impact of Harmattan surges on desert dust emission in North Africa?

    NASA Astrophysics Data System (ADS)

    Fiedler, Stephanie; Kaplan, Michael L.; Knippertz, Peter

    2015-04-01

    Desert dust aerosols have important implications in the Earth system, but their emission amount has a large model uncertainty. Improving the most important meteorological processes for dust-emitting winds helps to reduce this uncertainty. However, the dominant meteorological mechanisms for the large dust emission during spring remain unclear. This time of year is characterized by mobile, long-lived cyclones and Harmattan surges which are capable to uplift dust aerosol for long-range atmospheric transport. Emission near to the centre of mobile, long-lived cyclones are associated with a small mass of dust emission over the northern Sahara in spring, despite their most frequent occurrence in this season. Harmattan surges are proposed to be more efficient in emitting dust aerosol in spring. These events manifest themselves as a postfrontal strengthening of near-surface winds with a continental impact on dust emission. The present study shows the first long-term climatology of dust emission associated with Harmattan surges over North Africa. Using a newly-developed automated identification, Harmattan surges are statistically analysed in 32 years of ERA-Interim re-analysis from the European Centre for Medium-Range Weather Forecasts. The results show 34 events per year in the annual mean. Spring is herein the most active season with the largest mean number and duration of Harmattan surges, in contrast to summer with virtually no activity. The offline dust emission model by Tegen et al (2002) is used to calculate emissions with ERA-Interim data. Combining these results with the Harmattan surges allows a first quantitative estimate of the associated emission mass. The results highlight that a fraction of 32 % of the total emission is associated with these events, annually and spatially averaged across North Africa. This amount exceeds the annual mean contribution of nocturnal low-level jets to dust emission, which is known as one of the most important drivers for North

  8. Runoff quality impacts of dust suppression using saline water

    NASA Astrophysics Data System (ADS)

    Loch, Rob J.; Squires, Helen

    2010-05-01

    In mining and gas operations, dust generation from unsealed roads is a major problem. Commonly, road watering is used to suppress dust, with the lowest water quality available generally being selected for that purpose. Whilst minimising water usage for the site, that practice does create concerns with respect to potential environmental impacts if runoff from the treated roads has significantly elevated salinity. For coal seam gas operations, the water extracted concurrently with the gas contains predominantly sodium bicarbonate. Therefore, where coal seam gas water is sprayed onto roads, there is potential for elevated sodium in runoff to impact on soil adjoining the roads, but there is no information on the rates of dissolution and mobilisation of soluble salt from the surface of roads that have been sprayed with low quality water to reduce dust. Therefore a rainfall simulator study was carried out to investigate rates of mobilisation of sodium bicarbonate from compacted soil surfaces simulating an unsealed road. The study considered effects of the amount of precipitated sodium bicarbonate on the soil surface and variations in rainfall intensity. Because the soil surfaces were compacted, runoff commenced almost immediately following application of rain. For all treatments with applied surface salt, runoff quality data showed a peak in salt concentration in the first flush of runoff, and relatively rapid reduction through time in those initial concentrations. The magnitude and duration of peak concentrations depended on both rainfall rate and the quantity of salt present on the soil surface. The flush of salts in run-off from the roads occurred very early in the run-off event, when none of the surrounding area would have commenced to run off. Consequently, the relatively small volume of run-off produced directly by the road could be expected to predominantly infiltrate in the table drain adjoining the road. The initial flush of saline water would then be leached to

  9. Direct radiative effects induced by intense desert dust outbreaks over the broader Mediterranean basin

    NASA Astrophysics Data System (ADS)

    Gkikas, Antonis; Obiso, Vincenzo; Vendrell, Lluis; Basart, Sara; Jorba, Oriol; Pérez Garcia-Pando, Carlos; Hatzianastassiou, Nikos; Gassó, Santiago; Baldasano, Jose Maria

    2016-04-01

    Throughout the year, under favorable conditions, massive loads of mineral particles originating in the northern African and Middle East deserts are transported over the Mediterranean basin. Due to their composition and size, dust aerosols perturb the Earth-Atmosphere system's energy budget interacting directly with the shortwave (SW) and longwave (LW) radiation. The present study aims to compute the Mediterranean dust outbreaks' direct radiative effects (DREs) as well as to assess the effect of including dust DREs in numerical simulations of a regional model. To this aim, 20 intense dust outbreaks have been selected based on their spatial coverage and intensity. Their identification, over the period 2000-2013, has been achieved through an objective and dynamic algorithm which utilizes as inputs daily satellite retrievals derived by the MODIS-Terra, EP-TOMS and OMI-Aura sensors. For each outbreak, two simulations of the NMMB/BSC-Dust model were made for a forecast period of 84 hours, with the model initialized at 00 UTC of the day when the dust outbreak was ignited, activating (RADON) and deactivating (RADOFF) dust-radiation interactions. The simulation domain covers the northern Africa, the Middle East and Europe at 0.25° x 0.25° horizontal resolution, for 40 hybrid sigma pressure levels up to 50 hPa. The instantaneous and regional DREs have been calculated at the top of the atmosphere (TOA), into the atmosphere (ATMAB), and at surface, for the downwelling (SURF) and the absorbed (NETSURF) radiation, for the SW, LW and NET (SW+LW) radiation. The interaction between dust aerosols and NET radiation, locally leads to an atmospheric warming (DREATMAB) by up to 150 Wm-2, a surface cooling (DRENETSURF) by up to 250 Wm-2 and a reduction of the downwelling radiation at the surface (DRESURF) by up to 300 Wm-2. At TOA, DREs are mainly negative (down to -150 Wm-2) indicating a cooling of the Earth-Atmosphere system, although positive values (up to 50 Wm-2) are encountered

  10. Sunlight Transmission through Desert Dust and Marine Aerosols: Diffuse Light Corrections to Sun Photometry and Pyrheliometry

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Livingston, J. M.; Dubovik, O.; Ramirez, S. A.; Wang, J.; Redemann, J.; Schmid, B.; Box, M.; Holben, B. N.

    2003-01-01

    Desert dust and marine aerosols are receiving increased scientific attention because of their prevalence on intercontinental scales and their potentially large effects on Earth radiation and climate, as well as on other aerosols, clouds, and precipitation. The relatively large size of desert dust and marine aerosols produces scattering phase functions that are strongly forward- peaked. Hence, Sun photometry and pyrheliometry of these aerosols are more subject to diffuse-light errors than is the case for smaller aerosols. Here we quantify these diffuse-light effects for common Sun photometer and pyrheliometer fields of view (FOV), using a data base on dust and marine aerosols derived from (1) AERONET measurements of sky radiance and solar beam transmission and (2) in situ measurements of aerosol layer size distribution and chemical composition. Accounting for particle non-sphericity is important when deriving dust size distribution from both AERONET and in situ aerodynamic measurements. We express our results in terms of correction factors that can be applied to Sun photometer and pyrheliometer measurements of aerosol optical depth (AOD). We find that the corrections are negligible (less than approximately 1% of AOD) for Sun photometers with narrow FOV (half-angle eta less than degree), but that they can be as large as 10% of AOD at 354 nm wavelength for Sun photometers with eta = 1.85 degrees. For pyrheliometers (which can have eta up to approximately 2.8 degrees), corrections can be as large as 16% at 354 nm. We find that AOD correction factors are well correlated with AOD wavelength dependence (hence Angstrom exponent). We provide best-fit equations for determining correction factors from Angstrom exponents of uncorrected AOD spectra, and we demonstrate their application to vertical profiles of multiwavelength AOD.

  11. Mediterranean desert dust outbreaks and their vertical structure based on remote sensing data

    NASA Astrophysics Data System (ADS)

    Gkikas, A.; Basart, S.; Hatzianastassiou, N.; Marinou, E.; Amiridis, V.; Kazadzis, S.; Pey, J.; Querol, X.; Jorba, O.; Gassó, S.; Baldasano, J. M.

    2015-10-01

    The main aim of the present study is to describe the vertical structure of the intense Mediterranean dust outbreaks, based on the use of satellite and surface-based retrievals/measurements. Strong and extreme desert dust (DD) episodes are identified at 1° × 1° spatial resolution, over the period March 2000-February 2013, through the implementation of an updated objective and dynamic algorithm. According to the algorithm, strong DD episodes occurring at a specific place correspond to cases in which the daily aerosol optical depth at 550 nm (AOD550 nm) exceeds or equals the long-term mean AOD550 nm (Mean) plus two standard deviations (SD) value being smaller than Mean + 4 · SD. Extreme DD episodes correspond to cases in which the daily AOD550 nm value equals or exceeds Mean + 4 · SD. For the identification of DD episodes additional optical properties (Ångström exponent, fine fraction, effective radius and Aerosol Index) derived by the MODIS-Terra & Aqua (also AOD retrievals), OMI-Aura and EP-TOMS databases are used as inputs. According to the algorithm using MODIS-Terra data, over the period March 2000-February 2013, strong DD episodes occur more frequently (up to 9.9 episodes yr-1) over the western Mediterranean while the corresponding frequencies for the extreme ones are smaller (up to 3.3 episodes yr-1, central Mediterranean Sea). In contrast to their frequency, dust episodes are more intense (AODs up to 4.1), over the central and eastern Mediterranean Sea, off the northern African coasts. Slightly lower frequencies and higher intensities are found when the satellite algorithm operates based on MODIS-Aqua retrievals, for the period 2003-2012. The performance of the satellite algorithm is assessed against surface-based daily data from 109 sun-photometric (AERONET) and 22 PM10 stations. The agreement between AERONET and MODIS AOD is satisfactory (R = 0.505 - 0.75) improving considerably when MODIS level 3 retrievals with higher sub-grid spatial

  12. Can desert dust explain the outgoing longwave radiation anomaly over the Sahara during July 2003?

    NASA Astrophysics Data System (ADS)

    Haywood, Jim M.; Allan, Richard P.; Culverwell, Ian; Slingo, Tony; Milton, Sean; Edwards, John; Clerbaux, Nicolas

    2005-03-01

    Measurements of the top-of-the-atmosphere outgoing longwave radiation (OLR) for July 2003 from Meteosat-7 are used to assess the performance of the numerical weather prediction version of the Met Office Unified Model. A significant difference is found over desert regions of northern Africa where the model emits too much OLR by up to 35 Wm-2 in the monthly mean. By cloud-screening the data we find an error of up to 50 Wm-2 associated with cloud-free areas, which suggests an error in the model surface temperature, surface emissivity, or atmospheric transmission. By building up a physical model of the radiative properties of mineral dust based on in situ, and surface-based and satellite remote sensing observations we show that the most plausible explanation for the discrepancy in OLR is due to the neglect of mineral dust in the model. The calculations suggest that mineral dust can exert a longwave radiative forcing by as much as 50 Wm-2 in the monthly mean for 1200 UTC in cloud-free regions, which accounts for the discrepancy between the model and the Meteosat-7 observations. This suggests that inclusion of the radiative effects of mineral dust will lead to a significant improvement in the radiation balance of numerical weather prediction models with subsequent improvements in performance.

  13. Environmental Sequencing of Biotic Components of Dust in the Chihuahuan Desert

    NASA Astrophysics Data System (ADS)

    Walsh, E.; Gill, T. E.; Rivas, J. A., Jr.; Leung, M. Y.; Mohl, J.

    2015-12-01

    A growing number of studies mark the role of wind in dispersing biota. Most of these approaches have used traditional methods to assess taxonomic diversity. Here we used next generation sequencing to characterize microbiota in dust collected from the Chihuahuan Desert. Atmospheric dust was collected during events during 2011-2014 using dry deposition collectors placed at two sites in El Paso Co., TX. In parallel experiments, we rehydrated subsamples of dust and conducted PCR amplifications using conserved primers for 16S and 18S ribosomal genes. Sequenced reads were de-multiplexed, quality filtered, and processed using QIIME. Taxonomy was assigned based on pairwise identity using BLAST for microbial eukaryotes. All samples were rarefied to a set number of sequences per sample prior to downstream analyses. Bioinformatic analysis of four of the dust samples yielded a diversity of biota, including zooplankton, bacteria, fungi, algae, and protists, but fungi predominate (>90% of both 10K and 3K reads). In our rehydrations of dust samples from the U.S. southwest nematodes, gastrotrichs, tardigrades, monogonont and bdelloid rotifers, branchiopods and numerous ciliates have been recovered. Variability in genetic diversity among samples is based, in part, on the source and extent of the particular dust event. We anticipate the same patterns will be seen in the complete data set. These preliminary results indicate that wind is a major transporter of not only fungi, bacteria and other unicellular organisms but may also be important in shaping the distribution patterns of multi-cellular organisms such as those that inhabit aquatic environments in the arid southwestern US.

  14. Climate change and climate systems influence and control the atmospheric dispersion of desert dust: implications for human health

    USGS Publications Warehouse

    Griffin, Dale W.

    2010-01-01

    The global dispersion of desert dust through Earth’s atmosphere is greatly influenced by temperature. Temporal analyses of ice core data have demonstrated that enhanced dust dispersion occurs during glacial events. This is due to an increase in ice cover, which results in an increase in drier terrestrial cover. A shorter temporal analysis of dust dispersion data over the last 40 years has demonstrated an increase in dust transport. Climate systems or events such as the North Atlantic Oscillation, the Indian Ocean subtropical High, Pacific Decadal Oscillation, and El Nino-Sothern Oscillation are known to influence global short-term dust dispersion occurrence and transport routes. Anthropogenic influences on dust transport include deforestation, harmful use of topsoil for agriculture as observed during the American Dust Bowl period, and the creation of dry seas (Aral Sea) and lakes (Lake Owens in California and Lake Chad in North Africa) through the diversion of source waters (for irrigation and drinking water supplies). Constituents of desert dust both from source regions (pathogenic microorganisms, organic and inorganic toxins) and those scavenged through atmospheric transport (i.e., industrial and agricultural emissions) are known to directly impact human and ecosystem health. This presentation will present a review of global scale dust storms and how these events can be both a detriment and benefit to various organisms in downwind environments.

  15. Impact of desert dust on the biogeochemistry of phosphorus in terrestrial ecosystems

    NASA Astrophysics Data System (ADS)

    Okin, Gregory S.; Mahowald, Natalie; Chadwick, Oliver A.; Artaxo, Paulo

    2004-06-01

    Leaching, biomass removal, and partitioning of phosphorus (P) into reservoirs not available to plants can limit the long-term productivity of terrestrial ecosystems. We evaluate the importance of atmospheric P inputs to the world's soils by estimating the total soil P turnover time with respect to dustborne P additions. Estimated turnover times range from ˜104 to ˜107 years. Our estimates provide a unique perspective on the importance and patterns of aeolian deposition to terrestrial landscapes. Dust source regions are areas of intense soil P cycling on large scales, but are too water-limited for this rapid cycling to have a major influence on ecosystem dynamics. By contrast, semiarid desert margins receive significant aeolian P from neighboring deserts and are likely influenced by dustborne P additions for the long-term maintenance of productivity. This is particularly true for the semiarid steppes of Africa and Eurasia. The prevalence of large dust sources in Africa and Eurasia indicates that these areas may generally be more influenced by dustborne P additions than soils in the Americas. Significant western hemisphere exceptions to this pattern occur on very old landscapes, such as the forests of the southeastern United States and the Amazon Basin. The Amazon Basin is highly dependent on aeolian deposition for the maintenance of long-term productivity. Dust deposition to terrestrial environments has not been constant with time. Variability in past P deposition related to geologically recent climate change may provide the strongest controls on present and future soil P in the Amazon and elsewhere.

  16. Influence of Desert Dust Intrusions on Ground-based and Satellite Derived Ultraviolet Irradiance in Southeastern Spain

    NASA Technical Reports Server (NTRS)

    Krotkov, Nickolay A.; Anton, Manuel; Valenzuela, Antonio; Roman, Roberto; Lyamani, Hassan; Arola, Antti; Olmo, Francisco J.; Alados-Arboledas

    2012-01-01

    The desert dust aerosols strongly affect propagation of solar radiation through the atmosphere, reducing surface irradiance available for photochemistry and photosynthesis. This paper evaluates effects of desert dust on surface UV erythemal irradiance (UVER), as measured by a ground-based broadband UV radiometer and retrieved from the satellite Ozone Monitoring Instrument (OMI) at Granada (southern Spain) from January 2006 to December 2010. The dust effects are characterized by the transmittance ra tio of the measured UVER to the corresponding modeled clear sky value. The transmittance has an exponential dependency on aerosol optical depth (AOD), with minimum values of approximately 0.6 (attenuation of approximately 40%). The OMI UVER algorithm does not account for UV aerosol absorption, which results in overestimation of the ground-based UVER especially during dust episodes with a mean relative difference up to 40%. The application of aerosol absorption post-correction method reduces OMI bias up to approximately 13%. The results highlight great effect of desert dust on the surface UV irradiance in regions like southern Spain, where dust intrusions from Sahara region are very frequent.

  17. Mediterranean intense desert dust outbreaks and their vertical structure based on remote sensing data

    NASA Astrophysics Data System (ADS)

    Gkikas, Antonis; Basart, Sara; Hatzianastassiou, Nikos; Marinou, Eleni; Amiridis, Vassilis; Kazadzis, Stelios; Pey, Jorge; Querol, Xavier; Jorba, Oriol; Gassó, Santiago; Baldasano, José Maria

    2016-07-01

    The main aim of the present study is to describe the vertical structure of the intense Mediterranean dust outbreaks, based on the use of satellite and surface-based retrievals/measurements. Strong and extreme desert dust (DD) episodes are identified at 1° × 1° spatial resolution, over the period March 2000-February 2013, through the implementation of an updated objective and dynamic algorithm. According to the algorithm, strong DD episodes occurring at a specific place correspond to cases in which the daily aerosol optical depth at 550 nm (AOD550 nm) exceeds or equals the long-term mean AOD550 nm (Mean) plus two standard deviations (SD), which is also smaller than Mean+4 × SD. Extreme DD episodes correspond to cases in which the daily AOD550 nm value equals or exceeds Mean+4 × SD. For the identification of DD episodes, additional optical properties (Ångström exponent, fine fraction, effective radius and aerosol index) derived by the MODIS-Terra & Aqua (also AOD retrievals), OMI-Aura and EP-TOMS databases are used as inputs. According to the algorithm using MODIS-Terra data, over the period March 2000-February 2013, strong DD episodes occur more frequently (up to 9.9 episodes year-1) over the western Mediterranean, while the corresponding frequencies for the extreme ones are smaller (up to 3.3 episodes year-1, central Mediterranean Sea). In contrast to their frequency, dust episodes are more intense (AODs up to 4.1), over the central and eastern Mediterranean Sea, off the northern African coasts. Slightly lower frequencies and higher intensities are found when the satellite algorithm operates based on MODIS-Aqua retrievals, for the period 2003-2012. The consistency of the algorithm is successfully tested through the application of an alternative methodology for the determination of DD episodes, which produced similar features of the episodes' frequency and intensity, with just slightly higher frequencies and lower intensities. The performance of the

  18. Application of wind-profiling radar data to the analysis of dust weather in the Taklimakan Desert.

    PubMed

    Wang, Minzhong; Wei, Wenshou; Ruan, Zheng; He, Qing; Ge, Runsheng

    2013-06-01

    The Urumqi Institute of Desert Meteorology of the China Meteorological Administration carried out an atmospheric scientific experiment to detect dust weather using a wind-profiling radar in the hinterland of the Taklimakan Desert in April 2010. Based on the wind-profiling data obtained from this experiment, this paper seeks to (a) analyze the characteristics of the horizontal wind field and vertical velocity of a breaking dust weather in a desert hinterland; (b) calculate and give the radar echo intensity and vertical distribution of a dust storm, blowing sand, and floating dust weather; and (c) discuss the atmosphere dust counts/concentration derived from the wind-profiling radar data. Studies show that: (a) A wind-profiling radar is an upper-air atmospheric remote sensing system that effectively detects and monitors dust. It captures the beginning and ending of a dust weather process as well as monitors the sand and dust being transported in the air in terms of height, thickness, and vertical intensity. (b) The echo intensity of a blowing sand and dust storm weather episode in Taklimakan is about -1~10 dBZ while that of floating dust -1~-15 dBZ, indicating that the dust echo intensity is significantly weaker than that of precipitation but stronger than that of clear air. (c) The vertical shear of horizontal wind and the maintenance of low-level east wind are usually dynamic factors causing a dust weather process in Taklimakan. The moment that the low-level horizontal wind field finds a shear over time, it often coincides with the onset of a sand blowing and dust storm weather process. (d) When a blowing sand or dust storm weather event occurs, the atmospheric vertical velocity tends to be of upward motion. This vertical upward movement of the atmosphere supported with a fast horizontal wind and a dry underlying surface carries dust particles from the ground up to the air to form blown sand or a dust storm. PMID:23099859

  19. Paleoclimatic tracers: An investigation using an atmospheric general circulation model under ice age conditions. 1. Desert dust

    SciTech Connect

    Joussaume, S. )

    1993-02-20

    Many studies with atmospheric general circulation models (AGCMs) have demonstrated their usefulness in reconstructing past climates. In a new approach, the author has used an AGCM to investigate the link between tracer cycles and climate. He considers in this paper the atmospheric cyle of windblown dust material from desertic areas and in part 2 the water isotope cycles. Studies from ice cores have shown a strong increase of the dust deposits during glacial periods, both over East Antarctica and Greenland. He does not know, however, whether this past increase is global or just a local feature, where the dust came from and what are the mechanisms yielding this increase. He tries to answer these questions by using an AGCM including a model for the desert dust cycle to simulate the present-day and Last Glacial Maximum climates for February and August. The model simulates only a weak increase of the global atmospheric dust content. Stronger variations are obtained at a regional scale and are in good agreement with observations from deep-sea sediments. However, the model does not reproduce the great increase of the dust concentrations in snow that has been observed in ice cores. Several model deficiencies can induce this model-data discrepancy as, for example, inaccuracies of the circulation patterns or of the dust model. However, most likely, the model fails to simulate the actual sources of dust. 73 refs., 23 figs., 5 tabs.

  20. Mediterranean intense desert dust outbreaks and their vertical structure based on remote sensing data

    NASA Astrophysics Data System (ADS)

    Gkikas, Antonis; Basart, Sara; Hatzianastassiou, Nikos; Marinou, Eleni; Amiridis, Vassilis; Kazadzis, Stelios; Pey, Jorge; Querol, Xavier; Jorba, Oriol; Gassó, Santiago; Baldasano, José Maria

    2016-07-01

    The main aim of the present study is to describe the vertical structure of the intense Mediterranean dust outbreaks, based on the use of satellite and surface-based retrievals/measurements. Strong and extreme desert dust (DD) episodes are identified at 1° × 1° spatial resolution, over the period March 2000-February 2013, through the implementation of an updated objective and dynamic algorithm. According to the algorithm, strong DD episodes occurring at a specific place correspond to cases in which the daily aerosol optical depth at 550 nm (AOD550 nm) exceeds or equals the long-term mean AOD550 nm (Mean) plus two standard deviations (SD), which is also smaller than Mean+4 × SD. Extreme DD episodes correspond to cases in which the daily AOD550 nm value equals or exceeds Mean+4 × SD. For the identification of DD episodes, additional optical properties (Ångström exponent, fine fraction, effective radius and aerosol index) derived by the MODIS-Terra & Aqua (also AOD retrievals), OMI-Aura and EP-TOMS databases are used as inputs. According to the algorithm using MODIS-Terra data, over the period March 2000-February 2013, strong DD episodes occur more frequently (up to 9.9 episodes year-1) over the western Mediterranean, while the corresponding frequencies for the extreme ones are smaller (up to 3.3 episodes year-1, central Mediterranean Sea). In contrast to their frequency, dust episodes are more intense (AODs up to 4.1), over the central and eastern Mediterranean Sea, off the northern African coasts. Slightly lower frequencies and higher intensities are found when the satellite algorithm operates based on MODIS-Aqua retrievals, for the period 2003-2012. The consistency of the algorithm is successfully tested through the application of an alternative methodology for the determination of DD episodes, which produced similar features of the episodes' frequency and intensity, with just slightly higher frequencies and lower intensities. The performance of the

  1. Novel approach for suppressing cutting dust using foam on a fully mechanized face with hard parting.

    PubMed

    Wang, Hetang; Wang, Deming; Wang, Qingguo; Jia, Zhiqiang

    2014-01-01

    The cutting dust created by the shearer drum is the main source of dust on a fully mechanized coal face. However, overexposure to respirable dust may cause pneumoconiosis in coal workers, while coal dust may lead to serious explosions. The fully mechanized face known as II1051 Face, found at the Zhuxianzhuang Coal Mine located in east China, generates dust by way of the drum on a high-power shear. The coal seam involves hard rock parting so there is a high concentration of cutting dust when the shearer is working. Thus, we developed a new foam dust suppression method with an air self-suction system based on an analysis of the dust generation characteristics that suppressed the shearer cutting dust level. The new foam system was evaluated in a field test where the dust concentration was measured at two points. The results showed that the foam reduced the cutting dust concentration significantly. The respirable dust exposure levels were reduced from 378.4 mg/m(3)to 53.5 mg/m(3)and the visibility was enhanced dramatically. Thus, we conclude that our new foam system is highly efficient at capturing cutting dust, and it has a much lower water consumption. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: Contact angle of cutting dust sample, migration trajectory of cutting dust, technological process for suppressing shearer cutting dust using foam, the layout of the foam dust suppression system on coal face, real object of the air self-suction type foam generator, the special foam nozzle used for shearers, relevant experimental results of the air self-suction foam system.]. PMID:24521065

  2. Mineralogical, chemical, and optical interrelationships of mineral dusts from desert source regions

    NASA Astrophysics Data System (ADS)

    Engelbrecht, J. P.; Moosmüller, H.; Pincock, S.; Jayanty, J.; Casuccio, G.

    2013-12-01

    The goal of the project was to provide information on the mineralogical, chemical and physical interrelationships of re-suspended mineral dust samples collected from global dust sources. Surface soil samples were previously collected from more than 64 desert sites, including the southwestern USA (12), Mali (3), Chad (3), Morocco (1), Canary Islands (8), Cape Verde (1), Djibouti (1), Afghanistan (3), Iraq (6), Kuwait (5), Qatar (1), UAE (1), Serbia (3), China (5), Namibia (3), Botswana (4), Australia (3), and Chile (1). The < 38 μm sieved fraction of each sample was re-suspended in an entrainment facility, from which the airborne mineral dust could be sampled and analyzed. Instruments integrated into the entrainment facility included two PM10 and two PM2.5 filter samplers, a beta attenuation gauge for the continuous measurement of PM10 and PM2.5 particulate mass fractions, an aerodynamic particle size (APS) analyzer, and a three wavelength (405, 532, 781nm) photoacoustic instrument with integrating reciprocal nephelometer for monitoring aerosol absorption and scattering coefficients during the re-suspension process. Filter sample media included Teflon membrane and quartz fiber filters for chemical analysis (71 species), and Nuclepore filters for individual particle analysis by Scanning Electron Microscopy (SEM). The < 38 μm sieved fractions were also analyzed by X-ray diffraction for their mineral content while the > 38 μm, < 125 μm fractions were further mineralogically characterized by optical microscopy. We will be presenting results on the optical measurements, showing the relationship between single scattering albedo (SSA) at three different wavelengths, and chemical as well as mineralogical content and interrelationships, of the entrained dust samples. Information from this data base will be available for research in global climate, remote sensing, visibility, and health (medical geology).

  3. The strongest desert dust intrusion mixed with smoke over the Iberian Peninsula registered with Sun photometry

    NASA Astrophysics Data System (ADS)

    Cachorro, V. E.; Toledano, C.; Prats, N.; Sorribas, M.; Mogo, S.; Berjón, A.; Torres, B.; Rodrigo, R.; de La Rosa, J.; de Frutos, A. M.

    2008-07-01

    We present the analysis of the strongest North African desert dust (DD) intrusion that occurred over the Iberian Peninsula (IP) during the last decade, as registered by modern remote sensing techniques like Sun photometry. This event took place from 22 July to 3 August 2004. The most relevant features of this exceptional event, originated over the Saharan desert, were its great intensity and duration. We focus on the columnar aerosol properties measured by the AERONET-Cimel photometers at El Arenosillo (southwest) and Palencia (north-center) stations. Aerosol optical depth (AOD) reached a maximum of 2.7 at El Arenosillo during 22 July and 1.3 at Palencia on 23 July, with the Ånsgtröm exponent values near zero during the AOD peaks. In addition, PM10 concentration levels are also reported at various sites of the IP in order to establish the impact of this intrusion, reaching daily values as high as 200 μg/m3 and peaks near 600 μg/m3 in an hourly basis. The interest of this special event is increased because of the mixing with smoke particles from concurrent forest fires in the IP. Features of the columnar volume particle size distribution and derived microphysical parameters, the single scattering albedo, and a reliable estimation of the radiative forcing under these extreme conditions are also reported. Complementary information, as air mass back trajectories, synoptic charts, images, and AOD maps of satellite sensors (SeaWIFS, MODIS) together with NAAPS prognostic model, is used in the analysis in order to draw a detailed scenario of this dust-smoke event over the IP.

  4. Taklimakan Desert nocturnal low-level jet: climatology and dust activity

    NASA Astrophysics Data System (ADS)

    Ge, Jin Ming; Liu, Huayue; Huang, Jianping; Fu, Qiang

    2016-06-01

    While nocturnal low-level jets (NLLJs) occur frequently in many parts of the world, the occurrence and other detailed characteristics of NLLJs over the Taklimakan Desert (TD) are not well known. This paper presents a climatology of NLLJs and coincident dust over the TD by analyzing multi-year ERA-Interim reanalysis and satellite observations. It is found that the ERA-Interim dataset can capture the NLLJs' features well by comparison with radiosonde data from two surface sites. The NLLJs occur in more than 60 % of nights, which are primarily easterly to east-northeasterly. They typically appear at 100 to 400 m above the surface with a speed of 4 to 10 m s-1. Most NLLJs are located above the nocturnal inversion during the warm season, while they are embedded in the inversion layer during the cold season. NLLJs above the inversion have a strong annual cycle with a maximum frequency in August. We also quantify the convective boundary layer (CBL) height and construct an index to measure the magnitude of the momentum in the CBL. We find that the magnitude of momentum in the lower atmosphere from the top of the surface layer to the top of mixed layer is larger for NLLJ cases than for non-NLLJ cases, and in the warm season the downward momentum transfer process is more intense and rapid. The winds below the NLLJ core to the desert surface gain strength in summer and autumn, and these summer and autumn winds are coincident with an enhancement of aerosol optical depth. This indicates that the NLLJ is an important mechanism for dust activity and transport during the warm season over the Taklimakan.

  5. Respirable Silica Dust Suppression During Artificial Stone Countertop Cutting

    PubMed Central

    Cooper, Jared H.; Johnson, David L.; Phillips, Margaret L.

    2015-01-01

    Purpose: To assess the relative efficacy of three types of controls in reducing respirable silica exposure during artificial stone countertop cutting with a handheld circular saw. Approach: A handheld worm drive circular saw equipped with a diamond segmented blade was fitted with water supply to wet the blade as is typical. The normal wetted-blade condition was compared to (i) wetted-blade plus ‘water curtain’ spray and (ii) wetted-blade plus local exhaust ventilation (LEV). Four replicate 30-min trials of 6-mm deep, 3-mm wide cuts in artificial quartz countertop stone were conducted at each condition in a 24-m3 unventilated tent. One dry cutting trial was also conducted for comparison. Respirable cyclone breathing zone samples were collected on the saw operator and analyzed gravimetrically for respirable mass and by X-ray diffraction for respirable quartz mass. Results: Mean quartz content of the respirable dust was 58.5%. The ranges of 30-min mass and quartz task concentrations in mg m−3 were as follows—wet blade alone: 3.54–7.51 and 1.87–4.85; wet blade + curtain: 1.81–5.97 and 0.92–3.41; and wet blade + LEV: 0.20–0.69 and <0.12–0.20. Dry cutting task concentrations were 69.6mg m−3 mass and 44.6mg m−3 quartz. There was a statistically significant difference (α = 0.05) between the wet blade + LEV and wet blade only conditions, but not between the wet blade + curtain and wet blade only conditions, for both respirable dust and respirable silica. Conclusions: Sawing with a wetted blade plus LEV reduced mean respirable dust and quartz task exposures by a factor of 10 compared to the wet blade only condition. We were unable to show a statistically significant benefit of a water curtain in the ejection path, but the data suggested some respirable dust suppression. PMID:25326187

  6. Remote sensing of desert dust aerosols over the Sahel : potential use for health impact studies

    NASA Astrophysics Data System (ADS)

    Deroubaix, A. D.; Martiny, N. M.; Chiapello, I. C.; Marticorena, B. M.

    2012-04-01

    Since the end of the 70's, remote sensing monitors the desert dust aerosols due to their absorption and scattering properties and allows to make long time series which are necessary for air quality or health impact studies. In the Sahel, a huge health problem is the Meningitis Meningococcal (MM) epidemics that occur during the dry season : the dust has been suspected to be crucial to understand their onsets and dynamics. The Aerosol absorption Index (AI) is a semi-quantitative index derived from TOMS and OMI observations in the UV available at a spatial resolution of 1° (1979-2005) and 0.25° (2005-today) respectively. The comparison of the OMI-AI and AERONET Aerosol Optical thickness (AOT) shows a good agreement at a daily time-step (correlation ~0.7). The comparison of the OMI-AI with the Particle Matter (PM) measurement of the Sahelian Dust Transect is lower (~0.4) at a daily time-step but it increases at a weekly time-step (~0.6). The OMI-AI reproduces the dust seasonal cycle over the Sahel and we conclude that the OMI-AI product at a 0.25° spatial resolution is suitable for health impact studies, especially at a weekly epidemiological time-step. Despite the AI is sensitive to the aerosol altitude, it provides a daily spatial information on dust. A preliminary investigation analysis of the link between weekly OMI AI and weekly WHO epidemiological data sets is presented in Mali and Niger, showing a good agreement between the AI and the onset of the MM epidemics with a constant lag (between 1 and 2 week). The next of this study is to analyse a deeper AI time series constituted by TOMS and OMI data sets. Based on the weekly ratios PM/AI at 2 stations of the Sahelian Dust Transect, a spatialized proxy for PM from the AI has been developed. The AI as a proxy for PM and other climate variables such as Temperature (T°), Relative Humidity (RH%) and the wind (intensity and direction) could then be used to analyze the link between those variables and the MM epidemics

  7. Optical properties of non-spherical desert dust particles in the terrestrial infrared - An asymptotic approximation approach

    NASA Astrophysics Data System (ADS)

    Klüser, Lars; Di Biagio, Claudia; Kleiber, Paul D.; Formenti, Paola; Grassian, Vicki H.

    2016-07-01

    Optical properties (extinction efficiency, single scattering albedo, asymmetry parameter and scattering phase function) of five different desert dust minerals have been calculated with an asymptotic approximation approach (AAA) for non-spherical particles. The AAA method combines Rayleigh-limit approximations with an asymptotic geometric optics solution in a simple and straightforward formulation. The simulated extinction spectra have been compared with classical Lorenz-Mie calculations as well as with laboratory measurements of dust extinction. This comparison has been done for single minerals and with bulk dust samples collected from desert environments. It is shown that the non-spherical asymptotic approximation improves the spectral extinction pattern, including position of the extinction peaks, compared to the Lorenz-Mie calculations for spherical particles. Squared correlation coefficients from the asymptotic approach range from 0.84 to 0.96 for the mineral components whereas the corresponding numbers for Lorenz-Mie simulations range from 0.54 to 0.85. Moreover the blue shift typically found in Lorenz-Mie results is not present in the AAA simulations. The comparison of spectra simulated with the AAA for different shape assumptions suggests that the differences mainly stem from the assumption of the particle shape and not from the formulation of the method itself. It has been shown that the choice of particle shape strongly impacts the quality of the simulations. Additionally, the comparison of simulated extinction spectra with bulk dust measurements indicates that within airborne dust the composition may be inhomogeneous over the range of dust particle sizes, making the calculation of reliable radiative properties of desert dust even more complex.

  8. The Use of Oil Refinery Wastes as a Dust Suppression Surfactant for Use in Mining

    SciTech Connect

    Dixon-Hardy, D.W.; Beyhan, S.; Ediz, I.G.; Erarslan, K.

    2008-10-15

    In this research, the suitability of a selection of petroleum refinery wastes as a dust suppressant were examined. Dust is a significant problem in surface and underground mining mainly because of its adverse effects on human health and machinery. Hence, dust control and suppression is a vital part of mine planning for mining engineers. Water is the oldest and the cheapest suppressant in dealing with the mine dusts. However, surfactant use has recently been used for a wider range of applications in the mining industry. In order to carry out laboratory experiments, a dust chamber was designed and manufactured. The chamber has an inlet for coal dust entrance and a nozzle for spraying water and the oil refinery wastes. Water and the surfactants were mixed at various ratios and then sprayed onto the coal dusts within the cell. Dust concentration was measured systematically to determine the effects of surfactant containing solution on the coal dust and the data obtained by the measurements were analyzed. The results showed that the oil refinery wastes could be used as a dust suppressant, which may create an economical utilization for the wastes concerned.

  9. Chemical and Physical Characteristics of Sediments from Prevalent Dust Sources in the Central Chihuahuan Desert, Chihuahua, Mexico

    NASA Astrophysics Data System (ADS)

    Dominguez Acosta, M.; Gill, T. E.; Peinado, P.

    2013-05-01

    The Chihuahuan Desert has been recognized as an important contributor of mineral aerosols emplaced into the atmosphere in the Western Hemisphere. Along with the production of these aerosols, growing concern has been stated relating the downwind transport of atmospheric dust particles to increases in human health related impacts such as asthma and bronchitis in the Binational Paso Del Norte, the largest urban area in the region. Efforts have been made to describe the source types (land use/cover) and frequency of emission from the "dust hotspots" or prevalent sources within the region. These studies have outlined specific areas and their related sedimentological environments responsible for the regular dust production. Ephemeral lakes, fluvial and alluvial related environments form the main natural dust producing landforms in the region, modulated by short-term climatic variability and anthropogenic disturbance. Analysis of remote sensing imagery shows that the margins between natural areas and agricultural lands form the main anthropogenic related source areas. Most of the previously published studies focus on these remotely sensed descriptions of the dust sources, while only a few deal with in situ or field characteristics of these sources. A formal and detailed description of the physicochemical properties of many of these areas is presented, providing key data on this component of the overall dust production cycle. Elemental and mineralogical compositions of dust source sediments, soil textural compositions (grain size distributions) and field sedimentological descriptions are presented as an effort to attain a detailed in situ description of the prevalent dust sources in the central part of the Chihuahuan Desert.

  10. A Combined Observational and Modeling Approach to Study Modern Dust Transport from the Patagonia Desert to East Antarctica

    NASA Technical Reports Server (NTRS)

    Gasso, S.; Stein, A.; Marino, F.; Castellano, E.; Udisti, R.; Ceratto, J.

    2010-01-01

    The understanding of present atmospheric transport processes from Southern Hemisphere (SH) landmasses to Antarctica can improve the interpretation of stratigraphic data in Antarctic ice cores. In addition, long range transport can deliver key nutrients normally not available to marine ecosystems in the Southern Ocean and may trigger or enhance primary productivity. However, there is a dearth of observational based studies of dust transport in the SH. This work aims to improve current understanding of dust transport in the SH by showing a characterization of two dust events originating in the Patagonia desert (south end of South America). The approach is based on a combined and complementary use of satellite retrievals (detectors MISR, MODIS, GLAS ,POLDER, OMI,), transport model simulation (HYSPLIT) and surface observations near the sources and aerosol measurements in Antarctica (Neumayer and Concordia sites). Satellite imagery and visibility observations confirm dust emission in a stretch of dry lakes along the coast of the Tierra del Fuego (TdF) island (approx.54deg S) and from the shores of the Colihue Huapi lake in Central Patagonia (approx.46deg S) in February 2005. Model simulations initialized by these observations reproduce the timing of an observed increase in dust concentration at the Concordia Station and some of the observed increases in atmospheric aerosol absorption (here used as a dust proxy) in the Neumayer station. The TdF sources were the largest contributors of dust at both sites. The transit times from TdF to the Neumayer and Concordia sites are 6-7 and 9-10 days respectively. Lidar observations and model outputs coincide in placing most of the dust cloud in the boundary layer and suggest significant de- position over the ocean immediately downwind. Boundary layer dust was detected as far as 1800 km from the source and approx.800 km north of the South Georgia Island over the central sub-Antarctic Atlantic Ocean. Although the analysis suggests the

  11. A combined observational and modeling approach to study modern dust transport from the Patagonia desert to East Antarctica

    NASA Astrophysics Data System (ADS)

    Gassó, S.; Stein, A.; Marino, F.; Castellano, E.; Udisti, R.; Ceratto, J.

    2010-09-01

    The understanding of present atmospheric transport processes from Southern Hemisphere (SH) landmasses to Antarctica can improve the interpretation of stratigraphic data in Antarctic ice cores. In addition, long range transport can deliver key nutrients normally not available to marine ecosystems in the Southern Ocean and may trigger or enhance primary productivity. However, there is a dearth of observational based studies of dust transport in the SH. This work aims to improve current understanding of dust transport in the SH by showing a characterization of two dust events originating in the Patagonia desert (south end of South America). The approach is based on a combined and complementary use of satellite retrievals (detectors MISR, MODIS, GLAS, POLDER, OMI), transport model simulation (HYSPLIT) and surface observations near the sources and aerosol measurements in Antarctica (Neumayer and Concordia sites). Satellite imagery and visibility observations confirm dust emission in a stretch of dry lakes along the coast of the Tierra del Fuego (TdF) island (~54° S) and from the shores of the Colihue Huapi lake in Central Patagonia (~46° S) in February 2005. Model simulations initialized by these observations reproduce the timing of an observed increase in dust concentration at the Concordia Station and some of the observed increases in atmospheric aerosol absorption (here used as a dust proxy) in the Neumayer station. The TdF sources were the largest contributors of dust at both sites. The transit times from TdF to the Neumayer and Concordia sites are 6-7 and 9-10 days respectively. Lidar observations and model outputs coincide in placing most of the dust cloud in the boundary layer and suggest significant deposition over the ocean immediately downwind. Boundary layer dust was detected as far as 1800 km from the source and ~800 km north of the South Georgia Island over the central sub-Antarctic Atlantic Ocean. Although the analysis suggests the presence of dust at

  12. From dust to varnish: Geochemical constraints on rock varnish formation in the Negev Desert, Israel

    NASA Astrophysics Data System (ADS)

    Goldsmith, Yonaton; Stein, Mordechai; Enzel, Yehouda

    2014-02-01

    Chemical compositions of rock varnish from the Negev Desert of Israel and local settled dust were used to constrain the mechanisms of varnish formation and patterns of Mn enrichment and accumulation in the varnish. Rock varnish was sampled from coeval, undisturbed prehistoric flint artifacts along a south-north climatic transect (˜30-120 mm/yr of rain). Our analyses indicate that Mn, Ba and Pb in the varnish are significantly enriched (˜100×) in respect to the local settling dust and that Mn content systematically fluctuates with depth in the varnish. The varnish and settled dust data combined with basic thermodynamic and kinetic reasoning are used to constrain the following geochemical model of rock varnish formation: dust accumulates in micro-basins on exposed rock surfaces, under pH ˜8 (common Negev value) and during wetting by dew and rain, Mn in the dust is mobilized and leached to a depth of ˜5 μm under the varnish surface where Hollandite Mn-oxides precipitate and are adsorbed onto and between the porous clay minerals that comprise most of the varnish. During its mobile phase Mn-oxide is negatively charged and adsorbs rare earth elements. Once the solution dries abrasion removes the upper, weakly cemented dust sediment, which contains mainly Si, Al and Fe (which are not mobile at pH ˜8). Ca is also removed in large quantities. Mn, Ba, Pb and the REE are deposited at a depth and thus, protected from erosion. Reoccurrences of these processes result in a noticeable accumulation of these elements, but not of Si, Al or Fe. The alternating Mn-rich and Mn-poor laminas form as a result of a competition between the leaching rate of Mn and the adhesion rate of the clay minerals. When moisture is high (low), lamina with high (low) Mn/clay mineral ratio forms. The oxidation states involved in the varnish formation are unknown, therefore, to use Morgan's calculations we must assume, in agreement with the thermodynamic considerations (presented above), that during

  13. From dust to varnish: Geochemical constraints on rock varnish formation in the Negev Desert, Israel

    NASA Astrophysics Data System (ADS)

    Goldsmith, Yonaton; Stein, Mordechai; Enzel, Yehouda

    2014-02-01

    Chemical compositions of rock varnish from the Negev Desert of Israel and local settled dust were used to constrain the mechanisms of varnish formation and patterns of Mn enrichment and accumulation in the varnish. Rock varnish was sampled from coeval, undisturbed prehistoric flint artifacts along a south-north climatic transect (˜30-120 mm/yr of rain). Our analyses indicate that Mn, Ba and Pb in the varnish are significantly enriched (˜100×) in respect to the local settling dust and that Mn content systematically fluctuates with depth in the varnish. The varnish and settled dust data combined with basic thermodynamic and kinetic reasoning are used to constrain the following geochemical model of rock varnish formation: dust accumulates in micro-basins on exposed rock surfaces, under pH ˜8 (common Negev value) and during wetting by dew and rain, Mn in the dust is mobilized and leached to a depth of ˜5 μm under the varnish surface where Hollandite Mn-oxides precipitate and are adsorbed onto and between the porous clay minerals that comprise most of the varnish. During its mobile phase Mn-oxide is negatively charged and adsorbs rare earth elements. Once the solution dries abrasion removes the upper, weakly cemented dust sediment, which contains mainly Si, Al and Fe (which are not mobile at pH ˜8). Ca is also removed in large quantities. Mn, Ba, Pb and the REE are deposited at a depth and thus, protected from erosion. Reoccurrences of these processes result in a noticeable accumulation of these elements, but not of Si, Al or Fe. The alternating Mn-rich and Mn-poor laminas form as a result of a competition between the leaching rate of Mn and the adhesion rate of the clay minerals. When moisture is high (low), lamina with high (low) Mn/clay mineral ratio forms. The oxidation states involved in the varnish formation are unknown, therefore, to use Morgan's calculations we must assume, in agreement with the thermodynamic considerations (presented above), that during

  14. Desert dust and anthropogenic aerosol interactions in the Community Climate System Model coupled-carbon-climate model

    SciTech Connect

    Mahowald, Natalie; Rothenberg, D.; Lindsay, Keith; Doney, Scott C.; Moore, Jefferson Keith; Randerson, James T.; Thornton, Peter E; Jones, C. D.

    2011-02-01

    Coupled-carbon-climate simulations are an essential tool for predicting the impact of human activity onto the climate and biogeochemistry. Here we incorporate prognostic desert dust and anthropogenic aerosols into the CCSM3.1 coupled carbon-climate model and explore the resulting interactions with climate and biogeochemical dynamics through a series of transient anthropogenic simulations (20th and 21st centuries) and sensitivity studies. The inclusion of prognostic aerosols into this model has a small net global cooling effect on climate but does not significantly impact the globally averaged carbon cycle; we argue that this is likely to be because the CCSM3.1 model has a small climate feedback onto the carbon cycle. We propose a mechanism for including desert dust and anthropogenic aerosols into a simple carbon-climate feedback analysis to explain the results of our and previous studies. Inclusion of aerosols has statistically significant impacts on regional climate and biogeochemistry, in particular through the effects on the ocean nitrogen cycle and primary productivity of altered iron inputs from desert dust deposition.

  15. Elemental and ionic composition of atmospheric aerosols in the dust storm season in Mongolian Gobi Desert

    NASA Astrophysics Data System (ADS)

    Soyol-Erdene, T. O.; Shagjjamba, D.; Hong, S.; Sarangerel, E.; Byambatsogt, K.

    2014-12-01

    TSP (Total Suspended Particulate) PM10 (particle size smaller than 10 μm) and PM2.5 (particle size smaller than 2.5 μm) aerosol samples in the dust storm session in Mongolian Gobi Desert were collected and their water soluble ionic and elemental composition were elaborated in demonstrating the mixing of mineral aerosol with pollution aerosol. During the sampling period (5-15 April, 2014) the dust storm peaked on 14 April, in which the highest concentrations of PM10 and PM2.5 were 250.1 and 33.4 respectively. The water soluble anions (SO42-, NO3-, Cl- and HCO3- and PO43-) and cations (Na+, K+, NH4+, Ca2+, Mg2+ and Li+) of the samples were determined by ion chromatograph. Elemental composition for 48 elements determined by using X-ray fluorescence analyzer. For the PM2.5 samples, concentrations of V, Ge, As, Se, Br, Ag, Hg, Tl, Bi were less than instrumental detection limit and Cr, Co, Cu, Nb, Mo, Sb, I, Ba, Ce, Hf, W, Au, Pb were determined only in a few samples. Other elements were observed in most samples. For the PM2.5-10 samples, concentrations of Ge, As, Se, Br, Ag, Hf, Tl were less than instrumental detection limit and V, Co, Nb, Mo, I, Ce, W, Pb were determined only small samples. Others are determined in most samples. Aerosol sources, sources fractions (mineral and pollution), and mixing of aerosols from various sources will be investigated by further data analyses.

  16. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: DUST SUPPRESSANT PRODUCTS: SYNTECH PRODUCTS CORPORATION'S TECHSUPPRESS

    EPA Science Inventory

    Dust suppressant products used to control particulate emissions from unpaved roads are among the technologies evaluated by the Air Pollution Control Technology (APCT) Verification Center, part of the U.S. Environmental Protection Agency's Environmental Technology Verification (ET...

  17. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: DUST SUPPRESSANT PRODUCTS: MIDWEST INDUSTRIAL SUPPLY, INC.'S EK35

    EPA Science Inventory

    Dust suppressant products used to control particulate emissions from unpaved roads are among the technologies evaluated by the Air Pollution Control Technology (APCT) Verification Center, part of the U.S. Environmental Protection Agency's Environmental Technology Verification (ET...

  18. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: DUST SUPPRESSANT PRODUCTS: SYNTECH PRODUCTS CORPORATION'S PETROTAC

    EPA Science Inventory

    Dust suppressant products used to control particulate emissions from unpaved roads are among the technologies evaluated by the Air Pollution Control Technology (APCT) Verification Center, part of the U.S. Environmental Protection Agency's Environmental Technology Verification (ET...

  19. EVALUATION OF THE EFFECTIVENESS OF CHEMICAL DUST SUPPRESSANTS ON UNPAVED ROADS

    EPA Science Inventory

    The report gives results of measurements of the long-term effectiveness of five unpaved-road chemical dust suppressants. Effectiveness at controlling total particulate emissions in three size fractions was determined over several cycles of chemical application, control effectiven...

  20. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: DUST SUPPRESSANT PRODUCTS: MIDWEST INDUSTRIAL SUPPLY, INC.'S ENVIROKLEEN

    EPA Science Inventory

    Dust suppressant products used to control particulate emissions from unpaved roads are among the technologies evaluated by the Air Pollution Control Technology (APCT) Verification Center, part of the U.S. Environmental Protection Agency's Environmental Technology Verification (ET...

  1. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: DUST SUPPRESSANT PRODUCTS: NORTH AMERICAN SALT COMPANY'S DUSTGARD

    EPA Science Inventory

    Dust suppressant products used to control particulate emissions from unpaved roads are among the technologies evaluated by the Air Pollution Control Technology (APCT) Verification Center, part of the U.S. Environmental Protection Agency's Environmental Technology Verification (ET...

  2. In situ and Remote Sensing Characterization of California Wildfires and Nevada Desert Dust

    NASA Astrophysics Data System (ADS)

    Air, Dambar S.

    Atmospheric aerosols exert significant influence on the climate and cause problems in human health and ecosystem. This dissertation reports aerosol physical and optical properties obtained from ground based remote sensing instruments, the Multifilter Rotating Shadowband Radiometer (MFRSR) and Cimel sun photometer, and in-situ measurements from photoacoustic (PA) instruments. The measurements were performed during California Rim fire of 2013, desert storm of 2013, and clear sky days. A 2-stream radiation transfer model and Mie theory were used to calculate the retrieved values of solar irradiances and aerosol optical properties. The ground based measurements were also compared with the satellite (Terra MODIS, Aqua MODIS and Deep Blue) measurements. The aerosol optical properties retrieved with the MFRSR show excellent agreement with those obtained with a co-located Cimel sun photometer. However, the comparison with the satellite measurements indicates significant departure from the ground based measurements. The values of the aerosol optical depth (AOD) and Angstrom exponent (AE) during the Rim fire event remained higher than clear sky days due to the presence of smoke particles in the atmosphere. However, the values of AOD during the dust storm were higher but the AE become lower than the clear sky days due to the presence of large particles in the atmosphere. The concentration of the fine mode (diameter less than 1 micron) dominates over the coarse mode (diameter greater than 1 micron) particles during the Rim fire, while coarse particles were more prevalent during dust storm. Back trajectory analysis during the Rim fire indicated that the southerly wind brought the plumes of smoke which originated at California Rim fire toward Reno. Similarly, the back trajectory analysis during the dust storm suggested that the dust was generated from the Humboldt sink and traveled towards Reno. The single scattering albedo (SSA) was found to decrease with wavelength due to the

  3. Optical characteristics of biomass burning and desert dust over the Western Mediterranean during summer: a case study

    NASA Astrophysics Data System (ADS)

    Basart, Sara; Sicart, Michaël; María Baldasano, José; Lane, Diego; Comerón, Adolfo

    2013-04-01

    The present contribution reports on the aerosol vertical distributions in Barcelona (Spain) which were obtained when very high aerosol concentrations were observed on summer 2012. An EARLINET lidar system and AERONET sunphotometer located in Barcelona performed intensive measurements in the framework of the ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure Network) project. The data that were collected allow the characterization of the optical properties of the aerosols in this region, benefiting from the synergy of various remote sensing instruments. Due to its location in the Mediterranean basin, Barcelona metropolitan area is influenced by two major aerosol source regions: Europe and the Western Mediterranean Basin, as a major source of anthropogenic pollutants, and North Africa, as a principal source of natural dust. As a result, the composition of atmospheric aerosols in Barcelona station is a mixing of aerosols. During the period between 1 - 2 July, AOD reached high values (~ 0.5). In addition to anthropogenic local contributions, other aerosols long-range transported were also detected. Between 1 - 3 July, strong forest fires occurred in Alicante where advected to Barcelona area. On the other hand, between 28th June and 1st July, the northeastern Iberian Peninsula was affected by the intrusion of Saharan dust. The presence of Saharan dust was successfully forecasted by the BSC-DREAM8b dust regional model. MODIS and AERONET data, as well as air-mass backward trajectories confirmed the existence of biomass burning and desert dust in the case examined. Desert dust was detected between 2 and 4 km (above sea level, a.s.l) with maximum dust concentrations at ~ 4 km a.s.l on 1st June. On the other hand, favourable meteorological conditions made possible that biomass burning from Alicante was southern advected to Barcelona during the study period.

  4. Mineral Dust Analysis and Application in Refining Source Region Information for the Sahara and East Asia Deserts

    NASA Astrophysics Data System (ADS)

    Reid, E. A.; Reid, J. S.; Westphal, D.; Cliff, S.; Dunlap, M.

    2002-12-01

    The study of transported mineral dust aerosols relies heavily on simplified dust source region parameters. Source regions are broadly defined by soil class and expected erodibility, factors which continuously changes with land use and climate conditions. Mineral dust particles may undergo numerous cycles of deposition and re-entrainment prior to collection and analysis. Using the Sahara Desert and the East Asia deserts as test cases, we investigate the possibility of retrieving source information from receptor sites through single particle and bulk analyses of collected aerosol particles. In June and July of 2000, Saharan mineral dust aerosols transported across the Atlantic Ocean to Puerto Rico were collected for bulk and single particle chemical and morphological analyses. The Puerto Rico Dust Experiment, (PRIDE), involved sampling aerosols upwind of the islands at various altitudes in the marine boundary layer (MBL) and Saharan Air Layer (SAL) via a Navajo research aircraft. A surface site included a Davis Rotating Drum (DRUM) cascade impactor to size segregate the aerosols into eight stages, from 12 to 0.1 micrometers, with four-hour time resolution. In April of 2001, size segregated Asian mineral dust aerosols were collected by three hour resolution DRUM samplers at surface sites in Cheju, Taiwan, for bulk chemical analysis. The aircraft samples and selected DRUM samples were subjected to single particle analysis by scanning electron microscopy (SEM) for particle morphology, and by Energy Dispersive Analysis with X-rays (EDAX) to derive elemental ratios of key soil elements. The DRUM samples were subjected to X-Ray Fluorescence (XRF) to derive bulk elemental composition for elements Al though Zn. Cluster and principal component analysis of the data derived statistically significant particle groupings. By including particle morphology data, and using ternary analyses, derivation of additional source information was possible. Particle compositions

  5. Detection of dust and sandstorms from Taklamakan Desert to Japan by using MODIS mosaic images

    NASA Astrophysics Data System (ADS)

    Kato, Yoshinobu

    2008-12-01

    In recent years, the number of days which dust and sandstorms (DSS) events were observed is increasing in Japan, Korea, China and Mongolia. The Aerosol Vapor Index (AVI) method is a DSS detection method. The AVI is defined as AVI=Tb32-Tb31 for MODIS data of Terra and Aqua satellites, where Tb31 is the brightness temperature of band 31 (10.780-11.280μm) and Tb32 is that of band 32 (11.770-12.270μm). The MODIS mosaic images of true-color, AVI and thermal images are made for the detection of DSS from Taklamakan Desert to Japan. The detection of DSS is possible both at daytime and night, because the AVI method is used. The density of DSS is classified into six levels from 0 (DSS none) to 5 (DSS strong) according to the AVI values. The DSS phenomena during 6-11 April 2006 are analyzed by using the mosaic images of Terra-MODIS. The number of pixels, which is approximately equal to the area of square kilometers, at each level of DSS density is measured. The AVI value at sea is about 0.2-2.3K lower than that at land, because of the influence of water vapor. In daytime, the generation place of DSS hidden under the cloud can be estimated by comparing AVI image with true-color and thermal images.

  6. Soil desiccation rate integration into empirical dust emission models for polymer suppressant evaluation.

    PubMed

    Bae, Sunyoung; Inyang, Hilary I; De Brito Galvão, T C; Mbamalu, Godwin E

    2006-04-30

    Dust constitutes an environmental and human health menace in many regions of the world. The rate of soil desiccation is a significant determinant of the availability of fine soil particles for entrainment in air as dust. Dust suppressants such as polymer solutions can reduce soil desiccation rate, thereby reducing dust emission factor. Herein, a dust emission estimation methodology that involves the integration of desiccation time curves to find the average desiccation rate is formulated. This is combined with soil characteristics, stressor (environmental and possibly vehicle) characteristics and liquid content in soil to estimate potential emission factors. Using this methodology, the dust suppression potential of aqueous polyethylene oxide (PEO) solution was investigated experimentally with Na-montmorillonite (Na-mmt) as the model dust-generating material. PEO with a molecular weight of 8 x 10(6) and at aqueous concentrations ranging from 0.5 to 10 g/L, was mixed with 10 g of Na-mmt (surface area=31.82+/-0.22 m2/g) and desiccated for 700 h in a specially designed chamber at 25 degrees C and 30% relative humidity. The results show that generally, aqueous PEO is superior to distilled water as a dust suppressant for Na-mmt at concentrations in the range of 0.5-2.0 g/L. The experimental data obtained are introduced into the formulated estimation methodology, and potential emissions of dust from PEO-admixed Na-mmt are determined. PMID:16442727

  7. Desert dust,Ocean spray,Volcanoes,Biomass burning: Pathways of nutrients into Andean rainforests

    NASA Astrophysics Data System (ADS)

    Fabian, P.; Rollenbeck, R.; Spichtinger, N.; Dominguez, G.; Brothers, L.; Thiemens, M.

    2009-04-01

    Regular rain and fogwater sampling in the Podocarpus National Park, along an altitude profile between 1800 and 3185 m, has been carried out since 2002.The research area located in southern Ecuador on the wet eastern slopes of the Andes is dominated by trade winds from easterly directions. The samples, generally accumulated over 1-week intervals, have been analysed for pH,conductivity and major ions(K+,Na+,NH4+,Ca2+,Mg 2+,SO42-,NO3-,PO43). For all components a strong seasonal variation is observed,while the altitudinal gradient is less pronounced. About 35 % of the weekly samples had very low ion contents,at or below the detection limit, with pH generally above 5 and conductivity below 10 uS/cm.10 days back trajectories (FLEXTRA) showed that respective air masses originated in pristine continental areas,with little or no obvious pollution sources. About 65 %,however,were significantly loaded with cations and anions,with pH often as low as 3.5 to 4.0 and conductivity up to 50 uS/cm.Back trajectories showed that respective air masses had passed over areas of intense biomass burning,volcanoes,and the ocean,with even episodic Sahara and/or Namib desert dust interference. Enhanced SO4 2-and NO3- were identified,by combining satellite-based fire pixels with back trajectories,as predominantly resulting from biomass burning. Analyses of oxygen isotopes 16O ,17O ,and 18O of nitrate show that nitrate in fog samples is a product of atmospheric conversion of precursors.For most cases,by using emission inventories, anthropogenic precursor sources other than forest fires could be ruled out,thus leaving biomass burning as the main source of nitrate and sulphate in rain and fogwater. Some SO4 2- ,about 10 % of the total input,could be identified to originate from active volcanoes, whose plumes were sometimes encountered by the respective back trajectories. Enhanced Na +, K + ,and Cl - was found to originate from ocean spray sources.They were associated with strong winds providing

  8. ESR signal intensity and crystallinity of quartz from Gobi and sandy deserts in East Asia and implication for tracing Asian dust provenance

    NASA Astrophysics Data System (ADS)

    Sun, Youbin; Chen, Hongyun; Tada, Ryuji; Weiss, Dominik; Lin, Min; Toyoda, Shin; Yan, Yan; Isozaki, Yuko

    2013-08-01

    Electron spin resonance (ESR) signal intensity and crystallinity index (CI) of fine- (<16 µm) and coarse-grained (>16 µm) quartz were measured in surface samples from the Taklimakan desert in western China, the Badain Juran, Tengger and Mu Us deserts in northern China, and the Gobi desert in southern Mongolia to evaluate whether these geophysical parameters can serve as reliable provenance tracers of Asian dust. The results indicate that spatial variability of both ESR signal intensity and CI is evident within the Taklimakan deserts and the Mongolian Gobi, but less significant in the three deserts of northern China. Coarse-grained quartz from the Mongolian Gobi and northern China deserts can be differentiated from the Taklimakan desert using the ESR signal intensity. Fine-grained quartz originating from three major Asian dust sources, i.e., the Gobi-sandy deserts in western China, northern China and southern Mongolia, can be distinguished effectively using the combination of ESR and CI signals. Our results suggest that ESR signal intensity and CI can discriminate the sources of fine-grained quartz better than coarse-grained quartz, providing an effective approach to trace the provenance of fine-grained dust deposition on the land and in the ocean.

  9. Use of Satellite and Ground-based Digital Images to Detect and Monitor Dust Storms in the Mojave Desert

    NASA Astrophysics Data System (ADS)

    Chavez, P. S.; MacKinnon, D. J.; Reynolds, R. L.; Velasco, M. G.

    2002-12-01

    Wind-induced dust emission from sources in the southwestern United States is not a major contributor to global dust flux, but it is important on a regional and national scale because of its effects on air quality, human health and safety, as well as ecosystem dynamics. Integrated remotely sensed satellite, airborne, and ground-based image data have strong potential to detect and monitor active dust storms and map areas vulnerable to wind erosion in the Southwest. Since 1999, high temporal resolution digital images collected by satellite and a ground-based, automated digital camera station have been used to detect, monitor, and analyze the location, size, frequency, duration, and transport patterns of large dust storms in the central Mojave Desert. One of the biggest dust storms of this past decade occurred on April 15, 2002, when at least several million metric tons of dust were emitted from the central Mojave Desert alone. During this storm, geostationary satellite (GOES) images documented the arrival of two very large dust plumes into the Las Vegas Valley, NV, one from a valley about 40 km to the west and the other from a heavily used area about 170 km to the southwest. Large, rapid increases in levels of PM10 (particulate matter less than 10 micrometers) in the Las Vegas area corresponded with the arrival of these plumes, with PM10 values increasing from a range of approximately 100 to 250 micrograms/m3 to 1,100 to 1,500 micrograms/m3 within 30 minutes. Satellite imaging systems currently available cannot detect and monitor dust storms of the size typically generated in the Southwest on an operational basis or be used to produce models for emission-rate predictions. The satellite imaging system on GOES is the only one available having adequate temporal resolution to detect and monitor active dust storms on a routine basis; however, it can only detect very large dust storms because its spatial and spectral resolutions are very low. A satellite imaging system with

  10. Middle East Health and Air Quality Utilizing NASA EOS in the Saharan and Arabian Deserts to Examine Dust Particle Size and Mineralogy of Aerosols

    NASA Technical Reports Server (NTRS)

    Keeton, Tiffany; Barrick, Bradley; Cooksey, Kirstin; Cowart, Kevin; Florence, Victoria; Herdy, Claire; Padgett-Vasquez, Steve; Luvall, Jeffrey; Molthan, Andrew

    2012-01-01

    Ground-based studies conducted in Iraq have revealed the presence of potential human pathogens in airborne dust. According to the Environmental Protection Agency (EPA), airborne particulate matter below 2.5micron (PM2.5) can cause long-term damage to the human respiratory system. NASA fs Earth Observing System (EOS) can be used to determine spectral characteristics of dust particles and dust particle sizes. Comparing dust particle size from the Sahara and Arabian Deserts gives insight into the composition and atmospheric transport characteristics of dust from each desert. With the use of NASA SeaWiFS DeepBlue Aerosol, dust particle sizes were estimated using Angstrom Exponent. Brightness Temperature Difference (BTD) equation was used to determine the area of the dust storm. The Moderate-resolution Imaging Spectroradiometer (MODIS) on Terra satellite was utilized in calculating BTD. Mineral composition of a dust storm that occurred 17 April 2008 near Baghdad was determined using imaging spectrometer data from the JPL Spectral Library and EO-1 Hyperion data. Mineralogy of this dust storm was subsequently compared to that of a dust storm that occurred over the Bodele Depression in the Sahara Desert on 7 June 2003.

  11. Implications of high altitude desert dust transport from Western Sahara to Nile Delta during biomass burning season.

    PubMed

    Prasad, Anup K; El-Askary, Hesham; Kafatos, Menas

    2010-11-01

    The air over major cities and rural regions of the Nile Delta is highly polluted during autumn which is the biomass burning season, locally known as black cloud. Previous studies have attributed the increased pollution levels during the black cloud season to the biomass or open burning of agricultural waste, vehicular, industrial emissions, and secondary aerosols. However, new multi-sensor observations (column and vertical profiles) from satellites, dust transport models and associated meteorology present a different picture of the autumn pollution. Here we show, for the first time, the evidence of long range transport of dust at high altitude (2.5-6 km) from Western Sahara and its deposition over the Nile Delta region unlike current Models. The desert dust is found to be a major contributor to the local air quality which was previously considered to be due to pollution from biomass burning enhanced by the dominant northerly winds coming from Europe. PMID:20797813

  12. Differences in Fine- Coarse Aerosol Ratios in Convective and Non-Convective Dust Events in a Desert City

    NASA Astrophysics Data System (ADS)

    Gill, T. E.; Rivera Rivera, N. I.; Novlan, D. J.

    2014-12-01

    El Paso, Texas (USA) and Ciudad Juarez, Chihuahua (Mexico) form the Paso del Norte, the largest metropolitan area in North America's Chihuahuan Desert. The cities are subject to frequent dust storms presenting a hazard to local infrastructure and health, including synoptic-scale dust events during winter and spring, and dusty outflows from convective storms (haboobs) primarily during the summer. We evaluate particulate matter (PM2.5 and PM10) concentrations over a decade of convective and non-convective dust events, based on hourly aerosol data collected by Texas Commission on Environmental Quality (TCEQ) continuous air monitors in El Paso cross-referenced to weather observations from the USA National Weather Service. A total of 219 dust events (95 convective and 124 non-convective) events occurred between 2001 and 2010. The PM2.5/PM10 ratio was significantly higher (proportionally greater concentration of fine aerosols) in convective episodes and during summertime events than during non-convective dust events and dust episodes in other seasons, although overall concentrations of both PM2.5 and PM10 were higher in the non-convective events, which were also longer-lasting. These differences in fine/coarse aerosol ratios are likely related to different atmospheric stability conditions, and/or different mechanisms of dust particle entrainment and transport in haboobs versus non-convective dust events. Since visibility degradation and adverse human health effects are known to be exacerbated by to fine aerosol concentrations, thunderstorm-related dust events may present a proportionally greater hazard.

  13. DEFINITION OF THE LONG-TERM CONTROL EFFICIENCY OF CHEMICAL DUST SUPPRESSANTS APPLIED TO UNPAVED ROADS

    EPA Science Inventory

    The paper presents the methodology and results of a field testing program to quantify the long-term efficiency of chemical dust suppressants applied to industrial unpaved roads. Three generic categories of suppressants were evaluated: water, a water-based petroleum resin, and a w...

  14. Desert Dust Outbreaks in Southern Europe: Contribution to Daily PM10 Concentrations and Short-Term Associations with Mortality and Hospital Admissions

    PubMed Central

    Stafoggia, Massimo; Zauli-Sajani, Stefano; Pey, Jorge; Samoli, Evangelia; Alessandrini, Ester; Basagaña, Xavier; Cernigliaro, Achille; Chiusolo, Monica; Demaria, Moreno; Díaz, Julio; Faustini, Annunziata; Katsouyanni, Klea; Kelessis, Apostolos G.; Linares, Cristina; Marchesi, Stefano; Medina, Sylvia; Pandolfi, Paolo; Pérez, Noemí; Querol, Xavier; Randi, Giorgia; Ranzi, Andrea; Tobias, Aurelio; Forastiere, Francesco

    2015-01-01

    Background: Evidence on the association between short-term exposure to desert dust and health outcomes is controversial. Objectives: We aimed to estimate the short-term effects of particulate matter ≤ 10 μm (PM10) on mortality and hospital admissions in 13 Southern European cities, distinguishing between PM10 originating from the desert and from other sources. Methods: We identified desert dust advection days in multiple Mediterranean areas for 2001–2010 by combining modeling tools, back-trajectories, and satellite data. For each advection day, we estimated PM10 concentrations originating from desert, and computed PM10 from other sources by difference. We fitted city-specific Poisson regression models to estimate the association between PM from different sources (desert and non-desert) and daily mortality and emergency hospitalizations. Finally, we pooled city-specific results in a random-effects meta-analysis. Results: On average, 15% of days were affected by desert dust at ground level (desert PM10 > 0 μg/m3). Most episodes occurred in spring–summer, with increasing gradient of both frequency and intensity north–south and west–east of the Mediterranean basin. We found significant associations of both PM10 concentrations with mortality. Increases of 10 μg/m3 in non-desert and desert PM10 (lag 0–1 days) were associated with increases in natural mortality of 0.55% (95% CI: 0.24, 0.87%) and 0.65% (95% CI: 0.24, 1.06%), respectively. Similar associations were estimated for cardio-respiratory mortality and hospital admissions. Conclusions: PM10 originating from the desert was positively associated with mortality and hospitalizations in Southern Europe. Policy measures should aim at reducing population exposure to anthropogenic airborne particles even in areas with large contribution from desert dust advections. Citation: Stafoggia M, Zauli-Sajani S, Pey J, Samoli E, Alessandrini E, Basagaña X, Cernigliaro A, Chiusolo M, Demaria M, Díaz J, Faustini A

  15. Geochemical Fluxes Associated With a Long-range Dust Cloud From the Gobi Desert Region, Central Asia.

    NASA Astrophysics Data System (ADS)

    Zdanowicz, C. M.; Hall, G. E.; Vaive, J. E.

    2003-12-01

    In early April, 2001, an exceptionally intense series of dust storms originated in the Gobi desert region of southern Mongolia and northern China. The dust cloud generated during these storms was tracked by satellite over the North Pacific Ocean and was detected all across North America. Instrumented floats deployed in the subarctic western Pacific Ocean revealed a near-doubling of the carbon biomass in the mixed layer over the 2-week period following the passage of the dust cloud, illustrating the impact of the dust on biological productivity in the surface Ocean (Bishop et al. 2002, Nature vol. 298). During its passage over northwestern America ca April 13, 2001, the Gobi dust plume deposited a widespread, distinctive layer of yellowish-red dust-laden snow, up to 5-cm thick, in the icefields of the St-Elias mountains, Yukon Territory. The dust fallout was probably enhanced by snowfall scavenging associated with orographic uplift of the moist Pacific air mass over the high mountain range (max elevation 5959 m). Samples of dust-laden snow were collected from a series of sites on the Mount Logan massif (60 N, 140 W), during a glaciological research expedition. The samples, collected between elevations of 2400 and 5340 m, contained as much as 80 ppm (mass) of dust. The dust particles were analyzed in the laboratories of the Geological Survey of Canada to characterize their physical attributes (e.g., grain size distribution) as well as their bulk mineralogical and geochemical composition. The concentrations of over 60 major, minor and trace elements were determined using ICP-MS an ICP-ES, including some important nutrients and biolimiting to biointermediate elements such as P, Si, Ba and Ca. Using these measurements, we calculated first-order estimates of the depositional fluxes for various geochemical elements associated with the Gobi dust fallout. Such detailed compositional data on far-traveled dust clouds are rarely available. We hope our findings presented here

  16. Sensitivity of desert dust emission modelling to horizontal resolution: the example of the Bodélé Depression

    NASA Astrophysics Data System (ADS)

    Bouet, Christel; Cautenet, Guy; Marticorena, Béatrice; Bergametti, Gilles; Minvielle, Fanny; Schmechtig, Catherine; Laurent, Benoit

    2010-05-01

    Atmospheric aerosols are known to play an important role in the Earth's climate system. However, the quantification of aerosol radiative impact on the Earth's radiative budget is very complex because of the high variability in space and time of aerosol mass and particle number concentrations, and optical properties as well. In many regions, like in desert regions, dust is the largest contribution to aerosol optical thickness [Tegen et al., 1997]. Consequently, it appears fundamental to well represent mineral dust emissions to reduce uncertainties concerning aerosol radiative impact on the Earth's radiative budget. Recently, several studies (e.g. Prospero et al. [2002]) underlined that the Bodélé depression, in northern Chad, is probably the most important source of mineral dust in the world. However many models fail in simulating these large dust emissions. Indeed, dust emission is a threshold phenomenon mainly driven by the intensity of surface wind velocity. Realistic estimates of dust emissions then rely on the quality and accuracy of the surface wind fields. Koren and Kaufman [2004] showed that the reanalysis data (NCEP), which can be used as input data in numerical models, underestimates surface wind velocity in the Bodélé Depression by up to 50%. Such an uncertainty on surface wind velocity cannot allow an accurate simulation of the dust emission. In mesoscale meteorological models, global reanalysis datasets are used to initialize and laterally nudge the models that compute meteorological parameters (like wind velocity) with a finer spatial and temporal resolutions. The question arises concerning the precision of the wind speeds calculated by these models. Using the Regional Atmospheric Modeling System (RAMS, Cotton et al. [2003]) coupled online with the dust production model developed by Marticorena and Bergametti [1995] and recently improved by Laurent et al. [2008] for Africa, the influence of the horizontal resolution of the mesoscale meteorological

  17. Saharan Desert Dust Radiative Impact On The Evolution of The Vertical Thermal Characteristics of The Atmosphere Over The Mediterranean

    NASA Astrophysics Data System (ADS)

    Iori, C.; Liberti, G. L.

    The passage of Saharan dust over the Mediterranean basin, represents the most in- tense and relatively frequent event for what concerns the tropospheric aerosols in that region. Transport of the crustal dusts from the Saharan surface to the mean Mediter- ranean troposphere happens inside air volumes belonging to the superficial layers of the Sahara desert. As a consequence, it is associated with anomalies both in the verti- cal thermodynamic structure as well as in the composition. The first one is due to the avvection of air volumes geographically and vertically belonging to a different region. The second one is due to the composition of the air volumes (water vapour, ozone and aerosol) different from the one of the unperturbed status. Due to the occurence of such anomalies a perturbation in the radiative balance is also expected, because of the in- teraction of water vapour, ozone and aerosol with the atmospheric radiation field and hence with the radiative balance of earth-atmosphere system. This study examine the relative contribution of radiative processes in the evolution of the vertical structure of the atmosphere during the occurence of a desert dust transport event (18-5-1999). In order to do that radiosoundings from a set of stations around the Mediterranean Sea as well as in the source area have been analysed for the spring 1999 to define a mean sta- tus and succesively characterize quantitatively the anomaly associated with the event. In parallel detailed description of vertical properties of the aerosols as well as of the other parameters of interest, available from the PAUR II campaign [Kourtidis et al., 2000], has been employed for computing with the CLIRAD RTM [Chou and Suarez 1999; Chou and Suarez 2001] the heating/cooling rate profiles. Computation have been performed for a day in presence of aerosol as well as for a relatively clear day in order to evaluate the desert dust contribution on the overall radiative effects. A detailed analysis of the

  18. Detection and Preliminary Assessment of Source Areas of the 15 December 2003 Dust Storm in the Chihuahuan Desert, Southwestern North America

    NASA Astrophysics Data System (ADS)

    Rivera Rivera, N. I.; Gill, T. E.; Bleiweiss, M. P.; Hand, J. L.; Dominguez A., M.; Ruiz, A.; Perez, A. E.; Emmert, S. P.; Lee, J. A.; Mulligan, K. R.

    2005-12-01

    Dust storms can disperse large quantities of fine aeolian sediment regionally and even globally. These extreme aerosol events frequently originate with multiple dust plumes developing simultaneously over a large region. Dust outbreaks originating in the southwestern USA and northern Mexico seasonally transport aerosols long distances across continental North America. However, dust sources in this region are not well characterized. Remote sensing data can be used to assess the frequency and magnitude of these dust events for potential impacts on climate, visibility and health-related air quality issues. We applied a technique that consists of examining visible spectral bands, as well as difference "split-window" images for far-infrared (far-IR) channels using a variety of satellite imagery (NOAA/GOES/GVAR/Imager, NOAA/POES/AVHRR and NASA/TERRA/MODIS). This technique was used to locate the origin of multiple dust plumes in the Chihuahuan Desert region of the southwestern United States and northwestern Mexico during a significant dust event that occurred on December 15, 2003. After dust sources were identified, we superimposed their locations on Landsat-7 images to assess surface features of these aeolian "hotspots," and visited many of these sites to determine the geomorphology, soil/sediment properties, and land use associated with these dust sources. Dust plumes in the Chihuahuan Desert on 15 December 2003 emanated from several land types, including saline playas, bare desert soils, disturbed/abandoned lands, and agricultural areas. In Mexico, sources included several sites along the edges of pluvial Lake Palomas near the contacts between sand sheets and lacustrine sediments, small dry lake beds (lagunas secas) and several sites in the Casas Grandes river basin in Chihuahua. In the United States, dust emission hotspots included dry, unvegetated saline playas (the White Sands near the E and SE edges of Lake Lucero, New Mexico, and the northern Salt Basin west of the

  19. EXTENDED EVALUATION OF UNPAVED ROAD DUST SUPPRESSANTS IN THE IRON AND STEEL INDUSTRY

    EPA Science Inventory

    The report gives results of a study to measure the long-term control effectiveness of various dust suppressants used to mitigate particulate emissions from vehicular traffic on unpaved roads in the iron and steel industry. Control effectiveness was determined by measuring emissio...

  20. Effect of the temperature variation between Mediterranean Sea and Syrian deserts on the dust storm occurrence in the western half of Iran

    NASA Astrophysics Data System (ADS)

    Amanollahi, Jamil; Kaboodvandpour, Shahram; Qhavami, Samira; Mohammadi, Bakhtiyar

    2015-03-01

    Recent dust storms have caused crises in western Iran, which necessitate the prediction of these storms a few days before their occurrence. This is the first study of its type that analyzes the effect of temperature differences between the Mediterranean Sea surface and Syrian deserts (creation zone of the dusts storms) on the formation of dust storms in the west of Iran. The study also seeks to identify any changes in the atmospheric temperature created by the extreme dust storm of July 5, 2009 in west of Iran (Sanandaj City). In this study, the MODIS images from 2000 to 2008, and particulate matter data of the Sanandaj station from 2008 to 2012 were utilized to identify the dust storm days. The Mediterranean Sea surface temperature data were extracted from NOAA satellites for dust storm days up to four days preceding them. The web site of world weather was used to obtain the temperature of Damascus, Syria station as the selected land station. According to the results, significant differences were acquired between surface temperatures of Damascus station and the Mediterranean Sea in the dust storm days and up to three days before them. As the dust storm days approached, a rising trend was observed in changes of the temperature difference between land and sea. Thermal map analysis of the atmosphere of the Syrian deserts on July 5, 2009 showed significant decrease in the levels of 1000 hPa and 500 hPa but for the days preceding it no significant changes were observed. It can be concluded that the temperature difference between the Mediterranean Sea surface and the Syrian deserts four days before the dust storm occurrences is the important factor in predicting this event.

  1. Control of Lunar and Martian dust--experimental insights from artificial and natural cyanobacterial and algal crusts in the desert of Inner Mongolia, China.

    PubMed

    Liu, Yongding; Cockell, Charles S; Wang, Gaohong; Hu, Chunxiang; Chen, Lanzhou; De Philippis, Roberto

    2008-02-01

    Studies on the colonization of environmentally extreme ground surfaces were conducted in a Mars-like desert area of Inner Mongolia, People's Republic of China, with microalgae and cyanobacteria. We collected and mass-cultured cyanobacterial strains from these regions and investigated their ability to form desert crusts artificially. These crusts had the capacity to resist sand wind erosion after just 15 days of growth. Similar to the surface of some Chinese deserts, the surface of Mars is characterized by a layer of fine dust, which will challenge future human exploration activities, particularly in confined spaces that will include greenhouses and habitats. We discuss the use of such crusts for the local control of desert sands in enclosed spaces on Mars. These experiments suggest innovative new directions in the applied use of microbe-mineral interactions to advance the human exploration and settlement of space. PMID:18240967

  2. Study of the Mediterranean desert dust outbreaks' vertical structure based on a synergistic use of satellite and ground retrievals

    NASA Astrophysics Data System (ADS)

    Gkikas, Antonis; Basart, Sara; Hatzianastassiou, Nikos; Pey, Jorge; Querol, Xavier; Amiridis, Vasilis; Jorba, Oriol; Gasso, Santiago; Baldasano, Jose Maria

    2015-04-01

    The Mediterranean basin is frequently affected by dust outbreaks originating from the north African and Middle East deserts. These outbreaks reveal strong spatial and temporal variability which is mainly determined by the prevailing synoptic conditions. Aiming to their description, a synergistic use of various measurements can be the optimal approach. The scope of the present study is to describe the 3D structure of Mediterranean dust outbreaks through a synergistic use of various satellite observations. For this purpose, daily retrievals of aerosol optical depth (AOD550nm), Ångström exponent (α), effective radius (reff), aerosol index (AI) and fine fraction (FF) were taken by the MODIS-Terra/Aqua (Collection 051), EP-TOMS and OMI-Aura databases. These data are used as inputs to an objective and dynamic algorithm which identifies and classifies desert dust (DD) episodes into strong and extreme ones, in each 1° x 1° grid cell, over the periods 2000-2013 and 2003-2012. However, the specific satellite retrievals refer to the whole atmospheric column and thus are not able to provide information at different heights. In order to address this issue, coincident CALIOP-CALIPSO observations have been aggregated and averaged for 16 layers up to 8km, equally spaced in vertical terms. During the period 2000-2013, strong and extreme DD episodes occurred more frequently over the western (9.9 episodes/year) and central parts (3.3 episodes/year) of the Mediterranean. Although the episodes taking place in the eastern Mediterranean are less frequent, they appear to be the most intense, with maximum intensities up to 1.3 and 3.0 (in terms of AOD) for strong and extreme ones, respectively. Based on the CALIPSO retrievals, dust aerosol layers extend from 0.5 to 4.5km above sea level (a.s.l.) near to the northern African coasts, gradually getting narrower up to the 40o N parallel. Dust particles can be uplifted even higher, up to 8km, between the parallels of 33o N and 37o N. In

  3. African desert dust in the Caribbean atmosphere: Microbiology and public health

    USGS Publications Warehouse

    Griffin, Dale W.; Garrison, V.H.; Herman, J.R.; Shinn, E.A.

    2001-01-01

    Air samples collected on St. John in the U.S. Virgin Islands were screened for the presence of viable bacteria and fungi to determine if the number of cultivatable microbes in the atmosphere differed between "clear atmospheric conditions" and "African dust-events." Results indicate that during "African dust-events," the numbers of cultivatable airborne microorganisms can be 2 to 3 times that found during "clear atmospheric conditions." Direct microbial counts of air samples using an epifluorescent microscopy assay demonstrated that during an "African dust-event," bacteria-like and virus-like particle counts were approximately one log greater than during "clear atmospheric conditions." Bacteria-like particles exhibiting autofluoresence, a trait of phototrophs, were only detected during an "African dust-event.".

  4. Altitude-resolved shortwave and longwave radiative effects of desert dust in the Mediterranean during the GAMARF campaign: Indications of a net daily cooling in the dust layer

    NASA Astrophysics Data System (ADS)

    Meloni, D.; Junkermann, W.; Sarra, A.; Cacciani, M.; De Silvestri, L.; Di Iorio, T.; Estellés, V.; Gómez-Amo, J. L.; Pace, G.; Sferlazzo, D. M.

    2015-04-01

    Desert dust interacts with shortwave (SW) and longwave (LW) radiation, influencing the Earth radiation budget and the atmospheric vertical structure. Uncertainties on the dust role are large in the LW spectral range, where few measurements are available and the dust optical properties are not well constrained. The first airborne measurements of LW irradiance vertical profiles over the Mediterranean were carried out during the Ground-based and Airborne Measurements of Aerosol Radiative Forcing (GAMARF) campaign, which took place in spring 2008 at the island of Lampedusa. The experiment was aimed at estimating the vertical profiles of the SW and LW aerosol direct radiative forcing (ADRF) and heating rates (AHR), taking advantage of vertically resolved measurements of irradiances, meteorological parameters, and aerosol microphysical and optical properties. Two cases, characterized respectively by the presence of a homogeneous dust layer (3 May, with aerosol optical depth, AOD, at 500 nm of 0.59) and by a low aerosol burden (5 May, with AOD of 0.14), are discussed. A radiative transfer model was initialized with the measured vertical profiles and with different aerosol properties, derived from measurements or from the literature. The simulation of the irradiance vertical profiles, in particular, provides the opportunity to constrain model-derived estimates of the AHR. The measured SW and LW irradiances were reproduced when the model was initialized with the measured aerosol size distributions and refractive indices. For the dust case, the instantaneous (solar zenith angle, SZA, of 55.1°) LW-to-SW ADRF ratio was 23% at the surface and 11% at the top of the atmosphere (TOA), with a more significant LW contribution on a daily basis (52% at the surface and 26% at TOA), indicating a relevant reduction of the SW radiative effects. The AHR profiles followed the aerosol extinction profile, with comparable peaks in the SW (0.72 ± 0.11 K d-1) and in the LW (-0.52 ± 0.12 K d-1

  5. Middle East Desert Dust Exposure: Health Risks from Metals and Microbial Pathogens

    NASA Astrophysics Data System (ADS)

    Lyles, M. B.

    2014-12-01

    In the Middle East, dust and sand storms are a persistent problem and can deliver significant amounts of micro-particulates via inhalation into the mouth, nasal pharynx, & lungs due to the fine size and abundance of these micro-particulates. The chronic and acute health risks of this dust inhalation have not been well studied nor has the dust been effectively characterized as to its chemical composition, mineral content, or microbial flora. Scientific experiments were designed to study the Kuwaiti and Iraqi dust as to its physical, chemical, and biological characteristics and for its potential to cause adverse health effects. First, dust samples from different locations were collected and processed and exposure data collected. Initial chemical and physical characterization of each sample including particle size distribution and inorganic analysis was conducted, followed by characterization of biologic flora of the dust, including bacteria, fungi and viruses. Data indicates that the mineralized dust is composed of calcium carbonate over a matrix of metallic silicate nanocrystals containing a variety of trace and heavy metals constituting ~3 % of the PM10 particles by weight, of which ~1% is bioaccessible aluminum and reactive iron, each. The particles also consist of ~1% bioavailable aluminum and reactive iron each. Microbial analysis reveals a significant biodiversity of bacterial, fungi, and viruses of which ~30% are known pathogens. Of the microbes identified, several have hemolytic properties and most have significant antibiotic resistance. Viral analysis indicates a tremendous amount of virons with a large percent of RNA viruses. The level of total suspended particle mass at PM 10 along with environmental & physiological conditions present constitute an excessive exposure to micro-particulates including PM 2.5 and the potential for adverse health effects. Reported data on cell culture and animal studies have indicated a high level of toxicity to these dust

  6. Suppression of gas detonation by a dust cloud at reduced mixture pressures

    NASA Astrophysics Data System (ADS)

    Pinaev, A. V.; Vasil'ev, A. A.; Pinaev, P. A.

    2015-05-01

    The decay of a detonation wave in a mixture propagating through a dust cloud is experimentally studied for three types of silica sand with particle sizes 250-600, 120-250, and 90-120 , mean volume densities 2.2-3.5 g/l, and initial pressure 0.1-0.01 MPa. A non-monotonic character of reduction of wave velocity in the dust cloud is observed, where a secondary detonation can arise behind the leading front of the wave in the course of its attenuation. This situation is induced by the dual role of sand particles in decelerating the flow and simultaneously generating hot spots that promote reaction excitation. As a result, the mechanism of ignition in the decaying detonation wave becomes different. Critical parameters of the dust cloud providing complete suppression of the detonation wave and the flame propagating behind the latter at a reduced initial pressure of the gas mixture are determined.

  7. Influence of Asian Desert Dust on Lower Respiratory Tract Symptoms in Patients with Asthma over 4 Years.

    PubMed

    Watanabe, Masanari; Kurai, Jun; Igishi, Tadashi; Yamasaki, Akira; Burioka, Naoto; Takeuchi, Hiromi; Sako, Takanori; Touge, Hirokazu; Nakamoto, Masaki; Hasegawa, Yasuyuki; Chikumi, Hiroki; Matsumoto, Shingo; Yamasaki, Chie; Minato, Sayaka; Ueda, Yutaka; Horasaki, Kazunori; Watanabe, Tetsushi; Shimizu, Eiji

    2012-06-01

    The Asian Dust Storm (ADS) aggravates symptoms and pulmonary dysfunction in adult asthma patients. Our objective was to investigate the association of air pollutants and metals in desert dust with worsening of asthma symptoms during the ADS. A telephone survey was performed to investigate the upper and lower respiratory tract symptoms, ocular symptoms and skin symptoms of asthma patients during the ADS in March between 2007 and 2010. Four surveys were conducted in 46 patients. Two patients noted worsening of lower respiratory tract symptoms in all four surveys, as well as 2 patients in three surveys, 7 patients in two surveys, and 9 patients in one survey. There was no worsening of lower respiratory tract symptoms in 26 patients. In each patient, the influence of the ADS on lower respiratory tract symptoms varied between surveys. In 2010, the level of suspended particulate matter was highest in all four years, but the smallest number of patients noted worsening of lower respiratory tract symptoms. Among pollutants, only the maximum concentration of nitrogen dioxide during the ADS was significantly associated with the worsening of lower respiratory tract symptoms. The influence of the ADS on lower respiratory tract symptoms of adult asthma patients is variable. PMID:24031138

  8. Airborne microorganisms in the African desert dust corridor over the mid-Atlantic ridge, Ocean Drilling Program, Leg 209

    USGS Publications Warehouse

    Griffin, Dale W.; Westphal, Douglas L.; Gray, Michael A.

    2006-01-01

    The objective of this study was to enhance our understanding of the fate and trans-Atlantic transport of dustborne microorganisms from Northern Africa to the Caribbean and Americas, and more specifically to determine if culturable populations could be detected at a mid-ocean site, closer to the source of dust relative to land-based Caribbean sites, during the early summer months of May and June. Between the dates of 22 May and 30 June 2003, daily air samples were collected and evaluated for the presence of culturable bacterial and fungal colony-forming units (CFU). Here we report a statistically significant correlation between daily atmospheric CFU counts at a mid-ocean research site (???15??N, 45??W) and daily desert dust concentrations as determined by the U.S. Navy's Naval Aerosol Analysis and Prediction System (NAAPS) Global Aerosol Model (Honrath et al. (2004). Journal of Geophysical Research, 109; Johnson et al. (2003). Global Biogeochemical Cycles, 17, 1063; Reid et al. (2004). Geophysical Research Letters, 31; Schollaert, Yoder, Westphal, & O'Reilly (2003). Journal of Geophysical Research, 108, 3191). ?? Springer Science+Business Media B.V. 2006.

  9. Investigations of Desert Dust and Smoke in the North Atlantic in Support of the TOMS Instrument

    NASA Technical Reports Server (NTRS)

    Toon, Owen B.

    2005-01-01

    During the initial period of the work we concentrated on Saharan dust storms and published a sequence of papers (Colarco et a1 2002,2003a,b, Toon, 2004). The U.S. Air Force liked the dust model so well that they appropriated it for operational dust storm forecasting (Barnum et al., 2004). The Air Force has used it for about 5 yrs in the Middle East where dust storms cause significant operational problems. The student working on this project, Peter Colarco, has graduated and is now a civil servant at Goddard where he continues to interact with the TOMS team. This work helped constrain the optical properties of dust at TOMS wavelengths, which is useful for climate simulations and for TOMS retrievals of dust properties such as optical depth. We also used TOMS data to constrain the sources of dust in Africa and the Middle East, to determine the actual paths taken by Saharan dust storms, to learn more about the mechanics of variations in the optical depths, and to learn more about the mechanisms controlling the altitudes of the dust. During the last two years we have been working on smoke from fires. Black carbon aerosols are one of the leading factors in radiative forcing. The US Climate Change Science Program calls this area out for specific study. It has been suggested by Jim Hansen, and Mark Jacobsen among others, that by controlling emissions of black carbon we might reduce greenhouse radiative forcing in a relatively painless manner. However, we need a greatly improved understanding of the amount of black carbon in the atmosphere, where it is located, where it comes from, how it is mixed with other particles, what its actual optical properties are, and how it evolves. In order to learn about these issues we are using a numerical model of smoke. We have applied this model to the SAFARI field program data, and used the TOMS satellite observations in that period (Sept. 2000). Our goal is to constrain source function estimates for black carbon, and smoke optical

  10. Spectral aerosol optical depth characterization of desert dust during SAMUM 2006

    NASA Astrophysics Data System (ADS)

    Toledano, C.; Wiegner, M.; Garhammer, M.; Seefeldner, M.; Gasteiger, J.; Müller, D.; Koepke, P.

    2009-02-01

    ABSTRACT The aerosol optical depth (AOD) in the range 340-1550nm was monitored at Ouarzazate (Morocco) during the Saharan Mineral Dust Experiment (SAMUM) experiment in May-June 2006. Two different sun photometers were used for this purpose. The mean AOD at 500nm was 0.28, with a maximum of 0.83, and the mean Ångström exponent (AE) was 0.35. The aerosol content over the site changed alternatively from very low turbidity, associated to Atlantic air masses, to moderate dust load, associated to air masses arriving in the site from Algeria, Tunisia and Libya. The dusty conditions were predominant in the measurement period (78% of data), with AOD (500nm) above 0.15 and AE below 0.4. The spectral features of the AOD under dusty conditions are discussed. Air mass back trajectory analysis is carried out to investigate the origin and height patterns of the dust loaded air masses. The advection of dust occurred mainly at atmospheric heights below 3000m, where east flow is the predominant. At the 5000m level, the air masses originate mainly over the Atlantic Ocean. Finally the Optical Properties of Aerosols and Clouds (OPAC) model is used to perform a set of simulations with different aerosol mixtures to illustrate the measured AOD and AE values under varying dust concentrations, and a brief comparison with other measurement sites is presented.

  11. Dustiness of chopped straw as affected by lignosulfonate as a dust suppressant.

    PubMed

    Breum, N O; Nielsen, B H; Lyngbye, M; Midtgård, U

    1999-01-01

    Many sources add to the concentration of bioaerosols in livestock buildings, and source control is the number one priority for keeping a low concentration. Straw is a common but dusty bedding material in livestock buildings and the present study is focused on the dustiness of chopped straw (barley) as affected by lignosulfonate (LS) as a dust suppressant. A LS-solution was aerosolized in a spray chamber fitted to an existing bedding chopper to allow the chopped straw to adsorb the LS-solution. The dustiness of straw treated with LS was compared to non-treated straw. As storage conditions may affect dustiness, the study included treated straw kept for 4 weeks in sealed plastic bags. Dustiness of the chopped straw was measured in terms of the potential of the straw to emit bioaerosols in a rotating drum. The LS-treated straw proved low in dustiness compared to the non-treated straw. The dustiness with respect to the mass of dust was reduced by at least a factor of 6, and for fungi and endotoxin the factors of reduction were 4 and 3, respectively. Dustiness of LS-treated straw kept in plastic bags was reduced by a factor of 2 for mass of dust and by a factor of 4 for endotoxin, but dustiness for fungi was increased by a factor of 3. It is concluded that lignosulfonate has potential as a dust suppressant for chopped straw. PMID:10607994

  12. Using the significant dust deposition event on the glaciers of Mt.~Elbrus, Caucasus Mountains, Russia on 5 May 2009 to develop a method for dating and "provenancing" of desert dust events recorded in snow pack

    NASA Astrophysics Data System (ADS)

    Shahgedanova, M.; Kutuzov, S.; White, K. H.; Nosenko, G.

    2013-02-01

    A significant desert dust deposition event occurred on Mt. Elbrus, Caucasus Mountains, Russia on 5 May 2009, where the deposited dust later appeared as a brown layer in the snow pack. An examination of dust transportation history and analysis of chemical and physical properties of the deposited dust were used to develop a new approach for high-resolution "provenancing" of dust deposition events recorded in snow pack using multiple independent techniques. A combination of SEVIRI red-green-blue composite imagery, MODIS atmospheric optical depth fields derived using the Deep Blue algorithm, air mass trajectories derived with HYSPLIT model and analysis of meteorological data enabled identification of dust source regions with high temporal (hours) and spatial (ca. 100 km) resolution. Dust, deposited on 5 May 2009, originated in the foothills of the Djebel Akhdar in eastern Libya where dust sources were activated by the intrusion of cold air from the Mediterranean Sea and Saharan low pressure system and transported to the Caucasus along the eastern Mediterranean coast, Syria and Turkey. Particles with an average diameter below 8 μm accounted for 90% of the measured particles in the sample with a mean of 3.58 μm, median 2.48 μm. The chemical signature of this long-travelled dust was significantly different from the locally-produced dust and close to that of soils collected in a palaeolake in the source region, in concentrations of hematite. Potential addition of dust from a secondary source in northern Mesopotamia introduced uncertainty in the "provenancing" of dust from this event. Nevertheless, the approach adopted here enables other dust horizons in the snowpack to be linked to specific dust transport events recorded in remote sensing and meteorological data archives.

  13. Using the significant dust deposition event on the glaciers of Mt. Elbrus, Caucasus Mountains, Russia on 5 May 2009 to develop a method for dating and provenancing of desert dust events recorded in snow pack

    NASA Astrophysics Data System (ADS)

    Shahgedanova, M.; Kutuzov, S.; White, K.; Nosenko, G.

    2012-09-01

    A significant desert dust deposition event occurred on Mt. Elbrus, Caucasus Mountains, Russia on 5 May 2009, where the deposited dust later appeared as a brown layer in the snow pack. An examination of dust transportation history and analysis of chemical and physical properties of the deposited dust were used to develop a new approach for high-resolution provenancing of dust deposition events recorded in snow pack using multiple independent techniques. A combination of SEVIRI red-green-blue composite imagery, MODIS atmospheric optical depth fields derived using the Deep Blue algorithm, air mass trajectories derived with HYSPLIT model and analysis of meteorological data enabled identification of dust source regions with high temporal (hours) and spatial (ca. 100 km) resolution. Dust, deposited on 5 May 2009, originated in the foothills of the Djebel Akhdar in eastern Libya where dust sources were activated by the intrusion of cold air from the Mediterranean Sea and Saharan low pressure system and transported to the Caucasus along the eastern Mediterranean coast, Syria and Turkey. Particles with an average diameter below 8 μm accounted for 90% of the measured particles in the sample with a mean of 3.58 μm, median 2.48 μm and the dominant mode of 0.60 μm. The chemical signature of this long-travelled dust was significantly different from the locally-produced dust and close to that of soils collected in a palaeolake in the source region, in concentrations of hematite and oxides of aluminium, manganese, and magnesium. Potential addition of dust from a secondary source in northern Mesopotamia introduced uncertainty in the provenancing of dust from this event. Nevertheless, the approach adopted here enables other dust horizons in the snowpack to be linked to specific dust transport events recorded in remote sensing and meteorological data archives.

  14. Desert dust in rural western US; the influence of dust storms, large particles, and land-use change on aerosol loads

    NASA Astrophysics Data System (ADS)

    Parks, D.; MacDonald, A. E.; Rosen, R. D.; Edmonds, H. N.; Key, E.; Swanberg, N.; Wiseman, W. J.; Sandgathe, S. A.; Neff, J. C.; Fernandez, D.; Munson, S.; Reynolds, R. L.

    2011-12-01

    Atmospheric aerosols are common in urban settings as well as dryland rural environments and are important to both climate and biogeochemical cycling. Most urban and far traveled aerosols are less than 10 micrometers in diameter with many particles in the less than 2.5 or 1 micrometer-size classes. Small aerosols, including many generated by industrial activity, are the focus of federal environmental law and have a major impact on human health. In rural areas of the western US, however, these small industrially derived particles appear to make up a small part of the overall aerosol load. Rather, dust in the rural West is dominated by mineral aerosols including a large amount of particles that range in size from 10 to 40 microns. These particles can travel for hundreds of kilometers, particularly during periods when dust storms are common. In the dusty spring and summer periods in and around Canyonlands and Mesa Verde National Parks, large particles (particles greater than 10 micrometers in diameter) appear to contribute between 50 and 90% to the overall particle load several meters above the ground. During large dust storms, concentrations of total suspended particulates increase by a factor of 8 to 10 while particles less than 10 micrometers in diameter are minimally affected. The presence of large particles in the atmosphere of the rural West is notable for several reasons. First, the majority of the existing aerosol monitoring networks focus on the small particle-size classes of less than 2.5 and 10 microns. Because many aerosol-collection instruments are designed with specific particle-size cutoff criteria, these instruments and the networks that depend on them are effectively blind to the larger particles that can dominate aerosol loads in the West. Second, for large portions of the year including the spring and summer months when dust storms are common, large particles likely play a major role in visibility restrictions across the protected airsheds of the

  15. A water soluble additive to suppress respirable dust from concrete-cutting chainsaws: a case study.

    PubMed

    Summers, Michael P; Parmigiani, John P

    2015-01-01

    Respirable dust is of particular concern in the construction industry because it contains crystalline silica. Respirable forms of silica are a severe health threat because they heighten the risk of numerous respirable diseases. Concrete cutting, a common work practice in the construction industry, is a major contributor to dust generation. No studies have been found that focus on the dust suppression of concrete-cutting chainsaws, presumably because, during normal operation water is supplied continuously and copiously to the dust generation points. However, there is a desire to better understand dust creation at low water flow rates. In this case study, a water-soluble surfactant additive was used in the chainsaw's water supply. Cutting was performed on a free-standing concrete wall in a covered outdoor lab with a hand-held, gas-powered, concrete-cutting chainsaw. Air was sampled at the operator's lapel, and around the concrete wall to simulate nearby personnel. Two additive concentrations were tested (2.0% and 0.2%), across a range of fluid flow rates (0.38-3.8 Lpm [0.1-1.0 gpm] at 0.38 Lpm [0.1 gpm] increments). Results indicate that when a lower concentration of additive is used exposure levels increase. However, all exposure levels, once adjusted for 3 hours of continuous cutting in an 8-hour work shift, are below the Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) of 5 mg/m(3). Estimates were made using trend lines to predict the fluid flow rates that would cause respirable dust exposure to exceed both the OSHA PEL and the American Conference of Governmental Industrial Hygienists (ACGIH®) threshold limit value (TLV). PMID:25714034

  16. Composition of aeolian dust in natural traps on isolated surfaces of the central Mojave Desert - Insights to mixing, sources, and nutrient inputs

    USGS Publications Warehouse

    Reynolds, R.L.; Reheis, M.; Yount, J.; Lamothe, P.

    2006-01-01

    The recognition and characterization of aeolian dust in soil contribute to a better understanding of landscape and ecosystem dynamics of drylands. Results of this study show that recently deposited dust, sampled in isolated, mostly high-ground settings, is chemically and mineralogically similar on varied geologic substrates over a large area (15 000 km2) in the Mojave Desert. The silt-plus-clay fraction (fines) on these isolated surfaces is closely alike in magnetic-mineral composition, in contrast to greatly dissimilar magnetic compositions of rock surfaces of vastly different lithologies, on which the fines have accumulated. The fines, thus, are predominantly deposited dust. The amounts of potential nutrients in the sampled dust are much more uniform than might be provided by direct, local weathering of bedrock or by dust locally derived from nearby weathered products. The compositional similarity of the dust on these surfaces is interpreted to result from mixing of fines in the atmosphere as well as in fluvial, alluvial, and lacustrine depositional settings prior to dust emission.

  17. Inhalable desert dust, urban emissions, and potentially biotoxic metals in urban Saharan-Sahelian air.

    PubMed

    Garrison, V H; Majewski, M S; Konde, L; Wolf, R E; Otto, R D; Tsuneoka, Y

    2014-12-01

    Saharan dust incursions and particulates emitted from human activities degrade air quality throughout West Africa, especially in the rapidly expanding urban centers in the region. Particulate matter (PM) that can be inhaled is strongly associated with increased incidence of and mortality from cardiovascular and respiratory diseases and cancer. Air samples collected in the capital of a Saharan-Sahelian country (Bamako, Mali) between September 2012 and July 2013 were found to contain inhalable PM concentrations that exceeded World Health Organization (WHO) and US Environmental Protection Agency (USEPA) PM2.5 and PM10 24-h limits 58 - 98% of days and European Union (EU) PM10 24-h limit 98% of days. Mean concentrations were 1.2-to-4.5 fold greater than existing limits. Inhalable PM was enriched in transition metals, known to produce reactive oxygen species and initiate the inflammatory response, and other potentially bioactive and biotoxic metals/metalloids. Eroded mineral dust composed the bulk of inhalable PM, whereas most enriched metals/metalloids were likely emitted from oil combustion, biomass burning, refuse incineration, vehicle traffic, and mining activities. Human exposure to inhalable PM and associated metals/metalloids over 24-h was estimated. The findings indicate that inhalable PM in the Sahara-Sahel region may present a threat to human health, especially in urban areas with greater inhalable PM and transition metal exposure. PMID:25243921

  18. Physical and Chemical Characteristics of Desert Dust Deposited on Mt. Elbrus, Caucasus as Documented in Snow Pit and Shallow Core Records

    NASA Astrophysics Data System (ADS)

    Kutuzov, S.; Shahgedanova, M.; Mikhalenko, V.; Ginot, P.; Lavrentiev, I.; Popov, G.

    2013-12-01

    We present a study of dust deposition events and its physical and chemical characteristics in Caucasus Mountains as documented by snow and firn pack at Mt Elbrus. Dust samples were collected from the shallow ice cores and snow pits in 2009-2013 at the western Elbrus plateau (5150 m a.s.l.). Particle size distribution and chemical analysis (major ions, trace elements) were completed for each sample using Coulter Counter Multisizer III, scanning electron microscopy (SEM), IC and ICPMS analysis. It was shown that desert dust deposition occurred in Caucasus 4-8 times a year and originates from the Northern Sahara and the deserts of the Middle East. Analysis of volumetric particle size distributions showed that the modal values ranged between 2 μm and 4 μm although most samples were characterised by modal values of 2.0-2.8 μm with an average of 2.6 μm. These values are lower than those obtained from the ice cores in central and southern Asia following the deposition of long-travelled dust and are closer to those reported for the European Alps and the polar ice cores. All samples containing dust have a single mode which is usually interpreted as a single source region. They do not reveal any significant differences between the Saharan and the Middle Eastern sources. The annual average dust mass concentrations were 10-15 mg kg-1 which is higher than the average concentrations reported for other mountain regions and this was strongly affected by dust deposition events. The deposition of dust resulted in elevated concentrations of most ions, especially Ca2+, Mg2+, K+, and sulphates. Dust originated from multiple sources in the Middle East including Mesopotamia or passing over the Middle East was characterised by the elevated concentrations of nitrates and ammonia which is related to a high atmospheric loads of ammonium emitted by agricultural sources and high concentrations of ammonium in dust originating from this region. By contrast, samples of the Saharan dust showed

  19. Birth cohort study on the effects of desert dust exposure on children's health: protocol of an adjunct study of the Japan Environment & Children’s Study

    PubMed Central

    Kanatani, Kumiko T; Adachi, Yuichi; Sugimoto, Nobuo; Noma, Hisashi; Onishi, Kazunari; Hamazaki, Kei; Takahashi, Yoshimitsu; Ito, Isao; Egawa, Miho; Sato, Keiko; Go, Tohshin; Kurozawa, Youichi; Inadera, Hidekuni; Konishi, Ikuo; Nakayama, Takeo

    2014-01-01

    Introduction Desert dust is estimated to constitute about 35% of aerosol in the troposphere. Desertification, climatic variability and global warming all can contribute to increased dust formation. This study aims to examine possible health effects of desert dust exposure on pregnant women and their children. The purpose of this report was to present the study protocol. Methods and analysis This 4-year birth cohort study began in 2011 as an adjunct study of the Japan Environment & Children’s Study (JECS) involving three regions: Kyoto, Toyama and Tottori. The JECS participants of the three regions above who also agreed to participate in this adjunct study were enrolled prior to delivery. Light Detecting and Ranging (LIDAR) with a polarisation analyser, which can distinguish mineral dust particles from other particles, is used for exposure measurements. Outcomes are allergic symptoms for mothers and development of asthma and other allergic or respiratory diseases for their children. Data are acquired in a timely manner by connecting local LIDAR equipment to an online questionnaire system. Participants answer the online questionnaire using mobile phones or personal computers. Ethics and dissemination The study protocol was approved by the ethics committees of Kyoto University, University of Toyama and Tottori University. All participants provided written informed consent. The results of this study will be published in peer-reviewed journals and disseminated to the scientific community and general public. Trial Registration number UMIN000010826. PMID:24958210

  20. Three-Dimensional Distribution of a Major Desert Dust Outbreak over East Asia in March 2008 Derived from IASI Satellite Observations

    NASA Technical Reports Server (NTRS)

    Cuesta, Juan; Eremenko, Maxim; Flamant, Cyrille; Dufour, Gaelle; Laurent, Benoît; Bergametti, Gilles; Hopfner, Michael; Orphal, Johannes; Zhou, Daniel

    2015-01-01

    We describe the daily evolution of the three-dimensional (3D) structure of a major dust outbreak initiated by an extratropical cyclone over East Asia in early March 2008, using new aerosol retrievals derived from satellite observations of IASI (Infrared Atmospheric Sounding Interferometer). A novel auto-adaptive Tikhonov-Phillips-type approach called AEROIASI is used to retrieve vertical profiles of dust extinction coefficient at 10 microns for most cloud-free IASI pixels, both over land and ocean. The dust vertical distribution derived from AEROIASI is shown to agree remarkably well with along-track transects of Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) spaceborne lidar vertical profiles (mean biases less than 110 meters, correlation of 0.95, and precision of 260 meters for mean altitudes of the dust layers). AEROIASI allows the daily characterization of the 3D transport pathways across East Asia of two dust plumes originating from the Gobi and North Chinese deserts. From AEROIASI retrievals, we provide evidence that (i) both dust plumes are transported over the Beijing region and the Yellow Sea as elevated layers above a shallow boundary layer, (ii) as they progress eastward, the dust layers are lifted up by the ascending motions near the core of the extratropical cyclone, and (iii) when being transported over the warm waters of the Japan Sea, turbulent mixing in the deep marine boundary layer leads to high dust concentrations down to the surface. AEROIASI observations and model simulations also show that the progression of the dust plumes across East Asia is tightly related to the advancing cold front of the extratropical cyclone.

  1. Three-dimensional distribution of a major desert dust outbreak over East Asia in March 2008 derived from IASI satellite observations

    NASA Astrophysics Data System (ADS)

    Cuesta, Juan; Eremenko, Maxim; Flamant, Cyrille; Dufour, Gaëlle; Laurent, Benoît; Bergametti, Gilles; Höpfner, Michael; Orphal, Johannes; Zhou, Daniel

    2015-07-01

    We describe the daily evolution of the three-dimensional (3D) structure of a major dust outbreak initiated by an extratropical cyclone over East Asia in early March 2008, using new aerosol retrievals derived from satellite observations of IASI (Infrared Atmospheric Sounding Interferometer). A novel auto-adaptive Tikhonov-Phillips-type approach called AEROIASI is used to retrieve vertical profiles of dust extinction coefficient at 10 µm for most cloud-free IASI pixels, both over land and ocean. The dust vertical distribution derived from AEROIASI is shown to agree remarkably well with along-track transects of CALIOP spaceborne lidar vertical profiles (mean biases less than 110 m, correlation of 0.95, and precision of 260 m for mean altitudes of the dust layers). AEROIASI allows the daily characterization of the 3D transport pathways across East Asia of two dust plumes originating from the Gobi and North Chinese deserts. From AEROIASI retrievals, we provide evidence that (i) both dust plumes are transported over the Beijing region and the Yellow Sea as elevated layers above a shallow boundary layer, (ii) as they progress eastward, the dust layers are lifted up by the ascending motions near the core of the extratropical cyclone, and (iii) when being transported over the warm waters of the Japan Sea, turbulent mixing in the deep marine boundary layer leads to high dust concentrations down to the surface. AEROIASI observations and model simulations also show that the progression of the dust plumes across East Asia is tightly related to the advancing cold front of the extratropical cyclone.

  2. Association of Kawasaki disease with tropospheric winds in Central Chile: is wind-borne desert dust a risk factor?

    PubMed

    Jorquera, Héctor; Borzutzky, Arturo; Hoyos-Bachiloglu, Rodrigo; García, Alvaro

    2015-05-01

    It has been found that Kawasaki disease (KD) cases diagnosed in Japan, Hawaii and San Diego, USA increase when tropospheric wind patterns arrive from central Asia, suggesting a common, wind-borne causal agent. We analyzed KD cases hospitalized in Santiago, Chile to look for associations with local, regional and large scale meteorological variables. We compiled monthly data of KD incidence rates, local meteorological variables, large scale wind patterns and several El Niño Southern Oscillation (ENSO) indices for 2001-2010; we considered standardized anomalies in all analyses and used linear time series models to account for data autocorrelation. We found that meteorological variables explain 38% of variance in KD rates. A unit increase in northerly wind at 3 lagged months, temperature at 1 and 3 lagged months and monthly change of ENSO 4 index are associated with changes in KD rates of 0.203 (95% CI 0.049-0.358), 0.181 (95% CI 0.014-0.347), 0.192 (95% CI 0.030-0.353) and -0.307 (95% CI -0.458-0.156), respectively. These results are robust when northerly wind level is changed or when a shorter period (2005-2010) is used to estimate model parameters. We found a statistical association of KD at Santiago, Chile with tropospheric, northerly wind patterns suggesting that dust transported from the Atacama Desert could include a causative agent. A novel result is that ENSO dynamics also explain part of KD variability with a decrease in KD when La Niña is dissipating or El Niño is on the rise; hence climate scale dynamics might be taken into account in future studies worldwide - at least as a potential explanatory variable that may confound KD seasonality on a global scale. PMID:25743034

  3. Provenance changes of eolian dust at Lingtai section in the Chinese Loess Plateau since 7 Ma and its implication for desert development in East Asia

    NASA Astrophysics Data System (ADS)

    Isozaki, Y.; Tada, R.; Sun, Y.; Nagashima, K.; Zheng, H.; Toyoda, S.; Tani, A.

    2008-03-01

    It is suggested that the uplift of Himalaya-Tibetan Plateau enhanced interior aridity in East Asia and resulted in development of middle latitude gobi and sandy deserts and accumulation of the eolian sediments in the Chinese Loess Plateau. Therefore, estimation of the provenance for eolian sediments in the Chinese Loess Plateau is critical to reconstruct the environmental changes in East Asia and their relation to the Himalaya-Tibetan Plateau uplift. We recently developed a new provenance tracing method by using a combination of Electron Spin Resonance (ESR) signal intensity and Crystallinity Index (CI) of quartz, and demonstrated that fine fraction of the surface sediments from nine major deserts in East Asia could be distinguished one another on the ESR signal intensity versus CI diagram. Here, we measured ESR signal intensity and CI of quartz in fine fractions of samples covering the last 7 Ma obtained from Lingtai section in the central Chinese Loess Plateau, and compared the results with those of the surface samples from nine major deserts in East Asia. The results suggest that the provenance of fine fraction of the eolian sediment in Lingtai section changed at 4.3, 2.1, 1.4, 1.1, 0.8 and 0.4 Ma. During 7 to 4.3 Ma, the dust might be have been supplied from Precambrian to Paleozoic metamorphic and granitic rocks and granite exposed in the present central to eastern part of the Tian Shan Mountains. The contribution from the Taklimakan desert appeared at 4.3 Ma, increased drastically at 1.1 Ma, and persisted till 0.8 Ma, whereas the main source of detrital material to the Taklimakan desert might have changed from eastern part of the Kunlun and the Altyn Mountains to western part of the Kunlun and the Tian Shan Mountains. During 0.8 to 0.4 Ma, contribution from the Badain Juran desert gradually increased. Finally, contribution from the Tengger desert appeared from 0.4 to 0 Ma. Together with tectonic evidences from literatures, the provenance changes from 4.3 to 0

  4. Observation of low single scattering albedo of aerosols in the downwind of the East Asian desert and urban areas during the inflow of dust aerosols

    NASA Astrophysics Data System (ADS)

    Khatri, Pradeep; Takamura, Tamio; Shimizu, Atsushi; Sugimoto, Nobuo

    2014-01-01

    We analyzed data observed at Fukue-jima (32.752°N, 128.682°E), the downwind of the East Asian desert and urban areas, during the spring season (March-April) of 2008-2011 aiming to understand the light-absorption capacity of Asian dust aerosols, which is a topic of controversy. We observed the decreasing tendency of single-scattering albedo (SSA) with the decrease of Ångström exponent and the increase of the ratio of dust aerosol optical thickness to total aerosol optical thickness, suggesting the important role of coarse-mode dust aerosols on observed low SSAs. The observational data further indicated that the low SSAs during strong dust events were less likely due to the effect of only strong light-absorbing carbonaceous aerosols, such as black carbon (BC), indicating the association of aerosol size distribution on modulating SSA. Such observational results are justified by numerical calculations showing that aerosol size distribution can be the key factor on modulating SSA even without any change in relative amount of light-absorbing aerosol as well as total aerosol optical thickness. Therefore, the observed low SSAs in the downwind regions during dust events could be partially due to the dominance of coarse-mode aerosols over fine-mode aerosols, which are usual in dust events, along with the effect of mixed light-absorbing aerosols. The study further suggests that such effect of aerosol size distribution on SSA can be one of the important reasons for the low SSAs of dust aerosols in the source region as reported by some studies, if coarse-mode aerosols dominate fine-mode aerosols.

  5. Desert Storm environmental effects

    NASA Astrophysics Data System (ADS)

    Kimball, E. W.

    It is noted that after more than six months of operation of the Patriot launch station in the Saudi Arabian desert no problems that were attributed to high temperature occurred. The environmental anomalies that did occur were cosmetic in nature and related to dust and salt fog. It was concluded that the Desert Storm environmental effects were typical of worldwide hot, dry climates.

  6. Geomorphologic approach for modelling the surface features of arid environments in a model of dust emissions: application to the Sahara desert

    NASA Astrophysics Data System (ADS)

    Callot, Yann; Marticorena, Béatrice; Bergametti, Gilles

    Mineral dust emissions from arid regions are influenced by the surface features encountered in the source regions. These surface features control both the erosion threshold and the intensity of the dust flux. Recently, a soil-derived dust emission scheme has been designed in order to provide an explicit representation of the mineral dust accounting for the influence of the surface features on the dust emissions. This physical scheme has been validated with micro-scale field measurements. Its large scale application has required the development of additional relations to estimate the input parameters from more accessible data: the mean height and the covering rate of the roughness elements and the mineralogical soil type. The determination of these surface data has been based on a geomorphologic approach which describes the surface features of arid areas in a 1 × 1° grid. Inside each square degree, up to five different areas characterised by different surface features have been distinguished. However, these areas have not been located inside the square degree. Each area can be constituted by several combined surface features, including roughness, vegetation, granulometry. Five main types of landscapes and eight main types of surface features have been distinguished. This approach is based on the combination of various data, mainly topographical, geological maps and climatological analysis. In addition to the problem of scale transfer, the main constraints to obtain a quantitative assessment are the confidence level of the existing data and the number of parameters to document. On the opposite, with this method, the fine scale required by the dust modelling can be separated from the scale accessible by the mapping approach, of the order of the square degree. This method can also be easily improved by aggregating new data and can be extended to other deserts. An example of application is given for the north-west of the Algerian Sahara where the method has been

  7. High-resolution provenance of desert dust deposited on Mt. Elbrus, Caucasus in 2009-2012 using snow pit and firn core records

    NASA Astrophysics Data System (ADS)

    Kutuzov, S.; Shahgedanova, M.; Mikhalenko, V.; Ginot, P.; Lavrentiev, I.; Kemp, S.

    2013-09-01

    The first record of dust deposition events on Mt. Elbrus, Caucasus Mountains derived from a snow pit and a shallow firn core is presented for the 2009-2012 period. A combination of isotopic analysis, SEVIRI red-green-blue composite imagery, MODIS atmospheric optical depth fields derived using the Deep Blue algorithm, air mass trajectories derived using the HYSPLIT model and analyses of meteorological data enabled identification of dust source regions with high temporal (hours) and spatial (ca. 20-100 km) resolution. Seventeen dust deposition events were detected; fourteen occurred in March-June, one in February and two in October. Four events originated in the Sahara, predominantly in northeastern Libya and eastern Algeria. Thirteen events originated in the Middle East, in the Syrian Desert and northern Mesopotamia, from a mixture of natural and anthropogenic sources. Dust transportation from Sahara was associated with vigorous Saharan depressions, strong surface winds in the source region and mid-tropospheric southwesterly flow with daily winds speeds of 20-30 m s-1 at 700 hPa level. Although these events were less frequent than those originating in the Middle East, they resulted in higher dust concentrations in snow. Dust transportation from the Middle East was associated with weaker depressions forming over the source region, high pressure centred over or extending towards the Caspian Sea and a weaker southerly or southeasterly flow towards the Caucasus Mountains with daily wind speeds of 12-18 m s-1 at 700 hPa level. Higher concentrations of nitrates and ammonium characterised dust from the Middle East deposited on Mt. Elbrus in 2009 indicating contribution of anthropogenic sources. The modal values of particle size distributions ranged between 1.98 μm and 4.16 μm. Most samples were characterised by modal values of 2.0-2.8 μm with an average of 2.6 μm and there was no significant difference between dust from the Sahara and the Middle East.

  8. Desert Dust Aerosol Air Mass Mapping in the Western Sahara, Using Particle Properties Derived from Space-Based Multi-Angle Imaging

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph; Petzold, Andreas; Wendisch, Manfred; Bierwirth, Eike; Dinter, Tilman; Esselborn, Michael; Fiebig, Marcus; Heese, Birgit; Knippertz, Peter; Mueller, Detlef; Schladitz, Alexander; Von Hoyningen-Huene, Wolfgang

    2008-01-01

    Coincident observations made over the Moroccan desert during the Sahara mineral dust experiment (SAMUM) 2006 field campaign are used both to validate aerosol amount and type retrieved from multi-angle imaging spectroradiometer (MISR) observations, and to place the suborbital aerosol measurements into the satellite s larger regional context. On three moderately dusty days during which coincident observations were made, MISR mid-visible aerosol optical thickness (AOT) agrees with field measurements point-by-point to within 0.05 0.1. This is about as well as can be expected given spatial sampling differences; the space-based observations capture AOT trends and variability over an extended region. The field data also validate MISR s ability to distinguish and to map aerosol air masses, from the combination of retrieved constraints on particle size, shape and single-scattering albedo. For the three study days, the satellite observations (1) highlight regional gradients in the mix of dust and background spherical particles, (2) identify a dust plume most likely part of a density flow and (3) show an aerosol air mass containing a higher proportion of small, spherical particles than the surroundings, that appears to be aerosol pollution transported from several thousand kilometres away.

  9. Desert Dust Air Mass Mapping in the Western Sahara, using Particle Properties Derived from Space-based Multi-angle Imaging

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph; Petzold, Andreas; Wendisch, Manfred; Bierwirth, Eike; Dinter, Tilman; Fiebig, Marcus; Schladitz, Alexander; von Hoyningen-Huene, Wolfgang

    2008-01-01

    Coincident observations made over the Moroccan desert during the SAhara Mineral dUst experiMent (SAMUM) 2006 field campaign are used both to validate aerosol amount and type retrieved from Multi-angle Imaging SpectroRadiometer (MISR) observations, and to place the sub-orbital aerosol measurements into the satellite's larger regional context. On three moderately dusty days for which coincident observations were made, MISR mid-visible aerosol optical thickness (AOT) agrees with field measurements point-by-point to within 0.05 to 0.1. This is about as well as can be expected given spatial sampling differences; the space-based observations capture AOT trends and variability over an extended region. The field data also validate MISR's ability to distinguish and to map aerosol air masses, from the combination of retrieved constraints on particle size, shape, and single-scattering albedo. For the three study days, the satellite observations (a) highlight regional gradients in the mix of dust and background spherical particles, (b) identify a dust plume most likely part of a density flow, and (c) show an air mass containing a higher proportion of small, spherical particles than the surroundings, that appears to be aerosol pollution transported from several thousand kilometers away.

  10. Size-Differentiated Chemical Composition of Re-Suspended Soil Dust from the Desert Southwest United States

    EPA Science Inventory

    As part of the Desert Southwest Coarse Particulate Matter Study which characterized the composition of fine and coarse particulate matter in Pinal County, AZ, several source samples were collected from several different soil types to assist in source apportionment analysis of the...

  11. Investigation on The Interlink Between Optical Properties of Dusts Over Taiwan and Thar Desert, India Using CALIPSO Data

    NASA Astrophysics Data System (ADS)

    Roja Raman, M.; Chen, Wei-Nai; He, Sin-Jie; Chen, Li-Ting; Hsu, Kai-Hsuan

    2016-06-01

    The optical properties (Angstrom exponent and depolarization) of aerosols are analyzed to characterize the dust particles at different altitudes of the atmosphere using the backscatter signal from the space borne Lidar (CALIPSO) over Asian region with emphasis on Taiwan and Indian regions. The physical and optical properties of dust particles are found different at wet and dry weather conditions. The size distribution of dust particles at different altitudes is estimated. Finally the correlation between the particle depolarization and the angstrom exponent of dust particles at different altitudes is analyzed and the possible reasons are discussed. Further, the spatial inhomogeneity in the correlation coefficient is noticed and the possible relation with regional weather conditions is discussed.

  12. Historical trends and sources of TSP in a Sonoran desert city: Can the North America Monsoon enhance dust emissions?

    NASA Astrophysics Data System (ADS)

    Moreno-Rodríguez, Verónica; Del Rio-Salas, Rafael; Adams, David K.; Ochoa-Landin, Lucas; Zepeda, Joel; Gómez-Alvarez, Agustín; Palafox-Reyes, Juan; Meza-Figueroa, Diana

    2015-06-01

    In this work, the trends of total suspended particulate matter (TSP) were analyzed during a period of 12 years (2000-2012) on the basis of meteorological parameters. The results of historical trends of TSP show that post-monsoon dust emission seems to be connected to rainfall distribution in the urban environment. Particulate matter is dominated by plagioclase, quartz, calcite, and montmorillonite phases with barium sulfate, and particles enriched in Cu, Fe, and Ce. Elemental composition and principal component analysis allow the identification of two major sources for metals incorporated in geogenic dust: cement, and traffic. Geochemical analysis of non-mobile trace elements show a similar signature as local cement brands in TSP filters, but it remains unknown if such a signature is related to cement production, erosion of buildings, or construction activities. La-Ce geochemical tracers show that geogenic dust is an important media of transportation for traffic, and cement-related contaminants. This work highlights the importance of monsoon season precipitation in dust generation in arid urban environments, and it could contribute to regional studies including the southwestern US regarding the dust emission processes and transport of pollutants across the trans-boundary.

  13. Navy Exploitation of SeaWiFS and MODIS Satellite Imagery for Detection of Desert Dust Storms Over Land and Water

    NASA Astrophysics Data System (ADS)

    Miller, S. D.

    2002-12-01

    The United States Navy gives serious consideration to the subject of dust detection. In a recent study of Naval aviation mishaps over the period 1990-1998 (Cantu, 2001), it was found that 70% were associated with visibility problems and accounted for annual equipment losses of nearly 50 million dollars. This figure does not include the tax dollars lost in jettisoned or off-target ordnance owing to obscured targets or failure of laser-guided systems in the presence of significant dust. Nor can it account for the loss of life during a subset of these mishaps. As such, a strong research emphasis has been placed on detecting and quantifying dust over data-sparse/denied parts of the world. The prolific and complex dust climatology of Southwest Asia has posed considerable challenges to Navy operations over the course of Operation Enduring Freedom. In an effort to support the ongoing needs of the Meteorology/Oceanography (METOC) officers afloat, the Satellite Applications Section of the Naval Research Laboratory (NRL) Marine Meteorology Division has developed a novel approach to enhancing significant dust events that appeals to high spatial and spectral resolution satellite data currently available from state of the art ocean/atmospheric radiometers. This paper summarizes progress made on daytime enhancements of desert dust storms over both land and ocean using multispectral imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS; aboard Earth Observing System Terra and Aqua platforms) and the Sea-viewing Wide Field-of-view Sensor (SeaWiFS; aboard the NASA/Orbimage SeaStar platform). The approach leverages the multi-spectral visible capability of these sensors to distinguish dust from clouds over water bodies, and the high spatial resolution required to refine the fine-scale structures that often accompany these events. The MODIS algorithm combines this information with that of several near-to-far infrared channels, taking advantage of unique spectral

  14. Novel Americium Treatment Process for Surface Water and Dust Suppression Water

    SciTech Connect

    Tiepel, E.W.; Pigeon, P.; Nesta, S.; Anderson, J.

    2006-07-01

    -241 contaminated pond water, surface run-off and D and D dust suppression water during the later stages of the D and D effort at Rocky Flats. This novel chemical treatment system allowed for highly efficient, high-volume treatment of all contaminated waste waters to the very low stream standard of 0.15 pCi/1 with strict compliance to the RFCA discharge criteria for release to off-site surface waters. The rapid development and implementation of the treatment system avoided water management issues that would have had to be addressed if contaminated water had remained in Pond A-4 into the Spring of 2005. Implementation of this treatment system for the Pond A-4 waters and the D and D waters from Buildings 776 and 371 enabled the site to achieve cost-effective treatment that minimized secondary waste generation, avoiding the need for expensive off-site water disposal. Water treatment was conducted for a cost of less than $0.20/gal which included all development costs, capital costs and operational costs. This innovative and rapid response effort saved the RFETS cleanup program well in excess of $30 million for the potential cost of off-site transportation and treatment of radioactive liquid waste. (authors)

  15. Stable isotope ratio measurements of Cu and Zn in mineral dust (bulk and size fractions) from the Taklimakan Desert and the Sahel and in aerosols from the eastern tropical North Atlantic Ocean.

    PubMed

    Dong, Shuofei; Weiss, Dominik J; Strekopytov, Stanislav; Kreissig, Katharina; Sun, Youbin; Baker, Alex R; Formenti, Paola

    2013-09-30

    Accurate characterization of the stable isotope composition of Cu and Zn in major global mineral dust sources and in aerosols is central to the application of these isotope systems to the studies of global geochemical processes and cycles. We test here for the first time Cu and Zn isotope ratios within a well-defined source-receptor setting on the continent-ocean interface and determine the isotope composition of (i) bulk surface soil dust samples from the Sahel region, (ii) individual size fractions of surface dust samples from the Taklimakan Desert, and (iii) aerosols collected in the equatorial eastern North Atlantic region. This is achieved reducing the blank contribution during the ion exchange step using small resin and acid volumes and using a second ion exchange passage to purify the Cu fraction. We find no significant correlation between size fractions and isotope ratios in the two samples analyzed from the Taklimakan Desert. Mass balance calculations suggest that isotope ratios of bulk samples are within the analytical precision of the <4 μm size fraction and can be used to characterize atmospheric long range transport of Cu and Zn in mineral dust from the Taklimakan Desert. The <1 µm size fractions of two aerosol samples collected over the equatorial eastern North Atlantic region have Cu and Zn isotope ratios that are different to Sahel surface soil dust suggesting important non-crustal sources, in line with calculated enrichment factors, and possibly of anthropogenic origin. Using previously reported δ(66)Zn values for anthropogenic emission from Europe, preliminary calculations suggest that up to 55% of Zn arriving at the sampling points in the equatorial eastern North Atlantic region could be of anthropogenic origin. PMID:23953448

  16. Satellite retrieval of aerosol microphysical and optical parameters using neural networks: a new methodology applied to the Sahara desert dust peak

    NASA Astrophysics Data System (ADS)

    Taylor, M.; Kazadzis, S.; Tsekeri, A.; Gkikas, A.; Amiridis, V.

    2013-12-01

    with only 39-45% of the data falling within the acceptable level of uncertainty relative to ground-truth data at the daily timescale. In the context of Saharan desert dust, this new methodological approach appears to offer some potential for moderately accurate daily retrieval of previously inaccessible aerosol parameters from space.

  17. New approaches to dust mitigation in the Antelope Valley

    SciTech Connect

    Farber, R.J.; Kim, B.M.; Grantz, D.A.; Vaughn, D.L.; Zink, T.; Skadberg, K.; Cowherd, C.; Grelinger, M.A.; Campbell, R.; De Salvio, A.; VanCuren, T.; Bort, J.

    1999-07-01

    The arid deserts of the southwestern US experience a frequent dust problem which can lead to PM10 violations. Blowing dust is also one of the major air quality problems of the arid deserts. From 1992 through the present, a group of research scientists have been investigating new techniques for mitigating the windblown dust in the Mojave Desert and more specifically the Antelope Valley near Palmdale and Lancaster, CA. This paper summarizes the progress made toward dust suppression in the Antelope Valley during the initial research phase from 1992 through 1996. During this period, there were both successes and failures. Stabilizing disturbed desert lands in a water-starved environment is challenging. The initial attempts focused on revegetation of native plants by seedings. There were mixed results depending on both the magnitude and timing of the rainfall. Various types of windfences were also erected and their effectiveness was studied using BSNE's. In the present program, the objectives have been broadened to include mitigating dust from all types of disturbed lands, not only abandoned farmlands. Techniques include new approaches to revegetation using seedlings, varying water treatments and soil amendments. An array of chemical suppressants are also being evaluated for cost-effectiveness as a function of longevity. Various geometries of wind fences have also been erected in blow sand areas and are being evaluated for cost-effectiveness using an interesting evaluation scheme. This portion of the paper provides a progress report of these latest dust mitigation techniques. This current research program is due to conclude about 2002. The end product of this decade research program will be a cookbook of dust mitigation solutions for various users including regulatory agencies, the USDA NRCS, farmers and construction interests.

  18. Long-term exposure to house dust mite leads to suppression of allergic airway disease despite persistent lung inflammation

    PubMed Central

    Bracken, Sonali J.; Adami, Alexander J.; Szczepanek, Steven M.; Ehsan, Mohsin; Natarajan, Prabitha; Guernsey, Linda A.; Shahriari, Neda; Rafti, Ektor; Matson, Adam P.; Schramm, Craig M.; Thrall, Roger S.

    2015-01-01

    Background Allergic asthma is a major cause of worldwide morbidity and results from inadequate immune regulation in response to innocuous, environmental antigens. The need exists to understand the mechanisms that promote non-reactivity to human-relevant allergens such as house dust mite (HDM) in order to develop curative therapies for asthma. The aim of our study was to compare the effects of short-, intermediate- and long-term HDM administration in a murine asthma model and determine the ability of long-term HDM exposure to suppress allergic inflammation. Methods C57BL/6 mice were intranasally instilled with HDM for short-term (2 weeks), intermediate-term (5 weeks) and long-term (11 weeks) periods to induce allergic airway disease (AAD). Severity of AAD was compared across all stages of the model via both immunologic and pulmonary parameters. Results Short- and intermediate-term HDM exposure stimulated development of AAD that included eosinophilia in the bronchoalveolar lavage fluid (BAL), pronounced airway hyper-reactivity (AHR), and evidence of lung inflammation. Long-term HDM exposure promoted suppression of AAD, with loss of BAL eosinophilia and AHR despite persistent mononuclear inflammation in the lungs. Suppression of AAD with long-term HDM exposure was associated with an increase in both Foxp3+ regulatory T cells and IL-10+ alveolar macrophages at the site of inflammation. Conclusions This model recapitulates key features of human asthma and may facilitate investigation into the mechanisms that promote immunological tolerance against clinically relevant aeroallergens. PMID:25924733

  19. Niamey Dust Observations

    DOE Data Explorer

    Flynn, Connor

    2008-10-01

    Niamey aerosol are composed of two main components: dust due to the proximity of the Sahara Desert, and soot from local and regional biomass burning. The purpose of this data product is to identify when the local conditions are dominated by the dust component so that the properties of the dust events can be further studied.

  20. The Desert Crossings of Mars

    NASA Astrophysics Data System (ADS)

    Cockell, C. S.

    Apart from the polar caps, the Martian volcanoes and the Valles Marineris, ~80% of the martian surface can essentially be classified as `desert'. The methods used to explore Mars, the scientific priorities and the philo- sophical and historical precedents that drive human exploration on Mars will primarily come from our experiences in terrestrial deserts. Here, the methods and approaches used for terrestrial desert expeditions are discussed with reference to Mars. Some of the physical challenges such as low temperature and frost formation will be akin to cold polar desert exploration on Earth. However, some challenges, such as dust storms and lack of liquid water will be akin to hot desert exploration. Expeditions that draw the appropriate lessons from both hot and cold desert terrestrial expeditions will succeed. Examples of major regions on Mars that might be regarded as significant exploratory challenges for expeditions are identified. Key parameters of these expeditions including distance and plausible scientific objectives are provided.

  1. Fate of Magnesium Chloride Brine Applied to Suppress Dust from Unpaved Roads at the INEEL Subsurface Disposal Area

    SciTech Connect

    Larry Hull; Carolyn Bishop

    2004-02-01

    Between 1984 and 1993, MgCl2 brine was used to suppress dust on unpaved roads at a radioactive waste subsurface disposal area. Because Cl– might enhance corrosion of buried metals in the waste, we investigated the distribution and fate of Cl– in the vadose zone using pore water samples collected from suction lysimeters and soluble salt concentrations extracted from sediment samples. The Cl/Br mass ratio and the total dissolved Cl– concentration of pore water show that brine contamination occurs primarily within 13 m of treated roads, but can extend as much as 30 m laterally in near-surface sedimentary deposits. Within the deep vadose zone, which consists of interlayered basalt lava flows and sedimentary interbeds, brine has moved up to 110 m laterally. This lateral migration suggests formation of perched water and horizontal transport during periods of high recharge. In a few locations, brine migrated to depths of 67 m within 3 to 5 yr. Elevated Cl– concentrations were found to depths of 2 m in roadbed material. In drainage ditches along roads, where runoff accumulates and recharge of surface water is high, Cl– was flushed from the sediments in 3 to 4 yr. In areas of lower recharge, Cl– remained in the sediments after 5 yr. Vertical brine movement is directly related to surface recharge through sediments. The distribution of Cl– in pore water and sediments is consistent with estimates of vadose zone residence times and spatial distribution of surface water recharge from other investigations at the subsurface

  2. Tradeoffs and synergies between biofuel production and large-scale solar infrastructure in deserts

    NASA Astrophysics Data System (ADS)

    Ravi, S.; Lobell, D. B.; Field, C. B.

    2012-12-01

    Solar energy installations in deserts are on the rise, fueled by technological advances and policy changes. Deserts, with a combination of high solar radiation and availability of large areas unusable for crop production are ideal locations for large scale solar installations. For efficient power generation, solar infrastructures require large amounts of water for operation (mostly for cleaning panels and dust suppression), leading to significant moisture additions to desert soil. A pertinent question is how to use the moisture inputs for sustainable agriculture/biofuel production. We investigated the water requirements for large solar infrastructures in North American deserts and explored the possibilities for integrating biofuel production with solar infrastructure. In co-located systems the possible decline in yields due to shading by solar panels may be offsetted by the benefits of periodic water addition to biofuel crops, simpler dust management and more efficient power generation in solar installations, and decreased impacts on natural habitats and scarce resources in deserts. In particular, we evaluated the potential to integrate solar infrastructure with biomass feedstocks that grow in arid and semi-arid lands (Agave Spp), which are found to produce high yields with minimal water inputs. To this end, we conducted detailed life cycle analysis for these coupled agave biofuel - solar energy systems to explore the tradeoffs and synergies, in the context of energy input-output, water use and carbon emissions.

  3. Desert dust deposition on Mt. Elbrus, Caucasus Mountains, Russia in 2009-2012 as recorded in snow and shallow ice core: high-resolution "provenancing", transport patterns, physical properties and soluble ionic composition

    NASA Astrophysics Data System (ADS)

    Kutuzov, S.; Shahgedanova, M.; Mikhalenko, V.; Lavrentiev, I.; Kemp, S.

    2013-04-01

    A record of dust deposition events between 2009 and 2012 on Mt. Elbrus, Caucasus Mountains derived from a snow pit and a shallow ice core is presented for the first time for this region. A combination of isotopic analysis, SEVIRI red-green-blue composite imagery, MODIS atmospheric optical depth fields derived using the Deep Blue algorithm, air mass trajectories derived using the HYSPLIT model and analysis of meteorological data enabled identification of dust source regions with high temporal (hours) and spatial (cf. 20-100 km) resolution. Seventeen dust deposition events were detected; fourteen occurred in March-June, one in February and two in October. Four events originated in the Sahara, predominantly in north-eastern Libya and eastern Algeria. Thirteen events originated in the Middle East, in the Syrian Desert and northern Mesopotamia, from a mixture of natural and anthropogenic sources. Dust transportation from Sahara was associated with vigorous Saharan depressions, strong surface winds in the source region and mid-tropospheric south-westerly flow with daily winds speeds of 20-30 m s-1 at 700 hPa level and, although these events were less frequent, they resulted in higher dust concentrations in snow. Dust transportation from the Middle East was associated with weaker depressions forming over the source region, high pressure centered over or extending towards the Caspian Sea and a weaker southerly or south-easterly flow towards the Caucasus Mountains with daily wind speeds of 12-18 m s-1 at 700 hPa level. Higher concentrations of nitrates and ammonium characterise dust from the Middle East deposited on Mt. Elbrus in 2009 indicating contribution of anthropogenic sources. The modal values of particle size distributions ranged between 1.98 μm and 4.16 μm. Most samples were characterised by modal values of 2.0-2.8 μm with an average of 2.6 μm and there was no significant difference between dust from the Sahara and the Middle East.

  4. An evaluation of an aftermarket local exhaust ventilation device for suppressing respirable dust and respirable crystalline silica dust from powered saws.

    PubMed

    Garcia, Alberto; Jones, Erica; Echt, Alan S; Hall, Ronald M

    2014-01-01

    The objective of this study was to quantify the respirable dust and respirable silica exposures of roofing workers using an electric-powered circular saw with an aftermarket local exhaust ventilation attachment to cut concrete roofing tiles. The study was conducted to determine whether the local exhaust ventilation attachment was able to control respirable dust and respirable silica exposure below occupational exposure limits (OELs). Time-integrated filter samples and direct reading respirable dust concentrations were evaluated. The local exhaust ventilation consisted of a shroud attached to the cutting plane of the saw; the shroud was then connected to a small electric axial fan, which is intended to collect dust at the point of generation. All sampling was conducted with the control in use. Roofers are defined as those individuals who only lay tiles. Cutters/roofers are defined as those workers who operate the powered saw to cut tiles and also lay tiles. Respirable dust from this evaluation ranged from 0.13 to 6.59 milligrams per cubic meter (mg/m(3)) with a geometric mean of 0.38 mg/m(3) for roofers and from 0.45 to 3.82 mg/m(3) with a geometric mean of 1.84 mg/m(3) for cutters/roofers. Cutters/roofers usually handle areas close to crevices, edges, or tips of the roof whereas roofers handle areas where complete tiles can be placed. The respirable dust exposures for all cutters/roofers indicated concentrations exceeding the Occupational Safety and Health Administration's (OSHA) permissible exposure limit (PEL) for respirable dust containing silica; it was also exceeded for some of the roofers. The respirable silica concentrations ranged from 0.04 to 0.15 mg/m(3) with a geometric mean of 0.09 mg/m(3) for roofers, and from 0.13 to 1.21 mg/m(3) with a geometric mean of 0.48 mg/m(3) for cutters/roofers. As with respirable dust, the respirable silica exposures for cutters/roofers were higher than the exposures for roofers. PMID:25148513

  5. An Evaluation of an Aftermarket Local Exhaust Ventilation Device for Suppressing Respirable Dust and Respirable Crystalline Silica Dust from Powered Saws

    PubMed Central

    Garcia, Alberto; Jones, Erica; Echt, Alan S.; Hall, Ronald M.

    2015-01-01

    The objective of this study was to quantify the respirable dust and respirable silica exposures of roofing workers using an electric powered circular saw with an aftermarket local exhaust ventilation attachment to cut concrete roofing tiles. The study was conducted to determine whether the local exhaust ventilation attachment was able to control respirable dust and respirable silica exposure below occupational exposure limits. Time-integrated filter samples and direct reading respirable dust concentrations were evaluated. The local exhaust ventilation consisted of a shroud attached to the cutting plane of the saw; the shroud was then connected to a small electric axial fan, which is intended to collect dust at the point of generation. All sampling was conducted with the control in use. Roofers are defined as those individuals who solely lay tiles. Cutters/roofers are defined as those workers who operate the powered saw to cut tiles and also lay tiles. Respirable dust from this evaluation ranged from 0.13 to 6.59 milligrams per cubic meter (mg/m3) with a geometric mean of 0.38 mg/m3 for roofers and from 0.45 to 3.82 mg/m3 with a geometric mean of 1.84 mg/m3 for cutters/roofers. Cutters/roofers usually handle areas close to crevices, edges, or tips of the roof whereas roofers handle areas where complete tiles can be placed. The respirable dust exposures for all cutters/roofers indicated concentrations exceeding the Occupational Safety and Health Administration’s (OSHA) permissible exposure limit (PEL) for respirable dust containing silica; it was also exceeded for some of the roofers. The respirable silica concentrations ranged from 0.04 to 0.15 mg/m3 with an average of 0.09 mg/m3 for roofers, and from 0.13 to 1.21 mg/m3 with an average of 0.48 mg/m3 for cutters/roofers. As with respirable dust, the respirable silica exposures to cutters/roofers were higher than the exposures for roofers. PMID:25148513

  6. Desert Sojourn.

    ERIC Educational Resources Information Center

    Greenman, Geri

    1999-01-01

    Focuses on an activity in which the students in a beginning drawing class used middle-value brown paper and earthen shades of conte to draw pictures of bones in a desert environment. Discusses how the assignment teaches appreciation of the colors, sounds, and shapes of the desert. (CMK)

  7. Desert Communities.

    ERIC Educational Resources Information Center

    NatureScope, 1985

    1985-01-01

    Provides: (1) background information on desert communities, their similarities, and differences; (2) student activities on this topic; and (3) ready-to-copy student pages with pictures of desert animals and plants. Each activity includes objective(s), recommended age level(s), subject area(s), list of materials needed, and procedures. (DH)

  8. The radiative impact of desert dust on orographic rain in the Cevennes-Vivarais area: a case study from HyMeX

    NASA Astrophysics Data System (ADS)

    Flamant, C.; Chaboureau, J.-P.; Chazette, P.; Di Girolamo, P.; Bourrianne, T.; Totems, J.; Cacciani, M.

    2015-08-01

    The study is focused on Intensive Observation Period (IOP) 14 of the Hydrology Cycle in the Mediterranean Experiment first Special Observing Period (HyMeX SOP 1) that took place from 17 to 19 October and was dedicated to the study of orographic rain in the Cevennes Vivarais (CV) target area. During this IOP a dense dust plume originating from North Africa (Maghreb and Sahara) was observed to be transported over the Balearic Islands towards the south of France. The plume was characterized by an aerosol optical depth between 0.2 and 0.8 at 550 nm, highly variable in time and space over the Western Mediterranean basin. The impact of this dust plume, the biggest event observed during the 2 month long HyMeX SOP 1, on the precipitation over the CV area has been analyzed using high resolution simulations from the convection permitting mesoscale model Meso-NH validated against measurements obtained from numerous instruments deployed specifically during SOP 1 (ground-based/airborne water vapor and aerosol lidars, airborne microphysics probes) as well as space-borne aerosol products. The 4 day simulation reproduced realistically the temporal and spatial variability (incl. vertical distribution) of the dust. The dust radiative impact led to an average 0.6 K heating at the altitude of the dust layer in the CV area (and up to +3 K locally) and an average 100 J kg-1 increase of most unstable convective available potential energy (and up to +900 J kg-1 locally) with respect to a simulation without prescribed dust aerosols. The rainfall amounts and location were only marginally affected by the dust radiative effect, even after 4 days of simulation. The transient nature of this radiative effect in dynamical environments such as those found in the vicinity of heavy precipitation events in the Mediterranean is not sufficient to impact 24 h accumulated rainfall in the dusty simulation.

  9. Dust, Climate, and Human Health

    NASA Technical Reports Server (NTRS)

    Maynard, Nancy G.

    2003-01-01

    Air pollution from both natural and anthropogenic causes is considered to be one of the most serious world-wide environment-related health problems, and is expected to become worse with changes in the global climate. Dust storms from the atmospheric transport of desert soil dust that has been lifted and carried by the winds - often over significant distances - have become an increasingly important emerging air quality issue for many populations. Recent studies have shown that the dust storms can cause significant health impacts from the dust itself as well as the accompanying pollutants, pesticides, metals, salt, plant debris, and other inorganic and organic materials, including viable microorganisms (bacteria, viruses and fungi). For example, thousands of tons of Asian desert sediments, some containing pesticides and herbicides from farming regions, are commonly transported into the Arctic during dust storm events. These chemicals have been identified in animal and human tissues among Arctic indigenous populations. Millions of tons of airborne desert dust are being tracked by satellite imagery, which clearly shows the magnitude as well as the temporal and spatial variability of dust storms across the "dust belt" regions of North Africa, the Middle East, and China. This paper summarizes the most recent findings on the effects of airborne desert dust on human health as well as potential climate influences on dust and health.

  10. Dust, Climate, and Human Health

    NASA Technical Reports Server (NTRS)

    Maynard, Nancy G.

    2003-01-01

    Air pollution from both natural and anthropogenic causes is considered to be one of the most serious world-wide environment-related health problems, and is expected to become worse with changes in the global climate. Dust storms from the atmospheric transport of desert soil dust that has been lifted and carried by the winds - often over significant distances - have become an increasingly important emerging air quality issue for many populations. Recent studies have shown that the dust storms can cause significant health impacts from the dust itself as well as the accompanying pollutants, pesticides, metals, salt, plant debris, and other inorganic and organic materials, including viable microorganisms (bacteria, viruses and fungi). For example, thousands of tons of Asian desert sediments, some containing pesticides and herbicides from farming regions, are commonly transported into the Arctic during dust storm events. These chemicals have been identified in animal and human tissues among Arctic indigenous populations. Millions of tons of airborne desert dust are being tracked by satellite imagery, which clearly shows the magnitude as well as the temporal and spatial variability of dust storms across the "dust belt" regions of North Africa, the Middle East, and China. Ths paper summarizes the most recent findings on the effects of airborne desert dust on human health as well as potential climate influences on dust and health.

  11. Dust, Climate, and Human Health

    NASA Astrophysics Data System (ADS)

    Maynard, N. G.

    2003-12-01

    Air pollution from both natural and anthropogenic causes is considered to be one of the most serious world-wide environment-related health problems, and is expected to become worse with changes in the global climate. Dust storms from the atmospheric transport of desert soil dust that has been lifted and carried by the winds - often over significant distances - have become an increasingly important emerging air quality issue for many populations. Recent studies have shown that the dust storms can cause significant health impacts from the dust itself as well as the accompanying pollutants, pesticides, metals, salt, plant debris, and other inorganic and organic materials, including viable microorganisms (bacteria, viruses and fungi). For example, thousands of tons of Asian desert sediments, some containing pesticides and herbicides from farming regions, are commonly transported into the Arctic during dust storm events. These chemicals have been identified in animal and human tissues among Arctic indigenous populations. Millions of tons of airborne desert dust are being tracked by satellite imagery, which clearly shows the magnitude as well as the temporal and spatial variability of dust storms across the "dust belt" regions of North Africa, the Middle East, and China. This paper summarizes the most recent findings on the effects of airborne desert dust on human health as well as potential climate influences on dust and health

  12. Wind tunnel tests of biodegradable fugitive dust suppressants being considered to reduce soil erosion by wind at radioactive waste construction sites

    SciTech Connect

    Ligotke, M.W.; Dennis, G.W.; Bushaw, L.L.

    1993-10-01

    Wind tunnel tests were performed of three fugitive dust control agents derived from potato and sugar beet products. These materials are being considered for use as dust suppressants to reduce the potential for transport of radioactive materials by wind from radioactive waste construction and remediation sites. Soil and dust control agent type, solution concentrations, application quantities, aging (or drying) conditions, surface disturbance, and wind and saltating sand eolian erosive stresses were selected and controlled to simulate application and exposure of excavated soil surfaces in the field. A description of the tests, results, conclusions, and recommendations are presented in this report. The results of this study indicate that all three dust control agents can protect exposed soil surfaces from extreme eolian stresses. It is also clear that the interaction and performance of each agent with various soil types may differ dramatically. Thus, soils similar to that received from ML should be best protected by high concentration ({approximately}2.5%) solutions of potato starch at low water application levels ({approximately}1 to 2 L/m{sup 2}). Because the effectiveness of PS on this soil type is degraded after a moderate amount of simulated rainfall, other options or additives should be considered if surfaces are to be protected for long intervals or during periods of intermittent rainfall and hot, windy conditions. On the other hand, XDCA should be considered when excavating sandy soils. It should be noted, however, that because the Hanford soil test results are based on a small number of tests, it would be prudent to perform additional tests prior to selecting a fugitive dust control agent for use at the Hanford Site. While fermented potato waste was not the best fixative used on either soil, it did perform reasonably well on both soil types (better than XDCA on Idaho soil and better than PS on Hanford soil).

  13. The radiative impact of desert dust on orographic rain in the Cévennes-Vivarais area: a case study from HyMeX

    NASA Astrophysics Data System (ADS)

    Flamant, C.; Chaboureau, J.-P.; Chazette, P.; Di Girolamo, P.; Bourrianne, T.; Totems, J.; Cacciani, M.

    2015-11-01

    The study is focused on Intensive Observation Period (IOP) 14 of the Hydrological Cycle in the Mediterranean Experiment first Special Observing Period (HyMeX SOP 1) that took place from 17 to 19 October 2012 and was dedicated to the study of orographic rain in the Cévennes-Vivarais (CV) target area. During this IOP a dense dust plume originating from northern Africa (the Maghreb and Sahara) was observed to be transported over the Balearic Islands towards the south of France. The plume was characterized by an aerosol optical depth between 0.2 and 0.8 at 550 nm, highly variable in time and space over the western Mediterranean Basin. The impact of this dust plume, the biggest event observed during the 2-month-long HyMeX SOP 1, on the precipitation over the CV area has been analyzed using high-resolution simulations from the convection permitting mesoscale model Meso-NH (mesoscale non-hydrostatic model) validated against measurements obtained from numerous instruments deployed specifically during SOP 1 (ground-based/airborne water vapor and aerosol lidars, airborne microphysics probes) as well as space-borne aerosol products. The 4-day simulation reproduced realistically the temporal and spatial variability (including the vertical distribution) of the dust. The dust radiative impact led to an average 0.6 K heating at the altitude of the dust layer in the CV area (and up to +3 K locally) and an average 100 J kg-1 increase of most unstable convective available potential energy (and up to +900 J kg-1 locally) with respect to a simulation without prescribed dust aerosols. The rainfall amounts and location were only marginally affected by the dust radiative effect, even after 4 days of simulation. The transient nature of this radiative effect in dynamical environments such as those found in the vicinity of heavy precipitation events in the Mediterranean is not sufficient to impact 24 h of accumulated rainfall in the dust simulation.

  14. Application of a Broad-Range Resequencing Array for Detection of Pathogens in Desert Dust Samples from Kuwait and Iraq ▿

    PubMed Central

    Leski, Tomasz A.; Malanoski, Anthony P.; Gregory, Michael J.; Lin, Baochuan; Stenger, David A.

    2011-01-01

    A significant percentage of the human population is exposed to high levels of naturally occurring airborne dusts. Although the link between airborne particulate inhalation and a variety of respiratory diseases has long been established, little is known about the pathogenic role of the microbial component of the dust. In this study, we applied highly multiplexed PCR and a high-density resequencing microarray (RPM-TEI version 1.0) to screen samples of fine topsoil particles and airborne dust collected in 19 locations in Iraq and Kuwait for the presence of a broad range of human pathogens. The results indicated the presence of potential human pathogens, including Mycobacterium, Brucella, Coxiella burnetii, Clostridium perfringens, and Bacillus. The presence of Coxiella burnetii, a highly infectious potential biowarfare agent, was confirmed and detected in additional samples by use of a more sensitive technique (real-time PCR), indicating a high prevalence of this organism in the analyzed samples. The detection of potentially viable pathogens in breathable dusts from arid regions of Iraq and Kuwait underscores the importance of further study of these environments. PMID:21571877

  15. Distribution of desert varnish in Arizona

    NASA Technical Reports Server (NTRS)

    Elvidge, Christopher D.

    1989-01-01

    Desert varnish is the dark coat of clay and ferromanganese oxides developed on exposed rock surfaces in arid regions. It forms from the accretion of material from windblown dust. The distribution of desert varnish was mapped in Arizona. It was discovered that desert varnish could be mapped on a regional scale. Well developed desert varnish is common on stable rock surfaces in areas having alkaline soils and less than about 25 cm of annual precipitation. Rock surfaces in areas having more than 40 cm of annual precipitation are generally devoid of desert varnish. An experiment was conducted with varnished desert pavement stone. The stones were broken in half and half was set on a roof in central Illinois from April until October. Removed from the alkaline desert environment, it only took seven months for the varnish to develop an eroded appearance. This experiment graphically illustrates the dependency of desert varnish on alkalinity. In this context, the zones of eroded desert varnish in Arizona indicate that the area of active desert varnish formation has fluctuated, expanding in drier times and contracting/eroding in wetter times.

  16. Thar Desert

    NASA Technical Reports Server (NTRS)

    2001-01-01

    This ASTER sub-scene covers an area of 12 x 15 km in NW India in the Thar Desert. The sand dunes of the Thar Desert constantly shift and take on new shapes. Located in northwestern India and eastern Pakistan, the desert is bounded on the south by a salt marsh known as the Rann of Kutch, and on the west by the Indus River plain. About 800 kilometers long and about 490 kilometers wide, the desert's terrain is mainly rolling sandhills with scattered growths of shrub and rock outcroppings. Only about 12 to 25 centimeters of rain fall on the desert each year, and temperatures rise as high as 52 degrees Celsius. Much of the population is pastoral, raising sheep for their wool. The image is located at 24.4 degrees north latitude and 69.3 degrees east longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  17. Desert Survivors!

    ERIC Educational Resources Information Center

    Horton, Jessica; Friedenstab, Steve

    2013-01-01

    This article describes a special third-grade classroom unit based on the reality show "Survivor." The goal of this engaging and interactive unit was to teach students about physical and behavioral adaptations that help animals survive in various desert biomes. The activity combines research, argument, and puppet play over one week of…

  18. Discovering Deserts.

    ERIC Educational Resources Information Center

    Braus, Judy, Ed.

    1985-01-01

    Ranger Rick's NatureScope is a creative education series dedicated to inspiring in children an understanding and appreciation of the natural world while developing the skills they will need to make responsible decisions about the environment. The topic of this issue is "Discovering Deserts." Contents are organized into the following sections: (1)…

  19. Satellite retrieval of aerosol microphysical and optical parameters using neural networks: a new methodology applied to the Sahara desert dust peak

    NASA Astrophysics Data System (ADS)

    Taylor, M.; Kazadzis, S.; Tsekeri, A.; Gkikas, A.; Amiridis, V.

    2014-09-01

    In order to exploit the full-earth viewing potential of satellite instruments to globally characterise aerosols, new algorithms are required to deduce key microphysical parameters like the particle size distribution and optical parameters associated with scattering and absorption from space remote sensing data. Here, a methodology based on neural networks is developed to retrieve such parameters from satellite inputs and to validate them with ground-based remote sensing data. For key combinations of input variables available from the MODerate resolution Imaging Spectro-radiometer (MODIS) and the Ozone Measuring Instrument (OMI) Level 3 data sets, a grid of 100 feed-forward neural network architectures is produced, each having a different number of neurons and training proportion. The networks are trained with principal components accounting for 98% of the variance of the inputs together with principal components formed from 38 AErosol RObotic NETwork (AERONET) Level 2.0 (Version 2) retrieved parameters as outputs. Daily averaged, co-located and synchronous data drawn from a cluster of AERONET sites centred on the peak of dust extinction in Northern Africa is used for network training and validation, and the optimal network architecture for each input parameter combination is identified with reference to the lowest mean squared error. The trained networks are then fed with unseen data at the coastal dust site Dakar to test their simulation performance. A neural network (NN), trained with co-located and synchronous satellite inputs comprising three aerosol optical depth measurements at 470, 550 and 660 nm, plus the columnar water vapour (from MODIS) and the modelled absorption aerosol optical depth at 500 nm (from OMI), was able to simultaneously retrieve the daily averaged size distribution, the coarse mode volume, the imaginary part of the complex refractive index, and the spectral single scattering albedo - with moderate precision: correlation coefficients in the

  20. Dust storms - Great Plains, Africa, and Mars

    NASA Technical Reports Server (NTRS)

    Woiceshyn, P. M.; Krauss, R.; Minzner, R.; Shenk, W.

    1977-01-01

    Dust storms in the Great Plains of North America and in the Sahara Desert are analyzed on the basis of imagery from the geostationary Synchronous Meteorological Satellite. The onset time, location and areal extent of the dust storms are studied. Over land surfaces, contrast enhancement techniques are needed to obtain an adequate picture of dust storm development. In addition, infrared imagery may provide a means of monitoring the strong horizontal temperature gradients characteristic of dust cloud boundaries. Analogies between terrestrial dust storms and the airborne rivers of dust created by major Martian dust storms are also drawn.

  1. Decreased Pulmonary Function in School Children in Western Japan after Exposures to Asian Desert Dusts and Its Association with Interleukin-8

    PubMed Central

    Watanabe, Masanari; Kurai, Jun; Sano, Hiroyuki; Saito, Rumiko; Kimura, Yutaka; Aiba, Setsuya; Oshimura, Mitsuo; Yamasaki, Akira; Shimizu, Eiji

    2015-01-01

    The objective of the study was to investigate the influence of Asian dust storms (ADS) on pulmonary function of school children and the relationship of this effect with interleukin-8. Morning peak expiratory flow (PEF) was measured daily in 399 children from April to May 2012 and in 384 of these children from March to May 2013. The data were analyzed for an association between ADS events and PEF by linear mixed models. Interleukin-8 transcriptional activity was assessed in THP-G8 cells stimulated by airborne particles collected on ADS days. Seven ADS days were identified: April 23 and 24, 2012; March 8 to 10, 2013; and March 19 and 20, 2013. Changes in PEF after ADS exposure were −8.17 L/min (95% confidence interval, −11.40 to −4.93) in 2012 and −1.17 L/min (−4.07 to 1.74) in 2013, and there was a significant difference between 2012 and 2013. Interleukin-8 transcriptional activity was significantly higher in 2012 at 10.6 ± 2.9-fold compared to 3.7 ± 0.4 in March 8 to 10, 2013, and 2.3 ± 0.2 in March 19 and 20, 2013. The influence of ADS events on pulmonary function of children differs with each ADS event and may be related to interleukin-8 production. PMID:26060816

  2. Exozodiacal dust

    NASA Astrophysics Data System (ADS)

    Kuchner, Marc Jason

    Besides the sun, the most luminous feature of the solar system is a cloud of "zodiacal" dust released by asteroids and comets that pervades the region interior to the asteroid belt. Similar clouds of dust around other stars---exozodiacal clouds---may be the best tracers of the habitable zones of extra-solar planetary systems. This thesis discusses three searches for exozodiacal dust: (1) We observed six nearby main-sequence stars with the Keck telescope at 11.6 microns, correcting for atmosphere-induced wavefront aberrations and deconvolving the point spread function via classical speckle analysis. We compare our data to a simple model of the zodiacal dust in our own system based on COBE DIRBE observations and place upper limits on the density of exozodiacal dust in these systems. (2) We observed Sirius, Altair, and Procyon with the NICMOS Coronagraph on the Hubble Space Telescope to look for scattered light from exozodiacal dust and faint companions within 10 AU from these stars. (3) The planned nulling capability of the Keck Interferometer should allow it to probe the region <200 milliarcsecond from a bright star and to suppress on-axis starlight by factors of 10 -3 to reveal faint circumstellar material. We model the response of the Keck Interferometer to hypothetical exozodiacal clouds to derive detection limits that account for the effects of stellar leakage, photon noise, noise from null depth fluctuations, and the fact that the cloud's shape is not known a priori. We also discuss the interaction of dust with planets. We used the COBE DIRBE Sky and Zodi Atlas and the IRAS Sky Survey Atlas to search for dynamical signatures of three different planets in the solar system dust complex: (1) We searched the COBE DIRBE Sky and Zodi Atlas for a wake of dust trailing Mars. We compare the DIRBE images to a model Mars wake based on the empirical model of the Earth's wake as seen by the DIRBE. (2) We searched the COBE DIRRE Sky and Zodi Atlas for Tiojan dust near

  3. Desert dust induces TLR signaling to trigger Th2-dominant lung allergic inflammation via a MyD88-dependent signaling pathway.

    PubMed

    He, Miao; Ichinose, Takamichi; Song, Yuan; Yoshida, Yasuhiro; Bekki, Kanae; Arashidani, Keiichi; Yoshida, Seiichi; Nishikawa, Masataka; Takano, Hirohisa; Shibamoto, Takayuki; Sun, Guifan

    2016-04-01

    Asian sand dust (ASD) is known to exacerbate asthma, although its mechanism is not yet well understood. In this study, when the effects on inflammatory response by LPS present in ASD was investigated by measuring the gene expression of cytokines and chemokines in RAW264.7 cells treated with ASD and/or polymyxin B (PMB), the ASD effects were attenuated by PMB, but not completely. When an in vitro study was performed using bone marrow-derived macrophages (BMDMs) from WT, TLR2(-/-), TLR4(-/-), and MyD88(-/-) BALB/c mice and BMDMs from WT, TLR2(-/-), TLR4(-/-), TLR2/4(-/-), TLR7/9(-/-), and MyD88(-/-) C57BL/6J mice, cytokine (IL-6, IL-12) production in BMDMs was higher in ASD-stimulated TLR2(-/-) cells than in TLR4(-/-) cells, whereas it was lower or undetectable in TLR2/4(-/-) and MyD88(-/-) cells. These results suggest that ASD causes cytokine production predominantly in a TLR4/MyD88-dependent pathway. When WT and TLRs 2(-/-), 4(-/-), and MyD88(-/-) BALB/c mice were intratracheally challenged with OVA and/or ASD, ASD caused exacerbation of lung eosinophilia along with Th2 cytokine and eosinophil-relevant chemokine production. Serum OVA-specific IgE and IgG1 similar to WT was observed in TLRs 2(-/-), 4(-/-) mice, but not in MyD88(-/-) mice. The Th2 responses in TLR2(-/-) mice were attenuated remarkably by PMB. These results indicate that ASD exacerbates lung eosinophilia in a MyD88-dependent pathway. TLRs 2 and 4 signaling may be important in the increase in lung eosinophilia. Also, the TLR4 ligand LPS and TLR2 ligand like β-glucan may be strong candidates for exacerbation of lung eosinophilia. PMID:26882889

  4. Toxoplasma gondii Infection Suppresses House Dust Mite Extract-Induced Atopic Dermatitis in NC/Nga Mice

    PubMed Central

    Jeong, Young-Il; Hong, Sung-Hee; Cho, Shin-Hyeong; Lee, Won-Ja

    2015-01-01

    Purpose Toxoplasma gondii (T. gondii) is an obligate intracellular protozoan parasite that infects humans and animals via congenital or postnatal routes, and it is found worldwide. Modulation of the immune system by parasite infection is proposed to suppress allergic inflammation. Growing evidences have shown that interleukin (IL)-10-producing regulatory B cells (Bregs) and CD4+CD25+FoxP3+ regulatory T cells (Tregs) induced by parasite infection play a critical role in allergic or autoimmune diseases because these cells regulate negatively cellular immune responses and inflammation. Currently, the role of IL-10-producing regulatory B cells in host immune response during T. gondii infection is unknown. In this study, we investigate whether T. gondii infection can suppress the development of unrelated atopic dermatitis (AD)-like lesions. Methods AD is a chronically relapsing inflammatory skin disease accompanied by severe itching; for this, we used NC/Nga mice, a well-known experimental model of systemic AD. Repeated exposure to Dermatophagoides farinae crude extract (DfE), known as a major environmental allergen, evokes AD-like skin lesions in NC/Nga mice under specific pathogen-free conditions. NC/Nga mice were intraperitoneally infected with 10 cysts of T. gondii. Results T. gondii infection significantly ameliorated AD-like skin lesions in NC/Nga mice. The subpopulation of Bregs and Tregs in the AD mice was expanded in the course of T. gondii infection. In addition, T. gondii infection inhibited Th2 and enhanced Th1 immune response in the DfE-treated AD mice. Conclusions We have experimentally demonstrated for the first time that T. gondii infection ameliorated AD-like skin lesions in a mouse model of AD. Our study could in part explain the mechanisms of how parasite infection prevents the development of allergic disorder. Therefore, these immunemechanisms induced by T. gondii infection may be beneficial for the host in terms of reduced risk of allergic immune

  5. Differences in allergic inflammatory responses between urban PM2.5 and fine particle derived from desert-dust in murine lungs.

    PubMed

    He, Miao; Ichinose, Takamichi; Kobayashi, Makoto; Arashidani, Keiichi; Yoshida, Seiichi; Nishikawa, Masataka; Takano, Hirohisa; Sun, Guifan; Shibamoto, Takayuki

    2016-04-15

    The biological and chemical natures of materials adsorbed onto fine particulate matter (PM2.5) vary by origin and passage routes. The exacerbating effects of the two samples-urban PM2.5 (U-PM2.5) collected during the hazy weather in a Chinese city and fine particles (ASD-PM2.5) collected during Asian sand dust (ASD) storm event days in Japan-on murine lung eosinophilia were compared to clarify the role of toxic materials in PM2.5. The amounts of β-glucan and mineral components were higher in ASD-PM2.5 than in U-PM2.5. On the other hand, organic chemicals, including polycyclic aromatic hydrocarbons (PAHs), were higher in U-PM2.5 than in ASD-PM2.5. When BALB/c mice were intratracheally instilled with U-PM2.5 and ASD-PM2.5 (total 0.4 mg/mouse) with or without ovalbumin (OVA), various biological effects were observed, including enhancement of eosinophil recruitment induced by OVA in the submucosa of the airway, goblet cell proliferation in the bronchial epithelium, synergic increase of OVA-induced eosinophil-relevant cytokines and a chemokine in bronchoalveolar lavage fluid, and increase of serum OVA-specific IgG1 and IgE. Data demonstrate that U-PM2.5 and ASD-PM2.5 induced allergic inflammatory changes and caused lung pathology. U-PM2.5 and ASD-PM2.5 increased F4/80(+) CD11b(+) cells, indicating that an influx of inflammatory and exudative macrophages in lung tissue had occurred. The ratio of CD206 positive F4/80(+) CD11b(+) cells (M2 macrophages) in lung tissue was higher in the OVA+ASD-PM2.5 treated mice than in the OVA+U-PM2.5 treated mice. These results suggest that the lung eosinophilia exacerbated by both PM2.5 is due to activation of a Th2-associated immune response along with induced M2 macrophages and the exacerbating effect is greater in microbial element (β-glucan)-rich ASD-PM2.5 than in organic chemical-rich U-PM2.5. PMID:26917405

  6. Inventory of African desert dust events in the north-central Iberian Peninsula in 2003-2014 based on sun-photometer-AERONET and particulate-mass-EMEP data

    NASA Astrophysics Data System (ADS)

    Cachorro, Victoria E.; Burgos, Maria A.; Mateos, David; Toledano, Carlos; Bennouna, Yasmine; Torres, Benjamín; de Frutos, Ángel M.; Herguedas, Álvaro

    2016-07-01

    A reliable identification of desert dust (DD) episodes over north-central Spain is carried out based on the AErosol RObotic NETwork (AERONET) columnar aerosol sun photometer (aerosol optical depth, AOD, and Ångström exponent, α) and European Monitoring and Evaluation Programme (EMEP) surface particulate-mass concentration (PMx, x = 10, 2.5, and 2.5-10 µm) as the main core data. The impact of DD on background aerosol conditions is detectable by means of aerosol load thresholds and complementary information provided by HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory Model) air mass back trajectories, MODIS (Moderate Resolution Imaging Spectroradiometer) images, forecast aerosol models, and synoptic maps, which have been carefully reviewed by a human observer for each day included in the DD inventory. This identification method allows the detection of low and moderate DD intrusions and also of mixtures of mineral dust with other aerosol types by means of the analysis of α. During the period studied (2003-2014), a total of 152 DD episodes composed of 418 days are identified. Overall, this means ˜ 13 episodes and ˜ 35 days per year with DD intrusion, representing 9.5 % days year-1. During the identified DD intrusions, 19 daily exceedances over 50 µg m-3 are reported at the surface. The occurrence of DD event days during the year peaks in March and June, with a marked minimum in April and lowest occurrence in winter. A large interannual variability is observed showing a statistically significant temporal decreasing trend of ˜ 3 days year-1. The DD impact on the aerosol climatology is addressed by evaluating the DD contribution in magnitude and percent (in brackets) for AOD, PM10, PM2.5, and PM2.5 - 10, obtaining mean values of 0.015 (11.5 %), 1.3 µg m-3 (11.8 %), 0.55 µg m-3 (8.5 %) and 0.79 µg m-3 (16.1 %), respectively. Annual cycles of the DD contribution for AOD and PM10 present two maxima - one in summer (0.03 and 2.4 µg m-3 for AOD in

  7. What Makes a Desert a Desert?

    ERIC Educational Resources Information Center

    NatureScope, 1985

    1985-01-01

    Presents background information and activities which focus on definition of a desert, locations of deserts, and factors influencing locations. Activities include objective(s), recommended age level(s), subject area(s), list of materials needed, and procedures. Two ready-to-copy pages with desert landforms and temperature/rainfall data are…

  8. The Hot-Water Extract of Smilacis Chinae Rhizome Suppresses 2,4-Dinitrochlorobenzene and House Dust Mite-Induced Atopic Dermatitis-Like Skin Lesions in Mice.

    PubMed

    Ki, Nam Yong; Park, Eun-Ji; Sung, In Sung; Ju, Seul A; Kim, Kyoung Un; Kim, Mi Rae; Song, Do Yeon; Lee, Min-Ju; Kim, Hak-Soo; Kang, Boo-Hyon; Chung, Hun-Jong; Choi, Eun-Ju; Yoon, Ki-Hun; Lee, Min Won; Yun, Seongho; Min, Bokkee; Kwon, Suk Hyung; Shin, Hwa-Sup

    2016-04-01

    Smilacis Chinae Rhizome (SCR) has been used as an oriental folk medicine for various biological activities. However, its effect on atopic dermatitis (AD) remains undetermined to date. We assessed the effect of orally administered hot-water extract of SCR on AD-like skin lesions in mice and its underlying mechanisms. AD-like murine model was prepared by repeated alternate application of house dust mite (Dermatophagoides farinae) extract (DFE) and 2,4-dinitrochlorobenzene (DNCB) for 4 weeks, topically to the ears. Daily oral administration of SCR for 3 and 4 weeks significantly reduced inflammatory ear thickening, with the effect being enhanced at the earlier start and longer period of administration. This effect was accompanied by a significant decrease in both Th2 and Th1 serum antibodies (total IgE, DFE-specific IgE, and IgG2a). Histological analysis showed that SCR markedly decreased the epidermal/dermal ear thickening and the dermal infiltration of inflammatory cells. Furthermore, SCR suppressed DFE/DNCB-induced expression of IL-4, IL-13, IL-17, IL-18, TSLP, and IFN-γ genes in the ear tissue. Taken together, our observations demonstrate that chronic oral administration of SCR exerts beneficial effect in mouse AD model, suggesting that SCR has the therapeutic potential as an orally active treatment of AD by modulating both Th1 and Th2 responses. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26840656

  9. Desert Research and Technology Studies Exposure of Lotus Coated Electrodynamic Shield Samples

    NASA Technical Reports Server (NTRS)

    Rodriquez, Marcello; Peters, Wanda C.; Straka, Sharon A.; Jones, Craig B.

    2011-01-01

    The Lotus dust mitigation coating and the electrodynamic shield (EDS) are two new technologies currently being developed by NASA as countermeasures for addressing dust accumulation for long-duration human space exploration. These combined technologies were chosen by the Habitation Demonstration Unit (HDU) program for desert dust exposure at the Desert Research and Technologies Studies (D-RaTS) test site in Arizona. Characterization of these samples was performed prior to, during and post D-RaTS exposure.

  10. Characterization of ice nucleation on different natural dust samples

    NASA Astrophysics Data System (ADS)

    Kaufmann, Lukas; Hofer, Julian; Marcolli, Claudia; Pinti, Valeria; Hoyle, Christopher; Peter, Thomas

    2014-05-01

    The impact of aerosols on Earth's climate is still uncertain. Therefore a better understanding of direct and indirect effects of aerosols is essential to improve models and the ability to predict future climate change. A natural source of aerosols is desert dust. Laboratory measurements investigating the influence of dust on heterogeneous freezing of water droplets are presented. We performed measurements with seven dust samples collected in the Etosha pan in Namibia, in the Makgadikgadi pan in Botswana (from three different locations), on the Altiplano in Bolivia, in Qatar and in the Hoggar mountains in Algeria. After sieving, the particle diameters of these dusts were < 32 μm. The mineralogical composition of the dusts was determined by X-ray diffraction. For the investigation of the ice nucleation ability of these dusts, emulsion as well as bulk freezing measurements were performed with a differential scanning calorimeter (DSC). For the emulsion measurements a suspension of a dust was mixed with water. Mixed with a mineral oil/lanolin mixture, the water droplets in the emulsion had mean diameters of around 2 μm. Heterogeneous freezing of dusts was characterized by three temperatures for frozen fractions of 0.1, 0.25, and 0.5, respectively. Heterogeneous freezing temperatures for all 7 samples were quite similar, namely 245 - 246.5 K (for frozen fractions of 0.1), 243 - 244.5 K (for 0.25) and 240 - 241.5 K (for 0.5). Emulsions consisting of pure water suspensions froze with onset temperatures of around 237 K. Emulsion measurements with Hoggar mountain dust were also performed with an additional solute such as ammonium sulfate, malonic acid, glucose or PEG 300. Immersion freezing was found to be suppressed in the presence of solutes. For the bulk measurements dusts were suspended in pure water and droplets with radii of about 1 mm were subjected to repeated freezing cycles. Freezing temperatures in the range of 253 - 265 K were found for cooling rates of 10 K

  11. Aerosol direct radiative forcing in desert and semi-desert regions of northwestern China

    NASA Astrophysics Data System (ADS)

    Xin, Jinyuan; Gong, Chongshui; Wang, Shigong; Wang, Yuesi

    2016-05-01

    The optical properties of dust aerosols were measured using narrow-band data from a portable sun photometer at four desert and semi-desert stations in northwestern China from 2004 to 2007. Ground-based and satellite observations indicated absorbing dust aerosol loading over the region surrounded by eight large-scale deserts. Radiation forcing was identified by using the Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model. The ranges of annual mean aerosol optical depth (AOD), Angström exponents, and single-scattering albedo (SSA) were from 0.25 to 0.35, from - 0.73 to 1.18, and from 0.77 to 0.86, respectively. The ranges of annual mean aerosol direct radiative forcing values at the top of the atmosphere (TOA), mid-atmosphere, and on the surface were from 3.9 to 12.0, from 50.0 to 53.1, and from - 39.1 to - 48.1 W/m2, respectively. The aerosols' optical properties and radiative characteristics showed strong seasonal variations in both the desert and semi-desert regions. Strong winds and relatively low humidity will lead dust aerosols in the atmosphere to an increase, which played greatly affected these optical properties during spring and winter in northwestern China. Based on long-term observations and retrieved data, aerosol direct radiative forcing was confirmed to heat the atmosphere (50-53 W/m2) and cool the surface (- 39 to - 48 W/m2) above the analyzed desert. Radiative forcing in the atmosphere in spring and winter was 18 to 21 W/m2 higher than other two seasons. Based on the dust sources around the sites, the greater the AOD, the more negative the forcing. The annual averaged heating rates for aerosols close to the ground (1 km) were approximately 0.80-0.85 K/day.

  12. Sources of Asian dust and role of climate change versus desertification in Asian dust emission

    NASA Astrophysics Data System (ADS)

    Zhang, X. Y.; Gong, S. L.; Zhao, T. L.; Arimoto, R.; Wang, Y. Q.; Zhou, Z. J.

    2003-12-01

    Simulations of Asian dust emissions over the past 43 years are presented based on a size-dependent soil dust emission and transport model (NARCM) along with supporting data from a network of surface stations. The deserts in Mongolia and in western and northern China (mainly the Taklimakan and Badain Juran, respectively) contribute ~70% of the total dust emissions; non-Chinese sources account for ~40% of this. Several areas, especially the Onqin Daga sandy land, Horqin sandy land, and Mu Us Desert, have increased in dust emissions over the past 20 years, but efforts to reduce desertification in these areas may have little effect on Asian dust emission amount because these are not key sources. The model simulations indicate that meteorology and climate have had a greater influence on the Asian dust emissions and associated Asian dust storm occurrences than desertification.

  13. Desert Voices: Southwestern Children's Literature.

    ERIC Educational Resources Information Center

    Polette, Keith

    1997-01-01

    Examines three books with different ways of writing about the desert. Discusses: "Here Is the Southwestern Desert" by Madeline Dunphy, "The Desert Is My Mother" by Pat Mora, and "The Desert Mermaid" by Alberto Blanco. (PA)

  14. Dust events, pulmonary diseases and immune system

    PubMed Central

    Esmaeil, Nafiseh; Gharagozloo, Marjan; Rezaei, Abbas; Grunig, Gabriele

    2014-01-01

    Incidences of sand storms have increased in recent years and there is evidence that these dusts can move across long distances. Sand dusts have different adverse effects on health, but one of the most important of them is pulmonary disease. After inhalation of dust, many dust particles are moved to the airways. Dust particles can be sensed by airways epithelial cells, activate macrophages, dendritic cells and innate immune cells and then initiate responses in various populations of specific immune cells such as T helper cells subsets (Th1, Th2, Th17), T cytotoxic cells and B cells. Initiation of inflammatory immune responses, activation of immune cells and releases of many cytokines, chemokines and other inflammatory molecules, have variable pathologic affects on lung in different respiratory diseases. Unfortunately control of desert dusts is more difficult than control of air pollution. For prevention and treatment of respiratory diseases that are caused by desert dusts, researchers need well-designed epidemiological studies, combined with analysis of the precise composition of sand dusts, and the precise mechanisms of the immune responses. Recognizing the exact cellular and molecular immune mechanisms would be very useful to find new approaches for treatment of desert dust associated pulmonary diseases. PMID:24660118

  15. Ground/satellite observations and atmospheric modeling of dust storms originating in the high Puna-Altiplano deserts (South America): Implications for the interpretation of paleo-climatic archives

    NASA Astrophysics Data System (ADS)

    Gaiero, D. M.; Simonella, L.; Gassó, S.; Gili, S.; Stein, A. F.; Sosa, P.; Becchio, R.; Arce, J.; Marelli, H.

    2013-05-01

    This study provides a detailed description of the sources, transport, dispersion, and deposition of two major dust events originating from the high-altitude subtropical Puna-Altiplano Plateau (15-26°S; 65-69°W) in South America. A long and severe drought provided the right conditions for the onset of both events in July 2009 and 2010. Dust was transported SE and deposited over the Pampas region and was observed to continue to the Atlantic Ocean. Dust monitoring stations located downwind recorded both events, and samples were characterized through chemical and textural analysis. Through a combination of meteorological data and satellite observations (CALIPSO and MODIS detectors), we estimate the emission flux for the 2010 event. This estimate was used to constrain the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) transport model and simulate the dust event. Both satellite imagery and model results agree in the location and extension of the dust cloud. CALIPSO detected dust between ~6000 and ~8500 m a.s.l., which remained at this height during most of its trajectory. The dust cloud mixed with a strong convective system in the region, and the associated precipitation brought down significant amounts of dust to the ground. Dust particle size analysis for both events indicates that near the sources dust samples show median modes of 12.4-14.1 µm, similar to modes observed 1300 km away. Chemical composition of sediments from potential dust sources shows distinct signatures within the Puna-Altiplano Plateau, the Puna sector being clearly different from the Altiplano area. In addition, both sources are markedly different from the Patagonian chemical fingerprint. These results have important implications to improve the interpretation of paleo-environmental archives preserved on the Argentine loess, Antarctic ice cores, and Southern Ocean marine sediments.

  16. Dust storm off Western Africa

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The impacts of Saharan dust storms reach far beyond Africa. Wind-swept deserts spill airborne dust particles out over the Atlantic Ocean where they can enter trade winds bound for Central and North America and the Caribbean. This Moderate Resolution Imaging Spectroradiometer (MODIS) image shows a dust storm casting an opaque cloud of cloud across the Canary Islands and the Atlantic Ocean west of Africa on June 30, 2002. In general it takes between 5 and 7 days for such an event to cross the Atlantic. The dust has been shown to introduce foreign bacteria and fungi that have damaged reef ecosystems and have even been hypothesized as a cause of increasing occurrences of respiratory complaints in places like Florida, where the amount of Saharan dust reaching the state has been increasing over the past 25 years.

  17. Saharan Dust over the Atlantic

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Fierce winds ripped across the Sahara Desert this past weekend and blew a large plume of dust out over the Atlantic Ocean. This true color image of the dust event was acquired on February 11, 2002, by the Moderate-resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra spacecraft. The light brown dust trail can be seen forming an arc a few hundred miles off the coast of Western Sahara and Mauritania. Northeasterly winds blowing across the Atlantic have redirected the dust towards Europe where it will likely settle. For more information and current images of dust storms, visit Natural Hazards on the Earth Observatory . Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  18. Validation of SWEEP for creep, saltation, and suspension in a desert-oasis ecotone

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind erosion in the desert-oasis ecotone can accelerate desertification and thus impacts oasis ecological security. Little is known about the susceptibility of the desert-oasis ecotone to wind erosion in the Tarim Basin even though the ecotone is a major source of windblown dust in China. The object...

  19. Dust-air pollution dynamics over the eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Abdelkader, M.; Metzger, S.; Mamouri, R. E.; Astitha, M.; Barrie, L.; Levin, Z.; Lelieveld, J.

    2015-08-01

    Interactions of desert dust and air pollution over the eastern Mediterranean (EM) have been studied, focusing on two distinct dust transport events on 22 and 28 September 2011. The atmospheric chemistry-climate model EMAC has been used at about 50 km grid spacing, applying an online dust emission scheme and calcium as a proxy for dust reactivity. EMAC includes a detailed tropospheric chemistry mechanism, aerosol microphysics and thermodynamics schemes to describe dust "aging". The model is evaluated using ground-based observations for aerosol concentrations and aerosol optical depth (AOD) as well as satellite observations. Simulation results and back trajectory analysis show that the development of synoptic disturbances over the EM can enhance dust transport from the Sahara and Arabian deserts in frontal systems that also carry air pollution to the EM. The frontal systems are associated with precipitation that controls the dust removal. Our results show the importance of chemical aging of dust, which increases particle size, dust deposition and scavenging efficiency during transport, overall reducing the lifetime relative to non-aged dust particles. The relatively long travel periods of Saharan dust result in more sustained aging compared to Arabian dust. Sensitivity simulations indicate 3 times more dust deposition of aged relative to pristine dust, which significantly decreases the dust lifetime and loading.

  20. Dust exposure in Finnish foundries.

    PubMed

    Siltanen, E; Koponen, M; Kokko, A; Engström, B; Reponen, J

    1976-01-01

    Dust measurements were made in 51 iron, 9 steel, and 8 nonferrous foundries, at which 4,316 foundrymen were working. The sampling lasted at least two entire shifts or work days continuously during various operations in each foundry. The dust samples were collected at fixed sites or in the breathing zones of the workers. The mass concentration was determined by weighing and the respirable dust fraction was separated by liquid sedimentation. The free silica content was determined by X-ray diffraction. In the study a total of 3,188 samples were collected in the foundries and 6,505 determinations were made in the laboratory. The results indicated a definite difference in the dust exposure during various operations. The highest dust exposures were found during furnace, cupola, and pouring ladle repair. During cleaning work, sand mixing, and shake-out operations excessive silica dust concentrations were also measured. The lowest dust concentrations were measured during melting and pouring operations. Moderate dust concentrations were measured during coremaking and molding operations. The results obtained during the same operations of iron and steel foundries were similar. The distribution of the workers into various exposure categories, the content of respirable dust and quartz, the correlation between respirable dust and total dust, and the correlation between respirable silica and total dust concentrations are discussed. Observations concerning dust suppression and control methods are briefly considered. PMID:184524

  1. Saharan dust storms: nature and consequences

    NASA Astrophysics Data System (ADS)

    Goudie, A. S.; Middleton, N. J.

    2001-12-01

    This paper reviews recent work on the role of Saharan dust in environmental change, the location and strength of source areas, the transport paths of material away from the desert, the rates of Saharan dust deposition, the nature of that material (including PeriSaharan loess) and the changing rates of dust activity in response to long and short-term climatic changes. The Sahara produces more aeolian soil dust than any other world desert, and Saharan dust has an important impact on climatic processes, nutrient cycles, soil formation and sediment cycles. These influences spread far beyond Africa, thanks to the great distances over which Saharan dust is transported. The precise locations of Saharan dust source areas are not well known, but data from the Total Ozone Mapping Spectrometer (TOMS) suggest two major source areas: the Bodélé depression and an area covering eastern Mauritania, western Mali and southern Algeria. Trajectories of long-distance transport are relatively well documented, but the links between source areas and seasonal Saharan dust pathways are not. However, it is possible that Harmattan dust from the Bodélé depression may not be the source of the prominent winter plume over the tropical North Atlantic, as is often suggested in the literature. Few of the data on particle size characteristics of Saharan dust are derived from major source areas or from Africa itself. Saharan dusts sampled from the Harmattan plume and over Europe are dominated by SiO 2 and Al 2O 3, a characteristic they share with North American and Chinese dusts. The concentrations of these two major elements are similar to those found in world rocks. PeriSaharan loess is conspicuous by its relative absence, considering the Sahara's dominance of the global desert dust cycle both in the contemporary era and through the geological past. In recent decades, the frequency of Saharan dust events has varied markedly in response to climatic factors such as drought and anthropogenic

  2. Ice nucleation properties of agricultural soil dusts

    NASA Astrophysics Data System (ADS)

    Steinke, Isabelle; Funk, Roger; Busse, Jacqueline; Iturri, Antonela; Kirchen, Silke; Leue, Martin; Möhler, Ottmar; Schwartz, Thomas; Sierau, Berko; Toprak, Emre; Ulrich, Andreas; Hoose, Corinna; Leisner, Thomas

    2015-04-01

    Soil dust particles emitted from agricultural areas contain large amounts of organic material such as fungi, bacteria and plant debris. Being carrier for potentially highly ice-active biological particles, agricultural soil dusts are candidates for being very ice-active as well. In this work, we present ice nucleation experiments conducted in the AIDA cloud chamber. We investigated the ice nucleation efficiency of four types of soil dust from different regions of the world. Results are presented for the immersion freezing and the deposition nucleation mode: all soil dusts show higher ice nucleation efficiencies than desert dusts, especially at temperatures above 254 K. For one soil dust sample, the effect of heat treatments was investigated. Heat treatments did not affect the ice nucleation efficiency which presumably excludes primary biological particles as the only source of the increased ice nucleation efficiency. Therefore, organo-mineral complexes or organic compounds may contribute substantially to the high ice nucleation activity of agricultural soil dusts.

  3. Lidar measurements of Aeolian dust: Mars and Earth

    NASA Astrophysics Data System (ADS)

    Dickinson, C. S.; Davy, R.; Komguem, L.; Junkermann, W.; Whiteway, J. A.

    2009-12-01

    The Phoenix Lidar system was operated in 2008, beginning in Martian northern spring (L_s = 78) through mid summer (L_s = 147). During this period, nighttime observations of dust indicate both persistent background dust up to heights of approximately 15 km, and enhanced dust loading in the Boundary Layer up to heights of approximately 4 km. The magnitude of the optical extinction was observed to decrease within the Boundary Layer with time following summer solstice. This situation is similar to that observed in the Australian desert: a persistent dust layer up to heights of 6 km, with a daytime Convective Boundary Layer increasing up to heights of 4 km during local dust storm activity, and then decreasing during night. A comparative study was undertaken, with the results being augmented by both in situ measurements of the Australian desert dust, as made by over-flying aircraft, and modeled results of Aeolian dust in both environments.

  4. Saharan Dust Export towards the Caribbean: Dust Sources and Atmospheric Circulation over North Africa

    NASA Astrophysics Data System (ADS)

    Schepanski, Kerstin; Heinold, Bernd; Groß, Silke; Schäfler, Andreas; Weinzierl, Bernadett; Sauer, Daniel; Walser, Adrian; Tegen, Ina

    2015-04-01

    Studies analysing satellite observations illustrate the spatial and temporal distribution of emitting dust sources. Results show that high surface wind speeds related to the break-down of the nocturnal low-level jet (LLJ) occurring during the morning hours are frequent driving mechanism for dust uplift in the Sahara desert. Here, we present a study investigating atmospheric circulation pattern over North Africa favouring (a) dust entrainment into the boundary layer and (b) dust export towards the Caribbean Sea. Satellite-based information on the spatio-temporal distribution of dust source activation (DSA) events inferred from 15-minute Meteosat Second Generation (MSG) Spinning Enhanced Visible and InfraRed Imager (SEVIRI) dust observations are linked to atmospheric circulation regimes over North Africa. By means of air-mass trajectories, which map the dust export from North Africa toward the SALTRACE ground observation site at Barbados, cases are selected which link DSA regions with dust events observed at Barbados. These cases are then examined with regard to the atmospheric conditions during dust emission and geomorphologic dust source characteristic. Dust properties inferred from LIDAR observation using the POLIS system and measurements taken during Falcon research flights are compared to the different dust source locations and atmospheric conditions during dust emission. Altogether, the results from this study aim at illustrating the relevance of knowing the dust source locations in concert with the atmospheric circulation. Ultimately, this study addresses the question of what is finally transported across the Atlantic towards the Caribbean from which dust source region.

  5. Source and transportation of summer dust over the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Jia, Rui; Liu, Yuzhi; Chen, Bin; Zhang, Zhijuan; Huang, Jianping

    2015-12-01

    Satellite observational evidences (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations, CALIPSO) have presented that the Tibetan Plateau (TP) is subject to heavy loading of dust aerosols during summer. Combining back trajectory and weather system analyses, the source and transportation of summer Tibetan dust from 2007 to 2014 were investigated. The Tibetan dust is mainly from the Taklimakan Desert and partially from the Gurbantunggut Desert and Great Indian Thar Desert. Case study indicates that the meteorological conditions together with the topography benefit the dust emission adjacent to the TP and the transport toward the plateau. When a cold advection or front developed by strong cold advection passes, dust particles are emitted into the atmosphere from the Taklimakan and Gurbantunggut deserts and then transported to the northern slope of the TP with northeasterly wind induced by the Altai and Tian Shan mountains. For the period from 2007 to 2014, the correlation coefficient of the monthly frequencies of summer dust events over the TP and cold advection passing the Taklimakan and Gurbantunggut deserts were as high as 0.68 and 0.34, respectively. Differently, although the correlation is limited, much TP dust mobilized from the Great Indian Thar Desert is associated with the passing low-pressure system activity and generally polluted by anthropogenic aerosols. The polluted dust is further transported to the southern slope of the TP by the prevailing westerly wind. Investigations on the source and transportation of summer dust over the TP provide a solid foundation of data that can be used to reveal the role of TP dust in the radiation balance, hydrological cycle, and monsoon cycle in India and East Asia.

  6. Camelid genomes reveal evolution and adaptation to desert environments.

    PubMed

    Wu, Huiguang; Guang, Xuanmin; Al-Fageeh, Mohamed B; Cao, Junwei; Pan, Shengkai; Zhou, Huanmin; Zhang, Li; Abutarboush, Mohammed H; Xing, Yanping; Xie, Zhiyuan; Alshanqeeti, Ali S; Zhang, Yanru; Yao, Qiulin; Al-Shomrani, Badr M; Zhang, Dong; Li, Jiang; Manee, Manee M; Yang, Zili; Yang, Linfeng; Liu, Yiyi; Zhang, Jilin; Altammami, Musaad A; Wang, Shenyuan; Yu, Lili; Zhang, Wenbin; Liu, Sanyang; Ba, La; Liu, Chunxia; Yang, Xukui; Meng, Fanhua; Wang, Shaowei; Li, Lu; Li, Erli; Li, Xueqiong; Wu, Kaifeng; Zhang, Shu; Wang, Junyi; Yin, Ye; Yang, Huanming; Al-Swailem, Abdulaziz M; Wang, Jun

    2014-01-01

    Bactrian camel (Camelus bactrianus), dromedary (Camelus dromedarius) and alpaca (Vicugna pacos) are economically important livestock. Although the Bactrian camel and dromedary are large, typically arid-desert-adapted mammals, alpacas are adapted to plateaus. Here we present high-quality genome sequences of these three species. Our analysis reveals the demographic history of these species since the Tortonian Stage of the Miocene and uncovers a striking correlation between large fluctuations in population size and geological time boundaries. Comparative genomic analysis reveals complex features related to desert adaptations, including fat and water metabolism, stress responses to heat, aridity, intense ultraviolet radiation and choking dust. Transcriptomic analysis of Bactrian camels further reveals unique osmoregulation, osmoprotection and compensatory mechanisms for water reservation underpinned by high blood glucose levels. We hypothesize that these physiological mechanisms represent kidney evolutionary adaptations to the desert environment. This study advances our understanding of camelid evolution and the adaptation of camels to arid-desert environments. PMID:25333821

  7. Animals of the Desert.

    ERIC Educational Resources Information Center

    NatureScope, 1985

    1985-01-01

    Provides background information and student activities on how desert animals have adapted to dryness and heat, how and when animals move on the desert, and nocturnal/diurnal animals. Each activity includes objective(s), recommended age level(s), subject area(s), list of materials needed, and procedures. Ready-to-copy pages are included for a…

  8. People and Deserts.

    ERIC Educational Resources Information Center

    NatureScope, 1985

    1985-01-01

    Provides: (1) background information on ways people affect deserts and ways deserts affect people; (2) student activities on this topic; and (3) ready-to-copy materials (culture match worksheet and causes worksheet). Each activity includes objective(s), recommended age level(s), subject area(s), list of materials needed, and procedures. (DH)

  9. Spring Dust Storm Smothers Beijing

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A few days earlier than usual, a large, dense plume of dust blew southward and eastward from the desert plains of Mongolia-quite smothering to the residents of Beijing. Citizens of northeastern China call this annual event the 'shachenbao,' or 'dust cloud tempest.' However, the tempest normally occurs during the spring time. The dust storm hit Beijing on Friday night, March 15, and began coating everything with a fine, pale brown layer of grit. The region is quite dry; a problem some believe has been exacerbated by decades of deforestation. According to Chinese government estimates, roughly 1 million tons of desert dust and sand blow into Beijing each year. This true-color image was made using two adjacent swaths (click to see the full image) of data from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), flying aboard the OrbView-2 satellite, on March 17, 2002. The massive dust storm (brownish pixels) can easily be distinguished from clouds (bright white pixels) as it blows across northern Japan and eastward toward the open Pacific Ocean. The black regions are gaps between SeaWiFS' viewing swaths and represent areas where no data were collected. Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  10. Characteristics of 14C and 13C of carbonate aerosols in dust storm events in China

    NASA Astrophysics Data System (ADS)

    Chen, Bing; Jie, Dongmei; Shi, Meinan; Gao, Pan; Shen, Zhenxing; Uchida, Masao; Zhou, Liping; Liu, Kexin; Hu, Ke; Kitagawa, Hiroyuki

    2015-10-01

    In contrast with its decrease in western China deserts, the dust storm event in eastern China, Korea, and Japan shows an increase in frequency. Although the drylands in northeastern China have been recognized as an important dust source, the relative contributions of dust transport from the drylands and deserts are inconclusive, thus the quantification of dust storm sources in downwind area remains a challenge. We measured the 14C and 13C contents in carbonates of dust samples from six sites in China, which were collected for the duration of dust storm events in drylands, deserts, and urban areas. The δ13C of the dryland dust samples considerably varied in a range of - 9.7 to - 5.0‰, which partly overlapped the desert dust carbonate δ13C ranges. The 14C content of the dryland dust carbonates showed a narrow range of 60.9 ± 4.0 (as an average and 1 SD of five samples) percent modern carbon (pMC), indicating the enrichment of modern carbonate. Dust samples in desert regions contained relatively aged carbonates with the depleting 14C showing of 28.8 ± 3.3 pMC. After the long-range transport of the western China desert dust plume, the carbonates collected at the southern China remained the depletion of 14C (33.5 ± 5.3 pMC) as in the desert regions. On the other hand, the samples of dust storm events at the urban areas of eastern China showed an enrichment of 14C contents (46.2 ± 5.0 pMC, n = 7), which might be explained by the stronger contribution of modern-carbonate-rich dryland dust.

  11. Fingerprints in the Dust

    NASA Technical Reports Server (NTRS)

    2001-01-01

    These MISR nadir-camera images of eastern China compare a somewhat hazy summer view from July 9, 2000 (left) with a spectacularly dusty spring view from April 7, 2001 (middle). The left-hand and middle images are from Terra orbits 2967 and 6928, respectively, and extend from central Manchuria near the top to portions of North and South Korea at the bottom. They are approximately 380 kilometers in width.

    Asia's desert areas are prone to soil erosion, as underground water tables are lowered by prolonged drought and by industrial and agricultural water use. Heavy winds blowing eastward across the arid and sparsely vegetated surfaces of Mongolia and western China pick up large quantities of yellow dust. Airborne dust clouds from the April 2001 storm blew across the Pacific Ocean and were carried as far as North America. The minerals transported in this manner are believed to provide nutrients for both oceanic and land ecosystems.

    According to the Xinhua News Agency in China, nearly one million tons of Gobi Desert dust blow into Beijing each year. During a similar dust outbreak last year, the Associated Press reported that the visibility in Beijing had been reduced the point where buildings were barely visible across city streets, and airline schedules were significantly disrupted. The dust has also been implicated in adverse health effects such as respiratory discomfort and eye irritation.

    The image on the right is a higher resolution MISR nadir-camera view of a portion of the April 7, 2001 dust cloud. It covers an area roughly 250 kilometers wide by 470 kilometers high. When viewed at full magnification, a number of atmospheric wave features, like the ridges and valleys of a fingerprint, are apparent. These are probably induced by surface topography, which can disturb the wind flow. A few small cumulus clouds are also visible, and are casting shadows on the thick lower dust layer.

    Analyses of images such as these constitute one phase of MISR

  12. Characterization of dust sources in Central Asia using Remote Sensing

    NASA Astrophysics Data System (ADS)

    Nobakht, M.; Shahgedanova, M.; White, K.

    2015-12-01

    Central Asian deserts are a significant source of wind-blown desert dust deposited on snow pack and glaciers of the Tian Shan Mountains, affecting both surface reflectance, and therefore melt and runoff, and geochemistry of snow pack and glacier ice. Detailed knowledge of sources of dust, atmospheric pathways, timing and geography of deposition is of crucial importance. This paper focuses on two aspects of desert dust over Central Asia: (i) seasonal and spatial patterns of aerosol optical depth (AOD) of desert dust and (ii) location and seasonal trends in activity of dust sources. Seasonal and spatial distribution of AOD is investigated using Moderate Resolution Imaging Spectroradiometer (MODIS) Deep Blue AOD product, acquired over a period of 12 years from January 2003 to December 2014 at 10 km resolution. More detailed maps of dust sources are produced from higher resolution (1km) MODIS dust enhancement products (DEP) which have been modified by the use of additional bands and change in parameterization. The combined use of AOD and DEP enabled us to identify large scale dust emitting areas (through the use of AOD data) and within these areas, identify smaller-scale eroding points (using DEP) thus significantly improving the knowledge of both dust source location and dust entrainment mechanisms including rapid desertification (e.g. Aral Sea) and post-fire wind erosion (e.g. Lake Balkhash basin). Different seasonal patterns of dust emissions were observed in northern, western and southern deserts around the Tian Shan Mountains and their relation to climatological processes in these regions are explored.

  13. Are Food Deserts Also Play Deserts?

    PubMed

    Cohen, Deborah A; Hunter, Gerald; Williamson, Stephanie; Dubowitz, Tamara

    2016-04-01

    Although food deserts are areas that lack easy access to food outlets and considered a barrier to a healthy diet and a healthy weight among residents, food deserts typically comprise older urban areas which may have many parks and street configurations that could facilitate more physical activity. However, other conditions may limit the use of available facilities in these areas. This paper assesses the use of parks in two Pittsburgh food desert neighborhoods by using systematic observation. We found that while the local parks were accessible, they were largely underutilized. We surveyed local residents and found that only a minority considered the parks unsafe for use during the day, but a substantial proportion suffered from health limitations that interfered with physical activity. Residents also felt that parks lacked programming and other amenities that could potentially draw more park users. Parks programming and equipment in food desert areas should be addressed to account for local preferences and adjusted to meet the needs and limitations of local residents, especially seniors. PMID:27033184

  14. High resolution mapping of dust sources in Central Asia using MODIS imagery

    NASA Astrophysics Data System (ADS)

    Nobakht, Mohamad; Shahgedanova, Maria; White, Kevin

    2015-04-01

    Dust impacts the energy balance of the Earth via absorption and scattering of radiation in the atmosphere and through the mechanism by which aerosols modify the optical properties of clouds and land surfaces. It is now established that the deposition of mineral dust significantly affects high-altitude environments, including both snow pack and glacier ice. Central Asia is a region where large deserts are located in close proximity to the mountains whose extensive glaciers and snow pack provide runoff supporting agriculture in the densely populated foothills. More than 75% of the territory in Central Asia is desert lowland varying from sandy to stony, salt, and clay deserts. Significant amounts of wind-blown desert dust, originating from these deserts, are deposited on glaciers of Tian Shan Mountains in Central Asia. Satellite remote sensing using optical imagery has provided us with a powerful tool for identification and characterization of dust emission sources. In this study we investigated the spatial distribution and seasonal pattern of dust emissions in surrounding lowlands of the Tian Shan Mountains using Moderate Resolution Imaging Spectroradiometer (MODIS) imagery. Seasonality of dust emission is studied by analyzing MODIS Deep Blue aerosol optical depth, acquired over a period of 12 years from January 2003 to December 2014. We analyzed the spatial distribution and frequency of occurrence of dust optical depth to identify the main dust sources in this region. In order to produce a detailed map of dust emission sources, we also employed a dust enhancement algorithm to obtain high resolution (1km) dust enhancement products from MODIS imageries. The high resolution of MODIS dust enhancement products enabled us to identify several small, eroding point sources within the dust source areas. Different seasonal patterns of dust emissions were observed in northern, western and southern deserts around the Tian Shan Mountains and their relation to climatological

  15. EXTREME DUST AND SMOKE EVENTS OVER THE U.S. IN 1998

    EPA Science Inventory

    Dust storms and forest fires are major PM events that occur several times a year over different parts of the US. Such events also originate outside the US, e.g., dust from Sahara and the Asian deserts and smoke from forest fires in Central America and Canada. Such dust and smok...

  16. Dust Detector

    NASA Technical Reports Server (NTRS)

    Kelley, M. C.

    2001-01-01

    We discuss a recent sounding rocket experiment which found charged dust in the Earth's tropical mesosphere. The dust detector was designed to measure small (5000 - 10000 amu.) charged dust particles, most likely of meteoric origin. A 5 km thick layer of positively charged dust was found at an altitude of 90 km, in the vicinity of an observed sporadic sodium layer and sporadic E layer. The observed dust was positively charged in the bulk of the dust layer, but was negatively charged near the bottom.

  17. Dust storm events over Delhi: verification of dust AOD forecasts with satellite and surface observations

    NASA Astrophysics Data System (ADS)

    Singh, Aditi; Iyengar, Gopal R.; George, John P.

    2016-05-01

    Thar desert located in northwest part of India is considered as one of the major dust source. Dust storms originate in Thar desert during pre-monsoon season, affects large part of Indo-Gangetic plains. High dust loading causes the deterioration of the ambient air quality and degradation in visibility. Present study focuses on the identification of dust events and verification of the forecast of dust events over Delhi and western part of IG Plains, during the pre-monsoon season of 2015. Three dust events have been identified over Delhi during the study period. For all the selected days, Terra-MODIS AOD at 550 nm are found close to 1.0, while AURA-OMI AI shows high values. Dust AOD forecasts from NCMRWF Unified Model (NCUM) for the three selected dust events are verified against satellite (MODIS) and ground based observations (AERONET). Comparison of observed AODs at 550 nm from MODIS with NCUM predicted AODs reveals that NCUM is able to predict the spatial and temporal distribution of dust AOD, in these cases. Good correlation (~0.67) is obtained between the NCUM predicted dust AODs and location specific observations available from AERONET. Model under-predicted the AODs as compared to the AERONET observations. This may be mainly because the model account for only dust and no anthropogenic activities are considered. The results of the present study emphasize the requirement of more realistic representation of local dust emission in the model both of natural and anthropogenic origin, to improve the forecast of dust from NCUM during the dust events.

  18. Spatial and temporal variations of spring dust emissions in northern China over the last 30 years

    NASA Astrophysics Data System (ADS)

    Song, Hongquan; Zhang, Kesheng; Piao, Shilong; Wan, Shiqiang

    2016-02-01

    Dust emissions caused by wind erosion have significant impacts on land degradation, air quality, and climate change. Dust from the arid and semiarid regions of China is a main contributor to atmospheric dust aerosols in East Asia, and their impacts can stretch far beyond the territory of China. Spatial-temporal patterns of dust emissions in China over the last several decades, however, are still lacking, especially during the spring season. In this study, we simulated the spatial-temporal dynamics of spring dust emissions from 1982 to 2011 in arid and semi-arid areas of China using the Integrated Wind Erosion Modeling System. Results showed that the most severe dust emission events occurred in the Taklimakan Desert, Badain Jaran Desert, Tengger Desert, and Ulan Buh Desert. Over the last three decades, the magnitude of spring dust emissions generally decreased at the regional scale, with an annual spring dust emission of ˜401.10 Tg. Among different vegetation types, the highest annual spring dust emission occurred in the desert steppes (˜163.95 Tg), followed by the deserts (˜103.26 Tg). The dust emission intensity in the desert steppes and the deserts was ˜150.83 kg km-2·yr-1 and ˜205.46 kg km-2·yr-1, respectively. The spatial patterns of the inter-decadal variation are related to climate change and human activities. Mitigation strategies such as returning farmland to grassland, fenced grazing, and adequate grass harvesting, must be taken to prevent further soil losses and grassland degradation in northern China.

  19. Status and Future of Dust Storm Forecasting

    NASA Astrophysics Data System (ADS)

    Westphal, D. L.

    2002-12-01

    In recent years, increased attention has been given to the large amounts of airborne dust derived from the deserts and desertified areas of the world and transported over scales ranging from local to global. This dust can have positive and negative impacts on human activities and the environment, including modifying cloud formation, fertilizing the ocean, degrading air quality, reducing visibility, transporting pathogens, and inducing respiratory problems. The atmospheric radiative forcing by the dust has implications for global climate change and presently is one of the largest unknowns in climate models. These uncertainties have lead to much of the funding for research into the sources, properties, and fate of atmospheric dust. As a result of advances in numerical weather prediction over the past decades and the recent climate research, we are now in a position to produce operational dust storm forecasts. International organizations and national agencies are developing programs for dust forecasting. The approaches and applications of dust detection and forecasting are as varied as the nations that are developing the models. The basic components of a dust forecasting system include atmospheric forcing, dust production, and dust microphysics. The forecasting applications include air and auto traffic safety, shipping, health, national security, climate and weather. This presentation will summarize the methods of dust storm forecasting and illustrate the various applications. The major remaining uncertainties (e.g. sources and initialization) will be discussed as well as approaches for solving those problems.

  20. What is Desert RATS?

    NASA Video Gallery

    The mission manager and test coordinators for the 2011 mission explain why Desert RATS was started 14 years ago, questions being studied in this year's activities, technologies being tested and the...

  1. African Dust Aerosols as Atmospheric Ice Nuclei

    NASA Technical Reports Server (NTRS)

    DeMott, Paul J.; Brooks, Sarah D.; Prenni, Anthony J.; Kreidenweis, Sonia M.; Sassen, Kenneth; Poellot, Michael; Rogers, David C.; Baumgardner, Darrel

    2003-01-01

    Measurements of the ice nucleating ability of aerosol particles in air masses over Florida having sources from North Africa support the potential importance of dust aerosols for indirectly affecting cloud properties and climate. The concentrations of ice nuclei within dust layers at particle sizes below 1 pn exceeded 1/cu cm; the highest ever reported with our device at temperatures warmer than homogeneous freezing conditions. These measurements add to previous direct and indirect evidence of the ice nucleation efficiency of desert dust aerosols, but also confirm their contribution to ice nuclei populations at great distances from source regions.

  2. Cosmic dust

    NASA Technical Reports Server (NTRS)

    Brownlee, Donald E.; Sandford, Scott A.

    1992-01-01

    Dust is a ubiquitous component of our galaxy and the solar system. The collection and analysis of extraterrestrial dust particles is important to exobiology because it provides information about the sources of biogenically significant elements and compounds that accumulated in distant regions of the solar nebula and that were later accreted on the planets. The topics discussed include the following: general properties of interplanetary dust; the carbonaceous component of interplanetary dust particles; and the presence of an interstellar component.

  3. Concentration, size-distribution and deposition of mineral aerosol over Chinese desert regions

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao Y.; Arimoto, R.; Zhu, G. H.; Chen, T.; Zhang, G. Y.

    1998-09-01

    The mass-particle size distributions (MSDs) of 9 elements in ground-based aerosol samples from dust storm (DS) and non-dust storm (N-DS) periods were determined for 12 sites in 9 major desert regions in northern China. The masses of the 9 elements (Al, Fe, K, Mg, Mn, Sc, Si, Sr and Ti) in the atmosphere were dominated by local mineral dust that averaged 270μg m-3, and the MSDs for the elements were approximately log-normal. On the basis of Al data, the<10μm particles account for ~84% of the total dust mass over the deserts. Model-calculated ("100-step" method) dry deposition velocities (Vd) for the 9 dust-derived elements during N-DS periods ranged from 4.4 to 6.8cms-1, with a median value of 5.6cms-1. On the basis of a statistical relationship between D99% (the dust particle diameter corresponding to the uppermost 1% of the cumulative mass distribution) and Vd, one can also predict dry velocities, especially when D99% ranges from 30 to 70μm. This provides a simple way to reconstruct Vd for dust deposits (like aeolian loess sediments in the Loess Plateau). The estimated daily dry deposition fluxes were higher during DS vs. N-DS periods, but in most cases, the monthly averaged fluxes were mainly attributable to N-DS dust. Two regions with high dust loading and fluxes are identified: the "Western High-Dust Desert" and the "Northern High-Dust Desert", with Taklimakan Desert and Badain Juran Desert as their respective centers. These are energetic regions in which desert-air is actively exchanged, and these apparently are the major source areas for Asian dust.

  4. Sahara Dust

    Atmospheric Science Data Center

    2013-04-15

    article title:  Casting Light and Shadows on a Saharan Dust Storm     ... (nadir) camera. High-altitude cirrus clouds cast shadows on the underlying ocean and dust layer, which are visible in shades of ... was unable to retrieve elevation data. However, the edges of shadows cast by the cirrus clouds onto the dust (indicated by blue and cyan ...

  5. Dust Storm

    Atmospheric Science Data Center

    2013-04-16

    article title:  Massive Dust Storm over Australia     View ... at JPL September 22, 2009 - Massive dust storm over Australia. project:  MISR category:  ... Sep 22, 2009 Images:  Dust Storm location:  Australia and New Zealand ...

  6. PERSPECTIVE: Dust, fertilization and sources

    NASA Astrophysics Data System (ADS)

    Remer, Lorraine A.

    2006-11-01

    Aerosols, tiny suspended particles in the atmosphere, play an important role in modifying the Earth's energy balance and are essential for the formation of cloud droplets. Suspended dust particles lifted from the world's arid regions by strong winds contain essential minerals that can be transported great distances and deposited into the ocean or on other continents where productivity is limited by lack of usable minerals [1]. Dust can transport pathogens as well as minerals great distance, contributing to the spread of human and agricultural diseases, and a portion of dust can be attributed to human activity suggesting that dust radiative effects should be included in estimates of anthropogenic climate forcing. The greenish and brownish tints in figure 1 show the wide extent of monthly mean mineral dust transport, as viewed by the MODerate resolution Imaging Spectroradiometer (MODIS) satellite sensor. The monthly mean global aerosol system for February 2006 from the MODIS aboard the Terra satellite Figure 1. The monthly mean global aerosol system for February 2006 from the MODIS aboard the Terra satellite. The brighter the color, the greater the aerosol loading. Red and reddish tints indicate aerosol dominated by small particles created primarily from combustion processes. Green and brownish tints indicate larger particles created from wind-driven processes, usually transported desert dust. Note the bright green band at the southern edge of the Saharan desert, the reddish band it must cross if transported to the southwest and the long brownish transport path as it crosses the Atlantic to South America. Image courtesy of the NASA Earth Observatory (http://earthobservatory.nasa.gov). Even though qualitatively we recognize the extent and importance of dust transport and the role that it plays in fertilizing nutrient-limited regions, there is much that is still unknown. We are just now beginning to quantify the amount of dust that exits one continental region and the

  7. Dust Storm Hits Canary Islands

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A thick pall of sand and dust blew out from the Sahara Desert over the Atlantic Ocean yesterday (January 6, 2002), engulfing the Canary Islands in what has become one of the worst sand storms ever recorded there. In this scene, notice how the dust appears particularly thick in the downwind wake of Tenerife, the largest of the Canary Islands. Perhaps the turbulence generated by the air currents flowing past the island's volcanic peaks is churning the dust back up into the atmosphere, rather than allowing it to settle toward the surface. This true-color image was captured by the Moderate-resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra satellite, on January 7, 2002. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  8. Long-term EARLINET dust observations

    NASA Astrophysics Data System (ADS)

    Mona, Lucia; Amiridis, Vassilis; Amodeo, Aldo; Binietoglou, Ioannis; D'Amico, Giuseppe; Schwarz, Anja; Papagiannopoulos, Nikolaos; Papayannis, Alexandros; Sicard, Michael; Comeron, Adolfo; Pappalardo, Gelsomina

    2015-04-01

    Systematic observations of Saharan dust events over Europe are performed from May 2000 by EARLINET, the European Aerosol Research LIdar NETwork. EARLINET is a coordinated network of stations that make use of advanced lidar methods for the vertical profiling of aerosols. The backbone of EARLINET network is a common schedule for performing the measurements and the quality assurance of instruments/data. Particular attention is paid to monitoring the Saharan dust intrusions over the European continent. The geographical distribution of the EARLINET stations is particularly appealing for the dust observation, with stations located all around the Mediterranean and in the center of the Mediterranean (Italian stations) where dust intrusions are frequent, and with several stations in the central Europe where dust penetrates occasionally. All aerosol backscatter and extinction profiles related to observations collected during these alerts are grouped in the devoted "Saharan dust" category of the EARLINET database. This category consists of about 4700 files (as of December 2013). Case studies involving several stations around Europe selected from this long-term database have been provided the opportunity to investigate dust modification processes during transport over the continent. More important, the long term EARLINET dust monitoring allows the investigation of the horizontal and vertical extent of dust outbreaks over Europe and the climatological analysis of dust optical intensive and extensive properties at continental scale. This long-term database is also a unique tool for a systematic comparison with dust model outputs and satellite-derived dust products. Because of the relevance for both dust modeling and satellite retrievals improvement, results about desert dust layers extensive properties as a function of season and source regions are investigated and will be presented at the conference. First comparisons with models outputs and CALIPSO dust products will be

  9. Saharan dust episodes and pregnancy.

    PubMed

    Dadvand, Payam; Basagaña, Xavier; Figueras, Francesc; Amoly, Elmira; Tobias, Aurelio; de Nazelle, Audrey; Querol, Xavier; Sunyer, Jordi; Nieuwenhuijsen, Mark J

    2011-11-01

    Desert dust is one of the natural contributors to atmospheric particulate matter worldwide. Although particulate pollution has been shown to adversely affect pregnancy, the available evidence on the impact of dust episodes on pregnancy is very scarce. The aim of this study was to evaluate the impact of Saharan dust episodes on pregnancy complications (preeclampsia and bacteriuria) and outcomes (birth weight and gestational age at delivery). This study was based on a cohort of births (N = 3565) that occurred in a major university hospital in Barcelona during 2003-2005. To determine Saharan dust episodes, we developed a two-stage approach based on meteorological evidence of the presence of Saharan dust cloud over the region and unusually high levels of particulate levels on the ground while taking account of traffic sources. The associations between the number of Saharan dust episodes during whole pregnancy as well as each pregnancy trimester and pregnancy complications and outcomes were analysed. There were 152 days (out of 838 days) with Saharan dust cloud over the region from which 45 days were determined as episodic days. We did not observe any statistically significant harmful effect of Saharan dust episodes on our included pregnancy complications and outcomes. However, we observed a small but statistically significant increase in gestational age at delivery in association with the number of episodic days during the third trimester and whole pregnancy (0.8 and 0.5 days respectively). Our findings were not suggestive for any adverse effect of Saharan dust episodes on our included pregnancy complications and outcomes. PMID:21964628

  10. Circumstellar dust

    NASA Technical Reports Server (NTRS)

    Dwek, E.

    1986-01-01

    The presence of dust in the general interstellar medium is inferred from the extinction, polarization, and scattering of starlight; the presence of dark nebulae; interstellar depletions; the observed infrared emission around certain stars and various types of interstellar clouds. Interstellar grains are subject to various destruction mechanisms that reduce their size or even completely destroy them. A continuous source of newly formed dust must therefore be present for dust to exist in the various phases of the interstellar medium (ISM). The working group has the following goals: (1) review the evidences for the formation of dust in the various sources; (2) examine the clues to the nature and composition of the dust; (3) review the status of grain formation theories; (4) examine any evidence for the processing of the dust prior to its injection into the interstellar medium; and (5) estimate the relative contribution of the various sources to the interstellar dust population.